I IIIIIIIIIIIIIIIII

N8427979 Informa_on is our business.

DEVELOPMENTOF

ADHESIVES USED

A QUALIFICATION STANDARDFOR

IN HYBRID MICROCIRCUTTS

ROCKWELL INTERNATIONAL CORPORATION

ANAHEIM, CA

DEC 81

U.S. DEPARTMENT OFCOMMERCE

National Technical Information Service
N84-27979

DEVELOPMENT OF A QUALIFICATION STANDARD FOR

ADHESIVES USED IN HYBRID MICROCIRCUITS

Rockwell International Corporation

Anaheim, CA

Dec 81
NASA .CONTRACTOR

REPORT

(_ASA-CR-161978) DEVELOPMENT O_ A

QUALIFICA_ON STANDAHD FOJ_ ADBESZVES USED IN

hZBS_D _IC_OC_COI_S ?inal Contractor

_eport (Rock.well ;:_uternatioaa/ Corp.].' 118 p Unclas

BC &O6/_F A01 CSCL 09C G3/33 19717

DEVELOPMENT OF A QUALIFICATION STANDARD FOR ADHES IVES

USED IN HYBRID MICROCIRCUITS

H84-2 7979

By J. J. Licari, B. L. Weigand, and C.

Rockwell International Corporation

Electronic Device Division

P. O. Box 4t92

Anaheim, California 92803

Final Report, Mod 3

December 198t

A. Soykin

Date of general release: February 1984

Prepared for

NASA - George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama

REPRODUCEDBY

NATIONAL TECHNICAL

INFORMATION SERVICE

U.S. DEPARTMENT OF COMMERCE

SPRINGFIELD, VA. 22).61
NOTICE

THIS DOCUMENT HAS BEEN REPRODUCED

FROM THE BEST COPY FURNISHED US BY

THE SPONSORING AGENCY. ALTHOUGH IT

IS RECOGNIZED THAT CERTAIN PORTIONS

ARE ILLEGIBLE, IT IS BEING RELEASED

IN THE INTEREST OF MAKING AVAILABLE

AS MUCH INFORMATION AS POSSIBLE.
TECHNICAL REPORT STANDARD TITLE PAGE

3. RECIPIENT_S CATALOG NO. r'l REPORT NO. 12. GOVERNMENT ACCESSION NO.

NASA CR-161978 I

4. TITLE AND SUBTITLE

Development of a Qualification Standard for Adhesives Used

in Hybrid Microcircuits

7. AUTHOR(S)

J. J. Licari, B. L. Weigand_ and C. A. Soykin

9. PERFORMING ORGANIZATION NAME AND ADDRESS

Rockwell International Corporation

Electronic Device Division

P. O. Box 4i92

Anaheim, California 92803

12. SPONSORING AGENCY NAME AND ADDRESS

National Aeronautics and Space Administration

Washington, DC 20546

5. REPORT DATE

December t981

6. PERFORMING ORGANIZATION CODE

8. PERFORMING ORGANIZATION REPORr #

10. WORK UNIT NO.

1. CONTRACT OR GRANT NO.

NAS8-33385

13. TYPE OF REPOR', & PERIOD COVERED

Contractor Report

Final, Mod 3

14. SPONSORING AGENCY CODE

15. SUPPLEMENTARYNOTES

Technical Monitor: Salvadore V. Caruso

Final Report, Mod 3,

16. ABSTRACT

The objective of this program was to develop improved qualification standards

and test procedures for adhesives used in microelectronic packaging. The test

methods in MSFC-SPEC-592, "Specification for the Selection and Use of Organic Adhesives in Hybrid Microcircuits," were re-evaluated versus industry and government

requirements. Four electrically insulative and four electrically conductive adhesives

used in the assembly of hybrid microcircuits were selected to evaluate the proposed

revised test methods. The intent of this effort was to develop parametric data to

establish specification requirements for adhesives used in assembly of hybrid microcircuits for space applications rather than to establish a list of qualified sources

for the specification.

Based on the results of this study, MSFC-SPEC-592 was revised and rewritten

into military specification format. An estimate of the cost to perform qualification

testing of an adhesive to the requirements of the revised specification was also

prepared.

17. KE't WORDS

Corrosivity

Outgassing

Volume Resistivity

Thermal Conductivity

19. SECURITY CLASSIF. (of this rep(rt_

Unclassified

MSFC - Form 3292 (May 1959)

SECURITY CLASSIF. (of this page ) 121. NO. OF PAGES 22. PRICE

Unclassified [ I 18 NTIS

For sale by National Technical Information Service, Springfield, Virginia

I

m

22151
ORIGINAL PA(_ 1_

OF POOR QUALITY

FOREWORD

This report describes work performed from October 1980 to

October 1981 under Contract lqAs8-33385, Modification No. 3, for

the George C. Marshall Space Flight Center, National Aeronautics

and Space Administration, Marshall Space Flight Center, Alabama.

The technical manager for MSFC was Mr. S. V. Caruso. This report

was prepared by Rockwell International, Autonetics Strategic

Systems Division, under the direction of Dr. J. J. Licari, Manager

of Interconnect Systems Engineering. The principal investigator

was Dr. B. L. Weigand. The principal participant in the program

was Mrs. C. A. Soykino

ii
SECTION

1.0

2.0

3.0

TABLEOFCONTENTS

2.1 TASKA

•2.2 TASKB

2.3 TASKC

INTRODUCTIONANDPROGRAMOBJECTIVE...........

PROGRAMSUMMARY ...................

INDUSTRYREVIEW..............

EVALUATIONOFTESTMETHODSANDREQUIREMENTS.

DEVELOPMENT OFELECTRICALSTABILITYTEST. .

2°4 TASKD ADHESIVEVALUATION............

2.5 TASKE SPECIFICATIONREVISION ..........

2.6 TASKF COSTDATAFORMATERIALSTESTING......

EXPERIMENTAL PROCEDURES ANDRESULTS ..........

3.1 TASKA INDUSTRYREVIEW .............

3.2 TASKB EVALUATIONOFTESTMETHODSANDREQUIREMENTS°

3.2.1 Infrared Spectrum .............

3.2°2 Outgassing ................

3.2.3 Hardness .................

3.2.4 BondShear Strength ............

3.2.5 Corrosivity ................

3.2.6 VolumeResistivity .............

3.2.7 Thermal Conductivity ............

3.2.8 Linear Thermal Expansion Coefficient ....

3.2.9 lonic Impurities ..............

3.2.10 Dielectric Constant and Dissipation Factor .

3.3 TASKC DEVELOPMENT OFELECTRICALSTABILITYTEST. .

3.4 TASKD ADHESIVEVALUATION............

3.4.1 Selection of Adhesives ...........

3.4.2 Infrared Analysis ..............

3.4.3 Outgassing ................

3.4.4 BondShear Strength Tests .........

3.4.5 Corrosivity Test Results ..........

3.4.6 VolumeResistivity .............

PAGE

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iii
SECTION

TABLEOFCONTENTS(C0nt)

PAGE

3.4.6.1 Electrically Conductive Adhesives 73

3.4°6.2 Electrically Insulative Adhesives 76

3.4.7 Thermal Conductivity ........... 80

3.4.8 Linear Thermal Expansion Coefficient . . . 80

3.4.9 lonic Impurities ............. 84

3.4.10 Dielectric Constant and Dissipation Factor . 86

3.5 TASKE SPECIFICATIONREVISION.......... 88

3.6 TASKF COSTDATAFORMATERIALSTESTING ..... 88

4.0 CONCLUSIONS..................... 90

5.0 RECOMMENDATIONS .................... 92

APPENDIXA .......................... 93

REFERENCES .......................... 109

iv
FIGURE

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II

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20

21

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LIST OF ILLUSTRATIONS

Electrical Stability Test Specimen . o ..........

Electrical Stability Test Fixture ............

SEM Photograph of Ablebond 36-2 Attached Gold-Plated

Kovar Tab .......................

SEM Photograph of Epo-Tek H20E Attached Gold-Plated

Kovar Tab ........................

SEM Photograph of Ablebond 58-6 Attached Gold-Plated

Kovar Tab .................

SEM Photograph of Epo-Tek H44 Attached Gold-Plated

Kovar Tab ........................

Infrared Spectrum of Ablebond 36-2 ............

Infrared Spectrum of Ablebond 58-6 ............

Infrared Spectrum of Ablebond 41-I ............

Infrared Spectrum of Epo-Tek H2OE, Part A ........

Infrared Spectrum of Epo-Tek H7OE, Part A ........

Infrared Spectrum of Epo-Tek H2OE, Part B ........

Infrared Spectrum of Epo-Tek H7OE, Part B ........

Infrared Spectrum of Ablefilm 550 ............

Infrared Spectrum of Epo-Tek H44 ............

Infrared Spectrum of Epo-Tek H77, Part A ........

Infrared Spectrum of Epo-Tek H77, Part B ........

Weight. Loss of Epo-Tek H20E (TGA) in Nitrogen ......

Weight Loss of Ablebond 36-2 (TGA) in Nitrogen ......

Weight Loss of Epo-Tek H44 (TGA) in Nitrogen ......

Weight Loss of Ablebond 58-6 (TGA) in Nitrogen ......

Weight Loss of Epo-Tek H70E (TGA) in Nitrogen

Cured 30 Minutes at 150°C ...............

Weight Loss of Epo-Tek H70E (TGA) in Nitrogen

Cured 60 Minutes at 150°C ...............

Weight Loss of Epo-Tek H77 (TGA) in Nitrogen .......

PAGE

13

13

2O

2O

21

21

25

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FIGURE

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36

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38

39

40

41

42

43

44

45

LIST OF ILLUSTRATIONS (Cont)

Weight Loss of Ablebond 41-I (TGA) in Nitrogen .....

Weight Loss of Ablefilm 550 (TGA) in Nitrogen .....

Package (Prior to Seal) Used for Gas Analysis of

Nonconductive Adhesives ...............

Package (Prior to Seal) Used for Gas Analysis of

Electrically Conductive Adhesives ...........

Small Semiconductor Die Shear Test Specimen ......

Large Semiconductor Die Shear Test Specimen ......

Small Capacitor Shear Test Specimen ..........

Large Capacitor Shear Test Specimen ..........

Substrate Shear Test Specimen ............

Comparison of Bond Shear Strength Results for Small

Transistors (0.051 x 0.051 cm) ............

Comparison of Bond Shear Strength Results for Intermediate Size Transistors (0.102 x 0.102 cm) ......

Comparison of Bond Shear Strength Results for Substrate

Chips (0.127 x 0.127 x 0.038 cm) ...........

Comparison of Bond Shear Strength Results for Small

Capacitors (0.127 x 0.102 x 0.102 cm) .........

Comparison of Bond Shear Strength Results for Large

Capacitors (0.699 x 0.216 x 0.152 cm) .........

Small Capacitor Test Specimen Showing Bond Area Used .

Large Capacitor Test Specimen Showing Bond Area Used

Jig Used to Prepare Volume Resistivity Test Specimens

Jig with Transparent Tape Applied as Mask on Glass Slide

Jig with Test Specimen After Removal of Masking Tape .

Test Fixture for Volume Resistivity Measurements . . .

Plot of Thermal Conductivity Versus Density .....

PAGE

38

39

42

42

56

56

57

57

58

65

66

67

68

69

72

72

75

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77

77

82

vi
LIST OFTABLES

TABLE

1

8

9

I0

II

12

13

14

15

16

17

18

19

20

VolumeResistivity (Milliohm-cm) vs Temperatureand

Density .........................

Calculated Resistive Heating of Gold Filled Adhesives

with Current Density of 186 A/cm2 (1200 A/in 2) Applied

Results of Electrical Stability Tests at 150°Cand

Zero Current Density ..................

Results of Electrical Stability Tests at 150°Cand

Current Density of 54.3 Amps/cmL (350 Amps/inch2) ....

Results of Electrical Stability Tests at 150°Cand

Current Density of 93 Amps/cmL (600 Amps/inch2) .....

Results of Electrical Stability lests at 150°Cand

Current Density of 139.5 Amps/cmz (900 Amps/inch2)

VolumeResistivity Calculated Using Kovar Tabs Bonded

to Thin Film Gold Conductors ..............

Adhesives Selected for Evaluation of Qualification Tests.

Results of Weight Loss (TGA)Tests ...........

Results of GasAmbient Analyses of PackagesContainlng

Epo-TekH20E ......................

Results of GasAmbientAnalyses of PackagesContalnlng

Epo-TekH44 .......................

Results of Gas#_nbientAnalyses of PackagesContainlng

Ablebond 36-2 ......................

Results of GasAmbientAnalyses of PackagesContaining

Ablebond58-6 ....... ...............

Results of GasAmbientAnalyses of PackagesContalnlng

Epo-TekH77 .......................

Results of GasAmbientAnalyses of PackagesContalnlng

Ablebond 41-I ......................

Results of GasAmbient Analyses of PackagesContalnlng

Ablefilm 550 ......................

Results of GasAmbient Analyses of PackagesContaining

Epo-TekH70E ......................

Comparisonof Weight Loss MeasurementProcedures ....

Devices and Substrates Selected for BondShear Tests

Comparisonof BondShear Strength Results for Small

Transistors (0.051 x 0.051 cm) .............

PAGE

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vii
TABLE

21

22

23

24

25

26

27

28

29

30

31

32

33

34

LIST OFTABLES(Cont)

Comparisonof BondShear Strength Results for

Intermediate Size Transistors (0.102 x 0.102 cm) ....

Comparisonof BondShear Strength Results for

Substrate Chips (0.127 x 0.127 x 0.038 cm) .......

Comparisonof BondShear Strength Results for

Small Capacitors (0.127 x 0.102 x 0.102 cm) ......

Comparisonof BondShear Strength Results for

Large Capacitors (0.699 x 0.216 x 0.152 cm) ......

Corrosivity Test Results ................

Results of VolumeResistivity Tests of Electrically

Conductive Adhesives ..................

VolumeResistivities of Electrically Insulative

Adhesives ........................

Thermal Conductivity Test Results ...........

Linear Thermal Expansion Coefficients and Glass

Transistion Temperatures ...............

Results of lonic Impurity Analyses ...........

Results of Dielectric Constant Measurements ......

Results of Dissipation Factor Measurements.......

Qualification Cost Estimate ..............

Comparisonof Adhesive Performancewith Proposed

Specification Requirements ...............

PAGE

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74

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81

83

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87

87

89

91

viii
1.0 INTRODUCTIONADPROGRAMOBJECTIVE

Epoxyadhesives of both the electrically insulative and

electrically conductive types are widely used in the assembly

of high reliability hybrid microcircuits. The first government

specification for procurementof epoxy adhesives for use in

hybrid microcircuits was issued for coordination as MSFCDrawing 16A02053NASA/MSFCin December1974. The specification was

based on work performed by Rockwell International. (1,2) Only

a minor numberof commentswere received from the coordination

and the specification was subsequently released as MSFC-SPEC-592,

"Specification for the Selection and Use of Organic Adhesives

in Hybrid Microcircuits" on May22, 1978. This specification

with minor revisions was also released by the ArmyMissile

Commandas MIS 28962on 29 November1976 and by the National

Security Agencyas Specification NSANo. 77-25 on 27 May1977.

Since implementation of the specification, someproblems

have been encountered in the qualification of adhesives to its

requirements. Areas of concern Include outgassing (effects of

filler content and effects on devices), bond shear strength

(numberof specimens, requirement at 150oc, die shear versus

lap shear), corrosivity (test methodand requirements), volumeresistivity (test method), ionic impurities (test method

and requirements), electrical stability (test method), and

frequency of qualification testing.

The objective of this programwas to resolve these problems and to develop improvedqualification standards and test

procedures for adhesives used in microelectronic packaging.
2.0 PROGRAMSUMMARY

This programconsisted of the following five tasks.

2.1 TASK A INDUSTRY REVIEW

Organic adhesives are being used extensively in microelectronic circuits for industry, government, and commercial applications. However, the qualification and selection of specific

materials have not been standardized. This has resulted in

reliability defects in both short and long term applications.

A telephone survey was conducted to determine the state-of-theart methods used for qualification and control of adhesives and

to assess the extent to which MSFC-SPEC-592 was being used in

industry.

2.2 TASK B EVALUATION OF TEST METHODS AND REQUIREMENTS

The test methods and requirements in MSFC-SPEC-592 were

evaluated versus industry and government requirements using the

results from Task A and changes were recommended where required.

2.3 TASK C DEVELOPMENT OF ELECTRICAL STABILITY TEST

Under conditions of time and elevated temperature, certain

combinations of conductive adhesives and semiconductor die decrease in conductivity. Then, electrical properties such as

VCESAT increase and affect the operation of the device(s). A

test method was developed to evaluate the electrical stability

of the adhesives when powered at high current densities (to

139.5 amps/cm 2) and at a temperature of 150°C. Additional

effort would be required to develop a method for evaluating

the electrical stability of the large variety of semiconductor

die and adhesive combinations taking into consideration the

type of die backing, die size, current density, and type of

adhesive filler.
2.4 TASKD

2.5

2.6

ADHESIVEVALUATION

Eight epoxy adhesives, four electrically conductive (two

silver filled and two gold filled) and four electrically insulative, were selected to evaluate the test methodsand procedures proposed for the revised specification. The intent of

this effort was to develop parametric data to be used to establish

specification requirements for the adhesives used in assembly of

hybrid microcircuits for space applications rather than to establish

a list of qualified sources for the specification.

TASK E SPECIFICATION REVISION

Based on the results of the above tests and the conclusions

and recommendations derived therefrom, MSFC-SPEC-592 was revised

and rewritten into military specification format.

TASK F COST DATA FOR MATERIALS TESTING

An estimate was prepared of the cost of material and labor

required to perform qualification testing of an adhesive.
3.0 EXPERIMENTAL PROCEDURES ANDRESULTS

3.1 TASK A INDUSTRY REVIEW

It was determined that while efforts were underway to qualify adhesives to the specifications, difficulties were being

encountered with both the test procedures and test requirements.

Problem areas included:

(I) Outgassing - Many felt that the metal filled adhesives

were favored and that the weight loss should be based on

the volume rather than weight of adhesive used.

(2) Shear strength - The specifications require a minimum

of 800 die shear tests for adhesive qualification

not including shelf life testing. This was considered

excessive. Some preferred lap shear to die shear

testinfl.

(3) Corrosivity - The simpler aluminized mylar test specified in NAS 77-25A was preferred.

(4) Volume resistivity - The use of an adhesive strip

on a glass slide was preferred over the ASTM D2739

method for electrically conductive adhesives.

