Insulated metal substrate for power modules using anodic oxide film of aluminum

To improve the insulation reliability of insulated metal substrates for power modules, we propose an insulated metal substrate that has a porous alumina anodic oxide film along the interface between an aluminum base and resin insulating layer. By having two anodic oxide films, i.e., inorganic and organic acids, compared with conventional substrates, the proposed substrate improves the adhesiveness with the resin insulating layer, resulting in 160% improvement in insulation resistance after 2400 h under atmospheric condition in which the temperature was 85°C and relative humidity was 85%, and 30% improvement in breakdown voltage compared with conventional substrates.