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IMBSIR 78-1590 (NASA)

Loose - Particle Detection in

Microelectronic Devices

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John S. Hilten

Paul S. Lederer

J. Franklin Mayo-Wells

Carol F. Vezzetti

Electrosystems Division

Center for Electronics and Electrical Engineering

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

October 1978

Final

Issued January 1979

3

Prepared for

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National Aeronautics and Space Administration

Goddard Space Flight Center

Greenbelt, Maryland

NBSIR 78-1590 (NASA)

> I < LOOSE - PARTICLE DETECTION IN

MICROELECTRONIC DEVICES

JUL in 197^ —

, » I '

1 1-

John E. Hilten, Paul S. Lederer, J. Franklin Mayo-Wells, and

Carol F. Vezzetti

Electrosystems Division

Center for Electronics and Electrical Engineering

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

October 1978

Final

Issued January 1979

Prepared for National Aeronautics and Space Administration

Goddard Space Flight Center

Greenbelt, Maryland

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

CONTENTS

LOOSE-PARTICLE DETECTION IN MICROELECTRONIC DEVICES

Page

Abstract I

1 . Introduction 1

1 . 1 Background 1

1.2

General Considerations 2 2. Experimental Work 3 2.1 PIND Trials 3 2.1.1 Apparatus 3 2.1.2 Procedures 5 2.1.3 Microelectronic Device Specimens 7 2.1.4 PIND Trials on Group II Specimens 9

2.1.5 PIND Trial on Group III Specimens 12

2.2 Characterization of Shock Accelerations Imparted by

Commercial Apparatus 12

2.2.1 Pre-Test Shock Apparatus C 12

2.2.2 Co-Shock Apparatus, System B 13

2.3 Other Tests 13

2.3.1 Preliminary Tests with Group I Specimens 13

2 . 3.2 Comparison of Detection Performance of Four

Ultrasonic Transducers 13

2 . 3.3 Pneumatic Co-Shock Experiment 13

3 . Results and Conclusions 1^

3.1 PIND Tests on Group II Specimens 14

3.2 PIND Trial on Group III Specimens 16

3.3 Characterization of Shock-Accelerations Imparted by

Commercial Apparatus I 6

3 . 3.1 Pre-Test Shock Apparatus C 16

3 . 3.2 Co-Shock Apparatus, System B I 8

3 .^ Preliminary Tests with Group I Specimens I 8

3.5 Comparison of Detection Performance of Four Ultrasonic

Transducers 21

3.6 Pneumatic Co-Shock Experiment 21

3.7 General Observations 22

3 . 7.1 Electrical Noise 22

3 . 7.2 Mechanical Resonance 22

3 . 7.3 Operator Variability and Fagigue 22

Recommendations 23

h.] Recommendations Relating to Test Method 2020 23

A. 2 Recommendations for Further Work 2k

5 . References 25

Tables 27

Figures ^1 Appendix I 52
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LOOSE-PARTICLE DETECTION IN MICROELECTRONIC DEVICES

John S. Hilten, Paul S. Lederer, J. Franklin Mayo-Wells,

and Carol F. Vezzetti

ABSTRACT

The work described constitues an evaluation of the test procedures and apparatus specified in MIL-STD-883, Test Method

2020, Particle Impact Noise Detection Test. The major experimental effort described - a comparison of procedures and apparatus - is based on the use of specially prepared specimen

device packages known either to have or not to have a particle

present. Other experimental efforts reported include characterization of the accelerations imparted to a specimen device by

pre- and co-shock apparatus, a brief study of the effectiveness

of couplant materials in transmitting mechanical energy to the

specimen device, and a comparison of the output signal level

from four different ultrasonic detection transducers under

otherwise identical test conditions. As part of the plan of

work, 252 of the specially prepared devices, representing six

package types, were characterized (as containing particles or

not) by several test procedures in order to provide a set of

specimens for use by the sponsor in a proposed i nterl aboratory

evaluation of FIND testing. Problems associated with this

effort are discussed. Results of the work are presented,

together with conclusions and recommendations for further work.

A result of interest is that the acceleration imparted by the

single sample of the pre-test shock apparatus tested is on the

order of 1.5 times the maximum specified by the Test Method.

Keywords: Acoustic emission; couplant; co-shock; detection;

electronic package; impact noise; microcircuit device; particle

detection; particle impact noise detection; FIND; pre-shock;

seeded specimens; transducer.

EXECUTIVE SUMMARY

Part i cl e- impact noise detection (FIND) is a widely used means of detecting

the presence of particles in packaged microelectronic devices for critical

applications. The basic FIND principle is that when a specimen device

package containing a free particle is shaken, the high-frequency acoustic

noise from the resulting impacts between the particle and the package

interior may be detected by a suitable transducer onto which the specimen

is mounted. A major difficulty with the FIND technique is that particles

may be immobilized, or "locked up," during testing and at a later time

become free, perhaps during operation of the device at a time when simultaneous contact between a free conductive particle (for example, from the

bonding process) and conductive elements may result in short-circuit failure

of the device.

The work described constitutes an evaluation of the test procedures and

apparatus specified in MIL-STD- 883 , Test Method 2020, Fartlcle Impact Noise

Detection Test. The major experimental effort described -- a comparison of

procedures and apparatus -- is based on the use of specially prepared specimen device packages known either to have or not to have a particle present.

I
The intent of the work was not to provide in any sense a definitive

study of FIND procedures, nor was it to devise an exceptionally ingenious

method that would solve "the" FIND problem. As an index to the state of

knowledge in the FIND area, consider the following: It has been estimated

that a thorough examination of one aspect of FIND -- the role of electrostatic mechanisms in the immobilization and release of particles — would

require over five man years to achieve basic understanding with no guarantee of any information being developed that could be used directly in

FIND testing (although it is likely that Information that could be used

by microelectronic device designers would be generated). As to the

existence of a single FIND problem, for each device technology there can

be many compositions, shapes, and sizes of foreign particles, and individual

device types will have differing microgeometries within a single productline grouping of similar devices.

It was therefore recognized at the outset that the NBS contribution would

have practical emphasis and concentrate on hands-on evaluation.

Accordingly a preliminary line of work was established to provide NBS

staff with operating experience in FIND testing according to Test Method 2020;

this work followed earlier work for SAMSO which was concerned with a preliminary evaluation of couplant performance [1,2].^

The exper iments carried out in this stage of the work are described in 2.3.1,

with results given in 3.^. This plan of divided description of tests and

results is followed throughout to provide as clear as possible a distinction

between the experiments themselves (section 2) and the information resulting

from these experiments (section 3)

A result of this early work was the development of a technique for comparing

the detection capability of various methods and configurations and settings

of apparatus. In this technique, the output of the ultrasonic detection

transducer is fed to the vertical amplifier of an oscilloscope for which the

horizontal deflection signal is the sweep sawtooth voltage corresponding to

the drive frequency of the shaker used to excite the specimen device. For

comparing the effects of different excitation frequencies, the acceleration

level is held constant and the shaker frequency is swept, so that the re- sulting oscilloscope trace is a plot of detection signal amplitude as a function of excitation frequency.

Other results from the first stage of work carried out on device packages

without dice or leads relate to a correlation between the test acceleration

level and particle lock-up. The most effective acceleration level appears

to be highly device-dependent, a finding that was substantiated in the main

body of tests on specially prepared devices.

These second-stage tests were carried out on 252 specimen devices, representing six package types and a number of different seed particle sizes in

several materials (see table 2 for detailed list); these devices were characterized by the commercial supplier as either intentionally seeded

with a single particle or free from any particle that could result in detection in a FIND run. (it should be noted that particles such as aluminum

1 Figures in brackets refer to literature references given in Section 5*
spheres 0.025 mm in diameter have a low enough mass -- nominally 0.02 iif -- that the supplier, in common with other test operators, did not regard

Test Method 2020 procedures as adequate for their detection, even if free.)

These seeded and unseeded specimens were the subject of seven trials in the

MBS laboratory and, later, of three additional trials in the supplier's

facility (Appendix 1 constitutes detailed information on the results from

each trial; summaries are presented in table 5 for NBS and table 7 for the

suppl ier)

After several of the NBS trials were completed, it became obvious that

according to the supplier's characterization (seeded or unseeded) the NBS

results were showing low detection scores for seeded specimens and, even

less understandably, detections in unseeded ones. There were a number of

possible explanations; these are examined in detail in 2.1. A. Although it was not possible to arrive at a definitive expianation of the anomalies,

it is likely that some event affected the specimens between the time they were tested prior to shipment to NBS by the supplier and the time of the

first NBS trial. It is noteworthy that the three post-NBS trials conducted

by the supplier (at his suggestion, in an attempt to resolve uncertainties)

are in better agreement with the NBS results than with his initial characterization. A more comprehensive discussion of these points is given in 3-1

A part of the work was to characterize the shock acceleration imparted by

a pre-test shock and a co-shock apparatus, both being commercially available

devices (co-shock refers to the application of shock acceleration while the

specimen is being driven by the shaker). The evaluation of the pre-test

shock apparatus was carried out in the light of the suggestion that some event

had occured to change the characterization of the specimen devices, as all

NBS trials involve applying pre-test shock for each specimen with the single

sample of apparatus purchased for the purpose. The results, discussed in

detail in 3-3.1, suggest that the apparatus is likely to provide peak acceleration on the order of 1.5 times the maximum specified by the Test Method.

Whether this excess is sufficient to free or produce new particles or to

immobilize free ones must remain conjectural. The supplier did report that

in at least one instance a broken lead was found when an unseeded specimen

was opened for inspection. (Only a few specimens were available for direct

examination, as a major purpose of the specimens was to serve as a wellcharacter i zed set of specimens for use by the sponsor in a proposed interlaboratory evaluation of FIND testing.)

Descriptions of other experiments and their results are considered to be

principally matters of detail and are therefore not specifically identified

in this summary.

The chief recommendation applying to the development of the Test Method,

given in 4.1, is that semi-automatic apparatus be used to avoid difficulties

with operator fatigue, judged to be severe in a production line testing

operation. It should be pointed out, however, that the NBS results, even when corrected as suggested in 3.1, do not show high detectability scores

even for the special particles used as seeds, which may not be (indeed

probably are not) typical of the free particles enclosed in sealed microelectronic devices on the production line. As device geometries grow

smaller, the size of an "acceptable" conducting particle will drop, yet there

is no guarantee that the mechanisms producing particles will compensate by

generating smaller particles, although if this were the case present-day

FIND procedures would not be likely to detect them. The point is simply that

I I I
the FIND art is an uncertain one; the relatively limited NBS trials (compared

to operators who have tested tens of thousands of devices) can perhaps best serve to provide a caution relating to overreliance on FIND as a method of

qualification. It is in this light that the following report should be read.
1. INTRODUCTION

1 .Background

The work contained in this report was sponsored by the National Aeronautics

and Space Administration under purchase order S39193~B.

For over a decade, various part I cl e- impact noise detection (FIND) methods

have been used in the electronics industry as a product assurance method of

detecting the presence of particles in packaged microelectronic devices [3].

The basic FIND principle is that when a specimen device package containing

a free particle is shaken, the high-frequency acoustic noise from the resulting

impacts between the particle and the package interior may be detected by a suitable transducer onto which the specimen is mounted. A major difficulty

with the FIND technique is that particles may be immobilized, or "locked up,"

during testing and at a later time become free, perhaps during operational

use of the device at a time when simultaneous contact between a free conductive particle (for example from the bonding process) and conductive elements

may result in short-circuit failure of the device.

MIL-STD -883 Test Method 2020, Fart id e- Impact Noise Detection Test, developed

under the aegis of the Defense Logistics Agency, is intended to encompass the

best FIND technology suitable for production line testing of devices. The

Test Method is therefore continuously subject to analysis and review for

improvement

The work described constitutes an evaluation of the test procedures and apparatus of Test Method 2020 and, more specifically, responds to the following

tasks

(

1 ) Evaluate existing FIND procedures, apparatus, and techniques using

specially prepared microelectronic packages known either to contain

or not to contain a seed particle.

( 2 ) Characterize the accelerations imparted to a specimen device by a selected commercially available FIND system incorporating means for

solenoid-generated co-shock and a low- impedance output to the

detection system.

( 3 ) Evaluate co-shock methods experimentally; on the basis of experience

from this evaluation, propose modifications or new techniques.

(A) On the basis of the experimental work, investigate other aspects of

FIND procedures that appear to be of interest, such as noise levels

in the detection signal, and the like.

(5) Frovide suitable seeded and unseeded specimen devices for the evaluation of task 1, including devices in the following configurations:

TO- 5 , TO-I 8 , TO- 3 , 16-lead ceramic dua 1 - in-1 ine, l4- or l6-lead

ceramic flatpack with metal lid, and 14- or l6-lead ceramic flatpack

with ceramic lid, with the following stipulations:

5.1 Each seeded package shall contain only one particle;

5.2 All devices shall be fabricated and inspected in a manner that

1
ensures there Is little chance of a non-seed particle remaining

in the package following closure;

5.3 Each package shall contain a die and all customary wire lead

connections for the device;

5.4 Seed particles primarily shall be in the form of gold, aluminum,

lead (or solder), and silicon-aluminum spheres and shall cover a particle-size range from 0.025 to 0.127 mm in diameter, with a higher proportion of seed particles in the smaller sizes.

(6) Using procedures specified in Test Method 2020, test the devices of

( 5 ) to determine for each device whether a particle Is or is not

present. Repeat the tests several times in order to provide experimentally characterized sets of devices suitable for use in a proposed

i nter 1 aboratory evaluation of FIND procedures.

1.2 General Considerations

Examination of the FIND testing literature [3] and contacts with various

workers indicate that the major difficulty with FIND methods is lock-up of the

particle to be detected. [4,5] Motion-picture films taken during FIND testing

of a device package with a window in the lid and with a number of free particles

present initially show impacts occurring with the interior of the package or the

die at intervals of a few milliseconds per particle as long as the particles

remain free. However, as the test time lengthens, more and more particles be- come immobilized. This observation illustrates one difficulty with FIND test

procedures -- testing a device may result in lock-up of an initially free particle

before detection occurs. If the particle were to remain immobilized, and were

not short-circuiting conductive elements, or straining a bond, this situation

would be acceptable. The problem is that as the details of even the most

prevelant trapping mechanisms are not known (either in general or for a given

device type), there is no guarantee that the particle will remain locked up,

and, in fact it may become free during operation of the device, with the

possibility of consequent device failure from short-circuit or other cause.

This discussion assumed that the particle to be detected was free initially;

however, experience shows that the problem of freeing an initially locked-up

particle (and of keeping it free long enough for detection) is severe. It may be thought that if the particle is not free, it should be left alone; the

question is of course, "How free is free?" Given the state of knowledge of

particle lock-up, the FIND test designer is forced to turn to the application

of shock acceleration to the specimen device and to select a level of shock

acceleration that will exceed the worst case to which the device is likely to

be subjected during its operational life. To implement this concept. Test

Method 2020 calls for a pre-test shock to be applied to all specimen devices

and for a co-shock to be applied while the specimen is being excited on a shaker^ armature if no detection signal is received initially.

