Abstract:
A heat-dissipating EMI/RFI shield ( 100 ) has a shield base ( 110 ), a shield cap ( 130 ), and a heat sink ( 150 ). The shield base has at least one sidewall ( 112 ) which defines an open area ( 113 ). At least one mounting leg ( 114 ) extends from the sidewall and is affixed to a printed circuit board ( 200 ). The shield cap has a collar ( 136 ) which defines an opening in the shield cap. The shield cap is configured to be mated to the shield base. The heat sink has a boss ( 156 ) extending therefrom. The heat sink is configured to be mated to the shield cap. The boss is configured to protrude at least partially into the opening in the shield cap and to make thermal contact with a selected heat generating component ( 210 ) on the printed circuit board.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority of U.S. Provisional Patent Application No. 61/752,674, filed Jan. 15, 2013, entitled “Heat-Dissipating EMI/RFI Shield,” the entire disclosure and contents of which are hereby incorporated by reference herein. 
     
    
     SUMMARY 
       [0002]    A heat-dissipating EMI/RFI shield has a shield base, a shield cap, and a heat sink. The shield base has at least one sidewall which defines an open area, and the sidewall has at least one mounting leg extending from it. The shield cap has a collar which defines an opening in the shield cap. The shield cap is configured to be mated to the shield base. The heat sink is configured to be mated to the shield cap. The heat sink has a boss extending therefrom. The boss is configured to protrude at least partially into the opening in the shield cap to make thermal contact with a heat generating component on a printed circuit board to which the heat-dissipating EMI/RFI shield is attached. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIGS. 1A and 1B  are exploded perspective diagrams showing an exemplary heat-dissipating EMI/RFI shield; 
           [0004]      FIG. 2  is a perspective diagram showing an exploded view of the heat-dissipating EMI/RFI shield of  FIG. 1 ; 
           [0005]      FIG. 3  is a perspective diagram showing the partially assembled heat-dissipating EMI/RFI shield of  FIG. 1 ; 
           [0006]      FIG. 4  is a top view perspective diagram showing an assembled heat-dissipating EMI/RFI shield of  FIG. 1 ; 
           [0007]      FIGS. 5 and 6  are bottom and top view perspective diagrams, respectively, showing another exemplary heat-dissipating EMI/RFI shield; 
           [0008]      FIG. 7  is a perspective diagram showing another exemplary heat-dissipating EMI/RFI shield; 
           [0009]      FIG. 8  is a perspective diagram showing another exemplary heat-dissipating EMI/RFI shield; and 
           [0010]      FIG. 9  is a logical flow diagram illustrating a process for manufacturing, assembling, and utilizing an exemplary heat-dissipating EMI/RFI shield. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    The following Detailed Description is directed to technologies for heat-dissipating EMI/RFI shields (HDSs). The HDSs disclosed herein are configured to be positioned proximate selected electrical circuit components to limit the transmission of energy, such as electromagnetic interference (EMI) and/or radio frequency interference (RFI) emanating from a selected component (SC). An example of an SC is a semiconductor circuit, such as but not limited to a microprocessor, an RF amplifier, a power regulation circuit, etc. In addition, the HDSs disclosed herein are configured to shield the selected components from EMI and/or RFI emanating from other sources. Further, the HDSs disclosed herein are configured to transfer and dissipate heat emanating from the selected components. Still further, the HDSs are preferably electrically grounded, which protects the SC from static electricity discharges. 
         [0012]    In the following Detailed Description references are made to the accompanying drawings that form a part hereof, and that are shown by way of illustrated embodiments or examples. Referring now to the drawings, in which like numerals represent like elements throughout the several Figures, aspects of apparatuses, systems, and methodologies for HDSs are described. 
         [0013]      FIGS. 1A and 1B  are exploded perspective diagrams showing an exemplary heat-dissipating EMI/RFI shield (herein “HDS  100 ”). The illustrated HDS  100  includes a shield base or fence  110 , a shield cap  130 , and a heat sink  150 . Engaging components or structures, such as the illustrated push pins  170 , may be used to secure the HDS  100  to a desired component or object such as, by way of example and not of limitation, the printed circuit board (PCB)  200  illustrated in  FIGS. 2-4 . 
