Abstract:
Heat sink apparatuses comprising a heat sink and a mounting fixture attached to the heat sink are provided. The mounting fixture is selected from the group consisting of dentate mounting fixtures, fenestrated mounting fixtures, and cavitated mounting fixtures. Also provided are heat sink assemblies including devices attached to heat sink apparatuses, methods of mounting devices to heat sink assemblies, and methods of making heat sink apparatuses.

Description:
BACKGROUND  
       [0001]     The field of the invention pertains to heat sink assemblies and methods of attaching devices to heat sinks.  
         [0002]     Devices such as integrated circuits, capacitors, power amplifiers, and other electronic components generate heat as electric current passes through the device. Generally, this heat must be dissipated as the device may fail if its temperature rises above some critical temperature. In general, the attachment of devices to heat sinks to aid in the dissipation of heat is known.  
         [0003]     In practice, a device may be attached to the heat sink first, followed by mounting the device, and optionally the heat sink, to a substrate such as a printed circuit board. Generally, the device must be precisely aligned on, and securely attached to the heat sink to prevent misalignment of the device with the substrate.  
         [0004]     Currently, a thermal interface pad is placed between the device and the heat sink and both are held in place by a mechanical device such as a clip in combination with nuts and bolts. Alternatively, thermal transfer tape is used to attach the device to the heat sink. Given the need to prevent air gaps, soft and conformable tapes are used. Generally, these methods do not offer sufficient torque, shear, tensile, or cleavage holding strength when the device is inserted into a substrate. This can result in misalignment between the device and the substrate, and damage to the device during mounting, handling, and use.  
       SUMMARY  
       [0005]     Briefly, in one aspect, the present invention provides a heat sink apparatus comprising a heat sink having a mounting surface and a mounting fixture attached to the heat sink, wherein the mounting fixture is selected from the group consisting of a dentate mounting fixture, a fenestrated mounting fixture, and a cavitated mounting fixture.  
         [0006]     In some embodiments, the heat sink apparatus further comprises an adhesive member comprising a first surface and a second surface, wherein the first surface of the adhesive member is adhered to the mounting surface of the heat sink and the mounting fixture is adhered to at least a portion of the second surface of the adhesive member.  
         [0007]     In some embodiments, at least one of the heat sink and the mounting fixture further comprises structural restraining features.  
         [0008]     In some embodiments, the mounting fixture is a cavitated mounting fixture further comprising a pressure-invertible dimple.  
         [0009]     In another aspect, the present invention provides a heat sink assembly comprising a heat sink having a mounting surface; a mounting fixture attached to the heat sink, wherein the mounting fixture is selected from the group consisting of a dentate mounting fixture, a fenestrated mounting fixture, and a cavitated mounting fixture; and a device attached to the heat sink.  
         [0010]     In some embodiments, the heat sink assembly further comprises a substrate, wherein the device is attached to the substrate.  
         [0011]     In yet another aspect, the present invention provides a method of mounting a device to a heat sink comprising providing the heat sink apparatus comprising a heat sink and a mounting fixture; aligning the device relative to one or more features of the mounting fixture; and adhering the device to the heat sink apparatus.  
         [0012]     In yet another aspect, the present invention provides a method of making a heat sink apparatus comprising providing a heat sink; and attaching at least one mounting fixture selected from the group consisting of a dentate mounting fixture, a fenestrated mounting fixture, and a cavitated mounting fixture to the heat sink.  
         [0013]     In some embodiments, the mounting fixture is attached to the heat sink with an adhesive.  
         [0014]     In some embodiments, the mounting fixture is attached to the heat sink with one or more structural restraining features.  
         [0015]     In some embodiments, the mounting fixture is wrapped around one or more edges of the heat sink.  
         [0016]     The above summary of the present invention is not intended to describe each embodiment of the present invention. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1A  illustrates an exploded view of an exemplary heat sink apparatus of the prior art.  
         [0018]      FIG. 1B  illustrates the heat sink apparatus of  FIG. 1A  mounted to a substrate.  
         [0019]      FIG. 2A  illustrates an exploded view of a heat sink apparatus with a dentate mounting fixture in accordance with an embodiment of the invention.  