In addition to pre-and co-shock acceleration levels, other parameters that

affect the ability of a given FIND procedure and apparatus to detect particles

To correspond with the usage of MIL-STD-883 , the sponsor has requested that

the more technically precise term "vibration exciter" be replaced by the term "shaker."

2
i nc 1 ude

(1) package type, device type, and materials of construction;

(2) mass (or size) and composition of particles to be detected;

(3) duration of test;

{h) number of tests run on a given specimen device;

(5) mechanical properties of material used to "couple" specimen to

ultransonic detection transducer;

(6) ultrasonic detection transducer sensitivity and frequency response;

(7) electrical noise characteristics of signal cables subject to flexing

or vibration;

(8) detection system gain, frequency response, and signal noise levels;

(9) shaker acceleration level and frequency;

(10) frequency of application of co-shock acceleration; and

(11) spectral content of pre- and co-shock acceleration.

The work described below has taken these parameters into consideration.

2. EXPERIMENTAL WORK

2.1 PIND Trials

As indicated in the task statements, the main thrust of experimental work con- sisted of conducting trails of various PIND apparatus and procedures using

specifically prepared specimen devices known to have either a single particle

(hereinafter referred to as seeded) or no particle present in the sealed device

package

2.1.1 Apparatus - In actual PIND trials one of three configurations of apparatus

was used, based on either one of the two commercial PIND equipments specified

in Test Method 2020. Figures 1, 2, and 3 show block diagrams of the three con- figurations and table 1 identifies the components of the commercial PIND equipments. Photographs of apparatus are shown in figures 4 and 5- The threshold

level detector was built in-house in accordance with the specifications and

circuit diagram given in Test Method 2020. Also constructed in accordance with

the Test Method was a "Sensitivity Test Unit," used to apply a mechanical signal

to the ultrasonic detection transducer.

For all PIND trials unless specifically noted otherwise, the specimen devices

were subjected to pre-test shock using the commercial apparatus (C) specified

by Test Method 2020. Apparatus C consists of a hammer arranged to pivot around

the end of its handle (lever) in a vertical plane. A rotatable cam engages the

under surface of the lever near. the pivot; rotation of the cam alternately raises

and drops the lever, which action permits the lower end of the cylindrical metal

hammer head to strike a metal anvil, integral with the apparatus frame. The

3
frame, or base, also supports the cam axle and the lever pivot. A specimen device to be pre-shocked is attached to the upper end of the hammer head with the same couplant to be used in the FIND test for that device, and the cam rotated

so that the hammer raises and falls once. Measurements on the shock acceleration imparted by this apparatus are reported in 3-3. 1-

Test configuration 3 requires some explanation. A technique for comparing

the detection capability of various methods and configurations and settings of

apparatus was devised, in which the conditioned output of the ultrasonic detection transducer is fed to the vertical amplifier of an oscilloscope for which

the horizontal deflection signal is the sweep sawtooth voltage corresponding

to the drive frequency of the shaker used to excite the specimen device. For

experiments comparing the effects of different excitation frequencies, the

acceleration level is held constant and the shaker frequency is swept, so that

the resulting oscilloscope trace is a plot of detection signal amplitude as

a function of excitation frequency. In practice, a further refinement was required as follows. With a specimen device (known from experience to have

a free particle that shows practically no tendency to lock up) in place on

the ultrasonic detection transducer and the shaker and other system components

energized, the vertical position of the trace and the polarity of the oscilloscope y axis preamplifier are set so that the trace appears as a series of

faint vertical lines rising from a heavy base line, which represents the zero

level for the detection signal. Deflection upwards thus corresponds to increasing detection signal amplitude. For photographing the trace it is desirable that all parts of the trace show approximately equal brightness, and

in particular that the signal traces appear clearly. This requirement is met

by feeding the detection signal into an amplifier with a switch-selectable

amplification factor of 10 or 100 and in turn feeding the output of that

amplifier into the z-axis input of the oscilloscope to modulate the trace

intensity (The second amplifier is required to provide the high-level input

required for the z axis). The intensity controls are then adjusted to re- sult in a trace of approximately constant brightness as shown, for example, in

figure 6. This adjustment is made with the shaker operating at a fixed

frequency. Slight adjustments to the intensity settings may be required at

the beginning of each specimen test, depending on the device type and the

pa rt ic 1 es present

A further refinement was required with the system A amplifier when particles

at the high end of the mass range were detected. The signals resulting from

impacts of the relatively more massive particles at times saturated the amplifier,

as evidenced by peak clipping in the output signal. To eliminate this overloading of the amplifier, a simple voltage divider was used for specimen devices

known to have particles with diameters of 0,102 mm or larger; the ratio of the

divider was adjusted to be 1:10 at 150 kHz; at both 100 and 200 kHz the ratio

was measured and found to be within 2% of the 1:10 value. It is recognized

that, although this solution is useful for this laboratory evaluation in which

the size of the particle to be detected is known beforehand, other approaches

are required for FIND tests of production devices.

The MBS shaker with its associated control and drive equipment used in this

work has a frequency range from 5 to 5000 Hz, an upper acceleration limit

of ±67 g^, and a double-amplitude limit of 12.7 rnm. This shaker can be programmed to sweep within the specified frequency range from any pre-set frequency to any other pre-set frequency, with acceleration, velocity, or displacement held constant. The sweep period is adjustable from 0.1 to 999 min;

up to 99 sweeps may be programmed.

4
The oscilloscope used in all three test configurations has a frequency

response greater than 500 kHz and an input voltage deflection sensitivity

of 20 mV per screen division, or better.

2.1.2 Procedures - The general procedure used for each trial of N specimen

devices was as follows:

(

1 )

( 2 )

(3)

Note

(M

(5)

Note

( 6 )

( 7 )

Using customary laboratory procedures, calibrate the oscilloscope

vertical deflection amplifier with the control set to 20 mV/ div; the

sweep rate to 2 ms/div; and the trigger selection switch to EXTERNAL

(trigger signal from shaker drive).

If the laboratory shaker is to be used, calibrate the shaker control

system and the accelerometer built into the shaker armature, in

accordance with customary laboratory procedures, by means of a precision servo accelerometer and associated amplifier and display.

If the system A shaker is to be used, calibrate its acceleration

level control by means of a previously calibrated accelerometer

and associated amplifier and display, in accordance with customary

laboratory procedures. Mount the accelerometer on the shaker

armature next to a TO-5 specimen device centered on the armature;

repeat the calibration with a TO-3 specimen.

The purpose of this step is to calibrate the acceleration level control when the shaker armature is loaded by specimen devices of two

different masses. For this purpose, the masses of TO-5, TO-18,

ceramic dual in-line, and flatpack packaged devices were taken to

be equivalent.

If the system B detector module is to be used, calibrate the threshold

level monitor by applying a 30-mV peak-to-peak sine-wave signal to

the monitor input; adjust the controls so that the indicator light is

Just triggered ON by this test signal. Set the frequency of the test

signal to be that at which the detector module gain is greatest, the

nominal value is 155 kHz.

If the threshold level detector is to be used with system A components,

attach the drive transducer of the Sensitivity Test Unit face-to-face

to the ultrasonic detection transducer with the couplant to be used

in the trial. Repeatedly apply a stimulus pulse to the detection

transducer by actuating the Sensitivity Test Unit and adjust the threshold level detector to trigger approximately k times for every five pulses.

The design of the Sensitivity Test Unit is such that not all stimulus pulses will have the same amplitude.

Assemble the apparatus in the desired test configuration.

If system A components are used, adjust the audio amplifier for maximum aud ible s ignal

If system B components are used, adjust the audio amplifier gain

controls so that Impacts from a specimen device with a 0 . 025-mm-d i amete

aluminum (least massive seed particle) can be detected clearly. Do

not readjust the monitor controls.

5
( 8 )

Note

Note

(9)

( 10 )

( 11 )

( 12 )

Note

(13)

(IM

(15)

( 16 )

Energize the system, including the shaker operating at a fixed

frequency. Monitor system performance for 5 min. If any detection

means show that a signal has been received corresponding to a particle impact, check the system for sources of electrical and

mechanical noise. Do not proceed until the requirement for a no- i nd i cat ion period is satisfied. Record the electrical noise

level as observed on the oscilloscope. De-energize the shaker.

External sources of mechanical noise may cause problems.

The signal cable from the ultrasonic detection transducer may generate electrical noise when flexed. Dress the cable with care. Apply restraints with caution, but make sure that the cable does

not see resonances at the test excitation frequency or over the

test frequency range.

Clean the mounting surfaces of the ultrasonic detection transducer

and the pre-shock apparatus C with an acetone-soaked swab.

Select a specimen device and clean its mounting surface with an acetone soaked swab.

Apply cut strips of couplant E tape to the mounting surfaces of the

pre-shock apparatus and the ultrasonic detection transducer.

Mount the specimen to the pre-shock apparatus hammer head. If the

specimen is a TO-3 device, apply a thin strip of couplant E tape over

the device and onto the hammer head on both sides of the device.

TO-3 devices have rounded mounting surfaces (tops) and couplant E tape at the mounting surface does not provide sufficient restraint

when pre- and co-shock accelerations are applied.

Actuate the apparatus to apply pre-shock.

Remove the specimen from the pre-shock apparatus and immediately

mount it on the ultrasonic detection transducer. If the specimen is a TO-3 device, apply a thin strip of couplant E tape over the device

and onto the transducer on both sides of the device. Inspect the

mounted specimen for leads that touch. Separate the leads so that

they will not strike each other when the device is vibrated. Inspect

the mounted specimen for the presence of foreign material; remove such material. Inspect the mounted specimen for the presence of

damaged leads. If it appears that one part of a lead might move with

respect to another when the device is vibrated, cut the broken part

off or reject the device.

Energize the shaker at the intended acceleration level and frequency

(for frequency sweep, at the intended initial frequency). Monitor all

detection means used as soon as any power is supplied to the shaker.

If no particle impacts are detected within from 5 to 1 0 s of shaker

turn-on, apply co-shock acceleration to the specimen by the means selected for the trial! Monitor with care all detection means used.

If a particle impact is detected by any one of the means used, record

the specimen as being seeded in the given trial.

6
(17) If no particle impacts are detected within from 3 to 5 s of the

first co-shock, apply a second co-shock to the specimen. Continue

to monitor with care all detection means used. If a particle impact

is detected by any one of the means used, record the specimen as being seeded in the given trial.

( 1 8) If no particle impacts are detected within from 3 to 5 s of the

second co-shock, apply a third co-shock to the specimen. Continue

to monitor with care all detection means used. If a particle impact

is detected by any one of the means used, record the specimen as being seeded in the given trial.

( 19 ) If no particle impacts are detected within from 3 to 5 s of the third

co-shock, record the specimen as being particle-free in the given trial.

( 20 ) Remove the specimen.

( 21 ) Repeat steps 10 through 20 for 17 specimens.

( 22 ) At least, as frequently as every I 8 specimens, clean the mounting sur- faces of the pre-shock apparatus and the ultrasonic detection transducer;

apply new couplant.

( 23 ) Repeat steps 10 through 20 eighteen times.

(2A) After 36 specimens, repeat step 8. Continue only if the requirement

for the 5~min no- i nd i cat ion period is satisfied.

( 25 ) Continue with steps 10 through 20 and, as appropriate, steps 21

through 2k until all N specimens are tested.

The data sheet used in connection with this procedure is shown in figure 7- As shown, the sheet includes space for indicating the magnitude of the detection

signal as observed on the oscilloscope screen or as heard from the loudspeaker.

(The notation is intended to convey the following: A signal is recorded as being very small (VS) , small (S) , medium (m)

,

or large (L) in amplitude or duration. The VS notation is used to indicate a signal which may represent a false detection instead of a particle; S indicates a signal about which there

is little question that the signal represents a particle; there is no question

about signals designated M and L.) The noise level is that recorded in step 8.

The laboratory ambient temperature is measured at the start of a trial. The

data sheet also provides a code for indicating when a detection signal was received in the test sequence.

2.1.3 Microeleotroni-c Device Specimens - Three groups of microelectronic

specimens were used in the work. Each group consisted of intentionally seeded

devices, with a small number of unseeded devices as controls.

Particles used to seed specimen devices were chosen to be representative of

particles likely to be found in devices as a result of production and processing steps and ranged in mass from 0.1 to 21.1 yg. Particles of smaller mass were considered to be only marginally detectable and, if in the form of

a lump instead of a sheet or needle, much less likely to cause short-circuit

failure. The majority of seed particles were spheres of gold, aluminum, lead,

i^r silicon-aluminum, ranging in diameter from 0.025 to 0.13 mm; a limited

number were gold or aluminum flakes approximately 0.3 x 0.05 mm in size; and 12

7
were short lengths of fine gold wire.

The 25 specimens in Group I were immediately available at the start of the

work and, although they are empty packages with neither dice nor leads, were

used until more representative specimens became available. [Two of the Group I specimens are unseeded.]

The 252 specimens in Group II were fabricated for the work by an outside

supplier using dice that had shown on electrical fault; in other respects

(except, of course, the inclusion of a seed particle) the completed Group M

specimens are not distinguishable from production devices. In particular,

the Group II specimens included all connecting leads. Primarily because of

long procurement lead times, the Group II specimens became available only in

the fifth month of work, substantially later than planned.

The 165 specimens in Group III are hybrid packages that were produced for

NASA Marshall Space Flight Center in connection with another program [6].

These specimens have ceramic substrates (6.^ mm in thickness and sized just

to fit in the package) and external leads. No internal leads or metallization

are present. Group III specimens became available in the last month of work.

Table 2 gives for Group I specimens: device type, number of specimens,

seed material and diameter (all Group I seeds are spherical), and calculated

mass. (The diameter is known to on the order of 10 pm (O.OOOA in.); the

uncertainty in calculated mass values ranges from +120%, -66% for nominal

0.025“mm lead to +16%, -14% for nominal 0.150-mm lead; other values are +36%,

- 27% for 0 . 076 -mm lead, +52%, for 0.051-mm gold, and +24%, -21% for 0.100- mm gold.) The two unseeded specimens are so identified. Similar information

for the Group II and Group III specimens is given in tables 3 and 4, respectively.

The Group || specimens were prepared both for the NBS work and for intended

later use as subjects of an interlaboratory evaluation of FIND methods. Be- cause of questions about the characterization of these specimens that are raised later it is of interest to note the supplier's description3 of the

fabrication procedures used:

"1 Headers and cans or lids were purchased.

"2 Headers and cans were cleaned by the Freon spray process used for our high reliability assembly. Freon spray was conducted in a clean

room and the cleaned devices were sealed in special contaminant-free

plastic bags.

"3 The particles were purchased or supplied by NBS.

"4 The particle was placed inside the can or cavity of the device and

then the particle was optically measured.

"5 The can and header were inspected at 50X magnification for extraneous matter before and after insertion of the particle.

"6 The device was then sealed."

