Implementation of a new thermal path within the structure of inorganic encapsulated power modules

Abstract

The demands on power modules regarding power density and reliability are continuously rising. Conventional encapsulation materials are limited in their thermal performance. In this study, a completely new material class is used within a power module. This new class is the group of inorganic materials, specifically ceramic encapsulation materials. The use of ceramic encapsulation materials generates new possibilities for optimizing the heat dissipation within power modules. In comparison to conventional encapsulation materials, ceramic composites can dissipate the semiconductor's heat loss much more efficient due to its enhanced thermal conductivity. This improves the transient thermal resistance of the module (Zth). Furthermore, an additional copper layer (TMC - Thermal mass circuit), which is connected to the heatsink below, is applied to the top of the encapsulation. This opens up a new thermal path in the module without changing its footprint or overall structure. In particular, the geometrically difficult area above the on-chip contacts can be used completely for cooling for the first time. Experiments show that the combination of a ceramic encapsulation and the TMC structure can reduce the semiconductor's temperature by more than 12 K. This enables a higher lifetime, efficiency and reliability of power modules with high energy density.