Hitachi IGBT Module Application Manual
7
7.1
Reliability
Module Failure Regions
Figure 58 shows the generalized failure rate behavior of Hitachi IGBT modules. Historically, such a
"bathtub-shaped" curve is sectioned into three regions, namely:
A:
B:
C:
Infant mortality
Premature failure
End-of-life failure
Figure 58. Module Failure Regions
7.2
Failure Factors
Table 11 categorizes IGBT module failure factors and includes examples for each failure category.
Table 11. Failure Mechanisms
Failure Factor
Materials and structures of
parts
Deviation in Product Process
Examples
1) Chemical interactions among metals or with die
2) Mismatching of thermal expansion rate
1) Failure of Al wire bonding
2) Scar of die surface pattern
3) Failure of air-tight packaging
4) Failure of solder
1) Destruction due to thermal expansion
2) Die destruction due to exceeding isolation voltage
1) Package destruction due to exceeding isolation
voltage
2) Die destruction due to exceeding isolation voltage
1) Connection bending
2) Package cracking
Corrosion of outer electrode
Rusting of terminals
Change in device electrical characteristics due to
accumulation of surface electric charge
Thermal Stress
Electrical stress
Mechanical Stress
Chemical Stress
Radiation
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