Semiconductor
Assembly
Materials Science

Solder Fluxes

Solder Pastes• Flip-Chip Flux

• Die-Attach Paste

Polymers/
Underfills• Ball Attach Flux

• LED Mounting Paste• Epoxy Fluxes• Wafer Flux

• Au/Sn Paste• No-Flow Underfills• PoP Flux

• Indium Alloy Paste• Substrate Paste• Conductive
Adhesives

Metal TIMs

Solder Wire

Solder Preforms• Compressible• Fluxless Die-Attach(SSDA) Grade• LED• Heat-Spring™
• Liquid Metals• Pb-Free Wire

• Seals• High-Pb Wire

• Package-on-Package(PoP)

Solder Spheres• 0.1 to 0.76mm• Pb-Free Spheres• High-Pb Spheres

Other Brochures Available:• PCB Assembly Materials• Thermal Interface Materials• Engineered Solders• Lids2

Applications•B ump fusion
wafer fluxes• Flip-Chip fluxes• Package-on-Package• Ball Attach

Power
Semiconductors• Lead frame andhybrid assembly• Die-Attach solder paste• Die-Attach solder wire
• Die-Attach solder
preforms

Semiconductor Packaging

Semiconductor
Packaging

WL CSP
Flux

Singulation

Wafer
Bumping

ThermalManagement

Wafer Flux
Wafer Paste• Metal TIMs
• Shims/Preforms• Compressible alloys• Liquid metals• 86 W/mK conductivity•A ccommodates
CTE mismatch

Engineered
Solders• Fluxless Die-Attach• Hermetic sealing• Pin soldering• Other speciality

Die-Attach

Dispense

Die-Attach
Wire• Stencil print• Wave solder• Pin-in-Paste+• Underfill

www.indium.com• Solder TIMs
• Rework & repair• Package-on-Package• System-in-Package

LED
Manufacture

PCB Assembly
Au/Sn
Solder Paste
Au/Sn Preforms

3

Thermal Interface
Material

Singulation

Micro
Spheres

Flip-Chip
Flux

Direct Chip
AttachBall
Attach Flux

WL
Underfill

SolderSpheres

Capillary Underfill
No-Flow Chip
Underfill

Ball
AttachTIM 1Underfill

Package-on-Package(PoP) Assembly

Substrate
Bumping
Substrate
Paste

Dispense

TIM 2

Die-Attach
Solder Paste

PoP
PastesReflow

PoP
FluxesKey
Commercial
Materials
Developmental
Materials

To request a full-size copy of this poster, please email askus@indium.com
askus@indium.com

4

Wafer Fluxes
Introduction
Indium Corporation’s Wafer Fluxes are low-viscosity(typically less than 120cSt) rheologically-optimized
Semiconductor-Grade liquid fluxes. Wafer Fluxes
are applied to the surface of wafers after either asolder-deposition process (usually plating), or bumpdeformation after known good die (KGD) probe testing.

Key Performance Needs:• Bump co-planarity and singularity•C onsistent bump shape across the wafer surface•N o “wraparound” (wafer backside contamination)• No delamination during subsequent
underfill operation (good cleanability)• No UBM corrosion

Application Note: Cleaning
Solvent-clean materials may be cleaned witheither mesitylene, terpene-based material, or asemi-aqueous solution.
Water-soluble materials are optimized to be cleaned
with deionized water at room temperature.

Wafer Flux Product Selector
Compatible Alloys
Product
Name

Cleaning
MethodApplication
MethodFlux
Designation (1)HalideFree

SAC
AlloysHigh Pb& Au/Sn

63Sn

SC-5R

Solventclean

Spraying /spincoating

ROL0

Yes

Yes

Yes

WS-3401 Watersoluble

Spraying /spincoating

ORM0

Yes

Yes

WS-3543 Watersoluble

Spraying /spincoating

ORM0

Yes

Yes

(1) Per ANSI/IPC
TM650: J-STD-004

www.indium.com

Reflow
Atmosphere

Wafer
Diameter

Used in
HVM (2)

Yes

Nitrogen(<20ppm O2)
or 4%H2/N2

100-300mm Yes

No

Yes

Nitrogen(<20ppm O2)
or 4%H2/N2

100-200mm Yes

No

Yes

Nitrogen(<20ppm O2)
or 4%H2/N2

100-300mm Yes(2) High Volume
Manufacturing

5

Flip-Chip Fluxes
Introduction
Indium Corporation’s Flip-Chip Fluxes are moderate
viscosity fluxes (typically 50cSt to 100kcps) used
to solder a bumped or copper-column flip-chip to a
substrate in the direct chip attach (DCA) process.
The substrate pads may be metallized/OSP-bearing,pre-bumped with solder, or printed with substrate paste.
Flip-Chip Fluxes are typically applied by either
spraying, dipping, or a combination of spraying
and dipping.

Key Performance Needs:• Controlled and time-stable rheology• Particle-free spray• Homogeneous dip• No part movement during reflow• Consistent solderability• Reflow at 5 — 25ppm O2 in nitrogen• Process compatibility:• High and low reflow temperatures

too low to allow cleaning, so low-solids no-clean fluxes
are preferred.

• Cleanable (water-soluble) or
Epoxy-compatible (NC/EP)

Application Note: Underfill Compatibility
As the number of I/Os in CPUs and GPUs moves above
5,000, the most common technology for water-soluble
fluxes is either a higher-solids spray flux (such as
WS-3500), or a combination (such as WS-3500 and the
WS-367). Above 10,000 I/Os, clearances are typically

The compatibility of fluxes with subsequent underfill
processing is dependent either on the cleanliness of
the area under the chip (water-soluble fluxes) or thecompatibility of the residue with the underfill material(no-clean fluxes). Testing has shown that underfill
compatibility with no-clean fluxes is a combined functionof the reflow process, underfill curing process, andunderfill chemistry.

