HMC930A Datasheet, PDF (15/16 Pages) Analog Devices – Test instrumentation

Data Sheet
MOUNTING AND BONDING TECHNIQUES FOR
MILLIMETERWAVE GaAs MMICS
Attach the die directly to the ground plane eutectically or with
conductive epoxy (see the Handling Precautions section, the
Mounting section, and the Wire Bonding section).
Microstrip, 50 Ω, transmission lines on 0.127 mm (5 mil) thick
alumina, thin film substrates are recommended for bringing the
radio frequency to and from the chip (see Figure 38). When
using 0.254 mm (10 mil) thick alumina thin film substrates,
raise the die 0.150 mm (6 mils) to ensure that the surface of the
die is coplanar with the surface of the substrate. One way to
accomplish this is to attach the 0.102 mm (4 mil) thick die to a
0.150 mm (6 mil) thick, molybdenum (Mo) heat spreader (moly
tab), which is then attached to the ground plane (see Figure 38).
0.102mm (0.004") THICK GaAs MMIC
0.076mm
(0.003")
WIRE BOND
RF GROUND PLANE
0.127mm (0.005") THICK ALUMINA
THIN FILM SUBSTRATE
Figure 38. Die Without the Moly Tab
0.102mm (0.004") THICK GaAs MMIC
0.076mm
(0.003")
WIRE BOND
RF GROUND PLANE
0.150mm (0.005") THICK
MOLY TAB
0.254mm (0.010") THICK ALUMINA
THIN FILM SUBSTRATE
Figure 39. Die With the Moly Tab
Place microstrip substrates as close to the die as possible to
minimize bond wire length. Typical die to substrate spacing is
0.076 mm to 0.152 mm (3 mil to 6 mil).
HMC930A
Handling Precautions
To avoid permanent damage, follow these storage, cleanliness,
static sensitivity, transient, and general handling precautions:
 Place all bare die in either waffle or gel-based ESD
protective containers and then seal the die in an ESD
protective bag for shipment. Once the sealed ESD
protective bag is opened, store all die in a dry nitrogen
environment.
 Handle the chips in a clean environment. Do not attempt
to clean the chip using liquid cleaning systems.
 Follow ESD precautions to protect against ESD strikes.
 While bias is applied, suppress instrument and bias supply
transients. Use shielded signal and bias cables to minimize
inductive pick up.
 Handle the chip along the edges with a vacuum collet or
with a sharp pair of bent tweezers. The surface of the chip
may have fragile air bridges and must not be touched with
vacuum collet, tweezers, or fingers.
Mounting
The chip is back metallized and can be die mounted with AuSn
eutectic preforms or with electrically conductive epoxy. Ensure
that the mounting surface is clean and flat.
When attaching eutectic die, an 80/20 gold tin preform is
recommended with a work surface temperature of 255°C and a
tool temperature of 265°C. When hot 90/10 nitrogen/hydrogen
gas is applied, ensure that tool tip temperature is 290°C. Do not
expose the chip to a temperature greater than 320°C for more
than 20 seconds. For attachment, no more than 3 seconds of
scrubbing is required.
When attaching epoxy die, apply a minimum amount of epoxy
to the mounting surface so that a thin epoxy fillet is observed
around the perimeter of the chip once it is placed into position.
Cure epoxy per the schedule of the manufacturer.
Wire Bonding
RF bonds made with two 1 mil wires are recommended. Ensure
that these bonds are thermosonically bonded with a force of
40 grams to 60 grams. DC bonds of a 0.001” (0.025 mm)
diameter, thermosonically bonded, are recommended. Make
ball bonds with a force of 40 grams to 50 grams and wedge
bonds with a force of 18 grams to 22 grams. Make all bonds
with a nominal stage temperature of 150°C. Apply a minimum
amount of ultrasonic energy to achieve reliable bonds. Make all
bonds as short as possible, less than 12 mils (0.31 mm).
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