Abstract:
A connector includes a first connector member configured to arrange a plurality of plane first boards with gaps in a thickness direction of the first boards, the first board including a conductive layer and an insulation layer, the insulation layer having a surface where a first signal pattern is formed; and a second connector member configured to arrange a plurality of plane second boards with gaps in a thickness direction of the second boards, the second board including a conductive layer and an insulation layer, the insulation layer having a surface where a second signal pattern is formed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based upon and claims the benefit of priority of Japanese Patent Application No. 2010-124144 filed on May 31, 2010, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to connectors configured to transfer a high frequency signal. More specifically, the present invention relates to a connector configured to reduce insertion loss at a high frequency band. 
     2. Description of the Related Art 
     A connector including a wiring board having a three layer structure where an insulation layer is formed on a metal plate and a wiring pattern is formed on the insulation layer has been suggested by inventors of the present invention. See, for example, Japanese Laid-Open Patent Application Publication No. 2008-209305. 
       FIG. 1  is a perspective view showing a structure of a related art wiring board  50  having a three layer structure, the wiring board  50  being included in the above-mentioned connector. The wiring board  50  has a three layer structure formed of a metal plate  51  made of phosphor bronze or the like, an insulation layer  52  made of polyimide or the like, and a wiring pattern  53  made of Cu, Al, or the like. A contact  54 , including ground contacts  54 G ( 54 G 1  through  54 G 4 ) and signal contacts  54 S, extends from an edge part of these three layers. 
     The contact  54  has a main body similar to that of the wiring board  50 , which has a three layer structure formed of the metal plate  51 , the insulation layer  52 , and the wiring pattern  53 . The ground contact  54 G 1  which is one of the ground contacts  54 G includes a ground wiring pattern  53 G 1 . The ground wiring pattern  53 G 1  is connected to the metal plate  51  via a piercing hole  55 G 1 . A pair of signal contacts  54 S 1  and  54 S 2  among the signal contacts  54 S include signal wiring patterns  53 S 1  and  53 S 2  extending toward an edge part in a Z 2  direction on the wiring board  50 . The other ground contacts  54 G 2  through  54 G 4  and other signal contacts  54 S 3  through  54 S 8  have substantially the same structures. 
     In addition, the ground contacts  54 G are provided so as to sandwich pairs of the signal contacts  54 S in a Z 1 -Z 2  direction. For example, a pair of signal contacts  54 S 1  and  54 S 2  is provided between the ground contact  54 G 1  and the ground contact  54 G 2 . In the wiring board  50 , the wiring pattern  53  of each of the contacts  54  is made to elastically come in contact with a wiring pattern of a corresponding wiring body (not illustrated in  FIG. 1 ) provided separately, where the wiring patterns are electrically connected to each other. 
     SUMMARY OF THE INVENTION 
     Accordingly, embodiments of the present invention may provide a novel and useful connector solving one or more of the problems discussed above. 
     More specifically, the embodiments of the present invention may provide a connector configured to reduce insertion loss in a case where a wiring board having a three layer structure is connected to another wiring board. 
     Another aspect of the embodiments of the present invention may be to provide a connector, including:
         a first connector member configured to arrange a plurality of plane first boards with gaps in a thickness direction of the first boards, the first board including a conductive layer and an insulation layer, the insulation layer having a surface where a first signal pattern is formed; and   a second connector member configured to arrange a plurality of plane second boards with gaps in a thickness direction of the second boards, the second board including a conductive layer and an insulation layer, the insulation layer having a surface where a second signal pattern is formed;   wherein the first board of the first connector member, by connecting the first connector member and the second connector member to each other, makes the first signal pattern provided on a surface of a contact extending from an edge at a side facing the second connector member toward the second connector member come in contact with the second signal pattern provided on a surface of one of the plural second boards of the second connector member, and makes the conductive layer provided at a head end of the contact come in contact with the conductive layer of another one of the plural second boards.       

