A circuit module is provided in which at least one secondary substrate and preferably two such secondary substrates are populated with integrated circuits (ICs). A rigid core substrate for the circuit module is comprised of a structural member and a connective member. In a preferred embodiment, the structural member is comprised of thermally conductive material while the connective member is comprised of conventional PWB material. The secondary substrate(s) are connected to the connective member with a variety of techniques and materials while, in a preferred embodiment, the connective member exhibits, in a preferred embodiment, traditional module contacts which provide an edge connector capability to allow the module to supplant traditional DIMMs.