Igbt Handling; Module Replacement - ESAB Powercut 900 Instruction Manual

SECTION 5
5.3

IgBT Handling

Since IGBT gates are insulated from any other conducting region, care should be taken to prevent static build up, which
could possibly damage gate oxides. All IGBT modules are shipped from the factory with conductive foam contacting the
gate and emitter sense pins.
Always ground parts touching gate pins during installation. In general, standard ESD precautions application to FETs should
be followed.
Other handling precautions that should also be observed are as follows:
• Use grounded work station with grounded floors and grounded wrist straps when handling devices.
• Use a 100Ω resistor in series with the gate when performing curve tracer tests.
• Never install devices into systems with power connected to the system.
5.4

Module replacement

When mounting modules on a heatsink, certain precautions should be taken to prevent any damage against a sudden
torque. If a sudden torque ("one-sided tightening") is applied at only one mounting terminal the ceramic insulation plate
or silicon chip inside the module may get damaged.
The mounting screws are to be fastened in the order shown in Figure 5-1. Also, care must be taken to achieve maximum
contact (i.e. minimum contact thermal resistance) for the best heat dissipation.
A torque wrench should be used. Tighten mounting and terminal screws per Torque Requirements shown in Subsection 7.3.
If device is over-torqued, the device can be damaged like the above "one-sided tightening".
Application of a Thermal Compound or Thermal Pad on the contact surface is required to properly remove heat from the
device. It is recommended that a unit manufactured with thermal compound use thermal compound for replacement, even
if replacement module was shipped with a thermal pad. Thermal compound may always be used as a replacement for a
pad. Never use both compound and a pad.
Thoroughly remove any residual material from the mating surfaces. Use Dow-340 Heat Sink Compound or equivalent. Apply
a thin layer (.005" nominal) between mating surfaces. If a thermal pad is used, ensure there are no folds or creases.

Two-Point Mounting Type
Initial tightening  
Final tightening  





figure 5-1 Screw fastening Order
61
MAINTENANCE
Four-Point Mounting Type
Initial tightening  

Final tightening  


  
  
  
  