(5) Thermal conductivity - Difficulties were encountered

in obtaining data at 150oc. A single test temperature of 121°C was recommended.

(6) Linear thermal expansion coefficient - Method does

not adequately provide for film adhesives.

(7) lonic impurities - This test should be required for electrically conductive adhesives also. Difficulties were also

encountered in meeting the cnlorlde requirement.

(8) Electrical stability - An improved test for the

effect of time, temperature and current density on

the ohmic contact to semiconductor devices is needed.

(9) Retention of qualification requirements - Most preferred that

requalification be required at 24 rather than 12 month

intervals.
(I0) General comments- The maximumtemperature for adhesive cure and use of 150°Cwas considered by some

to be low and does not provide for polyimide adhesives. The use of two specifications, one for the

adhesive vendor and one for the microcircuit manufacturer was also recommended.

The survey revealed that General Dynamicsis using MIS28962for the qualification of adhesives. Martin Marietta is

using both MIS-28962and NSANo. 77-25 and Beckmanis using

NSA77-25. Nocompanieswere qualifying to MSFC-SPEC-592_however, it should be noted that both the NSAand Army specifications

are basedon the MSFCspecification.

3.2 TASK B EVALUATION OF TEST METHODS AND REQUIREMENTS

Based on a review of MSFC-SPEC-592 and the problem areas

discussed above, the following changes in test methods and

requirements were selected for evaluation:

3.2.1 INFRARED SPECTRUM

This method was changed to permit solvent extraction of the

resin from the filler. No changes in requirements were proposed.

3.2.2 OUTGASSING

It was proposed to make the manufacturer of the adhesive

responsible for determining the thermal stability of the adhesive

at 250°C using thermogravimetric analysis (TGA). The weight

loss at 250oc must be (___0.3 wt. percent. The microcircuit manufacturer must insure that his cure, vacuum bake, and sealing

process will provide a package ambient meeting the requirements of MIL-STD-883, Method 1018. The short and long term

weight loss requirements were deleted.

3.2.3 HARDNESS

It was proposed to delete this test which is of little
benefit as a qualification test and is of concern only in some

microwaveapplications.

3.2.4 BOND SHEAR STRENGTH

The bond shear strength test was revised to reduce the number

of shear tests from approximately 800 to a total of I00 per adhesive. Die shear rather than lap shear testing was retained

since the former test represents the actual use configuration.

Since the adhesion of large capacitors is very dependent on the

bonding process (i.e. amount of fillet, total area bonded, use

of electrically insulative adhesive for the total bond or for

bonding the center of the capacitor), it was proposed to require

the microcircuit manufacturer to perform this test. Performance

of the semiconductor and substrate die shear tests will be required

of the adhesive manufacturer and made optional for the microcircuit manufacturer.

3.2.5 CORROSlVlTY

The aluminized mylar corrosivity test specified in NSA

No. 77-25A was evaluated in place of the more complex voltage

bias-humidity test now specified in MSFC-SPEC-592.

3.2.6 VOLUME RESISTIVITY

The volume resistivity test method specified in NSA No.

77-25A was evaluated in place of the ASTM D2739 method now

specified in MSFC-SPEC-592.

3.2.7 THERMAL CONDUCTIVITY

Thermal conductivity measurements are presently required

"at approximately 70oc, 120oC and 150°C ''. It was proposed that

this requirement be revised to measure at 121 +5°C only. This

temperature approximates the maximum junction temperature in

most semiconductor devices and would be the value most commonly
required in heat conduction studies. Thermal conductivity normally decreases as the temperature increases so the use of a

value obtained at 121°Cwould provide a conservative value for

conduction calculations at lower temperatures.

3.2.8 LINEAR THERMAL EXPANSION COEFFICIENT

Due to the difficulties involved in preparing specimens of

the film adhesives, it was proposed to limit this test to paste

adhesives only. For the film adhesives the expansion in the X

and Y directions would be comparable to the glass alone and this

value could be used in any calculations necessary. The expansion

of the film adhesives in the Z direction is not critical to

device or substrate adhesion or cracking in most applications.

3.2.9 IONIC IMPURITIES

This test was made a requirement for both electrically conductive and electrically insulative adhesives. Requirements

for resistivity, pH, chloride, sodium, and potassium were based

on the results of the tests performed in Task D (Paragraph 3.4.9).

3.2.10 DIELECTRIC CONSTANT AND DISSIPATION FACTOR

The dielectric constant and dissipation factor of the electrically insulative adhesive were determined in accordance with

ASTM DI50 at frequencies of IKHz and 1MHz at 25C.
3.3 TASK C DEVELOPMENT OF ELECTRICAL STABILITY TEST

In order to determine theelectrical stability of the electrically conductive adhesives, volume resistivity versus temperature and current density measurements were performed over the

temperature range of -65 to 150oC using current densities of

7.75 to 186 amps/cm 2 (50 amps/in 2 to 1200 amps/in2). The results are shown in Table I. The results are an average of

three specimens/adhesive. The specimens and measurement procedure were identical to those described in paragraph 3.4.6.1

for measuring volume resistivity.

Both silver filled adhesives, Epo-Tek H20E and Ablebond

36-2, showed no change in volume resistivity with increasing

current density up to 186 amps/cm 2 (1200 amps/in2). The gold

filled adhesives however, showed evidence of resistive heating

at current densities of 46.5 amps/cm (300 amps/in 2) and greater

for Epo-Tek H44 and 62 amps/cm 2 (400 amps/in 2) and greater for

Ablebond 58-6. Based on the TCR values, the calculated temperature increases for the gold filled adhesives with 186.0

amps/cm 2 (1200 amps/in 2) applied are given in Table 2. The

temperature coefficient of resistivity was calculated using

the equation:

TCR(ppm/°C) = (R2R_ _ XI06

- TI)

were R2 = resistivity at the higher temperature T 2

R1 = resistivity at the lower temperature T 1

The temperature rise was calculated using the TCR values obtained at current density 7.75 amps/cm 2 and the difference

between the resistivity at 186 and 7.75 amps/cm 2 as the

R2 - R1 value. These temperature increases could seriously

impact the validity of any thermal analysis performed on a

microcircuit if they are not taken into consideration when

using gold filled adhesives. While a current density of

1200 amps/in 2 may be considered to be high, small signal

transistors 0.02 x 0.02 inches square may have currents up

8
TABLE 1 VOLUMERESISTIVITY(MILLIOHM-CM)vs TEMPERATURE ANDCURRENTDENSITY

Tempi

Adhesive (°C) 7,750

-65 0,147

0 0.176

Epo-Tek 25 0,185

H20E 50 0,196

I00 0.218

150 0,235

-65 0,652

0 0,791

Epo-Tek 25 0,844

H44 50 0,899

I00 1,010

150 1,120

-65 0.132

0 0,157

Ablebond 25 0,167

36-2 50 0,177

I00 0.197

150 0,214

-65 0.822

0 0.989

Ablebond 25 1.050

58-6 50 1.130

lO0 1.260

150 1.460

15,50! 31.00

i

ii

J

I

,<---_: 0.844

<----L> 1 0,899

46,50

Current Density (A/cm 2)

62,00 77,50 93,00 108.50 124,00 139,50 155,00 17Q,50 186,00

I ....... > 0,147

........................ > O. 174

> 0,185

..... ...................... _ 0.196

....................... _ 0,218

..... _" 0.235

0.652 0.653 0,654 0,654 0,655 0,657 0,659 0,661 0,663

0,791 0,792 0,792 0.793 0,794 0,797 0,798 0,801 0,804

0,845 0,846 0,847 <-----_I 0.847 0.8491 0.851 0.853 0,856 0.860

0,900 0,900 0,901 0,901 0.902 0,904! 0,905 0,907 0,910 0.913

.... _ 1,010 1.020 _ 1.020 1,030 1,030 1,030

1,120 1,130 c _ 1,130 1.140

i

< ;

I

l

I

0.821

,- 0.132

............ _- 0.157

...... _" 0,167

> 0,177

.... )" 0,197

m- 0,214

0.821 0.822 0.823 0.823 0.824 0.826 0.828 0.831 0.834 0.836

0.989 0.990 0.993 0.993 0.994 0.995 0.998 l.O00 l.O00 l.OlO

1.050 1.060 < > 1.060 1.070 1.070 1.080

_ 1.130 1.140 _ 1.140 1.150

> 1.260 1.270 _ 1.270 1.280 1.280

> 1.460 1.470 1.470 1.480 1.490 1.500 1.510 1.520

r |4
TABLE 2 CALCULATED RESISTIVE HEATING OF GOLD FILLED ADHESIVES

WITH CURRENT DENSITY OF 186 A/cm 2 (1200 A/in 2) APPLIED

Epo Tek H44

Substrate Temp. (°C) Calc. TCR Calc. Temp. Rise (°C) Calc. TCR

-65 3280 5.1 3126

0 2680 6.1 2467

25 2607 7.3 3048

50 2469 6.3 2301

lO0 2178 9.1 3175

150 1800" 9.9 3000*

Ableb0nd 58-6

Calc. Temp. Rise (°C)

5.4

8.6

9.4

7.7

5.0

13.7

oo

O_

;Urr- i'i'_

* Estimated Value
to 0.5 amps applied yielding a current density of 1250 amps/in 2.

The effects of increasing current density on the volume resistivity found in this study do not agree with the results

reported by Dr. Jerry E. Sergent (3) Sergent found current

densities greater than 15.92 A/cm 2 (102.7 A/in 2) caused a

decrease in the volume resistivity of all 15 electrically conductive adhesives which he evaluated including the four adhesives studied in this program. The specimen configuration

used by Sergent differed in that the materials were cast in a

Rexolite mold with a line width and thickness of 8.0 x lO-2cm

and 0.157 cm, respectively, giving a cross-sectional area of

1.26 x 10 -2 cm2. The line width, thickness, and cross-sectional

area used in this study were approximately 0.25 cm, 7.62 x lO-3cm,

and 1.94 x 10-3 cm2, respectively. A new test specimen 0.127

x 0.051 cm in width and thickness, respectively, was prepared

on a glass slide using Ablebond 36-2. Our previous measurements used a constant voltage of 5 volts. The voltage used

by Sergent was not specified. Current density measurements

were performed at 25oc on the new specimen using voltages of

0.I, 0.4, I, 2, 4, 8, and I0 with current densities to 591

amps/in 2. No changes in the volume resistivity with voltage

or current were noted. Based on the above, no reason for the

differences in results can be given.

Little is known about the current carrying capability

of the conductive adhesives over either the long or short term.

The data reported above indicates that the silver filled adhesives can tolerate current densities of at least 186 amps/cm 2

for short periods of time. Resistive heating of the gold-filled

adhesives could make them less reliable than the silver filled

at high-current densities.

It was planned to use the current density at which a

5 percent decrease in volume resistivity occurred as a guide in

establishing a current density limit for the adhesives. Since

II
no decrease occurred, the following methodwas selected for evaluating the electrical stability of the conductive adhesives at

150ocand current densities of O, 54.3, 93 and 139.5 amps/cm2

(0, 350, 600 and 900 amps/inch2).

Thermal dissipation would be a major problem in continuous

burn-in of transistors or diodes at highcurrent densities and

temperatures. The contact resistance at the interface between

the transistors or diodes and adhesives has also showna dependance on the type of adhesive (i.g., gold or silver filled), the

type of backing on the device and the size of the device, as

well as the current density applied. (3,4,5) Resolution

of all of these problems is beyondthe scope of this program.

Kovar tabs (gold plated) were therefore selected to evaluate

the electrical stability of the adhesives at high temperature

and current densities independent of the effects of the interface interactions.

The test specimensconsisted of gold plated Kovar tabs

0.0635 x 0.0635 cm (0.025 x 0.025 inch) bondedto thin film

gold conductors on alumina substrates using the adhesive to

be evaluated. The tabs and conductors were interconnected

with ultrasonic bondedgold wires (0.0381 mm)to form a series

of nine interconnected tabs as shownin Figure I. Twoseries

of tabs, each series bondedwith a different adhesive were

used per substrate (3.81 x 1.91 cm) and three substrates

were_usedfor each current density evaluated. The adhesive

fillet was removedfrom around the tabs to control the bond

area to 0.00403 cm2 per tab. Eachseries of tabs was individually biased at 5.3 + 0.5 volts using resistors to control

the current densities. Contact to the thin film gold conductors wasmadeusing spring loaded contacts in the fixture shownin Figure 2.

The test fixtures were placed under bias in an oven

at 150°Ccontaining a nitrogen ambient. Resistance measurements were madeinitially and at the intervals shownin

12
ORIGINAL PAGE

BLACK AND WHITE PHOTOGRAPH"

Figure I. Electrical Stability Test Specimen

Figure 2. Electrical Stability Test Fixture

13
Tables 3 through 6. All measurements were made at 25°C using

four point probes (Keithley Model 191 Digital Multimeter).

All of the adhesives showed little or no change in the

measured resistances after lO00 hours at 150oc and current

densities of O, 54.3, 93, and 139.5 amps/cm 2. Some instability

in the resistance measurements was noted for all four adhesives

at a current density of 54.3 amps/cm 2 after 260 hours (Table 4)

but all measurements had stablized at 550 hours and thereafter.

These results indicate that the adhesives have excellent current carrying capability when not bonded to semiconductor

devices.

Resistance measurements were also made from the top of

the Kovar tabs to the thin film conductors at the conclusion

of the test using the substrates which had been powered at

139.5 amps/cm 2. The resistances measured by the four point

probe averaged 0.024 ohms for the two gold filled adhesives

and 0.019 ohms for the two silver filled adhesives. Assuming

the primary resistance is due to the adhesive and calculating

for the volume resistivity gave the results shown in Table 7.

Comparison of these resistivity values with those in Table 2

shows the resistivities of the silver filled adhesives to

be approximately 500 times higher while those of the gold

filled adhesives are approximately lO0 times higher than

those previously measured using adhesive strips. Mason's(4)

results (Table 7) were 7,800 times higher using an unidentified silver filled adhesive for attachment of a semiconductor.

The contact resistance at the adhesive interface is therefore

much greater than that indicated by the measurements performed

using the adhesive strip on a glass slide. Figures 3 through 6

are SEM photographs (2048X) showing the metal particle distribution in the adhesives. The silver platelets (Figures 3 and

4) are parallel to and show fewer contacts at the bond interface than the more spherical gold particles (Figures 5 and 6).

This may explain the higher contact resistance for the silver

filled adhesives.

14
TABLE

ORIGINAL PAGE 15

OF pOOR QUALII"Y

RESULTS OF ELECTRICAL STABILITY TESTS

AT 150oc AND ZERO CURRENT DENSITY

Adhesive

Specimen

Ablebond 36-2 (I)

Ablebond 36-2 (2)

Ablebond 36-2 (3)

Average

Epo-Tek H20E (I)

Epo-Tek H20E (2)

Epo-Tek H20E (3)

Average

Ablebond 58-6 (4)

Ablebond 58-6 (5)

Ablebond 58-6 (6)

Average

Epo-Tek H44 (4)

Epo-Tek H44 (5)

Epo-Tek H44 (6)

Average

Resistance (ohms) a

Hours at ]50°C "

0 260 400 550 715 1000

0.926

0.837

0.922

0.895

0.952

0.844

0.896

0.897

0.960

0.845

0.894

0.900

0.5!9

0.853

0.510

0.627

0.894

0.848

0.960

0.901

0,960

0.851

0.960

0.924

0.885

0.912

0.866

0.888

0.874

0.888

0.851

0.871

O. 874

0.887

o.84o

0.867

0.869

0.882

0.845

0.865

0.875

0.890

0.856

0.874

0.873

0.888

0.853

0.871

0.950

1.056

1.075

1.027

1.118

1.029

0.951

1.033

0.9i9

1.054

1.056

1.010

1.102

1.010

0.513

0.875

0.918

1.059

1.060

1.012

0.598

1.009

0.946

0.851

0.906

1.058

1.054

1.006

1 .I03

1.008

O.390

0.834

0,839

1.065

I. 060

0.988

0.559

1.023

0.518

O. 700

m ,.

0.913

1.063

1.056

1.011

1.109

1.020

0.495

0.875

acombined resistance of 9 gold plated Kovar tabs (0.0635 x 0.0635 cm)

adhesively bonded in series to thin film gold conductors and wire

bonded with 0.038 mm gold wire.

15
ORIGINAL PAC--_ |5

OF POOR QUALITY

TABLE 4

Adhesive

Specimen

Ablebond 36-2 (7)

Ablebond 36-2 (8)

Ablebond 36-2 (9)

Average

Epo-Tek H20E (7)

Epo-Tek H20E (8)

Epo-Tek H20E (9)

Average

Ablebond 58-6 (lO)

Ablebond 58-6 (ll)

Ablebond 58-6 (12)

Average

Epo-Tek H44 (lO)

Epo-Tek H44 (ll)

Epo-Tek H44 (12)

Average

RESULTS OF ELECTRICAL STABILITY TESTS

AT 150oc AND CURRENT DENSITY OF 54.3 AMPS/CM 2

(350 AMPS/INCH _)

0.580

0.920

0.581

0.694

0.983

0.888

0.978

0.950

1.090

1.062

1.054

1.069

0.996

1.001

0.991

0.996

260

l.O fb

O.926

l.043

0.990

0.960

0.850

0.960 f

0.923

1.30 f

l.O f

0.987

1.096

O.963 f

0.950

0.910

0.941

Resistance (ohms)a

Hours at

400

l.Of

O.931

l.046

0.992

0.948

0.868

0.966

0.927

1.064

1.074

1.020

l.053

0.971

0.986

0.971

0.976

150°C

550

l.Ol2

0.920

1.050

0.994

0.955

0.869

0.956

0.927

l.043

I.060

l.017

1.040

0.970

0.970

0.962

0.967

715

l .018

0.932

l .091

l.014

0.956

0.871

0.999

0.925

l .053

l.060

l.023

1.045

t

0.975

0.975

0.962

0.971

1000

1.014

0.931

1.067

1. 004

0.947

0.876

0.927

0.917

1.041

1.057

l.Ol5

1.049

0.972

0.978

0.965

0.972

acombined resistance of 9 gold plated Kovar tabs (0.0635 x 0.0635 cm)

adhesively bonded in series to thin film gold conductors and wire

bonded with 0.038 mm gold wire.

bf = fluctuating resistance.

