IGBT Modules - Technologies, Driver and Application (Second Edition) - page 379

DCB. One of these substances is for example hydrogen sulphide H
S. The hydrogen
sulphide leads to corrosion of the copper layer andmay cause both open and also short
circuits. This is activated by the forming of crystals which can bridge the gap between
two conductors.
Fig. 10.13
DCB subjected to hydrogen sulphide
Environmental influences may, however, already affect the outside of the module.
Demonstrated here is the contamination with saline air. It affects the terminals of the
module and leads to corrosion. This in itself is not critical in the beginning, provided the
contact resistance of the supply feed, the PCB or the DC-bus to the module is not
increased. Of course, the corrosionmust not proceed to a stage at which amechanical
failure occurs
shows anexample of a salt vapour test.
Fig. 10.14
Saltmist (vapour) test
10.4 Transport and storage
During transport and storage of IGBTmodulesmechanical stresses due to vibration and
shock are to be minimised just as environmental influences. Generally the storage of
modules under the maximum permissible values given in the datasheet is possible but
not recommended. Two years are generally specified as a maximum storage time.
During this time the following storage conditions should not be exceeded (as described
in the standard IEC 60721-3-1 for class 1K2):
Minimum air temperatureT
= 5
Maximum air temperatureT
= 40
Minimum relativehumidity
= 5%
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