Patent Publication Number: US-10322921-B2

Title: One-piece board level shielding with peel-away feature

Description:
RELATED APPLICATIONS 
     This application is a divisional application of, and claims priority to, U.S. patent application Ser. No. 12/836,263 filed on Jul. 14, 2010, the entire disclosure of which is expressly incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates generally to shielding elements, and more particularly to an improved one-piece board level shielding element for electrical or electronic components of an electric or electronic circuit with a cover that can be removed for repair of the component by peeling away the top cover of the shield. 
     Related Art 
     Shielding elements are used in electric and/or electronic circuits to screen specific components of the circuit against electromagnetic radiation, in particular against spurious emission or irradiation. In particular, screening or shielding elements are used to comply with the requirements of EMC (electro magnetic compatibility) standards. 
     Usually such shielding elements have an annular side wall that can be mounted on a printed circuit board in a usual way, e.g. by soldering, and that surrounds the components to be shielded. After mounting the annular side wall and the components to be shielded onto the printed circuit board, a cover is used to close a ceiling opening that is defined by the upper edge of the annular side wall. A bottom opening that is defined by the lower edge of the side wall is closed by the substrate or printed circuit board. The terms “upper” and “lower” are used in this description to define the location of parts of the shielding element relative to the substrate irrespective of the orientation of the substrate itself. Hence, the upper edge of the side wall is that edge that is in a remote position whereas the lower edge is that edge that is in contact with the substrate after mounting. 
     As described above, mounting of a conventional shielding element onto a printed circuit board needs two mounting steps: First, mounting the side wall to the printed circuit bar and second, fixing the cover to the side wall. Often it is necessary to access the component for replacement or repair. A wide variety of methods to do this have been proposed. For example, U.S. Pat. No. 6,903,262 discloses a one-piece shielding element with notches in the planar shield cover to form a predetermined breaking line. The use of opposed V-shaped grooves is suggested in U.S. Pat. No. 6,831,224 for breakably and releasably opening the shield yet maintain a bendable hinge. U.S. Pat. No. 6,384,324 provides a shielding screen wherein the upper face has a precut line and holes to allow removal of the upper face of the shield. U.S. Pat. No. 5,614,694 provides shear lines and a hinge to allow the metallic cover to be raised and closed. 
     Costs are a driving force in the electronics industry. Typical board level shield having a two piece construction includes a shielding element composed of a shield cover or lid mounted on a side wall soldered to a circuit board surrounding the component. The side walls include holes or dimples for receiving corresponding projections or holes for engaging the walls of the lid. Such a two piece construction requires almost twice as the raw materials and processing costs of a one-piece design. 
     Notwithstanding these improvements in a variety of board level shields, there remains a need to provide yet an easy to install and less expensive way to provide access to the shielded electronic components that need to be serviced. 
     SUMMARY OF THE INVENTION 
     Generally speaking, in accordance with the invention, a one-piece board level shielding element with a top cover peel-away panel defined by a peel line secured to a circuit board to shield a component and provide access to the shielded component is provided. The shielding element is formed with a top cover having a tear-off line to facilitate removal with a peel-away tool. The original shielding element side walls remain on the circuit board. Once the component is repaired, a new replacement lid is put on to the remaining side-walls to reestablish the shielding. The side walls are provided with holes or dimples for attaching a replacement lid with corresponding dimples or holes on the replacement side walls dimensioned to fit over the remaining side walls. 
     The top is formed with a peel tool insertion slot and an adjacent peel start slot on the peel line. In order to remove the peel panel, a peel hook mounted to a cylindrical peel key is inserted into the insertion slot and hooked the shield cover at the peel start slot. Upon rotating the peel key away from the peel start slot, the peel panel is easily removed along the peel line. A fixture plate with a central opening allows the peel key to remove the peel panel without damage to the side walls. 
     Accordingly, it is an object of the invention to provide a one-piece shielding element for electric and/or electronic components of an electric and/or electronic circuit that provide access to the component after repair and assembly. 
     Another object of the invention is to provide a one-piece shielding element with a top cover formed with an improved peel panel. 
     A further object of the invention is to provide a one-piece shielding element with peel panel that readily accepts a replacement lid after removal of the peel panel. 