16
ORIGINAL PA_Z |S

OF POOR QUALITY

TABLE RESULTS OF ELECTRICAL STABILITY TESTS

AT 150oc AND CURRENT DENSITY OF 93 AMPS/CM 2

(600 AMPS/INCH 2)

Adhesive

Specimen

Ablebond 36-2 (13)

Ablebond 36-2 (14)

Ablebond 36-2 (15)

Average

Epo-Tek H20E (13)

Epo-Tek H20E (14)

Epo-Tek H20E (15)

Average

Ablebond 58-6 (16)

Ablebond 58-6 (17)

Ablebond 58-6 (18)

Average

J

Epo-Tek H44 (16)

Epo-Tek H44 (17)

Epo-Tek H44 (18)

Average

0

0.952

0.936

0.945

0.944

0.889

0.882

0.873

0.881

O.974

l .064

l .055

1.031

l.063

0.951

0.992

1.002

260

0.930

0.920

0.942

0.931

0.878

0.922

0.856

0.885

0.934

1.035

1.034

l.OOl

1.047

0.930

0.960

O.979

Resistance (ohms)a

Hours at 150°C

400

0.927

0.918

O.948

0.931

0.875

0.862

0.862

0.866

0.933

1.040

1.037

1.003

1.049

0.933

0.962

0.981

550

0.927

0.920

0.935

0.927

0.876

0.853

0.845

0.858

0.930

1.030

1.029

0.996

1.031

0.930

0.959

0.973

715

O.927

0.915

0.939

0.927

0.879

0.857

0.849

0.862

0.927

l .037

I.030

0.998

1.043

0.932

0.956

0.977

lO00

O.926

0.921

O.938

0.928

0.881

0.856

0.848

0.862

0.921

1.034

1.032

0.996

l.048

0.922

0.963

0.978

acombined resistance of 9 gold plated Kovar tabs (0.0635 x 0.0635 cm)

adhesively bonded in series to thin film gold conductors and wire

bonded with 0.038 mm gold wire.

17
OF pOOR _:J_o,L__

TABLE 6 RESULTS OF ELECTRICAL STABILITY TESTS

AT 150oc AND CURRENT DENSITY OF 139.5 AMPS/CM2

(900 AMPS/INCH 2)

Adhesive

Specimen

Ablebond 36-2 (19)

Ablebond 36-2 (20)

Ablebond 36-2 (21)

Average

Epo-Tek H20E (19)

Epo-Tek H20E (20)

Epo-Tek H20E (21)

Average

Ablebond 58-6 (22)

Ablebond 58-6 (23)

Ablebond 58-6 (24)

Average

Epo-Tek H44 (22)

Epo-Tek H44 (23)

Epo-Tek H44 (24)

Average

0.944

1.059

0.962

0.988

O.874

l.009

0.910

0.931

0.994

1.051

0.972

1.006

1.082

0.978

1.054

1.038

260

0.956

l.OlO

0.963

0.976

0.851

0.993

0.886

0.910

0.958

1.024

0.958

0.980

1.056

0.960

1.050

1.022

Resistance (ohms)a

Hours at |50°C

400

0.945

1.069

0.999

1.004

0.853

1.003

0.890

0.915

0.963

1.035

0.957

0.985

1.058

0.965

1.058

l .027

550

0.940

1.080

0.953

0.991

0.852

O.968

0.887

0.902

0.954

1.025

0.954

O. 978

1.064

0.962

1.040

1.022

O.956

l .065

0.885

0.969

0.859

1.010

0.896

0.922

0.956

1.028

O. 960

0.981

1.058

O. 969

1.046

l.024

0.926

l.049

O.933

O. 969

0.836

0.994

0.842

0.891

0.933

1.015

0.871

0.940

1.056

0.961

1.028

l.Ol5

acombined resistance of 9 gold plated Kovar tabs (0.0635 x 0.0635 cm)

adhesively bonded in series to thin film gold conductors and wire

bonded with.O.038 mm gold wire.

18
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Figure 3. SEM Photograph of Ablebond 36-2

Attached Gold-Plated Kovar Tab

ORIGINAL PAG_

BLACK AND WHITE PHOTOGRAPI-I"

Figure 4. SEM Photograph of Epo-Tek H20E

Attached Gold-Plated Kovar Tab

2O
BLACK AND WHITE PHOTOGRAr!r

Figure 5. SEM Photograph of Ablebond 58-6

Attached Gold-Plated Kovar Tab

Figure 6. SEM Photograph of Epo-Tek H44

Attached Gold-Plated Kovar Tab

21
Mason (4) attributed the nonohmic contact obtained between

semiconductor dice which did not have properly sintered gold

backings and silver-filled epoxy to the metal-semiconductor

rectifying junction formed at the semiconductor-junction interface. He also found that silicon transistors greater than 0.08

inch square, when attached with silver-filled epoxy, exhibit an

initial increase in contact resistance when exposed to high

temperature and then decline to a value near the initial value.

He attributed these changes to a pressure buildup of trapped

gases which gradually diffuse to the atmosphere. Li (5) found

a linear relationship between the die elevation slope and the

long term weight loss characteristics of a silver-filled and

a gold-filled epoxy. He used this data to define a maximum

die size for a given epoxy. Additional studies are required

to verify this relationship and to determine the effect of

step cures, cure duration and temperature, and vacuum bake,

either during or following cure, on the stability of the ohmic

contact to semiconductor devices.

3.4 TASK D ADHESIVE EVALUATION

3.4.1 SELECTION OF ADHESIVES

Eight adhesives currently in use for assembly of microcircuits were selected for evaluation of the test methods and

procedures proposed for the revised specification in paragraph

3.2. The results of these tests were used to establish parametric requirements for the specification. A list of the

selected adhesives is given in Table 8. Four of the adhesives are electrically conductive (two silver filled and two

gold filled) and four are electrically insulative (including

one film adhesive).

22
TABLE8. ADHESIVESSELECTEDFOREVALUATIONOFQUALIFICATIONTESTS

Adhesive

Epo-Tek H20E

Epo-Tek H44

Epo-Tek H70E

Epo-Tek H77

Ablebond 36-2

Ablebond 58-6

Ablefilm 550

Ablebond 41-I

2 Component Silver Filled

Single Component Gold Filled

2 Component, Nonconductive

Filler

2 Component, Nonconductive

Filler

Single Component Silver

Filled

Single Component Gold Filled

Glass Supported Film, Nonconductive

Single Component Calcium

Carbonate Filled Nonconductive

Vendor

Epoxy Technology

Epoxy Technology

Epoxy Technology

Epoxy Technology

Ablestik Laboratories

Ablestik Laboratories

Ablestik Laboratories

Ablestik Laboratories
OF POOR QUALn'Y

3.4.2

3.4.3

INFRARED ANALYSIS

The infrared spectra of the adhesives are shown in Figures 7

through 17. Comparison of the spectra of Ablebond 36-2, Ablebond 58-6,

and Ablebond 41-1, Figures 7 through 9 respectively, shows the three

adhesives contain identical epoxy resins and curing agents and differ

only in the fillers used. The epoxy resin is reported (Ablestik Laboratories) to be resorcinol diglycidyl ether while the curing agent

is reported to be an aromatic substituted urea. Epo-Tek H20E and

H70E also contain identical epoxy resins, Figures lO and II, and curing

agents, Figures 12 and 13. The resin and curing agent were not identified. The spect_mof Ablefilm 550 reported (Ablestik Laboratories)

to consist of a mixture of a nitrile-modified epoxy and dicyandiamide

curing agent is shown in Figure 14. The spectra of Epo-Tek H44 and

Epo-Tek H77, Parts A and B, are shown in Figures 15 through 17, respectively. The epoxy resins and curing agents used for these adhesives were not identified.

The infrared spectra were obtained by separation of the fillers

from the resins and/or curing agents using acetone as the solvent

followed by evaporation of the acetone on the sodium chloride window prior to analysis.

OUTGASSING ANALYSIS

The thermal stability of the adhesives was determined as a

function of temperature up to 450°C in nitrogen. The results are

shown in Figures 18 through 26. The NASA specification requirement is a weight loss <0.3 wt % at 250°C. The measured weight

losses, manufacturers'recommended, and actual cure schedules

used are shown in Table 9. It can be seen that the cure schedules would have to be extended beyond those used for the Epo-Tek

H2OE, Epo-Tek H7OE, Ablebond _!-I and Ablefilm 550 in order to

meet the weight loss requirement as it now stands.

24
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M:)

m CKMAI_

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w_ mm I.io .......

bOVl_O II_,*_• . .

PAlm # _. _.

CONe ......

lc_./'_l_¢ I_.l ".

ll_KMAF

... i..v,.

!.?.

i:l\

-.n

n

l

:1

°- . , , , .

I:' IF

I! I

F...* ...

I..u..

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,..|..

i

_- -_.- _,_

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__ '"'" _._.L.E._.LF:tXIT"r".,:,"T4'_:I, " : n __:r__H

*:" ::1 I"i" '_!.2_:_'._1:!:I _"_ !_1_::_ "_/I'V_I,_I "1':!rl'Yl' r:UIII[H.T,.I=TrFi.T "TJ'::'I'TT"':1"'1'"I'"I"TT'Tq'-I

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...... I-,.-,

....... I.._i.... !....... -_.:_i._.(_..-L ._2..I_LI.2-1...LI ._1............

WAVIIMO_II| I I:_ "1

Figure 14. Infrared Spectrum of Ablefilm 550

_/ _ ....

! ..

W_VI_Ul ¢_1 _l

. • • . o e • e a o o . . - -

- - • o • _ _ o • • • • e . . . a, o _ LI I •

Figure 15. Infrared. Spectrum of Epo-Tek H44

_:)l_

CT._,
[,I. O,

..I

n," nIL

O0

0 _ed 'LLH _loJ.-od3_o mn.A_odS po-_Ul "/-L o_n6.t_

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V _aed "LLH _al-od3 lo uJnuloads paaealuI "9L a.m6.L-I

*0aeomll_

........ encl_

;]i ......."_ ....

"

.... !_ i.. .:i ............. _,0,,,-o_

..J. ......... o_0,_oe

_ } i ........... -

_i_i,_ _, 'i ....._'"'"""

80 el, eE It_ _ Ot Oe&el _ _ el Ill II • O • |¢ a e

1:2;3".

eiJlwOjO_Oij "))_1

qVIN)4_.. _ IR

- - _vo

- ..... I,-InAme

I ,,-_.;:_,

. , . " " " " _ 0 ....... -[. _ q__: _ _ , _ _.,. _ " : _¢_G_ C_ _ " ----" ........

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TABLE 9.

Adhesives

Manufacturers'

Recommended Cure

(Hours @ 150oc)

Epo-Tek H20E

Ablebond 36-2

Epo-Tek H44

Ablebond 58-6

Epo-Tek H70E

Epo-Tek H77

Ablebond 41-1

Ablefilm 550

O.083

0.5

0.5

0.5

0.083

0.5

0.5

2.0

RESULTS OF WEIGHT LOSS (TGA) TESTS

_ure Weight

Schedule Used Loss

(Hours @ 150°C) @ 250°c (%)

l.O

l.O

l.O

l.O

0.5 and l.O

l.O

l.O.

4.0

0.8

0.0

0.0

0.I

1.5 (l.O)a

0.3

l.O

1.5

O0

o2

_r

),9

r-l'=

aAfter l hour at 150°C
The water vapor content of the gases emitted from the adhesives was also determined in accordance with MIL-STD-883B, Method

1018.2, Procedure I. Four test packages (2.54x2.54xO.279 cm) were

prepared for each adhesive. Two of the packages were gold plated

Kovar and two were nickel plated Kovar in each case.

Only nickel plated lids were available for sealing the packages.

To avoid schedule delays the nickel plated lids were used on all

of the packages. The packages were leadless to prevent leakage

problems at the glass seal but this will not be made a specification requirement. An example of the internal package configuration

used for the nonconductive (substrate) adhesives is shown in

Figure 27. The substrate dimensions are 1.91xl.91xO.064 cm.

An example of the internal package configuration used for the

electrically conductive adhesive is shown in Figure 28. A total

of 22 devices (0.127x0.127 cm), calculated to be sufficient to

cover approximately I0 percent of the area of a substrate normally

used in a package of this size, were bonded directly to the

package base with the adhesive to be tested. (This is assumed to

be the average device density in a Package of this size.) The

adhesives were all cured at 150°C for double the time specified

by the vendors as shown in Table 9. Following cure, the packages

were vacuum-baked for 16 hours at 150°C at < 6.67 pascals (believed to be the minimum requirement), hermetically sealed by

seam welding in dry nitrogen and leak tested in accordance with

MIL-STD-883B, Method 1014.1, Test Conditions A1 and CIo Prior

to gas ambient analysis, the packages were baked at 125oc for

168 hours (to simulate burn-in) and allowed to stand for 24 hours

at 25°C in air.

The results of the gas ambient analyses are shown in Tables

I0 through 17. All four of the electrically conductive adhesives,

Epo-Tek H20E and H44 and Ablebond 36-2 and 58-6, Tables I0 through

13 showed little or no water vapor in the packages. The amount of

41
Figure 27. Package(Prior to Seal) Used for Gas

Analysis of Nonconductive Adhesives

OF POOR QUALITY,

Figure 28. Package (Prior to Seal) Used for Gas Analysis

of Electrically Conductive Adhesives

42
TABLE I0 RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING EPO-TEK H20E

AMU Specie

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

31 Methanol

50 Methyl Chloride

9l Toluene

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone Detected, less than O.OOl

bNone Detected, less than 0.030

Gold

..... Concentration(%By Volume)

Nickei Nickel

Plated with Plated with

Packages .... Lids

H2OEAI H2OEA2

0.003

NDa

0.011

NDb

99.939

NDa

0.013

0.034

ND b

NDa

NDa

NDa

<l.Ox10-9

1.42

NDa

NDa

0.008

NDb

99.957

NDa

0.008

0.027

NDb

NDa

NDa

NDa

<].Ox]O-9

1.28

Plated

Packages

H2OENI

NDa

NDa

0.012

NDb

99.968

NDa

0.001

0.019

NDb

NDa

NDa

NDa

<1.OxlO-9

1.44

Nickel

Plated

Lids

H2OEN2

NDa

NDa

0.009

NDb

99.966

NDa

O.OlO

0.015

NDb

NDa

NDa

NDa

<l.OxlO T

1.46

I'T; :r"
TABLE II • RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING EPO-TEK H44

4::=

Gold

Concentr.ation (% By Volume)

Nickel Nickel _ckel

AHU Specie

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

Plated with Plated

Packages ....... Lids

H44A1 H44A2

0.001

NDa

0.0]2

NDb

99.981

NDa

NDa

0.006

NDb

NDa

NDa

0.011

NDb

99.989

NDa

NDa

NDa

NDb

31 Methanol

50 Methyl Chloride

91 Toluene

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone D_tected, less than 0.001

bNone D_tected, ]ess than 0.030

NDa

NDa

NDa

<1.0x10-9

1.45

NDa

NDa

NDa

<1.0xlO -9

1.37

Plated

Packages

H44NI

NDa

NDa

0.013

NDb

99.977

ND

0.002

0.008

NDb

NDa

NDa

NDa

<I .Ox10---g--

1.50

with Plated

Lids

H44N2

NDa

NDa

0.014

0.0750

98.714

1.084

0.058

0.055

ND b

NDa

NDa

NDa

7.6x10-7

1.34

O0

o

;0P

,o-a

r"m

_F
TABLE 12 . RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING ABLEBOND 36-2

AHU Specie

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

31 Methanol

50 Methyl Chloride

91 Toluene

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone Detected, less than 0.001

bNone Detected, less than 0.030

. Copcentration (% By Volume)

Gold Nickel Nickel

Plated with Plated Plated with

Packa es Lids Package s

36-2AI . 36-2A2 36-2N1

Nickel

Plated

Lids

36-2N2

0.001

NDa

0.011

NDb

99.964

NDa

NDa

0.024

NDb

NDa

NDa

NDa

<I.0xi0-9

1.18

ND a

O. 331

0.010

O. 2850

97.814

I .403

0.066

0.091

ND b

NDa

NDa

ND a

3.2xi0-9

I .55

O.003

NDa

0.011

NDb

99.971

NDa

0.001

0.014

NDb

NDa

NDa

NDa

<I. 0x10 -9

I .38

NDa

NDa

0.011

NDb

99,970

NDa

0.001

0.018

ND b

NDa

ND a

NDa

<I .Ox10 -9

I .54

oom

z

r-m
TABLE 13. RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING ABLEBOND 58-6

AMU Specie

, , , , ,

Gold

Plated

Packages

58-6A1

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

31 Methanol

50 Methyl Chloride

91 Toluene

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone Detected, less than 0.001

bNone Detected, less than 0.030

Concentration

Nickel

with Plated

0.001

NDa

0.0]2

ND b

99.927

NDa

0.001

0.059

ND b'

NDa

NDa

NDa

," ,

<1.0xlO -9

1.41

Lids

58-6A2

0.004

NDa

O.OlO

NDb

99.9]9

NDa

O.OOl

0.066

NDb

NDa

NDa

NDa

, , , , ,

(% By Volume)

Nickel

Plated wi

PackaBes

58-6NI

NDa

NDa

0.011

NDb

99.944

NDa

NDa

0.045

Nickel

th Plated

Lids

58-6N2

NDa

NDa

0.010

NDb

99.938

NDa

0.001

0.051

<1.0x10-9

1.44

NDb

NDa

NDa

NDa

<l.Ox]O-9

1.46

NDb

NDa

NDa

NDa

<I .Ox10 -9

I .49

oo

u

_0r-

_Q

I-rtt
TABLE 14 RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING EPO-TEK H77

.p=

"-d

AMU Specie

2 Hydrogen

4 Helium

15 Methane

&

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

31 Methanol

50 Methyl Chloride

91 Toluene

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone Detected, less than 0.001

bNone Detected, less than 0.030

Concentration

Gold Nickel

Plated with Plated

Packages Lids

H77AI

0.003

NDa

0.044

NDb

99.088

NDa

0.001

0.849

ND b

NDa

0.015

NDa

<1.0x10-'9"

1.18

H77A2

0.002

NDa

0.037

NDb

99.317

NDa

NDa

0.637

NDb

NDa

0.007

NDa

<i.oxio-9

1.19

By Volume)

Nickel

Plated wi

Packages

H77N1

0.001

NDa

0.020

ND b

99.541

NDa

0.014

0.424

NDb

NDa

NDa

NDa

<1.0x10-9

1.31

Nickel

th Plated

Lids

H77N2

0.001

NDa

0.018

ND b

9.9.525

NDa

0.014

0.442

NDb

NDa

NDa

NDa

<I .OxlO-9

I .34

oo

r" r_l

m
TABLE 15. RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING ABLEBOND 41-I

