Abstract:
A method of manufacturing a finned heat sink included obtaining a fin core, wherein the fin core is constructed of a conductive structural graphite-epoxy material. A fin cover is secured to the fin core using one of heat and pressure to define a heat sink fin, wherein the fin cover is constructed of a foil material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. patent application Ser. No. 10/161,792 filed Jun. 4, 2002, now U.S. Pat. No. 6,918,438, the contents of which are incorporated by reference herein in their entirety. 

   FIELD OF THE INVENTION 
   The present invention relates generally to a heat sink and more particularly to a finned heat sink having copper-clad graphite foils. 
   BACKGROUND OF THE INVENTION 
   As an electronic component operates, the electron flow within the component generates heat. If this heat is not removed, or dissipated, the electronic component may not operate correctly and may become damaged. Typically, the heat generated by the electronic component is dissipated by a cooling means, such as an aluminum (Al) or copper (Cu) heat sink which absorbs and dissipates the heat via direct air convection. These conventional heat sinks are well known in the electronics industry and are used extensively to dissipate heat generated by electronic components used in computers and various other electronic equipment. 
   Moreover, improvements in integrated circuit (IC) design and fabrication techniques are allowing IC manufacturers to produce smaller IC devices and other electronic components which operate at increasingly faster speeds and which perform an increasingly higher number of operations. As the operating speed and operational parameters of an electronic component increases, so too does the heat generated by these components. As a result, conventional aluminum (Al) and/or copper (Cu) heat sink designs gave way to current state-of-the-art graphite-epoxy finned heat sink designs, thus allowing for a faster and larger heat dissipation capability. 
   However, these graphite-epoxy finned heat sink designs have two main disadvantages. The first disadvantage is that current finned heat sink designs are mechanically fragile, thus allowing graphite-epoxy material to be ejected from the heat sink resulting in the contamination of neighboring electronic hardware with graphite-epoxy debris. Current methods to combat this problem include electroplating the finished heat sink assembly with electroless nickel. However, because electroless nickel is mechanically highly stressed, the nickel plating may easily peel. In addition, corrosion may occur due to plating solution becoming trapped within the crevices of the heat sink. Moreover, electroless nickel plating is expensive, adding to the already expensive manufacturing process. 
   The second disadvantage is that the graphite-epoxy composite is difficult to join to metals using conventional soldering operations, thus resulting in an increase in manufacturing/production cost and complexity. 
   SUMMARY OF THE INVENTION 
   A finned heat sink comprising: a plurality of heat sink fins, wherein each of the plurality of heat sink fins includes a fin cover and a fin core, wherein the fin core is constructed of a conductive structural graphite-epoxy material and wherein the fin cover is constructed of a foil material and is disposed relative to the fin core so as to envelope the fin core and a heat sink base, wherein the heat sink base is disposed so as to be in thermal communication with the plurality of heat sink fins. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the exemplary drawings wherein like elements are numbered alike in the several Figures: 
       FIG. 1  is a sectional side view of a graphite-epoxy finned heat sink, in accordance with a first embodiment; 
       FIG. 2  is a sectional side view of a graphite-epoxy finned heat sink, in accordance with a second embodiment; 
       FIG. 3  is a sectional side view of a graphite-epoxy finned heat sink, in accordance with a third embodiment; and 
       FIG. 4  is a sectional side view of a graphite-epoxy finned heat sink, in accordance with a fourth embodiment; 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a finned heat sink  100  in accordance with a first embodiment is shown and discussed. Finned heat sink  100  includes a heat sink base  102  and a plurality of heat sink fins  104 . Heat sink fins  104  include a fin core  106  and a fin cover  108 , wherein fin cover  108  includes a fin cover face  109  and wherein fin cover  108  is non-movably associated with fin core  106 . In addition, fin cover  108  is thermally communicated with fin core  106  so as to allow for a maximum amount of heat transfer. Fin core  106  includes a core top  110 , a core bottom  112  and has a core length  114 . Fin cover  108  includes a cover top  116 , a cover bottom  118  and a cover length  120 , wherein cover length  120  is preferably larger than core length  114 . Fin cover  108  is disposed relative to fin core  106  such that fin cover face  109  is adjacent to fin core  106  and such that cover bottom  118  is adjacent to core bottom  112  and cover top  116  extends beyond core top  110 . Cover top  116  is sealed so as to enclose core top  110  within fin cover  108 . 
