Abstract:
An improved heat sink apparatus for use with an electronic component comprises a base portion and a securing portion. The base portion and the securing portion are of unitary construction. The securing portion is configured to flex about an axis to effect an engaged relation with the base portion at a locus distal from the axis. The base portion and the securing portion cooperate in the engaged relation to substantially fixedly maintain the electronic component in abutting relation with the base portion.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to heat sink assemblies. In particular, the present invention is directed to heat sink assemblies configured to provide attachment thereto of electronic components without requiring additional parts. Heretofore, attachment of electronic components with heat sinks has been accomplished in several ways. For example, a J-clip structure has been employed wherein a J-shaped clip is oriented to clampingly engage the electronic component against the heat sink using a tapped screw or a bolt-and-nut fastener to apply clamping force to effect the engagement. Supplying clamping force to engage an electrical component with a heat sink base has also been known to be effected using adhesives or spring clips. 
     Additional operations and associated extra assembly time required for such prior art engagement arrangements contribute to the cost of producing products employing such structures. Moreover, the additional pieces involved in some attachment arrangements provide opportunities for product failure by such events as parts working loose, and dropped or worked-loose parts falling within products. Such loose parts failures may occur either during assembly or during use to cause short-circuit failure by the product. Other clamping structures, such as those using self-tapping screws, may also be problematic; metal particles created by the tapping operation may cause short circuit failure of a product. 
     Cost of materials is another negative aspect of previous heat sink mounting arrangements. Additional parts, such as screws, washers, bolts, nuts and clips are additional material costs of products employing such heat sink constructions. 
     There is a need for a heat sink apparatus that facilitates cost-effective assembly of power components for products using cost-effective materials, fewer assembly steps, and less opportunity for misplaced attachment parts to cause short circuit failure of the product. 
     SUMMARY OF THE INVENTION 
     An improved heat sink apparatus for use with an electronic component comprises a base portion and a securing portion. The base portion and the securing portion are of unitary construction. The securing portion is configured to flex about an axis to effect an engaged relation with the base portion at a locus distal from the axis. The base portion and the securing portion cooperate in the engaged relation to substantially fixedly maintain the electronic component in abutting relation with the base portion. 
     The preferred embodiment of the present invention contemplates a one-time assembly operation. As a consequence of such an intended employment, certain advantageous cost-effective material choices may be made. 
     The unitary construction for a heat sink apparatus according to the present invention avoids the necessity for additional assembly parts such as screws, nuts, bolts, washers, clips and adhesives. The heat sink apparatus of the present invention also avoids the requirement for such expensive materials as spring steel suitable for repeated flexing action to accommodate repeated installations. In such one-time installation, sufficient clamping force may be applied and maintained by cold rolled steel. Cold rolled steel is significantly less expensive than the spring steel that has been used for clip structures designed to accommodate repeated installations in prior heat sink clamping arrangements. 
     It is, therefore, an object of the present invention to provide an improved heat sink apparatus that is of unitary construction using cost-effective materials. 
     It is a further object of the present invention to provide an improved heat sink apparatus that may be assembled with an associated electronic component without requiring additional hardware that may be misplaced and cause short circuit failure of a product. 
     It is yet a further object of the present invention to provide an improved heat sink apparatus that may be assembled with an associated electronic component without unnecessary assembly steps, such as ancillary process operations like drilling or tapping apertures. 
     Further objects and features of the present invention will be apparent from the following specification and claims when considered in connection with the accompanying drawings, in which like elements are labeled using like reference numerals in the various figures, illustrating the preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective drawing illustrating an example of a prior art construction of a heat sink assembled with an electronic component. 
     FIG. 2 is a perspective drawing illustrating another example of a prior art construction of a heat sink assembled with an electronic component. 
     FIG. 3 is a perspective drawing of a front view of an embodiment of the present invention before assembly with an electronic component. 
     FIG. 4 is a perspective drawing of a front view of the embodiment of the present invention illustrated in FIG. 3 after assembly with electronic components. 
