IC Card Connector Shield Grounding

IC cards, which are of about the same width and length as a typical credit card, have dimensions defined by PCMCIA (Personal Computer Memory Card International Association). Such cards have a width and length of 54 mm and 85.6 mm, respectively, with three different types having thicknesses of 3.3 mm, 5 mm, and 10.6 mm. Recent cards allow connection of the card to a local area network (LAN) by providing a receptacle connector at the rear of the IC card. An adapter cable assembly has a plug connector at its front end that plugs into the receptacle connector at the rear of the card. U.S. Pat. Nos. 5,387,110 and 5,411,402 describe plug connectors of this type, which have latches at their middles.

Newer IC cards require greater numbers of contacts. A latching mechanism for retaining a plug connector to the rear of the card, may occupy space that otherwise could hold several contacts, which makes even less space available. When the plug and receptacle contacts mate, electrical ground planes or grounds of the plug and receptacle connectors and/or their corresponding circuit boards must be connected. If grounding is to occur through regular pin and socket contacts, then such grounding contacts may not have sufficient current-carrying capacity, and they waste space that could otherwise be occupied by signal contacts. Also, there may be a substantial buildup of static electricity in the plug or receptacle, and a spark created as contacts closely approach each other, could damage adjacent contacts, especially in the case of pin contacts wherein there is no insulation between the free ends of adjacent pins. Plug and receptacle connectors which facilitated grounding to each other while minimizing the amount of space required for the grounding connections and while isolating any sparks created during mating from signal-carrying contacts, would be of value.

In accordance with one embodiment of the present invention, plug and receptacle connectors and their combination are provided with means for connecting together the grounds of the connectors and/or corresponding circuit boards in a manner that minimizes space required for mating grounding terminals while protecting signal contacts from sparks. The receptacle connector includes a grounded sheet metal shield surrounding the dielectric receptacle housing, while the plug connector has a grounded member that engages the receptacle shield during mating. The receptacle shield has a tab that is joined, as by soldering, to a grounded trace on its corresponding circuit board, while the plug grounded member has a tab that is joined to a grounded trace on its corresponding circuit board. The plug grounded member has a terminal portion that lies in a groove at a side of the plug dielectric housing, with the plug terminal portion having a part that projects slightly from the groove to engage the shield. The shield includes an elongated strip that is bent about 180.degree. and which engages the projecting part on the plug ground member.

The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.

FIG. 1 is an exploded isometric view of a portion of a connector system which includes a plug connector that is mateable with a receptacle connector that lies at the rear of an IC card.

FIG. 2 is an exploded sectional top view of a portion of the system of FIG. 1.

FIG. 3 is an exploded isometric view of a portion of the connector system of FIG. 1, showing portions of the dielectric housings and circuit boards of the connectors.

FIG. 4 is an enlarged plan view of a portion of the plug connector of FIG. 2.

FIG. 5 is a side elevation view of an upper shield member of the receptacle shield of FIG. 3.

FIG. 6 is a sectional side view of the lower shield member of the receptacle shield of FIG. 3.

FIG. 7 is a partial plan view of the lower shield member of FIG. 6.

FIG. 8 is a partial isometric view of the dielectric receptacle housing of the receptacle of FIG. 3.

FIG. 9 is a view of a portion of the lower shield member of FIG. 6, and showing a portion of the plug ground member of the plug connector of FIG. 4, in the course of connector mating.

FIG. 1 illustrates a connector system 10 that includes a plug connector 12 lying at the front of a cable 14, and a receptacle connector 16 lying at the rear of an IC card 18 of the PCMCIA type. Such IC cards generally have a width of 54 mm and length of 85.6 mm, and a thickness that may range between 3.3 mm and 10.5 mm, with the particular card illustrated being a type II card which has a thickness of 5 mm. The plug connector has laterally opposite sides 24, 26 front and rear ends 30, 32 and a top and bottom 20, 22, and is mated to the receptacle connector by moving the plug connector forwardly in the direction F along a plug connector axis 34. The connectors are symmetrical about a vertical plane extending through the axis 34. During mating, socket contacts 36 of the plug connector mate with pin contacts 38 of the receptacle connector. Forward and rearward directions are indicated by arrows F, R, up and down directions are indicated by arrows U, D, and lateral directions are indicated by arrow L.

As shown in FIG. 2, each connector has a latch region 50, 52, which is designed to contain a latch mechanism. A variety of latch mechanisms are available, such as those shown in U.S. Pat. Nos. 5,387,110 and 5,411,402. FIG. 2 indicates a latch mechanism in phantom lines, by a latch 40 on the plug connector and a latch-receiving recess 42 on the receptacle connector.

The plug connector 12 has a dielectric plug housing 54 with front and rear portions 56, 58 and laterally opposite side walls 57, 59. The rear portion 58 is connected to a plug circuit board 60. The plug connector has two laterally-extending rows of socket-type plug contacts 36. The circuit board has a front portion 64 that holds a laterally (in direction L) extending row of conductive traces 66 on both its upper and lower faces, with the socket contacts having tails 70 that are joined to the traces as by soldering.

The receptacle connector 16 has a dielectric receptacle housing 80, and the card 18 which includes a receptacle circuit board 82. The receptacle connector has a row of receptacle contacts 38 with pin-type rear ends 86. Each receptacle contact has a middle 90 anchored in the receptacle housing 80 as by being molded in place, and has a tail 92 at its front end. The circuit board 82 has a row of electrically conductive traces 94 to which the contact tails are joined, as by soldering. The circuit board is shown having two rows of traces 94, 96, one for contacts of the upper row and one for contacts of the lower row.

