Mud-Cracking Effect of Sintered Silver Layer on Quantifying Heat Transfer Behavior of SiC Devices Under Power Cycling: Voronoi Tessellation Model

Mud-cracking of the sintered silver (Ag) layer of the SiC power module is commonly found during power cycling tests. In this article, the effect of the mud-cracking of sintered Ag on the heat transfer behaviors of SiC power module is studied based on a Voronoi tessellation model. This model is verified to be reasonable on the prediction of the equivalent thermal conductivity of sintered Ag as well as the thermal resistance of power module. The effect of the crack ratio on the equivalent thermal conductivity of sintered Ag is studied and an empirical model is proposed to predict the equivalent thermal conductivity of sintered Ag containing different mud-cracking ratios. The effect of mud-cracking ratio, chip size, sintered Ag thickness, and porosity on the thermal resistance of power module are studied. An equivalent model to study the heat transfer behaviors of the power module with mud-cracking is also developed to improve the calculation efficiency. This article establishes a new method to quantitively study the heat transfer behaviors of the power module under power cycling condition.