     Another aspect of the embodiments of the present invention may be to provide a connector, including:
         a first connector member having a plane first board, the first board including a conductive layer and an insulation layer, the insulation layer having a surface where a first signal pattern is formed; and   a second connector member having a plane second board and a conductive board, the second board including a conductive layer and an insulation layer, the insulation layer having a surface where a second signal pattern is formed;   wherein the first board of the first connector member, by connecting the first connector member and the second connector member to each other, makes the first signal pattern provided on a surface of a contact extending from an edge at a side facing the second connector member toward the second connector member come in contact with the second signal pattern provided on a surface of the second board of the second connector member, and makes the conductive layer provided at a head end of the contact come in contact with the conductive board of the second connector member.       

     According to the embodiment of the present invention, it is possible to provide a connector configured to reduce insertion loss in a case where a wiring board having a three layer structure is connected to another wiring board. 
     Additional objects and advantages of the embodiments are set forth in part in the description which follows, and in part will become obvious from the description, or may be learned by practice of the invention. The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a structure of a related art wiring board having a three layer structure; 
         FIG. 2  is an exploded perspective view of a connector of an embodiment of the present invention; 
         FIG. 3  is a perspective view showing a jack connector slice; 
         FIG. 4  is a perspective view showing a plug connector slice; 
         FIG. 5  is a perspective view showing a piece of blade included in the plug connector slice; 
         FIG. 6  is an assembly perspective view of a connector of the embodiment of the present invention; 
         FIG. 7  is a perspective view showing a connector slice; 
         FIG. 8  is an expanded perspective view of a rectangular shaped area R 1  indicated by a dotted line in  FIG. 3 ; 
         FIG. 9  is a reverse view of the jack connector slice in  FIG. 8 ; 
         FIG. 10  is an expanded perspective view of a rectangular shaped area R 2  indicated by a dotted line in  FIG. 5 ; 
         FIG. 11  is an expanded perspective view of a rectangular shaped area R 3  indicated by a dotted line in  FIG. 7 ; 
         FIG. 12  is a view showing a connecting relationship between conductive patterns of the jack connector slice and conductive patterns of the plug connector slice; 
         FIG. 13  is a view of combinations of  FIG. 11  seen in various directions; and 
         FIG. 14  is a view showing a relationship between a contact configuration of the connector and transition of insertion loss relative to a signal frequency. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description is given below, with reference to the  FIG. 2  through  FIG. 14  of embodiments of the present invention. 
       FIG. 2  is an exploded perspective view of a connector  100  of an embodiment of the present invention. The connector  100  is, for example, a differential transmission type high speed transmission connector. The connector  100  includes a backplane board side jack connector  10  and a system board side plug connector  20 . 
       FIG. 3  is a perspective view showing a jack connector slice  10 SL which corresponds to a slash line part of the backplane board side jack connector  10  shown in  FIG. 2 . Similarly,  FIG. 4  is a perspective view showing a plug connector slice  20 SL which corresponds to a slash line part of the system board side plug connector  20  shown in  FIG. 2 .  FIG. 5  is a perspective view showing a piece of blade  20 B included in the plug connector slice  20 SL. 
     As shown in  FIG. 2 , the backplane board side jack connector  10  has a structure where plural (eight in this embodiment) jack connector slices  10 SL are arranged in a Z 1 -Z 2  direction. Each of the jack connector slices  10 SL may be formed as a module structure which can be exchanged and which has the same function. As shown in  FIG. 3 , the backplane board side jack connector  10  is connected to a backplane board (not illustrated in  FIG. 3 ) via a lead part  18  of each of the jack connector slices  10 SL by using solder or a conductive adhesive. 
     In addition, as shown in  FIG. 2 , the system board side plug connector  20  has a structure where plural (eight in this embodiment) plug connector slices  20 SL (see  FIG. 4 ) are arranged in a Z 1 -Z 2  direction. The plug connector slices  20 SL may be formed as module structures which can be exchanged and which have the same function. As shown in  FIG. 4 , the system board side plug connector  20 , as well as the backplane board side jack connector  10 , is connected to a system board (not illustrated in  FIG. 4 ) via a lead part  28  connected to blades  20 B of each of the plug connector slices  20 SL by using solder or a conductive adhesive. 