   Heat sink base  102  includes a plurality of fin spacers  122  having a spacer core  124  and a spacer cover  126 , wherein spacer cover  126  is non-movably associated with spacer core  124 . In addition, spacer cover  126  is thermally communicated with spacer core  124  so as to allow for a maximum amount of heat transfer. Spacer core  124  includes a spacer core top  128 , a spacer core bottom  130  and a spacer core length  132 . Spacer cover  126  includes a spacer cover top  134 , a spacer cover bottom  136  and a spacer cover length  138 , wherein spacer cover length  138  is preferably larger than spacer core length  132 . Spacer cover  126  is disposed relative to spacer core  124  such that spacer cover bottom  136  is adjacent to spacer core bottom  130  and spacer cover top  134  extends beyond spacer core top  128 . Spacer cover top  134  is sealed so as to enclose spacer core top  128  within spacer cover  126 . 
   Finned heat sink  100  includes a plurality of internal heat sink fins  140  and a plurality of external heat sink fins  142  and is formed by positioning internal heat sink fins  140  between external heat sink fins  142  in a sandwich fashion such that external heat sink fins  142  are disposed on the outer most portion of finned heat sink  100 . External heat sink fins  142  are disposed so as to be parallel to internal heat sink fins  140  such that core top  110  of each heat sink fin  104  is adjacent to the core top  110  of the neighboring heat sink fin  104 . Fin spacers  122  are non-movably disposed between heat sink fins  104  in a sandwich fashion so as to separate heat sink fins  104  from each other such that core bottom  112  is adjacent to spacer core bottom  130 . In addition, heat sink fins  104  are preferably thermally communicated with fin spacers  122  so as to allow efficient thermal transfer between heat sink fins  104  and fin spacers  122 . 
   Heat sink base  102  also includes a base bottom  144  having a bottom material layer  146  constructed of a thermally conductive material, wherein bottom material layer  146  is disposed so as to seal cover bottom  118  to core bottom  112  and spacer cover bottom  136  to spacer core bottom  130 . 
   Fin core  106  is preferably constructed of a conductive structural graphite-epoxy material and is advantageously contained within fin cover  108  so as to prevent the contamination of neighboring hardware with graphite-epoxy debris. This is because cover top  116  is sealed so as to enclose core top  110  within fin cover  108  and cover bottom  118  is sealed by bottom material layer  146  so as to enclose core bottom  112  within fin cover  108 . In addition, this advantageously allows fin core  106  to be contained with fin cover  108  without the problems associated with electroless nickel plating. 
   Although heat sink fins  104  and fin spacers  122  are preferably non-movably associated using a thermally conductive soldering material  148 , heat sink fins  104  and fin spacers  122  may be non-movably associated using any method and/or device suitable to the desired end purpose. In addition, bottom material layer  146  may be non-movably associated with base bottom  144  via any method and/or device suitable to the desired end purpose, such as electroplating, physical vapor deposition and/or sputtering. 
   Although fin cover  108  is preferably constructed of 0.375 oz copper foil as known in the circuit board industry, fin cover  108  may be constructed of any material suitable to the desired end purpose. In addition, although fin cover  108  is preferably solid a foil material, fin cover  108  may also be a screened foil material. Moreover, although cover top  116  and spacer cover top  134  are preferably sealed via soldering and/or crimping, cover top  116  and spacer cover top  134  may be sealed using any method and/or device suitable to the desired end purpose. Moreover, fin cover  108  may be processed to promote material adhesion via any method or device suitable to the desired end purpose such as roughening. 
