Investigations on the high temperature suitability of diffusion soldered interconnects

In this study it was found that the HotPowCon-soldered (HPC) interconnections show another kind of ageing effects than comparable assemblies with soldered or silver-sintered joining zones. The formation of vertical cracks can observed but could not be attributed solely to the decrease in volume due to the conversion of remaining solder within the joining zone into intermetallic phases (IMC). Rather, these result from the different coefficients of thermal expansion of the selected joining partners and the joining materials themselves. The occurrence of mechanical stress within the joining zone in combination with the stiff and brittle properties of the IMP promotes the formation of the vertical cracks. In contrast to the ageing effects of soldered or silver-sintered interconnections, the HPC-soldered structures hardly impair their electrical and thermal function.