Section 5 Maintenance - ESAB ESP-50 Instruction Manual

sectIon 5
5.4 IGbt handling & replacement
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 contact-
ing the gate and emmiter sense pins.
always ground parts touching gate pins during installation. In general, stan-
dard esd precautlions 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.
• Use soldering irons with grounded tips when soldering to gate terminals.
When mounting IGBT 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 4-3. Also,
care must be taken to achieve maximum contact (i.e. minimum contact thermal
resistance) for the best heat dissipation.
Application of a thermal pad on the contact surface improves it thermal conductiv-
ity. See Replacement Parts section for the required pad.
A torque wrench should be used. Tighten mounting screws to 28 in-lbs
(3.2 m-n); wire connecting screws to 19 in-lbs (2.1 m-n). If torque is too heavy, the
device can damage like the above "one-sided tightening".
Two-Point Mounting Type
Temporary tightening-


Final tightening- 


Figure 5-2. screw Fastening order
Four-Point Mounting Type
Temporary tightening - 
Final tightening- 


228
maIntenance
  
  
  
  


