PATENT DOCUMENT

Publication Number: US-7433191-B2
Application Number: US-24106105-A
Country: US
Kind Code: B2

Title: Thermal contact arrangement

Abstract:
A thermal contact arrangement. The thermal contact arrangement may mitigate or reduce migration over time of a thermal interface material positioned between a chip and a heat sink. The thermal contact arrangement may include a first zone formed on a first area of the heat sink and a second zone formed on a second area of the heat sink. The processor may overlap or overlie the first zone, with the second zone generally outside the footprint of the processor and optionally surrounding the processor&#39;s footprint. The first zone may have a generally smooth surface, while the second zone may have a surface rougher than the first zone. The first zone may be finished to a specific smoothness while the second zone may be finished to second particular smoothness that is generally less than the first zone.

Claims:
1. A thermal contact arrangement, comprising:
 a thermal conductor; 
 a first zone having a first surface finish disposed on the thermal conductor; and 
 a second zone having a second surface finish disposed on the thermal conductor; wherein 
 the first surface finish and second surface finish are different. 
 
   
   
     2. The thermal contact arrangement of  claim 1 , wherein the first surface finish is smoother than the second surface finish. 
   
   
     3. The thermal contact arrangement of  claim 2 , wherein:
 the first surface finish is approximately 4 microinches root mean square; and 
 the second surface finish is approximately 125 microinches root mean square. 
 
   
   
     4. The thermal contact arrangement of  claim 2 , wherein the second zone surrounds the first zone. 
   
   
     5. The thermal contact arrangement of  claim 4 , wherein the thermal conductor comprises a heat sink. 
   
   
     6. The thermal contact arrangement of  claim 5 , further comprising:
 a processor operatively connected to the heat sink; wherein 
 the first zone approximately corresponds to a footprint of the processor. 
 
   
   
     7. The thermal contact arrangement of  claim 6 , further comprising a thermal interface material disposed between the processor and heat sink and operative to thermally couple the processor and heat sink. 
   
   
     8. The thermal contact arrangement of  claim 6 , wherein:
 the first zone and second zone are formed directly from an external surface of the heat sink. 
 
   
   
     9. The thermal contact arrangement of  claim 8 , wherein the thermal interface material is disposed adjacent the first zone. 
   
   
     10. The thermal contact arrangement of  claim 9 , wherein:
 the second surface finish establishes a surface tension with the thermal interface material; and 
 the surface tension resists migration of the thermal interface material from the first zone. 
 
   
   
     11. A thermal contact arrangement, comprising:
 a carrier; 
 a processor disposed on the carrier; 
 a thermal interface material adjacent the processor; 
 a heat sink thermally coupled to the processor by the thermal interface material; wherein 
 the heat sink comprises:
 a first surface finish defining a first zone; and 
 a second surface finish defining a second zone, the second surface finish rougher than the first surface finish. 
 
 
   
   
     12. The thermal contact arrangement of  claim 11 , wherein the thermal interface material is chosen from the group comprising: a thermal grease; a thermal elastomer; an oxide-doped thermal grease; a metal-doped thermal grease; a thermal adhesive; and a metallic material. 
   
   
     13. The thermal contact arrangement of  claim 11 , wherein:
 a first side of the heat sink and a first side of the processor cooperate to form a thermal joint; 
 the thermal interface material occupies at least a portion of the thermal joint; and 
 the first zone and second zone are disposed on the first side of the heat sink. 
 
   
   
     14. The thermal contact arrangement of  claim 13 , wherein the second zone at least partially surrounds the first zone. 
   
   
     15. The thermal contact arrangement of  claim 14 , wherein an area of the first zone is greater than an area of the first side of the processor. 
   
   
     16. The thermal contact arrangement of  claim 14 , wherein an area of the first zone is less than an area of the first side of the processor. 
   
