Abstract:
In a compact printed circuit board connector adapted to be mounted at a printed circuit board and intended to be soldered to the printed circuit board simultaneously with other electrical components in a heating oven by using a solder paste for soldering the components, a channel is provided which extends through the interior of the printed circuit board connector. The channel serves for circulating a flow of heated gas through the interior of the connector in order to quickly achieve the required soldering temperature at the soldering ends of the contact elements.

Description:
The invention relates to a printed circuit board connector. 
     BACKGROUND OF THE INVENTION 
     A typical printed circuit board connector comprises an isolating housing and contact elements which are arranged therein, are preferably formed angled and have a plug-in side, an intermediate portion and a connecting side with contact ends adapted to be mounted at a printed circuit board. 
     In order to provide a multiple pole plug-in connection, a complementary connector can be plugged into such a printed circuit board connector, the printed circuit board connector being either formed as male connector or female connector. The contact elements arranged in the isolating housing at the plug-in side in rows and columns have contacts which in case of a female connector are formed as spring contacts or in case of a male connector as contact blades and are provided for forming a contact with corresponding contact blades and contact springs, respectively, of the complementary connector. 
     At the other side of the housing, contact ends connected with the contact elements are provided, the contact ends being adapted to be connected with connecting portions of a printed circuit board. The contact ends are arranged at a right angle with respect to the plug-in direction of the connector. 
     Typically, the contact ends are soldered to the conductor tracks of the printed circuit board. A problem hereby is that all contact ends at the connecting side need to be heated as uniformly as possible in order to achieve a soldering point at each of the contact ends with an evenly high quality. 
     German Patent Publication 199 49 160 shows an electrical connector for connecting a conductor track on a printed circuit board, the connector having a housing with a front face and an opposite back face. In the housing are arranged contact chambers in rows and columns, in which angled electrical contacts for contacting a complementary connector accommodated. The contacts have an intermediate portion which is arranged at least partially outside of the housing, and further a solderable connecting portion for contacting and being soldered to a conductor track, the printed circuit board being contacted from two sides. 
     German Patent 195 17 977 shows an electronical component for being connected to a printed circuit board in a surface mounting technique, conducting elements made from an electrically conducting material being held in an isolating carrier material. The carrier element is provided with at least one window through which energy heating the contact portion can be radiated into the carrier element. 
     U.S. Pat. No. 5,115,964 shows a solder connection between a flexible circuit carrier and an electronical component. In order to allow to solder the soldering connections of the electronical component to the conductor tracks at the lower side of the circuit carrier, openings are provided in the dielectrical carrier layer of the circuit carrier whereby a heating gas used for soldering is able to heat the conductor tracks and to provide for an electrical connection with the soldering connections arranged below. 
     It is further known for printed circuit board connectors to have the contact elements completely embedded into an isolating housing with the exception of the protruding contact ends. This leads to high requirements with respect to the position accuracy of the connections to be placed, in particular with connectors which are positioned by means of handling robots on a printed circuit board. The high position accuracy is achieved by forming and mounting the housing of the connector in an exact manner and by using short protruding contact ends in order to prevent any bending of the contact ends. This means that the contact ends are embedded in the isolating housing to the highest possible extent. Accordingly, the contact ends of the contact elements which are for example bent by 90 degrees are mostly embedded in correspondingly shaped housing parts of an isolating housing. This can be achieved by contact elements which are inserted into segments or which are individually embedded and then combined in a carrier housing as a printed circuit board connector. 
     When components and connectors which are arranged at a printed circuit board are simultaneously soldered in a heating oven in which the energy means for heating a solder paste used as soldering means is a flow of heated air or gas, there is the risk that not all of the soldering ends of the contact elements reach the soldering temperature required for achieving an optimum soldering point simultaneously, that is at the same time with other components of the printed circuit board, this being due to the encapsulated and thereby thermally isolating construction of such printed circuit board connectors. In case of an excessive sejourn time in the heating oven, this can lead to an excessive temperature and to destruction of the electronical components, and an insufficient sejourn time can result in defective soldering points. 
