7
Figure 14. Recommended die assembly
Assembly Techniques
The backside of the MMIC chip is RF ground. For mi-
crostrip applications the chip should be attached directly
to the ground plane (e.g. circuit carrier or heatsink) using
electrically conductive epoxy
[1,2]
. For conductive epoxy,
the amount should be just enough to provide a thin l-
let around the bottom perimeter of the die. The ground
plane should be free of any residue that may jeopardize
electrical or mechanical attachment. Caution should be
taken to not exceed the Absolute Maximum Rating for
assembly temperature and time.
Thermo-sonic wedge bonding is the preferred method
for wire attachment to the bond pads. The RF connec-
tions should be kept as short as possible to minimize
inductance. Gold mesh or double-bonding with 0.7mil
gold wire is recommended. Mesh can be attached using a
2mil round tracking tool and a too force of approximately
22grams with an ultrasonic power of roughly 55dB for a
duration of 76 8mS. A guided wedge at an ultrasonic
power level of 64dB can be used for the 0.7mil wire. The
recommended wire bonding stage temperature is 150
2C.
The chip is 100ìm thick and should be handled with
care.
This MMIC has exposed air bridges on the top surface.
Handle at the edges or with a custom collet (do not pick
up die with vacuum on die center).
This MMIC is also static sensitive and ESD handling pre-
cautions should be taken.
Notes:
1. Ablebond 84-1 LM1 silver epoxy is recommended.
2. Eutectic attach is not recommended and may jeopardize reliability
of the device.
IF1
IF2
LO
RF
Vgs
100pF
Note:
1. Flares on thin lm
substrate compensate
bonding wire inductance.
