Abstract:
An easily openable one-piece RF interference shield and method of manufacturing the same that is cost efficient and easily adapted for use with existing electrical devices. The RF shield having a plurality of interconnected sidewalls, a substantially open bottom region, and a hingeably connected top cover portion, having a top cover latch and disposed along the top edge of one of the sidewalls. The top cover portion of the shield is adapted to hinge toward another one of the sidewalls such that the top cover latch engages a hole disposed on the other sidewall being engaged and completing a protective enclosure about electrical components and preventing those components from causing electromagnetic interferences. The RF shield of the present invention allows for easy opening of the top cover portion to provide access to the enclosure for rework or repair of the electrical components covered by the shield, without having to unsolder the unit from a substrate containing the electrical components. The plurality of sidewalls include a first mating sidewall that is connected to a first intermediate sidewall, the first intermediate sidewall being connected to a second intermediate sidewall, and the second intermediate sidewall being connected to a second mating sidewall.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to the field of electronics, and more specifically to a Radio Frequency (RF) interference shield for electrical devices. 
     BACKGROUND OF THE INVENTION 
     Over the past number of years, technological advancements in the area of electronic devices have experienced vast growth. An increase in the complexity and operation of the electrical components found in electrical devices combined with a decrease in the amount of space available for such components has resulted in dense clusters of electrical components. In such electrical devices, many electronic components radiate electromagnetic radiation which may cause interference with other electrical devices. This RF interference may detrimentally affect the performance and operation of other electrical devices. As a result, RF shields have been used to prevent such components from causing such interference. 
     The most common RF shields are comprised of a metal box contoured to fit over a PC board. These shields are then soldered onto the circuit board. Over time, the circuit board may require repair or reworking, however, it is extremely time consuming and difficult to unsolder and remove the RF shield originally in place. 
     Thus, there exists a continuing need for a low cost RF shield that will prevent electrical components of an electrical device from causing RF interference, yet will also allow fast and simple access to the electrical components covered by the RF shield. Such a shield should be easy to manufacture and be capable of adaptation to a wide array of electrical devices. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an openable one-piece RF interference shield and method of manufacturing the same that is cost efficient and easily adapted for use with existing electrical devices. The RF electrical interference shield can be mounted to circuit boards (e.g., by soldering) to prevent electrical components from causing RF interference. The RF shield of the present invention also allows for easy access to the interior of the shield for rework or repair of the electrical components covered by the shield, without having to unsolder the shield from the circuit board. 
     In accordance with one embodiment of the invention, the shield has a flat, cut out design in unassembled form. The flat, cut-out design is folded in order to create the sidewalls that define the enclosure about the electrical components to be shielded. 
     The fold lines define a series (e.g., 4) of connected sidewalls, with the two edge sidewalls each having an unconnected side edge. At one unconnected side edge of the sidewalls of the shield is a latch or tongue. At the other unconnected side edge is an opening or groove in which the latch fits or snaps to form the shield enclosure. A top cover, having its own folding lines, is a part of the one-piece shield. The top cover of the shield also includes a latch or tongue at its edge. The latch of the top cover has fold indentations on it so that the latch may bend and be inserted into an opening or slot located on the front sidewall of the shield, thereby completing the protective enclosure. The top cover may further include sidewall extensions that downwardly extend toward a bottom edge of the shield to complete the protective enclosure. 
     Once the flaps of the unassembled shield are properly folded along the fold indentations, the shield includes a plurality of sidewalls and a top cover. The RF shield does not include a bottom portion. The open bottom is necessary, otherwise the shield would cover and make inaccessible the components underneath. Instead, the open bottom combined with the plurality of sidewalls and top cover form a cavity in which the electrical components being shielded may be accessed for rework or repair. The edge sidewalls of the shield engage each other to define the protective enclosure by use of a tongue or latch on one edge sidewall designed to fit or snap into the slot or groove located on the outer edge of another sidewall. The tongue of one sidewall may be bent over and around the opening of the other sidewall to secure the enclosure. In an alternative embodiment, the groove may instead be an opening cut out of the sidewall and the tongue on one sidewall fits into the opening to secure the enclosure. The bottom edges of the sidewalls of the shield are then attached to the circuit board (e.g., by soldering), and the top cover is closed. 