         [0014]    The illustrated shield base  110  comprises sidewalls  112  which define a central opening area  113 , mounting legs  114 , sidewall apertures  116 , and sidewall shoulders  118 . The base shield  110  may be constructed of an electrically conductive material, such as but not limited to light-gauge steel, aluminum, copper, combinations thereof, and the like, and is preferably made of an electrically conductive material which can be soldered. The illustrated HDS  100  is configured to enclose one or more selected heat-generating, EMI/RFI generating, and/or EMI/RFI sensitive components, such as, but not limited to, SC  210 , shown in  FIGS. 2 and 3 . The illustrated shield base  110  is configured to surround the SC  210 . The shield base  110  is illustrated as a rectangle, but may be configured in any desired or convenient shape in order to be proximate to and surround the SC  210 . The mounting legs  114  mount and preferably ground the shield base  100  to the PCB  200 . 
         [0015]    The sidewall apertures  116  are configured and positioned to matingly engage components of the shield cap  130 . A plurality of sidewall apertures  116  are illustrated at each sidewall  112 . Alternative embodiments comprise a lesser or greater number of sidewall apertures  116 . Further, some alternative embodiments do not include sidewall apertures  116  at each sidewall  112 . In still other alternative embodiments the sidewall apertures  116  may not be used but, rather, other structures may be used that matingly engage components of the shield cap  130 , such as but not limited to clips, pins, springs, arms, lips, hooks, combinations thereof, and the like. 
         [0016]    The location, configuration, and dimensions of the sidewall shoulder  118  are not critical and may, if desired, be reduced to a size which will not substantially deform when the shield cap  130  and heat shield  150  are attached. The shoulder  118  is preferably sufficiently small enough that it does not substantially inhibit the inflow of hot air for soldering operations. 
         [0017]    The illustrated shield cap  130  comprises a shield top  132 , shield flanges  133  shown configured as a plurality of leafs  134 , a collar  136  defining an opening in the shield cap, and a plurality of spring fingers  138  positioned along the collar  136  perimeter. The shield cap  130  is configured to attach to the shield base  110  and, together with other components described herein, encase the SC  210 . The shield cap  130  is illustrated as a rectangle, but alternative embodiments may be configured in any shape whatsoever in order to be proximate the SC  210 . Like the shield base  110 , the shield cap  130  may be constructed of an electrically conductive material. The collar  136  is configured to receive, and the spring fingers  138  are configured to frictionally engage, a component of the heat sink  150 , as described below. 
         [0018]    The plurality of leafs  134  are configured to engage a plurality of sidewall apertures  116 . In an alternative embodiment, the shield cap  130  releasably engages the shield base  110 . In an alternative embodiment the leafs  134  may not be used; rather, other structures may be used to matingly engage components of the shield base  110 , such as but not limited to clips, pins, springs, arms, lips, hooks, combinations thereof, and the like. The illustrated HDS  100  comprises a shield base  110  and shield cap  130  that are constructed separately and assembled after the shield base  110  is soldered to the PC board  200  of  FIGS. 2-4 . In another alternative embodiment the shield base  110  and shield cap  130  may be constructed as a single unit. 
         [0019]    The illustrated heat sink  150  comprises a platform  152 , heat dissipating fins  154 , shoe or boss  156 , and apertures  158 . The heat sink  150  may be constructed of a thermally conductive material, such as but not limited to aluminum, copper, steel, combinations thereof, and the like. The platform  152  is configured to be positioned adjacent, and preferably in contact with, the shield cap  130 , with the shoe  156  inserted through the collar  136  and frictionally engaged, and preferably thermally engaged, with the spring fingers  138 . 
         [0020]    Alternative embodiments comprise a lesser or greater number of spring fingers  138 . Further, some alternative embodiments do not include spring fingers  138  along the entire perimeter of the collar  136 . In still other alternative embodiments the spring fingers  138  may not be used; rather, other structures may be used that matingly engage the shoe  156 , such as but not limited to flanges, edges, clips, pins, springs, arms, lips, hooks, metallic tape, thermal interface material (TIM) combinations thereof, and the like. The engagement of the spring fingers  138  around the shoe  150  permits shielding EMI and/or RFI at a point close to the SC  210 , and permits grounding of the heat sink  150  at a point close to the SC  210 . 
         [0021]      FIG. 2  is a perspective diagram showing an exploded view of the heat-dissipating EMI/RFI shield  100  of  FIG. 1 . Connected to the PCB  200  is an SC  210 , which may produce and emanate heat and/or EMI and/or RFI. The shield base  110  is shown surrounding the SC  210  and attached to the PCB  200 . The illustrated shield base  110  may be structurally and electrically connected to the PCB  200  by inserting the mounting legs  114  into plated through-holes  211  on the PCB  200  that are connected to a conductive layer (not shown) within the PCB  200  such as, but not limited to, a ground plane. The mounting legs  114  are thus mechanically and electrically connected to the conductive layer (not shown) in the PCB  200  during the soldering process. 