   In accordance with a first embodiment, fin cover  108  includes a copper-oxide treatment on fin cover face  109 . This copper-oxide treatment advantageously promotes the adhesion of fin cover face  109  to fin core  106 . Fin cover face  109  may be bonded to graphite-epoxy material of fin core  106  by compressing fin cover face  109  against fin core  106  while the graphite-epoxy material of fin core  106  is heated to a temperature range in which the graphite-epoxy material is pliable. This advantageously allows an epoxy-copper bond to form between fin cover face  109  and fin core  106 , wherein the epoxy-copper bond may withstand large temperature gradients such as those experienced in soldering operations. Although, fin cover  108  is preferably bonded to fin core  106  via a copper-oxide treatment, fin cover  108  may be bonded to fin core  106  using any adhesion promoting material, device or method suitable to the desired end purpose, such as Silane-based adhesion. 
   Referring to  FIG. 2 , a finned heat sink  200  in accordance with a second embodiment is shown and discussed. Finned heat sink  200  includes a heat sink base  202  and a plurality of heat sink fins  204 . Heat sink fins  204  include a fin core  206  and a fin cover  208 , wherein fin cover  208  is non-movably associated with fin core  206 . In addition, fin cover  208  is thermally communicated with fin core  206  so as to allow for a maximum amount of heat transfer. Fin core  206  includes a core top  210 , a core bottom  212  and has a core length  214 . Fin cover  208  includes a cover top  216 , a cover bottom  218  and a cover length  220 , wherein cover length  220  is preferably larger than core length  214 . Fin cover  208  is disposed relative to fin core  206  such that cover top  216  extends beyond core top  210  and cover bottom  218  extends beyond core bottom  212 . Cover top  216  and cover bottom  218  are sealed so as to enclose core top  210  and core bottom  212  within fin cover  208 . 
   Heat sink base  202  is preferably constructed of a thermally conductive metallic material and includes a base top  220  having a plurality of fin slots  222 . Heat sink base  202  may be constructed of any thermally conductive material suitable to the desired end purpose such as a refractory ceramic (Aluminum-Oxide, Boron-Nitride, Silicon-Carbide). Plurality of heat sink fins  204  are non-movably associated with plurality of fin slots  222  such that heat sink fins  204  are thermally communicated with heat sink base  202  so as to allow efficient thermal transfer between heat sink fins  204  and heat sink base  202 . Finned heat sink  200  is formed by non-movably associating one heat sink fin  204  with one fin slot  222  until all of the plurality of fin slots  222  contain a heat sink fin  204 . 
   Although heat sink fins  204  are preferably non-movably associated with fin slots  222  using a thermally conductive soldering material  224 , heat sink fins  204  may be non-movably associated with fin slots  222  using any method and/or device suitable to the desired end purpose. Moreover, although cover top  216  and cover bottom  218  are preferably sealed via soldering and/or crimping, cover top  216  and cover bottom  218  may be sealed using any method and/or device suitable to the desired end purpose. 
   Although fin cover  208  is preferably constructed of 0.375 oz copper foil as known in the circuit board industry, fin cover  208  may be constructed of any material suitable to the desired end purpose. In addition, although fin cover  208  is preferably a solid foil material, fin cover  208  may also be a screened foil material. Moreover, fin cover  208  may be processed to promote material adhesion via any method or device suitable to the desired end purpose such as roughening. 
   In accordance with a second embodiment, fin cover  208  includes a copper-oxide treatment on fin cover face  209 . This copper-oxide treatment advantageously promotes the adhesion of fin cover face  209  to fin core  206 . Fin cover face  209  may be bonded to graphite-epoxy material of fin core  206  by compressing fin cover face  209  against fin core  206  while the graphite-epoxy material of fin core  206  is heated to a temperature range in which the graphite-epoxy material is pliable. This advantageously allows an epoxy-copper bond to form between fin cover face  209  and fin core  206 , wherein the epoxy-copper bond may withstand large temperature gradients such as those experienced in soldering operations. Although, fin cover  208  is preferably bonded to fin core  206  via a copper-oxide treatment, fin cover  208  may be bonded to fin core  206  using any adhesion promoting material, device or method suitable to the desired end purpose, such as Silane-based adhesion. 
