Abstract:
An electrical connector is to be connected to a mating connector. The electrical connector includes a circuit board member formed of an insulation plate member; and a holding member for holding the circuit board member. The circuit board member includes a connecting portion to be connected with a mating connector of the mating connector. The connecting portion includes a pair of conductive band portions and a first insulation region disposed between the conductive band portions.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to an electrical connector, in which a flat circuit board such as a circuit board member having a board circuit configuration is held with a holding member. In particular, the present invention relates to an electrical connector, in which a flat circuit board such as a circuit board member having a board circuit configuration suitable for high-speed transmission is held with a holding member. 
     As a conventional board circuit configuration in a circuit member of a connector of this type, for example, there is known a conventional circuit configuration disclosed in Patent Reference. The conventional circuit configuration of Patent Reference 1 is the most common and simple configuration, and has a plurality of transmission paths only on one surface of the circuit board and a grounding plate all over the other surface thereof by plating, without having transmission paths in an inner layer of the circuit board. 
     Patent Reference: U.S. Patent Application Publication No. 2012-0295453A1 
     In the conventional circuit configuration disclosed in Patent Reference, a plurality of transmission paths corresponds and is electrically connected to a plurality of pad-like connecting sections arranged along an edge of the circuit board. Each transmission path has a smaller width (a dimension in a direction of the arrangement) than that of the corresponding connecting section. The plurality of transmission paths is arranged so as to repeat the arrangement such as that of one grounding transmission path, two adjacent signal transmission paths, and one grounding transmission path. One grounding transmission path is provided each of both sides of two signal transmission paths that compose a pair of transmission paths. 
     In the conventional circuit configuration disclosed in Patent Reference, the grounding transmission paths are electrically connected to the grounding plate on the other surface with via holes penetrating through the board. In the pair of transmission paths, the transmission paths are close to each other in the width direction, and the both are connected to corresponding connecting sections of paired connecting sections, and form a pair of transmission paths suitable for transmitting high-speed signals. The pair of connecting sections that is electrically connected to the pair of transmission paths increases the distance in the width direction between the both connecting sections of the pair of connecting sections so as to have large width as described above in order to adjust impedance, corresponding to a thickness of the board defined by itself. 
     In the conventional circuit configuration disclosed in Patent Reference, however, when the connecting sections have large areas with large width, the distance between the both connecting sections in the width direction is increased. Therefore, although it is possible to adjust and improve the impedance, there are issues as follows. 
     First, since the connecting sections have a large area, when all of the connecting sections are formed on a circuit board surface by plating, a total plating area has to be increased, which results in higher cost. 
     Second, the respective connecting sections have a large areas, so that it is possible to fully cover points of contacts with mating terminals. Therefore, even if there is some relative displacement among the contacts in the width direction, since the range of the contacts is large, it is advantageous in view of secure contacts. However, the contact surface pressure has to be small, and thereby there is an issue of lower contact reliability. 
     In view of the problems described above, an object of the present invention is to provide an electrical connector having a circuit member, which can restrain the plating area as small as possible and achieve high contact reliability under high contact surface pressure, while securing the distance between connecting sections, impedance of which is adjustable. 
     Further objects and advantages of the present invention will be apparent from the following description of the present invention. 
     SUMMARY OF THE PRESENT INVENTION 
     According to a first aspect of the present invention, an electrical connector holds circuit members arranged therein by a holding member. Each circuit member is flat and made of an electrically insulating material and has a plurality of connecting sections that are made of a conductive material, provided only on one surface thereof, and electrically connected corresponding to the respective transmission paths. The connecting sections are arranged along edges of each circuit member so as to be capable of contacting with contact terminals of mating connecting member. The width of each connecting section is set larger than the width of each transmission path. Here, the circuit member includes a typical circuit board to be attached alone in an electrical device as well as a blade molded in a specified shape to be mounted and held in a connector, and may include any circuit members, e.g., a flat circuit board having transmission paths formed thereon and pad-like connecting sections, which are electrically connected to the transmission paths and formed and arranged at edges of the circuit member. The connecting sections are formed by directly plating on the circuit board or by providing a sheet metal layer as terminal sections and then plating the sheet metal layer on the circuit board. In either method, formation of the connecting sections includes plating. 