Flip-Chip Flux Product Selector
Compatible Alloys

Product Name

Cleaning
MethodApplication
Flux
HalideMethod
Designation (1) Free

SAC
AlloysHigh Pb& Au/Sn

63Sn

Residue %Used in
HVM (2)

WS-3500

Water-soluble

Spray

ORM0

Yes

Yes

Yes

Yes

n/a

Yes

WS-367

Water-soluble

Dipping

ORH1

No

Yes

Yes

Yes

n/a

Yes

FC-NC-HT-A1

No-clean

Spray

ORLO

Yes

Yes

Yes

Yes

< 1%

Yes

NC-510No-clean

Dipping

ORLO

Yes

Yes

No

Yes

4%

Yes

(1) Per ANSI/IPC
TM650: J-STD-004(2) High Volume
Manufacturing

askus@indium.com

6

Ball Attach Fluxes
Introduction
Indium Corporation’s Ball Attach Fluxes are viscous fluxes(typically 100kcps to 1000kcps) used to attach solder
spheres to the bottom of ball-grid array (BGA) packages.
We offer a variety of materials, suited to specific processneeds, from halide-free water-soluble fluxes to no-cleanmaterials suitable for wetting nickel.

Key Performance Needs:• Particle-, crystal-, bubble-free• Homogeneous• Controlled and time-stable rheology• Consistent solderability• No part movement during reflow• Reflow in air• Wetting onto a variety of metals:
copper, ENIG, bare nickel• Cleanable, even after high temperature
air reflow

Application Note: Pin Transfer
Ball Attach Fluxes are typically applied to packages
using the pin-transfer process. An array ofspring-loaded pins is immersed in a doctor-bladed
flux reservoir of a particular depth. The pins arethen pushed onto the bottom of the BGA package totransfer the flux. Solder spheres are then placed in
the flux deposits and the package is reflowed.

Ball-Attach Flux Product Selector
Compatible Alloys
Product
Name

Cleaning
MethodApplication Method

Flux
HalideDesignation (1) Free Sphere Size

WS-3600

Water-soluble

Pin-transfer / Printing

ORH1

No

>0.30mm

WS-3622

Water-soluble

Pin transfer / Printing

ORH1

No

WS-366

Water-soluble

Printing / Pin-transfer

ORH1

WS-364

Water-soluble

Printing / Pin-transfer

NC 506

No-cleanNC-414High Pb& Au/Sn

63Sn

Residue
% (2)

Yes

No

Yes

None

≤0.30mm

Yes

No

Yes

None

No

Any

Yes

Yes

Yes

None

ORM0

Yes

Any

Yes

Yes

Yes

None

Pin-transfer / Printing

ROL1

No

Any

Yes

Yes

Yes

26%

No-cleanPrinting / Pin-transfer

ROL1

No

Any

Yes

No

Yes

48%

NC-026

No-clean

Pin-transfer

ROL0

Yes

Any

Yes

No

Yes

5%

NC-007

No-cleanPrinting / Pin-transfer

ROL1

No

Any

Yes

Yes

Yes

47%

(1) Per ANSI/IPC
TM650: J-STD-004

www.indium.com

SAC
Alloys(2) Approximate
residue level7

Water-soluble Solderability Table
Solder Alloy
Metallization

52In/48Sn

ENIG

WS-366

Immersion Silver

WS-364WS-366WS-366WS-366WS-3600
WS-3611
WS-3600
WS-3611
WS-364WS-364WS-366WS-3600
WS-3611
WS-364

CopperOxidized Copper
NickelOSPAlloy 42

Sn/Pb

SAC 387

WS-3600
WS-3611
WS-3600
WS-3611
WS-364WS-366WS-366WS-363WS-366WS-366WS-3600
WS-3611

WS-3600
WS-3611

WS-3600
WS-3611
WS-3600
WS-3611

WS-366WS-366

No-clean Solderability Table
Solder Alloy
Metallization

52In/48Sn

ENIG
Immersion Silver
CopperOxidized Copper
NickelOSP

NC-414NC-414NC-414NC 506NC 506NC 506
NC-414NC 506

Alloy 42

Sn/Pb

Indium Corporation fluxes offer two cost-saving
process opportunities:
1. Although water soluble fluxes are currently
favored by the Semiconductor Packaging industry,
significant capital equipment and process costsavings can be obtained from the use of Indium
Corporation no-clean materials.
2. By using clean bare nickel instead of Au/Ni, theexpense of gold-plating can be avoided.

Award-Winning:
Excellence in Semiconductor
Packaging: NC-500 Series
Our NC-500 Series Ball Attach
Fluxes outper form all others
in five key areas:• Innovation• Quality

SAC 387

NC-414NC 506NC 506NC 506NC 506NC 506
NC-414NC 506

Value-Added:
No-Clean Ball Attach Properties

NC-414NC 506NC 506NC 506NC 506NC 506NC 506• Speed/throughput
improvements• Cost-effectiveness• Environmental
responsibility
See why
one major NC 506 user said, “We cannot
replace this flux from Indium Corporation.”