   Referring to  FIG. 3 , a finned heat sink  300  in accordance with a third embodiment is shown and discussed. Finned heat sink  300  includes a heat sink base  302  and a plurality of heat sink fins  304 . Heat sink fins  304  include a fin core  306  and a fin cover  308 , wherein fin cover  308  is non-movably associated with fin core  306 . In addition, fin cover  308  is thermally communicated with fin core  306  so as to allow for a maximum amount of heat transfer. Fin core  306  includes a core top  310 , a core bottom  312  and has a core length  314 . Fin cover  308  includes a cover top  316 , a cover bottom  318  and a cover length  320 , wherein cover length  320  is preferably larger than core length  314 . Fin cover  308  is disposed relative to fin core  306  such that cover bottom  318  is adjacent to core bottom  312  and cover top  316  extends beyond core top  310 . 
   Heat sink base  302  includes a plurality of fin spacers  322  having a spacer core  324  and a spacer cover  326 , wherein spacer cover  326  is non-movably associated with spacer core  324 . In addition, spacer cover  326  is thermally communicated with spacer core  324  so as to allow for a maximum amount of heat transfer. Spacer core  324  includes a spacer core top  328 , a spacer core bottom  330  and a spacer core length  332 . Spacer cover  326  includes a spacer cover top  334 , a spacer cover bottom  336  and a spacer cover length  338 , wherein spacer cover length  338  is preferably larger than spacer core length  332 . Spacer cover  326  is disposed relative to spacer core  324  such that spacer cover bottom  336  is adjacent to spacer core bottom  330  and spacer cover top  334  extends beyond spacer core top  328 . 
   Finned heat sink  300  includes a plurality of internal heat sink fins  340  and a plurality of external heat sink fins  342  and is formed by positioning internal heat sink fins  340  between external heat sink fins  342  in a sandwich fashion such that external heat sink fins  342  are disposed on the outer most portion of finned heat sink  300 . External heat sink fins  342  are disposed so as to be parallel to internal heat sink fins  340  such that core top  310  of each heat sink fin  304  is adjacent to the core top  310  of the neighboring heat sink fin  304 . Fin spacers  322  are non-movably disposed between heat sink fins  304  in a sandwich fashion so as to separate heat sink fins  304  from each other such that core bottom  312  is adjacent to spacer core bottom  330 . In addition, heat sink fins  304  are preferably thermally communicated with fin spacers  322  so as to allow efficient thermal transfer between heat sink fins  304  and fin spacers  322 . 
   Heat sink base  302  also includes a base bottom  344  having a bottom material layer  346  constructed of a thermally conductive material, wherein bottom material layer  346  is disposed so as to seal cover bottom  318  to core bottom  312  and spacer cover bottom  336  to spacer core bottom  330 . 
   The graphite-epoxy material of fin core  306  is advantageously contained within fin cover  308  preventing the contamination of neighboring hardware with graphite-epoxy debris. This is because cover top  316  is extended past core top  310  so as to contain graphite-epoxy debris and cover bottom  318  is sealed by bottom material layer  346  so as to enclose core bottom  312  within fin cover  308 . In addition, this advantageously allows fin core  306  to be contained with fin cover  308  without the problems associated with electroless nickel plating. 
   Although fin cover  308  is preferably constructed of 0.375 oz copper foil as known in the circuit board industry, fin cover  308  may be constructed of any material suitable to the desired end purpose, such as aluminum. In addition, although fin cover  308  is preferably a solid foil material, fin cover  308  may also be a screened foil material. Moreover, fin cover  308  may be processed to promote material adhesion via any method or device suitable to the desired end purpose such as roughening. 
   Although heat sink fins  304  and fin spacers  322  are preferably non-movably associated using a thermally conductive soldering material  348 , heat sink fins  304  and fin spacers  322  may be non-movably associated using any method and/or device suitable to the desired end purpose. In addition, bottom material layer  346  may be non-movably associated with base bottom  344  via any method and/or device suitable to the desired end purpose, such as electroplating, physical vapor deposition and/or sputtering. 