     FIG. 5 is a perspective drawing of a rear view of the embodiment of the present invention illustrated in FIG. 3 after assembly with an electronic component. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a perspective drawing illustrating an example of a prior art construction of a heat sink assembled with an electronic component. In FIG. 1, a heat sink-component assembly  10  includes a heat sink base member  12 , a J-clamp  14 , a threaded fastener  16 , a lock washer  18 , and an electronic component  20 . Threaded fastener  16  and lock washer  18  may be an assembled unit. A pad  22  may be inserted intermediate electronic component  20  and heat sink base member  12 . In some product applications it is desirable to enhance thermal conductivity between electronic component  20  and heat sink base member  12 . In such products, pad  22  is preferably a “Grafoil” pad that is configured to reduce contact thermal resistance caused by surface roughness, yet is electronically conductive, to facilitate heat transfer between electronic component  20  and heat sink base member  12 . In other product applications it may be desirable to electrically isolate electronic component  20  from heat sink base member  12 . In such other products, pad  22  may be an electrically insulating pad situated intermediate electronic component  20  and heat sink base member  12 . Electrically insulating pad  22  is preferably also thermally conductive to facilitate heat transfer between electronic component  20  and heat sink base member  12 . Either embodiment of pad  22  may be adhesively attached to electronic component  20 , or to heat sink base member  12  or to both. Alternatively, threaded fastener  16  may clampingly engage pad  22  between electronic component  20  and heat sink base member  12 . 
     Heat sink base member  12  is preferably constructed of aluminum to provide good heat transfer characteristics at a moderate price. Heat sink base member also includes a plurality of contact members  24 ,  26 ,  28  configured for insertion into apertures in a printed wiring board for attachment within a product, as by soldering or adhesive, for example. To facilitate soldering attachment, contact members  24 ,  26 ,  28  are preferably constructed of solderable material, such as brass or steel with tin-plating. Accordingly, contact members  24 ,  26 ,  28  are attached with heat sink base member  12 ; such attachment may be effected by any convenient reliable attachment means, such as riveting, staking, pressing, adhesive or the like. In heat sink-component assembly  10 , attachment is effected by swaging buttons inserted within apertures on contact members  24 ,  26 ,  28 . Such attachment is illustrated in FIG. 1 where buttons  30 ,  32  are inserted within apertures  34 ,  36  in contact member  24 , and swaged to effect unitary connection between contact member  24  and heat sink base member  12 . 
     J-clamp  14  rests an edge  38  in abutting relation against heat sink base member  12 , and rests a face  40  in abutting relation against electronic component  20 . Electronic component  20  is configured in a manner familiar to those skilled in the art with a heat transferring metal face situated against pad  22  for effecting heat transfer to heat sink base member  12 . Threaded fastener  16  may be a self-tapping screw threadedly engaged in an aperture (not shown in FIG. 1) in heat sink base member  12 . Alternatively, threaded fastener  16  may be a bolt-and-nut fastener assembly that traverses an aperture (not shown in FIG. 1) in heat sink base member  12  to compressingly engage heat sink base member  12 , electronic component  20  and J-clamp  14 . Lock washer  18  is intended to preclude loosening of the compression fit among heat sink base member  12 , electronic component  20  and J-clamp  14 . J-clamp  14  may include a protrusion  42  from face  40  to enhance rigidity of J-clamp  14  and to enhance the clamping compression relation among J-clamp  14 , electronic component  20  and heat sink base member  12 . 
     As mentioned earlier, pad  22  may be adhesively attached with heat sink base member  12  before assembly with electronic component  20 . Alternatively, pad  22  may be clampingly engaged between electronic component  20  and heat sink base member  12  by a clamping force applied by threaded fastener  16 . Thus, in prior art heat sink-component assembly  12  illustrated in FIG. 1, J-clamp  14 , threaded fastener  16  (and perhaps an associated nut, not shown in FIG.  1 ), and lock washer  18  are several loose parts involved in assembling heat sink-component assembly  12 . 