         [0020]      FIG. 2B  illustrates the heat sink apparatus of  FIG. 2A  mounted to a substrate.  
         [0021]      FIGS. 3A-3D  illustrate exemplary heat sinks having structural restraining features in accordance with embodiments of the present invention.  
         [0022]      FIG. 4  illustrates a heat sink apparatus with a dentate mounting fixture in accordance with another embodiment of the invention.  
         [0023]      FIGS. 5A-5D  illustrate a variety of edge patterns in accordance with some embodiments of the invention.  
         [0024]      FIG. 6  illustrates a heat sink apparatus with a fenestrated mounting fixture in accordance with an embodiment of the invention.  
         [0025]      FIG. 7  illustrates a heat sink apparatus with a cavitated mounting fixture in accordance with an embodiment of the invention.  
         [0026]      FIG. 8A  illustrates a heat sink apparatus with a dimpled cavitated mounting fixture prior to compression of the dimple, in accordance with an embodiment of the invention.  
         [0027]      FIG. 8B  illustrates a heat sink apparatus with a dimpled cavitated mounting fixture after compression of the dimple, in accordance with an embodiment of the invention.  
         [0028]      FIG. 9  illustrates a plurality of mounting fixtures formed from a web.  
         [0029]      FIG. 10  illustrates a plurality of mounting fixtures formed from a web including score lines.  
         [0030]      FIG. 11  illustrates a scored mounting fixture folded over an edge of a heat sink in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0031]     In some applications, it is desirable to attach a device to a heat sink prior to mounting the device on a substrate, such as, e.g., a printed circuit board (PCB). For example, one method of mounting a device and a heat sink to a printed circuit board comprises attaching a device to the mounting surface of a heat sink, temporarily mounting the device to the PCB by mating pins on the device, and optionally on the heat sink, with corresponding holes in the PCB, and wave soldering the device to the PCB.  
         [0032]     Generally, the pins substantially align with the holes in the PCB. If the pins are not substantially aligned, the pins and/or the device may become damaged during the attachment or subsequent use of the device. Generally, when the pins on the device are inserted into the holes in the PCB, forces (e.g., shear, torsion, tensile, and cleavage forces) may arise at the interface between the device and the mounting surface of the heat sink. These forces may shift the position of the device and its pins, resulting in misalignment with the mounting holes and ultimately damage to the mounting pins. These forces may also separate the device from the mounting surface of the heat sink. This separation can lead to poor thermal performance and reduce device reliability.  
         [0033]     Generally, it is desirable to secure the device to the heat sink. Referring to  FIGS. 1A and 1B , a prior art heat sink apparatus is shown. Generally, a thermally conductive material is positioned between a device (e.g., an integrated circuit, capacitor, power amplifier, power transistor device, FETS, or MOSFETS) and the mounting surface of a heat sink. A mechanical mechanism (e.g., a spring clip or a screw) is then used to hold the device in position as the device and heat sink apparatus are mounted to a substrate.  
         [0034]     More specifically,  FIGS. 1A and 1B  illustrate heat sink apparatus  100  including heat sink  110  having mounting surface  112  and heat-dissipating structure  114 . Heat-dissipating structure  114  comprises fins  116 . Generally, a heat sink may have a plurality of mounting surfaces. In some embodiments, heat sink  110  has a second mounting surface opposite mounting surface  112 .  
         [0035]     First surface  121  of thermally conductive material  120  is adhered to mounting surface  112 . Mounting bracket  130 , comprising mounting bar  131  and spring clips  132 , is positioned on heat sink  110  by aligning mounting bracket mounting holes  133  with heat sink mounting holes  113 . Devices  190  are positioned adjacent second surface  122  of material  120 , with one device  190  under each spring clip  132 . Mounting pins  195  extend from each device  190 . Generally, the location of each spring clip  132  aids in positioning and aligning a device. Bolts  141  are then passed through mounting holes  113  and  133  and nuts  142  are threaded onto bolts  141 , securing mounting bracket  130  to heat sink  110 . A spring force biases spring clip  132  against exposed surface  192  of device  190 , securing it in place.  
