Abstract:
An electronic card which includes a printed circuit board interposed between card shields having edges. Tabs on an edge of one shield engage recesses on the edge of the other shield. The jointed shields of the card provide high level of rigidity, sufficient to exceed applicable bending and torsional resistance specification. Adequate rigidity is thereby provided. Also included is an I/O connector grounded without a separate ground contact and shielded over its length. The tabs include an arcuate member having a medial oblique projection which engages a ledge of the other shield near the recess.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of application Ser. No. 08/651,352, filed May 22, 1996 now abandoned entitled &#34;PCMCIA Card&#34; which is a continuation-in-part of application Ser. No. 08/628,480 filed Apr. 5, 1996 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electronic cards and more particularly to exterior shells for such cards. 
     2. Brief Description of Prior Developments 
     Electronic cards are widely used, especially for adding capacity and/or functionality to personal computers. The Personal Computer Memory Card International Association (PCMCIA) has established standards for such cards, and has categorized them as the cards with type I, type II and type III cards. 
     Previously cards have employed cover shields latched and/or adhesively fixed to an intermediate frame and covers laser welded or ultrasonically welded together. More recent cards employ metal shields that are directly fixed together, without a frame. However, there are difficulties experienced in having such structures maintain sufficient rigidity to withstand flexing, bending and tension forces which would be expected to be placed on it in the course of ordinary use. There is, therefore, a need for an electronic card which avoids the above mentioned difficulties. 
     SUMMARY OF THE INVENTION 
     The electronic card of the invention comprises a printed circuit board interposed between card shields having edges. Tabs on the edges of one shield engage recesses on the edge of the other shield. Adequate rigidity is thereby provided. Also included is an I/O connector grounded without a separate ground contact and shielded over its length. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is further described with reference to the accompanying drawings in which: 
     FIG. 1 is an exploded perspective view of an electronic card of the present invention; 
     FIG. 2 is a perspective view of the card shown in FIG. 1; 
     FIG. 3 is an enlarged view of the area in circle III in FIG. 1; 
     FIGS. 4a-4h are schematic illustrations of various ways in which the tabs and recesses in the card illustrated in FIG. 1 may be engaged within the scope of the present invention; 
     FIGS. 5a and 5b are respectively an exploded perspective view of an I/O connector used in the card shown in FIG. 1 and its accompanying universal grounding part and the I/O connector in which its universal grounding part is engaged; 
     FIGS. 6a and 6b are respectively an exploded view of an alternate I/O connector and a view of the alternate I/O connector in which its grounding part is engaged; 
     FIG. 7 is an exploded perspective view of an alternate shielded I/O receptacle; 
     FIG. 8 is a perspective view of an alternate shield member which may be used with the I/O receptacle shown in FIG. 7; 
     FIG. 9 is an exploded perspective view of an alternate preferred embodiment of the card of the present invention; 
     FIG. 10 is a bottom perspective view of the card of FIG. 9; 
     FIG. 11 is a top perspective view of a card shield used in the card shown in FIG. 9; 
     FIG. 12 is a detailed view of the area within circle XII in FIG. 11; 
     FIG. 13 is a detailed view of the area with circle XIII in FIG. 11; 
     FIG. 14 is a detailed view of the I/O connector used in the card connector shown in FIG. 9; 
     FIG. 15 is a cross sectional view through an engaged latch; 
     FIG. 16 is a cross section through XVII--XVII in FIG. 16; and 
     FIG. 17 is a cross section through XVIII--XVIII in FIG. 16. 