     The invention is based on the object of improving a printed circuit board connector of the type initially mentioned so that all soldering ends of the contact elements are uniformly and without delay sufficiently exposed to a heating energy in order to allow for being soldered to a printed circuit board. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The invention provides a printed circuit board connector having an isolating housing, contact elements arranged in the housing, each the said contact elements comprising a plug-in side, an intermediate portion and a connecting side with contact ends adapted to be mounted at a printed circuit board, and having a plurality of channels which are in touch with the intermediate portions of the contact elements. The advantages provided by the invention particularly reside in the fact that the channel allows the heating gas to flow through the interior of the connector even when a large number of contact elements are arranged in rows in a staggered manner, the flow of heated gas allowing to quickly heat the internally arranged intermediate portions of the contact elements. Due to the good thermal conductivity of the contact elements made from metal, this allows to quickly heat the contact ends which leads to a uniform soldering. 
     The intermediate portions of the contact elements may project into the channel or be formed adjacent thereto. In any case, it is important to achieve a good heat transfer from the medium flowing through the channel to the intermediate portions. 
     According to a preferred embodiment of the invention, the channel is formed from a first partial channel extending approximately perpendicularly with respect to the printed circuit board, and a second partial channel extending approximately parallel to the printed circuit board. The first partial channel can be formed by a recess extending approximately perpendicularly with respect to the printed circuit board, the recess being formed in segments which accommodate the contact elements. The second partial channel can be formed by a distance between the surface of the printed circuit board and intermediate walls of a segment holder which holds the segments accommodating the contact elements. The distance between the intermediate walls of the segment holder and the surface of the printed circuit board may change over the intermediate wall. Using two partial channels which are perpendicularly with respect to each other allows to use a printed circuit board without an opening which is aligned with the channel extending perpendicularly with respect to the printed circuit board. Accordingly, the printed circuit board need not be adapted to the connector, which is an advantage. The partial channel extending perpendicularly with respect to the printed circuit board assists in the circulation of the hot gases through the channel by acting in the manner of a chimney. 
     According to the preferred embodiment, a second channel extending approximately perpendicularly with respect to the printed circuit board is provided at the plug-in portion of the contact elements in the isolating housing. This allows to heat the contact elements arranged in the inner centre. 
     An additional advantage results from suitably formed contact ends of the contact elements which allows to use contact elements with press-in contact ends in an otherwise unchanged housing. This is advantageous since the angled printed circuit board connector intended for being soldered in surface mounting technique can be pressed into bores in a printed circuit board with a simple, flat tool. 
     Advantageous details of the invention are specified in the subclaims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings show an embodiment of the invention which is explained in detail below. In the drawings, 
     FIG. 1 shows a sectional view of a printed circuit board connector with two channels, 
     FIG. 2 shows an isometric view of a completely mounted printed circuit board connector, 
     FIG. 3 a  shows an isometric view of a carrier body with a plug-in pattern of the printed circuit board connector, 
     FIG. 3 b  shows an isometric view of the carrier body rotated by 180 degrees, 
     FIG. 4 a  shows an isometric view of a segment, 
     FIG. 4 b  shows an isometric view of a segment with a recess for forming a channel, 
     FIG. 5 a  shows an isometric view of a segment holder, and 
     FIG. 5 b  shows a lateral view of an intermediate wall of the segment holder. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a printed circuit board connector in a cross section, the printed circuit board connector being placed on a printed circuit board  9  and having contact elements  40 . Each contact element consists of a contact spring  41 , a contact end  43  which is formed as soldering end and engages into bores in the printed circuit board  9 , and an intermediate portion  44  connecting the contact spring to the contact end. 
     The forward portion of the printed circuit board connector  1  which is here formed angled is arranged with his plug-in face  11  in front of the printed circuit board, at least the lowest contact element  45  with its spring contact  41  formed as female contact being arranged below the printed circuit board  9 . In this embodiment of the printed circuit board connector, two channels are provided which are independent from each other, namely a first channel  6  and a second channel  5 , which are here symbolised by arrows. These arrows indicate the heated air circulating through the channels, which can directly pass over the exposed intermediate portions  44  of the contact elements  40 . 
     The second channel  5  is provided in the forward plug-in portion of the printed circuit board connector perpendicularly to the plug-in direction and perpendicularly to the printed circuit board  9 . It is formed as rectangular cavity and is accessible by respective openings  13 ,  16  in the outer wall above and below the carrier body  10 . 