     Yet another object of the invention is to provide a one-piece shielding element with a top peel panel having a peel tool insertion slot and peel start slot. 
     Still another object of the invention is to provide a peel tool for removing the peel panel of a shielding element. 
     Yet a further object of the invention is to provide a fixture plate for use with a peel tool for moving the peel panel. 
     The invention accordingly comprises a product possessing the features, properties, and the relation of components and the several steps and the relation of one or more of each steps with re-respect to each of the others which will be exemplified in the product hereinafter described, and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing(s), in which: 
         FIG. 1  is a perspective view of a shielding element having a top cover with a peel line constructed and arranged in accordance with the invention; 
         FIG. 2  is a top plan view of the shielding element of  FIG. 1 ; 
         FIG. 3  is a side elevational view of one side of the shielding element of  FIGS. 1 and 2 ; 
         FIG. 4  is an exploded sectional view of the top cover of the shielding element of  FIG. 1  showing a groove of a preformed peel line; 
         FIG. 5  is an exploded sectional view of the top cover of the shielding element of  FIG. 1  showing a preformed peel line formed by a half shear method with a coining ring; 
         FIG. 6  is an exploded sectional view of the top cover of the shielding element of  FIG. 1  showing a preformed peel line formed by a half shear method using a punch and die; 
         FIG. 7  is a perspective view of a fixture plate suitable for use in removing a peel panel from a top cover of a shielding element constructed in accordance with the invention; 
         FIG. 8  is a top plan view of the fixture plate of  FIG. 6  in position on a shielding element; 
         FIG. 9  is a sectional view of the fixture plate taken along line  7 - 7  in  FIG. 6 ; 
         FIG. 10  is a perspective view of a peel tool constructed and arranged in accordance with the invention; 
         FIG. 11  is a top plan of a peel tool positioned on a fixture plate of  FIG. 6 ; in accordance with the invention; 
         FIG. 12  is a sectional view of the peel tool of  FIG. 9  inserted into the top cover for removal of the peel panel. 
         FIG. 13  is a perspective view of a replacement lid for use with the shielding element of  FIG. 1 ; 
         FIG. 14  is a partial sectional view of a portion of the replacement lid of  FIG. 13 ; and 
         FIG. 15  is a showing of a replacement lid being positioned over side walls of the shielding element of  FIG. 1  in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of a one-piece shielding element  11  for shielding an electric or electronic component on a printed circuit board. Shielding element  11  has a top cover  12  that is essentially square in this embodiment, but can be any shape, such as rectangular, triangular, and the like. Shielding element  11  has four side walls  13 ,  14 ,  16  and  17  extending at about 90° from top cover for mounting on a circuit board about the electronic component to be shielded. 
     Side walls  13 ,  14 ,  16  and  17  are each formed with a plurality of openings  18 . Side walls  13 ,  16 , and  17  are each formed with a mounting tab  19  shown in side wall  13  in  FIG. 3  for positioning shielding element  11  on a circuit board and soldering it thereto. 
     Top cover  12  is a treated to form a peel line  21  that defines a peel panel  22 . In order to facilitate removal of peel panel  22  to access the shielded component for repair, top cover  12  is also formed with a peel start slot  23  in one corner of cover  12  along peel line  21 . A peel tool insertion slot  24  is formed adjacent to peel start slot  23  in peel panel  22 . 
     Peel line  21  is formed by work hardening top cover  12  in a selected predetermined line around the perimeter of shielding element top cover  12  to form tear away zone, or peel panel  22 . Various ways are available to treat the material of top cover  12 , such as by forming a pinch edge, compressing the material, or forming a groove on the underside of cover  12 . It has been found that forming a groove having a flat at the bottom of the groove and angled side wall as shown in  FIG. 4  provides consistent results and causes less wear on the groove punch. 
     As shown in  FIG. 4 , a groove  26  is punched into the lower surface of cover  12 . Groove  26  has a trapezoidal cross-section and extends into a portion of the thickness of cover  12  between about 50-85 percent of the thickness of top cover  12 . Groove  26  ends in a flat wall  27  and two angled walls  28  and  29  at an angle α. It is desirable to maintain angle α at a minimum to reduce the volume of material displaced by the die. Preferable, angle α is maintained at less than about 30° and most preferable between about 10 and 20°. 
