MICROWAVE CORPORATION

5 - 100

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5

Mounting & Bonding Techniques for Millimeterwave GaAs MMICs

The die should be attached directly to the ground plane eutectically or with conductive epoxy (see HMC general Han-

dling, Mounting, Bonding Note).

50 Ohm Microstrip transmission lines on 0.127mm (5 mil) thick alumina thin film substrates are recommended for bring-

ing 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 ribbon bond length. Typical

die-to-substrate spacing is 0.076mm (3 mils). Gold ribbon of 0.075 mm (3 mil) width and minimal length <0.31 mm (<12

mils) is recommended to minimize inductance on RF, LO & IF ports.

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.

Assembly Diagram

3 mil Ribbon Bond

3 mil Ribbon Bond

3 mil Ribbon Bond

3 mil Ribbon Bond

HMC337

GaAs MMIC SUB-HARMONICALLY

PUMPED MIXER, 17 - 25 GHz

v01.0803