     The openable top cover forms the top side of the RF shield and completes the protective enclosure once it is closed. Placing the top cover into the closed position involves bending the top cover at the fold indentations, and bending the top cover sidewall flaps at their corresponding fold lines, so that the cover rests over the cavity formed by the sidewalls. The tongue or latch extending from the top cover is externally situated with respect to the protective enclosure. The latch is bent such that the latch is situated over and around the front sidewall and is inserted through the hole or slot of the front sidewall, so that the end of the latch sits within the protective enclosure, thereby engaging the top cover to the sidewalls and completing the protective enclosure. 
     In an alternative embodiment the top cover latch may be internally situated with respect to the defined protective enclosure. That is, the top cover latch is bent such that the latch is situated inside the enclosure and extends out through the first mating sidewall hole so that the end of the top cover latch sits outside the protective enclosure. Such an alternative embodiment requires a different dimensioning of the unassembled RF shield than the previously discussed embodiment. Specifically, the top cover, up to the point where the top cover latch is disposed, must be slightly shorter in length than the previously discussed embodiment in order to allow the top cover latch to bend into the interior of the enclosure and be inserted through the first mating sidewall hole. The top cover latch is downwardly angled into the enclosure defined by the plurality of sidewalls. Positioning the top cover latch within the defined enclosure at an angle is necessary so that the latch is easier to deflect and the top cover is easier to remove. In addition, the angled latch allows an extraction tool to be easily inserted into the enclosure through an opening that is created once the latch is bent into the defined enclosure. The opening is situated between the first mating sidewall and the first bending point of the top cover latch when the top cover is in the closed position. To disengage the latch from the first mating sidewall hole, an extraction tool is slid into the opening and onto the top cover latch, thereby applying a downward force to the latch and causing it to disengage from the first mating sidewall hole. Positioning the latch perpendicularly relative to the first mating sidewall hole makes the top cover latch difficult to sufficiently deflect to remove it from the retaining hole. 
     The RF shield may be manufactured using a stamping process. The desired shape is cut out of a single sheet of metal or other material utilizing a stamping process. The stamped shape forms a central surface having a top edge and a bottom edge, a plurality of side flaps extending on opposite sides of the central surface, and one flap extending from the top edge of the central surface having a latch. The stamping process also cuts out the holes, latches and slots disposed on the plurality of sidewalls and also bends the sidewalls. After the side flaps are bent to form the plurality of sidewalls defining the enclosure, the bottom edge may then be attached to a substrate using conventional soldering methods or conventional clips or fasteners. 
     Optionally, the RF shield may be formed using plastic molding processes such as injection, or other known processes and the formed shield can then be metalized by known conventional methods. Metalizing the surfaces of the RF shield is necessary so that the shield is able to prevent the electrical components within the defined enclosure from causing electromagnetic interference outside the enclosure. In the injection molding process, heated plastic is injected into a mold that is allowed to cool, thereby hardening the plastic within the mold to the shape of the desired shield. The hardened plastic is removed from the mold and the RF shield is formed. The rotational molding process similarly begins with a mold of the RF shield. The mold is placed into a molding machine and pre-measured plastic resin is loaded into the mold. The mold is then slowly rotated on both the vertical and horizontal axes causing the plastic resin to stick to the mold and then a cooling period occurs wherein the mold continues rotating so that an even wall thickness throughout the shield is obtained. Rotational molding provides the RF shield with a consistent wall thickness and strong corners that are virtually stress free. Furthermore, a plastic formed RF shield is lighter in weight than a similarly shaped metal shield. 
     In the plastic molded shield, the plurality of sidewalls are molded as a three-dimensional unit having an open bottom and a top cover that is connected to the sidewalls via a living hinge. The top cover portion is molded to include a latch which allows the top cover to engage a hole or slot disposed on the plurality of sidewalls. The entire unit is then metalized. Once the RF shield has been metalized it is then attached to a substrate utilizing conventional soldering methods or conventional clips or fasteners. 
