GaAs MMIC SUB-HARMONICALLY
PUMPED MIXER, 28 - 40 GHz
MMIC Assembly Techniques for HMC259
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 rec-
ommended 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).
Figure 3: Typical HMC259 Assembly
Microstrip substrates should 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).
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