4_

O0

AMU Specie

"Gold J'

Plated

Packages

41-IAI

Concentration

..... Nicke'i'

with Plated

Lids

41 -IA2

(% By Volume)

Nickel

Plated with

Packapes

41-INI

Nickel

Plated

Lids

41-IN2

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 An_onia

31 Methanol

50 Methyl Chloride

91 Toluene

0.010

NDa

0.016

2.5070

95.351

NDa

0.002

2.114

NDb

NDa

ND a

NDa

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

<1.0xlO -9

1.28

0.0O6

NDa

0.015

2.2830

95.538

NDa

NDa

2.158

NDb

NDa

NDa

NDa

<I.0xi0-9

1.13

0.007

NDa

0.014

2.3380

96.135

NDa

0.002

1.504

NDb

NDa

NDa

NDa

<l.Ox10-9

1.36

u,,

0.O07

NDa

0.023

l.8900

96.491

NDa

0.001

1.588

ND b

NDa

NDa

NDa

<I .OxlO -9

I .25

oo

"n_o

KD'o

r-r_

aNone Detected, less than 0.001

bNone Detected, less than 0.030
TABLE 16. RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING ABLEFILM 550

AMU Specie

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

31 Methanol

50 Methyl Chloride

91 Toluene

Gold

Plated with

Packages

5_0AI

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone Detected, less than 0.001

0.021

NDa

0.073

0.3070

98.489

NDa

0.001

0.182

0.805

0.122

NDa

NDa

<1.0x10-9

1.i7

Concentration (% By Volume)

Nickel

Plated

Lids

550A2

0.013

NDa

0.060

0.2790

99.001

NDa

NDa

0.122

0.420

0.105

NDa

NDa

<1.0x10-9

1.14

NiCkel

Plated

Paskages

550NI

0.021

NDa

0.078

0.3100

98.750

NDa

NDa

0.110

0.629

0.102

NDa

NDa

<I .0xi0-9

I .33

with

Nickel

Plated

Lids

550N2

0.015

NDa

0.O72

0.2570

98.828

ND a

0.001

0.137

O.549

0.141

NDa

NDa

<1.0xlO-9

1.23

oO

_n_j

_._ ,_)

cw
TABLE 17. RESULTS OF GAS AMBIENT ANALYSES OF PACKAGES CONTAINING EPO-TEK H70E

C_

AMU Specie

2 Hydrogen

4 Helium

15 Methane

18 Water Vapor

29 Nitrogen

32 Oxygen

40 Argon

44 Carbon Dioxide

17 Ammonia

31 Methanol

50 Methyl Chloride

91 Toluene

Measured Leak Rate (scc/sec He)

Volume of Gas @ 25°C (cc)

aNone Detected, less than 0.001

Gold Nickei

Plated with Plated

Packages Lids

H7OEAI -

Concentration (% By

0.005

O. 767

0.018

O.4570

H7OEA2

0.007

NDa

0.012

Volume)

Nickel Nickel

Plated with Plated

Packages Lids

HTOENI H7OEN2

0.016

ND a

0.057

0.0970 0.5180

0.037

NDa

0.107

0.7280

97.644

0.691

0.073

0.223

0.122

NDa

NDa

NDa

.... , . |

1.6x10-8

1.11

99.619

NDa

0.010

0.071

0.184

NDa

NDa

NDa

98.484

NDa

0.012

0.181

0.661

0.071

ND a

ND a

<1.0x10-9

1.26

<1.0x10-9

1.33

97.470

NDa

0.041

0,346

1.082

0.163

NDa

0.O26

<l .OxlO -9

l .28

O0

m

"OQ

,0_.

O_

_r

_Q

r-r_
carbon dioxide in the packages was also quite low. The only

packages showing detectable water vapor (>300 ppm) were H44N2

(Table II), and 36-2A2 (Table 12) which were shown to be leakers

by the presence of oxygen/helium.

In the case of the nonconductive adhesives only Epo-Tek H77

(Table 14) showed no detectable water vapor. The carbon dioxide

content of the H77 packages was approximately an order of magnitude

higher than that of the packages containing electrically conductive

adhesives, however, and the gold-plated packages with nickel-plated

lids showed traces of methyl chloride (70 and 150 ppm) while the

entirely nickel-plated packages showed less than I0 ppm, the limit

of detectability. The packages containing Ablebond 41-I (Table 15)

showed the highest water vapor content (18,900 ppm to 25,070 ppm)

and the highest carbon dioxide content (15,040 ppm to 21,580 ppm).

A much longer vacuum bake would be required to reduce the water

vapor content to the MIL-STD-883 requirement of < 5000 ppm. The

packages containing Ablefilm 550 (Table 16) showed an acceptable

water vapor content of 2570 to 3!00 ppm but showed high levels of

ammonia (4,200 to 8,050 ppm) and methanol (1,020 to 1,410 ppm).

The ammonia, which is basic, can cause corrosion of aluminum metallization while the methanol can serve both as a freezing point

depressant for water and as a conductive medium for the ammonia

or ionic impurities increasing the corrosion potential. A much

longer vacuum bake and/or higher cure temperature and time would

again be required for the Ablefilm 550 to reduce the ammonia and

methanol levels. The packages containing Epo-Tek H70E (Table 17)

show a considerable variation in the contents of the gas ambients.

While package H7OEAI shows an acceptable leak rate of 1.6xi0-8

scc/sec He, it is an obvious leaker based on the helium, oxygen

and argon contents. Comparison of the results for package

H7OEA2 which is gold-plated with a nickel-plated lid with those

for packages H7OENI and H7OEN2 which are entirely nickel-plated

51
showsa higher water vapor, carbon dioxide and ammoniacontent for

the nickel-plated packagesand the presence of methanol only in

the nickel-plated packages. PackageH7OEN2also showed260 ppmof

toluene. A larger sample size would be required to determine if

there is a significant difference in the results for the gold and

nickel-plated packages. The results do indicate, however, that

the sealing process requires further development to reduce the water

vapor, ammonia, and methanol contents.

Infrared analysis, Figures 6 and 7, showed Epo-Tek H20E and

H70E to be identical except for the fillers used. The H2OE, Table I0,

showed no detectable water vapor or ammonia while the H7OE, Table 17,

showed significant amounts of both materials. The infrared spectra

of Ablebond 36-2, 58-6 and 41-I, Figures 3 through 5, also showed

them to be identical except for the fillers. The Ablebond 36-2

and 58-6 (Tables 12 and 13) showed no detectable water vapor and

minor amounts of carbon dioxide while Ablebond 41-I (Table 15)

showed significant amounts of both. It is therefore apparent that

the filler can significantly affect the outgassing of the adhesive.

A comparison of weight loss measurements based on thermogravimetric analysis (TGA) and water vapor emission based on mass spectrometric analysis (MS) are shown in Table 18. It can be seen that

a good correlation exists for the acceptable adhesives (TGA: <

0.3 wt%, MS<5000 ppm) with the exception of Epo-Tek H20E which

would fail the TGA requirement. Longer cures and/or higher cure

temperatures would undoubtably allow all of the adhesives to meet

the TGA requirement. Similarly, longer cures and/or higher cure

temperatures combined with a longer vacuum bake and/or higher

bake temperature, would probably allow all of the adhesives to meet the

water vapor requirement. (The cure temperature/vacuum bake

temperature are limited to < 165°C as now proposed in the NASA

specification.) Since the objactive of this specification is

52
TABLE 18. COMPARISON OF WEIGHT LOSS MEASUREMENT PROCEDURES

C,o

Adhesive

Epo-Tek H20E

Ablebond 36-2

Epo-Tek H44

Ab|ebond 58-6

Epo-Tek H70E

Epo-Tek H77

Ablebond 4]-]

Ablefi|m 550

aCured 0.5 hour at |50°C

bcured 1.0 hour at ]50°C

CMethano| a|so present

dAmmonia a|so present

Weight Loss at 250°C (TGA)

(grams/gram x ]00)

0.8

0.0

0.0

0.0

I.5a(I.o)b

0.3

1.0

1.3

Water Vapor (MS)

__ ppm

<300

<300

<300

<300

4,477c,d

<300

22,545

2,883c, d

oo

i

r- m m
3.4.4

to establish such parametric data, it is recommended that both

tests be retained in the specification and that MS limits be

established for ammonia, methanol, and other outgassed materials

which may be detrimental. Until calibration procedures are

established, however, these limits will have to be set as reference values only. The test facility will be required to record

and report interpreted scan data over the mass range of 2 to I00.

This will allow the procuring activity and manufacturer to establish acceptance levels.

BOND SHEAR STRENGTH TESTS

Bond shear tests were cenducted using semiconductor die,

chip capacitors, and ceramic chips (to represent substrate attachment) as shown in Table 19. Five devices of each type were shear

tested under five different conditions as follows:

I. At 25°C

2. At 150oc

3. At 25°C after solvent immersion

4. At 25°C after 200 cycles from -65°C to 150oc

5. At 25°C after I000 hours at 150°C

The solvent immersion test consisted of consecutively immersing the test specimens for one-half hour each in isopropyl alcohol,

a solution of 50 vol percent methylene chloride in trichlorotrifiuoroethane and in I00 percent trichlorotrifluoroethane. The specimens were allowed to dry for a minimum of three hours prior to

shear testing. Temperature cycling was perfoFmed in accordance

with MIL-STD-883B, Method 1010.4, Test Condition C.

Test specimens representative of those used for semiconductor (transistor) die testing are shown in Figures 29 and 30. Five

die each, bonded with two adhesives, are contained on each substrate. Test specimens used for capacitor shear testing are shown

in Figures 31 and 32, and a substrate shear test specimen is shown

in Figure 33. Package lids were used as substitutes for the package

base in the latter case.

54
TABLE19. DEVICESANDSUBSTRATESSELECTEDFORBONDSHEARTESTS

Device Type

Transistor

Trans i s tot

Capacitor

Capacitor

Substrate Chip

tact

Metallization

Alloyed Gold

Alloyed Gold

Silver

Silver

None

Size (cm)

0.051 x 0.051

0.]02 x 0.102

0.127 x 0,102 x

0.102

0.699 x 0.216 x

0.152

0.127 x 0.127 x

O. O38

Weight (Kg) a

1.0 x 10-7

6.5 x 10-7

4.2 x lO-6

1.34 x 10-4

2.3 x 10-6

Substrate

99.5% Alumina

99.5% Alumina

99.5% Alumina

96% Alumina

Kovar

Metallization

Gold Thin Film

Gold Thin Film

Gold Thin Film

Gold Thick Film

Plated Gold

aAverage of ten devices in each case. O0

"n:II i

"o_'}

_r0'_

_Q

c'- rrl
ORIGINAL PAGE

BI:ACK AND WHITE P' ,_TOGRAPH"

•;: :.;;;; ;::::::::::::::::;:; ::::::::::::::::::::::::::: ==========================================: ::;::::::::.:;:;:_:.::::::.:.:.,:::::: ::;:;:::::::::::::::::::::::: :::.::::::::::::::::::::::::;: ;:::.: .>.:.::.:,,,:..:,:.::,.:•,::.::.:: :.:: ::: :::::::.:.:::.::::::::::::.:::

: ...:.:'_..... •.:.:.:, .:.,,, .:+.::,::•.:;:.:::,:.,,::,:.:,.:.:.::::::,:....;.,,:,:,:.:,.,,,, <,>. +..., ..:;::::: ........ :..:::::::::::::::::::::::::::::::::::: .:,:::..:,,.. :.::::::::.:.:::;:::::;:. ::;:::::..:>:;::: :..:.:.:.:.,.._;.:;;;.,,,.,•...:,,

• ..... :,... t:.:,;, ,::,.:, :._ .,.- ...: .,.,:,:...: • : :..:+:,,.......,., ....<.: •,.:+ >,.,.:, ::,::::_::::ii i:::i:!:::::::i::::':::::: :::i i::::::::i:::::::!:!:::::::::::::::::::::::::: .. ::::

:::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: '.:i:

: :. ============================= . ============================== ::::::::::::::::::::::::::::::::::::::::::::::_:_::_:::::_:::::::::::::::_::_:::::::::::::::::::::::::::::_::::::::::::::::::: ::::::::::::::::::::::::::::::::::::>: ..:::

Figure 29. Small Semiconductor Die Shear Test Specimen

Figure 30. Large Semiconductor Die Shear Test Specimen

56
ORIGINAL PAGE

BLACK AN,'3. ',^'HITE PNOTF)_P, AP!-[

Figure 3], Small Capacitor Shear Test Specimen

<::::::::::,:::::::::::::::::::::::::,:::::::::::::::::::: ::........

Figure 32. Large Capacitor Shear Test Specimen

57
ORIGINAl PAG_'

__,-_,.,K ,AND WHITE PHOTOGRAPI_{

Figure 33. Substrate Shear Test Specimen

58
All substrates were cleaned prior to bonding by scrubbing

consecutively in deionized water, isopropyl alcohol, and trichlorotrifluoroethane followed by rinsing with clean trichlorotrifluoroethane and blowing dry with dry nitrogen. All filleting

was removed from around the semiconductor die and substrate chips

prior to cure. The fillets were not removed from the capacitors,

however, and only the minimal amount of adhesive was used (see

Figure 32) to obtain a worst case shear condition.

The results of the shear tests are shown in Tables 20 through

24 and Figures 34 through 38. The NASA specification requires a

bond strength > IOS calculated using the following equation with

a minimum requirement of 6.9 x 106 newtons/meter 2 (I000 psi):

S = 9.8Wa

A

where: S = bond strength (newtons/meter 2)

W = weight of device or substrate expressed

in kilograms

a = constant acceleration requirement per

MIL-STD-883, Method 2001 in Gs

A = bond area expressed in square meters

9.8 = gravitational constant expressed in

meters/second 2

The calculated bond strength requirement for each of the

devices used, assuming a constant acceleration requirement of

20,000 Gs, is included in the tables and in the figures. In

the case of the transistors, all of the electrically conductive

adhesives met the calculated requirements (Tables 20 and 21 and

Figures 34 and 35) but Epo-Tek H20E showed an average shear

strength of 5.3 meganewtons/meter 2 (750 psi) at 150°C for the

0.102 x 0.102 cm transistors failing the minimum requirement of

6.9 meganewtons/meter 2 (I000 psi).

In the case of the electrically insulative adhesives used

59
C_

TABLE 20. COMPARISON OF BOND SHEAR STRENGTH RESULTS FOR SMALL TRANSISTORS (0.051 x 0.051 cm)

Adhesi ve

Ablebond 36-2

Average

Epo-lek ii20E

Average

Ablebond 58-6

Average

At 25°C

N MN/.I2 PSl

12 47 6900

15 56 8100

13 52 7500

18 69 I0000

12 47 6900

14 54 7900

12 47 690O

16 60 8800

13 52 7500

20 77 11300

16 60 8800

15 59 8600

5.6 22 3100

8.9 34 5000

7.8 30 4400

13 52 7500

11 43 6300

9.3 36 5300

Epo-Tek tt44

Average

abased on an acceleration of

7.8 30 4400

13 52 7500

8.9 34 5000

6.7 26 3800

II 43 6300

9.6 37 5400

At 150°C

N MN/m 2 PSI

6.7 26 3800

8.9 34 5000

8.9 34 5000

5.6 22 3100

4.4 17 2500

6.9 27

1.1 4 600

2.2 9 1300

2.2 9 1300

2.2 9 1300

2.2 9 1300

2.0 8 II00

5.6 22 3100

3.3 13 1900

3.3 13 1900

4.4 ll 25OO

4.4 17 2500

4.2 16 24O0

3.3 13 1900

4.4 17 250O

I_ 43 6300 .4 17 2500

7.8 30 4400

Shear Strength

At 25°C

After Solvent

Immersion

N MNIm 2 PSl

18 69 I0000

21 81 11700

20 77 11200

22 85 12300

8.9 34 4900

18 69 10000

II 42 6100

20 77 I1200

14 54 7800

16 62 9000

8.9 34 4900

14 54 7800

13 50 7300

11 42 6100

7.8 30 4400

22 85 12300

20 77 I1200

15 57

At 25°C

After 200

Temp Cycles

N MN/m2 PSl

14 54 7800

20 77 11200

12 46 6700

4.5 17 2500

13 50 7300

T3 50 7300

5.6 22 3200

II 42 6100

16 62 9O00

17 65 9400

12 46 6700

12 46 6700

5.6 22 3200

8.9 34 4900

4.5 17 2500

7.8 30 4400

II 42 6100

29

3.3 13 1900

17 65 9400

8.9 34 4900

5.6 22 3200

I0 38 5500

At 25°C

After I000 hr

At 150°C

N MNIn_ PSI

16 60 8800

10 39 56O0

29 111 16000

12 47 6900

16 60 8800

64 9300

17 64 9400

21 81 11900

17 64 9400

5.6 22 3100

36 137 20000

19 73

18 68 I0000

12 47 6900

8.9 34 5000

5.6 22 3100

II 47 6300

II 47

Calculated

Requirement a

N MN/m 2 PSI

0.20 0.75

0.20 0.75

0.20 0.75

8.9 34 5000

7.8 30 4400

8.9 34 5000

14 54 7800

11 42 6100

6.2 24 3500 I0 39 5700 8.9 34 4400

13 51 7500

15 56 8100

12 47 6900

12 47 690O

12 47 69O0

13 50 7300

0.2(3 Q.75

llO

II0

llO

II0

20,000 Gs

O0

"m6_

E_

rm
Ch

...J

TABLE 21

Adhesive

Abl ebond 36-2

Average

Epo-Tek II20E

Average

Ablebond 58-6

Average

Epo-Tek 1144

Average

COMPARISON OF BOND SHEAR STRENGTH RESULTS FOR INTERMEDIATE SIZE TRANSISTORS (0.I02x 0.I02 cm)