     Referring to  FIG. 5 , preformed peel line  21  may be formed with a coining ring  51  engaging the bottom surface of top cover  12  and a punch  52  engaging the upper surface of top cover  12  causing cover material  12  to compress. This forms a pinch edge  52   a  and a work hardened area  53  and causes top cover  12  to shear upwardly slightly at pinch edge  52   a  a distance P. Coining ring  51  may be square or have an inclined edge  51   a  and enter into cover  12  a depth H of between about 30 to 70 percent of the thickness of top cover  12 . Preferably, depth H is between about 40 to 60 percent of the thickness of top cover  12 . This work hardened section forms a groove  12   a  in the bottom surface of top cover  12 . Groove  12   a  and work hardened area  53  form peel line  21 . Distance P of pinch edge  52   a  formed on the upper surface of top cover  12  is between about 30 to 70 percent of depth H, and preferably between about 40 to 60 percent of depth H. 
       FIG. 6  shows another half shear method to form peel line  21 . A square edged die  56  engages the bottom surface of top cover  12  and a punch  57  engages the top surface of cover  12  a distance  58  from punch  57 . This forms a cut clearance of between about 5 to 20 percent of the thickness of top cover  12 , preferably between about 5-10 percent of the material thickness. This causes a shear thickness  61  of top cover  12  of between about 10 to 30 percent, and preferably between about 15 to 20 percent of the thickness of top corner. A work hardened section  59  between die  56  and punch  57  allows cover  12  to break along work hardened section  59  corresponding to peel line  21 . 
       FIG. 7  is a perspective view of a fixture plate  31  used with one-piece shielding element  11  to facilitate removal of peel panel  22 . Fixture plate  31  is complementary in size and shape to fit over shielding element  11  and has four legs  32  and an open center  33  to provide access to peel panel  22 . Open center  33  is between peel line  21  and the edges of top cover  12  at side walls  13 ,  14 ,  16  and  17 . As shown in the cross-section in  FIG. 9 , fixture panel  31  has a flange  34  that fits over and covers a portion of cover  12  outside of peel line  21 . This is shown in the plan view of  FIG. 8  with fixture plate  31  positioned on shielding element  11 . 
     In order to remove peel panel  22 , a peel tool  36  as shown in  FIGS. 10 and 12  is used. Peel tool  36  has an elongated key section  37  with a peel hook  48  at the distal end and is connected at the proximal end to a cylindrical peel key  38 . Peel key  38  is provided with holes  39  for inserting a peel pin  41  for added leverage in removing peel panel  22 . 
     In order to use peel tool  36  to remove peel panel  22  and provide access to the electrical component the following steps are followed. Peel fixture plate  31  is positioned on shielding element  11 . When properly positioned, fixture plate  31  cradles shielding element  11  and restrains the edge of cover  12  yet allows access to peel panel  22 . As shown in  FIGS. 11 and 12 , peel hook tip is inserted into insertion slot  24  and peel hook tip is positioned into peel start slot  23  with peel key  38  positioned on two walls  32  of fixture plate  31 . Pin  41  is inserted into hole  39  of peel key  38  and rotated away from peel start slot  23  in a direction shown by arrow A. Peel key  38  pushes downward on fixture plate  31  when peel key  38  is rotated in the direction of an arrow A and peeling force is applied to peel panel  22 . Peel panel  22  then easily separates from cover  12  along preformed peel line  21 . 
     Removal of peel panel  22  provides complete access to the component being shielded by shielding element  11 . Once the repairs have been completed, a replacement lid  43  as shown in  FIG. 13  can be easily installed. Replacement lid  43  includes a top cover  44  and four side walls  46  at about 90° to cover  44 . Each side wall  46  is provided with projecting nipples  47  on the inner surface to fit into holes  18  in the remaining base walls  13 ,  14 ,  16  and  17  of shielding element  11  when replacement lid  43  is positioned in a direction shown by an arrow B as shown in  FIG. 15 . This completes the repair process and provides shielding to the repaired component. 
     While the invention has been described with reference to certain preferred embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above method product without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawing(s) shall be interpreted as illustrative and not in a limiting sense. 
     The present invention may be embodied in other specific forms without departing from the spirit or essential attributes of the invention.