         [0022]    Engaging components, such as push pins  170 , may be used to further secure the HDS  100  to the PCB  200 , and provide a compressive fit between the heat sink  150 , shield cap  130 , shield base  110  and PCB  200 . Here the push pins  170  are inserted through the heat sink apertures  158  ( FIGS. 1A and 1B ), and proximate the shield base  110  are mounting apertures  212  in the PCB  200  ( FIG. 2 ) that are configured to receive and anchor the push pins  170 . In alternative embodiments other types of engaging structures and configurations, such as but not limited to screws, bolts, clips, pins, arms, wires, anchors, soldering, combinations thereof, and the like, may be used to further secure the HDS  100  to the PCB  200 . Accordingly, the heat sink  150  and/or PCB  200  may comprise various engaging structures and configurations. 
         [0023]    Thus,  FIGS. 1A ,  1 B, and  2  show an exemplary heat-dissipating EMI/RFI shield assembly which includes a shield base  110 , a shield cap  130  attached to the shield base  110 , and a heat sink  150  attached to the shield cap  130 . The shield base  110  is electrically connected to a conductive layer of printed circuit board  200 , and may be structurally connected to, or may be part of, an electronic device (not shown). Further, the heat sink  150  comprises a shoe  156 , and the shoe  156  is electromechanically engaged to the shield cap  130 . 
         [0024]    As best seen in  FIGS. 1B and 2 , the heat sink  150  may be mounted to the shield cap  130  by inserting the shoe  156  through the collar  136  such that the spring fingers  138  frictionally engage the shoe  156 . The snap-in ends of the push pins  170  are inserted through the PCB apertures  158 . The heat sink  150  may thereby be structurally and electrically connected, and grounded, to the shield cap  130 , shield base  110 , and PCB  200 . 
         [0025]    The illustrated shoe  156  may be configured as an inverted “U”, comprising a channel  180 , top  182  and sidewalls  184 . The SC  210  rests within the channel  180  and may be proximate to or in direct contact with the top  182  and/or sidewalls  184 . In this manner heat generated by and emanated from the SC  210  may be transferred to the heat sink  150  and dissipated from the platform  152  and/or fins  154 . Thermal interface materials (not shown) that increase thermal conductance may be applied to fill any gaps between the SC  210  and shoe  156 , including top  182  or sidewalls  184 . The channel  180  configuration allows for close tolerances between, and contact with, the SC  210 . The shoe  156  may also be configured differently as desired to obtain good thermal contact with the SC  210 . For example, if the SC  210  has a circular shape, the shoe  156  may also have a corresponding or mating circular shape. In that event, the collar  136  may also have a similar circular shape. 
         [0026]    The HDSs  100  illustrated and described herein may perform a plurality of functions. By way of example and not limitation, the HDS  100  limits the transmission of EMI and/or RFI emanating from the SC  210 . The HDS  100  may also shield the SC  210  from EMI and/or RFI emanating from other sources. Further, the HDS  100  is configured to transfer and dissipate heat emanating from the SC  210 . Preferably, when the shield base  110  is connected to a conductive layer (not shown) in the PCB  200 , the HDS  100  is thereby electrically grounded. More specifically, the HDS  100  and each of its components, the shield base  110 , the shield cap  130 , and the heat sink  150 , are likewise electrically grounded. In such a configuration the HDSs illustrated and described herein may have the structure of a Faraday cage, especially where the PCB  200  has a ground plane (not shown) and the SC  210  is between the HDS  100  and the ground plane. 
         [0027]      FIG. 3  is a perspective diagram showing the partially assembled heat-dissipating EMI/RFI shield  100  of  FIG. 1 . The shield cap  130  is shown mounted to the shield base  110 , such that the plurality of leafs  134  are engaging a respective plurality of sidewall apertures  116 . The shield cap  130  may thereby be structurally and electrically connected, and grounded, to the shield base  110  and PCB  200 . 
         [0028]      FIG. 4  is a top view perspective diagram showing an assembled heat-dissipating EMI/RFI shield  100  of  FIG. 1 . As illustrated in  FIGS. 1A-4 , the heat sink  150  is approximately the same size as the shield base  110  and the shield top  130 . 
         [0029]      FIGS. 5 and 6  are bottom and top view perspective diagrams, respectively, showing another exemplary heat-dissipating EMI/RFI shield  100 . In this alternative embodiment, the heat sink  150  is wider than the shield cap  130  and shield base  110  in two directions, that is, the platform  152  and fins  154  of the heat sink  150  overhang the shield cap  130  and shield base  110  on two sides. Although the overhang is shown as being on two opposing sides, the heat sink  150  may be wider than, and overhang, the shield cap  130  or shield base  110  in one or more directions, and any of the sides may be overhanging sides. 