NC 506 and Alternative Fluxes:
Wetting onto Nickel
Reflow
Atmosphere
Air

Comments: (3)Used in HVM (4)Red color for pre-reflow
inspection; automated level
detection (3)Yes

Red color. Designed forsmaller spheres. High Tack

Yes

Air

Clear before reflow

Yes

Air

Halide-free

Yes

Air

Industry-leading material.
Wets to oxidized nickel

Yes

Air

Wets to nickel

Yes

Nitrogen(<100ppm
O2)

Halide-free. Ultralow residue. Not Yet
Underfill compatible

Air

Good for high temperaturealloysYes(3) For example:
Zen Voce model ZVM380(4) High Volume
Manufacturing

Air

180
160
140

SAC 387

120

Sn/Pb

100

88Pb/10Sn/2Ag

80
60
40
88Pb/10Sn/2Ag

20

Sn/Pb

0
Competitor

Flux # 1

SAC 387

Flux # 2

NC 506askus@indium.com

8

Die-Attach Solder Pastes
Introduction
Although there are four major processes for die-attach (seetable for comparisons), solder-based processes are still
the most popular, as they provide high reliability with easeof processing. Indium Corporation’s Die-Attach Solder
Paste is typically a dispensable, high melting-point solder
paste, which is reflowed in forming gas (H2/N2 mix).

Key Performance Needs:• Low voiding in reflow• Long dispense life
• No tailing• No separation• Bubble-free packaging• Residue-free cleaning or residue
compatible with overmolding process

Applicable Alloys:
Alloys used in die attach processes vary, depending on the
manufacturing process requirements and end-use needs. A
partial list of alloys often used in the die-attach process isgiven in the Die-Attach Solder Paste Alloys Table.

Processes for Die-Attach
Variables

Metal-Filled Polymers

SolderEutectic Bond

Metal / Frit

Material stability
Automated application
Curing / Processing
Compatibility
VoidingService life
Thermal / Electrical conductivity
CTE mismatch
Key: Good

Some Issues

Problematical

Die-Attach Solder Paste Product Selector
Product
Name

Metal
Flux
Residue
Load Designation (1) Level

Cleaning

Reflow
Atmosphere

Application

Used in
HVM (3)

Indium9.72 88.5% ROL1

< 5%

Aqueous cleaning
solutions known

Forming
Gas (2)Ultralow voiding, even on the largest
packages. Long dispense life. Long
cleaning bath life

Yes

Indium9.52 87.0% REL0

2%

Designed to be
no-clean. Cleaning
solutions known

Forming
Gas (2)

Low voiding. Light colored and extremely
hard residue. Does not wet edges of
unpassivated die

Yes

Indium9.32 89.0% ORL0

0.4%

Aqueous cleaning
solutions known

Forming
Gas (2)Ultralow residue. Minimal voiding whenused with small die

Yes(1) Per ANSI/IPC
TM650: J-STD-004• All dispense-only products• All Indalloy 151: 92.5Pb/5.0Sn/2.5Ag• Type 3 powder (-325/+500mesh)• Minimum dispense needle is 20 gauge

www.indium.com(2) 96%N2, 4%H2

(3) High Volume
Manufacturing

9

Die-Attach Solder Paste Alloys
Pb-free:

SolidusLiquidusIndalloy 121 (96.5Sn/3.5Ag)

221˚C Eutectic

Indalloy 133 (95.0Sn/5.0Sb)

235˚C

240˚C

Contains antimony

Indalloy 209 (65.0Sn/25.0Ag/10.0Sb) 233˚C Eutectic

Pb-based:Comments
Automotive usage
J Alloy: contains
antimony

SolidusLiquidusIndalloy 150 (81.0Pb/19.0In)

260˚C

275˚C

Good thermal cycling

Indium9.72 Solder Paste

Indalloy 151 (5.0Sn/92.5Pb/2.5Ag)

287˚C

296˚C

Industry standard forsolder paste

Although each Indium Corporation die-attach paste hasa unique niche, Indium9.72 is by far the most versatilematerial. The dispense life of this is very long (seeFig. 1). By adjusting the reflow profile to minimize voiding,
yet avoiding the formation of intermetallics (see Fig. 2), ahigh reliability joint can be consistently produced.

Indalloy 159 (10.0Sn/90.0Pb)

275˚C

302˚C

Automotive

Indalloy 163 (2.0Sn/95.5Pb/2.5Ag)

299˚C

304˚C

Wire alloy, low Sn

Indalloy 164 (5.0In/92.5Pb/2.5Ag)

300˚C

310˚C

Good thermal cycling

Indalloy 165 (1.0Sn/97.5Pb/1.5Ag)

309˚C Eutectic

Wire alloy, low Sn

Indalloy 171 (5.0Sn/95.0Pb)

Mass of solder dispensed /grams

Figure 1
Indium9.72 Solder Paste Dispense Life

10
9
8
7
6
5
4
3
2
1
0

15 8.737
30 8.835
60 7.779
90 7.564
150 6.9
180 6.129

0

9.038
8.967
7.8
7.617
7.091
6.044

100

200

8.962
9.039
7.843
7.599
6.837
6.217

308˚C

312˚C

Automotive, wire

Indalloy 228 (10.0Sn/88.0Pb/2.0Ag) 268˚C

290˚C

Poor thermal cycling

Indalloy 233 (5.0Sn/85.0Pb/10.0Sb)

256˚C

Step soldering usage

Figure 3
Au thickness(on Ni or Pd)

200ms #3
300ms #1
300ms #2
300ms #3

500

240˚C

Factors Affecting Voiding

8.912
100ms #1
8.947
100ms #2
7.807
100ms #3
7.593
200ms #1
6.943
200ms #2
6.130

300
400
Time / minutes

Phosphorus
level (Ni)600

H2 absorption(Ni or Pd)

Metallization

Large

Die

Size

Figure 2
Solidus
too high

Indium9.72 Solder Voiding Failures versus
Peak Reflow Temperatures

Alloy
Choice25%% of Parts Failing due to
Voiding

Too Large

Solder
Paste

20%
Deposit Size

All voids

Too Small

Single voids

Flux Activity

Leadframe

Contamination
Oxide

15%

Comments

Organic

Voiding
Too coolToo High

Reflow

Metal loading
Too Low

ProfileAtmosphere

10%
Too Low

5%
0%
300

310

320

330

340
350
Temperature (˚C)

360

370

380

390

Application Note: Voiding
Voiding is a function of many different parameters in
the process, as can be seen from the voiding diagram(see Fig. 3). Die-attach solder paste should be handled
carefully, particularly with high-Pb pastes, which are
more sensitive to storage at ambient temperatures. The
reflow atmosphere diagram (see Fig. 4) illustrates typicalatmosphere needs for high-temperature reflow processes.