   
     17. The thermal contact arrangement of  claim 14 , further comprising a lid positioned over the processor.

Description:
BACKGROUND ART 
   1. Technical Field 
   The present invention relates generally to a thermal contact arrangement between a processor and a heat sink, and more particularly to a processor thermal contact having at least a first and a second surface finish of differing smoothness. 
   2. Background of the Invention 
   Processors (also referred to as “computer processors” or “processor chips”) are specialized electronic circuits providing computing functionality in a variety of modern electronics, such as computers or other computing devices, networking devices, and/or telecommunications devices. Processors (“chips”) may be responsible for the overall operation of a computing, telecommunications, or network device (such as a central processing unit, router or switch), operation or coordination of a device&#39;s subsystem (such as a graphics or sound processor), particular operations (such as a math coprocessor), and so forth. During operation, processors generate heat as a result of their operation. The processor may be attached to a carrier such as a circuit board, as shown in the prior art view of  FIG. 1 . 
   Generally speaking, excessive temperature may disrupt a processor&#39;s operation or, in more severe cases, damage the processor. Accordingly and as shown in  FIG. 1 , a heat sink may be affixed to the processor in order to dissipate thermal energy generated by the processor. Similarly, heat sinks may be attached to other computing elements that generate heat in order to transfer heat away therefrom and safely dissipate the heat. A heat sink is one example of a thermal conductor, which may then dissipate the heat to the air, a liquid, or other similar cooling sub-system 
   The interface between the processor and heat sink may be referred to as a “thermal joint.” The rate of conductive heat transfer, Q, across the interface may be further refined to include the effects of contact resistance which then can be approximated by 
   
     
       
         
           Q 
           = 
           
             
               KA 
               ⁡ 
               
                 ( 
                 
                   Tc 
                   - 
                   Ts 
                 
                 ) 
               
             
             L 
           
         
       
     
   
   where K is the thermal conductivity of an interface material (whether a dedicated thermal interface material discussed below, air, or another material), A is the heat transfer area, L is the interface thickness and Tc and Ts are the chip surface and heat sink temperatures. The thermal resistance of a thermal joint, Rc-s, is given by 
   
     
       
         
           
             Rc 
             ⁢ 
             
               - 
             
             ⁢ 
             s 
           
           = 
           
             
               ( 
               
                 Tc 
                 - 
                 Ts 
               
               ) 
             
             Q 
           
         
       
     
   
   and on rearrangement, 
   
     
       
         
           
             Rc 
             ⁢ 
             
               - 
             
             ⁢ 
             s 
           
           = 
           
             L 
             KA 
           
         
       
     
   
   Thus, the thermal resistance of the thermal joint is directly proportional to the thermal joint thickness and inversely proportional to the thermal conductivity of the medium making up the thermal joint and to the size of the heat transfer area. Thermal resistance may be minimized by making the thermal joint as thin as possible, increasing thermal joint thermal conductivity by eliminating interstitial air and making certain that both surfaces are in intimate contact. The thermal resistance of the thermal contact arrangement (which, in one example, includes the thermal joint, processor or chip, and heat sink) may be generally expressed as the thermal resistance of the thermal joint plus the thermal interface resistances of the chip and heat sink: 
   
     
       
         
           Rtotal 
           = 
           
             
               L 
               KA 
             
             + 
             
               Rc 
               ⁢ 
               
                 - 
               
               ⁢ 
               i 
             
             + 
             
               Rsi 
               ⁢ 
               
                 - 
               
               ⁢ 
               c 
             
           
         