^In a letter from the supplier to J. S. Hilten,

raised by the authors.

in response to questions

8
The supplier has further Indicated that 20 seeded devices of each type and

seed were prepared for every three supplied to the NBS as specimens. The

specimens were selected on the basis that in each of four consecutive FIND

trials, a selected specimen showed a positive indication of the presence of

a particle, vvith the exception of specimens seeded with particles 0.025 rnm (0.001 in) in diameter.^ For specimens with this size of seed, the situation

depends on the particle material, as follows: The FIND test method and

apparatus used by the supplier were not capable of detecting aluminum particles 0.025 mm in diameter. Gold particles of this size were detected in

all devices except the ceramic dual in-line packages. Lead particles 0.025 mm

in diameter were detected in the TO-18 packages and in one of the flat-pack

ceramic packages. The supplier noted that the lead particles that were not

detected were probably immobilized by electrostatic charge and referred to

numerous microscope observations of the behavior of a lead particle of this

size in devices with glass packages and in open packages (incidentally, the

supplier indicated that these locked up small lead particles require the

application of very high acceleration levels -- up to 9000 ““ fo become

free). Unseeded devices were also subjected to four consecutive FIND trials;

those supplied as specimens not only showed no detections in these trials

but also no evidence of loose material in radiographic examination.

The supplier described the conduct of his FIND trials as follows:

"1 Three pre-mount shocks of 400-600 G's.

"2 Immediately (1-2 seconds) mount device on transducer.

"3 Vibrate and observe for 2 seconds.

"4 Co shock 1/2 second at approximately 200 G's.

"5 Vibrate and observe for 3 seconds."

The method for applying pre-shock excitation was to tap the specimens on a table top; co-shock excitation was applied with a No. 10 copper rod, in

accordance with Method 2020.

2.1.4 FIND Trials on Group II Specimens - Following receipt of the Group II specimens from the supplier, major comparative trials of FIND methods and

apparatus could be carried out, and accordingly the seven trials summarized in

table 5 were run. Trial 1 was Intended to provide a baseline for comparison

with the results from subsequent trials. The results from this trial (table 5,

last two columns) were considered unsatisfactory in that (l) the overall

percentage of seeded specimens for which seeds were detected is much lower

than anticipated on the basis of reports in the literature and NBS experience

with Group I specimens and (2) the number of false detections in unseeded

specimens is unexpectedly large. Trial 2 was conducted in the same manner as Trial 1, except that the test frequency was determined for each package type

from data provided in Test Method 2020. To use the data, it is necessary to

know the "average internal package height." Since this dimension is not defined

in the Test Method, it was taken to be the distance from the top of the

4 The tabular data include particle diameter or sizes in both SI and U.S.

customary units. For simplicity, a conversion to inches will be given the

first time a new SI dimension appears and not repeated.

9
microcircuit chip to the inside surface of the package lid. The test frequencies used were ^3 Hz for TO-5 cans, kS Hz for TO-3 cans, 6l Hz for TO-I 8 cans,

81 Hz for ceramic dual in-line packages (CDIP), and 96 Hz for both metal- and

ceramic-lid flatpacks. The results of this trial were in general agreement with

those of trial 1

At this point it was necessary to decide if the trials should be continued without an understanding of the low detection score on the one hand and the high

false detection level on the other or if the trials should be interrupted and

the initial characterization by the supplier checked. With respect to specimen

character izat ion , four probable situations were recognized:

(

1 ) the specimens were correctly characterized by the supplier, some event

which resulted in new specimen states took place subsequent to that

characterization and prior to the first MBS trial, and the NBS trials

adequately characterized the new states;

( 2 ) the specimens were correctly characterized by the supplier, the first

NBS trial resulted in new specimen states as these states were being

characterized, there was no further change in states, and NBS trials

adequately character i zed the new states:

( 3 ) the specimens were correctly characterized by the supplier, no change

in specimen states took place, and the NBS trials inadequately characterized the states; and

(4) the specimens were not correctly characterized by the supplier and,

regardless of whether the Initial specimen states were changed, the

NBS trials adequately characterized the states as they were at the

time of trial.

Other series of events, including combinations of causes and changes induced by

the trials themselves, are philosophically possible, but were not thought adequate in terms of explaining the major discrepancy. Situation (4) did not seem

likely for several reasons. The supplier is a major manufacturer of microelectronic devices and has PIND-tested many thousands of devices; there was no reason to assume that his procedures or apparatus should be at fault. While it

is true that immediate consecutive FIND testing of a series of devices has in

a few cases shown a tendency to promote particle lock-up, there is no evidence

for such a large effect as the present data require. A series of labeling errors

is of course possible, but suggests an improbably high degree of carelessness in

light of the intended use of the specimens- Situation (3) also was judged not

likely in the light of [NBS] experience with the Group I specimens and especially

in the light of results of a "control" trial of these specimens interpolated into

Trial I when the results indicated possible problems. Seed particles in 21 out

of 23 seeded specimens were detected (the two not detected have never been detected in an NBS trial), one specimen which was supplied as unseeded but which has

generally shown a positive reaction was again characterized as containing a free

particle, and no particle was detected in the remaining unseeded specimen. Work

with the Group 1 specimens and other tasks had provided considerable experience

with false detection problems; a thorough re-check of the apparatus showed no evidence of any source of mechanical or electrical noise.

Situations (l) and (2) are similar in that it is not possible to distinguish

between them on the basis of the new specimen states. Plausible explanations for

10
both situations exist. Rough handling during shipping or delivery could

result in (1); no positive evidence is available on this point. Comparison

of the test procedures used by the supplier and by NBS shows that the pretest shock excitation provided the specimen at NBS was much greater than

that indicated by the supplier. The Test Method specifies that the pretest shock be 500 to 1500 g^-, it further specifies the use of commercial

apparatus C or equivalent. Later work, described in 3.3.1, shows that with

a 10-g mass in the specimen position, the single apparatus C tested generated

a shock acceleration of about 2300 This was the same apparatus used

to apply pre-test shock to all the Group II and Group III specimens before

they were characterized at NBS. While it is attractive to regard the high

pre-test shock as responsible for "permanently" immobilizing some particles

while "generating" others (or breaking leads), the caution should be given

that manual tapping of specimens on a table with no apparatus is not likely

to yield consistent results in terms of peak acceleration imparted; long-term

experience with applying accelerometers to a wide variety of measurement

situations suggests that the variation in shock could be very much greater

than that indicated by the supplier.

The selection of situation (l) or (2) as the likely true situation suggested

that the trials should be continued without interruption as there was no reason to expect any further changes in specimen states and no way to restore

existing states to initial ones. The suggestion was made that, following the

NBS trials, the specimens be returned to the supplier for re-characterization;

this was done, with results reported in 3.1. Further discussion of results

is left to that section.

Trial 3 was a companion to Trial 2 with an acceleration level of ±20 twice

that of Trial 2. These trials taken together were intended to compare results

at the two acceleration levels specified in the Test Method.

Trial 4 was an attempt to determine the effect on detection performance of a downward frequency sweep from 250 to ^0 Hz used instead of a single fixed

frequency; in other respects the conditions were the same as those of Trial 2.

The period of sweep was 2 min; co-shock excitation was applied every 10 Hz.

The innovation of using a frequency sweep was suggested to match test frequency with (1) the range of internal heights expected as a result of manu- facturing tolerances and (2) other internal package dimensions. The frequency

range used corresponds to internal heights (dimensions) from 0.13 to 4.6 mm

(0.005 to O.lSO in) at ±10 g^ and corresponds to the frequency capability

specified for the shaker in the Test Method. The suggestion was also made

that a frequency sweep might dislodge particles in configurations such as flakes, chips, and rods with largest dimensions on the order of a few tenths

of a millimeter. (The logarithm of the frequency is inversely proportional

to the logarithm of the dimension; for a dimension of 0.025 mm, the correspond inding frequency is between 500 and 600 Hz.)

Trials 1 through 4 were all conducted with test configuration 2, using system

B components. Trial 5 was carried out with test configuration 1, using system

A components with an acceleration level of ±10 g^^ and co-shock excitation

^See 3.3.1 for a discussion of the uncertainties of this measurement.

With only the accelerometer in place (mass 0.2 g) , the shock acceleration

was about 2700 g^.
applied manually with a copper rod 2.6 mm in diameter (AWG No. 1 O) , as specified

in the Test Method. The intent of this trial was to compare the performance

of System A with that of System B.

Trial 6 was a repeat of Trial 1, with the purpose of comparing the results obtained using the same apparatus and techniques, and by the same operator, but

separated by an interval of time, in this case, by 90 days.

Trial 7 was carried out as an effort to characterize the specimens in a manner

identical insofar as possible to that used by the supplier in carrying out the

original selection of specimens.

2.1.5 FIND Trial on Group III Specimens - Toward the end of the work, the 165

hybrid microelectronic devices constituting Group III became available and

were used as FIND test specimens at the request of the sponsor. A single trial

with test configuration 2 was carried out; the acceleration level used was ±10 g-p

,

and the exciting frequency was 60 Hz. Pre-test shock was applied to all Group III specimens by means of apparatus C. In addition, fifteen of the Group III specimens were FIND tested in a preliminary trial In connection with attempts to

verify detection system performance in connection with trials on the Group II specimens. Test configuration 2 was used with pre-test shock applied by means

of apparatus C.

2.2 Characterization of Shock Accelerations Imparted by Commercial Apparatus

2.2.1 Pre-Test Shook Apparatus C - fK commercial piezoelectric accelerometer

(with a mass of 0.2 g, considerably less than that of a representative TO-5

specimen, which has a mass of 1 g) was mounted in the test specimen position

on the top of the hammer head of Apparatus C, and the shock levels imparted

by the apparatus to the accelerometer measured in a series of tests as follows:

(1) The accelerometer was mounted in a centered postion using couplant F;^

the acceleration shock level was measured for five consecutive actuations of the apparatus to establish measurement repeatability. In five additional runs, the accelerometer was removed and remounted and

the shock level measured; the data from these tests are Intended to

provide a measure of the variation introduced by remounting.

(2) A similar set of tests was repeated for couplants D and E. Couplants

D and E are tapes with adhesives on both sides; fresh tape was used

for each remounting.'

(3) The accelerometer was mounted in a centered position using couplant F; the acceleration shock level was measured with only the accelerometer

in place (a repeat of one of the measurements made in the previous

series) and then with masses of 1, 2, 5, and 10 g loading the hammer

Couplant F is described by the manufacturer as a water-soluble paste

capable of transmitting ultrasonic vibrations.

^Couplant D is a semi-transparent material about 0.13 (0.005 in) thick;

couplant E is a white material about 0.36 mm (O.Ol^ in) thick.

12
head. These tests were carried out with three couplants for a total

of 15 runs.

(4) The shock level was measured at four sites, one in each quadrant of

the top of the hammer head, to simulate substantial off-center attachment of a specimen. A fifth measurement was made with the accelerometer

centered. These tests were also carried out with all three couplants

for a total of 15 runs.

The shock levels were measured from photographs of the oscilloscope

traces; these photographs also serve as waveshape records.

2.2.2 Co-Shock Apparatusj System B - The same accelerometer as described in

2.2.1 was mounted in the test specimen position on the face of the System B ultrasonic transducer (which is integral with the System B co-shock apparatus),

and the shock levels imparted by the apparatus to the accelerometer measured

in a series of tests as described in 2.2.1. (In 3 and k substitute "ultrasonic

transducer" for "hammer head." The means of measurement of shock levels and

of recording waveshape were the same as those of 2.2.1.)

2.3 Other Tests

2.3.1 Preliminary Tests with Group I Specimens - A number of developmental

tests were carried out using Group I specimens and the generation of amplitudefrequency plots as described in 2.1.1 as an evaluative method. These experiments are summarized in table 6 and are concerned with the effect of couplant

type, seed particle mass, and acceleration level on detection signal level.

Also investigated were the effects of acceleration level and frequency on the

tendency of the seed particles to lock up. In this investigation, the time

from application of co-shock until lock up was recorded, or the run terminated

after 20 s ( i f no lock up occurred).

The preliminary tests also provided information on the repeatability of the

amplitude-frequency technique and information on the effect of package type

on the frequency response of the detection signal for a given seed particle.

2.3.2 Comparison of Detection Performance of Four Ultrasonic Transducers - The

detection performance of four piezoelectric crystal ultrasonic transducers

manufactured by the supplier of System A components was compared in an experiment with FIND tests, using the amplitude-frequency plot method described in

2.1.1. Three of the transducers (H, I, and J) are the same model while the

fourth (G) is a variation on the basic model characterized by the manufacturer

as having "high sensitivity." The values of sensitivity in dB (referred to IV)

per 0.1 Pa as determined by the calibration chart supplied with each instrument are -76, -79, "78, and -79 for transducers G, H, I, and J, respectively. Test

configuration 3 was used, the acceleration level was ±10 and the 2-min

frequency sweep was from 25 to 250 Hz. Specimens were mounted with couplant D.

Amplitude-frequency plots were recorded for runs with each of the four transducers in turn, the specimen being a Group I package seeded with a gold ball

0.051 mm ( 0.002 in) in diameter. In a second test, plots were recorded for runs with transducers G and H, the specimen being a Group I TO-I 8 package

seeded with a lead ball 0.076 mm (0.003 in) in diameter.

2.3.3 Pneumatic Co-Shock Experiment - Consideration of mechanical means to

free immobilized particles led to the suggestion that co-shock acceleration be

13
applied along more than one direction. Further thought along these lines

resulted in a proposal to apply co-shock to the specimen with a pressure pulse.

As equipment, in the form of a quick-opening (1 ms) solenoid valve and an air

tank, was available to generate the required pneumatic pulse, a small-scale

experiment was carried out in which the system A ultrasonic transducer was mounted on the inside bottom of a small cylindrical aluminum pressure vessel

with removable lid, the vessel in turn being mounted on the NBS shaker armature.

Couplant E was used to attach the specimen to the transducer. With the lid in

place, three pneumatic co-shocks were applied with the shaker operating at

±10 at 60 Hz. Apart from the pressure vessel, the arrangement was that of

test configuration 1. A single run was carried out on 30 Group M specimens.

3. RESULTS AND CONCLUSIONS

3.1 FIND Tests on Group II Specimens

A summary of the detection scores in terms of the percentage of specimens

containing seed particles that were detected of the total number of seeded

specimens is included in table 5 for the seven NBS trials. As noted in the

narrative of 2.1.4, the results shown in table 5 for the first two trials led

to a review of the situation, which resulted in a decision to continue the

trials as planned. Examination of the results of trials 3 through 7 shows

general agreement with the earlier trials, and detection scores are disturbingly

low with false detection scores that are disturbingly high. Again referring

to 2.1.4, the analysis of the most likely true state of affairs and subsequent

contact and discussion with the suppliers of the Group II specimens resulted

in an offer by the supplier to re-examine the Group II specimens with the same FIND procedures used initially. The supplier actually conducted these trials,

identified as trials 8, 9, and 10 in table 7. The general agreement of the

detection results of these trials with the seven NBS trials strongly suggests

that, for whatever reason, the initial characterization is not valid. Table 8

shows the detection scores by seed particle for the ten trials; table 9 is a "corrected" table of detection scores assuming that a single positive detection

of a seed particle in a specimen in any of the trials renders that specimen as seeded. NBS overall, supplier overall, and combined overall detection scores

for each type of particle are also given in both tables. Note that table 9

does not cover detections in specimens that were initially characterized as unseeded and also that the calculated detection scores reflect only specimens

for which there was at least one positive detection in the ten trials. The

degree of agreement for the modified characterization is demonstrated in

Table 10, which shows the correlation between the seven NBS and the three

"post-NBS" trials conducted by the supplier, together with average values for

each size and composition of seed. Trials on specimens initially characterized

as unseeded are again not covered. To interpret the percentages given in the

table, consider the meaning of " 89 " given for an aluminum sphere 0.076 mm in

diameter in trial 3. This number indicates that in trial 3, 89 percent of the

tests carried out on specimens originally supposed to contain the seed in

question showed agreement with the modified characterization. The figures are

thus not detection scores as given elsewhere, but agreement scores.

