Abstract:
An RF shield having a removable cover is disclosed. An RF shield for shielding an electronic component comprises a plurality of sidewalls and an interconnecting top wall, with the sidewalls and the top wall enclosing a cavity adapted to receive therein the electrical component to be shielded. The top wall is constructed of a first thickness and includes a frangible connection defined by at least one score line circumscribing a removable central portion. The score line has a second thickness less than the first thickness. The frangible connection may be severed in response to the application of a force on the central portion, thereby permitting removal of the central portion to form an access opening.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a Radio Frequency (RF) shield having a removable cover. 
     BACKGROUND OF THE INVENTION 
     In electronic device, selected components need to be shielded from RF interference (RF interference) in order to function properly. A Radio Frequency shield (RF shield) is a protective cover frequently installed in a device over a selected one of the electronic components in order to shield that electronic component from the interfering effects of RF produced by other components in the device. A typical RF shield may be constructed of metal and includes a plurality of sidewalls and an interconnecting top wall defining a generally five-sided enclosure or cavity. The cavity is sized to receive therein the selected electronic component, which is typically mounted on a substrate. 
     Unfortunately, the shielded electronic component may require maintenance during its service life, or the component may need to be completely replaced in the event of a total failure. In such circumstances, it is desirable to have access to the electronic component without having to completely remove the shield from the substrate. Consequently, RF shields having openable lids or removable covers have been developed. The design and operation of such RF shields varies greatly, with each design having its disadvantages. 
     Accordingly, there exists a continuing need for an improved RF shield having a removable cover in order to provide access to the electronic component shielded therewithin. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention an RF shield for shielding an electronic component comprises a plurality of sidewalls and an interconnecting top wall, with the sidewalls and the top wall enclosing a cavity adapted to receive therein the electrical component to be shielded. The top wall is constructed of a first thickness and includes a frangible connection generally circumscribing and defining a removable central portion. The frangible connection is defined in part by a plurality of score lines, with each of the score lines having a second thickness less than the first thickness. The frangible connection is severable in response to the application of a force on the central portion, thereby permitting removal of the central portion to form an access opening. 
     The central portion preferably includes one or more upwardly deflected corner portions defining a tool insertion aperture. Each of the corner portions may be defined by a pair of the score lines intersecting at a vertex. Further, each of the pair of score lines preferably includes an end portion disposed adjacent to the vertex, with each end portion penetrating fully through the first thickness. 
     A replacement cover or “on-sert” is preferably provided to cover the access opening. The top wall includes a plurality of outer edge portions, with each of the outer edge portions being defined in part by an adjacent one of the score lines. The replacement cover is adapted to engage the outer edge portions to thereby secure the replacement cover over the access opening. 
     In accordance with another aspect of the invention, an RF shield is adapted for connection to a substrate, and comprises a plurality of sidewalls and an interconnecting top wall. The sidewalls and the top wall, along with the substrate, form a cavity sized to receive therein an electrical component to be shielded. The top wall has a first thickness and includes a frangible connection generally circumscribing and defining a removable central portion. The frangible connection is defined in part by a plurality of score lines, with each of the score lines having a second thickness less than the first thickness. At least one upwardly deflected portion is formed in the central portion, with the upwardly deflected portion being defined in part by a score line extending fully through the first thickness. The frangible connection may be severed in response to the application of an upward force, such as a prying force, on the central portion, which thereby permits removal of the central portion to form an access opening. 
     In accordance with yet another aspect of the invention, an RF shield comprises a plurality of sidewalls and an interconnecting top wall, with the sidewalls and the top wall forming a cavity sized to receive therein an electrical component to be shielded. The top wall is constructed of a first thickness and includes a frangible connection generally circumscribing a removable central portion. The frangible connection is defined in part by a plurality of shear lines, with each of the shear lines having a second thickness less than the first thickness. A tool insertion aperture is formed in the central portion, with the tool insertion aperture being defined in part by a score line penetrating fully through the first thickness. The tool insertion aperture is defined in part by an upwardly deflected portion formed in the central portion. The frangible connection and the tool insertion aperture thereby permit the separation of the central portion from the top wall to form an access opening upon the application of an upward prying force caused by a tool inserted into the tool insertion aperture. 
