Abstract: A dual-board host or main printed wiring structure of a circuit module with increased component mounting area is made plug-compatible with a backplane to which single-board host or main boards may be attached with connectors of differing dimensions and pin configurations, the center line of which are offset from each other. The connection sides of the two boards are respectively bonded to a heat sink frame structure having a thickness which corresponds to the connector offset on the backplane such that the total thickness of one of the printed wiring boards, the heat sink frame and the two bonding layers with respect to board to center line distances equals the connector offset on a given backplane. Direct connections to both boards of the dual-board structure can thus be made from the backplane to reduce connection length and reliability relating to a mezzanine board mounted on a single-board host.