     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 detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings of illustrative embodiments of the invention in which: 
         FIG. 1  illustrates an unassembled RF shield of the present invention; 
         FIG. 2  is a perspective view of an RF shield constructed in accordance with the present invention; 
         FIG. 3  is a cross-sectional view taken along lines A—A of the RF shield shown in  FIG. 2 ; 
         FIG. 4  illustrates an alternative design of an assembled RF shield; 
         FIG. 5  is a cross-sectional view of the alternative design of  FIG. 4  taken along lines B—B of the RF shield shown in  FIG. 4 ; 
         FIG. 6  illustrates an alternative design of the unassembled RF shield; 
         FIG. 7  is a perspective view of the alternative design of the RF shield shown in  FIG. 6 ; 
         FIG. 8  illustrates an alternative design of the unassembled RF shield; 
         FIG. 9  is a perspective view of the alternative design of the RF shield shown in  FIG. 8 ; and 
         FIG. 10  is a perspective view of a molded RF shield constructed in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, the present invention is directed to an openable one-piece RF interference shield illustrated generally, in unassembled form, at  2  in  FIG. 1 .  FIG. 2  illustrates, in perspective view, the unassembled RF shield  2  of  FIG. 1  in assembled form, wherein a top cover  4  has been fitted to a first mating sidewall  6 . Disengaging the top cover  4  from the first mating sidewall  6  allows for easy access to the interior of the RF shield  2  for rework or repair of the electrical components covered by the shield, without having to unsolder the base of the RF shield  2  from the circuit board. 
     In accordance with one embodiment of the invention, the RF shield  2  has a flat, cut out design in unassembled form illustrated in  FIG. 1 . The unassembled form of the RF shield  2  is folded at lines  22 ,  24 ,  26 , and  28  as well as other broken line indications. To a design indicated in  FIG. 2 , lines  22 ,  24 ,  26 , and  28  establish where the unassembled shield unit is to be folded. 
     Referring to  FIGS. 1 and 2 , the RF shield  2  includes a first mating sidewall  6 , a second mating sidewall  8 , a first intermediate sidewall  10 , a second intermediate sidewall  12 , and a top cover  4 .  FIGS. 1 and 2  show the top cover  4  connected to the second intermediate sidewall  12  with a top cover latch  14  engaging a first mating sidewall hole  20  to complete the protective enclosure. However, the top cover  4  can be connected to any of the other sidewalls of the shield so long as a hole or slot is disposed on a sidewall opposing the sidewall connected to the top cover  4  to provide a point of engagement for the top cover latch  14  when the shield is closed to complete the protective enclosure. The first mating sidewall  6  is at one of the unconnected side edges of the shield and is connected to the first intermediate sidewall  10  at fold line  22  and includes a first mating sidewall latch  16  and a first mating sidewall hole  20 . The second mating sidewall  8  is at the other unconnected side edge and is connected to the second intermediate sidewall  12  at fold line  26  and includes a second mating sidewall hole  18 . The RF shield  2  is folded along the fold lines  22 ,  24 , and  26 , creating a box-like structure with a plurality of sidewalls which define the protective enclosure. The plurality of sidewalls are secured together by engaging the first mating sidewall latch  16  with the second mating sidewall hole  18 , thereby securing the first mating sidewall  6  to the second mating sidewall  8 . The first mating sidewall latch  16  may also thereafter be bent over and through the second mating sidewall hole  18  to further secure the connection. Since it is unnecessary to disengage the connection between the first mating sidewall  6  and the second mating sidewall  8  for rework or repair of the electrical components being shielded, the contact point between the two mating sidewalls may be soldered to provide increased rigidity for the RF shield  2 . In an alternative embodiment, the second mating sidewall hole  18  may be designed as a slot or groove that is cut out of the second mating sidewall  8  at a predetermined location. The plurality of sidewalls are then secured together by bending the first mating sidewall latch  16  through the slot or groove of the second mating sidewall  8 , thereby securing the first mating sidewall  6  to the second mating sidewall  8 . 