       FIG. 6  is an assembly perspective view of the connector  100  of the embodiment of the present invention.  FIG. 6  shows a state where the system board side plug connector  20  is inserted in the backplane board side jack connector  10 .  FIG. 7  is a perspective view showing a connector slice  100 SL which corresponds to a slash line part of the connector  100  shown in  FIG. 6 . The connector slice  100 SL is formed by combining the jack connector slice  10 SL and the plug connector slice  20 SL. 
       FIG. 8  is an expanded perspective view of a rectangular shaped area R 1  indicated by a dotted line in  FIG. 3 , where a direction of the rectangular shaped area R 1  is changed.  FIG. 9  is a reverse view of the jack connector slice in  FIG. 8 .  FIG. 10  is an expanded perspective view of a rectangular shaped area R 2  indicated by a dotted line in  FIG. 5 , where a direction of the rectangular shaped area R 2  is changed. 
       FIG. 11  is an expanded perspective view of a rectangular shaped area R 3  indicated by a dotted line in  FIG. 7 , where a direction of the rectangular shaped area R 3  is changed.  FIG. 11  shows the following state. That is, neighboring two jack connector slices  10 SL 1  and  10 SL 2  are arranged with a gap in a Z 1 -Z 2  direction. A single plug connector slice  20 SL is inserted between the neighboring two jack connector slices  10 SL 1  and  10 SL 2 . 
     As shown in  FIG. 8  and  FIG. 9 , the jack connector slice  10 SL includes a conductive board  11 , an insulation layer  12 , and a conductive pattern  13 . The conductive board  11  has a planar-plate shaped configuration and extends in X and Y directions. A pattern of the conductive layer  12  is formed at a Z 1  side of the conductive board  11 . A conductive pattern  13  is formed at a Z 1  side of the insulation layer  12 . 
     The conductive board  11  is formed by, for example, stamping a plate. The insulation layer  12  is formed by, for example, impregnating the conductive board  11  with insulation resin or adhering the insulation resin by insert molding. 
     The conductive pattern  13  includes plural ground patterns  13 G ( 13 G 1  through  13 G 3 ) and signal patterns  13 S ( 1381  through  13 S 4 ). The ground patterns are indicated by “ 13 G” in a collective numerical reference manner of the ground patterns  13 G 1  through  13 G 3 . This manner is applied to the signal patterns  13 S, the ground patterns  23 G, the signal patterns  23 S, the contacts  24 S and  245 G, the curved parts  25 S and  25 G, the head end parts  26 S and  26 G, and others. 
     The conductive patterns  13  are provided with gaps in the Y 1 -Y 2  direction in a manner where a pair of signal patterns is sandwiched by two ground patterns. For example, a pair of signal patterns  13 S 1  and  13 S 2  is provided between two ground patterns  13 G 1  and  13 G 2 . Similarly, a pair of signal patterns  13 S 3  and  13 S 4  is provided between two ground patterns  13 G 2  and  13 G 3 . 
     In addition, as shown in  FIG. 10 , the plug connector slice  20 SL, similar to the jack connector slice  10 SL, includes a conductive board  21 , an insulation layer  22 , and a conductive pattern  23 . The conductive board  21  has a plane plate shaped configuration and extends in X and Y directions. A pattern of the insulation layer  22  is formed at a Z 2  side of the conductive board  21 . A conductive pattern  23  is formed at a Z 2  side of the insulation layer  22 . 
     The conductive pattern  23 , similar to the conductive pattern  13  of the jack connector slice  10 SL, includes plural ground patterns  23 G ( 23 G 1  through  23 G 3 ) and signal patterns  23 S ( 23 S 1  through  23 S 4 ). 
     Furthermore, the conductive patterns  23  are provided with gaps in the Y 1 -Y 2  direction in a manner where a pair of signal patterns  23 S is sandwiched by two ground patterns  23 G. For example, a pair of signal patterns  23 S 1  and  23 S 2  is provided between two ground patterns  23 G 1  and  23 G 2 . Similarly, a pair of signal patterns  23 S 3  and  23 S 4  is provided between two ground patterns  23 G 2  and  23 G 3 . 