     FIG. 2 is a perspective drawing illustrating another example of a prior art construction of a heat sink assembled with an electronic component. In FIG. 2, a heat sink-component assembly  50  includes a heat sink base member  52 , a threaded fastener  54 , a lock washer  56 , an electronic component  58  and (if required) a pad  60 . Threaded fastener  54  and lock washer  56  may be an assembled unit. Pad  60  is intended to serve essentially similar purposes in the arrangement illustrated in FIG. 2, and may be installed in similar manners as pad  22  in the arrangement illustrated in FIG.  1 . In arrangements involving traversal through pad  60  by threaded fastener  54 , such the prior art arrangement illustrated in FIG. 2, an aperture may conveniently be provided in pad  60  (not visible in FIG. 2) to facilitate installation of threaded fastener  54 . In the interest of avoiding prolixity, pad  60  will not be further discussed here. 
     Heat sink base member  52  is preferably constructed of aluminum to provide good heat transfer characteristics at a moderate price. Heat sink base member also includes a plurality of contact members  62 ,  64 ,  66  configured for insertion into apertures in a printed wiring board for attachment within a product, as by soldering or adhesive, for example. To facilitate soldering attachment, contact members  62 ,  64 ,  66  are preferably constructed of solderable material, such as brass or steel with tin-plating. Contact members  62 ,  64 ,  66  are attached with heat sink base member  52 ; such attachment may be effected by any convenient reliable attachment means, such as riveting, staking, pressing, adhesive or the like. In heat sink-component assembly  50 , attachment is effected by swaging buttons inserted within apertures on contact members  62 ,  64 ,  66 . Such attachment is illustrated in FIG. 2 where buttons  68 ,  70 ,  72 ,  74  are inserted within apertures  76 ,  78 ,  80 ,  82  in contact members  62 ,  66 , and swaged to effect unitary connection between contact members  62 ,  66  and heat sink base member  52 . 
     Electronic component  58  is configured in a manner familiar to those skilled in the art with a heat transferring metal face situated against pad  60  for effecting heat transfer to heat sink base member  12 . Threaded fastener  54  may be a self-tapping screw threadedly engaged in an aperture (not shown in FIG. 2) in heat sink base member  52 . Alternatively, threaded fastener  54  may be a bolt-and-nut fastener assembly that traverses an aperture (not shown in FIG. 2) in heat sink base member  52  to compressingly engage heat sink base member  52  and electronic component  58 . Lock washer  56  is intended to preclude loosening of the compression fit between heat sink base member  52  and electronic component  58 . 
     As mentioned earlier, pad  60  may be adhesively attached with heat sink base member  52  before assembly with electronic component  58 . Alternatively, pad  60  is kept in position by compressive force between electronic component  58  and heat sink base member  52  applied by threaded fastener  54 . Thus, in prior art heat sink-component assembly  52  illustrated in FIG. 2, threaded fastener  54  (and perhaps an associated nut, not shown in FIG.  2 ), and lock washer  56  are loose parts involved in assembling heat sink-component assembly  52 . 
     FIG. 3 is a perspective drawing of a front view of an embodiment of the present invention before assembly with electronic components. In FIG. 3, a heat sink apparatus  90  includes a heat sink base member  92 , and a pair of clamping assemblies  94 ,  95 . Heat sink base member  92  preferably has a generally multi-planar heat-dissipating shape and is constructed of an inexpensive heat dissipating material, such as aluminum. Each clamping assembly  94 ,  95  is preferably constructed of a solderable material, such as spring steel or cold rolled steel with tin-plating. In its most preferred embodiment, heat sink apparatus  90  has clamping assemblies  94 ,  95  constructed of cold rolled steel with tin-plating so that clamping assemblies  94 ,  95  have spring characteristics sufficient to effect the preferred embodiment of the present invention for one-time assembly operation (as will be presently described in connection with FIG.  4 ). 