     The RF shield  2  further includes an open bottom with a bottom edge  34 . The open bottom is necessary, otherwise the RF shield  2  would cover and make inaccessible the electrical components underneath. Instead, the open bottom combined with the plurality of sidewalls and the top cover  4  form a cavity in which the electrical components being shielded may be accessed for rework or repair. The bottom edge  34  is the contact point between the RF shield  2  and the substrate. The bottom edge  34  of the RF shield  2  is fixed to the substrate, for example by soldering the bottom edge  34  to the substrate or fastening the bottom edge to the substrate using conventional fasteners or rivets. 
     The openable top cover  4  of the RF shield  2  completes the protective enclosure over the electrical components once the top cover  4  is placed into the closed position.  FIG. 2  illustrates the openable top cover  4  situated in the closed position. The top cover  4  is connected to the second intermediate sidewall at a fold line  28 , and includes fold lines  30  and  32  and a top cover latch  14 . Additionally, the top cover includes fold lines  29  and  33  associated with the top cover sidewall flaps  31  and  35 . As previously mentioned, the top cover  4  can alternatively be connected to any of the other sidewalls of the shield. Referring now to  FIGS. 1–3 , the placement of the top cover  4  into the closed position involves bending the top cover  4  at the fold line  28  toward the first mating sidewall  6 , and further, bending at the fold lines  30  and  32  so that the top cover  4  rests over the cavity defined by the plurality of sidewalls. The bending at fold lines  30  and  32  assist in relieving some of the stress that may eventually break the connection at fold line  28 . Alternatively, the fold lines  30  and  32  (and corresponding folding) may be omitted, for example, where repeated opening and closing of the top cover is not needed. The top cover sidewall flaps  31  and  35  are bent toward the bottom edge  34  of the RF shield  2  and allow the top cover  4  to rest on the sidewalls of the RF shield  2 . 
     As illustrated in  FIG. 3 , the top cover latch  14  is externally situated with respect to the defined protective enclosure. The top cover latch  14  includes fold lines  36 ,  38 , and  40 , shown in  FIG. 1 . The top cover latch  14  is bent at fold lines  38  and  40  so that the latch bends over and around the top of the first mating sidewall  6  and is inserted through the first mating sidewall hole  20 . The end of the top cover latch  14  sits within the defined protective enclosure, and thereby engages the top cover  4  and the plurality of sidewalls and completes the protective enclosure by locking the RF shield  2  into the closed position. 
     In an alternative embodiment, illustrated in  FIGS. 4 and 5 , the top cover latch  14  may be internally situated with respect to the defined protective enclosure. That is, the top cover latch  14  is bent at fold lines  36  and  40  so that a portion of the latch is inside the enclosure and then the latch is inserted through the first mating sidewall hole  20 . The remainder of the latch extends out through the first mating sidewall hole  20  so that the end of the top cover latch  14  sits outside the protective enclosure. The positioning of the top cover latch  14  through the first mating sidewall hole  20  locks the top cover  4  to the first mating sidewall and completes the protective enclosure. 
     An internally situated top cover latch  14  requires a different dimensioning of the unassembled RF shield  2  than the previously discussed embodiment. Specifically, the top cover  4 , up to the point where the top cover latch  14  is disposed, must be slightly shorter in length than the previously discussed embodiment in order to allow the top cover latch  14  to bend into the interior of the enclosure. The top cover latch  14  is downwardly angled into the enclosure defined by the plurality of sidewalls as a result of bending along fold line  36 . Positioning the top cover latch  14  within the defined enclosure at an angle is necessary so that the latch is easier to deflect and the top cover  4  is easier to remove. In addition, the angled latch allows an extraction tool to be easily inserted into the enclosure through an opening that is created once the latch is bent into the defined enclosure. The opening is situated between the first mating sidewall  6  and the first bending point of the top cover latch  14  (or fold line  36 ) when the top cover  4  is in the closed position. To disengage the latch from the first mating sidewall hole  20 , an extraction tool is slid into the opening and onto the top cover latch  14 , thereby applying a downward force to fold line  40  and the latch and causing it to disengage from the first mating sidewall hole  20 . Positioning the latch perpendicularly relative to the first mating sidewall hole  20  makes the top cover latch  14  difficult to sufficiently deflect to remove it from the retaining hole. 