At 25°C

N MNAIi2 PSI

At 150°C

N MNAn2 PSl

27 26 3800

II II 1600

17 17 2500

31 3O 4400

22 21 3000

2-T 21 3-006

5.66 780

6.77 940

5.66 780

4.44 630

4.44 630

-_.3B

8.99 1300

19 18 2600

25 24 3500

11 11 1600

16 16 2300

27 26 3800

22 21 3O00

62 60 8700

62 60 8700

53 51 7400 _ _ 6-TC6

13 12 1700

22 21 3000

36 35 5100

45 42 6100

36 35 5100

T_ 4-_

67 65 9400

53 51 7400

45 44 6400

8.9 8.6 1200

22 21 3000

3-g-- 38 5500

22 21 30OO

45 44 6400

22 21 3000

18 17 2500

18 17 2500 g 24 3500

T6 16 2300

45 44 6400

18 17 2500

30 29 4200

23 22 3200

28 27 3900

29 28 4100

aBased on an acceleration of 20,000 Gs

Shear Strength

At 25°C

After Solvent

I_nersion

N MN/m2 PSI

31 30 44OO

27 26 3800

18 17 2500

27 26 3800

36 35 5100

28 27

22 21 3100

31 30 4400

22 21 3100

22 21 3000

45 44 6400

36 35 5100

53 51 7400

31 30 4400

89 86 12000

53 51_ 7400

52 50 7300

49 48 7000

22 2l 3000

18 17 2500

27 26 3800

22 21 3000

28 27 3900

At 25°C

After 200

Temp Cycles

N MN/m2 PSl

]6 16 2300

42 41 5900

41 40 5800

51 50 7300

28 27 3900

3-_ 5-_

75 73 I0600

27 26 3800

13 12 1700

34 33 4800

67 65 9400

31 30 4400

17 16 2300

50 49 7100

45 44 6400

19 18 2600

3_

34 33 4800

29 28 4100

28 27 3900

19 18 2600

23 22 3200

27 26 3800

At 25°C

After I000 hrs"

At 150°C N MN/m 2 PSI

53 51 7400

18 17 2500

45 44 64O0

36 35 5100

49 48 7000

4_ 44

46 45 6500

61 59 8600

42 41 59O0

31 30 4400

45 44 6400 _ 6200

24 23 3300

48 47 6800

72 70 lOlO0

77 75 10900

71 69 10000

5-8 56 8100

50 49 7100

45 44 6400

30 29 4200

22 21 3000

45 44 6400

38 37 5400

Calculated

Requirementa

N MN/m2 PSI

1.3 1.2 180

1.3 1.2 180

1.3 1.2 180

1.3 1.2 180

O0

"oG)

:I)p

_M
r-J

TABLE 22. COMPARISON OF BOND SHEAR STRENGTH RESULTS FOR SUBSTRATE CHIPS (0.i27 x 0.127 x 0.038 cm)

At 25%

Adhesive N MNIn_ PSI

Epo-Tek II70E

At 150°C

N MN/m 2 PSI

8.9 5.6 809

2.2 1.4 200

5.6 3.5 500

4.5 2.8 400

4.5 2.8 400

5.3 3.3 500

ll.l 6.9 I000

7.8 4.9 700

6.7 4.2 600

4.5 2.8 400

5.6 3.5 500

7.1 4.4 600

13.4 8.4 1200

8.9 5.6 800

13.4 8.4 1200

17.8 II 1600

26.7 17 2500

16.0 I0 1500

8.9 5.6 800

2.2 1.4 200

5.6 3.5 500

5.6 3.5 500

5.6 3.5 5O0

5.6 3.5 500

62 39 5700

49 31 4500

45 28 4100

62 39 5700

58 36 5200

Average 55 34 4900

138 86 12500

134 84 12200

Epo-]ek f177 116 73 I0600

Ill 69 10000

Ill 69 lO000

Average i22 7-6- llOO0

89 56 8100

7] 44 6400

Ablebond 41-1 Ill 69 IO000

134 84 12200

IO7 67 9700

Average 102 64 9300

134 84 12200

I02 64 9300

Ablefilm 550 7l 44 6400

80 50 7300

138 86 12500

Average 105 66 9600

.....................................

Shear Streflgth

At 25°C

After Solvent

Immersion

N MN/m 2 PSI

49 31 4500

49 31 4500

76 48 7000

53 33 4800

45 28 6500

54 34 49O0

80 50 7300

67 42 6100

27 17 2500

53 33 4800

71 44 6400

60 38 550O

67 42 6100

89 56 8100

134 84 12200

Ill 69 lO000

62 39 5700

93 58 8400

89 56 8100

58 36 5200

89 56 8100

80 50 7300

98 61 8800

83 52 7500

At 25°C

After 200

Temp Cycles

N MNIm 2 PSl

89 56 8100

71 44 6400

89 56 8100

I02 64 9300

80 50 7300

86 54 78O0

134 84 12200

53 33 48O0

129 81 ll7OO

134 84 12200

85 53 7700

I07 67 9700

102 64 9300

89 56 8100

142 89 12900

89 56 8100

85 53 770O

lOl 63 9100

129 81 11700

lll 69 lO000

53 33 4800

62 39 5700

76 48 7000

86 54 7800

At 25_C

After 1000 hrs

At 150°C

N MN/m 2 PSI

156 98 14200

160 IO0 145OO

80 50 7300

151 94 13600

98 61 8800

129 81 If700

22 14

31 19

8.9 5.6

45 28

71 44

36 23

107 67

58 36

53 33

142 89

102 64

93 58

53 33

125 78

Ill 69

93 58

80 50

93 58

aBased on an acceleration of 20,000 Gs

Calculated

Requiremen_

N MNIm z PSI

4.6 2.8 400

2000

2800

800 4.6 2.8 400

4100

6400

_Too

9700

5200

4800 4.6 2.8 4001

12900

9300

8400

4800

113[10

10000 4.6 2.8 400

8400

7300

8400

O0

C7_
TABLE 23. COMPARISON OF BOND SHEAR STRE_!GTHRESULTS FOR SMALL CAPACITORS (0.127 x 0.102 x 0.102 cm)

(_

(._

Adhes ive

Ablebond 36-2

Average

At 25_C

N M/Nm2 PSI

16 12 1700

19 15 22O0

16 12 1700

21 16 2300

16 12 1700

I-7- _ 1900

Epo-Tek 1120E

Average

Ablebond 58-6

Average

Epo-Tek tt44

Average

11 8;'5 1200

13 I0 1500

18 14 2000

15 12 1700

15 12 1700

liT l-- 16oo

22 17 2500

23 18 2600

27 21 3000

22 17 2500

32 25 3600

_Tg

At 150%

MN/m2 PSI

6.7 5.2 750

2 9.2 1300

6.7 5.2 750

2 9.2 1300

18 14 2000

3.3 2.5 360

2.2 1.7 250

3.3 2.5 360

8.9 6.8 99O

2.2 1.7 25O

3.-TT 45--6

27 21 3000

-- ._ ----b

30 23 3300

26 20 2900

21 16 2300

t_'C 2-gO-(

5.6 4.3 620

6.7 5.2 750

4.4 3.4 490

6.7 5.2 750

6.7 5.2 750

BT-.-_6_ 6-T_

23 18 2600

13 I0 1500

12 9.2 1300

17 13 1900

20 15 2200

i-% I-T TC_

Shear Strength (NewtuBs)

At 25°C

After Solvent

Inmler%ion

MN/m_ PSII

14 II 1600

28 22 3200

22 17 2500

31 24 3500

9 15 2200

_-_ T_ 26OO

4 II 1600

21 16 2300

19 15 2200

3 I0 1500

14 II 1600

l-B- " _ 1700

17 13 1900

14 11 1600

26 20 2900

22 17 2500

20 15 2200

_T 1"5"

32 25 3600

31 24 3500

45 35 5100!

22 17 2500 _

27 21 30O0

2-T 3-_

At 25°C

After 200

Temp C#cI es

N MN/m_, PSI

4.5 3.5 50C

6.7 5.2 75C

4.5 3.5 50£

8.9 1.8 lOOC

17.8 1.4 200(

8._ 6.-_ -_

16 12 170(

12 9.2 130C

I0 7.7 IIOC

8.9 6.8 IOOC

28 22 320C

15 _

19 15 2200

18 14 2000

19 15 220O

24 18 2600

30 23 3300

_Z TT 7-gO_

17 13 1900

23 18 2600

13 I0 1500

II 8_5 1200

23 18 2600

I-_ I-4- 2-66O

At 25°C Calculated

After 1000 Mrs

At 150_C Requir#ment a

N MN/m Z PS]N MN/m _ PSI

II 8.5 1200

12 9.2 1300

17 13 1900

19 15 2200

17 13 1900

i-g T_ 17oo

12 9.2 1300

45 35 5100

15 12 1700

17 13 1900

16 12 1700

2-T TB-- 7_0-6

17 13 1900

27 21 3000

13 I0 1500

21 16 2300

32 25 3100

_Z TT 7TO_

28 22 3200

17 13 1900

18 14 2000

16 12 1700

29 22 . 3200

2-T l-T

3.2 6.3 910

B.2 6.3 910

B.2 6.3 910

8.2 6.3 910

a Based on acceleration of 20,O00Gs

b Device lost in handling

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0098 _'LL 892

00S8 _'LL 89_

0098 g'L[ 89_

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3oS7 lV

(m3 8S['0 x 9L8"0 x 669"0) SaOII3VdV3 39aVl BOJ SIq_S3B HI9N3alS _V3HS GNO_ 30 NOSIaVdWO3 "#8 3lBVl

a6eaaA V

bMl _al-od_

O6_JOA v

9-89 pu0qa[qv

aB_Ja^ V

3081t _al-od3

a^!saqpv

M:)
r_

v

Cn

cQJ

C_

OJ

c12,000

I0,000

8,000

6,000

4,000

2,000

A - Ablebond 36-2

B - Epo-Tek H20E

C - Ablebond 58-6

D - Epo-Tek H44

..... Calculated Requirement

n

m

A B CID

m

i

At 25°C

r=.-,

i

| .

At 150°C

A

m

m

BIC D

After Sol vent

Immers i on

m

n

i

A B CD

I

I

i

After Tem

Cycle

).

m

m

i

A B C!D

! -

i

!

I

; i

.... i--

After 1000

hrs. @ 150°C

- 82.8

- 69.0

- 55.2

41.4

27.6

13.8

Z

O0

O_

_r"

r-r,_

Figure34" Comparison of Bond Shear Strength Results for Small Transistors (0.051 x 0.051 cm)
r_

v

_J

r_v

c12,000

I0,000

8,000

6,000

4,000

2,000

A - Ablebond 36-2

B - Epo-Tek H20E

C - Ablebond 58-6

D - Epo-Tek H44

...... Calculated Requirement

I u

i

i

A!B C D I

.-I !i! '_

__ ' .

At 25°C

Figure 35.

"-I

i

I

J

I

i

I

!

I

AI

I

I

 _Ic

T-FI

iAiBlC D

After Solvent

Immersion

! i

D !!

-L

I

I

A B CD

i

I

!

I

-- _ _-._- - _ _

_ m

....

I

i

I

. i

A Btc DI

1

iltil-ILLI 

At 150°C After Temp. After I000

Cycle hrs. @ 150°C

Comparison of Bond Shear Strength Results for Intermediate

Size Transistors (0.102 x 0.102 cm)

82.8

69.0

55.2

C_J

E

41.4

27.6

13.8

O0

m

0

;7

0"_.

C: ).5,

J- ra_
(_

-.j

12,000 --

lO,O00 --

_ .

v

8,000 --

6,000 _--

0

4,000 --

2,000

m

m •

A BC D

At 25°C

A - Epo-Tek H70E

B - Epo-Tek H77

C - Ablebond 41-I

D - Ablefilm 550

Calculated Requirement

J

i

i

I

i

D

m

After Solvent

Immersion

A B C

.... .....I

At 150°C

m

A B CID

I

I

After Temp

Cycle

-- 69.0

J

I

I

Ii

!

ABCD I

' i

I

I J

After 1000

hrs. @ 150°C

-_ 55.2

E

41.4

oo

o_

Figure 36. Comparison of Bond Shear Strength Results for Substrate Chips

(0.127 x 0.127 x 0.038 cm)
3500 J 24.1

Go

c/)

Ci.

v

cc4-)

Cr)

scc_

3000

2500

2000

1500

IOO0

5OO

I

m

-LI

I

•! •

, I

I

• - --I m -- ,

I

A 81C D

I

I

I

,i

!

At 25°I

A - Ablebond 36-2

B - Epo-Tek H20E

C - Ablebond 58-6

D - Epo-Tek H44

Calculated Requirement

r

i

I

-,,,,,,,.-4

I

ABIC _D

!

At 150°C

"=I

I

I

II

f

FI!

I

i,

I

!AIBc

!

I

After Sol vent

Inlmer s i on

AB CD

After Temp.

Cycle

w

i

i

I

i

i

I

AB C

20.7

u 17.2

13.8

Figure 37. Comparison of Bond Shear Strength Results for Small Capacitors

(0,127 x 0.102 x 0.102 cm)

6.90

I

i

I

OJ

E

...... j

After 1000

hrs. @ 150°C

3.59

O0

o_

0 "_

F" r:_1

CQ
C_

C_.

v

c-

(--

C_

m_

c3000 _

A - Ablebond 36-2

B - Epo-Tek H20E

C - Ablebond 58-6

D - Epo-Tek H44

2500 ........................................ Cal cu]a%e_ _Re_q_Li r_e_iellt_

2000

1500

i000

5OO

i

|

ClD.

I .

At 25°C

Figure 38.

At 150°C

m

i

A BCD:

After Sol vent

Imme rs i on

After Temp.

Cycle

After 1000

hrs. @ 150°C

Comparison of Bond Shear Strength Results for Large Capacitors

(0.699 x 0.216 x 0.152 cm)

_20.7

_ _ _17.2

_13.8

10.4

_ 6.90

3.45

C_E

O0

"0_

_Jr

_ _.;_

r- l_;'l
ORIG!NAL PAGE IS

OF POOR QUALFrY

to bond the substrate chips, Table 22 and Figure 36, all of the

adhesives met the calculated requirement of 2.8 meganewtons/meter 2

but Epo-Tek H70E and H77 and Ablefilm 550 failed to meet the minimum requirement of 6.9 meganewtons/meter 2 when tested at 150°C.

With the exception of Ablebond 36-2, Tables 20 and 21 and

Figures 34 and 35, the electrically conductive adhesives showed

little or no loss in bond strength following solvent immersion,

temperature cycling, and I000 hour storage at 150°C. (The results for Ablebond 36-2 after solvent immersion are difficult to

explain since the values for the 0.051 x 0.051 cm transistors were

quite high while those for the larger 0.102 x 0.102 cm transistors

which should have been more resiszant to solvent immersion were

low. A possible explanation is that the solvents were retained

longer in the adhesive under the larger transistors.) _ne eiectrically insulative adhesives (Table 22 and Figure 36) also

showed little or no change with the exception of Epo-Tek H77

which showed a 50 percent loss in strength after solvent immersion

and a 70 percent loss after I000 hours at 150°C.

Based on these results, it can be seen that the equation

used to calculate the bond strength requirement for semiconductors

and substrates has little meaning since the adhesives greatly exceed the calculated requirement in all cases except at 150°C. The

bond strength requirement will therefore be changed to require a

minimum strength of 6.9 x 106 newtons/meter 2 (I000 psi) when measured at 25°C. In all subsequent tests the requirement will be

based on the initial bond strength with the exception of the requirement at 150°C. This latter requirement will be a minimum of

3.5 x 106 newtons/meter 2 or 500 psi. Using the data from Tables 20,

21 and 22, the requirements to be used for semiconductors and substrates are as follows:

Test or Condition

At 25°C

At 150oc

After immersion

After temp. cycling

Semi conductors

>6.9 r_,_I/m2 (I000 psi)

L_ 3.5 MN/m2 (500 psi)

> 0.7 initial

> 0.7 initial

After lOOO hrs. at 150oc > 0.8 initial

Substrates

__>6.9 MN/m2 (I000 psi)

>3.5 MN/m2 (500 psi)

>0.7 initial

>0.7 initial

> 0.8 initial

7O
ORI_;N_L _-_| _m _ PA_E: I_

OF POOR QUALITY

In the case of the capacitors, the bond strength per unit area is

difficult to calculate because the area actually bonded cannot be

measured readily and varies from capacitor to capacitor. It was therefore elected to use the entire bondable area of the capacitor (whether

bonded or not) in calculating the bond strength per area. The results

using this method of calculation are shown in Tables 23 and 24 and

Figures 37 and 38. In the case of the small capacitors, Epo-Tek H20E

and Ablebond 58-6 failed to meet both the calculated requirement of 6.3

meganewtons/m 2 and the minimum requirements at 150°C. In the case of

the large capacitors, all of the adhesives failed the calculated requirement of 17.3 meganewtons/m 2 (2500 psi) and while Ablebond 58-6 and

Epo-Tek H44 met the minimum requirement of 6.9 meganewtons/m 2 in several

of the tests, individual test results were scattered well above and

below this value.

The amount of adhesive used for bonding the capacitors is shown

in Figures 39 and 40. The sz_lall capacitors were bonded with adhesive

approximating the maximum allowable. The large capacitors were bonded

with approximately one-half the amount that could be used without risking

shorting. (The center of the capacitor or the entire capacitor if wire

bonded, could also be bonded with electrically insulative adhesive

increasing the available bonding area.) It should be noted that the

large capacitors are approximately 32 times heavier (Table 19) than the

small capacitors while the total available bond area increased only 12

times. Selection of the proper adhesive and method of bonding is therefore very important in the case of large capacitors.

Based on the above results the requirements to be used for

capacitors are as follows:

Test or Condition

At 25°C

At 150°C

At 25°C after immersion

At 25°C after temp. cycling

At 25°C after I000 hrs. at 150°C

Capacitors

> 10.3 x 106 N/M2 (1500psi)

> 5.2 x 106 N/M2 (750 psi)

> 0.7 initial

> 0.7 initial

> 0.8 initial

71
ORIGINAL: PAGE

BLACK AND WHITE PHOTOGRAPH

Figure 39. Small Capacitor Test Specimen Showing Bond Area Used

Figure 40. Large Capacitor Test Specimen Showing Bond Area Used

72
The requirements at 25°C and 150oc were increased over those for

the semiconductors and substrates to allow for the greater weight

per available bond area of the capacitors.

3.4.5 CORROSIVlTY TEST RESULTS

Small dots of the paste adhesives (already mixed if a two-part

adhesive) were applied to the aluminized side of a mylar film and

allowed to stand for 48 hours. The film adhesive was placed on the

aluminized side of the mylar film and warmed to 60 to 70oc on a hot

plate causing the B-staged epoxy to melt and adhere to the film

Five samples of each adhesive were tested. After 48 hours exposure

to room ambient, the adhesives (with the exception of the film adhesive) were removed from the film by washing with acetone and the

film examined for corrosion as evidenced by changes in the light

transmissibility. In the case of the film adhesive, the samples

were examined for changes around the periphery of the adhesive.

