Abstract:
The invention relates to a plug comprising a plurality of contact elements located in a plug housing and strain relief elements ( 200, 200′ ) arranged on the housing ( 110, 310 ), wherein both contact elements and strain relief elements can be fixed to a printed circuit board ( 10 ) using SMT technology. The invention is characterized in that the strain relief elements ( 200, 200 ′) are sheet metal elements that can be fixed to parts of the plug housing and are bent essentially at a right angle on the side facing the printed circuit board ( 10 ), thereby forming a bearing surface ( 220, 220′ ) for SMT attach.

Description:
[0001]    The invention relates to a plug comprising a plurality of contact elements arranged in a plug housing and strain relief elements arranged on the housing, wherein both contact elements and strain relief elements can be fixed to a printed circuit board using SMT technology. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    Such plugs are marketed by the applicant under the product designation SMC plug connectors and are shown for example in the brochure D074497 February 2008 Edition 3 of the applicant, which can be downloaded from the applicant&#39;s website under http://ww.erni.com/db/pdf/smc/ERNI-SMC-Board-on-d.pdf. In these plug connectors, the strain relief elements are respectively fixed laterally transversely to the plug-in direction and substantially in extension of the fastening elements which are arranged on the longitudinal sides of the plug housing and are connected via plastic webs with the plug housing. The strain relief elements are punched sheet metal parts which are fixed to the fastening elements. The sheet metal elements comprise supporting surfaces for SMT fastening on the side facing the printed circuit board. These supporting surfaces respectively protrude laterally beyond the narrow sides of the housing. 
         [0003]    These plugs comprise male multipoint connectors and female multipoint connectors which respectively comprise such strain relief elements. In the mated state, the plug-in process will be substantially limited by the thickness of the laterally protruding plastic webs. Within the terms of a high level of mating reliability, i.e. within the terms of maximum mutual insertion, it is now desirable that the two plug connector parts (i.e. male multipoint connector and female multipoint connector) are inserted into each other as deeply as possible. For this reason the plastic web would have to be provided the thinnest possible configuration because the depth of mutual insertion of the two plug connector parts is limited by the thickness of the plastic web. However, this is not possible within the terms of optimal strain relief because the aforementioned strain relief elements are fixed to the fastening projections, which on their part are integrally formed on the web. A thin plastic web, however, does not have the desired stability. 
         [0004]    The invention is therefore based on the object of further developing such a plug in the respect that maximum mating reliability is ensured on the one hand (i.e. maximum mutual insertion of male multipoint connector and female multipoint connector) and optimal strain relief is ensured on the other hand. 
       ADVANTAGES OF THE INVENTION 
     Summary of the Invention 
       [0005]    This object is achieved by a plug of the kind described above in such a way that the strain relief elements are sheet metal elements that can be fixed to parts of the plug housing and are bent off substantially at a right angle on the side facing the printed circuit board, thereby forming a supporting surface for the SMT fastening. It is the fundamental idea of the invention to completely omit the laterally protruding plastic webs which are used for fastening the strain relief elements and to arrange the strain relief elements as sheet metal parts which can be fastened directly to a part of the plug housing and are bent off on the side facing the printed circuit board by forming a supporting surface. As a result, fastening devices which are integrally formed on the laterally protruding plastic webs can be omitted completely. It is rather the sheet metal elements themselves that form the strain relief, wherein the bent-off regions which form the supporting surface can be provided with a substantially thinner configuration as a result of the higher stability of sheet metal in comparison with plastic. As a result, maximum mating and therefore a very high level of mating reliability is enabled, i.e. maximum mutual insertion of the plug contact elements. 
         [0006]    Advantageous developments and improvements of the plug stated in the independent claim  1  are enabled by the measures stated in the dependent claims. 
         [0007]    An advantageous embodiment provides that the sheet metal elements can be fixed to webs which are simultaneously used for reverse polarity protection. These webs enable an especially stable fixing of the sheet metal elements to the plug housing which will also withstand high tensile forces. The webs are simultaneously used for reverse polarity protection. 
         [0008]    It is provided in an embodiment that the webs protrude beyond the plug housing both in the plug-in direction and also transversely to the plug-in direction and are therefore arranged in a substantially thicker and more massive configuration than the housing walls. This not only increases the stability of the fastening of the sheet metal elements, but also increases the sturdiness of the reverse polarity protection. 
         [0009]    It is provided in another embodiment that the webs protrude into the interior of the housing and are provided with a thicker and more massive configuration than the housing wall. This also leads to an increase in the stability of the fastening of the sheet metal elements. At the same time, the webs are used as sturdy reverse polarity protection. 
