A package for a semiconductor device or circuit comprises a semiconductor switch module having a metallic base on an exterior side and metallic pads. A sealed metallic enclosure holds the semiconductor switch module. The metallic enclosure has a set of dielectric regions with embedded or pass-through electrical terminals that are electrically insulated or isolated from the sealed metallic enclosure. The electrical terminals are electrically connected to the metallic pads. A housing is adapted for housing the semiconductor switch module within the metallic enclosure. The housing comprises chamber for holding or circulating a coolant overlying the metallic base.