As shown in Table 25, Epo-Tek H44 was the only corrosive adhesive.

It completely removed the thin film aluminum from the mylar where

it was applied. The test was repeated using thin film aluminum

sputter deposited on glass slides with identical results.

3.4.6 VOLUME RESISTIVITY

3.4.6.1 ELECTRICALLY CONDUCTIVE ADHESIVES

The volume resistivity test specimens for the electrically conductive adhesives were prepared using a standard 1 inch by 3 inch

glass slide. The slides were cleaned with methanol and placed in

a jig (Figure 41) which served as a guide for applying two strips

of transparent tape 0.25 cm apart (Figure 42). Two thicknesses of

tape were used to provide an adhesive layer approximately 0.008 cm

thick. (It was found that the thicker layers of adhesive improved

the specimen to specimen reproducibility.) A drop of the adhesive

to be tested was placed between the strips and squeegeed using a

single edge razor blade held at an angle of 30 o to the slide to

73
TABLE25. CORROSIVITYTESTRESULTS

-.J

Adhesive

Ablebond 58-6

Epo-Tek H44

Fpo-Tek H20E

Ablebond 36-2

Epo-Tek H70E

Epo-Tek H77

Ablebond 41-I

Ablefilm 550

Type

Single component, gold filled,

electrically conductive

Single component, gold filled,

electrically conductive

Two component, silver filled,

electrically conductive

Single component, silver filled,

electrically conductive

Two component, nonconductive filler

Two component, nonconductive filler

Two component,, nonconductive filler

Glass supported film, nonconductive

Result

No evidence of corrosion

Aluminum completely

removed by corrosion

under adhesive

No evidence of corrosion

No evidence of corrosion

O0

No evidence of corrosion c.

_r- _)

No evidence of corrosion

No evidence of corrosion

No evidence of corrosion
ORiG h",_AL pA @r"

.BLACK AND WHITE PHuTu,_RAPFt" m ""

Figure 41. Jig Used to Prepare Volume Resistivity Test Specimens

:_....:_::_{_i_{_{_{{_.._.i_i_!{i_{{i!ii_Ti_i_!;_ii!_;i!_`._:!_S?;_:_ii_:_:_i_:S_i_::_i_:_i_::::::::::::::::::::::::::::::::::::::::::::::::::: ...............

_i:i:!:_i:::::::::::::::::::::::::::::.>.i:i:1:!8i_i_:i_$_:F_:::_:i:i:_:._:_:i;::_:_:i:i:i:i:!:i:!:i:i:i:!_:i:i:i:i:i:i:i:i:i:i:i:i:i_i..i_i:i:i:_:_:!:_:_:_:_::::_:!:_:::_:.:i:_._:_`!_.. :.:

_:_:_:::_::.._ik: :_&':'::i:_.: :_ :_&:_iS. >.:: ;: :_:i::: _::: :i:_:::: :_:::::::::::::::::::::::::::::::::::::::::::::: :i:::!:::i:i i:i:Z:

:..1.:.:._>. • _... .:.:.:.:.;._:.>:._ _:_:_:_;_:_:_:_:_:_:_:_:_:_:_:_;_:_:_:_:_:_:_:.:_:_:. ,:.:.:.:...,: .:..:..:.

_!_?!_i_iii!ii:ii!i;_ii_:_.._:_!_!_i_iii_:..,....>:_iiiiii_iiiiiiii!_iii!_!ii_!i!i!iiiii:i!iiii_ii_iiiii_ii_ii_iiiii_::_:_i_:_:: ::::' :::l

•_ii!iiIi_4I_iiiii_i_!i_!!_!i!!i!ii!i!i!i_iiiii_ii_!i_1iii_iii_i!!!!ii_iii_i!i!_i!i!ii_1_i_i_i_;;iiiiii_i;i_i_i!_iii!!;i_i!!!_i_i_ii_;_i_i;!i!ii:i_

_......_,...._.>._..:..:.:,.>:..<......:...:.:.._&........ . : •

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: . ..-.

iiiiil;iiil;iiiii!iiiiiiii!!!iiiiiii!iiiiiiiiiiiii;!iiiiiiiiiii_ _"

i......................................... _:_:_:_:_:_:_:_;_ ....

ii_i_!ii_i_i!i_iii}ii_!!i_iiiiii_!!!!!i_!i____!!!__!__ii!i__i___iiiiiiiiiii!}!ii ::

ili!!!!;!_ii_!ii_iiiii;_?..i_i!iiii;!i!!!iiiiiii._iiiiili;!iiii!!ii!::_! 7

_iii;_iiiii':iiiiiii_!_N_iiiii':iiii;::;:,i::i::i::iii

.:i:i:i_iii _._!_._iiiiii_iiiiiiiil ;!!iiiiiiiiii iii__ii _:_ __i_i__iii.>.' _ii!;i_!ii!! ._iiii!iii;ii!!!iiii iii;iii!iiiii!iiiiiiii;!iill iZ Zi. ::

::::::::::::::::::::::: :!:i:i:!::!:i:i: ::_:_:!:.!:i:::_: :.'.':!:.",_:i: ::i::::_:F:::!:::i:!: :!81:8!:8 81::::::::::::::::::::::::::::::::::::::::::::: . : "

i!iIi_i_.._..._._._,_!!ii_i_ii_i!ii_::!!iii_ii_ii_i_iii_.>:.i_F,..._!i_ii_!_iiii_ii_i_iiiiiii_i:_i[i::iii:_::_::_ii::_::!i_::_:::::::: "71Z : .:.

_:!_1:_8!_.i_:i_:_:_:i:_:_.,..:_:_:_:`.._:_:i_!_!_...4.,.,._?._:_._._!:!8!_..,..1:_:_8i:!::8 ::i:i:i:!:i:!:!.:!8 !:i:i:i:F:i: i:.i8::iSi:i::::::"'::::":-'-::: - ........

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::. :...

Figure 42. Jig with Transparent Tape Applied as Mask on Glass Slide

75
form a strip at least 5.8 cm in length. The tape was removed

(Figure 43) and the adhesives were cured at 150°C for double

the time recommended by the manufacturer. Resistance measurements were made using a Kiethley 179TRMS Digital Multimeter,

a Hanson 6112A DC Power Supply and a General Radio 1432-M

Decade Resistor in conjunction with a four-point probe system.

A test fixture (Figure 44) with spring loaded contacts was used to

facilitate accurate measurements. The current contacts are

5.08 cm. apart and the voltage contacts are separated from

each current contact by 1.27 cm. The volume resistivity was

calculated using the following formula:

R (wxt)

P - 1

where p = volume resistivity in ohm-cm

R = measured resistance, ohms

w = width in centimeters

t = thickness in centimeters

1 = length between inner pair of probes

The MSFC-SPEC-592 requirement for volume resistivity for the

electrically conductive adhesives is < 0.001 ohm-cm at 25°C, 60°C,

150°C and at 25°C after I000 hours at 150°C. The results of the

tests performed on the four electrically conductive adhesives

(average of three specimen/adhesives)are shown in Table 26. Based

on these results, the requirement will be revised to <0.0005

for the silver-filled adhesives and _ 0.0015 for the gold-filled

adhesives.

3.4.6.2 ELECTRICALLY INSULATIVE ADHESIVES

The volume resistivity of the electrically insulative adhesives

was determined in accordance with ASTM D257 at 25°C. The results

are shown in Table 27. Based on these results the requirement at

25°C will be revised to >I x 1014 ohm-cm and the requirement at

125°C will be revised to_ 1 x 108 ohm-cm. These test specimens were

also used for the thermal conductivity, dielectric constant, and

dissipation factor measurements.

76
ORIGINAI_ PAGE

BLACK AND WHITE PHOTOGRAPH"

Figure 43. Jig with Test Specimen After Removal of Masking Tape

•.....• •....•••••••••H••••• •••••••.••••- .•••••• - ••,•••• •••HH •••

Figure 44. Test Fixture for Volume Resistivity Measurements

77
TABLE 26. RESULTS OF VOLUME RESISTIVITY TESTS

OF ELECTRICALLY CONDUCTIVE ADHESIVES

GO

Adhesive

Ablebond 36-2

Epo-Tek H20E

Ablebond 58-6

Epo-Tek H44

25°C

O,OO0167

0.000185

0.00105

0.000844

Volume Resistivity (Ohm-cm)

60°C

0.000181

0.000201

0,00115

0.000930

150°C

0.000214

0.000235

0.00146

0.00112

After I000 Hours

@ 150°C in N2

0.000108

0.000150

0.000795

0.000722
TABLE27. VOLUMERESISTIVITIESOFELECTRICALLYINSULATIVEADHESIVES

-.j

Adhesive

Ablebond 41-I

Epo-Tek H77

Epo-Tek H70E

Ablefilm 550

Specimen Specimen Volume Resistivity (ohm-cm)

Thickness Density

___cm) (g/cc) At 25°C At 125°C

0.5428 1.68 1.50 x 1014 2.28 x 108

0.3117 1.70 9.60 x 1014 3.93 x 108

0.3378 2.45 1.56 x 1014 5.70 x 108

0,4437 2.23 1.06 x 1014 1.08 x 109

0.2921 1.32 1,81 x 1014 2.60 x 109

Requirement

(ohm-cm)

1012

1012

)I012

1012

O0

O_

:X) p-
3.4.7

3.4.8

THERMAL CONDUCTIVITY

The thermal conductivity measurements were performed by

Geoscience Ltd.,Solana Beach, California using samples prepared

by Rockwell. The measurements were performed in accordance with

ASTM C518 using specimens 4.40 cm in diameter at the temperatures

specified in Table 28. As shown in Table 28, all of the adhesives

easily met the requirements. A plot Of the thermal conductivity

versus sample density is shown in Figure 45. It can be seen that the

thermal conductivity is proportional to the density in the case

of the electrically insulative adhesives but varies in the case

of the electrically conductive adhesives. (The Bakelite specimen

was used as a reference standard by the test laboratory.) Based

on these results the requirement will be increased to _5.0 x

I0-3 cal cm/cm 2 sec°C in the case of the electrically conductive

adhesives and to >l.OxlO -3 cal cm/cm 2 sec°C in the case of the

electrically insulative adhesives.

LINEAR THERMAL EXPANSION COEFFICIENT

The linear thermal expansion coefficients and glass transition

temperatures of the adhesives cured in accordance with Table 9 were

determined in accordance with ASTM D3381 using a DuPont Thermomechanical Analyzer (TMA). The analyseswere performed at Delsen Testing Laboratories Inc., Glendale, California over the temperature

range of -65 to 150°C at a heating rate of lO°C/minute in a nitrogen ambient. A repeat scan was performed on each specimen with

the exception of Epo-Tek H70E as shown in Table 29. As indicated

in the table, some problems were encountered in obtaining a well

defined glass transition temperature in all cases. The Epo-Tek

H70E also became too soft at 63°C to permit accurate measurements. The results in general indicate that the adhesives should

be cured for a longer period than that used (a minimum of twice

the manufacturer's recommended cure). A longer cure will increase

the glass transition temperature and also change the expansion

coefficients but all of the adhesives should still meet the

requirements shown in Table 29.

8O
TABLE28. THERMALCONDUCTIVITYTESTRESULTS

co

.--J

Specimen Specimen Measurement Thermal Conductivity Requirement

Thickness Densit_ Temperature Btu-ft _ g-cal-_m g-cal-cm

Adhesive (cm) (g/cm _) (oc) hr_ft r sec cm oc set cm2 oc

Ablebond 36-2 0.4186 3.48 119.4

Epo-Tek H20E 0.4056 3.44 120.5

Ablebond 58-6 0.4646 5.24 118.3

Epo-Tek H44 0.5070 5.51 117.2

Ablebond 41-I 0.5428 1.68 117.2

0.3117 1.70 121.1

Epo-Tek H77 0.3378 2.45 121.1

Epo-Tek H70E 0.4437 2.23 123.9

Ablefilm 550 0.2921 1.32 116.5

Bakelite 0.4890 1.31 115.6

2.05 0.00847 > 0.0035

1.50 0.00620 > 0.0035

1.93 0.00797 > 0.0035

2.28 0.00942 > 0.0035

0.58 0.00240 > 0.0004

0.65 0.00268 -

1.15 0.00475 > 0.0004

0.90 0.00372 > 0.0004

0.33 0.00136 _ 0.0004

0.30 0.00124 --

O0

:IJ r.

<)
ORIGINAL PAC_ _'_

OF POOR QUALITY

co

o

x

o

C,d

E

rj

09

E

u

%

u

i

v

":7

*r,-

-._

"o

¢..

o

e.,.-.

E

¢.-

F---

Rockwell International

IO .0

9.0

8.0

7.0

6.0

5.0

4.0

3.0

2.0

l.O

1.0 2.0

I

I

I

I

I

Density (g/cm 3)

Figure 45. Plot of Thermal Conductivity Versus Density

82
TABLE29. LINEARTHERrIALEXPANSIONCOEFFICIENTSANDGLASSTRANSITIONTEMPERATURES

GO

(.o

ADHESIVE

Epo-Tek H20E

Ablebond 36-2

Epo-Tek H44

Ablebond 58-6

Epo-Tek H70E

Epo-Tek H77

Ablebond 41-I

EXPANSION COEFFICIENT

BELOW TQ ABOVE _Tq

5.11 x lO-5(to 46°C) 2.11 x lO-4(above 59°C)

4.92 x 10-5 2.29 x I0 -_

.32 x 10-5 .47 x I0 -b

1.81 x 10-4

2 03 x 10-4

3.65 x lO-5(to 64°C) 1.12 x lO-4(above I18oC)

3.75 x 10-5 1 23 x 10-4

3.73 x lO-5(to 64°C)

4.00 x lO-5(to 75°C)

3.15 x lO-5(to 63°C)

1.18 x lO-4(above I04°C)

1.27 x lO-4(above I04°C)

2.54 x 10-5

2.46 x 10-5

9.74 x 10-5

1.02 x 10-4

3.04 x lO-5(to 65°C) 1.03 x 10 -4 (above I02°C)

3.20 x 10 -5 9.61 x 10-5

GLASS TRANSITION

(Tg °C)

Undefined

36

69

76

Undefined

88

Undefi ned

Unde fi ned

Specimen softened

at 63°C

62

64

Undefined

76

REQUIREMENT

< 6.5 x 10-5

be low Tg

<3,0 x 10-4

above Tg

o o

.0
ORIGINAL PAGE IS

OF POOR QUALITY'

3.4.9 IONIC IMPURITIES

Water extract analyses were performed on the cured adhesives to

determine the total ion content (electrical resistivity), hydrogen

ion content (pH), chloride ion, sodium ion and potassium ion contents.

Fed. Test Method Std. No. 406, Method 7071 was followed except that

the adhesives were cured directly in the Erlenmeyer flasks at 150°C

for double the length of time recommended by the manufacturer. The

pH of the water extracts were determined using an Orion Model pH

meter with a standard combination electrode. The sodium and potassium analyses were performed using atomic absorption and the chloride concentration was determined by measuring the turbidity of a

sample of the water extract to which silver nitrate has been added

in a Nessler tube. The result_ of the tests are shown in Table 30.

The ionic content in parts per million as sodium chloride was

calculated using the equation:

23.47 (L2 - LI) = parts per million as NaCl

Where L2 = specific conductance of sample (micromho/cm)

L1 = specific conductance of blank (micromho/cm)

W = weight of zample in grams

23.47 = grams NaCl/mho/cm

The factor 23.47 can be obtained experimentally or calculated

as follows:

A

Ls

Where: A

LS

= 23.47 gms NaCI in 50 ml water/mho/cm

= 1.4613 x lO-3g NaCI in 50 mil O.O005N NaCl

= 6.225 x 10-5 mho/cm (specific conductance of O.O005N NaCI)

The above equations assume that the samples are extracted with

50 cm3 of distilled water in accordance with Fed. Test Method STD. 406,

Method 7071.

84
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o 09SZ

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0£6Z

98

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mdd)_ua_uo3 3_uoI

O" t6_

0"£t16

&'L_L

£'LS

0"08

t1"_91.

B'tlg

(mdd)

L3

O0"L 0 O00'Sb

OZ'L 8"S£L O00=L[

_9"Z 6"LL O00=60L

£_'t 9"8£ O00'L[

00"0 £Z'£ O00'SBL

_'0 9"9£Z O00'SL

_S'O ZL'8 O00'Z9L

0"62 8"_£ O00'L£

(mdd) (mdd) (m3-mqo)

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£8"L

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9-8S puoqa[qv

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S3SAIVNV AIIBfldNI 31NOI 30 $I1_$3_ "0£ 318V1
3.4.10

ORIGINAL PAQ_ IS

OF POOR QUALITY

The specific resistivity is now used to control the total extractable ionic content of the adhesives. The ionic content as

calculated above will be substituted for the specific resistivity

and a maximum of lO00 ppm as NaCl (equivalent to a specific resistivity of approximately 43,000 ohm-cm) will be used as the

requirement.

Based upon the results in Table 30, the overall requirements

for control of the ionic content of the adhesives were selected as

follows:

Recommended Requirement

pH 4.0 to 9.0

Na(ppm) < 50

K(ppm) _ 5

Cl(ppm) < 300

lonic content (ppm as NaCI) < I000

Using these requirements and examining the results in Table 30, it

can be seen that the electrically conductive adhesives Ablebond 36-2

and Ablebond 58-6 are acceptable while Epo-Tek H20E is borderline

based on its ionic content and Epo-Tek H44 is unacceptable based

on pH, sodium content, and ionic content (Epo-Tek H44 also failed

the corrosivitiy test). In the case of the electrically insulative

adhesives, Epo-Tek H77 and Ablefilm 550 are acceptable while EpoTek H70E is unacceptable because of its ionic content and Ablebond

41-1 is unacceptable because of sodium, chloride and ionic contents.

Dielectric Constant and Dissipation Factor

The dielectric constants and dissipation factors for the electrically insulative adhesives were determined at IKHz and IMHz

at 25°C in accordance with ASTM Dl50. The results of the dielectric

constant measurements are given in Table 31.

86
IF_ ,_,_'_ _ 'm _ _

TABLE 31. RESULTS OF DIELECTRIC CONSTANT MEASUREMENTS

Dielectric Constant

Adhesive 1 KHz 1MHz

Ablebond 41-I 6.06 a

5.91 b

Epo-Tek 5.98

Epo-Tek H70E 5.67

Ablefilm 550 4.25

aDensity = 1.68 g/cm 3

Requirement

-- < 6

5.72

5.84 "

5.47 "

3.92 "

bDensity = 1.70 g/cm 3

All of the adhesives met the dielectric constant requirement of

6. The lower density Ablebond 41-I specimen failed with a value

of 6.06. This specimen contained more voids than the higher density

specimen.