Some general conclusions may be drawn from the results (these conclusions

and results refer only to the NBS trials unless otherwise stated), the chief

one being that detection of a seeded particle in a specimen package is to a large extent a function of the given package type. The overall uncorrected

14
detection scores by package type for the seven NBS trials are as follows:

TO- 18 80 percent

TO-5 67 percent

TO-3 55 percent

f 1 atpack wi th

metal lid 25 percent

f 1 atpack w i th ceram i c lid Ik percent

ceramic dual

i n- 1 i ne 21 percent

There may be significance to the fact that the overall detection score for the seven trials is 67 percent for specimens with metal packages and 23 percent for

specimens with ceramic or part-ceramic packages. Detailed data are given in

Append i x I

The largest detection-score difference between replicate trials is 5 percent.

However, there are only two sets of replicate trials, one set for system A

components in test configuration 1 (trials 5 and 7) and one set for system B components in test configuration 2 (trials 1 and 6). On this limited basis,

it is assumed that a difference on the order of 10 percent is probably significant, while smaller differences may have significance but require further trial.

A problem that should be noted in connection with multiple trials on a single

set of specimens is that it is possible for more and more particles to become

immobilized with each succeeding trial. For this consideration, " immobo 1 i zed"

is taken to mean permanently immobilized for the purposes of the FIND trials.

The results of all ten trials may suggest that a depletion of free particles

is occurring, but more trials would be required to establish a significant trend.

The above cautions for interpretation apply to the following results and con- clusions (all detection scores are uncorrected as given):

(1) The use of system B components in test configuration 2 provided

higher average detection scores (of approximately kS percent for

trials 1 and 6) than the use of system A components in test con- figuration 1 (score of approximately 39 percent for trials 5 and 7),

with all trials conducted at ±10 and 60 Hz.

(2) The use of the higher acceleration level of ±20 in trial 3 resulted in an improved overall detection score (55 percent as compared with 50 percent for ±10 g^, trial 2). There is evidence

that for certain package types, the higher level of acceleration

is desirable while the reverse is true for other package types. For

example, examination of the tabular results for trials 2 and 3 In Appendix I shows for the higher acceleration level an increase in

the detection scores for TO-3 and TO-5 specimens of 12 percent and a decrease in the scores for TO-18 specimens of 3 percent and in the scores

for ceram i c- 1 i dded flatppck specimens of 6 percent.

15
(3) The use of test frequencies based on the data provided in the

Test Method did not result in significantly higher detection

scores than the use of the single fixed frequency of 60 Hz.

The largest increase for seeded specimens was 6 percent for

flatpacks with ceramic lids (trials 1 and 2).

(4) The use of a frequency sweep from 250 to 40 Hz for each test

(trial 4) showed significantly lower detection scores compared

to those of trial 3; for all package types but one there was a drop ranging from 3 to l8 percent.

(5) In general, larger masses are more readily detected than smaller.

The ratio of the largest mass (10.6 yg for a gold sphere 0.10 mm

in diameter) to the smallest (0.023 ug for an aluminum sphere

0.025 mm in diameter) of any of the spherical seed particles used

in the Group II specimens is 460: 1 (the mass of neither the gold

nor the aluminum flakes is known). Examination of the data given

in the "totals" row in the tables of Appendix I shows that in only one instance -- in trial 2 -- was the actual number of positive

detections lower compared to the results obtained for a seed particle

of the same material but greater mass.

(6) Thirty-three percent (66 specimens) of the 198 seeded specimens

tested free of particles for all seven NBS trials. Fifty-six

percent (30 specimens) of the 54 "unseeded" specimens tested free

of particles for all seven NBS trials Eleven percent (6 specimens)

of the 54 "unseeded specimens showed positive detections for all seven NBS trials. The validity of the specimen characterization

on which these results are based has been discussed in the first

part of this section.

3.2 FIND Trial on Group III Specimens

The results of the trial described in 2.1,5 are summarized in table 11.

Note that the false detection rate (assuming that no free particles were

present in the unseeded specimens) is high. These limited results suggest

strong dependence on the package configuration, although the applicability

of this conclusion to actual devices is tempered by the fact that the Group

III specimens do not contain internal leads, and by the low detection scores.

It should be kept in mind, however, that a 0.17-yg gold sphere is only 0.025 mm in diameter.

The short trial of 15 seeded Group III specimens (one of each device represented by these specimens) resulted in three detections, all achieved before

co-shock was applied. Two of these were in 25 x 25 mm ceramic flatpacks,

and one in a TO-8 can with a gold wire seed. These results are not statistically significant, but are consistent with the trial summarized in Table 11.

3.3 Characterization of Shock Accelerations Imparted by Commercial Apparatus

3.3.1 Pre-Test Shook Apparatus C

- The selection of the accelerometer used

in the measurements of the acceleration imparted by the pre-test shock apparatus

is a compromise between the conflicting requirements of low mass, adequate

acceleration range, and high-frequency response. Accordingly, the measurements

described in 2.2.1 are subject to the following corrections and uncerta i n i es

16
(

1 ) The accelerometer used has a natural frequency of 5^ kHz, according

to its manufacturer. Experience with measurements using singledegree-of-f reedom accelerometers shows that accelerometer output

is flat to 20 percent of the instrument natural frequency; in this

case, to 10.8 kHz ("flat" is taken to mean that the accelerometer

output does not vary by more than 5 percent from the mean value over

the useful range). For frequencies above 10.8 kHz, it is necessary

to apply a correction factor. The waveshape of the shock acceleration imparted by apparatus C approximates a half-sine curve with a period of 50 ys (frequency of 20 kHz), as shown in figure 6. Assuming

a nominal damping ratio of 0.01 of critical damping (the transition

between underdamped and overdamped [7]), a correction of approximately

-16 percent is required to the measured peak acceleration value. This

correction is consonant with the manufacturer's estimate that the

frequency response is within ±7 percent of the 100-Hz value within

the range from 5 to 10,000 Hz.

(2) The manufacturer states that the sensitivity of the accelerometer

increases about one percent for every 250 over the range from 0

to AOOO g'n (for example, a reading of 4000 g'p requires a correction

of about "500 g'p) .

(3) The manufacturer estimates the calibration error to be within ±2.5

percent

(A) The manufacturer states that the shock- i nduced zero shift at nominal room temperature is less than ±6 percent of the reading over the

range from 1000 to 4000 g^. The initial peak reading is not affected

by this factor.

(5) Equipment required to check the accelerometer calibration at accelerations above ±60 g^ is not available. The accelerometer was calibrated

at ±20, ±A0, and ±60 g^ over a frequency range from 50 to 5000 Hz; the

results of this calibration were in agreement with the manufacturer's

data, taking into account the uncertainties discussed in this section.

(6) Replicate measurements of the acceleration levels imparted by apparatus

C result in deviations of no greater than 7 percent of the calculated

mean values.

(7) The overall uncertainty in the pre-shock measurements is estimated

to be ±12 percent, based on the above uncertainties together with

long-term experience with the accelerometer and associated instrumentation in question.

(8) The results given in this section have been corrected by approximately

-32 percent in accordance with (1) and (2).

The following results were recorded:

(1) The mean peak shock acceleration produced by apparatus C, loaded

with only the mass of the accelerometer and couplant tape, is

2700 <7n. The waveshape, shown in the upper photograph of figure 8,

approximates a half-sine curve; the duration of the first "pulse"

is approximately 50 ys.

17
( 2 ) Additional loading of apparatus C by a 19-g mass lowers the mean peak acceleration to approximately 2300 g^, 85 percent of the un- loaded value given in (l).

(3) The effects of remounting, of the use of any of the three couplants

tested, and of off-center mounting of the accelerometer makes no detectable difference in the mean acceleration values. Put another

way, deviations do not exceed 7 percent from the mean and are thus

well within the estimated uncertainty of the measurement.

3.3.2 Co^Shook Apparatus^ System B - The measurements described in 2.2.2 are subject to the same corrections and uncertainties given in 3.3.1, as the same accelerometer was used. The selection was again dictated by the need to

compromise between the conflicting requirements of low mass, adequate acceleration range, and high-frequency response. The correction factor is -13 percent

(-7 percent, frequency response; -6 percent, sensitivity) for the mean peak

acceleration levels measured; the overall estimated uncertainty is the same

as that g i ven in 3.3.1.

The following results were recorded:

(1) The mean peak acceleration produced by the co-shock apparatus,

system B, loaded with only the mass of the accelerometer and couplant

tape, is 1300 g^. The waveshape, shown in the lower photograph of

figure 8, exhibits a ringing frequency of approximately 14 kHz; decay

of signal amplitude to 10 percent of its initial peak value occurs

in approximately 1 ms.

(2) Additional loading of the co-shock apparatus, system B, by a 10-g mass lowers the mean peak acceleration to approximately 900 g^,

70 percent of the value given in (l).

(3) The effects of remounting and of the use of any of the three couplants

tested makes no detectable difference in the mean acceleration values.

Off-center mounting of the accelerometer reduces the mean peak acceleration to approximately 900 g^. Replicate measurements show results

with deviations from the mean value no greater than 5 percent of that

value, well within the estimated uncertainty of the measurement.

3.4 Preliminary Tests with Group I Specimens

A caution that should be kept in mind in connection with interpretation of the

results of these tests is the nature of the specimens, described in 2.1.3.

Empty packages may not be an adequate representation of complete devices.

The tests are described in 2.3.1 and table 6; results are as follows:

( 1 ) Couplant Tests

For the TO-5 and TO-I8 specimens, the use of tape couplant D resulted

in the largest output from the transducer-amplifier combination. With

couplant E the output was slightly less than that with D; with jelly

couplant F, the output was significantly lower than that with D, from

25 to 50 percent lower over the swept frequency range. For the metal

flatpack, these results were approximately reversed. Replicate runs with the three specimens repeated the ranking. If the output from

18
the amplifier is a function of the particle impact frequency and

of the composite frequency response of the coupl ant-transduceramplifier system, the results may be taken as indicating that the

frequency response of one or more of the couplants is not flat.

All three couplants are acceptable for FIND testing; for any one

set of test conditions, one couplant is likely to attenuate the

desired signals the least. Following these tests, tane counlant D was selected for use, as a number of FIND testing facilities are known to be using this type.

Test apparatus: configuration 3 with System A amplification and

detection system, NBS shaker, ultrasonic transducer H.

(2) Investigation of Effect of Farticle Mass

A preliminary analysis suggested that the output of the transduceramplifier system would be directly proportional to the mass of the

seed particle. The results of a series of amplitude-frequency tests

generally confirm this prediction, although the imprecision in the

knowledge of the seed particle mass (2.1.2) is large. Four TO-5

specimens seeded with particles as described in table 6 were used

for these tests. Nominal seed-particle mass, system output (values

given are for the approximate average output recorded at frequencies

between 25 and 75 Hz), ratios of masses (with the reference mass 1.3 ug)

,

and ratios of the corresponding outputs of the transducer-amplifier

system computed from the amplitude-frequency oscilloscope traces

shown in figure 6 (with the reference output 0.65 V) are as

fol lows

1 Farticle Mass

(ug)

System Output

(V)

Ratio of Masses Rat io of

1.3 0.65 1.0 1.0

2.6 1 ,0 2.0 1.5

10.6 ^.8 8.2 l.k

21 .

8.8 16.2 13.5

Test apparatus: configuration 3 with system A amplification and

detection system, NBS shaker, ultrasonic transducer H.

(3) Investigation of Effect of Shaker Acceleration Level

The amplitude-frequency tests were performed at three acceleration

levels on all Group I specimens with the following exceptions: the

four specimens seeded with 0. 025“rrim-d iameter particles (it proved

to be too difficult to keep these particles moving for the full

2 min required for the frequency sweep); two "seeded" specimens

that never showed the presence of free particles; and the two un- seeded specimens. Whenever particle lock-up occurred during a test,

the sweep drive was interrupted manually, the camera shutter closed,

the specimen co-shocked to free the particle, the shutter re-opened,

and the sweep continued.

Figure 6 shows typical oscilloscope traces obtained during these

tests. Data reduced from these and other traces indicate that the use of higher accleration levels results in (l) larger outputs from

19
the transducer-amplifier system with the same, or similar, seeded

specimens (about twice the output was observed when the same specimen was vibrated at an acceleration of ±20 gn as compared to ±5 g^) and

(2) wider frequency bands over which substantial output can be obtained from the transducer-amplifier system. For example, consider

the results from a specimen with a 0. 076-mm-d i ameter lead seed (the

specimen represented by figure 6, g, h, and i. In these photographs,

the output levels remain at their higher values until about 50 Hz

for an acceleration of ±5 gr\, to about 80 Hz for ±10 g-p, and to about

120 Hz for ±20 g^.

Test apparatus: configuration 3 with system A amplification and

detection system, MBS shaker, ultrasonic transducer H.

(4) Lock-up Behavior Tests

Investigation of the effects of acceleration level and frequency on the lock-up behavior of seeded specimens confirmed earlier observations that for TO-18 type specimens seeded with 0. 051 ~mm-d iameter

gold particles and 0,076-mm-diameter lead particles, lock-up occurs more readily at the lower frequencies of 20 and 30 Hz than at the

higher frequencies of 60 and 100 Hz, and at the higher acceleration

levels of ±20 and ±10 than at the lower acceleration levels of

±5 and ±3 g^- However, for similarly seeded TO-5 and metal flatpack

types, no relationship could be inferred between lock-up behavior

and acceleration level or frequency (no lock-ups occurred within the

20-s test period throughout all 1^0 tests). Data are given in table 12.

Test apparatus: configuration 3 with system A amplification and

detection system, NBS shaker, ultrasonic transducer H.

(5) Repeatab i 1 i ty

Plots of the transducer-amplification system output signal level for

amplitude-frequency tests on the same acceleration level conducted

at different times throughout the preliminary investigations showed

acceptable repeatability in the level over the test frequency range,

that is, no variation in level averaged over 10 Hz was larger than

about 10 percent. The three sample oscilloscope traces shown in

figure 9 demonstrate the typical degree of trace repeatability

observed

Test apparatus: configuration 3 with system A amplification and

detection system, NBS shaker, ultrasonic transducer H.

