Direct Metallization-Based DBC-Free Power Modules for Near-Junction Water Cooling: Analysis and Experimental Comparison

Reducing the thermal resistance is vital for power modules. Thermal conducting paths are formed by heterogeneous layers for insulation, causing inevitably high thermal resistance. In this article, with the aid of direct metallization technology, a direct bonded copper (DBC)-free power module concept is proposed to achieve near-junction water cooling. A 55% reduction of thermal resistance is achieved by using a DBC-free power module instead of a DBC interface. Reliability analysis indicates that the DBC-free power module is sufficiently reliable in terms of mechanical stress, fatigue, and peel strength. The junction temperature of the DBC-free power module is experimentally compared to indirectly and directly water-cooled power modules with the DBC interface. The proposed near-junction water cooling method has effectively achieved reductions of 28 °C and 11 °C in junction temperature, respectively, under full load conditions when compared to the designs of indirectly and directly water-cooled power modules. The maximum junction temperature rise Δ T j of the indirectly water-cooled power module is reduced from 50 °C to 21 °C. The unlimited promise of direct metallization technology in 3-D packaging is also highlighted.