         [0010]    The sheet metal elements can principally be fixed to the webs in numerous ways. Adhesive connections, press connections or the like can principally be considered. 
         [0011]    An especially advantageous embodiment provides that the sheet metal elements can be fixed to the webs by latching connections. Such latching elements not only enable simple mounting but also simple production, e.g. by punching the sheet metal elements. 
         [0012]    An especially preferred embodiment provides that the sheet metal elements comprise four latching connections which are subdivided into two groups of two latching elements each, with the first group being arranged as close as possible to the printed circuit board and the second group as close as possible to the upper side of the plug. This also increases the stability of the plug fixed to a printed circuit board with respect to a torque exerted on the plug. The sturdiness of strain relief will also be increased substantially in this way. 
         [0013]    Preferably, the sheet metal elements that are bent off at a right angle form a rectangular supporting surface which extends perpendicularly to the plug-in direction and parallel to the printed circuit board by protruding beyond the sides of the housing. This configuration allows fixing the strain relief elements over a large area, with the supporting surface—other than in the state of the art—not being interrupted but arranged in a continuous way. 
         [0014]    The sheet metal elements are preferably punched parts which can be produced in a very rapid and precise way especially in mass production. Only bending processes are required after the punching process, i.e. the arrangement of the supporting surfaces arranged at a right angle and the arrangement of the latching elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Embodiments of the invention are shown in the drawings and are explained in closer detail in the description below, wherein the drawings show as follows: 
           [0016]      FIG. 1  shows an isometric view of a plug in accordance with the invention which is arranged on a printed circuit board and as a female multipoint connector; 
           [0017]      FIG. 2  shows the plug illustrated in  FIG. 1  prior to mounting the sheet metal elements used for strain relief; 
           [0018]      FIG. 3  shows an isometric view of a plug connector in accordance with the invention which is arranged as a male multipoint connector; 
           [0019]      FIG. 4  shows two plug connectors in accordance with the invention, a female multipoint connector and a male multipoint connector, prior to mating, and 
           [0020]      FIG. 5  shows a male multipoint connector and a female multipoint connector in accordance with the invention after mating. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Plugs will be explained below by reference to the drawings, which plugs can be arranged both as a female multipoint connector (cf.  FIG. 1  and  FIG. 2 ) and also as a male multipoint connector (cf.  FIG. 3 ). A female multipoint connector, which is designated in its entirety with reference numeral  100 , comprises a housing  110  in which spring contact elements (not shown) are arranged in the known manner. The housing  110  comprises openings  120  on its upper side  111  into which blade contacts can be inserted, which will be described below in closer detail. The spring contact elements comprise SMT solder pads  122  on their bottom side, which solder pads can protrude for example beyond the side areas  112  and are arranged on a printed circuit board  10 . Webs are arranged laterally on the housing  110 , which protrude beyond the housing both in the mating direction (designated with arrow R in  FIG. 1 ) and perpendicularly to the mating direction beyond the side surfaces  112  and  113  which delimit the housing. The webs  150  comprise projections  152  which are shaped in the manner of truncated pyramids and which are provided for insertion into recesses in a part of the housing ( FIG. 3 ) arranged as a male multipoint connector. The webs  150  are used on the one hand for reverse polarity protection and on the other hand strain relief elements  200  can be fixed to them which are arranged as sheet metal parts. The sheet metal parts have a substantially L-shaped contour, comprising a part  210  extending in the vertical direction and a sheet metal part  220  which is bent off therefrom at a right angle and extends parallel to the printed circuit board  10 . 
         [0022]    The sheet metal part  210  extending in the vertical direction comprises four latching elements  211 ,  212 , of which one group of two latching elements  211  is arranged as close as possible adjacent to the upper side  111  of the housing  110  of the plug connector  100  and a further pair of latching elements  212  is arranged as close as possible to the bent-off sheet metal part  220  and therefore the printed circuit board  10 . This arrangement of four latching elements in such a way that two respective pairs have the greatest possible distance from one another in the mating direction ensures secure fastening of the strain relief element  200  arranged as a sheet metal part and especially also sufficiently large sturdiness for example against breaking off of the plug  100  fixed to the printed circuit board by exerting a torque on said plug  100 . 
         [0023]    The bent-off part  220  of the strain relief element  200  is used as a supporting surface for SMT fastening to the printed circuit board. Said bent-off part  220  has a substantially rectangular shape, wherein it protrudes beyond the narrow side  113  transversely to the mating direction in order to provide the largest possible supporting surface. As a result, the solder pads  122  which are soldered onto the printed circuit board are effectively strain-relieved and therefore inadvertent interruption of the contacts of one or several of the solder pads  122  as a result of high tensile loading is prevented. 