Nitrogenonly

Forming gas(H2/N2)

ExcessiveoxygenInsufficienthydrogen

Figure 4
Reflow Atmosphere Requirements
versus Reflow Temperature

ppm O2
in N2
100

10

Nitrogen(N2)

Forming
Gas (H2/N2)

1

250

300
Peak Reflow Temperature (˚C)

350

askus@indium.com

10

Die-Attach Wire
Introduction
Indium Corporation’s Die-Attach Wire (or SSDA [soft solder
die-attach] wire) is a fluxless solder wire used to effectdie-attach. SSDA grade wire will result in higher yieldsof an improved quality product with fewer interruptionsin production.

Key Performance Needs:• Ultralow oxide (wire sur face and in wire)• High alloy purity• Precise and consistent wire diameter• Tight alloy chemistry control

Application Note: SSDA Wire versus
Standard Grade Wire
Indium SSDA grade solder wire differs from standard grade
solder wire in three principal ways:
First, elements with a purity ≥99.95% are used to produce
Indium Corporation SSDA wire alloys. This wire proves
to be among the highest purity in the industry by actual
comparative analysis. This assures that the alloy melts
without producing slag (from various impurities), to deliver
more uniform wetting. Further, there is no clogging of
the spanker or buildup of slag in other areas, minimizing
interruptions in production.
Second, the oxide content on the SSDA wires surface andinterior is minimal. This is achieved by a combination of
the use of high purity raw materials, as discussed above,
but also by inert gas, shielding of the process, particularly
during the spooling of the final package. The spool is thensealed in a metallic envelope, also under inert gas, toprevent diffusion of air into the package during storage. A
clean, oxide-free wire allows smooth production of molten
solder that wets better and more uniformly, consistently
producing nearly void-free solder joints.
Third, and finally, the use of an inert gas-shielded
extrusion process, monitored with laser micrometers,
allows production of Indium SSDA wire of 30 mil (+0.762mm) diameter with a maximum variance of only 0.786 mil(+0.02 mm), compared to the variance of standard wire,
which is typically +2mil (+0.05mm).

www.indium.com

Standard Wire Diameters
Diameter*Tolerance

0.762mm (0.030 inch)+/ 0.020mm (0.008 inch)

0.508mm (0.020 inch)+/ 0.020mm (0.008 inch)

0.381mm (0.015 inch)+/ 0.020mm (0.008 inch)* Indium Corporation is a custom manufacturer: smaller and larger diameters are available.

Alloys for Die-Attach Solder WirePb-free:Indalloy 133 (95.0Sn/5.0Sb)

SolidusLiquidus

235˚C

240˚C

Indalloy 209 (65.0Sn/25.0Ag/10.0Sb) 233˚C Eutectic

Pb-based:Comments
Contains antimony
J alloy: contains
antimony

SolidusLiquidusIndalloy 150 (81.0Pb/19.0In)

260˚C

275˚C

Good thermal cycling

Comments

Indalloy 151 (5.0Sn/92.5Pb/2.5Ag)

287˚C

296˚C

Industry standard forsolder paste

Indalloy 159 (10.0Sn/90.0Pb)

275˚C

302˚C

Automotive

Indalloy 163 (2.0Sn/95.5Pb/2.5Ag)

299˚C

304˚C

Industry standard
for wire

Indalloy 164 (5.0In/92.5Pb/2.5Ag)

300˚C

310˚C

Good thermal cycling

Indalloy 165 (1.0Sn/97.5Pb/1.5Ag)

309˚C Eutectic

Wire alloy, low Sn

Indalloy 171 (5.0Sn/95.0Pb)

308˚C

312˚C

Automotive, wire

Indalloy 228 (10.0Sn/88.0Pb/2.0Ag)

268˚C

290˚C

Poor thermal cycling

11

Metal Thermal Interface Materials
Introduction
Metal Thermal Interface Materials radically improve:•H eat dissipation efficiency in electronic devices• T hermal conductance for high power devices with power
densities in excess of 50W/cm2•E nd-of-life performance at the thermal interface – to avoid
failures common with fluidic solutions such as greases•P ortable device battery performance – by reducing
thermal resistance and cooling fan size•P
 ortable device use profile – by reducing heatsink size
and mass•C ompliance with RoHS while accommodating step
soldering requirements
Indium Corporation has solutions for:• Telecom• Medical• Computing• Cryogenics• Semiconductors• Automotives• LEDs• Power devices• Photonics

Applications
Some non-confidential applications include:• Semiconductor integrated circuits• Power QFNs
• Power device to PCB attach (TO220, etc.)• Telecom• Die-Attach (Photonics, MOSFETS, LED etc.)• Laser diodes

90°C

80°C

Packaging• Au/Sn solder• In/Pb solders• Pure In• InFORMS®
• Sn/Pb solders• SAC Pb-Free solders• Tape & Reel
• Syringe• Bottle• Custom packaging

Metal Properties
Indalloy
NumberMaterial

ThermalConductivity(W/mK)

100In

4

86

97In/3Ag

290

73

90In/10Ag

367

Liquidus(°C)

Solidus(°C)

157 (mp)157 (mp)143 (Eutectic)
237

143

91Sn/9Zn

201

61

199 (Eutectic)

52In/48Sn

1E

34

118 (Eutectic)

Types of Metal TIMs:
1. Solderable
2. Compressible
3. Liquid
4. Low-Melting Alloy

70°C

60°C

1500 Hr. @ 90°C

1500 Hr. @ 90°C

Heat-Spring™

Baseline
Thermal Grease(Device runs cooler)(Device runs hotter)

Lower temperatures confirm the superiority of Indium
Corporation’s Heat-Spring™ TIM vs. thermal grease.