(6)

Investigation of Package Signatures in Oscilloscope Traces from

Amplitude-Frequency Tests

Comparison of the oscilloscope traces recorded during amplitudefrequency tests of the three Group I package types with nominally

Identical seed particles shows some characteristic differences in

the trace configurations and levels associated with each package

type (see figures 6 and 10). For example, with the same test

conditions, traces taken of tests on metal flatpacks show the widest

(and those for the T0-5s the narrowest) frequency band of enhanced

output. Again for the same test conditions, transducer-amplifier

20
system output is highest for TO-I 8 packages, followed by T0~5s and

then by metal flatpacks. These generalizations may tend to explain

ratios of detectability scores in some trials, but this type of

analysis should be approached with caution. It should be pointed

out that at least by visual inspection the similarities between

two trace patterns each associated with a different package type

may sometimes be greater than the similarities between two trace

patterns for the same type.

Test apparatus: configuration 3 with system A amplification and

detection system, NBS shaker, ultrasonic transducer H.

3-5 Comparison of Detection Performance of Four Ultrasonic Transducers

This experiment (2.3-2) was carried out primarily to see if use of the highsensitivity transducer type would result in an increased detection signal

amplitude (at least at some frequencies) and hence an improvement in signalto-noise ratio. It was anticipated that the results would likely be indicative at best, as the frequencies generated by the impact of various particles

in various package geometries are not well characterized (and almost certainly

vary over a wide range) and the transducer-output-as-a-funct lon-of-f requency

characteristics, as supplied by the manufacturer, show very uneven response,

with a local sensitivity maximum at 150 kHz. The difference in outputs for

the two types at this frequency is on the order of 2 dB; the major difference

between the two response curves is that the high-sensitivity instrument does

not show rapid drop either side of 150 kHz, but is relatively flat. For the

"normal" instrument, the response at 175 kHz is nearly kO dB down from the

150 -kHz value and then rises steeply again to about 10 dB down at 200 kHz.

The combined frequency-response characteristics of the transducers with the

amplifier are not available and were not determined.

Amplitude-frequency plots from the first test showed no significant variations

in the amplitude of the detection signal for any of the four transducers; all

signals were well above the noise level so that the presence of a particle was

indicated without ambiguity. In the second test, the output signal from the

high-sensitivity transducer G was found to have as much as 25% greater amplitude

than that from transducer H. The transducers are all said to be designed with

a maximum sensitivity at 150 kHz.

No real conclusions can be drawn from these results except that at some, but

not all, frequencies transducer G has greater sensitivity than transducer H. However, on a basis of the work overall, it seems likely that increased sen- sitivity would be useful in the detection of particles with a mass on the

order of a few tenths of a microgram or less (always provided that the particles

are free), as the detection signal from particles in this mass class may not

be much above noise.

It was considered that a thorough investigation of transducer sensitivity as

a function of frequency and of the frequencies generated by various particle

impacts was beyond the scope of the work.

3.6 Pneumatic Co-Shock Experiment

The results of this experiment (2.3.3) are ambiguous. With a trial of 30

Group II specimens initially characterized as containing detectable particles.

21
detection signals were received in 21 runs. This comparatively high detection

score is misleading, as it was found that the air pressure pulse impinging on

the ultrasonic detection transducer and connecting cable is capable of generating detection signals with no specimen present. It was judged that con- siderable work would be required to evaluate this technique adequately and,

with the assessment that it would require considerable development to implement as a production test, no further work was carried out.

3-7 General Observations

3.7.1 Electrical Noise - With any h igh- impedance output, electrical noise

produced in connecting cables is a serious concern. The designers of system B incorporate an amplifier in their test fixture specifically to gain the advantage of having a 1 ow- i mpedance connection from fixture to detection circuitry.

System A uses a "bare" transducer; consequently, the connecting cable carries

a h i gh- i mpedance signal, and electrical noise may be generated as a result of

cable motion or flexing. This problem is exacerbated at (1) lower frequencies,

for which the cable motion tends to be large, and (2) higher acceleration levels,

for which the inertial forces imposed on the cable tend to be large. A situation

in which a cable carries a h i gh- Impedance signal therefore requires the use ol^ low-noise cable and careful and constant attention to the manner in which the

cable is dressed.

3.7.2 Mechanical Resonance - The component used to couple the ultrasonic detection

transducer to the shaker also is intended to isolate the transducer from highfrequency mechanical noise, which may be present in the shaker itself or may

have other sources. If the combination of vibration frequency and amplitude

used results in a resonance in the coupling element, a spuriously enhanced

detection signal amplitude may result. This effect accounts for the enhanced

signal amplitude at approximately 200 Hz in parts c, f, i, and 1 of figure 6.

Note that there is little or no evidence of the resonance at lower acceleration

levels (parts a, b, d, e, g, h, j, and k of figure 6).

3.7.3 Operator Variability and Fatigue - The bare results of the FIND experiments and trials do not show the presence of an important factor to be considered

in the conduct of FIND trials (and, by inference, in production FIND testing),

that is, operator variability and fatigue. The NBS experience has been that

variability In operator performance (both between different operators and

between the same operator at different times) has the potential for affecting

results significantly; the results reported for the main FIND trials were

achieved with a single operator working within what were judged to be reasonable

limits of fatigue. In one test, the use of a second operator was attempted

until it became obvious that the results were significantly different from a test run under identical conditions and with the same specimens by the first

operator. Observation of the second operator (conducted in a manner so that

the second operator was unaware of the observation) showed that, according

to the first operator's criteria, a number of devices were being recorded as having no free particle present when in fact there had been an Indication of

detection. Operator fatigue was also reported to be a problem for a long

FIND trial. For example, one operator reported that in the course of a trial

extending over a number of hours he became aware that the effort required to

make correct decisions, especially for marginal detection signals with pulses

appearing fleetingly on the oscilloscope screen, was increasing rapidly and

that in order to continue he had to strive to heighten his state of mental

a 1 ertness

22
The NBS experience with operator fatigue can probably be extrapolated to

production testing in the form of a caution to managers of personnel conducting

routine FIND tests with manual determination of detection, per the Test Method.

The caution is simply that the work is demanding in one sense, yet the repetitive nature of It and the nature of the tasks themselves (e.g., looking at an oscilloscope trace) tend to reduce operator alertness and to induce "autopilot"

performance. A logical conclusion is that test operators should be chosen and

monitored with this warning in mind.

k. RECOMMENDATIONS

4.1 Recommendations Relating to Test Method 2020

These recommendations are based on a limited number of trials and in some cases on trials with packages that did not contain microelectronic device chips.

(1)

The most important positive recommendation is that detectability levels

be preset and the apparatus configured so that the decision as to whether

or not a specimen package contains a particle is made automatically.

Presumably, the detection criteria reflected in the apparatus settings

would be derived from trials on sample specimens of a given device

type or package type.

As noted in 3.7.3, NBS FIND experience supports the finding that

operator variability (both between different operators and between

the same operator at different times) is a significant factor con- tributing to inconsistent results in purely manual systems. This

observation is particularly pertinent when the test duration is long

enough to produce fatigue in the operator. The requirement for

adjustable levels of detectability reflects the finding that FIND

test results tend to be dependent on the package type for given test

conditions, that is, the detectability scores tend to Improve when

the test conditions match those found by trial to optimize results

for the given type. The apparatus should also automatically set

and control the acceleration levels applied to the specimen.

Note: Whether more than one acceleration level should be used in a production FIND test will depend on a tradeoff between the improvement

in detection performance resulting from multilevel testing, the

cost of testing, and the degree of reliability required by the

ultimate application.

(2) The NBS measurements show that the acceleration levels imparted to

a specimen by the specified pre-test shock apparatus are considerably

greater than the 1500 gp^ specified in the Test Method (the copy of the

Method available to NBS uses the figures "500 to 1500" in 2 (1) and

"500 to l800" g^ in 3.3.1. Since 3.3.1 refers to "2.1", it Is assumed

that 1500 g^ is the intended upper limit). This situation should be

Investigated and resolved, as the possibility exists that if FIND

test specimens are being subjected to higher shock levels than intended, some otherwise free particles are being either temporarily or permanently immobilized, and damage may occur to device components such

as leads.

(3) Before production testing is carried out on a given package type, a quas i -opt imized set of test conditions for that type should be determined

23
by parametric trials on wel 1 -character i zed specimens. A recom- mended means for conducting trials is the amplitude-frequency

plot method (in which the output of the ultrasonic detection transducer is fed into the vertical amplifier of an oscilloscope for

which the horizontal deflection signal is exciter sweep frequency)

d i scussed in 2.1.1.

(^) Consideration should be given to limiting initial acceleration

levels to ±10 g'p ^ or less, at least for some package types. The

acceleration imparted to the specimen package by the shaker is one

of the test parameters that should be investigated for each new package type. There is evidence in the NBS FIND data that for some package types lowered acceleration levels improve detectability as long as the levels do not fall below some package-dependent threshold,

and that for other types detectability is improved, for example,

at ±20 compared to that determined at ±10 When the data for

a given package type are either ambiguous or not available, consideration should be given to revising the Method to specity that the test

on each device be conducted consecutively first at ±10 g^, or less,

and then at ±20 g^ (see Note under 1).

(5) The Method should specify the maximum permitted impedance of the output from the detection transducer assembly, as cable noise is otherwise a likely problem. The specified impedance should be low compared

to the impedance of the transducer crystal Itself; a recommended means

of achieving this goal is to incorporate suitable impedance-matching

circuitry in the transducer assembly.

k .2 Recommendations for Further Work

(1) More trials should be conducted on wel 1 -character i zed specimen packages

to provide a data base for meaningful statistical analysis, particularly with respect to comparing the results of sets of trials in which

there is some change from one set to another in test conditions, apparatus, or technique. This recommendation is especially important in

the light of the facts that at this writing there are some questions

about the characterization of the 252 Group II devices® and that

neither the Group I packages nor the Group III hybrids without internal leads are entirely representative of production microelectronic

devices

(2) An area that does not seem to be addressed in FIND literature is optimization of the ultrasonic detection transducer and associated

circuitry. Fresent forms of FIND apparatus are designed to operate

at a center frequency of 150 kHz. A simplified analysis of particleimpact trajectories and times suggests that higher frequencies may

be generated; it is therefore recommended that spectrum analyses

of the frequencies present in the signal of a wide-band detection

transducer (for example, with a useful frequency response at 1 MHz)

be conducted for a representative combination of test conditions and

specimen packages.

It Is recommended that in future work, when successive trials on a given

group of devices yield anomalous results, the devices be opened for direct inspection.

Ik
(3) The NBS work on couplants made use of existing available FIND

apparatus, with limited frequency response. It is recommended

that further work on couplants be carried out in conjunction with (2)

with wide-band, flat-response transducers as both driver and detector, the specimen couplant being sandwiched between the two

t ransducers

(4) As new apparatus becomes available for FIND testing, it should be

evaluated with respect to the requirements of the Method and with

respect to the performance of the best apparatus hitherto available.

It is specifically recommended that NBS investigate the performance

of at least one commercial apparatus that is now available and that

does not rely on operator Judgment for determination of particle

detect ion

(5) There is considerable evidence that lock-up problems with small

particles of relatively low mass are at least in part the result

of electrostatic effects, particularly when the package material

is piezoelectric, as may be the case with some ceramic flatpacks.

It is recommended that an investigation be carried out on the

magnitude and polarity of charge likely to be present during FIND

testing of ceramic packages and on means available for neutralizing

the charge.

(6) Another area that needs to be studied is the effect of the detailed

internal configuration of a device on the statistical probability

of particle lock-up, for particles of sizes, materials, and, if

possible, configurations most likely to be produced as the device

moves through its processing steps. Analyses should be carried

out of at least the most likely particle-device interior interactions, including an investigation of the frequencies generated,

average impact repetition rates, and the like. An example of this

work might be a consideration of the effect of lead-substrate angle

on the provision of (wedge-shaped) trapping sites.

It is even possible that FIND considerations should affect microelectronic device design.

5. REFERENCES

[1] Bull is, W, Murray, Ed, Semioonduotov Measurement Technology: Frogress

Report January 1 to June 30, 1976, NBS Special Fublication 400-29,

pp. 75-76 (April 1977).

[2] Bull is, W. Murray, and Mayo-Wells, J, Franklin, Eds, Semiconductor Measurement Technology: Frogress Report July 1 to September 30, 1976,

NBS Special Fublication 400-36, pp. 52-53 (July 1978).

[3] Adolphsen, John , W. A. Kaldis, S A. R. Timmins, A Survey of Farticle

Contamination in Electronic Devices, Goddard Space Flight Center,

Greenbelt, Maryland, X-31 1 “76-266

[4] Anon., Loose Farticle Detection Investigation Report, internal McDonnell

Douglas report prepared by Components, Materials and Frocesses Branch

for the Delta Frogram and transmitted by memorandum A3-238-AEEE0-M-76-95

(25 Aug. 76) from J. L. Holmgren to D. W. Tutwiler.

25
[ 5 ] Keister, F. Z., The Use of Particle Impact Noise Detection for Contamination Control in Hybrid Microelectronic Modules, Hughes Aircraft

Company Report No. P77“196, HAC Ref. No. D1927 (prepared for NASA

George C. Marshall Space Flight Center, under contract NAS 8

- 30876 )

[6] Keister, F. Z., Preparation of Calibrated Test Packages for Particle Im- pact Noise Detection, HAC Ref. No. D1927 (prepared for NASA George C. Marshall Space Flight Center, under contract NAS 8

- 30876 )

[ 7 ] Tong, K. N., "Systems with a Single Degree of Freedom," Chapter 1 of

Theory of Mechanical Vibration (New York: John Wiley £ Sons, Inc.,

i960)

26

USCOMM-NBS-DC
TABLE 1

COMPONENTS IN COMMERCIAL FIND SYSTEMS

Material in quotation marks is taken from respective manufacturers'

literature; measurements on the accelerations imparted are reported

in 3.3.

SYSTEM A

shaker and shaker control system

ultrasonic detection transducer

detector modules

CO- shock tool

operating range 1-15 g over lA-60 Hz;

designed to provide "extremely low mechanical noise background" above 100 kHz

sensitivity at 150 kHz of at least -77*5

± 2 dB (referred to 1 V) per microbar,

as specified in Test Method 2020, in SI units per 0.1 Pa (Note 1)

include filter, 60-dB amplifier; amplified signal available for input to os- cilloscope; signal to loudspeaker is

heterodyned with signal from tunable os- cillator to provide "characteristic

sound" for free particle

15"cm length of No. 10 copper wire

SYSTEM B energized d-c solenoid contacts transducer on combination co-shock fixture and flexible table to provide co-shock;

ultrasonic detection transducer sensitivity at 150 kHz of at least -77-5

with amplifier ± 2 dB (referred to 1 V) per microbar,

as specified in Test Method 2020, in SI units, per 0.1 Pa (note 2); 30-dB amplifier incorporated into fixture

co-shock push-button switch

detector module with co-shock control provides three means of monitoring test

- amplified detection signal available

for input to oscilloscope; high-frequency,

high-fidelity speaker for "presenting

noise bursts" when particle impacts occur; threshold level monitor with indicating light (once light is lit it stays

on until the monitor is reset manually)

Note 1 - The value of sensitivity as determined by the calibration chart supplied

with this transducer (H) is -79 dB (referred to IV) per 0.1 Pa (per m 1 crobar)

Note 2 - The value of sensitivity as determined by the calibration chart supplied

with this transducer (K) is -8l dB (referred to IV) per 0.1 Pa.

