MITSUBISHI RF POWER MODULE
ELECTROSTATIC SENSITIVE DEVICE
OBSERVE HANDLING PRECAUTIONS
RA30H4452M
PRECAUTIONS, RECOMMENDATIONS and APPLICATION INFORMATION:
Construction:
This module consists of an alumina substrate soldered on a copper flange. For mechanical protection a plastic cap
is attached. The MOSFET transistor chips are die bonded onto metal, wire bonded to the substrate and coated by
resin. Lines on the substrate (eventually inductors), chip capacitors and resistors form the bias and matching circuits.
Wire leads soldered onto the alumina substrate provide DC and RF connection.
Following conditions shall be avoided:
a) Bending forces on the alumina substrate (for example during srewing or by fast thermal changes)
b) Mechanical stress on the wire leads (for example by first soldering then screwing or by thermal expansion)
c) Defluxing solvents reacting with the resin coating the MOSFET chips (for example Trichlorethylene)
d) Frequent on/off switching causing thermal expansion of the resin
e) ESD, surge, overvoltage in combination with load VSWR, oscillation, etc.
ESD:
This MOSFET module is sensitive to ESD voltages down to 1000V. Appropriate ESD precautions are required.
Mounting:
The heat sink flatness shall be less than 50µm (not flat heat sink or particles between module and heat sink may
cause the ceramic substrate in the module to crack by bending forces, either immediately when screwing or later
when thermal expansion forces are added).
Thermal compound between module and heat sink is recommended for low thermal contact resistance and to
reduce the bending stress on the ceramic substrate caused by temperature difference to the heat sink.
The module shall first be screwed to the heat sink, after this the leads can be soldered to the PCB.
M3 screws are recommended with tightening torque 0.4 to 0.6Nm.
Soldering and Defluxing:
This module is designed for manual soldering.
The leads shall be soldered after the module is screwed onto the heat sink.
The soldering temperature shall be lower than 260°C for maximum 10 seconds, or lower than 350°C for maximum 3
seconds.
Ethyl Alcohol is recommend to remove flux. Trichlorethylene type solvents must not be used (they may cause
bubbles in the coating of the transistor chips, which can lift off bond wires).
Thermal Design of the Heat Sink:
At Pout=30W, VDD=12.5V and Pin=50mW each stage transistor operating conditions are:
Pin
(W)
Pout
(W)
Rth(ch-case)
(°C/W)
IDD @ hT=40%
VDD
(V)
Stage
(A)
1st
2nd
3rd
0.05
1.5
1.5
9.0
5.0
2.4
1.2
0.30
1.50
4.20
12.5
9.0
30.0
The channel temperatures of each stage transistor Tch = Tcase + (VDD x IDD - Pout + Pin) x Rth(ch-case) are:
Tch1 = Tcase + (12.5V x 0.30A - 1.5W + 0.05W) x 5.0°C/W = Tcase + 11.5 °C
Tch2 = Tcase + (12.5V x 1.50A - 9.0W + 1.50W) x 2.4°C/W = Tcase + 27.0 °C
Tch3 = Tcase + (12.5V x 4.20A - 30.0W + 9.0W) x 1.2°C/W = Tcase + 37.8 °C
For long term reliability the module case temperature Tcase is better kept below 90°C. For an ambient temperature
Tair=60°C and Pout=30W the required thermal resistance Rth (case-air) = ( Tcase - Tair) / ( (Pout / hT ) - Pout + Pin ) of the heat
sink, including the contact resistance, is:
Rth(case-air) = (90°C - 60°C) / (30W/40% – 30W + 0.05W) = 0.67 °C/W
When mounting the module with the thermal resistance of 0.67 °C/W, the channel temperature of each stage
transistor is:
Tch1 = Tair + 41.5 °C
Tch2 = Tair + 57.0 °C
Tch3 = Tair + 67.8 °C
175°C maximum rating for the channel temperature ensures application under derated conditions.
RA30H4452M
2 Dec 2002
MITSUBISHI ELECTRIC
7/9
MITSUBISHI [ Mitsubishi Group ]