         [0024]    As is shown in  FIG. 1 , the sheet metal element can be fixed to the web  150  in a recess  151  provided for this purpose. This is not mandatory however. Principally, the strain relief element  200  can also be fixed on the outside to the web, i.e. without recess. A recess  151  as shown in  FIG. 1  allows an especially compact configuration however. 
         [0025]      FIG. 2  shows the plug connector illustrated in  FIG. 1  shortly before the fixing of the strain relief elements  200 . The same elements are provided with the same reference numerals as in  FIG. 1 . The latching openings  153  can be recognized in the dismounted state, into which the latching elements  211 ,  212  of the strain relief element  200  will engage. The strain relief elements  200  are punched out of a sheet metal part, wherein the punching process merely needs to be followed by bending processes, i.e. the rectangular bending of the part  220  and the bending of the latching elements  211 ,  212 . The fixing of the strain relief elements  200  occurs by latching in the latching openings  153  in the webs  150 . 
         [0026]      FIG. 3  shows a plug connector  300  which is arranged as a male multipoint connector. Blade contacts  320  are arranged in the plug. Recesses  330  are respectively provided on either side of the blade contacts  320 , into which the aforementioned webs  150  can be inserted. For this purpose, the recesses  330  comprise inclined receiving openings  332  which are adjusted to the upper sides  152  of the webs, which sides are shaped in the manner of truncated pyramids. SMT pads  332  of the blade contacts  320  are provided which respectively face a printed circuit board (not shown). 
         [0027]    Strain relief elements  200 ′ are also provided in the plug shown in  FIG. 3 , which strain relief elements are arranged as sheet metal parts and comprise a part  210 ′, which extends substantially in the mating direction R and which can be fastened by latching elements  211 ′,  212 ′ to a web  350 , which, however, in contrast to the female multipoint connector protrudes into the interior of the plug housing, and a part  220 ′ which is bent off in a substantially rectangular way. A recess  351  is also provided in this case too, so that the strain relief element  200 ′ will not protrude laterally beyond the plug housing. The webs  350  are used for reverse polarity protection in this case too. They are used simultaneously for optimal fastening of the strain relief elements  200 ′ by means of the latching connections. The webs  350  enable a fixing by means of the latching elements  211 ′,  212 ′ which otherwise could protrude into the interior of the plug housing  310 . The bent-off part  220 ′ is herein bent off in such a way that it does not protrude laterally beyond the plug housing, but is directed inwardly facing the SMT pads  322  of the blade contacts  320 . This is not mandatory however. 
         [0028]    Rather, the bent-off part  220 ′ can also be bent off to the outside, as described above in conjunction with  FIG. 1  and  FIG. 2 . The solution shown in  FIG. 3  provides an especially compact configuration of the plug. The strain relief, which is formed by the rectangular area  220 ′ of the strain relief element  200 ′, protrudes slightly beyond the lateral boundary surfaces of the plug. 
         [0029]      FIG. 4  shows a female multipoint connector shown in  FIG. 1  and  FIG. 2  of a plug in accordance with the invention and a male multipoint connector situated above of a plug in accordance with the invention shortly before mating.  FIG. 4  also shows the centering pins  359  which engage into respectively arranged openings in the printed circuit board (not shown). These centering pins are also arranged in the respective manner in the female multipoint connector and are provided there with the reference numeral  159  (cf.  FIG. 2 ). 
         [0030]      FIG. 4  also shows in closer detail that the webs  150  protrude beyond the lateral boundary surfaces  112 ,  113  of the plug housing  110 . This is used for reverse polarity protection. Furthermore, this improves the stability of the plug, especially also the stability of the strain relief provided by the strain relief elements  200  arranged on the webs  150 . 
         [0031]      FIG. 5  finally shows the mated state of male multipoint connector and female multipoint connector. Maximum mating of male and female multipoint connector is enabled by the arrangement of the strain relief elements  200 ,  200 ′ in accordance with the invention. The male multipoint connector  300  can be inserted to such an extent into the female multipoint connector  100  that its upper side rests on the laterally protruding, bent-off part  220  of the strain relief elements  200 . Since this protruding part  220  consists of a bent-off sheet metal part which can be provided with a very thin configuration without consequently impairing stability, maximum mating of male and female multipoint connector is enabled and high mating reliability in combination with simultaneously optimal strain relief of both parts of the plug is consequently ensured, i.e. male multipoint connector and female multipoint connector, because the SMT area is large which is formed by the bent-off part  220 .