Abstract: Clamp means for securing a printed circuit board to a chassis or "cold wall" with improved heat transfer characteristics. The chassis, which acts as a heat sink, is provided with elongated slots which receive the opposite edges of a heat conductive metallic plate sandwiched between insulating printed circuit layers of the printed circuit card. Disposed within each slot is an elongated clamp which, when set, not only forces the heat conductive plate into contact with a first wall of the elongated slot but also exerts a force against, and is in abutting relationship with, a wall normal to the first wall. This maximizes the cross-sectional area of the path through which heat can flow from the heat conductive metallic plate to the chassis, thus improving the heat transfer characteristics.