         [0036]     Referring to  FIG. 1B , mounting pins  195  on device  190  are aligned with substrate mounting holes  183  on substrate  180 . Force F is applied to heat sink apparatus  100  and/or substrate  180  to securely insert mounting pins  195  into substrate mounting holes  183 . During this mounting process, device  190  is subjected to forces that may shift the position of device  190  relative to heat sink  110 . In turn, this may result in misalignment of, and damage to mounting pins  195 , as well as separation of device  190  from mounting surface  112  of heat sink  110 . The spring force applied by mounting bracket  130  is intended to minimize this shifting.  
         [0037]     While prior art mechanical mechanisms address some of the problems encountered when mounting devices and a heat sink to a substrate, further improvements are desired. For example, prior art mechanical mechanisms generally require numerous parts that must be positioned and held in place, along with the devices, while screws or bolts are threaded in place. This may become particularly cumbersome when multiple devices (e.g., 2, 4, 8 or more devices) are mounted on a single heat sink. Also, while clips may aid in aligning the devices relative to the heat sink, lateral misalignment of the devices under the clips may still occur, resulting in misalignment of the mounting pins with the mounting holes. Finally, prior art mechanical mechanisms such as screws and spring clips provide restraint perpendicular to the mounting surface of the heat sink, but may not provide sufficient lateral support. Thus, as torsional forces arise during mounting, the devices may twist resulting in misalignment of the mounting pins and the mounting holes. This problem is exacerbated when multiple devices are present on a single heat sink.  
         [0038]     In some embodiments, the present invention aids in the lateral and vertical alignment of devices on the mounting surface of a heat sink. In some embodiments, the present invention restrains the motion of a device relative to the mounting surface of a heat sink as the mounting pins on the device and heat sink are inserted into the holes on a substrate, and/or as the apparatus and device are handled or used. In some embodiments, motion of the device parallel to the mounting surface of the heat sink is restrained. In some embodiments, motion of the device perpendicular to the mounting surface of the heat sink is restrained.  
         [0039]     Referring to  FIGS. 2A and 2B , an exemplary heat sink apparatus of the present invention is illustrated. Heat sink apparatus  200  includes heat sink  210 , adhesive member  250 , and dentate mounting fixture  260 . Heat sink  210  comprises mounting surface  212  and heat-dissipating structure  214  comprising fins  216 . First surface  251  of adhesive member  250  is adhered to mounting surface  212  of heat sink  210 . Dentate mounting fixture  260  is adhered to second surface  252  of adhesive member  250 .  
         [0040]     Generally, the shape of a heat sink can vary widely depending, for example, on the heat load, the size and number of devices mounted to it, and the space available. Any known heat sink including, e.g., heat spreaders and heat dissipaters, can be used with the present invention.  
         [0041]     In some embodiments, adhesive member  250  comprises a layer of adhesive. The adhesive may be applied in any form including, e.g., solids, liquids, pastes, foams, or gels. In some embodiments, the adhesive may be curable (e.g., moisture curable, reactively curable (e.g., two-part adhesives), thermally curable, or actinic radiation (e.g., UV) curable). In some embodiments, adhesive member  250  comprises a laminating adhesive (e.g., a free-film adhesive). In some embodiments, adhesive member  250  comprises a double-sided adhesive tape (i.e., a carrier (e.g., paper, polymer film, metal) with an adhesive on both major surfaces of the carrier). In some embodiments, adhesive member  250  is thermally conductive and/or electrically insulative. In some embodiments, thermally conductive filler(s) may be added to materials of this invention to increase the thermal conductivity. Addition of thermally conductive fillers may affect the mechanical and physical properties of the invention. One skilled in the art can adjust formulas and filler amounts and filler surface treatment to provide both thermal conductivity and suitable adhesive performance.  
         [0042]     In some embodiments, the thermally conductive fillers are selected from a variety of materials having a bulk conductivity of at least 5 Watts/meter-Kelvin (W/mK) (in some embodiments, at least 150 W/mK, and even at least 1000 W/mK) as measured according to ASTM D1530. Exemplary thermally conductive fillers include ceramics (e.g., aluminum oxide, boron nitride, silicon carbide, and aluminum nitride), metals (e.g., nickel, silver, gold, copper, iron, and aluminum), magnesium hydroxide, aluminum hydroxide, carbon, diamond, and the like.  