       
     
   
   where Rtotal is the total resistance of the thermal contact arrangement, Rc-i is the thermal resistance between the chip and interface material and Ri-s is the thermal resistance between the interface material and the heat sink. 
     FIG. 2  is a cross-sectional diagram taken along line  2 - 2  of  FIG. 1 . As shown in  FIG. 2 , a thermal interface material (TIM) may be sandwiched or placed between the processor and the heat sink. The TIM may facilitate or enhance heat transfer between the processor and heat sink, thus potentially reducing the temperature experienced by the processor and/or extending the processor life. The TIM essentially performs the functions of eliminating at least some interstitial air pockets and enhancing contact between the processor and heat sink. Further, a TIM typically has a high thermal conductivity K than air, and thus enhances the rate of conductive heat transfer Q. 
   TIMs, however, may suffer from migration over time. Put simply, some TIMs tend to move away from the thermal joint with time, flowing or otherwise migrating out from the heat transfer surface area of the processor and/or heat sink. As the TIM migrates, air pockets may form in the thermal joint, and rate of conductive heat transfer between processor and heat sink may drop. Thus, as time passes, the aforementioned problems may occur even though a TIM is initially used. 
   SUMMARY OF THE INVENTION 
   One embodiment of the present invention generally takes the form of a surface positioned on a heat sink adjacent to which a processor may be affixed. The processor may overlap or overlie a first segment of the surface, with a second portion of the surface surrounding the first portion. Accordingly, the second portion generally lies outside the footprint of the processor and further surrounds the processor&#39;s footprint. The combination of first and second portions (alternately called “first and second zones” or “first and second surfaces”) may act to prohibit or at least reduce the migration of a thermal interface material positioned adjacent the first portion, as described in more detail below. 
   The first area or portion may have a generally smooth surface, while the second area or portion may have a surface rougher than the first area. That is, the first area may be finished to a specific smoothness while the second area may be finished to second particular smoothness that is generally less than the first area. It should be noted that the variations in surface finish between the first and second areas may be relatively small, on the order of microinches. It should also be noted that the variation in surface finish may not be readily detectable by human senses, such as sight or touch. 
   Another exemplary embodiment may take the form of a thermal contact arrangement, including a thermal conductor, a first zone having a first surface finish disposed on the thermal conductor, and a second zone having a second surface finish disposed on the thermal conductor, wherein the first surface finish and second surface finish are different. In certain embodiments, the first surface finish is smoother than the second surface finish. In yet further embodiments, the thermal conductor may be a heat sink. In still more embodiments, the thermal contact arrangement may include a processor operatively connected to the heat sink, wherein the first zone approximately corresponds to a footprint of the processor. A thermal interface material may be disposed within or adjacent to the first zone. 
   Yet another exemplary embodiment may take the form of a thermal contact arrangement including a carrier, a processor disposed on the carrier, a thermal interface material adjacent the processor, a heat sink thermally coupled to the processor by the thermal interface material. The heat sink may include a first surface finish defining a first zone, and a second surface finish defining a second zone, the second surface finish rougher than the first surface finish. In further embodiments, the thermal interface material may be a thermal grease, a thermal elastomer, an oxide-doped thermal grease, a metal-doped thermal grease, or a thermal adhesive. Alternative embodiments may use any of a number of similar materials as a TIM. In still other exemplary embodiments, a first side of the heat sink and a first side of the processor cooperate to form a thermal joint, the thermal interface material occupies at least a portion of the thermal joint, and the first zone and second zone are disposed on the first side of the heat sink. In some embodiments, the second zone at least partially surrounds the first zone. 
   Still another embodiment of the present invention may take the form of A method for manufacturing a thermal contact arrangement, including the operations of providing a thermal conductor, forming a first zone having a first roughness on a first exterior surface of the thermal conductor, and forming a second zone having a second roughness on the first exterior surface of the thermal conductor, wherein the second roughness is rougher than the first roughness. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  depicts a prior-art thermal contact arrangement between a processor and a heat sink. 