     According to still another aspect of the invention, an RF shield comprises a sidewall and an interconnecting planar top wall. The sidewall and the top wall form a cavity sized to receive therein an electrical component to be shielded. The top wall has a first thickness and includes a removable central portion being circumscribed by a line of separation. The line of separation is defined by a shear line having a second thickness less than the first thickness. Accordingly, the central portion is removable along the line of separation by applying a prying force, thereby creating an access opening. 
     These and other advantages and features of the invention will become readily apparent to those skilled in the art upon a reading of the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the course of the following detailed description, reference will be made to the attached drawings wherein like reference numerals identify like parts and wherein: 
     FIG. 1 is a perspective view of an RF shield constructed in accordance with the teachings of the present invention; 
     FIG. 2 is a perspective view similar to FIG.  1  and showing the removable cover being removed using a tool such as a screwdriver; 
     FIG. 3 is a perspective view similar to FIG. 2 but showing a portion of the top wall removed to reveal an access opening; 
     FIG. 4 is an elevational view of the RF shield shown in FIGS. 1 and 2; 
     FIG. 5 is a plan view of the RF shield shown in FIGS. 1,  2  and  4 ; 
     FIG. 6 is an enlarged fragmentary view taken along lines  6 — 6  of FIG. 5 showing a portion of the frangible connection surrounding the removable cover; 
     FIG. 7 is a perspective view of a replacement cover constructed in accordance with the teachings of the present invention which is adapted to replace the removable central portion of the top wall; 
     FIG. 8 is a cross-sectional view of the replacement cover shown installed over the access opening; and 
     FIG. 9 is a perspective view of an RF shield shown being installed over a selected electronic component on an electronic device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The embodiment described herein is not intended to limit the scope of the invention to the precise form disclosed. The embodiment has been chosen and described in order to explain the principles of the invention and its practical use in order to enable others skilled in the art to follow its teachings. 
     Referring now to the drawings, an RF shield constructed in accordance with the teachings of the present invention is generally referred to by the reference numeral  10 . The RF shield  10  is preferably constructed of metal, such as Cold Rolled Steel, Nickel Silver, or from other suitable materials as would be known to those of skill in the art. The RF shield  10  includes four sidewalls  12 ,  14 ,  16  and  18 , and also includes an interconnecting top wall  20 . The sidewalls  12 ,  14 ,  16  and  18 , along with the top wall  20  generally define an enclosure or cavity  22 . As can be seen in FIG. 9, when the RF shield  10  is positioned as shown over a selected electronic component  24  attached to a conventional printed circuit board or substrate  26 , the cavity  22  faces in a generally downward direction, so as to enable the RF shield  10  to cover the electronic component  24  in a conventional manner. Although the RF shield  10  is shown as being substantially rectangular in shape, it will be understood that other shapes may be employed. 
     Each of the sidewalls  12 ,  14 ,  16  and  18  preferably flares outwardly to form a peripheral flange  28 . Additionally, one or more of the sidewalls  12 ,  14 ,  16  or  18  may include one or more mounting projections  30  to facilitate attachment of the RF shield  10  to the substrate  26 . 
     Referring now to FIGS. 1 through 6, the top wall  20  includes a central removable portion  32  which is surrounded and generally defined by a plurality of score lines  33   a ,  33   b ,  33   c , and  33   d , which combine to form a frangible connection  34 . As shown in FIG. 6 using the score line  33   a  as an example, each of the score lines  33   a ,  33   b ,  33   c , and  33   d  of the frangible connection  34  will have a thickness that is less than the thickness of the sidewalls  12 ,  14 ,  16  and  18 . Preferably, the sidewalls  12 ,  14 ,  16  and  18  will have a thickness of approximately 0.010 inches or greater, while the frangible connection  34  created by the score lines  33   a ,  33   b ,  33   c  and  33   d  will have a thickness in the range of approximately 20%-50% of the material thickness. The RF shield  10  and the frangible connection  34  may be formed by stamping, which preferably may be accomplished in a single step using a die as would be known to those of skill in the art. 
     As shown in FIG. 2, the frangible connection  34  permits removal of the removable portion  32  from the remainder of the top wall  20 , such as by applying a prying force using a tool (such as the screwdriver shown) or even a fingernail. As can be seen in FIG. 3, an access opening  36  is created upon removal of the removable portion  32 , thus permitting access to the electronic component  24 . Further, although FIG. 2 shows the removable portion being removed in a generally upward direction, it will be understood that the removable portion  32  also may be removed by pushing the removable portion  32  into the cavity  22  and then subsequently removing it therefrom. 