     FIG. 18 is a top plan view of a shield used in another preferred embodiment of the card of the present invention; 
     FIG. 19 is a side elevational view of the shield shown in FIG. 18; 
     FIG. 20 is an end view of the shield shown in FIG. 18; 
     FIG. 21 is an end view of the entire card which makes use of the shield shown in FIG. 18; 
     FIG. 22 is a top plan view of a shield used in another preferred embodiment of the card of the present invention; 
     FIG. 23 is a side elevational view of the shield shown in FIG. 22; 
     FIG. 24 is an end view of the shield shown in FIG. 22; 
     FIG. 25 is a top plan view of a shield used in another preferred embodiment of the card of the present invention; 
     FIG. 26 is a side elevational view of the shield shown in FIG. 22; 
     FIG. 27 is an end view of the shield shown in FIG. 22; 
     FIG. 28 is a partial perspective view of the shield shown in FIG. 18; 
     FIG. 29 is an enlarged view of the area within circle XXIX in FIG. 28; 
     FIG. 30 is a blank from which the shield shown in FIG. 18 may be manufactured; 
     FIG. 31 is an enlarged view of the area within circle XXXI in FIG. 30; 
     FIG. 32a is an alternate view of a tab; and 
     FIG. 32b is an alternate view of a recess. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1-3, the PCB assembly consists of the metallized receptacle I/O connector 1 at one end and the 68 pos MTB (MICRO TRIBEAM™ receptacle connector 2 at the other end of the board. This connector 2 has the two coding keys 3 and 4 integrated to sides of the plastic housing, simultaneously an upstanding ridge 5 on the top and bottom of this housing. On each of the two coding key ends of the connector 2, top and bottom surfaces, are also located two recesses 6. The I/O receptacle is described in detail hereafter. 
     The top and bottom card shields 7 and 8 are identical stampings of sheet metal eg. stainless steel. Over a substantial length of the shield, at one side are preferably periodically spaced, i.e. at 3 mm intervals, located upstanding tabs 9, and on the other side at same locations and periodicity appropriate recesses 10. In addition, at the front side 13 of a shield are located two fixation tabs 11, while at the rear side of each shield are extension portions 12 which are perpendicularly bent to be flush with in front of the metal shield of the connector plug opening of I/O connector 1. Such a perpendicular bend results in an improved aesthetics and also prevents an opening between I/O connector and shield and prevents what is known as a &#34;smile&#34; effect of the card while allowing for proper axial positioning of the PCB assembly. 
     When the two card shield halves 7 and 8 are positioned and moved toward each other over on either side of the PCB assembly, the tabs 9 along side and fixation tabs 11 cooperate with oppositely positioned recess 10 and 6 respectively, to obtain a final card assembly 14 shown in FIG. 2. 
     Ordinarily if only one tab 9 cooperates with one properly positioned recess 10, the force to retain the card assembly structure intact (see FIG. 2), notwithstanding the mechanical flexure/tension it is subjected to during application, is low. Due, by employing a relatively large number of tabs and recesses evenly spaced over the assembly length on both sides, is sufficient rigidity of the assembly can be achieved. In general there can be and usually is a true-position mismatch-match between tabs and the recesses, due to stamping tolerances. As a result, there can be a friction-fit of the two card shields on each other and with the recesses 6 of plastic housing of MTB connector 2. These individual friction forces can be enhanced by appropriate choice of the relative dimension/shape of the tab/recess cooperating together to form the mechanical structure. For example, considering the Section A of tab 9 in FIG. 4a, frictional engagement between the tabs and recesses can result if the tab is longer than the recess, as shown in FIG. 4d, the tab is twisted (FIG. 4e) or the tab is curved (FIG. 4c). In addition, several options for latching the tab in the recess are presented in FIG. 4b and FIGS. 4g and 4c and 4h, wherein a latch 9a, either centrally located or formed on one end of the tab, by a sheared portion, latches the tab in the recess when fully mated. The objective being to withstand the mechanical forces and hold the assembly intact. Another object is to present a substantially flat metal sides of card assembly to allow appropriate contact with a ground contact of equipment slot (not shown) which the PCMCIA card needs to fit. 
     The I/O connector is shown in FIGS. 5a and 5b in which it is shown that plastic is removed at ends of the top and bottom plastic walls 20 to allow the entry from the rear (PCB side) of two metal springs with legs 21 and 22 having inwardly projecting latches 23 and 24 and ends 25 and 26. In the final assembled condition the latches 23 and 24 contact the metal shield plug connector 18 of assembled I/O plug connector while the ends 25 and 26 are pressed on metal upper and lower shields 7 and 8 to complete the total ground connection of system. These two metal spring members are connected to the ground track on the PCB at two connector ends by rivets, as in initial design. 
     Referring to FIGS. 6a-6b, another embodiment is shown in which one metal piece is inserted over for the top and bottom plastic walls of receptacle I/O connector. The advantage in this arrangement, being not only, is one part needed, but that the metal shield extends over the total length of the connector while ensuring there is no potential drop between the two ground locations situated at connector ends. In this design, the inward projecting latches 23 and 24 face the central plastic insert 13 to finally connect with mating plug I/O shield 18. The outward latches 27 of the other side of the I/O connector contact the upper and lower shields 7 and 8, while the edges 25 and 26 are located also against the edges of the card shields. 
