Abstract: An electronic multichip module suitable for use in a hostile environment. The module includes a metallic base member and a metallic cover hermetically and metallically sealed to the base member, the base member and cover together forming an enclosure. Spaced metallic support members are located within the enclosure and a plurality of integrated circuit units are stacked, in sandwich fashion, between the support members. The integrated circuit units each include a metal plate extending between the support members and an integrated circuit chip mounted thereon in heat conductive relationship. The metal plate, the support members and the enclosure form a heat sink for the integrated circuit units and the enclosure provides a low cost hermetic seal for the entire assembly of integrated circuit units. Planar arrays of conductive elements may be utilized to interconnect the integrated circuit chip to the terminals of the integrated circuit units.