Thermal Resistance (cm2 – °C/W)

Products

Thermal Resistance
0.20

Thermal Grease #1 (2 mil)

0.19

Thermal Grease #2 (2 mil)
3 mil Indium Foil

0.16

3 mil HEAT-SPRING™

0.14
0.12
0.10
0.09
0.06
0.04
0.02
0.00
0

20

40

60

80

100

120

140

160

180

200

Pressure (psi)Superior Performance: Heat-Spring™ provides reduced
thermal resistance at reduced clamping pressure.
askus@indium.com

12

Solder Spheres
Introduction
Indium Corporation produces spheres with accurate
diameters; shiny surface finishes; and highly sphericalshapes. Our spheres are made in dedicated manufacturing
cells supported by Statistical Process Controls (SPC).
All spheres are made from pure metals, combined to
produce exact alloy compositions. After forming, spheresare classified by size using an automated, high capacity
process that results in smooth, bright surfaces.

Key Performance Needs:• High purity alloy• Roundness (sphericality)

Advantages• Accurate diameter•N on-clumping

Indium Corporation solder spheres are used by Semiconductor
Packaging companies around the world. Our customers tell us that
we offer the following advantages over competitor solder spheres:•N on-darkening

Standard Solder Materials:• Consistent shininess allows ease of automated inspection• 99.99% In• Use of pure alloy guarantees consistent reflow and wetting• 63.0Sn/37.0Pb• Copper limits tighter than J-STD-004 for SAC alloys• 62.0Sn/36.0Pb/2.0Ag• SAC405: 95.5Sn/4.0Ag/0.5Cu• Homogeneity of alloy within each solder sphere, fromour unique manufacturing process• SAC305: 96.5Sn/3.0Ag/0.5Cu

Standard Sizes:• SAC387: 96.5Sn/3.8Ag/0.7Cu• 0.300mm (12mil) to 0.760mm (30mil)

Microspheres

Figure 1

Microspheres are solder spheres that have a diameterof 0.3mm (12mils) or less. These are finding a variety ofniche applications in areas as diverse as MEMS; LEDs;
and increasingly in wafer-level packaging.
Our capabilities
include the
manufacture ofspheres of almost
any alloy (including
Au/Sn) down to0.1mm in diameter,
at an unmatchedtolerance of +/- 5%.
Figure 1 shows
4mil diameter gold/
tin eutectic spheres. Figure 2 shows our ability to meet thetolerance needs of our most demanding customers.

Figure 2

OnewayAnalysis
MeasureBy Supplier
One-way
Analysis ofof Measure
By Supplier
0.0041

Microspheres
In (99.99%)
52In/48Sn
97In/3Ag
80Au/20Sn
SAC387
SAC405
SAC-M01
SAC-T002
www.indium.com

Application
Various MEMS
Various MEMS
WL-CSP (Hi-rel)
MEMS
Various
WL-CSP (Hi-rel)
Mobile electronics
Mobile electronics

0.0039MeasureProduct

0.004

0.00380.00370.00360.0035

IndiumCorporation

Competitor
1

Attribute=Diameter

Competitor213

PastesSubstrate Pastes
Introduction
Indium Corporation’s Substrate Pastes are nitrogen reflow,
no-clean solder pastes made with Type 5 and Type 6
powder, which are specifically formulated for flip-chip
attachment and CSP and wafer bumping applications.
The flux is compatible with Sn/Ag and Sn/Ag/Cu alloy
systems. Sn/Pb is also available. Substrate Pastes
provide consistent volume deposition, low solder balling,and high yields. If cleaning is needed, the flux residue
may be removed with commercially-available cleaners.

Key Performance Needs:

Substrate Pastes
Mesh Size• Ultra fine-pitch printing• Compatible with all common Sn/Pb and Pb-Free Alloys• Consistent volume deposition• Superior yields• Excellent paste release• Smooth and shiny joint appearance

Type 5

Type 6

Product
CP-5241
CP-5246
CP-5256
CP-5121
CP-5106
CP-6241
CP-6246
CP-6256
CP-6121CP-6106

Alloy
95.5Sn/3.8Ag/0.7Cu
95.5Sn/4.0Ag/0.5Cu
96.5Sn/3.0Ag/0.5Cu
96.5Sn/3.5Ag
63.0Sn/37.0Pb
95.5Sn/3.8Ag/0.7Cu
95.5Sn/4.0Ag/0.5Cu
96.5Sn/3.0Ag/0.5Cu
96.5Sn/3.5Ag
63.0Sn/37.0Pb

Metal Load

Particle Size

89-89.5%

15-25 µm

89-89.5%

5-15 µm

Eutectic Au/Sn Solder Pastes
Introduction
Eutectic Au/Sn (80Au20Sn) has a melting temperature of
280°C (556°F). It can be made into solder paste form withvarious options to address specific applications. Au/Sn solder
paste is generally used in applications that require a highmelting temperature (over 150°C), which requires a hardsolder alloy. It is also used in applications that require a hightensile strength and high corrosion resistance, or in step
soldering applications where the solder can not melt duringa subsequent lower temperature reflow process. For thesereasons, Au/Sn solder paste is an ideal solution for military,
aerospace, consumer, and medical applications. In addition,
Au/Sn solder paste yields are usually above 99.5%.

