Memory Module Assembly Including Heat Sink Attached To Integrated Circuits By Adhesive And Clips

Abstract

A memory module assembly includes two-plate heat sink attached to one or more of the integrated circuits (e.g., memory devices) of a memory module PCBA by adhesive. The adhesive is either heat-activated or heat-cured. The adhesive is applied to either the memory devices or the heat-sink plates, and then compressed between the heat-sink plates and memory module using a fixture. The fixture is then passed through an oven to activate/cure the adhesive. The two heat sink plates are then secured by a clip to form a rigid frame.

1 . A method for manufacturing a memory module assembly comprising:
 forming a memory module printed circuit board assembly (PCBA) including:
 a substrate having opposing first and second surfaces, a plurality of wiring traces formed on the first and second surfaces, at least some of the wiring traces being connected to metal contact pads formed along a connector edge of the substrate, and 
 a plurality of first integrated circuit (IC) devices mounted on the first surface of the substrate such that an upper surface of each of the plurality of first IC devices faces away from the first surface of the substrate; 
   applying an adhesive to one of a planar first underside surface of a first heat-sink plate and the upper surface of at least one of said plurality of first IC devices;   mounting the first heat-sink plate and memory module PCBA into a fixture such that the planar first underside surface of the first heat-sink plate is pressed against the at least one of said plurality of first IC devices with the adhesive pressed therebetween, and a first outer surface of the first heat-sink plate that is opposed to the first underside surface contacts a first portion of the fixture;   heating the fixture at a first temperature for a period of time such that the adhesive undergoes at least one of activation and curing; and   cooling the fixture to a second temperature that is lower than the first temperature.   
   
   
       2 . The method according to  claim 1 , wherein mounting the first heat-sink plate and the memory module PCBA in the fixture further comprises:
 aligning and mounting the first heat-sink plate onto the memory module PCBA; and   placing the first heat-sink plate and the memory module PCBA into a recess formed in the fixture, and manipulating a spring clamp such that the first heat-sink is pressed against the associated IC device.   
   
   
       3 . The method according to  claim 1 , wherein applying the adhesive further comprises applying to the planar underside surface of the first heat-sink plate at least one of a thermal-bond adhesive film and a thermal conductive film. 
   
   
       4 . The method according to  claim 1 , wherein applying the adhesive further comprises applying to the upper surface of said at least one of the plurality of first IC devices one of a thermal-bond adhesive film and a thermal conductive film. 
   
   
       5 . The method according to  claim 1 , wherein heating the fixture comprises placing the fixture in an oven maintained at a temperature of at least 80° C. for approximately 15 minutes. 
   
   
       6 . The method according to  claim 1 ,
 wherein forming the memory module PCBA further comprises mounting a plurality of second IC devices on the second surface of the substrate such that an upper surface of each of the plurality of second IC devices faces away from the substrate;   wherein applying adhesive further comprises applying said adhesive to one of a planar second underside surface of a second heat-sink plate and the upper surface of at least one of said plurality of second IC devices;   wherein said mounting further comprises mounting said second heat-sink plate into said fixture such that the planar second underside surface of the second heat-sink plate is pressed against at least one of said plurality of second IC devices with the adhesive pressed therebetween, and a second outer surface of the second heat-sink plate that is opposed to second underside surface contacts a second portion of the fixture.   
   
   
       7 . The method according to  claim 6 ,
 wherein forming the memory module PCBA further comprises:
 mounting a first plurality of said first integrated circuit (IC) devices and a second plurality of said first IC devices on the first surface of the substrate such that upper surfaces of the first and second pluralities of first IC devices define a first plane that is parallel to the first surface of the substrate, 
 mounting a third IC device on the first surface between the first and second pluralities of first devices, the third IC device having an upper surface defining a second plane that is parallel to the first surface of the substrate, wherein the first plane is located between the second plane and the first surface of the substrate; 
   wherein the first heat-sink plate includes a first recessed region defined by a first upper surface region and an opposing first planar underside surface region, a second recessed region having a second upper surface region and an opposing second planar underside surface region, and a raised pocket structure defining a third upper surface region and an opposing third planar underside surface region, and the pocket region is disposed between the first and second recessed regions, and   wherein said mounting comprises mounting said first heat-sink plate such that a first recessed region is secured to at least one of said first plurality of said first IC devices, a second recessed region is secured to at least one of said second plurality of said first IC devices, and a raised pocket structure disposed between the first and second recessed regions is disposed over the third IC device.   
   
   
       8 . The method according to  claim 7 ,
 wherein mounting the plurality of first IC devices comprises mounting dynamic random access memory (DRAM) devices,   wherein mounting the third IC device comprises mounting an advanced memory buffer (AMB) device that is connected to each of the first and second pluralities of first IC devices by way of a bus disposed on said substrate.   
   
   
       9 . The method according to  claim 6 ,
 wherein at least one side edge of the substrate defines a positioning notch, and   wherein said mounting further comprises positioning said first and second heat-sink plates such that side wall structures disposed on each of said first and second heat-sink plates abutting a corresponding one of said first and second surfaces adjacent to said at least one side edge, and such that a tab disposed on at least one of the first and second heat-sink plates extends from a corresponding one of said side wall structures into the positioning notch.   
   