     The removable central portion  32  includes four corners  38 ,  40 ,  42  and  44 , each of which is preferably angled, canted, or otherwise deflected slightly upwardly away from the planar top surface of the central portion  32 . Each of the corners  38 ,  40 ,  42  and  44  is substantially identical, and thus for purposes of brevity only the details of a single corner  38  will be described in detail. The corner  38  is generally defined by the intersecting score lines  33   a  and  33   d . The score lines  33   a  and  33   d  each include an end portion  46 ,  48 , respectively, which end portions  46 ,  48  extend fully through the thickness of the top wall  20  of the RF shield  10 . The inner extent of the corner portion  38  is defined by an angled crease  50 , which permits the corner  38  to be deflected upwardly such that a tool insertion aperture  51  is formed. The end portions  46 ,  48  of the score lines  33   a ,  33   d , respectively converge at a vertex  54 . The corner  38  may also include a perforation  52  at the vertex  54 . A plurality of other perforations  56  may also be provided in order to dissipate heat from the electronic component  24  and to improve the life of the tooling used to manufacture the RF shield  10 . 
     Referring now to FIG. 3, the RF shield  10  is shown with the removable central portion  32  removed to create the access opening  36  as explained above. The top wall  20  includes a plurality of outer edge portions  58 ,  60 ,  62  and  64  which remain after removal of the removable portion  32 . Each outer edge portion  58 ,  60 ,  62  and  64  is bounded on its inward edge by an adjacent one of the (now severed) score lines  33   a ,  33   b ,  33   c  and  33   d , respectively. Upon removal of the removable portion  32  to create the access opening  36 , access to be the electronic component housed within the cavity  22  is possible for purposes of servicing or replacing the electronic component  24 . 
     As shown in FIGS. 7 and 8, subsequent to the servicing or repair of the electronic component  24 , it may again be desirable to fully shield the electronic component  24  from the interfering effects of RF. Accordingly, a replacement cover  66  is preferably provided. The replacement cover  66  includes a plurality of side edges  68 ,  70 ,  72  and  74 , and is sized to cover the access opening  36 . Each edge  68 ,  70 ,  72  and  74  includes one or more latches  76 , each of which is adapted to engage an adjacent one of the outer edges  58 ,  60 ,  62  and  64  of the RF shield  10 , which edges can be viewed in FIG.  3 . Alternatively, the replacement cover  66  may be soldered in place, or a user may cover the opening using grounding tape or other sealing methods as desired. The replacement cover  66  preferably includes at least one upwardly deflected corner  78 , which permits removal of the replacement cover  66  in a manner similar to the removal of the removable portion  32  as has been explained above. 
     In operation, the RF shield  10  is manufactured according to conventional practices by stamping the RF shield  10  from a piece of metal stock using a die (not shown). After assembly of one ore more electronic components  24  on a substrate  26  using conventional practices, the RF shield  10  is placed over a selected component  24  such the component  24  is received within the cavity  22  of the RF shield  10 . The mounting projections  30  may be used to secure the RF shield  10  to the substrate  26  in a conventional manner. 
     Subsequently, should the electronic component  24  require servicing or replacement during its service life, the removable portion  32  can be separated from the RF shield  10  in a manner similar to that shown in FIG. 2 in order to create the access opening  36 . A tool (such as the screwdriver shown or any other suitable tool) is inserted into the tool insertion aperture  51  at any one of the four corners  38 ,  40 ,  42  and  44 . As shown in FIG. 2, the tool is being inserted under the corner  38 . By virtue of the score lines  33   a  and  33   d  intersecting at the vertex  54  of the corner  38 , and by virtue of the end portions  46  and  48  which extend fully through the material, the metal in the frangible connection  34  is easily sheared upon the application of a prying force. As the score lines  33   a  and  33   d  are severed, continued application of force causes the score lines  33   b  and  33   c  to likewise be severed until the removable portion  32  is no longer attached to the RF shield  10 . The electronic component  24  is now accessible through the access opening  36 . 
     Subsequent to servicing or replacing the electronic component  24 , the component  24  may again be shielded by installing the replacement cover  66  over the access opening  36 . The replacement cover  66  is secured over the opening  36  by pushing in a generally downward direction so that the latches  76  on each of the side edges  68 ,  70 ,  72  and  74  engage an adjacent one of the outer edges  58 ,  60 ,  62  and  64  of the RF shield  10 . The upwardly deflected corner  78  permits subsequent removal of the replacement cover  66  as outlined above. 
     Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.