IGBT Modules - Technologies, Driver and Application (Second Edition) - page 519

Fig. 14.18
Result of a load change test (taken from
14.5.4Diffusion soldering for the chip solder layer
The principle of diffusion soldering has already been described in chapte
this process was first used in discrete components, it now finds its first application in
IGBT modules. The aim of diffusion soldering in new module developments is to
increase the maximum allowed junction temperature during actual operation from the
present 150°C to 175°C and higher; and thiswhile increasing the load cycle capability at
the same time.
Because the technical process is simple to implement even for high-volume
manufacturing, it is expected that diffusion soldering will become the standard for future
module developments.
14.5.5 Improved system solder layer
Because of the technical process limitation for high-volumemanufacturing, currently an
improved system solder process is under development, which is to increase the load
cycle capability, whilst using the samematerials. The focus of this improvement is given
to the individual soldering processes, and the composition of the solder paste for the
system solder layer. Modules with this improved system solder are already available as
shows the progress in the soldering process compared to a conventional
standard soldering process after a cycling test of 25000 cycles at a
= 130K. The
picture in
shows strong delamination of the system solder layer, which is
characterised by the light areas of theDCB. In contrast, thepicture i
only aminor delamination.
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