MICROWAVE CORPORATION

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MIC Assembly Techniques

Mounting & Bonding Techiniques for Millimeterwave GaAs MMICs

The die should be attached directly to the ground plane eutectically or with conductive epoxy (see HMC general Handling, Mounting,

Bonding Note).

50 Ohm Microstrip transmission lines on 0.127mm (5 mil) thick alumina thin film

substrates are recommended for bringing RF to and from the chip (Figure 1). If

0.254mm (10 mil) thick alumina thin film substrates must be used, the die should

be raised 0.150mm (6 mils) so that the surface of the die is coplanar with the

surface of the substrate. One way to accomplish this is to attach the 0.102mm

(4 mil) thick die to a 0.150mm (6 mil) thick molybdenum heat spreader (moly-tab)

which is then attached to the ground plane (Figure 2).

Microstrip substrates should be brought as close to the die as possible in order

to minimize bond wire length. Typical die-to-substrate spacing is 0.076mm (3

mils).

An RF bypass capacitor should be used on the Vdd input. A 100 pF single layer

capacitor (mounted eutectically or by conductive epoxy) placed no further than

0.762mm (30 mils) from the chip is recommended. The photo in figure 3 shows a

typical assembly for the HMC265 MMIC chip.

HMC265

v01.0701

GaAs MMIC SUB-HARMONICALLY

PUMPED DOWNCONVERTER, 20 - 32 GHz

Figure 3: Typical HMC265 Assembly