Heat Exchanger for Electronic Assemblies

Abstract

A liquid-cooled heat exchanger for electronic assemblies and a method of making the heat exchanger. The exchanger has a solid metal body in the form of an elongated flat plate to which the electronic assembly can be mounted, or a number of such plates formed in an L- or U-shaped configuration to enclose two or more sides of the assembly. The elongated body is formed by extrusion, with parallel enclosed longitudinal passages formed along a length of the body during the extrusion process. Transverse passages are drilled to intersect the extruded longitudinal passages. The longitudinal passages and transverse passages are plugged on at least one of their outside ends, and optionally at points along their lengths, to create desired patterns of liquid flow through the heat exchanger.

1 . A heat exchanger for electronic assemblies, comprising:
 a) a solid heat-conductive base plate having a length, a width and a thickness, the plate being formed by extrusion with a plurality of parallel longitudinal passages enclosed in the thickness along the length of the base plate; the base plate also having a plurality of parallel transverse passages drilled across at least part of the width, perpendicular to the plurality of longitudinal passages, such that each transverse passage intersects at least two longitudinal passages;   b) a fluid inlet at an end of a longitudinal passage or a transverse passage;   c) a fluid outlet at an end of a longitudinal passage or a transverse passage; and   d) a plurality of plugs for blocking fluid flow, inserted into the plurality of longitudinal passages and the plurality of transverse passages,   the plugs being located such that fluid is constrained to flow from the fluid inlet through the plurality of longitudinal passages and the plurality of transverse passages to the fluid outlet.   
     
     
         2 . The heat exchanger of  claim 1 , in which the exchanger further comprises a solid heat-conductive side wall having a length, a height and a thickness, formed by extrusion with the base plate to form an L-shaped unit, the side wall having a plurality of parallel longitudinal passages enclosed in the thickness along the length of the side wall; the side wall also having a plurality of parallel transverse passages drilled across at least part of the height, perpendicular to the plurality of longitudinal passages, such that each transverse passage intersects at least two longitudinal passages. 
     
     
         3 . The heat exchanger of  claim 2 , in which at least one of the transverse passages is drilled to intersect at least one longitudinal passage on the base plate and at least one longitudinal passage on the side wall. 
     
     
         4 . The heat exchanger of  claim 1 , in which the exchanger further comprises two solid heat-conductive side walls having a length, a height and a thickness, formed by extrusion with the base plate to form a U-shaped unit, at least one of the side walls having a plurality of parallel longitudinal passages enclosed in the thickness along the length of the side walls; and at least one of the side walls also having a plurality of parallel transverse passages drilled across at least part of the height, perpendicular to the plurality of longitudinal passages, such that each transverse passage intersects at least two longitudinal passages. 
     
     
         5 . The heat exchanger of  claim 4 , in which at least one of the transverse passages in a side wall is drilled to intersect at least one longitudinal passage on the base plate and at least one longitudinal passage on the side wall. 
     
     
         6 . The heat exchanger of  claim 4 , in which both side walls are extruded with longitudinal passages and drilled with transverse passages. 
     
     
         7 . The heat exchanger of  claim 1 , in which the plugs are made of resilient material. 
     
     
         8 . The heat exchanger of  claim 1 , in which at least an end portion of the transverse passages and the longitudinal passages is threaded. 
     
     
         9 . The heat exchanger of  claim 8 , in which at least some of the plugs are threaded to mate with a threaded end portion of the longitudinal passages and the transverse passages. 
     
     
         10 . The heat exchanger of  claim 1 , in which at least one plug has a length sufficient to block more than one passage when the plug is inserted into an intersecting passage. 
     
     
         11 . The heat exchanger of  claim 1 , further comprising a U-shaped connector for insertion into an end of two parallel longitudinal passages or two transverse passages, for fluid flow therebetween. 
     
     
         12 . A method of making a heat exchanger for electronic assemblies, comprising:
 a) extruding a solid heat-conductive plate having a length, a width and a thickness, with a plurality of parallel longitudinal passages enclosed in the thickness along the length of the plate;   b) drilling a plurality of parallel transverse passages drilled across at least part of the width, perpendicular to the plurality of longitudinal passages, such that each transverse passage intersects at least two longitudinal passages;   c) inserting a plurality of plugs for blocking fluid flow into the plurality of longitudinal passages and the plurality of transverse passages, the plugs being located such that fluid is constrained to flow from a fluid inlet at an end of a longitudinal passage or a transverse passage through the plurality of longitudinal passages and the plurality of transverse passages to a fluid outlet at an end of a longitudinal passage or a transverse passage.   
     
     
         13 . The method of  claim 12 , further comprising sealing an open end of at least one longitudinal passage or transverse passage. 
     
     
         14 . The method of  claim 12 , further comprising installing a connector at the fluid input and at the fluid output. 
     
     
         15 . The method of  claim 12 , further comprising mounting an electronic assembly to the base plate. 
     
     
         16 . The method of  claim 12 , further comprising cutting the base plate to a determined length. 
     
     
         17 . The method of  claim 12 , in which the plate is formed with a base plate and a side wall forming an L-shaped heat exchanger. 
     
     
         18 . The method of  claim 12 , in which the plate is formed with a base plate and two side walls forming a U-shaped heat exchanger.