Advances and challenges of experimental reliability investigations for lifetime modelling of sintered silver based interconnections

The cost and the package size driven size reduction of semiconductors lead to much higher heat generation. Also the use of new high power technologies on the basis of SiC produces is a need for high conductivity of the interconnect materials. Therefore the requirements for mechanical, thermal and electrical properties of interconnect materials increase compared to existing eutectic solder and glue materials. One of the promising solutions is a sintered layer between semiconductor and substrate. Especially from sintered layers one expects very high thermal conductivity and good mechanical properties in the package. Therefore, new materials with advanced behavior exploiting nano-effects have been developed in the last years. However, processes to use such materials as TIM-material for power applications are still to be optimized for e.g. zero pressure processing. So also their failure mechanisms, to be identified in lifetime investigations, are yet unknown as well as their stability. In order to enable prolonged function of these interfaces, thermo-mechanical reliability has to be assured. Dedicated fatigue tests have to be conducted to evaluate lifetime under relevant testing conditions, then failure mechanisms such as delamination or cracking have to be identified, understood and quantitatively condensed into a lifetime model to predict reliability for future designs. Within this paper, we present a guideline for the mechanical acceleration of reliability experiments for end-of-lifetime prognostics as well as the state of the art regarding reliability and mechanical characterization of sintered silver.