Adjust Metal Loading By:
Powder:• High temperature solder• Maximum solder joint strength• Compatible with other precious metals•S uperior thermal conductivity when compared tostandard solders• Excellent wetting

Printing

Dispensing

25-45 microns

0.0%

0.0%

Type 415-38 microns

-0.5%

-0.5%

Type 515-25 microns

-0.5%

-1.0%

Type 6

5-15 microns

-1.0%

-1.0%

Recommended Reflow Profile:

Dispensing

350
300
250
200

Liquidus 280 ˚C

150
100
50
0
0

Au/Sn solder paste is formulated for automated high-speed,
high-reliability, or single- or multi-point dispensing equipment.
It also functions well in hand-held applications. Highly accurate
volumes can be dispensed using either pneumatic or positive

Powder Range (4):Type 3Temperature (˚C)

Key Performance Needs:

Variation of Metal Loading vs. Powder Size

1

2

3

4

5

6

7

Time (Min)displacement devices. Optimal dispensing performance isdependent on storage conditions, equipment type, and set up.

Eutectic Au/Sn Solder Pastes
Metal Loading (3)Flux:

NC-SMQ 51 SC
NC-SMQ 51 A
NC-SMQ 75

Flux
Designation (1)

ROL1
R0L1
ORL0

Approximate
Residue (2)

47%
51%
41%

(1) Per J-STD-004 (2) as % of flux content

Printing

94%
94%
93.5%

Dispensing

92%
91%
90.5%

Used inHigh power LED; MEMS applications
Poor solderability surfaces in die and preform attach
No-clean applications needing low residue(3) Will vary with application

askus@indium.com

14

Flip-Chip Epoxy Fluxes
Introduction
Epoxy fluxes are designed for use in either Flip-Chip (direct
chip attach), chip-scale package (CSP) attach, or ball attach
applications. They are applied in applications where partial
encapsulation of the finished solder joint is desired, andcompatibility with a subsequent capillary underfill is needed.
They are therefore intended to be used alongside traditional
underfill materials, not as a replacement.
Epoxy fluxes provide two functions: a metal-cleaning flux andan adhesive.
• As fluxes, these materials promote good solderability bycleaning the adjacent metal surfaces.
• As adhesives, they cure after reflow, providing a thermoset
polymer layer surrounding the solder connections,providing protection against challenging environments(such as humid or corrosive atmospheres) and also
providing reinforcement against lifting of UBM or substratepads during physical or thermal stressing.
Since the epoxy fluxes are very similar in chemical nature to
the most commonly used epoxy underfills, excellent adhesion
is maintained between the cured epoxy flux and the underfill
material, eliminating issues with delamination.

Choosing an Epoxy Flux
Different customers choose different expoxy fluxes fordifferent reasons: some need a high Tg (glass transition
temperature), while others need excellent solderability.
Table 1 compares the physical properties of the materials
and also includes standard test data. Table 2 shows
a comparison of the solderability of a 30mil (0.76mm)
diameter SAC305 sphere on a copper coupon after passing
through a standard Pb-free reflow profile.

Key Performance Needs:• Stable thermoset residue• Compatible with standard underfill materials• Compatible with conformal coatings• Compatible with most finishes and coatings• Environmentally friendly• Fast curing

Table 2

Solderability Comparison
Time on230 ˚C
Hotplate

NC Spray
Flux

PK001

PK002

PK005

0 secs

68

54

55

59

20 secs

47

0

0

59

0

0

0

53

1800 secs

0 = little or no wetting/spreading
100 = sphere spreads out over substrate metallization

Table 1

Flip Chip Epoxy Flux Physical Properties
Test

PK-001

PK-002PK-005

MethodTg / ˚C

85

85

36

TMA (heating rate 10C/min)

CTE (<Tg) / ppm

65

56

52

TMA (heating rate 10C/min)

Viscosity / kcps

20-10050-25010-15

Brookfield (Model HB DV11-CP, 0.5rpm)

Typical Tack Strength140-250 grams

140-250 grams

70-150 grams

Tack Tester (Malcom TK-1)

Shelf-life (-40 ˚C)

6 months

6 months

6 months

Brookfield (Model HB DV11-CP, 0.5rpm)

Pot-life (25 ˚C)

8 hours

8 hours

10 hours

Brookfield (Model HB DV11-CP, 0.5rpm)

Quantitative Halide Content 0%0%0%

MIL-STD-883,5011.4

Extractable Ionic Content <20ppm<20ppm<20ppmMIL-STD-883E

Solid Content

100%

100%

80%

TGA

Flux Residue
Compatability

Compatible with
underfill

Compatible with
underfill

Compatible with
underfill

CSAM

Corrosivity

Pass

Pass

Pass

J-STD-004

SIR>1E8 (Pass)>1E8 (Pass)>1E8 (Pass)

J-STD-004

www.indium.com

15

Solder Preforms
Introduction
Solder Preforms deliver precise amounts of solder tospecific locations.
Solder Preforms come in standard shapes such as
squares, rectangles, washers and discs. Typical sizes
range from 0.010” (0.254mm) up to 2” (50.8mm). Smaller
and larger sizes, as well as custom shapes, are alsoavailable. Dimensions can be held to tight tolerances toassure volume accuracy.

Application Note: Selecting Alloys
Indium Corporation offers a wide assortment of alloys withliquidus temperatures that range from 47°C to 1063°C.
Alloys can be In–containing, Au-containing, Pb–Free,fusible, or standard Sn/Pb, as well as many others.
Alloy selection should be based on strength and otherrequired physical properties, as well as the preferredsoldering temperature and the operating temperature of
the device being soldered. A general rule is to select analloy that melts at least 50°C higher than the operationaltemperature of the part being soldered.
Next, consider the materials being soldered and whichsolder is most compatible with them. For example,
Sn–based solders will scavenge the gold from Au-platedparts, forming brittle intermetallics, so In-based solders
are generally recommended in these cases.
Metals and alloys have different characteristics that canaffect the ease with which they can be made into different
shapes and thicknesses. It is important to consider the
shape of the final preform in the alloy selection process.
The operating environment of the completed assembly isalso an important consideration for alloy selection. Will
it operate in very high or very low temperatures, or be
subjected to vibration? If so, you need to select an alloythat will stand up to these conditions.
Our Application Engineers work with you to determine thebest alloy for your application.