         [0043]     In some embodiments, the conductive fillers may comprise fibers, particulates, platelets, needles, whiskers, nanoparticles (e.g., solid and/or hollow nanospheres), spheres, flakes, agglomerates, and the like. In some embodiments, the fillers comprise particles coated with a thermally conductive material (e.g., a metal). Generally, the choice of shape is dependent upon the rheology of the selected adhesive resin and ease of processing of the final resin/particle mix.  
         [0044]     Generally, the larger the particle size of the filler, the higher will be the resultant final conductivity. Generally, a mixture of particle sizes can result in improved packing density that improves the resultant conductivity. Combinations of different fillers may be used. For example, a combination of fillers may provide equivalent thermal performance at reduced costs by substituting a portion of an expensive filler (e.g., boron nitride) with a cheaper filler (e.g., silicon carbide).  
         [0045]     Fillers may be available in several crystal types (e.g., hexagonal and rhombic boron nitride) and, generally, the type of crystal chosen will depend upon the thermal conductivity of the crystal (including the anisotropic nature of the conductivity along different crystal axes), the effect of crystal type on final mechanical properties, and cost. Fillers often have anisotropic thermal conductivity along various crystal planes; therefore, filler orientation may be used to enhance thermal performance. In some embodiments, the filler has a bulk thermal conductivity in one direction of at least 5 W/mK (in some embodiments, at least 150 W/mK, or even at least 1000 W/mK).  
         [0046]     Particle size and distribution may also affect mechanical properties, and particle size selection can take into account the requirements for good final adhesive strength. Generally, the particle size of the filler (or mixture of fillers) and particle loading are selected to produce suitable thermal conductance while retaining adequate mechanical properties. Particle size is the length of the major axis of a particle. In some embodiments, the particle size of the filler is greater than 2 microns (in some embodiments, greater than 5 microns, or even greater than 10 microns.) In some embodiments, the particle size of the filler is less than 200 microns (in some embodiments, less than 100 microns, and even less than 50 microns).  
         [0047]     Dentate mounting fixture  260  comprises teeth  261  and bridge  263 . Gaps  262  are defined by the space adjacent a tooth, and are bounded by bridge  263  and at least one tooth  261 . Dentate mounting fixture  260  is adhered to at least a portion of second surface  252  of adhesive member  250 . Generally, bridge  263  and teeth  261  are adhered to adhesive member  250 . In some embodiments, exposed adhesive may extend beyond the edges of dentate mounting fixture  260  and the areas exposed by gaps  262 .  
         [0048]     Device  290  is substantially aligned within gap  262  and adhered to at least a portion of second surface  252  of adhesive member  250  located within gap  262 . Generally, the location and dimensions of gap  262  are determined by, e.g., the dimensions of device  290  and the desired location of device  290  relative to a substrate to which it will ultimately be mounted. In some embodiments, a gap is wide enough to accommodate one device. In some embodiments, a gap is wide enough to accommodate two or more devices.  
         [0049]     Top edge  264  of gap  262  aids in the vertical alignment of device  290  relative to lower edge  213  of heat sink  210 . Side edges  265  and  266  aid in the lateral alignment of device  290  relative to mounting surface  212  of heat sink  210 . In some embodiments, device  290  will be positioned adjacent to, and substantially aligned with one or more teeth  261 , and optionally bridge  263 . In some embodiments, the device is less than about 5 millimeters (mm) from at least one edge (in some embodiments, less than about 1 mm, or even less than 0.1 mm). In some embodiments, device  290  may abut one or more edges. Generally, the teeth are sized and spaced to allow one or more devices to be positioned within a gap.  
         [0050]     Referring to  FIG. 2B , mounting pins  295  on device  290  are aligned with substrate mounting holes  283  on substrate  280 . Force F is applied to heat sink apparatus  200  and substrate  280  to securely insert mounting pins  295  in substrate mounting holes  283 . During this mounting process, device  290  is subjected to shear forces S and torsion forces T. In some embodiments, tension and cleavage forces may also be present. Generally, teeth  261  and, optionally, bridge  263  resist displacement of device  290  and minimize motion and the corresponding misalignment of mounting pins  295  relative to mounting holes  283 .  