     The channel  5  is situated such that the root  42  of the contact spring  41  is lying in the flow of the hot gas which results in particularly heating the lowest contact element  45  in addition to the other contact elements. 
     The first channel  6  is formed by a first partial channel  7 , which extends perpendicularly with respect to the printed circuit board  9 , and a second partial channel  8 , which extends parallel to the printed circuit board. Here again, the two partial channels are symbolised by arrows which indicate the flow of gas through the channels. 
     Partial channel  8  is limited on the one hand by the printed circuit board and on the other hand by an outer wall  23  of intermediate walls  21  of a segment holder  20  (please refer to FIG. 5 b ), the intermediate walls  21  being formed in a comb-like manner and the outer wall  23  being formed spaced from the printed circuit board  9  and inclined thereto. Partial channel  7  which adjoins perpendicularly to partial channel  8  is formed by a recess  31  in a segment  30  and by the intermediate wall  21  of segment holder  20  adjacent to the segment. The segment accommodates a contact element. 
     FIG. 2 shows an isometric view of a completed printed circuit board connector with the second channel  5  and the first channel  6  formed from a combination of partial channels  7 ,  8 . 
     The printed circuit board connector is formed from the following components: carrier body  10 , segment holder  20  and segments  30  inserted into the carrier body, mounting of the printed circuit board connector beginning with insertion of the contact elements  40  into accommodations  32  in the segments  30 . Thereafter, the segments  30  are inserted between guiding webs  17  within an accommodation opening in the carrier body  10 , and finally the segment holder  20  is inserted into the open intermediate spaces between the segments  30 . 
     FIG. 3 a  shows the carrier body  10  of the printed circuit board connector with the plug-in face  11  and the symmetrical arrangement of the insertion funnels for the blade contacts of a complementary connector, which are arranged in columns and rows. 
     Further, openings  13 ,  14  serving as exit for channels  5 ,  6  can be seen in cover  12 , and latching openings  15  into which latches  24  of the segment holder  20  engage when the segment holder  20  is positively engaged on the carrier body  10 . 
     FIG. 3 b  shows the interior of the carrier body which allows to see the guide webs  17  mentioned with respect to FIG.  2  and forming a separating guide between which the individual segments are inserted. In addition, openings  16  of channels  5  can be seen at the bottom side in the forward plug-in portion. 
     In FIG. 4 a  is shown in an isometric view a segment  30  of the printed circuit board connector with the accommodations  32  which are formed differently depending from the dimensions of the contact elements  40  to be accommodated. Upon mounting of the printed circuit board connector, a latch  22  of segment holder  20  engages into a groove  33  whereby the segments  30  are held in the carrier body  10 . 
     In FIG. 4 b , the backward side of the segment  30  shown in FIG. 4 a  is depicted also in an isometric view. Clearly visible is recess  31  which together with adjacent intermediate wall  21  of segment holder  20  forms a partial channel  7  upon completion of the connector. 
     When the printed circuit board connector is mounted, first the individual segments  30  with contact elements  40  accommodated therein are inserted between the guide webs  17  at the inner side of cover  12  of carrier body  10  which provides hold for the segments  30  at one side. The final hold of the segments in the connector is achieved by means of latches  22  at the rear wall of segment holder  20 , which engage in the two grooves  33  of the segments  30 . 
     FIG. 5 a  shows segment holder  20  for the individual segments  30  in an isometric view. Segment holder  20  is formed comb-like with a plurality of intermediate walls  21  protruding from a rear wall. Upon completion of the connector, the segments  30  are positively fixed between the intermediate walls  21  which are formed even at both sides. 
     Elastical latching tongues  24  which are provided at some of the intermediate walls, latch into latching openings  15  in the cover  12  of the carrier body  10  upon mounting and together with the latches  22  of the segment holder, which engage into the grooves  33  of the segments, prevent the connector from disassembling. 
     FIG. 5 b  shows an intermediate wall  21  of segment holder  20  in a lateral view. Here, the obliquely extending outer wall  23  is visible. The outer wall  23  together with the printed circuit board  9  forms the horizontally extending partial channel  8  after mounting the connector at the printed circuit board. 
     In an alternative embodiment, channels for the hot gas can also be provided in a connector of this type having straight contact elements.