   In accordance with a third embodiment, fin cover  308  includes a copper-oxide treatment on fin cover face  309 . This copper-oxide treatment advantageously promotes the adhesion of fin cover face  309  to fin core  306 . Fin cover face  309  may be bonded to graphite-epoxy material of fin core  306  by compressing fin cover face  309  against fin core  306  while the graphite-epoxy material of fin core  306  is heated to a temperature range in which the graphite-epoxy material is pliable. This advantageously allows an epoxy-copper bond to form between fin cover face  309  and fin core  306 , wherein the epoxy-copper bond may withstand large temperature gradients such as those experienced in soldering operations. Although, fin cover  308  is preferably bonded to fin core  306  via a copper-oxide treatment, fin cover  308  may be bonded to fin core  306  using any adhesion promoting material, device or method suitable to the desired end purpose, such as Silane-based adhesion. 
   Referring to  FIG. 4 , a finned heat sink  400  in accordance with a fourth embodiment is shown and discussed. Finned heat sink  400  includes a heat sink base  402  and a plurality of heat sink fins  404 . Heat sink fins  404  include a fin core  406  and a fin cover  408 , wherein fin cover  408  is non-movably associated with fin core  406 . In addition, fin cover  408  is thermally communicated with fin core  406  so as to allow for a maximum amount of heat transfer. Fin core  406  includes a core top  410 , a core bottom  412  and has a core length  414 . Fin cover  408  includes a cover top  416 , a cover bottom  418  and a cover length  420 , wherein cover length  420  is preferably larger than core length  414 . Fin cover  408  is disposed relative to fin core  406  such that cover top  416  extends beyond core top  410  and cover bottom  418  is adjacent to core bottom  412 . 
   Heat sink base  402  is preferably constructed of a thermally conductive metallic material and includes a base top  420  having a plurality of fin slots  422 . Heat sink base  402  may be constructed of any thermally conductive material suitable to the desired end purpose such as a refractory ceramic (Aluminum-Oxide, Boron-Nitride, Silicon-Carbide). Plurality of heat sink fins  404  are non-movably associated with plurality of fin slots  422  such that heat sink fins  404  are thermally communicated with heat sink base  402  so as to allow efficient thermal transfer between heat sink fins  404  and heat sink base  402 . Finned heat sink  400  is formed by non-movably associating one heat sink fin  404  with one fin slot  422  until all of the plurality of fin slots  422  contain a heat sink fin  404 . 
   Although fin cover  408  is preferably constructed of 0.375 oz copper foil as known in the circuit board industry, fin cover  408  may be constructed of any material suitable to the desired end purpose. In addition, although fin cover  408  is preferably a solid foil material, fin cover  408  may also be a screened foil material. In accordance with a first embodiment, fin cover  408  includes a copper-oxide treatment on fin cover face  409 . This copper-oxide treatment advantageously promotes the adhesion of fin cover face  409  to fin core  406 . Fin cover face  409  may be bonded to graphite-epoxy material of fin core  406  by compressing fin cover face  409  against fin core  406  while the graphite-epoxy material of fin core  406  is heated to a temperature range in which the graphite-epoxy material is pliable. This advantageously allows an epoxy-copper bond to form between fin cover face  409  and fin core  406 , wherein the epoxy-copper bond may withstand large temperature gradients such as those experienced in soldering operations. Although, fin cover  408  is preferably bonded to fin core  406  via a copper-oxide treatment, fin cover  408  may be bonded to fin core  406  using any adhesion promoting material, device or method suitable to the desired end purpose, such as Silane-based adhesion. Moreover, fin cover  408  may be processed to promote material adhesion via any method or device suitable to the desired end purpose such as roughening. 
   Although heat sink fins  404  are preferably non-movably associated with fin slots  422  using a thermally conductive soldering material  424 , heat sink fins  404  may be non-movably associated with fin slots  422  using any method and/or device suitable to the desired end purpose. 
   While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.