     According to the first aspect of the present invention, in the electrical connector, the connecting sections are formed having conductive thin sections made of a conductive material at least at both outer edges of the connecting sections in a width direction. Between the conductive thin sections at the both outer edges, insulating areas where there is no conductive material are provided at the same surface level or recessed from the surface level of the conductive thin sections. 
     According to the first aspect of the present invention, while the connecting sections keep a suitable distance between centerlines thereof according to a thickness of the circuit member such as a circuit board for adjustment of impedance, the insulating areas are provided, and conductive members are provided on both sides of the insulating areas. Therefore, it is possible to significantly reduce the area of the connecting sections at the conductive thin sections. In addition, it is possible to reduce the total plating area as the connecting sections, so that it is possible to reduce the cost for plating. Moreover, increasing the contact surface pressure to contact terminals, which are corresponding parts to the conductive thin sections, it is possible to improve the contact reliability. Furthermore, it is possible to increase allowable displacement in the width direction due to increase in the number of contact points. According to the first aspect of the present invention, it is effective when the transmission paths are paired transmission paths for high-speed signal transmission, but even when the transmission paths are not paired transmission paths but general transmission paths, it is still similarly effective in view of reduction of plating cost. 
     According to a second aspect of the present invention, the conductive thin sections of the connecting sections formed on each circuit member can be also provided in the middle between the outer edges. In other words, it is also possible to add another conductive thin section. As such, it is possible to increase the allowable displacement in the width direction. 
     According to a third aspect of the present invention, each connecting sections formed on each circuit member is preferably formed in a frame-like shape with conducting thin sections and a joining thin section. With this configuration, any conductive thin sections form closed path (closed loop) connecting to the transmission path without end, so that it is possible to enhance the strength without an issue of peeling ends from a surface of the circuit board member. 
     According to a fourth aspect of the present invention, each circuit member has a plurality of transmission paths that form pairs of transmission paths on one surface thereof and have on the other surface thereof a grounding plate that is formed by plating and covers range where the transmission paths are arranged. The grounding plate has ground connecting sections that can contact with ground contact terminals of mating connecting member in the range of the other surface corresponding to the range where connecting sections of the transmission paths are arranged. In the ground connecting sections, parts corresponding to the insulating areas between the conductive thin sections on the one surface are insulating areas where there is no conductive material. With this configuration, it is possible to form insulating areas at corresponding plurality of areas on both surfaces of the circuit board and it is possible to reduce the plating area as a whole. 
     As described above, according to the present invention, while the distance between centerlines of the connecting sections at edges of circuit members electrically connected to transmission paths is kept at suitable value based on a thickness of a circuit member suitable for high-speed signal transmission, the connecting sections are formed by conductive thin sections on the both outer side edges, and there are provided insulating areas therebetween. With this configuration, it is possible to reduce the total plating area for connecting sections by reducing the areas of connecting sections, and increase the contact surface pressure to mating contact terminals at conductive thin sections that have small areas. As a result, there is an effect of improved contact reliability. Furthermore, as one connecting section, at both outer side edges, i.e., at least two conductive thin sections are present in the width direction, so that the width to displacement of points to contact with mating contact terminals is enlarged. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a connector assembled component, in which an electrical connector, an upper mating connector thereof, and a lower mating connector thereof are fitted to assemble according to an embodiment of the present invention; 
         FIG. 2  is a perspective view showing the connector assembled component before fitting the electrical connector to the upper and lower mating connectors according to the embodiment of the present invention; 
         FIG. 3  is a perspective view showing a circuit board used in the electrical connector according to the embodiment of the present invention; 
         FIG. 4  is a view showing a substrate main body (with electric elements) of the circuit board in a state that a protective cover is removed from the circuit board according to the embodiment of the present invention; 
         FIG. 5  is a detailed view showing one surface of the substrate main body of the circuit board in a state that the electric elements are removed according to the embodiment of the present invention; 
         FIG. 6  is a detailed view showing the other surface of the substrate main body of the circuit board according to the embodiment of the present invention; 
         FIG. 7  is an enlarged view showing a part of connecting sections and surrounding area thereof of the circuit board according to the embodiment of the present invention; and 
         FIG. 8  is a sectional view showing the connecting sections and the surrounding area thereof of the circuit board taken along a line VIII-VIII in  FIG. 7  according to the embodiment, of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereunder, an embodiment of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a perspective view showing a state after assembling of a connector assembled component I composed of a connector  10  according to the embodiment, which hold circuit members having transmission paths formed thereon, and mating connectors  50  and  60  that are mating connecting members connected to the connector  10  from thereabove and thereunder, respectively. Both of the mating connectors  50  and  60  hold bottom plates  52  and  62 , on which terminals are mounted. Connecting the mating connectors  50  and  60  to the connector  10  from thereabove and thereunder, the two bottom plates  52  are connected via the connector  10 . On the other hand, upon use, one mating connector  60  is attached onto a circuit board (not illustrated) provided under the connector  10 , and the other mating connector  50  is attached to a circuit board (not illustrated) provided above the connector  10 . The forms of the mating connectors are identical to each other. 
