Electrical-thermo-mechanical Simulation for aluminum wire bonds in SiC Schottky diode packages

Abstract

Compared to traditional silicon based semiconductors, wide band gap semiconductors (e.g. GaN and SiC) have been widely used in high power electronics with their advantages of higher thermal conductivity, higher breakdown field strength, higher operating temperature and lower power loss. The SiC power diode packages, including Schottky Barrier Diode (SBD) and Junction Barrier Schottky (JBS), are usually manufactured with the SiC die as a function chip and aluminum wires as interconnections. Since aluminum wires are usually operated under the condition of high temperature and high power cycling, their fatigue damage is considered as one of great failures happened in package level. Because of the mismatch of coefficient of thermal expansions (CTEs) between the interconnections, aluminum wires are highly stressed under a multiple electrical-thermo-mechanical condition. This paper assesses the reliability of wire bonds in a SiC SBD package under an accelerated operation test condition with higher currents. And the fatigue damage of the wire bond was predicted by using a multi-physics finite element (FE) simulation method. In details, the strain-based and stress-based 3D finite element simulation models, which will be afforded to the traditional strain-based Coffin-Manson model and stress-based Basquin's equation for fatigue life prediction, were chosen to simulate the stress/strain density distribution of the wire bond in the SiC SBD package. Finally, the effects of the high current conditions on the the stress/strain density distribution of the wire bond were analyzed based on the simulation results.