         [0051]     In some embodiments, the mounting fixture can be attached to the heat sink using a single-sided tape. For example, a piece of single-sided tape may be adhered to both the mounting fixture and the heat sink securing them together. In some embodiments, the single-sided tape may cover a portion of the devices.  
         [0052]     In some embodiments, the mounting fixture may be attached to the heat sink using mechanical retention features. Generally, the retention features provide snap, press, compression, or interference fit. Referring to  FIGS. 3A-3D , additional exemplary heat sink apparatuses of the present invention are illustrated. Any known structural restraining features may be used including tabs, pins, and clips.  
         [0053]     Referring to  FIG. 3A , heat sink apparatus  301  includes heat sink  310  and dentate mounting fixture  366 . Heat sink  310  and dentate mounting fixture  366  comprise corresponding structural restraining features which allow dentate mounting fixture  366  to be attached to mounting surface  312 . The structural restraining features comprise flange  311  and corresponding edge  361 , wherein edge  361  is positioned between flange  311  and mounting surface  312 .  
         [0054]     Referring to  FIG. 3B , heat sink apparatus  302  includes heat sink  310  and dentate mounting fixture  367 . Heat sink  310  and dentate mounting fixture  367  comprise corresponding structural restraining features which allow dentate mounting fixture  367  to be attached to mounting surface  312 . The structural restraining features comprise opening  313  and tab  363 , wherein tab  363  may be inserted into opening  313 .  
         [0055]     Referring to  FIG. 3C , heat sink apparatus  303  includes heat sink  310  and dentate mounting fixture  368 . Heat sink  310  and dentate mounting fixture  368  comprise corresponding structural restraining features which allow dentate mounting fixture  368  to be attached to mounting surface  312 . The structural restraining features comprise post  314  and corresponding hole  364 , wherein post  314  may be inserted into hole  364 . Generally, any known post shape may be used to promote engagement in the hole. Exemplary post shapes include Christmas tree, conical, button, and mushroom. In some embodiments, the post may have serrated edges.  
         [0056]     Referring to  FIG. 3D , heat sink apparatus  304  includes heat sink  310  and dentate mounting fixture  369 . Heat sink  310  and dentate mounting fixture  369  comprise corresponding structural restraining features which allow dentate mounting fixture  369  to be attached to mounting surface  312 . The structural restraining features comprise lip  315 , which wraps around an edge of heat sink  310 .  
         [0057]     In some embodiments, additional structural features such as hooks, loops, or protrusions may be used. In some embodiment, the location of the retention features is reversed, e.g., posts may be located on the heat sink with corresponding holes in the mounting fixture. In some embodiments, the heat sink apparatus comprises a plurality of structural restraining features. In some embodiments, two or more different structural restraining features are present.  
         [0058]     Generally, any size, shape, and location of structural restraining features may be used. In some embodiments, the use of structural restraining features allows for easier removal and reuse of the mounting fixture, and or the heat sink.  
         [0059]     Referring to  FIG. 4 , another exemplary heat sink apparatus of the present invention is illustrated. Heat sink apparatus  400  includes heat sink  410 , adhesive member  450  adhered to mounting surface  412 , and dentate mounting fixture  460  adhered to adhesive member  450 .  
         [0060]     Dentate mounting fixture  460  comprises teeth  461  and bridge  463 . Gaps  462  are defined by the space adjacent a tooth, and are bounded by bridge  463  and at least one tooth  461 . Dentate mounting fixture  460  is adhered to at least a portion of adhesive member  450 . In some embodiments, substantially all of dentate mounting fixture  460  is adhered to adhesive member  450 . In some embodiments, only a portion of dentate mounting fixture  460  is adhered to adhesive member  450 .  
         [0061]     Thermally conductive material  470  is positioned within gaps  462 . In some embodiments, thermally conductive material  470  is electrically insulative. In some embodiments, the thermally conductive material comprises a thermally conductive adhesive. In some embodiments, the thermally conductive material comprises a single layer. In some embodiments, the thermally conductive material comprises a plurality of layers (e.g., 2, 3, or more layers.) For example, thermally conductive material  470  may comprise three layers: a first adhesive layer, a thermally conductive layer, and a second adhesive layer. In some embodiments, the first adhesive layer is thermally conductive and, optionally, electrically insulative. In some embodiments, the second adhesive layer is thermally conductive and, optionally, electrically insulative. In some embodiments, the thermally conductive layer is electrically insulative.  