     In the embodiment of the present invention, the circuit members held in the connector  10  include general types of circuit boards to be attached alone to electronic devices, as well as blades or the like that are molded in certain shapes and mounted in connectors, i.e., any circuit members, in which pad-type connecting sections connected to transmission paths are arranged and formed at edges of the circuit members for electrical connection to other members. 
     As described above, since the mating connectors  50  and  60  are identical to each other, only the mating connector  50  provided above the connector  10  will be described in  FIGS. 1 and 2 . Explanation of the other mating connector  60  provided under the connector  10  will be omitted, and reference numeral in 60&#39;s, which are the number  10  is added to respective reference numerals for corresponding parts of the mating connector  50 , will be used for common parts with those of the mating connector  50  when explanation is necessary. 
     As shown in  FIG. 2 , the mating connector  50  has two bottom plates  52  and  52  attached on an outer surface of the bottom plate side (an upper side of the bottom plate  52  in  FIG. 1 ) of the quadrilateral frame-like shaped connector main body  51  made of insulating material. On those bottom plates  52 , contact terminals penetrating through the bottom plates  52  in a plate&#39;s thickness direction are arranged in columns and rows. On a bottom surface side of the bottom plates  52 , solder balls  53  are applied on the contact terminals and the contact terminals protrude downward from the bottom plates  52  in the connector main body  51 . 
     In the embodiment, the contact terminals have at their ends (lower ends) contact sections (not illustrated) that elastically contact with surfaces of the circuit boards of the connector  10 , which will be described later. The contact terminals of the mating connector  50  are arranged being a mix of signal terminals and grounding terminals. The contact sections of the signal terminals elastically contact with the connecting sections for transmission paths formed on one surface of each circuit board of the connector  10 , and the contact sections of the grounding terminals elastically contact with grounding connecting sections formed on the other surface thereof, respectively. 
     In the embodiment, the signal terminals and the grounding terminals are arranged being staggered at half pitch intervals in the arrangement direction, and the signal terminals and the grounding terminals contact at the staggered positions on the one surface and the other surface of each circuit board of the connector  10 . 
     An outer circumferential surface of the connector main body  51  of the mating connector  50  forms a surface to be guided upon fitting to the connector  10 , and has protrusions to be guided  51 A and  51 B at the four corners thereof. At a left end surface in the figure, there is provided a key protrusion  51 C, which has a shape that looks like a key, so as to prevent a fitting error in a left-and-right direction. Here, in order to securely prevent fitting errors, the protrusions to be guided  51 A and  51 B also have different shapes. Moreover, on an outer side surface of the connector main body  51 , there is provided a locking protrusion  51 D for fitting and locking the mating connector  50  to the connector  10 . 
     The mating connector  50  formed as described above (which is also the same in the mating connector  60 ) is not main idea of the present invention. The explanation of the mating connector  50  is simply given as a mating connector to connect to the connector  10  of the present invention, which will foe described below, and further explanation will be omitted. 
     The connector  10  is formed as one connector, joining an upper connector  20  and a lower connector  30 . The upper connector  20  includes an upper case  21  made of an insulating material and the lower connector  30  includes a lower case  31  made of an insulating material. Fitting the upper case  21  and the lower case  31  to each other from above and below respectively, a housing  11 , which is a quadrilateral tube-like case, is formed. The housing  11  works as a holding member to hold circuit boards (described later). 