27
TABLE 2

GROUP I SPECIMENS

NUMBER

OF

SPECIMENS

PACKAGE

TYPE

PARTICLE CHARACTERIZATIO i

MATERIAL SHAPE

NOMl

DIAME

(mm)

NAL

ITER

(in)

CALCULATED

NOMINAL

MASS

(yq)

2 TO-5 Gold Sphere 0.102 0.004 10.6

2 TO-5 Gold Sphere 0.051 0.002 1.3

2 TO-5 Lead Sphere 0.152 0.006 21.1

2 TO-5 Lead Sphere 0.076 0.003 2.6

2 TO-5 Lead Sphere 0.025 0.001 .1

1 TO-5 Unseeded

2 TO-18 Gold Sphere 0.102 0.004 10.6

2 TO-18 Gold Sphere 0.051 0.002 1.3

2 TO-18 Lead Sphere 0.152 0.006 21.1

2 TO-18 Lead Sphere 0.076 0.003 2.6

2 TO-18 Lead Sphere 0.025 0.001 .1

1 TO-18 Unseeded

1 ^Flatpack Gold Sphere 0.051 0.002 1.3

1 Flatpack Gold Sphere 0.102 0.004 10.6

1 Flatpack Lead Sphere 0.076 0.003 2.6

^ with metal lid, 6.4 x 3.3 mm (0.25 x 0.13 in), 14 lead

28
TABLE 3

GROUP II SPECIMENS

NUMBER PACKAGE PARTICLE CHARACTERIZATION

OF

SPECIMENS

TYPE

MATERIAL SHAPE NOM

DIAM

(mm)

INAL

ETER

(in)

CALCULATED

NOMINAL

MASS

(pq)

3 TO-3 Gold Sphere 0.102 0.004 10.6

3 TO-5 Gold Sphere 0.102 0.004 10.6

3 TO-10 Gold Sphere 0.102 0.004 10.6 I 3 apPML Gold Sphere 0.102 0.004 10.6

3 ^FPCL Gold Sphere 0.102 0.004 10.6

3 ^CDIP Gold Sphere 0.102 0.004 10.6 1 3 TO-3 Gold Sphere 0.051 0.002 —.

1 1.3

3 TO-5 Gold Sphere 0.051 0.002 1 .3

3 TO-18 Gold Sphere 0.051 0.002 1.3

3 FPML Gold Sphere 0.051 0.002 1.3

3 FPCL Gold Sphere 0.051 0.002 1.3

3 CDIP Gold Sphere 0.051 0.002 1.3

3 TO-3 Gold Sphere 0.025 0.001 0.17

3 TO-5 Gold Sphere 0.025 0.001 0.17

3 TO-18 Gold Sphere 0.025 0.001 0.17

3 FPML Gold Sphere 0.025 0.001 0.17

3 FPCL Gold Sphere 0.025 0.001 0.17

3 CDIP Gold Sphere 0.025 0.001 0.17

3 TO-3 Gold Flake 0.051

xO.254

0.002

xO.OlO

3 TO-5 Gold Flake 0.051 0.002

1 xO.OlO xO.OlO

3 TO-18 Gold i Flake 0.051 0.002

xO.254 xO.OlO —

3 FPML Gold Flake 0.051 0.002

xO.254 xO.OlO —

3 FPLL Gold Flake 0.051 0.002

xO.254 xO.0.0 —

3 CDIP Gold Flake 0.051 0.002

xO.254 xO.OlO —

^flatpack witn metal lid, 16 lead

^flatpack with ceram. lid, 14 lead

^ceramic dual in-line package, 16 lead

29
TABLE 3 continued

GROUP II SPECIMENS

NUMBER

OF

SPECIMENS

PACKAGE

TYPE

PARTICLE CHARACTERI7ATI0N

MATERIAL SHAPE NO

DIA

(mm)

MINAL

METER

(in)

CALCULATED

NOMINAL

MASS

(ijg)

3 TO-3 Aluminum Sphere 0.127 0.005 2.9

3 TO-5 A1 uminum Sphere 0.127 0.005 2.9

3 TO-18 Aluminum Sphere 0.127 0.005 2.9

3 FPML A1 umi num Sphere 0.127 0.005 2.9

3 FPCL A1 uminum Sphere 0.127 0.005 2.9

3 CDIP Aluminum Sphere 0.127 0.005 2.9

3 TO-3 Aluminum Sphere 0.076 0.003 0.63

3 TO-5 A1 umi num Sphere 0.076 0.003 0.63

3 TO-18 Aluminum Sphere 0.076 0.003 0.63

3 FPML Aluminum Sphere 0.076 0.003 0.63

3 FPCL A1 uminum Sphere 0.076 0.003 0.63

3 CDIP Aluminum Sphere 0.076 0.003 0.63

3 TO-3 Aluminum Sphere 0.025 0.001 0.023

3 TO-5 Aluminum Sphere 0.025 0.001 0.023

3 TO-18 A1 uminum Sphere 0.025 0.001 0.023

3 FPML Aluminum Sphere 0.025 0.001 0.023 -

3 FPCL Aluminum Sphere 0.025 0.001 0.023

3 CDIP Aluminum Sphere 0.025 0.001 0.023

3 TO-3 A1 uminum Flake 0.051

xO.254

0.002

xO.OlO

3 TO-5 Aluminum Flake 0.051

xO.254

0.002

xO.OlO

3 TO-18 A1 umi num Flake 0.051

xO.254

0.002

xO.OlO

3 FPML Aluminum Flake 0.051

xO.254

0.002

xO.OlO

3 FPLL A1 umi num Flake 0.051

xO.254

0.002

xO.OlO

3 CDIP Aluminum Flake 0.051

xO.254

0.002

xO.OlO

30
TABLE 3 continued

GROUP II SPECIMENS

NUMBER

OF

SPECIMENS

PACKAGE

TYPE

PARTICLE CHARACTERIZATION

MATERIAL SHAPE

Nor DIAf

(mm)

^INAL

^ETER

(in)

CALCULATED

NOMINAL

MASS

(uq)

3 TO-3 Lead Sphere 0.076 0.003 2.6

3 TO-5 Lead Sphere 0.076 0.003 2.6

3 TO-18 Lead Sphere 0.076 0.003 2.6

3 FPML Lead Sphere 0.076 0.003 2.6

3 FPLL Lead Sphere 0.076 0.003 2.6

3 CDIP Lead Sphere 0.076 0.001 2.6

3 TO-3 Lead Sphere 0.025 0.001 0.098

3 TO-5 Lead Sphere 0.025 0.001 0.098

3 TO-18 Lead Sphere 0.025 0.001 0.098

3 FPML Lead Sphere 0.025 0.001 0.098

3 FPLL Lead Sphere 0.025 0.001 0.098

3 CDIP Lead Sphere 0.025 0.001 0.098

3 TO-3 Sil icon-ATuninum Sphere 0.127 0.005 2.7

3 TO-5 Silicon -Aluminum Sphere 0.127 0.005 2.7

3 TO-18 Silicon-Aluminum Sphere 0.127 0.005 2.7

3 FPML Sil icon-Aluminum Sphere 0.127 0.005 2.7

3 FPLL Silicon-Aluminum Sphere 0.127 0.005 2.7

3 CDIP Silicon-Aluminum Sphere 0.127 0.005 2.7

9 TO-3 Unseeded

9 TO-5 Unseeded

9 TO-10 Unseeded

9 FPML Unseeded

9 FPLL Unseeded

9 CDIP Unseeded

31
TABLE 4

GROUP III SPECIMENS

NUMBER

OF

SPECIMENS

PACKAGE

TYPE

PARTICL : CHARACTERIZATION

MATERIAL SHAPE NOMir

DIAME

(mm

)

^AL

FER

(in)

CALCULATED

NOMINAL

MASS

(VQ)

25 ^ 1 1/4x1 1/4 MB Gold Sphere 0.0457 0.0018 1.0

25 b

1 X 1 MB Gold Sphere 0.0356 0.0014 0.5

25 1 X 1 CFP Gold Sphere 0.0356 0.0014 0.5

25 ^ 5/8 X 5/8 MB Gold Sphere 0.0254 0.001 0.17

25 TO-8 Gold Sphere 0.0254 0.001 0.17

4 11/4x1 1/4 MB Gold Sphere 0.457 0.0018 1.0

4 11/4x1 1/4 MB Unseeded

4 1 X 1 MB Gold Sphere 0.0356 0.0014 0.5

4 1 X 1 MB Gold Wire 0.5

4 1 X 1 CFP Gold Sphere 0.0356 0.0014 0.5

4 1 X 1 CFP Unseeded

4 5/8 X 5/8 MB Gold Sphere 0.0254 0.001 0.17

4 5/8 X 5/8 MB Gold Wire 0.17

4 TO-8 Gold Wire 0.17

4 TO-8 Unseeded

^32 X 32 mm (1.25 x 1.25 in) metal butterfly package

^25 X 25 mm (1 X 1 in) metal butterfly package

^25 X 25 mm ceramic flatpack

^16 X 16 mm (0.63 x 0.63 in) metal butterfly package

32
SUMMARY

OF

SEVEN

FIND

TRIALS

CONDUCTED

BY

NBS

ON

GROUP

II

SPECIMENS

C l- O O T3 — 4_ (U

C

"O OJ

O (U <U E

0) 1_ LA <u

—

4-> 0 U1

O ' -a- -3- vO CN

0) o c 4) CSl CSI CN CN

Ci CO ZD Q. CO

i/i c 1- c 0 0 -o <u •— 4- (U E 4-1 -Q CO -o CO

O LA LA

O (U cn <u o <3^ -3- LA LA -3-

0) k- r- <u <U ^ 4-) o CO Q.

(1)

u CO o lO co

4-1 nj

CJ

4) > c — 0) o O o O

(U _J ^- 1— CN f— o + 1 + 1 + 1 + 1 o< o O

>- vO \0 Q. E O 4-1 1 o ^ CTk CA 43 O -3-

</) 0)

CN 1 1 43 k- 1 (U k- 0) Z o OA CA 5 o H Li- vO -3‘ -3- in LA

cr CN

Co•— E

4-1 0) oa

m CQ CQ o •M

(U E E E E

4-1 4) 43 43 43 0) CO 4-J 4-1 4-1 4-> o l/l in in in >- >- > CO CO CO lO

NX o CO CO CQ CQ *0 O o 43 —

sz E E E E —

CO 4) 43 43 43 1 4-> 4-1 4-> 4-1 Q. k- o 1/) m in in O. 43 o >» >« 43 >

CO CO CO CO 43

4-< o o o O

(/) (U (/) in

m in h- o 3 3 3 3 1 o 4-» 4-J 4-1 4-1 (U 43 43 43 43

1_ CO k_ k- k_ k- a. 43 43 43 43 Q. O. CL Q.

Q. Q. CL

a < < < <

-o

(U

(/) =)

(U CO CO CO CO

CQ OQ CQ OQ

to Z z z z

s:

CO

(D

O

— z '

CSI rA -3-

kXo X • •— in m X 43 CN LA •— 2 h- CN 43 •— c 03

k- •—

X 4J m X

>• c X o 03 X c E

43 •— 2 3 O

CT 03 43 crv CA OO 43 CL U

CA -3- CA Lm

C

14- 43 1 >4- T3

4-J o k- CL o

43 kO 2 43 O m X 4) E

u- 3 C O C —

43 43 "O m X 43

OO

O 43 4-J

C 1

1

o •— + + 1 + 1 H- E

43 0 k- X 43

4-> 4J

X c 43 c 43 "O

4-J in

4-> o 43 CL 3 2

03 O' o o o O 03 vO vD vD X 43 CL

43

X >-

4-J

X

C in 03 3 43 Ok U E • 43 < OQ < — T3 -X X 4-> 4) o E E E u X 43

43 43 43 43 o in CL

4-1 4-J 4-1 43 o 03 in in m X

C

>» >- >• 03 03 CO CO CO c in in >

•— 43 c

k_ 43 O) 3 -o E

-o 43 •— 43 C U

T3 •— 43 k- -o T3 43 14- Q- 0

'N 0 'N

O •— 43 in 4-

u CQ 5 k-

•o

CL 4- 43 •— k_ E .— k_ Q. m o Ok

43 43 4) 43 43 43

—

C 3 Q. 4-1 3 Cl k- 43 C Q. in C D. in — 43 k_ 43 O >- 43 O 43 4J X X O CO X O 2 c E m

43 3 •—

in

O

C

X -X k_ X

c_> o O 43 43 O Q. X c

in

m Q.

X

X • — 3 3 43 m c X 4-1 4-1 4-> 1 •— *o X

43 43

O c • —

U k- 03 03 o - 43 2

43 43 3 — 43 CL Q. C -Q 43 k- o -O

CL Q. 43 43 43

O 43 43 < < X 4J k_ O X in X in O 3

4-J 03 c X >. < < 14- O 43 O O — T3 c E E 4J 43 43 43 E o in 3

4-J 4-> 3 43 43 O’ m CO m E 4J 2 03 >- CQ >- — 43 k_ CO Z CO X "O 03 4-

43E 43

O 43

X

—

X < 1- X 1-

43

X k- o

43CL LA vO rv. 43

33

Method
table

6

PRELIMINARY

TESTS

WITH

GROUP

I

SPECIMENS

z

o

o

(1) Q 4-> ^ LU 0) E

UJ E E

(D '—

O

<Q.

Q.rDo

o

>•o

C

</1 (U N

z: 3 X O CT''" — 0)

o

to ^

1- c

<u C3i

(Uuo<

COo

a.

oc

s,

3 1 c >*

4-^ 1 <n E — o o

c CO c t/i O T3 — c

(0 u 3 c O C •M (U (U L. 03 O <0 3

Q. ro E -3- O cr 3 CO t— 0> <l> -3* 0 -n o u <4- — 1- U o 03 <4- O a> M- -c •_ 0) 1— Q. O O -M C 0) V) to U “O — tn u 0) _c > X c CO c 2 c

fD (/) E u Q) L3 O ^ (0 0)

0) C (0 »

03 — m E 3 U 0) 03 4J in c •.i. in U 1. 0) C X 03 C 0) 3 o c O o. 1. o 4-J 1- C O > L. 0) 3

M- CNJ o •— •

o •- — 0) o. L. •M 3 34- +-» «— LA in X

-C u -C u 03 u

CD 03 (0

0) CM

0> CM CM O LA o

0) 0) (U 0) 03 — 0) 0) <u f— 03 03 <D 0) 0> 0)

L. L_ u 1- L. u i. 3- 3- L. u L. L.

0) <u (U 0) o 03 O 0) — 0) CM 0) o 03 >- 03 O) Q> ID 0) -C X -C X _C CM JC. JO X -C JC o.^ o. Q.^ Q. •« Q. •> Q.^ Ol s Q. •4 Q.»— Q.^ CL^ CL^ a »— </) ^ (/> vO in «— 1/3 vO in ^ to vO CM in f— to vO to t— in vD in »— in f— in LT\ o LA LA o LA LA LA r^ LA LA

-D O -O T— o o “D O "O o T3 O -o O *— a O o o X3 O T) o “O O D O “D

• • 03 • • 03 • • • CO • • r— 03 • • CO • f— • • o o o o 03 O o o 03 O o o o 0) o O 0 O 03 O 0 o <u o o o o o o

CD'-^ cn 03'^'^ C7) CD'—^ cn

O o u

03 03 10 oo ^ Q. oo Q. oo — Ql LA f— 03 -<-> LA T— CD 4-> 1— LA CO Lf

1 1 4-* 03 1 1 03 1 1 •M fo 1 O o 03 — o o <D

o O 0) ^ c

1- K E M- l- 1- E 14- 1- H E 14- H

Lj.

