Thermal and Reliability Performance Comparison of DBC-Based and Organic-Based Double-Sided Cooled Power Modules

Abstract

Direct Bonded Copper (DBC) is the most popular solution for conventional high-power modules because of superior thermal/electrical/mechanical performance and mature manufacturing. To meet the rising demand of power density and power rating, a Double-Sided Cooled (DSC) sandwich structure using dual insulated metal-clad substrates was proposed and DBC still dominated the substrate selection of DSC power modules. However, there are several long-existing reliability challenges of conventional DBC-based power modules and the cost of DBC is relatively high compared with organic and metal (e.g. lead frame) substrates. This study proposes a DSC 1.2 kV half-bridge power module using dual epoxy-resin Insulated Metal Substrate (eIMS) for solving DBC-based power module issues and providing a cost-effective solution. The thermal performance outperforms traditional Alumina (Al2O3) DBC-based DSC power module due to moderate thermal conductivity (10 W/mK) and thin (120 μm) epoxy-resin composite dielectric layer compared with Alumina. The breakdown voltage of this high thermally conductive organic dielectric is 5 kVAC (@ 120 μm) and the Glass Transition Temperature (Tg) is 300°C which is indispensable for Wide-Band-Gap (WBG) devices and high-power applications. In terms of thermal-mechanical reliability, the organic-based DSC power module can pass the thermal cycling test over 2000 cycles by optimizing the mechanical properties of the encapsulant material. In conclusion, this paper not only proposes a competitive organic-based power module but also a methodology of evaluation for thermal and mechanical performance.