     Both the upper case  21  and the lower case  31  are opened in an up-and-down direction, penetrating perpendicularly. The housing  11  in a state that the both cases  21  and  31  are fitted and joined holds circuit boards that extend in a height direction in the both upper and lower cases  21  and  31 . Each circuit board  40  has a dimension of the height of the housing  11  and a plurality of the circuit boards  40  are held in the housing  11  in rows. 
     The housing  11  having a shape of a quadrilateral tube-like case has a size and shape, such that inner surfaces of the upper and lower openings thereof can receive and fit to the mating connectors  50  and  60 . On an inner circumferential surface of the housing  11 , there are also provided locking step-like sections (not illustrated) to prevent the housing  11  from coming off from the mating connector  50  by locking to the locking protrusions  51 D of the mating connector  50 . 
     In the embodiment, the mating connector  60  provided thereunder also has on an inner circumferential surface thereof locking step-like sections that lock to the locking step-like sections  61 D of the mating connector  60 . The housing  11  itself is not a main idea of the present invention. As for the housing  11 , since brief explanation is enough as long as it can be understood that the housing  11  serves to arrange and hold a plurality of circuit board  40  at positions so as to be capable of connecting to contact terminals of the mating connectors  50  and  60 , and further explanation will be omitted. 
     As shown in  FIG. 2 , a plurality of the circuit boards  40  arranged and held in the housing  11  is arranged at constant, intervals in a longitudinal direction of the housing  11 . Each circuit board  40  extends in the up-and-down direction and has contact sections at its respective upper and lower edges to electrically connect to the mating connectors  50  and  60 . 
     Each circuit board  40  has an outer shape as shown in  FIG. 3 , and includes a flat board main body  41 , electrical elements  47 , and a protective cover  48 . The board main body  41  includes transmission paths  43  for signal transmission, connecting sections  44 , and grounding paths  45 , which are provided on one surface of a base material board  42  made of an electrically insulating material, and grounding plates  46  provided on the other surface (described in  FIG. 6 ), which are respectively plated on the base material board  42 . The electrical elements  47  are attached to paired transmission paths  43  and will, be described later. 
       FIG. 4  is a schematic view of the one surface of the board main body  41  showing the paired transmission paths  43  for signals and connecting sections  44 , which are provide by plating, and electrical elements  47  connected, to the transmission paths  43  and the grounding paths  45 .  FIG. 5  is a detailed view of one surface of the board main body  41  before connecting the electrical elements  47  thereto, and  FIG. 6  is a view showing the other surface of the board main body  41 . 
     As shown in  FIG. 5 , each pair of the paired transmission paths  45  for signals are composed of two transmission paths  43 A and  43 B, forming a pair at adjacent positions and extending in an up-and-down direction. In the example of  FIG. 5 , there are provided five pairs of the paired transmission paths  43  at intervals in the board&#39;s width direction (lateral direction). 
     As shown in  FIG. 5 , the paired transmission paths  43  are provided being separated into an upper part and a lower part, but as shown in  FIG. 6  that shows the other surface of the board main body  41 , the both surfaces of the board main body  41  are electrically connected to each other through via holes (which are small holes penetrating the both surfaces of the board main body for electrical connection and not illustrated in the figure), which are formed on pads  43 A- 2  and  43 B- 2 , respectively. In the up-and-down direction, the paired transmission paths continuously extend to near the upper edge and lower edge of the board main body  41 . 
     Here, since illustration of the electrical elements  47  is omitted in  FIG. 5 , the transmission paths  43 A and  43 B on the upper part seem to be discontinuous at the lower end, but are electrically connected by the electrical elements  47  as shown in  FIG. 4 . In  FIG. 5 , the above-described five pairs of transmission paths  43  have pads  43 A- 1 U and  43 B- 1 U and pads  43 A- 1 L and  43 B- 1 L, on which the via holes are formed at positions so as to be separated at middle position in the up-and-down direction. 
     As described above, through the respective via holes, and via the pads  43 A- 2  and  43 B- 2  on the other surface, the upper part and the lower part of each transmission path  43  forms one continuous transmission path. Here, in those five pairs of transmission paths  43 , there are differences among positions of the pads  43 A- 1 U,  43 B- 1 U;  43 A- 1 L,  43 B- 1 L;  43 A- 2 ,  43 B- 2 . These differences are based on that straight pairs and crossed pairs are alternately arranged within the plate&#39;s thickness direction of the board main body  41 , in order to reduce crosstalk between adjacent differential pairs, on the five differential pair line, so as to form a differential pair line having two transmission lines as a pair for a purpose of high-speed signal transmission and noise reduction. 