   
       10 . The method according to  claim 9 ,
 wherein the first heat-sink plate comprises said tab, and   wherein said mounting further comprises positioning said second heat sink plate such that a groove formed on said second heat sink plate receives an end of the tab.   
   
   
       11 . The method according to  claim 9 , wherein said mounting further comprises positioning said first and second heat-sink plates such that first and second tab portions respectively disposed on the first and second heat-sink plates extend partially into the notch. 
   
   
       12 . The method according to  claim 6 ,
 wherein said mounting comprises connecting at least one clip to said first and second heat-sink plates such that a first engaging portion of said at least one clip is connected to the first outer surface of the first heat-sink plate,   wherein said at least one clip includes a second engaging portion of said at least one clip is connected to the second outer surface of the second heat-sink plate, wherein said at least one clip includes a linking member connected between the first and second engaging members.   
   
   
       13 . The method according to  claim 12 , wherein connecting said at least one clip to said first and second heat-sink plates comprises connecting a first portion of said at least one clip to at least one first hook protruding from said first outer surface of said first heat-sink plate, and connecting a second portion of said at least one clip to at least one second hook protruding from said second outer surface of said second heat-sink plate. 
   
   
       14 . The method according to  claim 12 , wherein connecting said at least one clip to said first and second heat-sink plates comprises inserting a first protruding end structure of said at least one clip into at least one first slot defined on said first outer surface of said first heat-sink plate, and inserting a second protruding end structure of said at least one clip into at least one second slot defined on said second outer surface of said second heat-sink plate. 
   
   
       15 . The method according to  claim 12 , wherein connecting said at least one clip to said first and second heat-sink plates comprises:
 connecting a first single-piece clip between the first upper surface region and the second outer surface; and   connecting a second single-piece clip between the second upper surface region and the second outer surface.   
   
   
       16 . The method according to  claim 6 , wherein applying the adhesive further comprises applying a heat-activated adhesive material exhibiting a first, relatively low adherence when heated to a first, relatively high temperature, and exhibiting a second, relatively high adherence when subsequently cooled to a second, relatively low temperature. 
   
   
       17 . The method according to  claim 6 , wherein applying the adhesive further comprises applying one of a high thermal conductive adhesive film and a thermal-bond adhesive film. 
   
   
       18 . The method according to  claim 7 , wherein applying the adhesive comprises applying to said plurality of first IC devices one of a high thermal conductive adhesive film and a thermal-bond adhesive film, and disposing a thermal paste between said third IC device and said raised pocket structure. 
   
   
       19 . A method for manufacturing a memory module assembly comprising:
 forming a memory module printed circuit board assembly (PCBA) including:
 a substrate having opposing first and second surfaces, a plurality of first wiring traces formed on at least one of the first and second surfaces, each of the first wiring traces being connected to an associated metal contact pad formed along a connector edge of the substrate, the substrate also having opposing first and second side edges disposed at opposing ends of the connector edge, wherein each of said first and second side edges defines a notch; and 
 a first plurality of first integrated circuit (IC) devices and a second plurality of said first IC devices disposed on the first surface of the substrate such that upper surfaces of the first and second pluralities of first IC devices define a first plane that is parallel to the first surface of the substrate, and 
 a second IC device disposed on the first surface between the first and second pluralities of first devices, the second IC device having an upper surface defining a second plane that is parallel to the first surface of the substrate, wherein the first plane is located between the second plane and the first surface of the substrate; 
   applying an adhesive to one of first and second planar underside surfaces of a first heat sink plate and the upper surface of at least one of said first and second pluralities of said first IC devices, wherein the first heat-sink plate includes a first recessed region having a first planar upper surface and said first planar underside surface, disposed opposite to the first planar upper surface, a second recessed region having a second planar upper surface and said second planar underside surface disposed opposite to the second planar upper surface, and a raised pocket region defining a third planar upper surface and an opposing third planar underside surface, the pocket region being disposed between the first and second recessed regions,   mounting the first heat-sink plate and memory module PCBA into a fixture such that the planar first underside surface is pressed against the first plurality of first IC devices with the adhesive pressed therebetween, the planar second underside surface is pressed against the second plurality of first IC devices with the adhesive pressed therebetween, and the pocket region is disposed over the second IC device, and such that the first planar upper surface and the second planar upper surface contact a first portion of the fixture; and   heating the fixture at a first temperature for a period of time such that the adhesive undergoes at least one of activation and curing.   
   
   
       20 . The method according to  claim 19 ,
 wherein at least one side edge of the substrate defines a positioning notch, and   wherein said mounting further comprises positioning said first heat-sink plate such that a side wall structure disposed on said first heat-sink plate abuts said first surfaces adjacent to said at least one side edge, and such that a tab disposed on the first heat-sink plate extends from said side wall structure into the positioning notch.   
   
   
       21 . The method according to  claim 19 , wherein applying the adhesive comprises applying to said plurality of first IC devices one of a high thermal conductive adhesive film and a thermal-bond adhesive film, and disposing a thermal paste between said second IC device and said raised pocket structure.