     In addition, the plug connector slice  20 SL includes plural contacts  24 . Each of the contacts  24  extends from an edge part at the X 2  side in the X 2  direction and has a bifurcated head end. The contact  24  functions as a plate spring. The contact  24  includes plural ground contacts  24 G ( 24 G 1  through  24 G 3 ) and plural signal contacts  24 S ( 24 S 1  through  24 S 4 ). 
     The contacts  24  are provided with gaps in the Y 1 -Y 2  direction in a manner where a pair of signal contacts  24 S is sandwiched by two ground contacts  24 G. For example, a pair of signal contacts  24 S 1  and  24 S 2  is provided between two ground contacts  24 G 1  and  24 G 2 . Similarly, a pair of signal contacts  24 S 3  and  24 S 4  is provided between two ground contacts  24 G 2  and  24 G 3 . 
     The conductive patterns  23  of the plug connector slice  20 SL are provided so as to be connected to the corresponding conductive patterns  13  of the jack connector slice  10 SL via the corresponding contacts  24 . Under the bifurcated head end structure of the contacts  24 , by improving flexibility and independent operability of the head end, contact between the conductive patterns  13  and the conductive patterns  23  can be secured. For example, even if the jack connector slice  10 SL or the plug connector slice  20 SL is deformed relative to the XY plane surface, as long as contact by at least one of the bifurcated head ends is secured, it is possible to maintain the connection between the conductive pattern  13  and the conductive pattern  23 . 
     If the jack connector slice  10 SL and the plug connector slice  20 SL are connected to each other, as shown in  FIG. 11 , the contact  24  makes a curved part  25  ( 25 G 1 ) projecting in the Z 2  direction contact the conductive pattern  13  ( 13 G 1 ) of the jack connector slice  10 SL 1  neighboring in the Z 2  direction, and makes a head end part  26  ( 26 G 1 ) projecting in the Z 2  direction and also Z 1  direction contact the conductive board  11  of the jack connector slice  10 SL 2  neighboring in the Z 2  direction. 
     In the contact  24 , an end part of the head end part  26  is bent in the Z 2  direction so as to project, and thereby the contact between the head end part  26  and the conductive board  11  of the jack connector slice  10 SL 2  is smoothly made. More specifically, while a designated angle (for example, approximately 30 degrees) is formed between the end part of the head end part  26  and the conductive board  11 , the end part of the head end part  26  projects in the Z 2  direction slightly (for example, approximately 0.6 mm). 
     As discussed below with reference to  FIG. 13 , between the end part of the head end part  26  and an inflection point of the curved part  25  of the contact  24  (a part where the conductive pattern  13  and the conductive pattern  23  come in contact with each other), the insulation layer  22  and the conductive pattern  23  are not provided but only the conductive board  21  is provided. 
       FIG. 12  is a view showing a connecting relationship between conductive patterns  13  of the jack connector slice  10 SL and conductive patterns  23  of the plug connector slice  20 SL. In  FIG. 12 , illustrations of the conductive board  11  and the insulation layer  12  of the jack connector slice  10 SL and the conductive board  21  and the insulation layer  22  of the plug connector slice  20 SL shown in  FIG. 11  are omitted. 
       FIG. 13  is a view of combinations of  FIG. 11  seen in various directions and shows the connecting relationship between neighboring two jack connector slices  10 SL 1  and  10 SL 2  and the plug connector slice  20 SL.  FIG. 13  includes a view seen in the V direction in  FIG. 11 , a cross-sectional view taken along a line C 1 -C 1 , a cross-sectional view taken along a line C 2 -C 2 , and a cross-sectional view taken along a line C 3 -C 3 . 
     The cross-sectional view taken along the line C 1 -C 1  shows a state where the ground pattern  23 G 1  of the plug connector slice  20 SL and the ground pattern  13 G 1  of the jack connector slice  10 SL 1  come in contact with each other at the curved part  25 G 1  of the ground contact  24 G 1  of the plug connector slice  20 SL, and the conductive board  21  of the plug connector slice  20 SL and the conductive board  11  of the jack connector slice  10 SL 2  come in contact with each other at the head end part  26 G 1  of the ground contact  24 G 1  of the plug connector slice  20 SL. The conductive board  21  of the plug connector slice  20 SL and the ground pattern  23 G 1  are connected to each other via vias  27   a  and the  27   b.    