Application Note:
Selecting Dimensions
The location of the solder joint and the volume of solder
needed will determine the size and shape of the preform.
Once the flat dimensions (diameter, length, width) havebeen determined, the thickness can be adjusted to achieve
the desired volume of solder. Generally, for through–holeconnections, add 10–20% to the calculated barrel volume
for a good fillet. For pad to pad joints, figure about 5% lesssurface area than the pad.
Each Solder Preform should have a burr tolerance
specified. You should stay as close to standard tolerances
as possible to avoid adding cost and lead time to yourpreforms.
Indium Corporation has an extensive library of sizes andshapes from which you can choose, or we can create a
set–up specifically for your application. Using an existing
preform size can eliminate the additional time and costassociated with creating a new set–up.

Dimensional Specification
Width/Length or Diameter
Up to 0.100” (2.54mm)
Over 0.100” (2.54mm)
Thickness:
Up to 0.001” (0.025mm)
0.001” (0.025mm) to .002” (0.050mm)> 0.002” (0.050mm) to .010” (0.254mm)> 0.010” (0.254mm) to .020” (0.508mm)> 0.020” (0.508mm) to .050” (1.27mm)> 0.050” (1.27mm)
Burr Tolerances (Discs, Squares & Rectangles):≤ 0.050” (1.27mm)> 0.050” (1.27mm) to .500” (12.7mm)> 0.500” (12.7mm)
Burr Tolerances (Washers & Frames):≤ 0.100” (2.54mm)
When thickness ≥ 2/3 of I.D.

Typical Tolerances± 0.002”(± 0.051mm)± 0.005” (± 0.127mm)± 0.0002” (0.005mm)± 0.0003” (0.0076mm)± 0.0005” (0.0127mm)± 0.0010” (0.0254mm)± 0.0025” (0.0635mm)± 5%
0.002” (0.050mm)
0.003” (0.076mm)
0.005” (0.127mm)
0.003” (0.076mm)
0.005” (0.127mm)
askus@indium.com

16

Package-on-Package/
System-in-Package Materials
Introduction
Package-on-Package (PoP) and System-in-Package (SiP)
are an exciting new technology that allows standard
SMT assembly techniques to be used to manufacture
combinations of different integrated circuits. For example,
different types of memory may be used in combination toprovide both DRAM and Flash in the same package for use ina cell phone.
• PoP Fluxes are suitable for stacking CBGAs and small
PBGAs, which are not subject to flexing.
• PoP Pastes are useful when board flexing may occur
during reflow, such as larger PBGAs. The presence of asmall amount of metal powder allows complete reflowed
joints to form, even when the substrate twists and gaps
form between the solder sphere and the substrate.

Key Performance Needs:• Particle-, Crystal-, Bubble-Free• Homogeneous• Viscosity stable with time
• Pb-Free alloy compatible• Applied by dipping• Air reflow• Wetting onto a variety of metals• No-clean materials

PoP Flux Properties
Product Name

~ResidueFlux Designation (1)Reflow

PoP Flux 23LV

ROL1

~50%

Air

PoP Flux 30B

ROL0

~45%

Air

TACFlux® 483

ROL1

~48%

Air/Nitrogen

TACFlux 010

ROL0

~4%

Nitrogen®

(1) Per ANSI/IPC
TM650: J-STD-004

Application of PoP Flux
DIP

PLACE

Flux reservoir

www.indium.com

Doctor blade(keeps flux
surface planar)

REFLOW

17

PoP Interconnect Spacers
Introduction
Package-on-Package (PoP) Interconnect Spacers are
solder-clad preforms that utilize the strength, melting point,and conductivity of copper for stacking and spacing of
BGA packages. Once reflowed, PoP Interconnect Spacerstransfer signals through substrate layers, just as solder
spheres do.

Key Performance Needs:• Maintain standoff• Allow multiple reflow cycles anda higher package stack• Exhibit high thermal and electrical conductivity• Improve overall assembly strength

Alloys/Materials• Core material: OFHC copper• Annealed per ASTM-B152• Tensile strength: 35,000 psi max• Other coppers are available upon request
Solder cladding may be matched to the specified spherecomposition for uniformity of design.

Solder Cladding Alloys
The most commonly requested solder cladding alloys for
package assembly are listed below. Please contact us for otheravailable alloys.

Solder Cladding Alloys
Alloy
63.0Sn/37.0Pb
90.0Pb/10.0Sn
95.5Sn/3.8Ag/0.7Cu
96.5Sn/3Ag/0.5Cu
95.5Sn/4Ag/0.5Cu

Print Solder
Paste

Liquidus
Solidus183˚C Eutectic
302˚C
275˚C
220˚C
217˚C
220˚C
217˚C
220˚C
217˚C

MEMORY
Dispense
SolderPaste

Place
Spheres and
PoP Spacers

Packaging
PoP Interconnect Spacers are packaged using the best
method to handle the size and strength of the spacer.
Common packing methods include jars, boxes (stack packor layer pack) and tape & reel. Most packages can bebackfilled with argon upon request.
When possible, fill each package with the quantity ofspacers used in one shift.