The results of the dissipation factor measurements are given

in Table 32.

TABLE 32. RESULTS OF DISSIPATION FACTOR MEASUREMENTS

Dissipation Factor Requirement

Adhesive 1 KHz 1MHz 1 KHz 1MHz

Ablebond 41-I O.0210a -- < 0.003 < 0.03

0.0205 b 0.025 - -

Epo-Tek H77 0.0051 0.013 " "

Epo-Tek H70E 0.0061 0.019 " "

Ablefilm 550 0.0124 0.045 " "

aDensity = 1,68 g/cm 3 bDensity = 1,70 g/cm 3

It can be seen that none of the adhesives pass the requirement

at 1KHz of _ 0.003 and the Ablefilm 550 fails the <0.03 requirement at 1MHz. Based on these results, the requirement at 1KHz

will be revised to < 0.03 andthe requirement at 1MHz will be

revised to < 0.05.

87
3.5

3.6

TASK E SPECIFICATION REVISION

Based on the results of the above tests and the conclusions and

recommendations derived therefrom, MSFC-SPEC-592 was revised and rewritten into military specification format. The revised specification

is included as Appendix A to this report.

The specification requires both qualification of the material by

the supplier and qualification of the processes to be used in assembly

of the hybrid microcircuit by the user. This duo qualification was

believed to be essential to insure that the microcircuits will meet the

reliability required for space applications.

TASK F COST DATA FOR MATERIALS TESTING

An estimate of the cost fo_ qualification testing of electrically

conductive (Type I) and electrically insulative (Type II) adhesives is

given in Table 33. This estimate is based on Table V of the revised

specification contained in Appendix A.

The costs include an estimate of the labor hours plus material

dollars required to perform the tests. In some cases the labor hours,

material dollars and independent laboratory costs were combined as in

the estimated costs for testing outgassing, thermal conductivity, and

coefficient of expansion. If the labor cost is assumed to be $55 per

hour, the estimated cost for full qualification of a Type I adhesive is

$12,133 and full qualification of a Type II adhesive is $5,950. The

material cost of the adhesive was not included because this cost is

minor in the case of the electrically insulative adhesives and quite

variable in the case of the gold and silver filled adhesives due to the

fluctuation in the prices of the metal fillers.

88
TABLE 33, QUALIFICATION COST ESTIMATE

co

Test on Condition

Materials (4o5.1)

Pot Life (4,5,2)

Shelf Life (4,5,3)

Infrared Spectrum (4,5.4)

0utgassing (4,5.5.1)

(4°5,5,2)

Bond Shear Strength(4,5o6)

Group 1 & 2

Group 3

Corrosivity (4.5.7)

Vol, Resist,(4,5.8,1)

(4,5,8°2)

Thermal Conductivity(4,5,9)

Coef, of Expansion(4o5.10)

Electrical Stability(4.5,11)

Dielectric Constant(4,5,12)

I Dissipation Factor(4o5ol3)

lonic Content(4,5ol4)

Sequential Test(4o5ol5)

Total

Total @ $55/hour

Supplier

0°5 hrs

I, 0 hrs

29°0 hrs + $1485

2,0 hrs

$465

12o5 hrs + $150

Type I

User

29°0 + $150

2°0 hrs

$5oo

Type II

Supplier I

0°5 hrs

Io0 hrs

28,0 hrs + $1435

2,0 hrs

$465

11.o5 hrs + $75

User

2°5 + $500

2,0 hrs

1,0 hrs

14o0 hrs

$57o

$25o

12,5 hrs + $150

2,0 hrs

12 hrs

Io0 hrs

2°0 hrs

$57o

$25o

mNi

12.0 hrs

72 hrs + $2870

$6830

nm_

mwm

m_m

8 hrs + $400

65,5 hrs + $1700

$5303

2°0 hrs

2°0 hrs

12,0 hrs

62,0 hrs + $2795

$4205

mwB

$500

_mm

nmm

PUre

mmm

_mm

_mB

4°5 hrs + $250

9°0 hrs + $1250

$I 745

_-_ -_
4.0 CONCLUSIONS

As discussed in Paragraph 2.4, the intent of this study was to

develop parametric data to establish specification requirements for the

adhesives to be used in assembly of hybrid microcircuits for space

applications. No attempt was made, for example, to optimize the cures

from the standpoint of outgassing,or the amount of adhesive used for

bonding capacitors. These parameters were found to be the ones that

the adhesives most commonly failed. It is believed that the requirements

as now specified, however, are essential to the reliable performance of

microcircuits in space applications and that with some minor process

development, the majority of the adhesives will meet the requirements.

A comparison of the performance of the adhesives with the requirements of the proposed specification contained in Appendix A is given in

Table 34. It can be seen thatnone of the adhesives met all of the

requirements. However, development of the proper cure schedules should

permit the majority of the adhesives to meet the outgassing requirement

and improvements in bonding techniques should permit the use of adhesives for bonding all but the largest size capacitors. Three of the

adhesives failed the ionic content requirements and one was borderline

while one also failed the corrosivity test. Additional processing or

material changes may be required by tlle suppliers to meet these latter

requirements.

9O
_D

TABLE 34° COMPARISON OF ADHESIVE PERFORMANCEWITH PROPOSEDSPECIFICATION REQUIREMENTS

Specification

Requirements

Materials (3.2oi)

Pot Life (3°2°2)

Shelf Life (3°2.3)

Infrared Spectrum(3o2.4)

Outgassing (3°3.2)

Thermal Stability

Outgassed Materials

Bond Strength (3°3o3)

Group 1

Group 2

Group 3

Corrosivity (3°3.4)

Volume Resistivity(3.3o5)

Thermal Conductivity(3.3o6)

Coefficient Expansion(3o3o7

Electrical Stability(3o3.8)

Dielectric Constant(3.3o9)

Dissipation Factor(3.3olO)

lonic Content (3.3.11)

Sequential Test (3.3.12)

Adhesive

Ablebond Epo-Tek Ablebond Epo-Tek Ablebond Epo-Tek Epo-Tek Ablefilm

36-2 H20E 58-6 H44 41-I H70E H77 550

P P P P P P P P

II II II II II II II II

II II II II II II II II

II II II II II II II II

" F " " F F " F

II p II II II II II II

F P P P NA NA NA NA

NA NA NA NA P P F 0 0 p

F F F F NA NA NA "u _ NA

P P P " p m P 00_ P

,, ,, ,, p " ,, ,, _ ,,

_r _

II II II II II II II II

,0"o

,, ,, ,, ,, ,, ,, ,, _ :_, "

" " " " NA NA NA _ _ NA

NA NA NA NA P P p _ ._ p

II |l II n II II II _ _ II

P B P F F F " "

NP NP NP NP NP NP NP NP

P = Passed F = Failed NA = Not applicable B = Borderline NP - Not performed
5.0

ORIGINAL PAGE IS

OF POOR QUALITY

RECOMMENDATIONS

It is recommended that the specification prepared under this program

be released as a military specification. It is also recommended that

the cure schedules used for the adhesives be further evaluated to reduce

the amount of potentially harmful outgassing. This outgassing may not

only cause contamination and corrosion of circuit elements but may also

be responsible for changes in the ohmic contact to semiconductor devices,

92
APPENDIXA

PROPOSED

NASA-MSFCSPECIFICATION

ADHESIVES, ORGANIC,SELECTIONAND

USEIN HYBRIDMICROCIRCUITS

1. SCOPE

1.1 Scope. This specification establishes the minimum requirements

for screening, qualification, acceptance, and performance of organic

adhesives for use in assembly of hybrid microcircuits for space applications.

Adhesive procurement requires a procurement specification describing the

detailed electrical, mechanical, chemical, and thermal requirements related

to the specific adhesive(s) to be procured. Use of these adhesives is

restricted to applications where the temperature after package sealing does

not exceed 150 C.

1.2 Classification. The adhesives shall be of the following types:

Type I - Electrically conductive

Type II - Electrically insulative

2. APPLICABLE DOCUMENTS

2.1 Issues of Documents. The following documents of the issue in

effect on the date of invitation for bids or request for proposal form a

part of this specification to the extent specified herein.

SPECIFICATIONS

MILITARY

MIL-C-45662 Cal i brati ng System Requirements

MIL-C-81302 Cleaning Compound Solvent,

Trichlorotrifluoroethane

MIL-M-38510 Microcircuits, General Specification

for

MIL-P-II6 Preservation, Methods of

93
2.1 Issues of Documents (continued)

STANDARDS

FEDERAL

FED-STD-406 Plastics, Methods of Testing

MILITARY

MIL-STD-129 Marking for Shipment and Storage

MIL-STD-202 Test Methods for Electronics and

Electrical Component Parts

MI L-STD-883 Test Methods and Procedures for

Microelectronics

(Copies of specifications, standards, and documents required by the contractor

in connection with specific procurement functions should be obtained from the

procuring activity or as directed by the contracting officer.)

2.2 Other Publications. The following documents form a part of this

specification to the extent specified herein. Unless otherwise indicated,

the issue in effect on the date of invitation for bids or request for proposal

shall apply.

AMERICAN SOCIETY FOR TESTING MATERIALS (ASTM)

ASTM C177 Thermal Conductivity of Materials by Means

of the Guarded Hot Plate, Test for

ASTM C518 Thermal Conductivity of Materials by Means

of the Heat Flow Meter, Test for

ASTM D150 AC Loss Characteristics and Dielectric

Constant (Permittivity) of Solid Electrical

Insulating Materials, Test for

ASTM D257 DC Resistance or Conductance of Insulating

Materials, Tests for

ASTM D3386 Coefficient of Linear Thermal Expansion of

Electrical Insulating Materials

ASTM D3850 Rapid Thermal Degradation of Solid Electrical

Insulating Materials by Thermogravimetric

Method, Test for

(Application for copies should be addressed to the American Society for Testing

and Materials, 1916 Race Street, Philadelphia, PA 19103.)

94
3. REQUIREMENTS

3.1 Adhesive Procurement Specifications. The hybrid microcircuit

manufacturer shall prepare a procurement specification(s) describing the

detailed electrical, mechanical, chemical, and thermal requirements related

to the specific adhesives which are to be procured. The requirements shall

not be less than those imposed by this specification but may be increased to

reflect the specific parameters of a particular adhesive or the requirements

of a particular application. The specific adhesive procurement specification(s)

governing its usage shall be submitted to the cognizant contracting officer for

review and approval.

3.2 Properties of Uncured Adhesive

3.2.1 Materials. The adhesive components and/or the adhesive shall be

of uniform consistency, free of lumps or foreign materials, and any filler

shall remain uniformly dispersed and suspended during the required pot life

(3.3.2), when inspected as specified in 4.5.1. The electrically conductive

fillers used in Type I adhesives shall be gold, or silver, or alloys of silver

or gold or other precious metals.

3.2.2 Pot life. The minimum pot-life period shall be one hour when

tested in accordance with 4.5.2. The adhesive shall be used within the

manufacturer's recommended pot-life period after removal from the container,

after mixing, or after thawing to room temperature in the case of premixed

frozen adhesives.

3.2.3 Shelf life. The shelf life of the adhesive shall be a minimum of

six months from date of receipt by the user when tested in accordance with

4.5.3. The shelf life is defined as the minimum time that the adhesive continues to meet the requirements of this test method when stored in accordance

with the supplier's instructions. The shelf-life expiration date shall be

affixed to the adhesive container by the supplier, and no adhesive shall be

used after that date.

3.2.4 Infrared spectrum. An infrared spectrum of the uncured adhesive

prepared for application, and of the individual components, if a two-component

system is used, shall be obtained in accordance with 4.5.4. The infrared

spectrum obtained during subsequent testing shall be identical. Any shift,

disappearance, or introduction of absorption bands throughout the specified

wavelength range (2.5 to 15 micrometers) of the spectrum for a subsequently

procured batch of adhesive shall be cause for rejection. Minor changes in

peak intensity are allowed. Changes in the infrared spectrum indicate changes

in the chemical composition of the adhesive and will require requalification

of the adhesive as a new material.

3.3 Properties of Cured Adhesive

95
3.3.1 Adhesive cure. The adhesive must be capable of meeting the

requirements of this document when cured according to the supplier's instructions but not exceeding a maximum temperature of 165oc for longer than four

hours. The cure schedule for the supplier tests (see 4.3 and 4.4) shall be

identical for all tests and shall be reported. The cure schedule for the

user tests shall be the minimum cure schedule and minimum vacuum bake

specified in the user's assembly document.

3.3.2 Outgassing. Outgassing of the cured adhesive shall not exceed

the values specified in Table I, determined in accordance with the test method

specified therein.

TABLE I. OUTGASSING REQUIREMENTS

Test Method

Test Requirement Paragraph

< 0.3% v:eight

-loss at 250 C

Thermal Stability

Outgassed Materials

Moisture

NH3 and amines

Alcohols

Ketones

Chlorinated

hydrocarbons

< 5000 ppm

Report presence

Report presence

Report presence

Report presence

4.5.5.1

Responsibility

Vendor

4.5.5.2 User

3.3.3 Bond shear strength. When tested as specified in 4.5.6, the

average bond shear strength of the test specimens shall meet or exceed that

specified in Table 11.

3.3.4 Corrosivity. The corrosive effects of adhesives on chip metallization shall be determined in accordance with 4.5.7. There shall be no change

in the light transmissibility of the aluminized Mylar in the areas where the

adhesive was applied.

3.3.5 Volume resistivity. When tested as specified in 4.5.8, the volume

resistivity shall meet the requirements as specified in:

Table III - Type I

Table IV - Type II

3.3.6 Thermal conductivity. When tested as specified in 4.5.9, the

thermal conductivity shall meet the requirements as specified in:

Table III - Type I

Table IV - Type II

3.3.7 Coefficient of linear thermal expansion. Nhen tested as specified

in 4.5.10, the coefficient of linear thermal expansion shall meet the requirements as specified in:

Table III - Type I

Table IV - Type II

96
TABLEII. BONDSHEARSTRENGTHREQUIREMENTS

BondShear Strength

Test or Condition

At 25 C

At 150 C

At 25 C after solvent immersion

At 25 C after temp

cycling

At 25 C after

1000 hrs at 150 C

Requirement (Newtons/meter2)

Semiconductors

_6.9 x I06a

>3.5 x 106

Substrates

>6.9 x 106

>3.5 x 106

Capacitors

>10.3 x 106_

>5.2 x 106

>0.7 Ib

>0.7 1

>0.8 1

->0.7 1

->0.7 1

->0.8 1

->0.7 1

->0.7 1

>0.8 1

Note a - Newtons/m 2 x 1.45 x 10-4 = Ibs/in. 2

Note b - I = Average initial bond strength found for the adhesive

at 25 C

Note e - Calculated assuming the entire base area of the capacitor

is bonded

97
TABLEIII. GENERALREQUIREMENTS FORELECTRICALLYCONDUCTIVEADHESIVES

O0

Test or Condition Unit____s Requirement

Volume resistivity ohm-cm Silver-filled Gold-filled

At 25 C <0.0005 <0.0015

At 60 C " "

At 150 C " "

At 25 C after I000 hrs at 150 C " "

Thermal conductivity

At 121 ± 5 C

Coefficient of linear thermal

expansion

Electrical stability

lonic Impurities

lonic content

pH

Chloride

Sodium

Potassium

cal cm >-5.0 x 10-3

cm2 sec°C

per deg C Below glass transition temperature

< 6.5 x 10 -5

Above glass transition temperature

(if less than 150 C)<3.0x I0 -.4

Resistances shall not increase more

than,5%

ppm (as NaCl)

ppm

ppm

ppm

-<1000

4.0 to 9.0

<300

-<5O

-<5

Test Method

Paragraph

4.5.8.1

4.5.9

4.5.10

4.5.11

4.5.14
TABLEIV. GENERALREQUIREMENTS FORELECTRICALLYINSULATIVEADHESIVES

Test or Condition

Volume resistivity

At 25 C

At 125 C

Thermal conductivity

At 121 _ 5 C

Coefficient of linear

thermal expansion

Dielectric constant

I kHz

I MHz

Dissipation factor

1 kHz

1 MHz

lonic impurities

lonic content

pH

Chloride

Sodium

Potassium

Units

ohm-cm

cal cm

Requirement

->1 x 1014

> 1 x 108

cm2 sec°C

deg C

>I.0 x 10-3

Below glass transition temperature

<6.5 x 10-5

Above glass transition temperature

(if less than 150 C) <3.0 x 10.4

<6.0

<6.0

<0.03

<0.05

ppm (as NaCl)

ppm

ppm

ppm

< 1000

4.0 to 9.0

-<300

< 50

<5

Test Method

Paragraph

4.5.8.2

4.5.9

4.5.10

4.5.12

4.5.13

4,5.14

0
Oi_iG_}'4AL PAG_ [_

OF POOR QUALITY

This requirement is limited to paste adhesives only. For film adhesives, the

expansion of the film in the X and Y directions may be assumed to be equivalent

to that of the glass supporting the film.

3.3.8 Electrical stability. When tested as specified in 4.5.11, the

electrical stability of the Type I adhesives shall meet the requirements

specified in Table III.

3.3.9 Dielectric constant. When tested as specified in 4.5.12, the

dielectric constant of the Type II adhesives shall meet the requirements

specified in Table IV.

3.3.10 Dissipation factor. When tested as specified in 4.5.13, the

dissipation factor of the Type II adhesives shall meet the requirements

specified in Table IV.

3.3.11 lonic impurities. When tested as specified in 4.5.14, the

ionic impurities shall not exceed that specified in Tables III and IV.

3.3.12 Sequential test environment. For those cases wilere resulting

microcircuits must meet MIL-M-38510 requirements, test specimens prepared

using the microelectronic adhesive in the application for which it is proposed shall withstand exposure to the test conditions specified in MIL-STD-883

as stated and modified in 4.5.14. After exposure to the complete sequence

of environmental conditions, the test specimens shall show no evidence of

mechanical degradation such as missing, loose or cracked capacitors, bond

fillet cracking, crazing or peeling, etc. The measured bond strength shall

meet the requirements at 25 C given in Table II. The measured bond resistance for the Type I adhesives shall be no greater than 0.3 ohm.

4. QUALITY ASSURANCE PROVISIONS

4.1 Responsibility for Inspection. Unless otherwise specified in the

contract or purchase order, the supplier and user are responsible for the

performance of all inspection requirements as specified herein. Except as

otherwise specified in the contract or order, the supplier and user may use

their own or any other facilities suitable for the performance of the inspection requirements specified herein, unless disapproved by the Government.