     The two transmission paths  43 A and  43 B of the paired transmission paths  43  that form a pair are electrically connected to the connecting sections  44  ( 44 A and  44 B) provided being plated in a pair on the upper edge and the lower edge of the board main body  41 . The transmission paths  43 A and  43 B are adjacent to each other in the up-and-down direction with very short intervals between the connecting sections  44  and the pads  43 A- 1 U,  43 B- 1 U;  43 A- 1 L,  43 B- 1 L, and have large intervals only at positions communicating with the connecting sections  44  and transitional range for communication with the pads  43 A- 1 U,  43 B- 1 U;  43 A- 1 L,  433 - 1 L. The connecting sections  44  are the main idea of the present invention and will be fully described below. 
     As shown in  FIG. 5 , being plated on one surface of the board main body  41 , there are grounding paths  45  that are continuous in the up-and-down direction between pairs of the paired transmission paths  43  and on both side edges of the board main body  41 . More specifically, the grounding paths  45  are provided on both sides of each pair of the transmission paths  43  so as to have a pair of the transmission paths  43  therebetween. On each grounding path  45 , there is provided a plurality of via holes  45 A for connecting to grounding plate  46 , which is provided on the other surface of the board main body  41  and will be described later. In  FIG. 5 , within the range of the grounding paths  45 , there are formed circular through holes  41 B formed near the pads  43 A- 1 U and  43 B- 1 U penetrating the board main body  41  in the plate&#39;s thickness direction. Those circular through holes  41 B are used for attaching the protective cover  48  shown in  FIG. 4  on the board main body  41 . 
     As shown in  FIG. 3 , the protective cover  48  is provided on the board main body  41  at the middle part thereof in the up-and-down direction. The protective cover  48  is formed like a lid that covers where the pads  43 A- 1 U,  43 B- 1 U;  43 A- 1 L are present. The protective cover  48  is made of an insulating material, and as shown in  FIG. 3 , has a flat section  48 A that faces the one surface of the board main body  41  and side plate sections  48 B and  48 C on the both sides, and is formed as a thin lid. 
     On the flat plate section  48 A of the protective cover  48 , there are formed widow sections  48 A- 1  so as not to contact to press the electric elements  47  attached on the transmission paths of the board main body  41 . Furthermore, on the flat plate section  48 A, there is integrally formed a protective strip section  48 A- 2  that is lifted so as to be away from the surface of the board main body  41  and extends in a lateral direction so as to protect the window sections  48 A- 1 . On the side plate section  48 B and the side plate section  48 C, there are formed notches  48 C- 1  and  48 C- 2  for protrusions  41 A to protrude, which are provided on the side edges of the board main body  41  and will be described later. The side plate section  48 B provided on the left side has a step-like thin section so as to have a larger thickness than the side plate section  48 C provided on the right side. 
     When each circuit board  40  is inserted to be disposed in a specified insertion groove formed on inner walls of the housing  11 , the protective cover  48  is guided to be inserted in the insertion groove. At this point, since the thicknesses are different, it is possible to have the left edge and the right edge inserted in correct orientation. After inserting the above-described short circular cylinder-like bosses, which protrude from the flat plate section  43 A, in the above-described through holes  41 B, the bosses are softened by ultrasonic welding or by other method so as to close the through holes  41 B. The, as the bosses become hardened as temperature is lowered, the protective cover  48  is secured on the board main body  41 . 
     As shown in  FIGS. 3 to 5 , on the board main body  41 , there is formed a plurality of protrusions on the both side edges. The plurality of protrusions is provided so as to protrude from the notches  48 C- 1  and  48 C- 2  of the protective cover  48  for positioning of the circuit board  40  in the housing  11 . The protrusions  41 A, which are small and provided at a center in the height direction and protrude more than other protrusions, are protrusions to be tightly held by the upper case  21  and the lower case  31  that form the housing  11  and for positioning and being held. 
