Numerical Approach to Cold Gas Spray on Ceramic Substrates for Power Electronics Packaging

Abstract

In power electronic, ceramic substrates are used owing to their high thermal conductivity and dielectric strength. These substrates cannot withstand high voltages in the range of 20kV because thickness limitations inherit from the direct bond copper manufacturing method. This manufacturing process uses high temperature in order to bond the material layers. This negatively affects the material’s reliability due to the differing materials thermal expansion coefficients and the resulting residual stress. All this results in hindering the ceramic substrate in obtaining a higher dielectric strength. In contrast, cold gas spray has the potential to provide higher reliability due to its bonding mechanism, which relies on plastic deformation of solid particles at very high strain rates during impact to create a mechanical bond, forming a thick deposit. However, cold gas spray on ceramics has not been widely studied due to their brittleness and their inability to form a metallic bond. This work is aimed at providing an effective processing parameter map of the cold gas spray process to achieve a thick copper deposit on aluminum nitride on the basis of the comparison of experimental results with a numerical model and finite element simulation formulated in Mathematica and ABAQUS, respectively.