The invention relates to a plug connector, especially for SMD (xe2x80x9csurface-mounted devicexe2x80x9d) plugs, for connection of electronic devices.
Plug connectors are known and commonly used in diverse configurations. They have two plug-connector elements, which can be mutually engaged, and they are provided with a plurality of electrically conductive contacts that establish electrically conductive connections. The SMD plug connectors are plugged onto a printed-circuit board and detachably fixed by a snap fastening. Snap-in projections in the form of barbs engage in corresponding snap-in recesses. The plug-connector element disposed on the printed-circuit board can be detachably connected with another plug-connector element of complementary geometry. This permits the printed-circuit board to couple to a multi-conductor cable that has the other plug-connector element at its end.
It is known that the influence of external electromagnetic fields on a plug connector can be reduced by providing a shield plate of electrically conductive material on both plug-connector elements. This configuration also prevents electrical crosstalk in a plug connector. The shield plate surrounds their electrical contacts. These shield plates additionally function automatically as bonding conductors for grounding the plug connector or the printed-circuit board.
Under these conditions the problem of permanent electrical contact of the shield plates arises. This is especially true for plug-connector elements mounted permanently on the printed-circuit boards. In addition, the assembly process is considerably complex when a plug connector is to be equipped with a shield plate. Furthermore, a satisfactory solution has not yet been achieved for the electrical contact of these shield plates with one another.
A person skilled in the art is faced with the object of designing a plug connector with shield plates in such a way that electrically conductive contact of the two shield plates with one another is permanently assured and that the shield plates can be contacted reliably with the associated printed-circuit board.
The central idea of the present invention is that, during assembly of a plug-connector element, the shield plates are automatically fixed via snap fastenings, so that displacement of the shield plate relative to the plug-connector element is prevented. It is ensured that, when the two plug-connector elements are coupled with one another, the respective shield plates bear directly against one another over substantially their entire surface. In other words, the shield plates are predominantly flush with their body areas facing one another, and do not slip. For this purpose the shield plates are constructed in the form of substantially flat metal components. Furthermore, soldering tags are formed on the shield plates, and project out of or extend beyond the connector-element body, which is usually a plastic injection-molded part. These soldering tags allow the plug-connector element with the shield plate to be permanently contacted with a printed-circuit board using a dip-soldering technique. The soldering tags are additionally used to position and align the shield plates during assembly of the plug-connector element and during plugging of the plug-connector element onto a wiring board. In the process the soldering tags extending beyond the plug-connector element are introduced into corresponding recesses of a wiring board or similar component, whereupon the element is automatically aligned in correct position. In addition, an appropriate retaining force for fastening the element is applied with a subsequently made soldered connection.
The shield plate and the soldering tags of the corresponding plug-connector element are connected in the same way to the bonding conductor of the multi-conductor electrical connecting cable.
Preferably the plug-connector elements are constructed in the form of male and female multipoint connectors in each of which a plurality of electrical contact blades and sockets are disposed. Multipoint connectors generally have a rectangular body. These multipoint connectors are provided with snap-in projections or recesses, into which corresponding snap-in projections or recesses of the correspondingly shaped shield plate can be inserted to form a snap fastening. For this purpose the shield plate is preferably designed so that it comprises a continuous enclosure around the electrical contacts shielding the connection completely. The shield plate is at least along one of the side walls, preferably a long side of the plug-connector element. It can also have multi-piece construction.
To couple the male multipoint connector with the female multipoint connector, the male multipoint connector is provided with a receiving cavity into which the female multipoint connector can be introduced. For this purpose the blades of the male multipoint connector project from the base of the receiving cavity into the receiving cavity, and are contacted by the sockets arrayed in the female multipoint connector. The shield plates on the multipoint connectors are arranged so that the shield plate of the male multipoint connector is directly disposed on the inside of the receiving cavity and bears substantially against the body of the male multipoint connector, or the wall of the injection-molded part surrounding the receiving cavity. Correspondingly, the shield plate of the female multipoint connector is disposed on its exterior peripheral face. In the coupled condition of the two multipoint connectors, the flat and plane regions of the plates, facing one another, bear substantially completely and directly against one another.
To ensure that the two multipoint connectors are correctly positioned when plugged one into the other, guide elements are formed on the multipoint connectors. The guide elements have the form of projections, which extend outward beyond the body of the multipoint connector in plug-in direction and can be inserted into corresponding recesses on the other multipoint connector. This prevents the risk of skewed plugging of the two multipoint connectors and of bending of the blades or sockets.
It is also proposed that corresponding projections for guiding and aligning the multipoint connectors be provided on the shield plates, so that they also have one-piece construction.
To simplify plugging the two multipoint connectors one into the other, the edges or end regions of the shield plates pointing in the plug-in direction, are chamfered or are inclined relative to the body of the shield plate. The edges of the male multipoint connector are directed outward relative to the body and those of the female multipoint connector are directed inward relative to the body. Viewed in cross section, the portions each have symmetrical structure that either flares in the manner of a funnel or tapers in the manner of a pyramid. This facilitates the introduction of the one multipoint connector into the other even if the alignment is not exact.
SMD plug-connector elements or leads are formed on the shield plates. This ensures that the shield plates are contacted and the electrical connections are shielded in the coupled condition. During assembly, therefore, the SMD lead of a shield plate of a plug-connector element is electrically contacted with, the printed-circuit board or wiring board onto which the plug-connector element is plugged.