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.

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