       FIG. 2  depicts a cross-sectional view of the thermal contact arrangement of  FIG. 1 , taken along line  2 - 2  of  FIG. 1 . 
       FIG. 3  depicts an exemplary processor (or other chip) mounted on an exemplary carrier, in accordance with a first embodiment of the present invention. 
       FIG. 4  depicts a cross-sectional view of the processor and carrier of  FIG. 3 , taken along line  3 - 3  of  FIG. 4 . 
       FIG. 5  is an expanded view of a portion of the cross-sectional view of  FIG. 4 . 
       FIG. 6  depicts an exemplary first zone and exemplary second zone formed on the surface of a heat sink in a first pattern, in accordance with the first embodiment of the present invention. 
       FIG. 7  depicts an exemplary first zone and exemplary second zone formed on the surface of a heat sink in a second pattern, in accordance with a second embodiment of the present invention. 
       FIG. 8  depicts an exemplary first zone and exemplary second zone formed on the surface of a heat sink in a third pattern, in accordance with a third embodiment of the present invention. 
       FIG. 9  depicts a cross-sectional view of a thermal contact arrangement similar to that of  FIG. 4 , but including a lid. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   One embodiment of the present invention generally takes the form of a surface positioned on a heat sink adjacent to which a processor may be attached. The processor may overlap or overlie a first segment of the surface of the heat sink, with a second portion of the surface surrounding the first portion. Accordingly, the second portion generally lies outside the footprint of the processor and further surrounds the processor&#39;s footprint. A processor or chip&#39;s “footprint” refers to that portion of the heat sink (or other element) having generally the same shape and area as the adjacent surface of the processor. 
   The first area or portion may have a generally smooth surface, while the second area or portion may have a surface rougher than the first area. That is, the first area may be finished to a specific smoothness while the second area may be finished to second particular smoothness that is generally less than the first area. It should be noted that the variations in surface finish between the first and second areas may be relatively small, on the order of microinches. It should also be noted that the variation in surface finish may not be readily detectable by human senses, such as sight or touch. 
     FIG. 3  depicts an exemplary processor (or other chip) mounted on an exemplary carrier, such as a graphics card, sound board, motherboard, or other computer, network, or telephony hardware, board or card. The exact function of the processor and/or board may vary. For example, the processor may be a dedicated graphics processor, a central processing unit, a memory processor, and so forth. Accordingly, it should be understood that various embodiments of the present invention may be used in any number of exemplary environments, networks, telephony systems or computer systems, and implemented on a wide variety of computer, network or telephony hardware (for example, the aforementioned boards or cards) and with any of a number of different types of processors. As yet another example, a smart card having an internal processor may employ an embodiment of the present invention, as may any other portable processing device. It should be understood that exemplary operating environments in which exemplary embodiments of the present invention may operate or be found include personal computers, network servers, microcomputers, minicomputers, desktop computers, notebook computers, mobile telephones, personal computing or scheduling devices, personal communication devices, switches, routers, tablet computing devices, digital entertainment devices such as MPEG Layer-3 (MP3) players or cameras, and so forth. 
   Returning to  FIG. 3 , a processor  100  is affixed to a carrier  105 . The processor  100  may be attached to the carrier  105  by one or more prongs or a socket extending through one or more vias and into the material of the carrier, solder, an adhesive, or by any other means known in the art. The carrier may be, for example, a printed circuit board (PCB) or other type of circuit board, integrated circuit or system-on-chip design, breadboard, stripboard, or other electrical component or appropriate material as known to those of ordinary skill in the art. 
   As shown in the cross-sectional view of  FIG. 4 , taken along line  4 - 4  of  FIG. 3 , disposed above the processor is a heat sink  110 . The heat sink  110  generally overlies the processor  100  or chip. The heat sink generally is a thermally conductive element, such as a metal, conducting heat away from the processor  100  and dissipating it to an environment or thermal mass capable of receiving and/or dissipating the heat. 
   As also shown in  FIG. 4 , in the present embodiment the heat sink  110  is not directly touching or directly adjacent to the processor  100  along the entirety of the processor&#39;s or heat sink&#39;s length. (In alternative embodiments, some or all of the heat sink  110  may contact the processor  100 ). Rather, a thermal interface material (TIM)  115  may be placed between the heat sink  110  and the processor  100 . The TIM  115  may be generally described as a material increasing thermal conductivity between the processor and heat sink. The TIM  115  accordingly facilitates heat flow between these two elements at the thermal joint  140  therebetween. 
   Typically, both the processor  100  and heat sink  110  have at least some surface irregularities, as shown to better effect in the expanded cross-sectional view of  FIG. 5 . In many cases, these surface irregularities are invisible to the human eye and/or undetectable to human touch. For example, the surfaces of both the processor  100  and heat sink  110  may have microscopic hills  120  and/or valleys  125 . These irregularities may be measured in microinches, depending on the finish and type of processor  100  and/or heat sink  110  employed. Similarly, either the processor  100  may have more macroscopic changes in surface. One or both of the processor and heat sink may be, for example, concave, convex twisted or otherwise non-planar along at least a portion of their facing surfaces. Thus, the processor and heat sink may abut at certain points along their surfaces, while being spaced apart at other points. The TIM  115  may at least partially fill in such valleys  125  and/or macroscopic features, thus replacing air that may otherwise reside between the processor  100  and heat sink  110 . The TIM  115  is typically a better heat conductor than air. 
   One or more of a variety of TIMs  115  may be placed between the processor  100  and heat sink  110  to facilitate heat transfer therebetween. For example, the TIM  115  may be a thermal grease (which may be silicone based), thermally conductive compound, thermally conductive elastomer (such as a pad), thermal grease with an oxide or metal filler, adhesive tape, and so forth. As a general rule, the TIMs mentioned herein may be ranked by thermal conductivity K from lowest conductivity to highest conductivity, as follows: thermal grease; elastomer or pad; thermal grease with an oxide filler; and thermal grease with a metal filler or metallic materials (such as solders). It should be noted this ranking is a general overview; the exact composition of a given TIM  115  may make it more or less conductive than the neighboring TIM on the scale given. Further, thermal greases and/or compounds typically have a lower interface resistance (that is, they spread more easily), but may be less convenient to apply than a thermal adhesive pad, for example. 
   A TIM  115  may migrate with time. When a TIM  115  migrates, it spreads or moves away from the interface or thermal joint  140  at which it was originally applied. TIM migration may lead to the formation of air pockets within the thermal joint  140 , and thus lowered thermal conductivity between the processor  100  and heat sink  110 . This, in turn, may lead to higher processor operating temperatures and cause errors during operation of the processor and possibly eventual damage to the processor. 
   To minimize, resist, or delay such migration, the surface of the heat sink  110  facing the processor  100  may define two distinct zones or areas, each with a separate surface finish.  FIGS. 4 and 6  depict an exemplary heat sink  110  surface defining a first zone  145  and a second zone  150 . As shown in  FIGS. 4 and 6 , the first zone  145  generally corresponds to the footprint (surface area) of the processor  100 , and forms one side of the thermal joint  140 . The first zone  145  may extend slightly beyond the footprint of the processor  100  in certain embodiments. In yet other embodiments, the first zone  145  may be slightly smaller than the processor&#39;s footprint. The second zone  150  generally surrounds the first zone  145 . The width of the second zone  150  may vary in different embodiments. In some embodiments, for example, the second zone  150  may extend from the outer edge of the first zone  145  to the heat sink edge. In still other embodiments, the second zone  150  may terminate before the heat sink edge is reached. The first zone and second zone may be contiguous, such that the border of the first zone abuts the border of the second zone (see  FIG. 4 ), or a gap or space may exist between zones. 
   In yet other embodiments, the second zone  150  may extend into the footprint of the processor  100  on the heat sink  110 , in some cases by a substantial amount. 
   As mentioned above, the first and second zones  145 ,  150  typically have different surface finishes, as shown in  FIG. 6 .  FIG. 6  is generally a plan view looking upward at the base of the heat sink  110 . In an exemplary embodiment, the first zone&#39;s surface finish is selected to facilitate heat transfer between the processor  100 , TIM  115 , and heat sink  110 , while the second zone&#39;s surface finish is selected to resist or delay TIM migration. 
   As one example of acceptable surface finishes relative to one another, the first zone  145  may have a relatively smooth surface finish and the second zone  150  may have a rougher finish. The relatively smooth surface finish of the first zone  145  may minimize or reduce hills  120  and/or valleys  125  formed on the heat sink  110 . This, in turn, enhances heat transfer from the processor  100  through the TIM  115 , since it maximizes the contiguous surfaces of the thermal joint  140 . 
   Continuing the example and by contrast, the second zone  150  may have a surface finish relatively rougher than that of the first zone  145 . This rougher surface finish may act to minimize or otherwise reduce spreading (i.e., migration) of the TIM  115  with time. More particularly, the rougher surface finish of the second zone  150  may create or enhance a surface tension with the material of the TIM  115 , thus confining the TIM to the smoother surface of the first zone  145 . The rougher the surface finish of the second zone, the greater the surface tension with the TIM material. Further, the greater the surface tension between the second zone and TIM, the more the TIM may resist migration. Certain TIMs may be more affected by this surface tension and thus resist migration more effectively. For example, a thermal grease may experience greater surface tension with the rough surface of the second zone  150  than would a pad or other elastomer. 
   In an exemplary embodiment of the present invention, the first zone  145  may have a surface finish on the order of four to 32 microinches root mean square (RMS), while the second zone  150  may have a surface finish on the order of 63 to 250 microinches root mean square. It should be understood that these ranges are exemplary, rather than limiting. Alternative embodiments may vary the actual surface finishes of either or both of the first and second zones  145 ,  150  from these ranges without departing from the spirit or scope of the invention. 
   Yet other embodiments of the present invention may define a third zone, fourth zone, or even more zones having varying surface finishes on the exterior of the heat sink. For example, in some embodiments a third zone may be formed about the second zone  150  and provided with a surface finish rougher than that of the second zone. This may provide still greater surface tension with the TIM  115  in the event the TIM migrates from adjacent the first zone  145  to a position adjacent the second zone  150 . 
   In still another embodiment, a third zone may surround the second zone  150  as described above, but have a smoother surface finish than the second zone. A fourth zone may surround the second zone and have a surface finish rougher than that of the third zone (for example, approximately equal to the roughness of the second zone&#39;s surface finish). In this manner, the third zone may act as a trough to capture any TIM  115  that moves or migrates past the second zone  150 . The combination of the fourth zone&#39;s and second zone&#39;s surface finish may establish a surface tension on either side of TIM migrating to (or abutting) the third zone. 
   The second zone  150  may be subdivided into a number of smaller “sub-zones” of varying surface finish. This may permit the second zone  150  to provide greater surface tension with the TIM  115  at certain areas of the heat sink (for example, those areas prone to migration of the TIM), and lesser surface tension with the TIM at other areas. Further, by providing varying surface finishes across the second zone  150 , the TIM  115  may be encouraged to migrate along a particular path. For example, the TIM may be encouraged to migrate to a collection point, or to a point easily visible to a casual observer. In this manner, migration of the TIM  115  may be more easily seen and the TIM may be replaced or replenished accordingly. 
   The TIM may be similarly encouraged to migrate in a particular manner by forming the second zone  150  into a particular pattern, as shown in  FIG. 7 . The second zone  150  may extend in a C-shape, U-shape or other shape, leaving an exit path  155  along which the TIM  115  may migrate. The exit path  155  may terminate in a collection reservoir  160 , which may be visible when the processor  100 , carrier  105 , and/or heat sink  110  are installed in an operating environment. Further, the second zone  150  (or another zone with a relatively rough surface finish) may surround the collection reservoir  160  to prevent the TIM  115  from migrating out of the reservoir. 
   In still further embodiments, the second zone  150  may be formed in one or more of a variety of unique patterns. The width of any portion of the second zone  150  may be varied, the second zone may be formed in a checkerboard pattern (as shown in  FIG. 8 , where shading indicates roughened surfaces of the second zone  150 ), and so forth. The exact configuration of the second zone  150 , as well as that of the first zone  145 , may vary depending on the size and/or shape of any of the processor  100 , heat sink  110 , and/or carrier  105 , as well as the operating environment of any of the foregoing. 
   The various surface finishes and zones  145 ,  150  described herein may be created or enhanced according to a variety of manufacturing processes. For example, the first zone  145  may be formed by polishing, grinding, chemically smoothing or otherwise smoothing an exterior surface of the heat sink  110 , while the second zone  150  may be formed from an unpolished or untreated exterior surface of the heat sink. Conversely, the first zone  145  may be formed on an untreated portion of the heat sink, while the second zone  150  may be formed by etching, eroding, scuffing or machining another portion of the sink  110 . Further, both zones may be formed through chemical or mechanical treatments. For example, the first zone may be a polished segment of the heat sink  110  and the second zone may be a chemically roughened segment. 
   The foregoing embodiments have generally been described with respect to a single processor  100  and single heat sink  110 . Alternative embodiments may employ multiple heat sinks with a single processor, or multiple processors with a single heat sink. For example, one heat sink  110  might cover two or more processors  100 . A first zone  145  may be formed about both processors and a second zone  150  about the first zone, in a manner analogous to that described above. In yet another embodiment, a first zone  145  may be formed around each processor, and a second zone  150  around each first zone (or a single second zone around both first zones). 
   Still other embodiments of the present invention may be used with a so-called “lidded” chip  100 , as shown in cross-section in  FIG. 9 . The cross-section of  FIG. 9  is similar to that of  FIG. 4 , but shows a lid  165  enclosing the processor  100 . The lid  165  may be connected or affixed to the carrier  105 . A first TIM  170  generally conducts heat from the processor to the lid. A heat sink  110  may be placed above the lid  165 , with a second TIM  175  conducting heat from the lid to the sink. The two TIMs  170 ,  175  may be of the same or differing materials. 
   A first zone  145  and second zone  150  may be formed in the heat sink surface as described above. Here, however, the first and second zones may cooperate to reduce migration of the second TIM  175 . Similarly, a first lid zone  145 ′ and second lid zone  150 ′ may be formed on an exterior surface of the lid adjacent the first TIM  170 . The first and second lid zones  145 ′,  150 ′ may cooperate as described herein to reduce migration of the first TIM  170 . Accordingly, each TIM  170 ,  175  may have a unique set of first and second zones. 
   The present invention has been generally described with the various surface finishes and/or zones (such as the first and second zones) being formed on or otherwise associated with a surface of the heat sink. It should be understood, however, that such surface finishes and/or zones may alternately be formed on a surface of a chip or processor facing or adjacent to a TIM. In still other embodiments, the various surfaces and/or zones described herein may be formed on both a chip surface and heat sink surface. 
   The present invention and its various embodiments have been described herein with respect to particular apparatuses and methods. However, those of ordinary skill in the art will realize that alternative embodiments of the present invention may be formed by rearranging, adding or subtracting certain elements, or by making other changes to the embodiments described herein. Accordingly, the various embodiments described herein are intended to be exemplary and not limiting. The proper scope of the invention is defined by the appended claims.

Metadata:
Filing Date: 20050930
Publication Date: 20081007
Grant Date: 20081007
Priority Date: 20050930
Inventors: BLANCO, JR. RICHARD LIDIO
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T29/49126", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L23/433", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/4935", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/10158", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49128", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49128", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L2924/10158", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/433", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49169", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/4935", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L23/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49169", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49126", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 37901678