LiJ o Q c O

Q.

<D Q.

<U 03 o 5 03 o o o 3 o CM LA LA LA to *> LA

1 C CM CM CA O CM lA — 1 1 1 c o vO C 1 Csl £ O LA O •— CM »3 C LA

CM CM CA E O »- CM

CM 1 CM CA

LA LA

+1 +) O O

O O O •3 T— CM C T— LA I— CM CA CA +1 + 1

1

+1

1 c

+1 +1 +1 +1 , +1 -f u L. o

(U 0) •— U 1 1/) u •M 1 1 TD 3 <0 3 3 CD 03 1 —— C

-D C o o c -o * l- —

>- 03 CO — in •— 03 1/3 3 03 o o O

C Xi 1. c 03 03 03 u to c u in

n3 E 0) fO E V3 </3 — o — 03 03 > J- O > u O to *4- 03 03 o 0) 4-( o 1- o U3 03 C > c to > in -C 3 E O o 03 03 O 0) 0) M- i- 4-J V) L|- i_ O L3 c — 1- _o 4— • — o <u — -M o Q> 03 03 u

•— 2 c •— 1_ — 03 C Ql l- c c <0 •M L4- fO •M M- 03 O 03 ' O ID 03 o <u 4-1 3 — to ^ 3 •— > — 03 to — 1 > — 3 CO • Q. — C Q. Q. 4-1 ^ C 4-» cr <u * M Q. O 3 •M *Q. 1-3-0 O 03 O 3_ <0 0) Ql 3 E — o 3 E O 03 03 i_ o o 1. L. 0) O < •M O O < 34- Q. Q. 4-) 03 _l 14- 0) M- <

LAo

Ol

<u

0)5

E

I CM

I(U X)3

D.E<

3

^»
SUMMARY

OF

THREE

FIND

TRIALS

CONDUCTED

BY

SUPPLIER

ON

GROUP

II

SPECIMENS

FOLLOWING

NBS

TRIALS 1

THROUGH 7 c l- O o T3 to • 

>4- 03 c

4-1 -o 03 o 0) tn <0 E

0)

U 03 •i— <^P— o CM

4->

O in o 4-> 0) o c 03 to o to O- 0) to 4-4103i_Q. c i- in o o c O) •— 4- -o 03 c

4-1 OO 03 E •— o (U <T\"0 •— o C4 -3- 4-) (U l_ — 03 U <3^ -3" ro roi l_

4-< o 03 03 03

(U o to CL (0. o to to E c L. o o

•— 4-

4-) fO •— to

0) c

<u > c OO

O 03

<u f—

—— tM 03

(U —I +1 +) -H E oo O) < c o 4-> 1 CM 03 T3 Z o u

L. 4-) CM

O

>-

O

— c Q.

4-1 1 O ^ o s — TO 1-

(/) 03

C

N o O o o o

<3) 1_ 03 Z \D vD 03 03 03 x: o

LiO 4J 4-4 c

orCC 03 03 •—

— CD TO Z E c 03 o < O O 4-< •— to

4-1 E E E E o 0) 03 03 03 to

0) 4-» 4-) 4-1 4-1

4-> (/) to to to o

<u >> >- > >- •— o to to to to 4-t 03EO

4-1 3 • 03 C z 1 03

4-» T3

— E — O E — s >- a o 03 O o c c to 03 o 1— U E E CL x: 03 03 03 03 03 to to 3 Q. O M O 1 C Q. to O to O X) 03 O 03 O >«o O 03 Z o E O to •— in •— — 4-4

03

O > +-> 03

4-1 Q.

— to

l/l 03 o a >- c

(U 4-) c c — o

1- o r— E <31 E <3i 5 — 1 o 03 03 03 03 03 4-> 0) -C 3 — 4J o 4J O C 03

1_ to

C X) to o toO

Q. 03 03 >*IA >^LTV 03 03 E -M to —

to

— r—

to ce

(j to 03 -o i_

(U < CD

O 03

if) 4-

O

ZD E e E 03

O

03 03 03 4- Z 4-) 4-J 4-> to

<u in

m to C3 1 >~ > >' O

03 to in to E O

.C 03 to 4-> T3

toC

>< 0) to

03 o — o o

L. z sz

1- OO <rt o to

35
TABLE

8

DETECTION

SCORES

(IN

PERCENT)

FOR

TEN

TRIALS

WITH

GROUP

II

SPECIMENS

1

tt

i

I

i

I

I

i_ .

(U •— > ro o

GJ

O

<0 — <M e'p u

hU1c

l_ (U

(u e

JD 4- —

e o o

3 0 Z Qto

I0

s

X) ^ 0 C E — 0 G o 0 0

I- N

0 l_ a. 0 LO

r>^ -3- vO oo LA vO OO CM ro cr\ UTV LT\ CO CO vO CO LA -d" -3-

oo o vD vO -d" LA CA CM -d" -d" LA

CM ro LT\ -3- o CM vO CM LA -d" CO

CO oo o -3- o CA oo O CA -d*

csi CM LTV -3- CO \0 CM LA CO CO

CM OO vO -3- \0 CM O -d" CM

CM CM un o CM vO LA -3- CO

rr\ O vD CM (A OO

' O o

CO vD LA O CM CO \0 CM vO LO -3-

CN O LA CO CM vD LA vO CA LA

LA LA CM CA -3- lO CO VO -d- -3-

OO CM O vO CM O \£> CM vO -d" OO

CM CM LA O CM LA LA CM LA -3- CO

CM -3- -3- CA (A CM CO O CO

CM -3- vO CO CO v£) CM P>. LA -d"

cr\ CO o oo CO CM CO CA

ro CM vO LA CM CO vO CM vO CA CO

oo o^ vO \0 CM <r> CA oo LA

CM CO Uf\ LA CM CA CO vD CM vO vO -d-

(Tv o <A -d" -d" r- vO CM LA ro u\ vO vO CO -3- -3- \o LA vO LO

(TV vO O vO o -3- oo O -d" o irv LA LA LO -3- LA vO -d“ LA

ro -3- O CO -3- -3- -3- -3- OO ro -3" vD LA CO -3- -3- v£> -T vO -d" -d"

c/> UJ

00o

o oo OO OO OO CO OO CO oo OO oo oo toz

o LA vO —

•l LA CM fA LA •L CO 1— 0 0 0 CM o o CM 0 0 o u 1- 1. 0 > • • • • u u • UJ 0 0 0 ^ o o o O o 0 0 o h- 0 E E E E J1 JZ 1 E UJ

Q. o. Q. <— X D •> 3 •> 3 •> 3 X Q. a. c 3 «L o

(/) C 0 C 0 C 0 C (/) tfi O C 0

LT\ •— u •— u • — 0 LA vO 0 • — L. X) CM TJ LO X) O X> LA £ 0 E 0 E 0 E LA X3 CM o E 0 < — O — O »— ^ — O 3 JZ 3 jr 3 jC 3 0 O 0 O 0 o 3

O • O • o • O • >— Q. — a — Q. • 0 . 0 • *— Q. 00 o o> O o> o oi o 0 (/) rq </i 0 1/) 0 M- o — O — o tn 0 U) 1-
TABLE

9

CORRECTED

DETECTION

SCORES

(IN

PERCENT)

FOR

TEN

TRIALS

WITH

GROUP

II

SPECIMENSa

Over- a1

d-C o CM CA LA -a- M3 CA CA M3

LA LA CX3 CM LA M3 A LA M> M3 M3 _ <tj Q_ LA CA -a- LA A. CA CA M> A A O ^ O -d" -d" CO vO O CM LA M3 CA LA LA LA

<3 O

(X> un CO LA CM O O O CA LA CA o OO

h- CA M3 CM M3 M3 LA LA -d"

fO — cr\ d'9

L. vO oo CA CM OO O O CA OO CA A M3

t- CA CA oo M3 O CM -a- M3 LA LA -d"

«D — CO

1_ d£> lA vO CvJ CA OO O o CA LA LA A H lA -3- (A M3 O M> M3 -a- M> M> LA

DO ^ cNP <N \D CA CA CA CA M3 A O CA LA >O

lA LA CO CA M3 A. A LA A M3 M3

—

L. d'P lA LA CM oo O O CA M3 CA A LA

H- CA r>. <A o Mf CA M3 CA LA LA LA

(0 c>9 u \D CM LA LA o O CA M> CM -a- CM H CA cX> vO OO CM A- A M3 CA oo M3 M3

— lA

1. oM> lA CO CM CA O O LA M3 CA M>

y- UA CA <A M3 LA M3 A CA A -^r LA

fO — -cr u

oM> LA CA CA O O LA LA CA LA

h- -d" LA CX3 CA A^ A A -d- A A M)

H3 •-

v_ d'P CA CM LA oo O O LA M3 M3 OO

h- M3 M3 CA OO LA OO OO A CA A CO A

<0 — CM -^3- CA LA o o OO CM LA A

»- vO CO CM CA CO OO OO M3 LA A

<T3 LA CM CM CA o O o LA CA LA A OO

h- LA \£> CA M3 LA CO oo A A M3 LA M3

inC

i- (U

<U E

Numb of

pec i

— CA CM CA CM o o M) — A -d" CO LA M3

•L LA CM A. CA LA #• •L m

0) o 0) CM O O CM (U 43 o OO

&_ L. 1- (U . « • • • U LU LU

0) 0) 0) o O o o o <13 43 H“ oz

(U "c ' E — m E

s: m: JZ nj e E E E JZ x: E LU o Cl Q. Q. — X o « 3 « 3 « 3 X Cl Q. C 3 O o in in in M- C (U C (U C (U C in in O c 4) CO LA • — L- — U — L. 4) LA M> o •— u -J

•»-> <TJ <u D CM -D LA -a o -o LA E 0) E 0) E 0) E LA O CM T3 A E 0) CA < z — O — O — O 3 x: 3 m: 3 .C 3 (0 O <0 O <TJ O 3 X. — •— o

fD l_ Q_ <U (A o • o • o • o . — C3. — a — a • 43 . 43 • C3. • QC —

cn o CT) O U) o cm o ru lA (XJ in (X) in CD 4- o — O — O in (D in o h- 1-

for

an

explanation

of

this

table.
AGREEMENT

SCORES

(IN

PERCENT)

FOR

TEN

TRIALS

WITH

GROUP

II

SPECIMENS

IN

ACCORDANCE

WITH

THE

MODIFIED

CHARACTE R1

ZAT I

ON a

U '

<U

— > ro cr> -:r CT>

— CA o vO vO OO CO -d"

L0) »—

fD Q. U CO CA

Q-3

<u>

vO LA OO CA

CO o

OJ 1C sD rA 04 CA

V. vO Lf\ oo rA H

fO (T\ d'P vD CA AJ CA

1. vO LA OO CA

1-

fD CO d'P eg

— -=r CA

r- vO CA CA

hCO fD

CCi i- <5^ o CA -=r z (U vD OO oo LA >o —

fU o CA CA CA u vO LA oo OO CA

1-.

(D vO 04 CA o u 1^ OO LA

1-,

ir\ vD -T

v_ vD LA CA -a- 1-

fO -iT d^ 04 1^ CA CA vD U vO CO C30 LA

HfO d^ CA 04

L. CA OO

1-

fD d^> CA CA o U r-* OO oo LA

H1—Q

d^ 04 04 r--

L. O' CA vO

f-

</) c U <u

<u E

4- e o o 3 <u oo oo OO OO OO Z CL CO

LA

4-* •l LA 04

(D <u 0) (U 04

O

2:

u i_ (U . • “O (U (U 0) ^ o o D c e JZ _c CD E

0) E Q- Cl CL

—

X o •l

u '—

(/> {/) U) M- c 0) •— »— LA r— p— •— U

fU 0)

a 04 “O LA •a o TJ la E <u

i_

N

— o o —

O 3

(TJ L. o • o • o • o • CL

Q- (U CO O) o CD

O D1

O cn o TO {/>

LA CA vO o CO

O 04 oo vO o -cr 04 O LA

lD P-- vO sO vO lO

lD 04 vD -o* LA \0 LA vO MD

vO 04 o \o P^ CM LA lD LA LA Vl5 vO

CM p^ A- CM

O vD vO vO P^

CM vO -3- 04 LA

oo oo P^ p^

p^ -a- \D CA vO vO vO MD p^

CA CA CA 04 CA

oo CO 1^ vO oo p^ p^ coM

CD 04 F— CM lO oo N

vD 1^ LA vO • —

V.

(U

4-* u

(TJ l_

(D OA CA A> 04 CA vO _c oo oo vO p^ oo O

TJ

(U

CA CA p^ CA -a- » “D CO oo CA CO oo ot

(U s:

4~i

-a- CA CA CA p^ A- <A 4- CA OO 00 OO vO vO P^ oCo

4-* CDC

(A CA p^ CA PM P^ OO CD OO OO oo vO vO P^

CLX

QJ OO c

UJ (TJ oco L- OO OO oo CO oo OO o o

F— <) 4-

1- r— z • lD UJ CA

CA LA F. *L z o F— 04 (U (U LU (U • • • i. &_ LU (U o o o Q) (U oc oo E E E JZ jr E C3 (D 3 ^ 3 ^ 3 X CL CL c 3 < c <u C (U C (/) (/) o C (U — L- •— u (U p— LA vO o U -J E (U E 0) E LA TJ CM TJ P^ •— E 0) OA < 3 x: 3 JZ 3 (D o (0 O (D O F— 3 -C — — CL — CL • (U • (U • F— CL • OC

ro 1/) fD i/) (TJ 4- o —

O

—

O CA (D (/) o 1-
TABLE n

FIND TRIAL ON GROUP Ml SPECIMENS

Col . Col. 2 Col. 3

Specimen size, in. (mm), No. of

Specimen Description, Specimens

Seed Particle Composition and Shape,

Mass, yg

No. of Specimens

with Particle Detected

1 1/4x1 1/4 (32 X 32)

metal butterfly

gold sphere, 1

28

1x1 (25 X 25)

metal butterfly

gold sphere, 0.5

28

1 x 1 (25 X 25)

ceramic flatpack

gold sphere, 0.5

29

5/8 X 5/8 (16 X 16)

metal butterfly

gold sphere, 0. 17

27

TO-8

can gold sphere, 0.17

24

1x1 (25 X 25)

metal butterfly

gold wire, 0.5

4

5/8 X 5/8 (16 X 16)

metal butterfly

gold wire, 0.17

4

TO-8

can

gold wi re, 0.17

4

1-1/4 X 1-1/4 (32 X 32)

metal butterfly

no seed

4

1 X 1 (25 X 25)

ceramic flatpack

no seed

4

TO-8

can

no seed

4

TOTALS (seeded) 148

TOTALS (unseeded) 12

4

3

25

1

15

1

0

2

0

2

2

51

Col . 4

Detection Score

100 (col 3/col 4) , t

14

1

86

4

63

25

0

50

0

50

50

34

39

4 33
TABLE 12

TIME TO PARTICLE LOCK UP (s) AS A FUNCTION

OF ACCELERATION LEVEL AND FREQUENCY FOR A

SEEDED TO-18 SPECIMEN PACKAGE^

'“''^.^cclerat ion

^^|evel

Frequency^v^g' ) (Hz)

±3 +5 + 10

' +^20

20 13 k — —

Ao 17 8 1.6 1.0

60 20 20 8.4 1 .0

100 20 20 18.2 8.8

g

If the particle did not lock up, the test was terminated

at 20 s. The times are averages of five tests.