     Next, the connecting sections  44 , that is the main feature of the present invention, will be described. The connecting sections  44  are arranged and formed being plated on the upper edge and the lower edge of each board main body  41 , and are connected to upper ends and lower ends of the paired transmission paths  43 .  FIG. 7  is an enlarged view near two connecting sections  44  ( 44 A and  44 B) provided on the right lower edge of the circuit board  40  in  FIG. 4 , corresponding to one pair of the transmission paths  43  (transmission path  43 A and transmission path  43 B). 
     As shown in  FIG. 7 , the two transmission paths  43 A and  43 B are respectively arranged side by side being close to each other in the width direction (in a left-and-right direction in the figure). At their lower ends, while slightly increasing the width of the transmission path itself, the distance between the transmission paths  43 A and  43 B is increased. On the both sides of the pair of transmission paths  43 , there are provided the grounding paths  45 . 
     The relation between the distance d 1  between centerlines L 1 A and L 1 B of the transmission paths  43 A and  43 B that go through centers in width&#39;s directions and the distance d 2  between centerlines L 2 A and L 2 B of the connecting sections  44 A and  44 B that correspond to the transmission paths  43 A and  43 B is d 2 &gt;d 1 . The ratio between d 2  and d 1  in the relation is suitably set according to a thickness of the board main body  41  so as to adjust impedance. As described above, the relation d 2 &gt;d 1  is achieved by increasing the width itself, i.e., the distance therebetween in the transitional area from the transmission paths  43 A and  43 B to the connecting sections  44 A and  44 B. 
     All the connecting sections  44 A and  44 B are formed to have frame-like shapes. More specifically, any of the connecting sections  44 A and  44 B has conductive thin sections  44 A- 1  and  44 B- 1  made of a conductive material on both side edges in their width directions. The both conductive thin sections  44 A- 1  and  44 B- 1  are joined at their lower ends with joining thin sections  44 A- 2  and  44 B- 2 , respectively, and with the transmission paths  43 A;  43 B, quadrilateral frame-like shapes are made. 
     In the embodiment, the distance b 2  between the both conductive thin sections  44 A- 1  (which will be also the same for the distance between both conductive thin sections  44 B- 1 ) is larger than the width b 1  of the corresponding transmission path  43 A. According to the embodiment, however, the width b 3  of one conductive thin section  44 A- 1  is smaller than the width b 1  of the transmission path  43 A. The strip widths (a dimension in a height direction in  FIG. 7 ) of the joining thin sections  44 A- 2  and  44 B- 2  are not limited by the relation with the widths b 1 , b 2 , and b 3 , but are preferably close to b 3 . 
     Accordingly, the connecting sections  44 A and  44 B are formed by the both conductive thin sections  44 A- 1 , conductive thin sections  44 B- 1 , and joining thin sections  44 A- 2  and  44 B- 2 . According to the present invention, the connecting sections  44 A and  44 B essentially require presence of the both conductive thin sections  44 A- 1  and the both conductive thin sections  44 B- 1 , but the joining thin sections  44 A- 2  and  44 B- 2  are not essential, and the both conductive thin sections  44 A- 1  do not have to be joined at their lower ends. However, in order to enhance the holding strength of the both conductive thin sections  44 A- 1  and  44 B- 1  by the board main body  1 , it is preferred to have the joining sections  44 A- 2  and  44 B- 2  present. For the same reason, the both conductive thin sections  44 B- 1  are preferably joined with the joining section  44 B- 2 . 
     In the connecting sections  44 A and  44 B formed in frame-like shape, the areas surrounded by the frames are a surface of the base material board  42  itself of the board main body  41 , and are insulating areas  42 A and  42 B. As shown in  FIG. 8 , which is a sectional view taken along a line VIII-VIII of  FIG. 7 , the insulating areas  42 A and  42 B are recessed, relative to the conductive thin sections  44 A- 1  and  44 B- 1 . Therefore, when the contact terminals of the mating connecting member contact with the connecting sections  44 A and  44 B with elastic pressure in the thickness direction of the board main body  41 , it is possible to securely contact with the conductive thin sections  44 A- 1  and  44 B- 1 . 