     Referring to FIGS. 7-8, a further development of the I/O receptacle shield in combination with the substitute for ground contact 7 in initial design, is shown. Here the upper and shield portions are shown as two separate half&#39;s, each with symmetrical segments of latch retaining openings 12 facing towards each other. This design alternative is not only present a metal plate with latch retaining openings, but also present at the rear end 28 of the receptacle I/O, besides the area needed for SMT legs of terminals, a metal wall over the remaining width of the card. This feature is more clearly evident in FIG. 4 showing the rear from the PCB side view of the receptacle I/O. This rear end 28 (FIG. 8) in this design when locked above a similar wall extending from lower shield portion, then affords a means for EMC/ESD shielding between the PCB electronics circuit I/O connector on this side of the card assembly. 
     Referring to FIGS. 9-16, the PCB assembly includes the metallized receptacle I/O connector 101 at one end and the 68 pos MTB receptacle connector 102 at the other end of the board. This MTB connector 102 has the two coding keys 103 and 104 integrated to sides of the plastic housing, simultaneously an upstanding ridge 105 on the top and bottom of this housing. On each of the two coding key ends of the MTB connector 102, top and bottom surfaces, are also located on the I/O connector ends and two recesses 106. The I/O receptacle is described in detail hereafter. 
     The top and bottom card shields 107 and 108 are sheet metal e.g. stainless steel. Over a substantial length of the shield, at one side are periodically located, e.g. once every 3 mm, upstanding tabs 109, and on the other side at same locations and periodicity are appropriate recesses 110. In addition, at the front side 113 of a shield is located a fixation tab 111, and at the rear side of the shield are extension portions 112 which are perpendicularly bent to be flush with in front of the metal shield of the connector plug opening of I/O connector 101 in the final card assembly condition. Such a perpendicular bend results in an improved aesthetics of the card while allowing for proper longitudinal axial positioning of the PCB assembly. 
     When the two card shield halves 107 and 108 are positioned and moved towards each to enclose of the PCB assembly, the tabs 109 cooperate with recess 110 along side and fixation tabs 111 cooperate with oppositely positioned recess 144 on the opposite side of the top shield through slot 100., to obtain a final card assembly. 
     The periodicity of tabs and recess over the assembly length on both sides, is sufficient to ensure the desired assembly rigidity. As previously stated, there usually is a true-position miss-match between the tabs and recess, due to stamping tolerances. This arrangement, then results in at least an initial friction-fit of the two card shields on each other by reason of the side tabs 109 entering side recesses 110, and two front fixation tabs 111 passing through two 106 to enter front recess 144 of the opposite shield of plastic housing of connector 102. These individual friction forces can be enhanced by appropriate choice of the relative dimension/shape of the tab/recess cooperating together to form the mechanical structure. 
     Referring particularly to FIGS. 9-10 and 14, a further development of the I/O receptacle shield in combination with the substitute for ground contact 107 in initial design, is shown. Here the upper and shield portions are shown as two separate half&#39;s each with symmetrical segments of latch retaining openings 112 facing towards each other. This design is not only present at a metal plate with latch retaining openings, but also present at the rear end 128 of the receptacle I/O, besides the area needed for SMT legs of terminals, a metal wall over the remaining width of the card. 
     FIGS. 11 and 12 shows modified forms of securing tabs wherein the tabs 109 comprise an upstanding arcuate section 130 having opposed rigid sides 131 and chamfers 132 from which a spring latch 133 extends downwardly and outwardly. Referring particularly to FIG. 13, the recesses 110 are formed in a ledge 134. The ends of the recesses 110 have edges 135 and 136 which are angled inwardly to points 138. Referring particularly to FIGS. 15-17, the tab 133 engages the underside of ledges 134 in the recesses 110. 
     The two card shields of this embodiment are preferably made from 0.2 mm stainless steel and have a number of mechanical snap fit fasteners. After assembling the two shields to each other, these fasteners make the card surprisingly and unexpectantly rigid and stiff against bending and torsion. These fasteners also effect good electrical connection for grounding between the two card shields due to multiple contact points, and also because no intermediate load bearing surfaces are utilized the card is optimally shielded for EMI. These fasteners comprise a number of tabs 109 which engage recesses 110. It will be seen from the drawings (in parts FIGS. 15 16) that each of the tabs 109 and latch 133 are angled inwardly from the perpendicular plane, for example, by angle α (FIG. 15) to better engage the recesses 110. Each tab 109 comprises a spring section 132 integrated with a latch 133, which hooks in a latch 134 underneath the area of each recess 110. This latch 133 holds the two card shields from opening after assembly. During mating, the tab 109 will be subjected to elastic bending and torsion forces from the tip of latch 133 up both rigid sides. 
