Bonding, Handling, and Mounting Procedures for

Millimeterwave PHEMT MMIC’s

M/A-COM Products

Rev. V4

Application Note

M570

2

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Die Down

Method

Resultant

Thermal

Resistance

Temperature

Required

High

Temperature

Capabilities

Power

Handling

Capability

Ease of

Operation

Special

Equipment

Required

Potential

Problems

Conductive

Epoxy

Good with

proper

technique

Room temp to

150˚C

Good

Low to

medium

power

Easiest to

apply

Little to none

High series or thermal

resistance

Soft solder i.e.,

Pb-Sn-Ag

(90,5,5)

Pb-Sn (60,40)

Good to very

good

200 - 280˚C

180 - 200˚C

Good

Good to very

good for low

or high

power

Simple

application

Heated stage

hot gas

bonder or gas

curtain and

furnace

Flux is usually required

with lead solders.

Cleaning of flux must

be done carefully

Eutectic Solder

Au-Sn (80,20)

Sn-Sb (97,3)

Very good

Approx. 300˚C

Approx. 230˚C

Good

Very good

Simple

application

Heated stage

or hot gas

bonder

Needs clean reducing

atmosphere

Die Bonding with Conductive

Epoxies - LNAs

Although satisfactory die down bonds may be obtained

using these epoxies, the power amplifiers may not per-

form to specification. The low noise amplifiers work well

when epoxies are used.

The following precautions

should be observed to obtain consistently strong bonds.

The low noise die are back metallized with Pd/Ni/Au

(100/ 1,000 / 30,000Å) metallization.

Thermally and

electrically conductive epoxy is recommended for die-

mounting the low noise die, although Au/Sn eutectic

preforms can be used.

Table 1. Selection Guide for Die Down Bonding Techniques

Figure 1. Die Bonding Criteria

The attachment surface should be clean and flat. Electri-

cally conductive epoxy is required and must be within the

warranty shelf and/or pot life. It is advisable to use half

the listed pot life. Silver conductive epoxies should not

be used where they will come into contact with lead tin

solders or high tin solder. There can be an anodic reac-

tion which may cause failure of the bond. Epotek H2OE

or Ablestick 84-1LMI is recommended.

A minimum amount of epoxy should be applied, then the

die should be placed into position. Figure 1 shows good

and unacceptable bonds.