         [0030]      FIG. 7  is a perspective diagram showing another exemplary heat-dissipating EMI/RFI shield  100 . In this alternative embodiment, the heat sink  150  is narrower than the shield cap  130  and shield base  110  in two directions, that is, the platform  152  and fins  154  are inset or indented from the shield cap  130  and shield base  110  on two sides. Although the indentation is shown as being on two opposing sides, the heat sink  150  may be narrower than the shield cap  130  or shield base  110  in one or more directions, and any of the sides may be inset sides. 
         [0031]      FIG. 8  is a perspective diagram showing another exemplary heat-dissipating EMI/RFI shield  150 . In this an alternative embodiment, the heat sink  150  comprises a plurality of shoes  156  ( 156 A,  156 B). The shoes  156  may be of different and various sizes, configurations and positions to further allow for close tolerances between, and contact with, their respective SCs  210  (not shown in  FIG. 8 ). 
         [0032]    Although the shield base  110 , the shield cap  130 , and the heat sink  150  have been illustrated as being generally square, this is for purposes of convenience of illustration. These components may be any other shape appropriate, desired, or convenient for a particular SC  210  and/or device including a PCB  200  such as, by way of example and not of limitation, a rectangle, a triangle, a circle, or a polygon. While a square, rectangle or polygon is generally considered as having sides, if a component or opening or area is circular, or some other continuous shape, such a component shape may be considered as having either a single side or a plurality of sides. 
         [0033]      FIG. 9  is a logical flow diagram illustrating a process for manufacturing, assembling, and utilizing an exemplary heat-dissipating EMI/RFI shield  100 . It should be appreciated that the operations described herein can be implemented as a sequence of manufacturing steps, mechanical operations, and physical processes. The implementation may vary depending on the performance and other requirements of a particular manufacturing system or electronic device in which an HDS is utilized. It should also be appreciated that more or fewer operations may be performed than shown in the Figures and described herein. These operations may also be performed in parallel, or in a different order than those described herein. 
         [0034]    The process  300  can begin with operation  302  where an appropriate manufacturing procedure is utilized to construct the HDS components; namely, the shield base  110 , shield cap  130 , heat sink  150 , and engaging components  170 . From operation  302 , the routine  300  proceeds to operation  304 , where the HDS  100  is installed into any type of electronic apparatus. As discussed herein, the HDS  100  may be installed onto a circuit board utilized in an electronic device. More particularly, the shield base  110  is installed onto the PCB  200  and then reflow-soldered to affix it to the PCB. The open area  113  of the shield base  110  and, to a lesser degree, the optional apertures  116 , allows adequate hot air flow for resoldering operations. The shield top  130  is then fitted (pressed) onto the shield base  110 . The heat sink  150  is then mounted on top of the shield top  130 , with the boss  156  protruding through the collar  136  and making thermal contact with the SC  210 . The pins  170 , or other desired fasteners, are then used to secure the heat sink  150  to the PCB  200 . The assembly  100  is therefore fully installed. The routine  300  then proceeds to operation  306 . 
         [0035]    At operation  306  the SC  210  is operational, and emits EMI and/or RFI. The HDS  100  contains the EMI and/or RFI in that the HDS  100  substantially prevents the EMI and/or RFI for emitting beyond the shield base  110  and/or shield cap  130 . Similarly, the HDS substantially prevents EMI and/or RFI emanating from other sources from affecting the SC  210 . The routine  300  proceeds to operation  308 . 
         [0036]    At operation  308 , as the SC  210  operates, it emits heat and may generate EMI/RFI. Heat from the SC  210  is transferred to the heat sink  150  and dissipated. The routine  300  then continues to operation  310 , where it ends after the SC  210  is turned off and the heat is dissipated. 
         [0037]    Based on the foregoing, it should be appreciated that heat-dissipating EMI/RFI shields have been disclosed herein. Although the subject matter presented herein has been described in language specific to systems, methodological acts, mechanical and physical operations, and manufacturing processes, it is to be understood that the concepts disclosed herein are not necessarily limited to the specific features, acts, or media described herein. Rather, the specific features, acts and mediums are disclosed as example forms. 
         [0038]    The subject matter described herein is provided by way of illustration for the purposes of teaching, suggesting, and describing, and not limiting or restricting. Combinations and alternatives to the illustrated embodiments are contemplated, described herein, and set forth in the claims. Various modifications and changes may be made to the subject matter described herein without strictly following the embodiments and applications illustrated and described, and without departing from the scope of the following claims.