Air cooled heat exchanger for multi-chip assemblies

Abstract

An air-cooled self-contained evaporator and condenser apparatus with no external power source, the apparatus including a cold plate having a first surface with recesses formed therein in a matrix or array corresponding to the matrix or array of chips on a multi-chip module or unit. The opposite surface of the cold plate includes a finned arrangement which, in conjunction with the cold plate, forms part of an isolated evaporation chamber of the cooling unit, with the chamber housing a boilable fluid which changes phase from liquid to vapor. Positioned above and contiguous with the isolated chamber is a condensing chamber, including a plurality of tubular passageways, the external portions of which are finned for ready removal of heat. For attachment of the cold plate portion of the unit to the chips, suitable heat transfer slugs, such as aluminum nitride slugs, are affixed in the recesses, with opposites surfaces thereof bonded to the exposed faces of the chips. Heat is transferred from the chips through the slugs, through the cold plate to cause boiling of the fluid within the chamber, the vapors of which are condensed in the upper part of the cooling unit to thus return as fluid to the chamber.