     In the interest of simplicity, clamping assemblies  94 ,  95  will be described referring only to clamping assembly  94 . In the preferred embodiment of the present invention, clamping assemblies  94 ,  95  are mirror images of each other. Clamping assembly  94  is attached with heat sink base member  92  by known attachment methods, such as the attachment methods described in connection with contact members associated with base members in FIGS. 1 and 2 above. Of particular importance is the integral structure of clamping assemblies  94  to include contact members  96 ,  98 . Clamping assembly  94  also includes an integrally formed clamping, or securing portion  100 . Preferably, clamping portion  100  extends substantially perpendicularly from heat sink base member  92  and includes a web structure  102 , a clamping arm  104  and a latch structure  106 . Heat sink base member  92  includes a latching aperture  108  and associated adjacent latch catches  110 . Latch catches  110  are displaced from latching aperture  108  and are preferably constructed as apertures adjacent to latching aperture  108 , yet independent of latching aperture  108 . 
     Web structure  102  is oriented about an axis  112  and is comprised of at least one web  114  and associated voids  116 . The resulting web structure  102  has less material in the vicinity of axis  112  than the remainder of clamping portion  100 . Such a lesser amount of material oriented substantially along axis  112  provides a flexible sector to clamping portion  100  facilitating flexing of clamping portion  100  substantially about axis  112  to a clamping orientation generally parallel with heat sink base member  92 . The resulting clamping orientation effects clamping of an electronic component (not shown in FIG. 3) between clamping arm  104  and heat sink base member  92 . When in a clamping orientation, latch structure  106  traverses latching aperture  108 . Latch structure  106  includes a latching lip  116 . Latching lip  116  is subjected to a bias force as it flexes against proximate edge  118  of latching aperture  108  as latch structure  106  traverses latching aperture  108 . Latching lip  116  is released from bias forces as it clears proximate edge  118  and returns to an unbiased position in latching relation with respect to proximate edge  118 . Return bias spring force applied by clamping portion  100  from its flexing at web structure  102  about axis  112  urges latching lip  116  against heat sink base member  92  to engage latching lip  116  within latch catch  110 . Stop tabs  117  are included in latch structure  106  to limit motion of latch structure  106  through latching aperture  110 . In a clamping orientation, stop tabs  117  and latching lip  116  cooperate to limit movement of latch structure  106  in directions substantially perpendicular to heat sink base member  92 . 
     Positioning tabs  120  are arrayed on clamping arm  104  in appropriate dimensional distribution to substantially laterally fix an electronic component (not shown in FIG. 3) from movement in directions perpendicular to axis  112  when heat sink apparatus  90  is in a clamping orientation with an electronic component (see FIG.  4 ). Protrusions  122  extend from clamping arm  104  toward heat sink base member  92  when clamping arm  104  is in a clamping orientation. Protrusions  122  enhance the clamping force applied by clamping arm  104  upon an assembled electronic component between clamping arm  104  and heat sink base member  92 . Protrusions  122  also provide a contributing return bias pressure to seat latching lip  116  within latch catch  110 . Properly proportioning the distance protrusions  122  extend from clamping arm  104 , and the distances between axis  112  and electronic component  126  provides a leverage force applied by clamping arm  104  with protrusions  122  as a fulcrum upon an assembled electronic component to urge latching lip  116  to seat within latch catch  110 . A ridge  124  is included in clamping arm  104  to stiffen clamping arm  104 . Ridge  124  preferably extends away from heat sink base member  92  when clamping arm  104  is in a clamping orientation substantially parallel with heat sink base member  92 . An alternate embodiment, not shown, contemplates establishing ridge  124  to extend toward heat sink base member  92  when clamping arm  104  is in a clamping orientation substantially parallel with heat sink base member  92 . Such an alternate construction of clamping arm  104  employs ridge  120  in “double duty” as a stiffener as well as in enhancing clamping action with an assembled electronic component. In such an alternate construction, protrusions  122  could be eliminated. 