     The cross-sectional view taken along the line C 2 -C 2  shows a state where the signal pattern  23 S 1  of the plug connector slice  20 SL and the signal pattern  13 S 1  of the jack connector slice  10 SL 1  come in contact with each other at the curved part  25 S 1  of the ground contact  24 S 1  of the plug connector slice  20 SL, and the conductive board  21  of the plug connector slice  20 SL and the conductive board  11  of the jack connector slice  10 SL 2  come in contact with each other at the head end part  26 S 1  of the signal contact  24 S 1  of the plug connector slice  20 SL. 
     As shown in the cross-sectional view taken along the line C 1 -C 1  and the cross-sectional view taken along the line C 2 -C 2 , between the end part of the head end part  26  of the contact  24  and an inflection point of the curved part  25  of the contact  24  (a part where the conductive pattern  13  and the conductive pattern  23  come in contact with each other), the insulation layer  22  and the conductive pattern  23  are not provided but only the conductive board  21  is provided. 
     The cross-sectional view taken along the line C 3 -C 3  shows a state where the conductive pattern  23  of the plug connector slice  20 SL and the conductive pattern  13  of the jack connector slice  10 SL 1  come in contact with each other at the curved part  25  of the contact  24  of the plug connector slice  20 SL, and the conductive board  21  of the plug connector slice  20 SL and the conductive board  11  of the jack connector slice  10 SL 2  come in contact with each other at the head end part  26  of the contact  24  of the plug connector slice  20 SL. 
     According to the above-discussed structure of the connector  100 , in a case where the jack connector slice  10 SL and the plug connector slice  20 SL are connected to each other, the head end part  26 S of the signal contact  24 S of the plug connector slice  20 SL comes in contact with the conductive board  11  of the jack connector slice  10 SL. It is possible to prevent the signal contact  24 S from functioning as an unnecessary long ground stub. 
     In the connector  100 , the head end part  26 S of the signal contact  24 S of the plug connector slice  20 SL positioned in a most deep layer in the Z 1  direction (eighth layer seen from the Z 2  side) is made to come in contact with an independent conductive plate, instead of the conductive board  11  of the jack connector slice  10 SL. This is because the plug connector slice  20 SL is not provided in the SZ 1  direction and there is no need to arrange the jack connector slice  10 SL. 
     Here, a reduction effect of insertion loss of the connector  100  due to a configuration of the contact  24  is discussed with reference to  FIG. 14 .  FIG. 14(A)  is a graph showing transition (simulation result) of the insertion loss relative to a signal frequency of the connector wherein a frequency [GHz] of a signal passing through the conductive pattern  13  and the conductive pattern  23  is indicated at a horizontal axis and the insertion loss [dB] is indicated at a vertical axis. Three curves CV 1  through CV 3  corresponding to contact configurations of three kinds of the connectors are indicated in this graph. 
     In addition,  FIG. 14(B)  is a view corresponding to the C 2 -C 2  cross-sectional view in  FIG. 13  and shows a contact configuration of the connector providing the curve CV 1 . Similarly,  FIG. 14(C)  shows a contact configuration of the connector providing the curve CV 2 .  FIG. 14(D)  shows a contact configuration of the connector providing the curve CV 3 . The contact configuration of the connector  100  corresponds to the contact configuration of the connector shown in  FIG. 14(D) . 
     In the contact configuration of the connector shown in  FIG. 14(B)  and  FIG. 14(C) , the signal contact  24 S of the plug connector slice  20 SL does not come in contact with the conductive board  11  of the neighboring jack connector slice  10 SL 2 . Therefore, the ground stubs GS 1  and GS 2  having lengths indicated by a dotted area are formed. 
     As a result of this, as shown in  FIG. 14(A) , in the curve CV 1  caused by a structure shown in  FIG. 14(B)  forming a relatively long ground stub GS 1 , compared to the curve CV 2  caused by a structure shown in  FIG. 14(C)  forming a relatively short ground stub GS 2 , a peak of the insertion loss is formed at lower frequency band. While a peak of the insertion loss of the curve CV 1  is in the vicinity of 12 GHz, a peak of the insertion loss of the curve CV 2  is in the vicinity of 14 GHz. 