     Each tab 109 includes also two rigid sides 131 which engage with some play in both ends of the recess 110. The total number of rigid sides 131 and recess ends give the mechanical connection between the two card shields a high shear strength, which results in a high stiffness against bending and torsion. It will also be noted that the two card shields are identical and are hermaphodite, that is, each shield contains both male and female fastening elements. 
     As is shown in particular with regard to FIGS. 12-14, during mating the chamfers 132 will first touch the leading edges 135 and 136 so that they will guide the tab 109 to the end position beyond points 138 and guarantee that the latch 133 will hook underneath edge 134. The points 138 function as latches to hold the tab in position in the recess and provide an audible &#34;snap&#34; that indicates proper latching. The relative dimensions of the chamfers 132 and ledges 135 and 136 are designed to absorb manufacturing (stamping) tolerances. 
     The latch mechanism is designed in a way that there is an initial play between the latch and the ledge 134 in vertical direction, which is taken away by a second spring function of ends 137 of the ledge. As these ends have a bending angle less than 90°, these make first contact when assembling the two card shields and then these have to be pressed together a little before the latch 133 will be mated. After that the latch mechanism has no further play. 
     Preferably the overall cumulative lengths of the spring like tabs will be at least 10% of the length of the shield and more preferably will be 50% of the length of the shield. 
     Referring particularly to FIG. 9, it will also be seen that there is a slot 106 at each end of the connector 102, which allows the tab 111 to pass through the connector to engage a recess 144 in the opposing card shield. Thus there is a completely metal to metal contact so that it is not necessary to engage the plastic in the connector 102. More particularly, if only two card shields 107 and 108 are engaged without using the connector 101 and 102 the resulting card case is rigid. 
     Referring to FIGS. 18-21, an embodiment is shown in which no I/O receptacle is employed. Otherwise this embodiment is generally the same as that described in FIGS. 9-17. That is, it has identical tabs 245 which engage identical recesses 254, and it also has a space 240 for an MTB connector (not shown). Referring particularly to FIGS. 20-21, it will be noted that the joining tabs and recesses of the rear are disposed to the side and there is centrally adjoining panels 241 and 242. Referring to FIGS. 22-24, another embodiment is shown which is similar to the foregoing embodiment except that it makes use of a single 15 position I/O connector 343. The tabs 309 and recesses 310 are the same as was described above. In this embodiment the connecting tabs and recesses 345 and 354 respectively are positioned outwardly adjacent the I/O connector on the front end of the card while tabs 311 and recess 344 cooperate with each other on the MTV connector side. 
     Referring to FIGS. 25-27, another embodiment is shown which makes use of two I/O connectors 446 and 447. Otherwise this embodiment is essentially the same as the ones described above. It will be noted that at the rear end of this card the tab and recess 448 are positioned between the I/O connectors and the rear side of the card. 
     Referring to FIGS. 28-29, it will be seen that the full metal corners of the embodiments described above are comprised of a folded metal wall shown generally at 549. Referring to FIGS. 30-31, it we be noted that this curved corner may be produced from a blank having a medial protrusion 450 and lateral protrusions 451 and 452 which may be folded upwardly and inwardly in segments to produce the desired rounded effect. Those skilled in the art will appreciate the advantages of the construction of this full metal corner in terms of EMI EST shielding or similar full metal shielding without use of plastic or open air. This feature is also aesthetically advantageous since it has no sharp edges. 
     Referring to FIG. 32a, an alternate preferred tab is shown in which a projection 550 extends from an arcuate member 552 which is thicker than the corresponding portion of the tab previously described. Referring to FIG. 32b, an alternate preferred embodiment of a recess is shown which was a projection 554. Opposed edges 556 and 558 extend outwardly respectively to points 560 and 562. 
     TEST 
     Torque, deflection and finger nail simulation tests were performed on the second embodiment of the card described above. Test protocols and results for such torque, deflection and finger nail simulation tests are shown on the following Tables I, II and III. 
