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.

The die-attach layer is one of the most critical elements for high-temperature power electronics applications. The increase in operating temperature requires new materials with higher melting points and suitable thermo-mechanical properties. Among the possible solutions, sintering of Ag pastes (nanoparticles, nanoflakes and particles near the nanosize range) is an interesting method, because it requires moderate (<300°C) processing temperatures. These lower processing temperatures are suitable for implementation in mass manufacturing and the equipment for doing so are readily available. The aim of this write-up is to detail the qualification efforts being done on the Ag sinter solutions, in particular on copper (Cu) surfaces. The literature work will cover reliability and manufacturing concerns which are of primary interest to the general engineering community. These concerns must be addressed from several view points; design, processability and equipment. The outlook for implementation of this technology is bright and is in-line with the lead free initiative being addressed by the RoHS and WEEE directives for power devices.

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