Characterization of Alternative Sinter Materials for Power Electronics

Silver Sintering for die attach has gained increasing interest in past years. Compared to known interconnect materials such as Adhesives and Solder, the unique superior thermal and electrical properties of sintered silver joints enable power electronics to operate at greater reliability and at higher temperature. Copper, touted as the alternative, possess similar properties to silver and being the same material as metalized substrate can reduce CTE mis-match. Up till now copper sintering attracts great interest as an alternative optionfor die attach material. This study investigates the influence of using copper as the non-silver additives for formation of silver sintered layers as well as the effects on material properties of the sintered joints for die attach applications. The different sinter materials are evaluated by tensile strength, Young's modulus, die shear strength and electrical conductivity. Process-oriented test specimen were used to replicate the die attach layer formed during pressure sintering. This contribution demonstrates that the mechanical and electrical properties of the sintered layer are affected by non-silver particles. It was found that the used filler materials can lead to a decrease of mechanical and electrical properties in comparison to the pure silver interconnection. It was also found, that the copper paste obtained a relatively strong bonding and confirms thefeasibility as an alternative die attach material.