^0
FIGURE 1: Test configuration 1, incorporating commercial system components

(shaker and shaker control, ultrasonic detection transducer, detector modules),

threshold level detector built in-house in accordance with Test Method 2020,

and oscilloscope with camera.

^1
FIGURE 2: Test configuration 2, incorporating commercial system B components

(combination co-shock fixture and ultrasonic detection transducer with

amplifier, co-shock push-button switch, detector module with co-shock control),

shaker and shaker control, and oscilloscope with camera. The system B components are identified in table 1.

k2
FIGURE 3‘* Test configuration 3, for amplitude-frequency plots, incorporating

commercial system A components.

43
FIGURE k: Overall view of the NBS vibration exciter system, with various

commercial FIND apparatus. On the console table can be seen the pre-test

shock apparatus C (at 1); to its right (at 2) is a small control box with

a push-button switch for actuating the co-sh©ck apparatus, System B. Behind

these components (at 3) is the rack-mounted detector module of System B. Apparatus on the exciter is shown in close-up in figure 5 and identified in the caption for that figure. The two instruments at the right are the ex- citer power supply and controller for the System A exciter {h) and the

System A detector module (5).

kk
FIGURE 5: Close-up view of the NBS exciter, with various commercial FIND

apparatus. The System B co-shock fixture (6) is shown mounted on the armature

of the NBS exciter (7). A specimen device (8) is shown mounted on the System

B ultrasonic detection transducer (9). The manual co-shock tool (lO) used

with System A gives some idea of scale; it is approximately 150 mm long. The

System A vibration exciter sits to the right of the large exciter's armature

(at 11), with another specimen device (12) mounted on top of its ultrasonic

t ransducer (13)-

^5
a (a) TEST ACCELERATION LEVEL ±5 (d)

(c) TEST ACCELERATION LEVEL ±20 (f)

FIGURE 6: Photographs of oscilloscope screen traces generated at three test acceleration

levels by the amplitude-frequency plot technique for four T0~5 specimen packages

having different seed particles. For photographs a, b, and c, the seed is a gold

sphere 0.051 mm in diameter, and the deflection sensitivity is one volt per division.

For photographs d, e, and f, the seed is a gold sphere 0.102 mm in diameter, and the

deflection sensitivity is five volts per division. For photographs g, h, and i, the

seed is a lead sphere 0.076 mm in diameter, and the deflection sensitivity is one

volt per division. For photographs j, k, and 1, the seed is a lead sphere 0.152 mm

in diameter, and the deflection sensitivity is five volts per division. For all

photographs, the frequency scale is 25 Hz per division, and the svveep time represented

is 2 min. The enhanced trace levels in the region of 200 Hz (about two divisions

from the right-hand edge) seen in c, f, i, and 1 are the result of mechanical resonance of the coupler.

A6
TEST ACCELERATION LEVEL ±10 g

pP^q|Hpil''1l

"1

TEST ACCELERATION LEVEL ±20 g

FIGURE 6: Photographs of oscilloscope screen traces generated at three test acceleration

levels by the amplitude-frequency plot technique for four T0~5 specimen packages

having different seed particles. For photographs a, b, and c, the seed is a gold

sphere 0.051 mm in diameter, and the deflection sensitivity is one volt per division.

For photographs d, e, and f, the seed Is a gold sphere 0.102 mm in diameter, and the

deflection sensitivity is five volts per division. For photographs g, h, and i, the

seed is a lead sphere 0.076 mm in diameter, and the deflection sensitivity is one volts per division. For photographs j, k, and 1, the seed is a lead sphere 0.152 mm

in diameter, and the deflection sensitivity is five volts per division. For all

photographs, the frequency scale is 25 Hz per division, and the sweep time represented

Is 2 min. The enhanced trace levels in the region of 200 Hz (about two divisions

from the right-hand edge) seen in c, f, i, and 1 are the result of mechanical resonance of the coupler.
<

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FIGURE

7:

FIND

test

data

sheet.
FIGURE 8: Photographs of oscilloscope screen traces of shock acceleration waveforms imparted to the specimen by pre-test shock apparatus C (upper photograph)

and the system B co-shock apparatus, as sensed by a test accelerometer. For

both photographs, the deflection sensitivity is

time base 50 ys per division. Corrections that

in interpreting these photographs are discussed

1000 g per division, and the

have to be taken into account

in 3.3=1 and 3-3. 2.

^9
FIGURE 9: Photographs of oscilloscope screen traces generated at three different

times by the amp 1 i tude- f requency plot technique for the same specimen under the same test conditions. Comparison of the traces provides a rough check on the

repeatability of the technique and associated apparatus, as discussed in 3-^-

The specimen is a T0~5 package seeded with a gold sphere 0.051 mm in diameter.

The deflection sensitivity for the photographs is 200 mV per division, and tfie frequency scale is 25 Hz per division; the sweep time represented is 2 min.

The acceleration level was ±10 q .

50
(b) TEST ACCELERATION LEVEL ±10 go (e)

n

(c) TEST ACCELERATION LEVEL ±20 (f)

FIGURE 10: Photographs of oscilloscope screen traces generated at tliree test

acceleration levels by the amplitude-frequency plot technique for two diffetenL

package types, each with the same seed, a gold sphere 0.051 mm in diaiiieter.

For photographs a, b, and c, the specimen represented is a metal flatpack. For

photographs d, e, and f, the specimen is a T0-l8 package. For all photographs,

the deflection sensitivity is one volt per division, the frequency scale is

25 Hz per division, and the sweep time represented is 2 min. Gaps in the

trace are particularly evident in photographs e and f. These gaps each indicate

that the seed particle had become temporarily immobilized and represent delays

between the time the camera shutter was closed and the time the frequency

sweep was interrupted so that co-shock excitation could be imparted to the

specimen in an attempt to free the particle (see 3-^)-

51
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52

The

total

number

of

specimens

tested

is

given

in

parentheses.
APPENDIX I

trial 2

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OF

PIND

TESTS

ON

GROUP

II

SPECIMENS o

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53

The

total

number

of

specimens

tested

is

given

in

parentheses.
o c

LU o

Q.

—

CO 4J

(D

— l_ — 3

O) a. —

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The

total

number

of

specimens

tested

is

given

in

parentheses.
TRIAL k

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OF

PIND

TESTS

ON

GROUP

II

SPECIMENS o

LUOa

LUo

CM3

O)cooc

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<UI LOZoo<

a:

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u.>t/1 O

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0£. LU31—

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ca31

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ae

cu I 'H Lj z oe ^ LU o O 1 ^ LU lO

CDI t-o yee ^ LU z o 1—00 —

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— </> CD

i/l <

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0.

LCl

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a.

W)

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55

The

total

number

of

specimens
TRIAL 5

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OF

PIND

TESTS

ON

GROUP

II

SPECIMENS

TRIAL

CONDITIONS -

Frequency:

60

Hz

Acceleration: +

10^

Configuration: 1 a

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PARTICLE

SHAPE SIZE

(mm)

PACKAGE

TYPE

TO-3 TO

-5

TO-18

KLATPACK,

METAL

LID

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CERAMIC DIP

TOTALS

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SCORE

i-i)

56

The

total

number

of

specimens

tested

is

given

in

parentheses.
TRIAL 6

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OF

PIND

TESTS

ON

GROUP

II

SPECIMENS

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57

The

total

number

of

specimens

tested

is

given

in

parentheses.
o

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58

The

total

number

of

specimens

tested

is

given

in

parentheses.
TRIAL 8

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OF

PIND

TESTS

ON

GROUP

II

SPECIMENS o

LlJ UJ

t/>

<_> z oe ^ LU o o I ^ LU l/> Q

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UJ LA

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CL.

CM

CA

CM

CA

CM

CA

vO 00

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<T\ OO

CA

CM

CMOOA

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O

CJ oc: »—

LU LA X o

LU

C£. LA

LU CM X O

O-V)

O

CM

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vO OO

vO OO

CACA

CACA • O

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ACK, tC

LID o

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SCORE

(%) CO a. .1 Q- X X a. _J LA i- < K* <C ^ o < UJ 1 1 < H- < O' 1- H" o o _J UJ ^ UJ Ui o LU

u. j; LJ- o o 1“

O

O-<X

(D

59

Trie

total

number

of

specimens

tested

is

given

in

parentheses.
TRIAL 9

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OFPI

ND

TESTS

ON

GROUP

II

SPECIMENS

u

(-

o.

Q.3

CO c

<35 O+ 1

nj

<u

(Uoo<o

>-uc

(U3

CT

0)

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CJ<

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oX

3£o

s:o

Q.

t/1

COXaz

"T

LU

<_) z or LU o O (K> o ^ LU lO o

Ixl Zoz I LU o a: ^ LU Z O

l- o o ^ LU — to

Ul<1-o»-

LU

oc CO < LU 1 X • a. o

to to

UJ

a: vO

lUX o

a. • to o o<Ui LU

—1 a: LA

lU CU X O

a. • OO oX

tu

»— LA < LA CN| -J O • u. • O O

LU

a: fA

LU r— X • Q. o

3: l/> z__ LU z a: f— 3 LU LA X O < a. • o

LU LA

LU CM X O a. • to O X

LU r- LA

LA CM < O • • O Lx. O

LU

or

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to oJo Ul

cc *—

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a. • t/^ o

LU

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a. • to Oe

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LTV

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CM

CM

r<3

CM

O

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CM

CM

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lU

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I- • <

I-o

60

The

total

number

of

specirr.ens

tested

is

given

in

parentheses.
APPENDIX I

TRIAL

10

RESULTS

BY

PACKAGE

TYPE

AND

SEED

PARTICLE

OF

PIND

TESTS

ON

GROUP

II

SPECIMENS

TRIAL

CONDITIONS -

Frequency:

60

Hz

Acceleration:

^20 g

Suppl

ier

Tri

al

OO

Ui

UJ

«/> o

UJ

fO

u. 1 t-

(_) Z yQC ^ UJ o o o o o o o CM CM 1 O LU </> O 2 o <y\ o <n r- <n o cn o o^ O CTt .—a- o LA z 1 o

UJ Z

ocO ^ -4 UA * CM CA LA -a- -O’ 1— O o UJ — </> o

CM «sTV CA CA CA

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UJ

CC < UJ •- rr> o r^co CTv —1 X CA

a. o S,^

t/) (/> UJ

CC vO

lu

O CM CM (Tv C» o X o LA

a. • CO o o<UJ UJ

CC Lf\

O CO CM o o o LAC» CO

UJ C>l C'J X O

O. « 00 OX

UI

Vl r- Lf\ < LAO • U. * O

CA rA CO o »- cx> vO

O

UI

CC fA X • r— CM o CM o CO CA

o. o CA

X. c/>

UJ

X.

X *- UJ lA o _ o o o CM CO

_J

XO < O.to O

UI

CC LA

LU CM o o o o o o O CO

O

XO

O. • to O

>< LU LA

LA CM o cr> CM o CA o CO CO -0" < o • ~J • o u. o

UJ

VC

O

LU CM CA CTvOO o X • LA

CL

O

CO

_i

c> LU

CC •- y—>S UJ LA CM o o LA CO OO X O Q-tO O

CM

LU

CC LT» jO-^ LU CM O oo o o LAOO CO X o

CLOO

O

CM

LU

OC e o

UI <-) a. o to

>- * o .1 z

x;

— se o

_J LU CU ^ o o o — c,>? o O < < ~ — to h- LU 00 Q. -J CL X X Cl _l o

h* CL UJ rA lA t- < < — LU

o: < M 1 1 1 i 1- or o h h“ X — o o o ^ LU -J UJ LU o LU

Cl to CO dI 1- H U.

X Ll o LJ 1- O

61

The

total

number

of

specimens

tested

is

given

in

parentheS'
NBS>1I4A (REV. ••7*>

U.S. OEPTo OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS IR78-1590

7. AUTHOR(S) John S. Hilten, Paul S. Lederer, J.

Mayo-Wells, and Carol F. Vezzetti

Franklin

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

4. TITLE AND SUBTITLE

Loose-Particle Detection in Microelectronic Devices

5. Publication Date October 1978

8. Performing Organ. Report No. 722

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Str-t, city. Stste, ZIP)

National Aeronautics and Space Administration

Goddard Space Flight Center

Greenbelt, Maryland

13. Type of Report & Period Covered NBSIR - July, 1977 to

15. SUPPLEMENTARY NOTES

1 I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

II. /^TRACT (A 200‘wom or looa tectuaf muaanmry of momt mlgnltiemnt inlotmmtion. It document tneludaa a aignilleant bibliography or

lllaratura auraay, mantion It harm.) The work described consititutes an evaluation of the test procedures and

apparatus specified in MIL-STD-883, Test Method 2020, Particle Impact Noise Detection

Test. The major experimental effort described — a comparision of procedures and

apparatus — is based on the use of specially prepared specimen device packages known

either to have or not to have a particle present. Other experimental efforts

reported include characterization of the accelerations imparted to a specimen device

by pre- and co-shock apparatus, a brief study of the effectiveness of couplant

materials in transmitting mechanical energy to the specimen device, and a comparison

of the output signal level from four different ultrasonic detection transducers

under otherwise identical test conditions. As part of the plan of work, 252 of the

specially prepared devices, representing six package types, were characterized (as

containing particles or not) by several test procedures in order to provide a set

of specimens for use by the sponsor in a proposed interlaboratory evaluation of

FIND testing. Problems associated with this effort are discussed. Results of the

work are presented, together with conclusions and recommendations for further work.

A result of interest is that the acceleration imparted by the single sample of the

pre-test shock apparatus tested is on the order of 1.5 times the maximum specified

by the Test Method.

17. KEY WORDS (al* to Iwalaa anirlaa; miphabatical ordar; capitallaa only tha tirat lattar ol tha tirat kay word unlaea a proper name;

aaparaiad by aamieoiona) omission; couplant j co-shock; detection; electronic

package; impact noise; microcircuit device; particle detection; particle impact

noise detection; FIND; pre- shock; seeded specimens; transducer.

18. AVAILABILITY Unlimited

nflafipf Official Distribution. Do Not Release to NTIS

r I Order From Sup. of Doc., U.S. Government Printing Office. Washington, DC

20402, SD Stock No. SN003-003-

[2J Order From National Technical Information Service (NTIS), Springfield,

VA. 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

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22. Price

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