         [0062]     One or more devices  490  are substantially aligned within gap  462  and adhered to at least a portion of thermally conductive material  470 . In some embodiments, device  490  is adhered directly to conductive material  470 . In some embodiments, a separate adhesive (e.g., a liquid adhesive or a layer of adhesive) is used to adhere device  490  to thermally conductive material  470 .  
         [0063]     Generally, the location and dimensions of gap  462  is determined by, e.g., the dimensions of device  490  and the desired location of device  490  relative to a substrate to which it will ultimately be mounted. Top edge  464  of gap  462  aids in the vertical alignment of device  490  relative to lower edge  413  of heat sink  410 . Side edges  465  and  466  aid in the lateral alignment of device  490  relative to mounting surface  412  of heat sink  410 .  
         [0064]     In the preceding figures, the top and side edges of the gaps are shown as substantially straight. However, any known shape may be used. For example, sawtooth, curved, waved, and dentate edge patterns are shown in  FIGS. 5A, 5B ,  5 C, and  5 D, respectively. In some embodiments, a different edge shape will be used on the top edge compared to the side edges. In some embodiments, a different edge shape may be used on one side edge relative to the other side edge.  
         [0065]     In some embodiments, the edge shape may be selected to enhance the compression fit of a device within a gap. That is, the edge shape may be selected such that a portion of the edge must be compressed as the device is inserted in the gap. The compression of the edges will result in lateral forces being exerted on the corresponding edges of the device that will aid in holding the device in place. Edge shape may also be selected to enhance the resistance to shear and torsion forces. In some embodiments, the edge shape may be selected to increase resistance to torsion forces at the comers of a device.  
         [0066]     Referring to  FIG. 6 , a fenestrated mounting fixture  660  according to an embodiment of the present invention is illustrated. Fenestrated mounting fixture  660  comprises windows  662  bounded by upper rail  663 , lower rail  665 , and stiles  661 . Fenestrated mounting fixture  660  may be attached to the heat sink with an adhesive member and/or one or more structural restraining features. One or more devices may be aligned within a window and adhered to the mounting surface.  
         [0067]     In some embodiments, at least a portion of the adhesive member is present within window  662  of fenestrated mounting fixture  660 , and a device is adhered to the adhesive member. In some embodiments, a thermally conductive material is present within window  662 , and the device is adhered to the thermally conductive material.  
         [0068]     Generally, the location and dimensions of windows  662  are determined by, e.g., the dimensions of the devices and the desired location of the devices relative to a substrate to which it will ultimately be mounted. Top rail  663  and lower rail  665  of window  662  aid in the vertical alignment of a device relative to the lower edge of a heat sink. Stiles  661  aid in the lateral alignment of a device relative to the mounting surface of a heat sink. In some embodiments, a device will be positioned adjacent to, and substantially aligned with one or more rails or stiles. In some embodiments, a device may abut one or more rails or stiles.  
         [0069]     Generally the edge shape of each rail and stile may be independently selected. Any known edge shape may be used. In some embodiments, edge shape may be selected to enhance the compression fit of a device within a gap. In some embodiments, edge shape may be selected to enhance resistance to shear and/or torsion forces.  
         [0070]     Referring to  FIG. 7 , cavitated mounting fixture  760 , according to an embodiment of the present invention, is shown. Cavitated mounting fixture  760  comprises cavity  762  bounded by bridge  763 , edges  765  and  766 , and cover  767 . In some embodiments, a cavitated mounting fixture comprises a plurality of cavities. Cavitated mounting fixture  760  may be adhered to the heat sink and/or attached using structural restraining features. One or more devices may be aligned within and inserted into cavity  762 . In some embodiments, at least a portion of the adhesive member is present within cavity  762  of cavitated mounting fixture  760 , and a device is adhered to the adhesive member. In some embodiments, a thermally conductive material is present within cavity  762 , and a device is adhered to the thermally conductive material.  