LOGIC

Place andReflow

Reflow
Print Solder
Paste

Print Solder
Paste

PCB
Place andReflow

Place PoP
Spacers

Reflow

askus@indium.com

18

Technical Support
Indium’s Process Simulation Lab
provides Applications Engineers with the tools towork with you and industry partners on designed
experiments to fully characterize materials and theiruse in leading-edge technology applications, including:• Voiding analysis (x-ray and SAM) of die-attachmaterials, underfills, and solder joints• Reflow (up to 360˚C) in a variety of atmospheres• Dispense and spray applications development• Microphotography• Solder sphere and metal (alloy) analysis to PPM levels

Indium’s Process Simulation Lab Capabilities:• Stencil printing• Precision syringe
dispensing• Fully automated 3D
solder paste inspection• Component placement• Acoustic microscope
inspection• T emperature-humidity-bias
testing (SIR & ECM)
• Mechanicalstrength testing• F orced air convection andinfrared reflow• TG/DTA & DSC analysis• Wave soldering• Thermal cycling• X-Ray analysis• And more...

• Wetting Balance testing

Technical Support—When You Need It.
You have challenges, opportunities, and newprocesses to address. Indium’s technical expertiseis available in several forms:
Online Support:• Powerful, interactive, online technicalknowledgebase• http://knowledge.indium.com• Available 24/7
• Customer-rated answers
Phone and Email:• Personal service• Customized information• See semiconductor directorywww.indium.com

Training Workshops:• General or specific training• Your site or off-site• Customized to meet your needs
Site Visits:• Total focus on YOUR issues• Spotlight on your process

Confidentiality
Indium Corporation recognizes the importance ofconfidentiality in the design of solutions. As a trusted
partner, our engineers will work with you to help you
find the right solution for your assembly problems. We
can help you find the right alloy for performance andthe best solder form for ease of assembly.

19

Semiconductor Support Directory
Asia PacificnNorth America

Richard Brooks

Tel: +1 817 528 3697
Fax: +65 6268 5646
		

ASIA TECHNICAL MANAGER
rbrooks@indium.com
nYong-Kwang Chia
TECHNICAL MANAGER
ykchia@indium.com

n

Irene Leow
TECHNICAL MANAGER
ykchia@indium.com

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TECHNICAL SUPPORT ENGINEER
lkoorithodi@indium.comnnTel: +65 6268 8678
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Mobile: +65 9671 6469

DA

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Tel: +91 44 43552662
Fax: +91 44 43552662
Mobile: +91 99406 94038

Sehar Samiappan

Tel: +60 4587 1766
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Mobile: +60 12 483 9314

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n

Hu Di
Tel: +86 512 62834900
Senior Sales Engineer
dhu@indium.com			Gulf Guo
TECHNICAL MANAGER	
gguo@indium.com

n

n

SPM

Michael Qiu

DA

Tel: +86 (0)512 62834900 x8319
Fax: +86 (0)512 62834911
SPM
		
Tel: +86 512 62834900

Sales Engineer
mqiu@indium.com
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n

Martin Wen

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Christopher NashnMario ScalzonPaul SochanMichael Fenner
TECHNICAL PROJECTS MANAGER	
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Tel: +1 315 853 4900 x7521
TECHNICAL SUPPORT ENGINEER
Fax: +1 315 853 1000
MIDWEST U.S.
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TECHNICAL SUPPORT ENGINEER	
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mscalzo@indium.com			Tel: +44 1908 580401
Fax: +44 1908 580411

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n

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Amanda WhittemorenTel: +1 315 853 4900 x7599
Fax: +1 315 853 1000

Fax: +1 315 853 1000

DA*

Ronald C. Lasky, Ph.D., PE

Tel: +1 508 930 2242
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Fax: +1 508 533 5678
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Tel: +1 315 853 4900 x7613
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Tel: +1 315 853 4900 x7541
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Fax: +1 315 853 1000TECHNICAL SUPPORT, Metals & Chemicals
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VICE PRESIDENT TECHNOLOGY
nclee@indium.com

DA

Tel: +40 723 171 398
Fax: +40 256 491 008
		

Tel: +44 1908 580401
Applications Engineer
Fax: +44 1908 580411
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Karthik Vijayamadhavan Tel: +1 315 853 4900 x7519

MARKET MANAGER
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Tel: +44 1506 412087
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Fax: +44 1506 414857
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EuropeSPM *DA

TECHNICAL SUPPORT ENGINEER
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Southwest/Rocky Mountains U.S.
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Jim Hisert

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Tel: +86 (0)139 237 08051
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Manager Technical Services
Fax: +52 333 670 5106
Latin America
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Tel: +1 315 853 4900 x7594
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Fax: +1 315 853 1000
NORTHEAST U.S.
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Fax: +1 315 853 1000
SOUTHEAST U.S.
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Tel: +1 315 853 4900 x7531
Manager of Technical Services Fax: +1 315 853 1000
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Mobile: +60 12 416 5814

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Andy Mackie, Ph.D.

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Mobile: +65 9842 7593

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n

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Semiconductor Packaging
Materials
Die-Attach* Industry Expert

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Locations Worldwide
We develop, manufacture, andmarket soft solders, electronic
assembly and packaging materials,
indium alloys, and inorganic
compounds.

Corporate Structure
Clinton, NY USA

Milton Keynes, UK

Singapore• Solder Products Business Unit
• Metals and Chemicals
Business Unit

Our Goal
Increase our customers’
productivity and profits throughpremium design, application, andservice using advanced materials.
Chicago, IL USA

Utica, NY USA

Clinton, NY USA

Utica, NY USA

Suzhou, PRC

Shenzhen, PRC

Liuzhou, PRC

South Korea

Our basis for success:• Excellent productquality and performance• Technical andcustomer service• Cutting-edge material
research and development• Extensive product range• Lowest cost of ownership

Form No. 98377 (A4) R2

www.indium.com

askus@indium.com

ASIA:
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CHINA: Suzhou, Shenzhen, Liuzhou: +86 (0)512 628 34900
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