Combination of experimental and simulation methods for analysis of sintered Ag joints for high temperature applications

In order to get better a understanding of the reliability and thermo-mechanical behavior of pressure sintered Ag joints, especially at high temperatures, tensile test samples made of sintered Ag, have been designed and manufactured. The samples have been used for analyzing the temperature dependency of the stress-strain behavior as well as temperature and load depending creep properties of pressure sintered Ag. As a reference bulk Ag was tested. Mechanical properties like Young's modulus, yield strength, tensile strength or fracture strain of sintered Ag significantly show temperature dependency. For instance, the higher the temperature the lower is the yield strength. The strength and fracture strain of bulk Ag show temperature dependency as well. However, the mechanical properties of sintered and bulk Ag differ significantly which can be explained by their different microstructure. Furthermore, the analyses could prove that sintered Ag creeps but much less than Sn-based solder at the same temperature and level of stress. By fitting the experimental results parameters for the Garofalo creep law were obtained. These results were applied by means of FE-analysis. Furthermore, comparative experiments of thermal cycling test were conducted. As test sample a typical microelectronic assembly was considered, having a die Ag sintered on a lead frame.