Simulating the Effect of Rigid Frameworks on the Mechanical Properties of Transient Liquid Phase Sintered (TLPS) Alloys

Abstract

Abstract The need for power electronic devices and materials that can operate in harsh environments, together with the Restriction of Hazardous Substances (RoHS) legislation, has driven industry and researchers to develop new attach materials. Transient Liquid Phase Sintered (TLPS) joints are strong candidates to replace the current die attach materials due to their superior mechanical, thermal, and electrical properties. Despite these qualities, current TLPS systems may exhibit stiff and brittle behavior that can lead to die or attach fracture under large thermomechanical strains during wide temperature range cycling, or under mechanical stress from shock and vibration loading, such as is experienced in automotive electronics. This paper presents an approach for reducing thermal and mechanical strain levels by incorporating Transmission Electron Microscopy (TEM) Cu grids as a reinforcement to the attach material. The grids serve as ductile reinforcement capable of absorbing elastic and plastic energy, and as a barrier for crack propagations through the relative brittle TLPS material. Homogenization calculations were used to evaluate the effective properties of the TLPS, followed by numerical analysis that shows the effect of the grids on the die attach structure, and the mechanical integrity of the design.