       FIGS. 6 and 7  illustrate an alternative embodiment of the present invention wherein the RF shield  42  includes a mating top cover  44  disposed with a latch  54  and fold lines  58  and  60  and a plurality of sidewalls which define the protective enclosure. A polygonal hole is defined by lines  60 ,  62 ,  64  and  66 . The plurality of sidewalls are formed by bending the sidewalls along fold lines  60 ,  62 ,  64  and  66 , external of the polygonal hole, upward. The plurality of sidewalls include a mating or front sidewall  46  disposed with a hole  56 , left and right sidewalls  48 , and  50 , and a rear sidewall  52  which is formed when the mating top cover  44  is folded along fold line  58 . The mating top cover  44  engages the mating sidewall  46 , and thereby completes the protective enclosure, by bending the mating top cover  44  at its fold line  60  toward the open bottom region and further bending the latch  54  and inserting the latch  54  through the hole  56  of the mating sidewall  46  so that the end of the latch  54  is positioned within the protective enclosure. An open bottom region is necessary, otherwise the RF shield  2  would cover and make inaccessible the electrical components underneath. A bottom edge, that is defined by fold lines  60 ,  62 ,  64  and  66 , defines the contact edges between the RF shield  42  and the substrate. The bottom edge is fixed to the substrate, for example by soldering the bottom edge to the substrate or fastening the bottom edge to the substrate using conventional fasteners or rivets. 
       FIGS. 8 and 9  illustrate another alternative embodiment of the present invention wherein the RF shield  72  includes a mating top cover  74 , disposed with a hole  76  and fold line  82 , which engages a mating sidewall  78  disposed with a latch  80 . A plurality of sidewalls are formed by bending the mating sidewall  78 , a left sidewall  92 , a right sidewall  96 , and a rear sidewall  94  upwards along fold lines  84 ,  86 ,  90 , and  88  respectively. The plurality of sidewalls define a protective enclosure wherein the electrical components sought to be shielded are situated. The bottom edge  100  is affixed to a substrate using conventional soldering methods or conventional clips or fasteners. The mating top cover  74  is preferably connected to the rear sidewall  94  at tab  98 . The tab  98  is bent towards the defined protective enclosure to position the mating top cover  74  over the defined enclosure. Further, the mating top cover  74  is bent along fold line  82  so that the hole  76  is positioned proximate the latch  80 . The latch  80  is bent and inserted through the hole  76  to secure the mating top cover  74  to the mating sidewall  78  and thereby completing the protective enclosure. Similarly, the mating top cover  74  is opened to reveal the defined enclosure by disengaging the latch  80  from the hole  76  and bending the mating top cover  74  at tab  98  upwards and away from the defined enclosure. Alternatively, the mating top cover  74  is disposed with the latch  80  and the mating sidewall is disposed with the hole  76 . 
     Referring again to  FIGS. 1 and 2 , the RF shield  2  may be manufactured using a stamping process. The shape illustrated in  FIG. 1  is cut out of a single sheet of metal or other material utilizing a stamping process. The stamped shape forms a central surface having a top edge and a bottom edge, a plurality of flaps extending on opposite sides of the central surface, and one flap extending from the top edge of the central surface having a latch. The stamping process creates the components of the RF shield  2  and forms the shield in one operation. 
     Referring now to  FIG. 10 , optionally, the RF shield  102  may be formed using plastic molding processes such as injection or other known processes. The formed shield can then be metalized by conventional methods. Metalizing the surfaces of the RF shield  102  is necessary so that the shield is able to prevent the electrical components within the defined enclosure from causing electromagnetic interference outside the enclosure. In the injection molding process, heated plastic is injected into a mold that is allowed to cool, thereby hardening the plastic within the mold to the shape of the desired shield. 
       FIG. 10  illustrates a perspective view of a plastic molded RF shield  102  constructed in accordance with the present invention. In the plastic molded RF shield  102 , the plurality of sidewalls are molded as a three-dimensional unit having an open bottom and a top cover  104  that is connected to the sidewalls via a living hinge  100 . The top cover portion  104  is molded to include a top cover latch  114  which allows the top cover to engage a hole  120  disposed on the first mating sidewall  106 . The entire unit is then metalized. Once the RF shield  102  has been metalized it is then attached to a substrate utilizing conventional soldering methods or conventional clips or fasteners. 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.