Parametric Study of Damage Evolution in Silver Sintered Layers of Double Sided Power Electronics Modules of Electric Vehicles

Abstract:
Double sided modules accommodating wide band gap (WBG) devices are increasingly used in electric vehicles owing to their lower thermal resistance and parasitic inductances. Compared with single sided modules having a single ceramic substrate, the mechanical constraint applied on the silver sintered bonding layers in double sided modules (with two ceramic substrates) poses a more challenging reliability issue. In this work, we develop a parametric model to investigate the effects of layout, geometry and material properties on damage distribution in silver sintered layers of double sided modules. Anand viscoplastic model was used to describe the inelastic deformation of sintered silver under power cycling. Equivalent inelastic strain accumulated in each power cycle was used as the damage parameter and failure criterion. The model enables parametric study of damage distribution in double sided modules, and help improve design for maximum reliability. Using this model, the effects of parameters such as spacer and die thicknesses were investigated in this study.