Hitachi IGBT Module Application Manual
6
6.1
Handling
Mounting IGBT modules to Heat Sinks
6.1.1 Clamping Torque
Table 6. Clamping Torque
No
Screw
Rated
Torque
(N-m)
1.96
2.94
Recommended
Torque
(N-m)
1.67
2.45
Pre-clamping Torque
(N-m)
0.33 to 0.55
0.49 to 0.8
Final clamping
Torque (N-m)
1.67
2.45
1
2
M5
M6
6.1.2 Thermal Compound Grease
Apply thermal compound grease between the IGBT module and heat sink as explained below.
(1) First apply grease on the base side of module. Do this by roller/ brush or placing of
grease of uniform quantity at several points (see Figure 53). Table 7 shows the
recommended grease and its specific gravity. The recommended thickness of grease
should be in the range of 100
µ
m to 150
µ
m. For example, the quantity of grease
required (q) can be estimated using Equation 45.
Equation 45:
q
= s
!
t
!
k
Definitions:
S ( cm
2
)
t ( cm )
k ( kg/cm
3
)
Base area of module
Thickness of grease
Specific gravity of grease
For the case of three (3) points applying method, each point quantity should be 1/3 of the total
quantity of grease required. For the case of five (5) points, should be 1/5 of the total quantity of grease
required.
(2) Next, push the base side of the IGBT module against the heat sink, particularly since
such grease has a tendency to spread to all surfaces.
(3) Mount the IGBT module according to the clamping order of screw shown in Figure
preclude clamping beyond the maximum specified torque.
Note:
It is not necessary to allow for any rest time between pre-clamping
and final clamping activities.
49