IGBT Modules - Technologies, Driver and Application (Second Edition) - page 506

climatic conditions. The first count represents the temperature swings that occur during
the operation
shows an example of T
). The second count represents
the temperature differences of the lowest climatic temperature point to the highest
temperature value of the area examined. These are, as described, the junction
temperatures for the bond wire connections, and the system solder temperature for the
assessment of thequality of the solder connection baseplate toDCB.
The next step is, to transform or define the multitude of different temperature
fluctuations into a constant temperature difference
. This is then used for the test
cycle. The need for this conversion is based on the fact that the test equipment, which
performs the accelerated test, is not in a position to represent a wide range of different
temperatures. Instead, a fixed lower temperature T
and a fixed upper
temperature T
is set, between which the device is operated alternately. If a
temperature difference
had been set, then, bymeans of the above acceleration
models, a calculation can bemadeof the required test cycles.
Fig. 14.5
Example of the derivationof the required test cycles based on the temperature
swings during operation for a cycling test under the existing application requirements
(formulas for the life timemodel are referring t
how an example for the derivation of test cycles for a cycling
test, based on the concept o
ith the assumption of certain parameters under
which themodule is to be operated in the target application:
Overall lifetime of the application: 15 years
2 load cycles per day
Consideration for temperature fluctuations duringoperation
Consideration for temperature fluctuations between the lowest climatic
temperature and the highest temperature for each cycle
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