As shown in FIG. 3, the receptacle connector 16 includes a sheet metal shield 100 that lies immediately above, below, and on laterally opposite sides of the receptacle housing 80. As also shown in FIG. 8, the receptacle housing 80 has a top and bottom 102, 104 and opposite sides 106. Referring to FIG. 3, it can be seen that the receptacle housing forms a hollow region or hollow 110 at its rear end, and the pin-type free ends 86 of the receptacle contacts lie within the hollow. The presence of the shield is especially important where high frequency signals are carried.

Applicant forms the shield with a ground receptacle terminal or terminal portion 120 in the form of a bent elongated strip of the sheet metal of which the shield is formed. As shown in FIGS. 6 and 7, the strip extends from a rear edge 122 of the shield and has a substantially 180.degree. bend 124 near where it emerges from the end, with the rest of the strip extending substantially forwardly and lying within the rest of the shield. As indicated in FIG. 8, the dielectric receptacle housing 80 has a slot or groove 130 that receives the bent elongated strip shown in FIG. 7 at 120. The bent strip or receptacle ground terminal provides a smooth surface and also adds resilience to aid in contacting a grounded terminal portion of the plug connector.

As shown in FIG. 3, the plug connector housing 54 has a top and bottom and opposite sides, and has a recess or groove 140 in each of its sides. A plug ground member 142 has a forward terminal portion 144 lying in the groove, with a bent contact part 146 thereof projecting sidewardly out of the groove. The sheet metal of the forward terminal portion 144 lies in substantially vertical planes, and has a greater vertical height than its thickness. When the connectors mate, the plug housing 54 fits within the hollow 110 at the rear of the receptacle connector housing. During such mating, the projecting part 146 of the plug ground member engages the bent strip 120 formed on the shield of the receptacle connector. Such engagement occupies very little of the lateral width of the connector, which is usually less than the space that would be occupied by a pin-type terminal 84 (plus the space required around it). Also, any sparks created during mating of the projection 146 with the bent strip 120 is largely shielded from the signal-carrying contacts by the dielectric plug housing 54. The grounded terminal portions 144, 120 have a large cross-section which is usually greater than that of the pin free ends 86 to carry large grounding currents. Furthermore, the grounding of the receptacle occurs at the strip 120 which is part of the rest of the sheet metal shield 100, so that it is not necessary to provide a connection between a pin type contact and the shield or to make any solder or weld joints therealong.

The receptacle circuit board has an electrically grounded receptacle trace 160. The sheet metal shield 100 is provided with a tab 162 which is bent and which has a ground terminal portion 164 which is joined to the grounded trace 160 as by soldering thereto. As can be seen in FIG. 2, the grounded trace 160 lies immediately forward of the latch region 52 that would be occupied by a cavity 42 to which a latch on the plug connector would latch. Accordingly, the space at the trace 160 could not otherwise be occupied by contact pads so long as a latch-receiving cavity lies at the middle of the connectors. By applicant providing the grounded trace 160 on this location, the grounded trace 160 does not occupy space that otherwise would be used, and a wide large current-carrying capacity tab can connect to the grounded trace.

As shown in FIG. 3, the plug ground member 142 has a rear portion 170 that forms a tab 172 which is joined to an electrical ground plug trace 174 on the plug circuit board 60. The tab can lie at 172A to connect to the bottom face of a higher circuit board.

It can be seen from FIG. 3, that the shield 100 has upper and lower shield members 170, 172. The upper shield member is provided with a pair of locking ears 175 that project into locking slots formed in the lower member. As a result, the shield can be readily placed around the receptacle connector housing 80 by moving the lower shield up and the upper shield down, until the ears 175 snap into the slots 176, at which time the tab ground portion 164 will lie against the circuit board ground trace 160.

Both the plug housing 54 and receptacle housing 80 are of largely parallelepiped shape, with largely parallel top and bottom surfaces and largely parallel laterally-spaced opposite sides. The hollow 110 is preferably formed so that it has a narrow upper end 180 and a slightly wider lower end 182, to form a polarizing keyway that receives a correspondingly polarized plug connector housing 54. Applicant prefers to make the grounding connection at the opposite ends of the wider lower housing ends, where the grounding contacts are spaced slightly more from the signal-carrying contacts.

In a system that applicant has designed, the shield 100 had a lateral width of 1.14 inch, a height of 0.17 inch, and a front-to-rear length (not including tab 162) of 0.314 inch. The upper and lower interrupted rows of contacts each included eighteen contacts spaced at a 0.050 inch pitch.

Although terms such as "upper", "lower", etc. are used to aid in the description of the parts as illustrated, the connectors and other parts can be used in any orientation with respect to Earth's gravity.

Thus, the invention provides plug and receptacle connectors and the combination of the connectors and circuit boards of a plug and an electronic device such as an IC card, with an enhanced electrical grounding arrangement. The receptacle connector is provided with an electrically grounded sheet metal shield, while the plug connector is provided with a plug grounding member for engaging the shield. The engaging portions preferably lie at opposite sides of the respective housings, and preferably within the wider keyways or keys thereof. The shield has a tab that is joined to a grounded conductive trace on a circuit board associated with the receptacle connector. The plug grounding member has a rear portion forming a tab that is joined to a grounded trace on the plug circuit board. The plug grounding member preferably has a forward terminal portion lying in a groove at the side of the dielectric plug housing, and has a bent laterally projecting portion. The shield of the receptacle connector preferably has an elongated strip that is bent about 180.degree. to form a terminal for engaging the corresponding terminal formed by the plug grounding member.

Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.