The Government reserves the right to perform any of the inspections set forth

in the specification where such inspections are deemed necessary to assure

that supplies and services conform to prescribed requirements.

4.1.1 Test equipment and inspection facilities. Test and measuring

equipment and inspection facilities of sufficient accuracy, quality, and

quantity to permit performance of the required inspection shall be established

and maintained by the supplier. The establishment and maintenance of a

calibration system to control the accuracy of the measuring and test equipment shall be in accordance with MIL-C-45662.

I00
4,1.2 Inspection conditions. Unless otherwise specified herein, all

inspection shall be performed in accordance with the test conditions specified

in the "General Requirements" of MIL-STD-202.

4.2 Classification of inspection. The inspection requirements specified

herein are classified as follows:

a. Qualification inspection (see 4.3)

b. Acceptance inspection (see 4.4)

4.3 Qualification inspection. Qualification inspection shall consist

of all tests to determine conformance with all requirements specified herein.

To insure that both the adhesive materials and the processes employing the

materials are controlled, both the supplier and the user of the adhesives

shall be responsible for performance of the inspection as designated in Table V.

4.3.1 Sample size. The number of samples to be subjected to each testing

procedure shall be as specified in the individual test methods.

4.3.2 Failures. Failure of any of the samples to meet the testing

requirements shall be cause for refusal to grant qualification approval.

4.3.3 Retention of qualification. To retain qualification, the material

shall be re-evaluated at 24-month intervals.

4.4 Acceptance testin 9. Acceptance tests shall be performed on each

lot and shall consist of the tests as specified in Table V.

4.4.1 Test lot. A test lot shall consist of all adhesive manufactured

under the same batch number.

4.4.2 Sample size. The number of samples to be subjected to each

testing procedure shall be as specified in the individual test methods.

4.5 Methods of examination and test

4.5.1 Materials. The adhesive components and/or system shall be examined

visually at a magnification of 30x to ensure conformance with the

requirements of 3.2.1.

4.5.2 Pot life. The parameters to be used in the measurement of pot

life (i.e., viscosity change, skin-over, loss of bond strength, etc.) are

generally material dependent. The vendor, with the concurrence of the

procuring activity, shall select the procedure to be used in establishing

and testing the pot life.

4.5.3 Shelf life. An unopened container of material shall be stored

under the conditions specified in 3.2.3. At the end of the shelf-life period,

the material shall meet the acceptance inspection requirements specified in

Table V.

I01
TABLE V. REQUIREMENTS FOR QUALIFICATION AND ACCEPTANCE TESTING

r_

Test or Condition

Materials (3.2.1)

Pot life (3.2.2)

Shelf life (3.2.3)

Infrared spectrum (3.2.4)

Outgassing (3.3.2)

Thermal stability

Outgassed materials

Bond shear strength (3.3.3)

Group 1 and 2

Group 3

Corrosivity (3.3.4)

Volume resistivity (3.3.5)

Thermal conductivity (3.3.6)

Coefficient of linear thermal

expansion (3.3.7)

Electrical stability (3.3.8)

Dielectric constant (3.3.9)

Dissipation factor (3.3.10)

Ionic content (3.3.11)

Sequential test environment

13.3.12)

Test Method

Paragraph

4.5.1

4.5.2

4.5.3

4.5.4

4.5.5

4.5.5.1

4.5.5.2

4.5.6

4.5.6

4.5.7

4.5.8

4.5.9

4.5.10

4.5.11

4.5.12

4.5.13

4.5.14

4.5.15

Responsibility

Qualification Acceptance

Supplier User Supplier User

R 0

R 0

R 0

R R

R 0

0 R

R 0

0 R

R 0

R

R

R

0

R

R I

0

R

0

R

R (at 25 C, R (at 25 C,

Type I only) Type I only)

R O

R 0

O R

R 0

.R 0

R 0

0 R

R I

R I

O

0

0

R'

R

O

0

R

0

R'

0

R

0

R (at 25 C,

Type I only)

0

0

R'

0

O

0

0

O0

C_

r" !,t

R = Required 0 = Optional R' = Skip lot frequency (2x per year or every

other lot, whichever is less frequent)
4.5.4 Infrared spectrum. An infrared spectrum shall be recorded over

the wavelength range of 2.5 to 15 micrometers of the uncured adhesive prepared

for application or of the individual components if a two-component system is

used. It will be necessary to separate the filler material from the resin in

order to obtain a good spectrum. This may be accomplished by using solvents

such as acetone for resin extraction or with a centrifuge. If a solvent is

used, it must be desorbed or blanked out before recording the spectrum.

4.5.5 Outgassin 9. The vendor shall be responsible for determining the

thermal stability of the adhesive when cured at the recommended time and

temperature (see 3.3.1). Unless otherwise specified, this same cure time

and temperature shall be used in preparing all adhesive test specimens. The

user shall be responsible for determining the identities and quantities of

the outgassed constituents when the adhesive is cured and subjected to vacuum

bake-out in accordance with his hybrid assembly process.

4.5.5.1 Thermal stability. The thermal stability of the material

shall be determined on three properly cured specimens (see 4.5.5) of

approximately I0 mg each in accordance with ASTM D3850. Tests shall be

performed by heating the specimens from room temperature to not less than

350 C at a heating rate not to exceed I0 C/minute in a nitrogen atmosphere

with 20 ml/minute nitrogen flow.

4.5.5.2 Outgassed materials. Test specimens shall be prepared using

gold-or nickel-plated Kovar packages of a configuration readily adaptable

to mass spectrometric analysis. If the adhesive is to be used for substrate

bonding, a substrate of proper size will be adhesively bonded in the package.

If the adhesive is to be used for device bonding, dummy or actual devices

sufficient to cover approximately 10 percent of the area of a substrate

normally used in the package shall be bonded directly to the package base.

The adhesive shall be cured using the minimum schedule and minimum vacuum

bake specified in the assembly drawing. The packages shall be hermetically

sealed in a dry box following vacuum bake, heated for 168 hours at 125 C,

and then subjected to gas ambient analysis in accordance with MIL-STD-883,

Method 1018. A minimum of three specimens shall be tested for each adhesive.

The proportion (by volume) of gases such as ammonia, alcohols, amines, ketones,

and other solvents shall be reported in addition to those specifically

identified in Method 1018.

I03
ORIGINAL ............

OF POOR QUi_L!T_;

4.5.6 Bond shear strength. The bond shear strength of the adhesive

shall be determined by using actual devices and substrate materials that will

be used in production. The devices may be functional rejects. The following

groups indicate the types of devices and substrates to be tested.

Group

l

Device

Semiconductors with gold

alloyed backing

Substrate

Thin- or thick-film goldmetallized alumina or goldplated Kovar

Substrate material Gold-plated Kovar and/or

nickel-plated Kovar

3 Capacitors Thin- or thick-film goldmetallized alumina

A minimum of five semiconductor devices with alloyed gold backing (die area of

16 x 10 -4 to 64 x 10 -4 in. 2) shall be selected for each of the Group 1 tests.

For the Group 2 tests, the substrate material shall be cut into chips 0.050

inch by 0.050 inch in size, and a minimum of five chips shall be used for each

test. The semiconductor chips may be bonded to either thin- or thick-film

gold-metallized alumina or gold-plated Kovar substrates. Bonding of the semiconductors and substrate materials shall be accomplished using the same

techniques as would be used in production except that no filleting shall be

allowed for specimens tested. For the Group 3 tests, the lightest and the

heaviest capacitors that will be used in production shall be selected for

test. Five capacitors of each size shall be used for each test. Bonding shall

be accomplished using the same techniques as would be used in production.

Filleting, as allowed in production for the capacitors, is permited. The

devices in each group shall be shear tested in accordance with MIL-STD-883,

Method 2019. Five devices from each group shall be tested at 25 C; at 150 C;

at 25 C after consecutive immersion for one-half hour each in isopropyl

alcohol, a solution of 50-volume-percent methylene chloride in trichorotrifluoroethane, and in I00 percent trichlorotrifluoroethane; at 25 C after I00

temperature cycles in accordance with MIL-STD-883, Method I010, Condition C;

and at 25 C after I000 hours at 150 C in a nitroqen ambient.

Following solvent immersion, the specimens shall be allowed to stand for a

minimum of four hours prior to shear testing. The vendor shall be responsible

for the performance of the Group l and 2 tests, and the user shall perform the

Group 3 tests.

4.5.7 Corrosivity

4.5.7.1 Paste adhesives. Smear a small sample of the uncured adhesive

(already mixed if it is a two-part adhesive) on the aluminum side of a sheet

of aluminized Mylar. Allow it to sit for 48 hours. Wash off the adhesive

with acetone and examine the light transmissibility of the aluminized Mylar

by holding the material to a light set!rce. Any change in light transmissibility in the areas where the adhesive was smeared indicates that the adhesive

has attacked the aluminum and will be grounds for failure. Five samples of

each adhesive shall be tested.

104
NOTE: The thickness of the aluminumon the Mylar should be kept to

a minimum,preferably approximately 50 to 75 angstroms.

Thicker aluminumcan be used, but it will be necessary to

let it sit longer.

4.5.7.2 Film adhesives. For film adhesives, it will be necessary to

cure a small sample of the adhesive on the aluminum side of the aluminized

Mylar used above. Again, allow it to sit for 48 hours, then examine the

light transmissibility of the samples. Unless the adhesive is transparent,

signs of corrosion will be most apparent around the periphery of the adhesive.

Any change in light transmissibility will be grounds for failure. Five

samples of each adhesive shall be tested.

4.5.8 Volume resistivity

4.5.8.1 Type I electrically conductive adhesive. Test specimens shall

be prepared using a standard l-inch-x-3-inch glass slide. A jig capable of

holding this slide, with two scribed lines I00 mils apart and parallel to

the length, shall be the guide for applying two strips of transparent tape.

Make sure there are no wrinkles or bubbles in the tape. Clean the slide with

methanol and air dry. Place a drop of the adhesive to be tested between the

two strips of tape. Using a single-edge razor blade, squeegee the adhesive

between the tape strips, maintaining a 30-deg angle between the slide surface

and the razor blade. The length of the applied strip shall be at least 2.5

inches. Carefully remove the tape and cure the adhesive according to 4.5.5.

After cure, the test specimens shall be allowed to cool to room temperature.

Resistance measurements shall be made using a Keithley 503 milliohm meter,

or equivalent, in conjunction with a four-point probe system. A special test

fixture must be made to facilitate accurate measurements. This fixture can

be made of an acrylic material with four spring-loaded contacts. The contacts

must be set into the acrylic so that the current contacts are two inches apart,

the voltage contacts are between the two current contacts, and the voltage

contacts are separated from each current contact by 0.5 inch. Place the

four-point probe fixture on the strip of conductive adhesive and ensure that

each of the probes is in intimate contact with the adhesive. Record the data

in ohms and determine the resistivity from the following formula:

p: R(wx t)

1

where P = resistivity in ohm-cm

R =.measured resistance, ohms

w = width in cm = 0.25 cm

t = thickness in cm - micrometer reading of adhesive plus

glass slide minus micrometer reading of glass slide

1 = length between inner pair of probes = 2.54 cm

This test shall be performed on a minimum of three specimens per test condition.

Test conditions shall include measurements at 25 C, at 60 C, at 150 C, and at

25 C after I000 hours at 150 C in a nitrogen ambient. The same specimens may

be used for each test.

105
O IGINAL PAG 

OF POOR QuAI.I"rY

4.5.8.2 Type II electrically insulative adhesives. Electrically

insulative adhesives shall be tested in accordance with ASTM D257 at

temperatures of 25 C and 125 C.

4.5.9 Thermal conductivity. Thermal conductivity shall be tested in

accordance with ASTM C177 or ASTM C518 or by use of instruments such as the

Dynatech C-Matic Thermal Conductance Tester or the Colora Thermoconductometer.

Measurements shall be made at 121 + 5 C.

4.5.10 Coefficient of linear thermal expansion. The coefficient of

linear thermal expansion shall be determined in accordance with ASTM D3386

over the temperature range of -65 + 150 C. The glass transition temperature,

coefficients, and temperature ranges corresponding to different slopes

of the curve shall be noted.

4.5.11 Electrical stability. The electrical stability of the electrically

conductive (Type I) adhesives shall be determined by applying a current density

of 139.5 amps/cm L (900 amps/inch2) to bonds made with the adhesives for a period

of I000 hours at 150 C in nitrogen. Specimens shall be prepared by bonding

0.0635-cm (25-mii) square gold-plated Kovar tabs to thick- or thin-film

conductor pads using the adhesive. The adhesive fillet shall be removed. A

minimum of five specimens shall be prepared per adhesive. The specimens shall

be series interconnected by wire bonding from the tab of one specimen to the

pad of the next. The resistance of each bond shall be determined initially

at 25 C prior to wire bonding by four-point probe measurement from the top of

the pad using a Keithley Model 191 Digital Multimeter or equivalent. The

resistance of the series of interconnected tabs shall also be determined at

25 C. The series of tabs shall be biased at a current of 0.562 + 0.016 amps

(139.5 + 3.9 amps/cm 2 or 900 + 25 amps/inch 2) at 5.0 + 0.3 volts-for I000 hours

at 150 _. The series resistan-ce shall be measured at-approximately 200-hour

intervals at 25 C out to I000 hours. After I000 hours, the resistance of

each bond shall again be measured at 25 C.

4.5.12 Dielectric constant, Type II adhesives. The dielectric constant

of the Type II adhesives shall be determined in accordance with ASTM DI50

at frequencies of 1 kHz and 1MHz at room temperature.

4.5.13 Dissipation factor, Type II adhesives. The dissipation factor

of the Type II adhesives shall be determined in accordance with ASTM DI50

at frequencies of 1 kHz and 1MHz at room temperature.

4.5.14 lonic impurities. A water-extract analysis shall be performed

to determine the total ion content (electrical resistivity), hydrogen ion

content (pH), chloride ion, sodium ion, and potassium ion contents. Federal

Test Method Std No. 406, Method 7071, shall be followed, except that the

specimens may be spread thin and cured directly in the Eylenmeyer flasks. The

total ion content in parts per million as sodium chloride shall be calculated

using the equation:

106
ORIGINAL PAGE f3

OF POOR QUALITY

23.47 (L 2 - LI)

W = parts per million as NaCl

where L2 = specific conductance of sample (micromho/cm)

L1 = specific conductance of blank (micromho/cm)

W = weight of sample (grams)

23.47 = grams NaCl/mho/cm

The factor "23.47" may be obtained experimentally or calculated as follows,

based on the use of 50 ml of water for sample extraction:

where

A

- 23.47 gms NaCI in 50 ml water/mho/cm

Ls

A = 1.4613 x 10-3 gram NaCl in 50 ml 0.0005 N NaCI

Ls = 6.225 x 10-5 mho/cm (specific conductance of 0.0005 N NaCl)

The pH shall be read directly using an Orion Model 801 pH Meter or equivalent

with a standard combination electrode by immersing the electrode in the water

extract and waiting for the instrument to stabilize. Chloride ion content

shall be determined by specific ion electrode (Orion or equivalent) or by

comparing the turbidity of a sample of the water extract to which silver

nitrate has been added in a Nessler tube to a series of chloride standards.

The sodium and potassium ion contents shall be measured using atomic absorption. All results shall be stated on the basis of a one-gram sample of adhesive.

4.5.15 Sequential test environment. Suitable test specimens shall be

exposed to the environmental conditions described below in the sequence given.

Test specimens shall be prepared using the adhesive in the application for

which it is proposed. An adequate number of test specimens shall be prepared

to provide a minimum of I0 samples of each application. If several devices

are of the same type but different sizes, only a representative sample (a

large die and small die) need to be tested. Semiconductor die with different

backing materials shall be treated as different devices. After exposure to

the complete sequence of environmental conditions, the test specimen(s)

shall be visually examined with the unaided eye and at 30X for any evidence

of mechanical degradation such as missing, loose or cracked capacitors, bond

fillet cracking, crazing or peeling, etc. Measurements shall be made of the

bond strength and bond resistance (for electrically conductive adhesives).

4.5.15.1 Type I and II test conditions

I. Stabilization bake (MIL-STD-883, Method 1008, test

condition C, 24 hours at 150 C).

107
ORIGINAL PAGE =_

OF POOR QUALITY

2. Temperature cycling (MIL-STD-883, Method I010, test

condition C, except 200 cycles).

3. Constant acceleration (MIL-STD-883, Method 2001, test

condition D, Yl orientation only).

4. High-temperature storage (240 hours at 125 C followed

by 72 hours at 150 C).

5. PREPARATION FOR DELIVERY

5.1 Preservation, packaging and packin 9. Unless otherwise specified

by the procuring activity, the preservation, packaging and packing shall be

in accordance with MIL-P-II6, Method III.

5.2 Markin 9. Each container shall be marked in accordance with

MIL-STD-129. Marking shall include, but not be limited to, the following

information:

a. Manufactuer's name and location

b. Material trade name

c. Net weight or volume

d. Lot number, batch number and date of manufacture

e. Storage limitations and shelf life expiration date

f. Number and revision letter of this specification

g. Number and revision letter of procurement specification

6. NOTES

6.1 Ordering data. Procurement documents should specify, but not be

limited to, the following information:

a. Title, number and revision letter of this specification

b. Title, number and revision letter of procurement specification

c. Size and number of containers required

d. Manufacturer's product designation

e. Request for test data

108
References

•

•

•

•

e

Salvadore V. Caruso, J. j. Licari, K. L. Perkins, and

H. A. Schramm, "Design Guidelines for Use of Adhesives and

Organic Coatings in Hybrid Microcircuits," NASA TMX-64908,

December 1974.

K. L. Perkins and J. J. Licari, "Investigation of Organic

Adhesives for Hybrid Microcircuits," NASA CR-15060, July 1975.

Dr. Jerry E. Sergent, "Electrical Properties of Epoxies and

Film Resistors," NASA CR-149980, March 1976.

J. H. Mason, Jr. "Electrically Conductive Epoxies--How

Reliable Are They?" 1980 ERADCOMMicrocircuit Symposium.

Tom P. L. Li, Charles C. Tang, and G. J. Barton, "Electrical

Stability of a Conductive Epoxy Bonded Interface," Proceedings

31st Electronic Components Conference, May 1981.

109

._, U.S. GOVERNMENT PRINTING OFFICE 1982--546-071/148 REGION NO.4

l/3

8

[-,

z

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