     FIG. 4 is a perspective drawing of a front view of the embodiment of the present invention illustrated in FIG. 3 after assembly with electronic components. In FIG. 4, heat sink apparatus  90  is assembled with an electronic component  126  clampingly engaged between clamping arm  104  and heat sink base member  92 . A pad  128  may be installed between electronic component  126  and heat sink base member  92 . Pad  128  is optional; it may be employed in connection with heat sink apparatus  90  to enhance heat transfer between electronic component  126  and heat sink base member  92 . Pad  128  may be electrically insulating if required by the product employing heat sink apparatus  90 . Pad  128  is substantially similar in its configuration, construction, installation and employment as pad  22  (FIG. 1) and pad  60  (FIG.  2 ). In order to avoid prolixity, pad  128  will not be further discussed here. 
     In the assembled orientation of heat sink assembly  90  and electronic component  126  illustrated in FIG. 4, clamping portion  100  has been flexed at web structure  102  about axis  112  to orient clamping arm  104  generally parallel with heat sink base member  92 . Latch structure  106  has traversed latching aperture  108  and latching lip  116  has reflexed substantially to its position before flexing against proximate edge  118  while traversing latching aperture  108  and engaged in latch catch  110 . Preferably, latch catch  110  has a chamfered edge to facilitate catching (not visible in FIG.  4 ). Stop tabs  117  limit motion of latch structure  106  through latching aperture  110 . In a clamping orientation, stop tabs  117  and latching lip  116  cooperate to limit movement of latch structure  106  in directions substantially perpendicular to heat sink base member  92 . 
     Protrusions  122  bear against electronic component  126  to enhance clamping engagement among clamping arm  104 , electronic component  126  and heat sink base member  92 . Protrusions  122  also contribute a return bias force applied to clamping arm  104  to seat latching lip  116  within latch catch  110  by a levering action using protrusions  122  as fulcrums against electronic component  126 . Tabs  120  are located adjacent electronic component  126  to substantially fix electronic component  126  against movement in directions perpendicular to axis  112 . 
     FIG. 5 is a perspective drawing of a rear view of the embodiment of the present invention illustrated in FIG. 3 after assembly with an electronic component. In FIG. 5, heat sink apparatus  90  is assembled with electronic component  126  clampingly engaged between clamping arm  104  (FIG. 3) and heat sink base member  92 . Latch structure  106  has traversed latching aperture  108 , and latching lip  116  has reflexed after traversing proximate edge  118  to latchingly engage latch catch  110 . Stop tabs  117  bear against heat sink base member  92  to cooperate with latching lip  116  to limit movement of latch structure  106  in directions perpendicular to heat sink base member  92 . 
     Also visible in FIG. 5 is the preferred structure for attaching clamping assembly  94  with heat sink base member  92 . Buttons  130 , preferably integrally formed of heat sink base member  92 , are situated within apertures  132  and swaged or otherwise deformed to firmly affix clamping assembly  94  and heat sink base member  92  into a unitary assembly. 
     FIGS. 3 through 5 illustrate the preferred embodiment of the present invention configured for compressive latching assembly of heat sink base member  92  with a plurality of electronic components  126 . Other embodiments of the present invention are useful as well: a single-unit assembly for engaging a single electronic component is illustrated in FIG. 4 by dividing heat sink assembly  90  in two assemblies along a dividing axis  140 . Such a single-component construction is within the scope of the present invention. It is also within the scope of the present invention for clamping arm  104  to span more than one electronic component  126  in a clamping orientation. In such a multi-component spanning design, protrusions  122  (or, in the alternative, ridge  124  reversed) would be carefully designed in their protruding distance in order to ensure proper clamping action for each respective electronic component  126  spanned, as well as to ensure proper leveraging action to contribute return bias force to clamping arm  104 . It may be required that respective protrusions  122  associated with different electronic components  126  must extend differing distances in such multi-component spanning arrangements to properly contribute appropriate clamping forces and return bias forces. 
     It is to be understood that, while the detailed drawings and specific examples given describe preferred embodiments of the invention, they are for the purpose of illustration only, that the apparatus and method of the invention are not limited to the precise details and conditions disclosed and that various changes may be made therein without departing from the spirit of the invention which is defined by the following claims: