Improving reliability for electronic power modules

Abstract

The current trend in power electronics, particularly for power module development is focused on improved reliabiliy, quality and energy efficiency. In applications such as in railways or heavy machinery, high power in the ranges of several hundred kilowatts to lower megawatts is required. Innovation in such areas are needed to improve the systems reliability as failures could be extremely costly to replace. In some cases they may involve loss of life. Most systems are expected to function constantly on daily cycles and may be subjected to harsh environments as well. Power module systems today seek to integrate more functions by implementing good electrical design principles. Such ideas can only be realized if the materials and processes used are reliable and robust. The main objective of this literature work is to understand the reliability problems and failures, as well as improvements which are being made on engineering material selection for power modules.

Bond graph multi-physics modeling of encapsulating materials in power electronic modules

“…Thus, the spring-damping mechanical cell is excited by a generalized flow source, corresponding to a strain ratė th (t) sharing the same effort as the cell [12], through a iso-effort 0 junction. Indeed, it is clear that the total strain of a mechanical cell is the sum of the strain related to the applied stress and the strain related to the thermal expansion (7). The relation between the strain rates is directly deduced (8).…”

“…However, their introduction in power electronic leads to an increase in thermo-mechanical stresses on the various components of the modules packaging (solder, substrate, encapsulant...). In this packaging, the encapsulating silicone gel constitutes a particularly sensitive component [6][7][8] to thermal, mechanical and dielectric stresses. It is subjected to specific failure modes [9] during the ageing of the power modules.…”