     In addition, at this point, the contact areas of the conductive thin sections  44 A- 1  and  44 B- 1  to the contract terminals of the mating connecting member are smaller due to the presence of the insulating areas  42 A and  42 B, and the contact pressure is enhanced and the contact reliability is improved. At the same time, it is possible to reduce the total plating area upon forming all the connecting sections, and thereby it is possible to reduce the cost for plating. Here, surface levels of the insulating areas  42 A and  42 B can be at the same as or close to the surface level of the conductive thin sections  44 A- 1  and  44 B- 1 , unless the contact between the conductive thin sections  44 A- 1  and  44 B- 1  and the contact terminals of the mating connecting material is not inhibited, or unless the contact pressure is not reduced to be less than a suitable value. 
     According to the embodiment, the connecting sections  44 A and  44 B have conductive thin sections  44 A- 1  and  44 B- 1  only on the both sides, but it is also possible to provide another conductive thin section in the middle, for example, so as to have three conductive thin sections disposed in rows present. Even in this case, it is preferred to join the middle conductive thin sections to the joining thin sections  44 A- 2  and  44 B- 2 . 
     As described above, the board main body  41  has paired transmission paths  43 , etc. on one surface and has the grounding plate  46  on the other surface as shown in  FIG. 6 . Similarly to the paired transmission paths  43 , etc., the grounding plate  46  is formed being plated on the base material board  42  of the board main body  41 , and extend all over the surface of the base material board  42  except, very limited excluded area. The excluded area where grounding plate  46  is not formed includes narrow areas at peripheral edges on the base material board  42  that does not require shielding, areas where the pads  43 A- 2  and  43 B- 2  exist, through holes  41 B for securing the protective cover  48 , and a limited area in the ground connecting sections, which will be described later. 
     The grounding plate  46  is provided on the other surface of the board main board  41  in the range corresponding to the range that covers in the up-and-down direction and the width direction the area where the plurality of connecting sections  44  is present for the paired transmission paths  43  formed on one surface of the board main body  41  in  FIG. 5 . In addition, the grounding plate  46  has ground connecting sections  49 . 
     As shown in  FIG. 6 , each ground connecting section  49  has a generally comb&#39;s teeth-like shape, so as to alternately have an area grounding plate  46  is present and an area grounding plate is not present. As shown in the sectional view taken along the line VIII-VIII of  FIG. 8 , the ground connecting section  49  is provided so as to alternately have a wide part  49 A for contacting with ground contacting terminals of the mating connecting member and a narrow part  49 B. 
     As shown in  FIG. 8 , the wide parts  49 A are provided so as to be staggered on the other surface of the board main body  41  relative to the connecting sections  44  ( 44 A and  44 B) formed on the one surface of the board main body  41 . For example, in  FIG. 8 , the wide part  49 A provided at the center is provided in the range where the conductive thin section  44 A- 1 ( 2 ) on the right side in the two conductive thin sections  44 A- 1 ( 1 ) and  44 A- 1 ( 2 ) of the connecting section  44 A and the conductive thin section  44 B- 1 ( 1 ) on the left side in the two conductive thin sections  44 B- 1 ( 1 ) and  44 B- 1 ( 2 ) of the connecting section  44 B. 
     The narrow sections  49 B are provided so as to correspond to the conductive thin section  44 A- 1 ( 1 ) on the left, side in the conductive thin sections  44 A- 1 ( 1 ) and  44 A- 1 ( 2 ) of the connecting section  44 A and the conductive thin section  44 B- 1 ( 2 ) on the right side in the two conductive thin sections  44 B- 1 ( 1 ) and  44 B- 1 ( 2 ) of the connecting section  44 B, respectively, and work as shielding against the conductive thin sections  44 A- 1  and  44 B- 1 . 
     Therefore, the narrow parts  49 B do not serve for contacting with the ground contact terminals of the mating connecting member. Between the wide parts  49 A and the narrow parts  49 B, there is no ground connecting sections  49  and form insulating areas  49 C, corresponding to the insulating areas  42 A and  42 B of the connecting sections  44  in the width direction. While providing narrow parts  49 B that work for shielding, by providing the insulating areas  49 C, it is possible to reduce the plated areas as a whole upon forming the grounding plate  46  by plating. 
     The disclosure of Japanese Patent Applications No. 2013-163326, filed on Aug. 6, 2013, is incorporated in the application by reference. 
     While the present invention has been explained with reference to the specific embodiments of the present invention, the explanation is illustrative and the present invention is limited only by the appended claims.