     On the other hand, as shown in  FIG. 14(D) , the signal contact  24 S of the plug connector slice  20 SL of the connector  100  comes in contact with the conductive board  11  of the neighboring jack connector slice  10 SL 2 . Therefore, a long ground stub having a contact configuration shown in  FIG. 14(B)  and  FIG. 14(C)  is not formed. An extremely short ground stub GS 3  and an extremely short stub (hereinafter “signal stub”) SS 1  indicated by a dotted line in  FIG. 14(D)  are formed. 
     The ground stub GS 3  and the signal stub SS 1  are much shorter than the ground stubs GS 1  and GS 2  of the connector shown in  FIG. 14(B)  and  FIG. 14(C) . As a result of this, as shown in  FIG. 14(A) , in the curve CV 3  caused by a structure shown in  FIG. 14(C) , compared to the curve CV 1  caused by a structure shown in  FIG. 14(B)  forming a relatively long ground stub GS 1  and the curve CV 2  caused by a structure shown in  FIG. 14(C)  forming a relatively long ground stub GS 2 , a peak of the insertion loss is formed at higher frequency band (in the vicinity of 20 GHz). 
     The signal stub SS 1  is much shorter than the ground stubs GS 1  and GS 2  in the contact configuration shown in  FIG. 14(B)  and  FIG. 14(C) . Therefore, although it is not clearly shown in  FIG. 14(B)  and  FIG. 14(C) , the signal stub SS 1  is provided in the connectors shown in  FIG. 14(B)  and  FIG. 14(C) . 
     According to the above-discussed structure of the connector  100 , in a case where the jack connector slice  10 SL and the plug connector slice  20 SL are connected to each other, the signal contact  24 S is prevented from functioning as an unnecessarily long ground stub. A peak of the insertion loss can be moved to the high frequency side and signal transmission at higher frequency bands can be made. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority or inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention. 
     For example, in the above-discussed embodiment, the jack connector slice  10 SL and the plug connector slice  20 SL are formed of the rigid boards. However, the jack connector slice  10 SL and the plug connector slice  20 SL may be formed of a flexible print board or a rigid flexible board. 
     In the above-discussed embodiment, the jack connector slice  10 SL has a three layer structure formed of the conductive board  11 , the insulation layer  12 , and the conductive pattern  13 . The jack connector slice  10 SL may have a structure where an independent conductive board  11  and a board having a two layer structure formed of the insulation layer  12  and the conductive pattern  13  are separately provided. In this case, a gap may be formed in the thickness direction between the independent conductive board  11  and the board having the two layer structure, and the plug connector slice  20 SL may be inserted in the gap. 
     In this case, when the jack connector slice  10 SL and the plug connector slice  20 SL are connected to each other, the connector  100  makes each of the conductive patterns  23  of the plug connector slice  20 SL and the corresponding conductive patterns  13  of the jack connector slice  10 SL come in contact with each other at corresponding parts of the curved parts  25  of the contacts  24  of the plug connector slice  20 SL. Furthermore, the connector  100  makes the conductive board  21  of the plug connector slice  20 SL and the independent conductive board  11  of the jack connector slice  10 SL come in contact with each other at the head end part  26  of the contact  24  of the plug connector slice  20 SL. The independent conductive board  11  may have a plate-shaped configuration or a pin-shaped configuration. 
     In this embodiment, the conductive board  11  of the jack connector slice  10 SL has a size covering an entire surface of the jack connector slice  10 SL. However, the conductive board  11  of the jack connector slice  10 SL may have a size smaller than a surface of the jack connector slice  10 SL, as long as the contacts  24  do not function as stubs obstructing the transmission of a signal having a predetermined frequency in a case where the jack connector slice  10 SL and the plug connector slice  20 SL are connected to each other and the head end parts  26  of the contacts  24  of the plug connector slice  20 SL come in contact with the conductive board  11 .