         [0071]     Generally, the location and dimensions of cavities  762  are determined by, e.g., the dimensions of the devices and the desired location of the devices relative to a substrate to which it will ultimately be mounted. Bridge  763  aids in the vertical alignment of device  790  relative to the lower edge of a heat sink. Edges  765  and  766  aid in the lateral alignment of a device relative to the mounting surface of a heat sink. In some embodiments, the device will be positioned adjacent to, and substantially aligned with bridge  763  and/or one or more of edges  765  and  766 . In some embodiments, the device may abut one or more of bridge  763  and edges  765  and  766 .  
         [0072]     In some embodiments, cover  767  aids in reducing separation of device  790  from the mounting surface of the heat sink. In some embodiments, bridge  763  and edges  765  and  766  aid in restraining device  790 , which reduces motion and misalignment of the device during mounting and use.  
         [0073]     Referring to  FIGS. 8A and 8B , another exemplary heat sink apparatus of the present invention is illustrated. Cavitated mounting fixture  860  comprises cavity  862  bounded by a bridge (not shown), edges  865  and  866 , and cover  867 . Cover  867  comprises pressure-invertible dimple  868 , which extends away from mounting surface  812 . Cavitated mounting fixture  860  is adhered to adhesive member  850 , which is adhered to heat sink  810 . In some embodiments, a cavitated mounting fixture may be attached to a heat sink using structural retaining features. Device  890 , comprising pins  895 , is aligned within and inserted into cavity  862 . In some embodiments, device  890  is adhered to heat sink  810 .  
         [0074]     In some embodiments, adhesive member  850  is thermally conductive and, optionally, electrically insulative. In some embodiments, at least a portion of adhesive member  850  is present within cavity  862  of cavitated mounting fixture  860 , and device  890  is adhered to adhesive member  850 . In some embodiments, a thermally conductive material is present within cavity  862 , and device  890  is adhered to the thermally conductive material.  
         [0075]     Referring to  FIG. 8B , pressure-invertible dimple  868  is compressed and at least partially inverted such that a least a portion of dimple extends towards mounting surface  812 . In some embodiments, when dimple  868  is in the extended position, device  890  will be easier to insert into cavity  862 . In some embodiments, when dimple  868  is compressed, dimple  868  will aid in reducing separation of device  890  from heat sink  810 . In some embodiments, cavitated mounting fixture  860  will comprise a plurality of dimples. In some embodiments, individual dimples may be selectively compressed to create cavities.  
         [0076]     Generally, mounting fixtures and devices may be attached to one or more surfaces of a heat sink. In some embodiments, mounting fixtures and devices are attached to opposing surfaces of a heat sink.  
         [0077]     The mounting fixtures of the present invention may comprise any known material including, for example, metal, paper, ceramic, rubber or elastomers, fiberglass, wood, polymeric films, and combinations thereof. In some embodiments, the mounting fixture comprises a polymeric film. In some embodiments, the polymeric film comprises polyester, polyamide, polyimide, polyolefin (e.g., polyethylene or polypropylene), polymethylmethacrylate (PMMA), polystyrene, ABS, PVC, and/or polycarbonate. In some embodiments, the material may be foamed. Generally, the material(s) comprising the mounting fixture may be selected based on, for example, mechanical properties (e.g., tensile strength, compressive strength, and bending stiffness), density, conductive properties (e.g., thermal conductivity and/or electrical conductivity), and cost. Generally, materials having higher compressive strength and/or bending stiffness are preferred. In some embodiments, the mounting fixture comprises multiple layers.  
         [0078]     The mounting fixtures of the present invention may be of any thickness. Generally, the thickness of the mounting fixture is less than the thickness of the devices being mounted to the heat sink. In some embodiments, the thickness of the mounting fixture is selected such that the top surface of the fixture is further from the mounting surface of the heat sink then are the pins on the device. In some embodiments, the combined thickness of the mounting fixture and the adhesive layer used to mount the fixture to the heat sink is selected such that the top surface of the fixture is further from the mounting surface of the heat sink then are the pins on the device. In some embodiments, the thickness of the mounting fixture is greater than about 10 microns (μm) (in some embodiments, greater than about 100 μm, greater than about 0.5 millimeter (mm), or even greater than about 2 mm). In some embodiments, the thickness of the mounting fixture is less than about 10 mm (in some embodiments, less than about 5 mm, or even less than about 3 mm).  
         [0079]     The mounting fixture of the present invention can be formed by any known process. For example, in some embodiments, the mounting fixtures may be formed by casting or extruding a polymeric film and subsequently punching or die-cutting teeth, gaps, and or windows into the film. In some embodiments, the mounting fixtures may be formed by blow molding, extrusion molding, compression molding, injection molding, stamping, laser cutting, thermo-forming, etching, and the like.  
         [0080]     In some embodiments, the mounting fixtures can be formed from a web of material, e.g., a polymeric film. In some embodiments, a plurality of mounting fixtures can be formed in the web of material as illustrated in  FIG. 9 . Referring to  FIG. 9 , openings  905  can be formed in substrate  900  by, e.g., die cutting. Substrate  900  may then be slit along lines  911  and  912  to form individual dentate mounting fixtures.  
         [0081]     In some embodiments, mounting fixtures of the present invention can be formed with an integral adhesive member by applying (e.g., coating, or extruding) an adhesive (e.g., a thermally conductive adhesive) onto a polymeric film. In some embodiments, the adhesive and polymeric film may be co-extruded. In some embodiments, the adhesive may be laminated to the polymeric film.  
         [0082]     In some embodiments, one or more adhesive members may be applied to the mounting surface of a heat sink. Then, one or more mounting fixtures (e.g., dentate, fenestrated, and/or cavitated mounting fixtures) may be applied to one or more of the adhesive members. One or more devices may then be aligned with a gap, window, or cavity and adhered to the mounting surface. In some embodiments, the device will be adhered to the adhesive member. In some embodiments, a thermally conductive material will be positioned within a gap, window, or cavity and adhered to the mounting surface of the heat sink. One or more devices may then be aligned with a gap, window, or cavity and adhered to the thermally conductive material.  
         [0083]     In some embodiments, a thermally conductive material may be applied to the mounting surface of the heat sink. In some embodiments, one or more adhesive members may be aligned with the thermally conductive material and adhered to the heat sink. One or more mounting fixtures may then be adhered to the adhesive member(s).  
         [0084]     In some embodiments, an adhesive member may be applied to the mounting fixture and the adhesive member and mounting fixture adhered to the mounting surface of the heat sink. In some embodiments, both mounting fixture(s) and device(s) may be adhered to an adhesive member and subsequently adhered to the heat sink. In some embodiments, a thermally conductive material may be adhered to a device and the thermally conductive material and device subsequently adhered to the heat sink.  
         [0085]     Generally, once the devices are adhered to the heat sink with the aid of the mounting fixture, the devices and heat sink are aligned with and mounted to a substrate (e.g., a PCB). In some embodiments, the device(s) and, optionally, the heat sink are attached (e.g., welded or soldered (e.g., wave soldered)) to the substrate. In some embodiments, the mounting fixture is removed after the device is attached to the substrate.  
         [0086]     In some embodiments, mounting fixtures and devices may be attached to both major surfaces of a heat sink. In some embodiments, two separate mounting fixtures may be attached to opposing major surfaces of a heat sink. In some embodiments, a single mounting fixture may be applied to the heat sink such that gaps, windows, and or cavities are present on opposing surfaces of the heat sink.  
         [0087]     Referring to  FIG. 10 , a web of mounting fixtures is illustrated. Openings  1005  are formed in substrate  1000  by, e.g., die-cutting. Substrate  1000  is cut along solid lines  1001  and  1002  to form individual mounting fixtures. Optionally, score or fold line  1010  may be formed by, e.g., scoring or perforating substrate  1000 .  
         [0088]     Referring to  FIG. 11 , mounting fixture  1160  is illustrated. Mounting fixture  1160  is folded along score line  1110  and wrapped around lower edge  1131  of heat sink  1100 . In some embodiments, the mounting fixture may be formed to wrap around a side edge of a heat sink. Mounting fixture  1160  is attached to opposing major surfaces  1112  and  1113  of heat sink by, e.g., adhesive members and/or structural restraining features.  
         [0089]     Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention.