IGBT Modules - Technologies, Driver and Application (Second Edition) - page 512

Fig. 14.7
Coefficients of thermal expansion for variousmaterials used in IGBTmodules
as an example, shows the result of aTC test for a standard IGBTmodulewith
copper baseplate and Al
ceramics. Clearly visible in this test are the zones of
delamination of the solder layer. These zones always start from the corners of the DCB
andwill spread further from there
The thermal resistance in the area of the delaminated zones is much higher than the
original value. If a power semiconductor is positioned in this area, the increased thermal
resistance leads to an increase in junction temperatureT
Fig. 14.8
Example of delamination of the solder between the baseplate and the DCB
(system solder) in four X-ray pictures.
TC curves for selected material combinations and/or specific module packages are
published by the manufacturers of IGBT modules to serve the user as a basis for the
lifetime calculation.
shows an example of this. The module has a copper
baseplate. The test conditionsare as follows:
Minimum baseplate temperatureT
= 25°C
Typical cycle time t
= t
+ t
Heatingof themoduleby internal non-pulsed energisation
External cooling
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