Copper Like Thermal Conductivity and Silicon Like Coefficient of Thermal Expansion Copper Graphene for High Power IGBT by Metal Injection Molding

Abstract

Enhanced stability, lifetime and safety of high power IGBT (Insulated Gate Bipolar Transistor) modules are a result of their progressive material selection, thereby necessitating the invention of new composite materials. High-end power modules are operated close to the maximum physical matching capability of their layered materials, leading to decreased lifetime and degraded performance, and thus creating demand for new composite materials with higher thermal conductivity and lower coefficient of thermal expansion (CTE). To eliminate failures caused by the CTE mismatch (∼300%) between metal and substrate material interface, we report for the first time Cu/Gr–Cu composite which exhibits similar thermal conductivity to pure copper (390 W/(m·K)), much higher than the range of metal injection molded copper heat sink (320–340 W/(m·K)), while featuring low silicon-like CTE (∼5 ppm/K). This is realized by injection parameter manipulation to not only reduce voids (vacancies) but increase the interface bonding through the use of electrodeposited copper on graphene (i.e., Gr–Cu). Such excellent property locates the Cu/Gr–Cu in the top of the Ashby map and shows excellent temperature stability with lower thermal distortion parameter (TDP). Thus, this excellent composite material is the only material simultaneously with high thermal conductivity and low CTE, making it uniquely suited for high power module applications, especially for hybrid and electric vehicles.