Environmentally secure and thermally efficient heat sink assembly

Abstract

A heat sink is disclosed for cooling a module having a plurality of chip sites thereon. The heat sink includes a frame member which is made of a material having a coefficient of thermal expansion which is substantially that of the substrate to which it is bonded. The frame has a plurality of fins disposed around the perimeter and a support surface disposed inside the perimeter fins. An insert member made of a high thermal conductivity material rests on the support surface. The insert member has a plurality of fins disposed on one side thereof and a plurality of projections on the other side. Forced air flowing around the fins provides a mechanism for rapidly removing heat therefrom. Each of the projections is disposed above a chip site and extends almost into contact with the upper surface of a chip mounted on the module substrate. A thermal paste is used to transfer heat directly from the chip to the insert member hence a mechanism is provided for rapidly removing heat developed in each chip of the module. The insert member is bonded to the frame member with an appropriate environmentally secure bond to assure that the atmosphere within the module remains the same over the planned life of the product. The spacing between the projections advantageously provides a path for engineering wiring and component changes to be added to the module should such changes become necessary.