# IGBT Modules - Technologies, Driver and Application (Second Edition) - page 507

495
Outdoor temperature [°C] -25 -20 -15 -10 -5
0
5
10 15 20 25 30
Days per year
5
10 10 20 25 30 45 50 50 50 35 35
Load cycles per day
2
2
2
2
2
2
2
2
2
2
2
2
Load cycles per year
10 20 20 40 50 60 90 100 100 100 70 70
Load cycles in15 years
150 300 300 600 750 900 1350 1500 1500 1500 1050 1050
T
op,min,Diode
[°C]
-25 -20 -15 -10 -5
0
5
10 15 20 25 30
T
op,max,Diode
[°C]
126 126 126 126 126 126 126 126 126 126 126 126
T
op,Diode
[K]
151 146 141 136 131 126 121 116 111 106 101 96
n
Stress
293 521 462 814 893 936 1220 1170 1004 855 506 424
9097
Tab. 14.2
Example of the derivation of the required test cycles based on the
temperature swings, resulting from the climatic considerations, for a cycling test under
the existing application requirements
To what extent the climatic conditions need to be considered depends on the specific
application. Ingeneral, the climatic valuesmatter in all applications operatedoutdoors.
The necessary number of test cycles for this example is 21494, composed of the
respective results of the active and climatic calculation. In both calculations the same
acceleration parameters t
on,Stress
, I
Stress
,
T
Stress
andT
j,min,Stress
were used.
For the calculation of the required test cycles the following equations were used, based
on theCoffin-Mansonmodel:
1
op
Stress
load
test
T
T
n n
β
=
Eq. 14.10
4
3
op,
mean ,j
Stress ,
mean ,j
2
op
Stress
op,on
Stress ,on
K273
T
K 1285
K273
T
K 1285
op
Stress
load
test
I
I
t
t
e
e
T
T
n n
β
β
+
+
β
⋅ 
⋅ 
=
Eq. 14.11
escribes the relationship of test cycles to the number of load cycles as a
function of the respective temperature fluctuations
T
Stress
and
T
op
. This is valid when
examining the thermal cycling tests to investigate the system solder.
applies
to the power cycling test to investigate the bond wire connections. As influencing
parameters in addition to the temperature swings
T
Stress
and
T
op
also the following
additional factors are of importance:
Minimal temperatureT
j,min,op
andT
j,min,Stress
per cycle
Time t
on,op
and t
on,Stress
for the component per load cycle
Operating current I
op
and I
Stress
for the time t
on,op
and t
on,Stress
The numerical values
β
1
to
β
4
used i
an
generally vary from one
manufacturer to another and from product to product and they result from amultitude of
tests carried out. The correct or recommended values have to be requested from the
manufacturer before implementinga lifetime calculation.
1...,497,498,499,500,501,502,503,504,505,506 508,509,510,511,512,513,514,515,516,517,...548