     It will be appreciated that a card connector has been provided which allows for optimum shear strength and stiffness against bending and torsion. 
     While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims. 
     
                       TABLE I______________________________________1. Torque test  1/4 hard stainless steel, thickness 0.2 mm  Test conditions:  card kit consists of two shields plus two connectors, no PCB  applied torque is 1.236 [Nm]  torque is applied on the cards one time in each direction (instead of 5 times) torque has been applied on the cards for about 10 seconds (instead of 5 minutes) maximum torque is applied, even when maximum angle of 10° is exceeded test has been performed before bend test (according to PCMCIA spec.) and finger nail test  SAMPLE   TORQUE [nM]                 ROTATION ANGLE 17                              REMARKS______________________________________  1 1.236 11.3 clockwise  1 1.236 12.6 counter-clockwise  2 1.236 10.9 clockwise  2 1.236 11.7 counter-clockwise  average 1.236 11.63 no visibledamages at theoutside______________________________________ Conclusions: 1. maximum rotation angle occurs first 2. PCB or other elements inside the card can function as a spacer and wil increase the rigidity dramatically 
    
     
                       TABLE II______________________________________2. Bend test  1/4 hard stainless steel, thickness 0.2 mm  Test conditions:  card kit consists of two shields plus two connectors, no PCB  applied force is 19.6 [N]  test according to PCMCIA specification  clamping device is the gauge according to SK33279  cards are clamped quite firmly  test has been performed after torque test and before finger nail test  machine-settings:         y-axis: F = 500 N, rate 1:1, range 5 mV/cm (1 cm =   2.5 N)   x-axis: L = 5, rate 1:1, range 5 mV/cm (1 cm = 1 mm)SAMPLE  FORCE [N] DEFLECTION (mm)                           REMARKS______________________________________  1 20.7 3.6 I/O side clamped,up  1 20.2 3.3 I/O side clamped,down  1 20.2 2.3 68 pos sideclamped, up  1 20.5 4.0 68 pos sideclamped, down  2 20.2 3.4 I/O side clamped,up  2 20.1 3.4 I/O side clamped,down  2 20.6 3.1 68 pos sideclamped, up  2 20.4 2.9 68 pos sideclamped, down  average I/O 20.30 3.43  average 68 20.43 3.08  average all 20.36 3.25 no visible damagesat the outside______________________________________ Conclusions: 1. the version 2 card kit is very stiff in relation to competition and ou version 1 2. no difference in deflection between I/O side and 68 position side by optimized geometry and clamping more firmly 
    
     
                       TABLE III______________________________________3. Finger nail simulation tests  1/4 hard stainless steel, thickness 0.2 mm  The test kits have been approved by several people concerning the resistance against breaking open the kit by hand (including using your finger nails) Test conditions: card kit consists of two shields plus two connectors, no PCB card kit is clamped up to 14 mm from the sides test pin according to drawing SK35578 revision 1 grease is applied on the card kit and test pin to avoid stick-slip phenomenon test has been performed after respectively torque and bend test  machine-settings:         y-axis: F = 100N, rate 1:1, range 0.1 V/cm (1 cm =   50N)   x-axis: L = 50, rate 5:1, range 5 mV/cm (1 cm =   0.2 mm)           FORCE [N]                    DISPLACEMENT [mm]                                 REMARKS______________________________________SAMPLE 1  1 145 16 2.06 163  2 120 21 1.72 84  3 165 23 2.24 111  I/O 4 120 14 0.42 21  I/O 5 90 11 0.25 113  6 113 283  1.66 10  7 130 26 1.44 93  8 95 10 1.18 19  average 127.92  1.72  average I/O 105.00  0.34  SAMPLE 2  1 105 21 1.68 64  2 95 40 1.34 67  3 165 53 1.94 97  I/O 4 110 23 0.30 11  I/O 5 95 10 0.28 14  6 110 13 1.36 66  7 120 24 1.24 63  8 115 23 1.26 67  average 118.33  1.47  average I/O 102.50  0.29  long sides 123.13  1.59  average value  over two  samples  I/O side 103.75  0.31  average value  over two  samples  no visible  damages at the  outside______________________________________ Conclusions: 1. the forces to open the kit are quite high 2. the force at the I/O side is almost as high as at the long sides 3. the penetration depth at the I/O side is much lower than at the long sides 4. the force/displacement curves are capricious but reproducible 5. these results can be used in future as a reference