HMC903-Die Data Sheet
Rev. A | Page 10 of 13
MOUNTING AND BONDING TECHNIQUES FOR MILLIMETERWAVE GaAs MMICS
The HMC903-Die is attached directly to the ground plane
eutectically or with conductive epoxy (see the General Handling
section, the Mounting section, and the Wire Bonding section).
The 50 Ω microstrip transmission lines on 0.127 mm (5 mil)
thick alumina thin film substrates are recommended for
bringing RF to and from the HMC903-Die (see Figure 20).
When using 0.254 mm (10 mil) thick alumina thin film
substrates, the die is raised 0.150 mm (6 mil) so 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 heat spreader (moly tab),
which then attaches to the ground plane (see Figure 21).
RF GROUND PLANE
0.102mm (0.004") THICK GaAs MMIC
WIRE BOND
0.127mm (0.005") THICK ALUMINA
THIN FILM SUBSTRATE
0.076mm
(0.003")
14481-020
Figure 20. Routing RF Signal
RF GROUND PLANE
0.102mm (0.004") THICK GaAs MMIC
WIRE BOND
0.254mm (0.010") THICK ALUMINA
THIN FILM SUBSTRATE
0.150mm
(0.006") THICK
MOLY TAB
0.076mm
(0.003")
14481-021
Figure 21. Routing RF Signal with Moly Tab
Microstrip substrates are placed 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).
HANDLING PRECAUTIONS
Follow the precautions detailed in the following sections to
avoid permanent damage to the device.
Storage
All bare die are placed in either waffle or gel-based ESD protective
containers and then sealed in an ESD protective bag for shipment.
After opening the sealed ESD protective bag, store all die in a
dry nitrogen environment.
Cleanliness
Handle the chips in a clean environment. Do not attempt to
clean the chip using liquid cleaning systems.
Static Sensitivity
Follow ESD precautions to protect against ESD strikes.
Transients
Suppress instrument and bias supply transients while bias is
applied. Use the shielded signal and bias cables to minimize
inductive pickup.
General Handling
Handle the chip along the edges with a vacuum collet or with a
sharp pair of bent tweezers. The surface of the HMC903-Die
has fragile air bridges and must not be touched with the
vacuum collet, tweezers, or fingers.
Mounting
The HMC903-Die is back metallized and can be die mounted
with gold tin (AuSn) eutectic preforms or with electrically
conductive epoxy. The mounting surface must be clean and flat.
Eutectic Die Attach
An 80% gold/20% tin preform is recommended with a work
surface temperature of 255°C and a tool temperature of 265°C.
When hot 90% nitrogen/10% hydrogen gas is applied, the tool
tip temperature is 290°C. Do not expose the chip to a temperature
greater than 320°C for more than 20 sec. No more than 3 sec of
scrubbing is required for attachment.
Epoxy Die Attach
Apply a minimum amount of epoxy to the mounting surface so
that a thin epoxy fillet is observed around the perimeter of the
HMC903-Die after 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. These
bonds are thermosonically bonded with a force of 40 g to 60 g.
DC bonds of 0.001 in (0.025 mm) diameter, thermosonically
bonded, are recommended. Create ball bonds with a force of
40 g to 50 g and wedge bonds at 18 g to 22 g. Create bonds with
a nominal stage temperature of 150°C. A minimum amount of
ultrasonic energy is applied to achieve reliable bonds. All bonds
are as short as possible, less than 12 mil (0.31 mm).
