Patent Publication Number: US-10763604-B2

Title: Plug, receptacle, and connector

Description:
TECHNICAL FIELD 
     The present invention relates to a connector, and especially relates to configurations of a plug and a receptacle that are mated with each other to constitute the connector. 
     BACKGROUND ART 
     Japanese Patent Application Laid Open No. 2009-230945 (published on Oct. 8, 2009, referred to as Literature 1 below) describes a connector including a plug and a receptacle.  FIG. 1  illustrates the configuration of the plug described in Literature 1. 
     The plug includes a plurality of plug contacts  11  and a block  12 . The plug contact  11  includes a contact portion  11   a  that comes into contact with a mating receptacle contact, a fixed portion (hidden and not seen in  FIG. 1 ) that is fixed to the block  12 , and a connection portion  11   b  that is connected to a board. 
     The plug contacts  11  are mounted such that the fixed portions are press-fitted to insertion holes (hidden and not seen in  FIG. 1 ) of the block  12  and a required number of plug contacts  11  are aligned and held in the block  12 . 
     SUMMARY OF THE INVENTION 
     As illustrated in  FIG. 1 , contact parts of pin contacts (plug contacts) are aligned with gaps interposed therebetween in an alignment direction of the pin contacts in a plug of related art. This brings a state that a part of a socket contact and a corner portion of an insulator, holding the socket contacts, for example, of a receptacle are fitted between pin contacts in a mating operation with respect to the receptacle. Thus, there have been a problem that mating operability is poor and a problem that pin contacts and socket contacts are deformed or damaged. 
     An object of the present invention is to provide a plug that prevents a part of a socket contact and a corner portion of a receptacle insulator, for example, of a receptacle from fitting between pin contacts, accordingly provides favorable mating operability, and thus can prevent deformation and damages of pin contacts and socket contacts. In addition to this, an object of the present invention is to provide a receptacle for mating with the plug and a connector that is composed of the plug and the receptacle. 
     According to the present invention, a plug for mating with a receptacle includes: an insulator that has an inner bottom surface, which is orthogonal to a mating direction of the plug; and a plurality of pin contacts secured to the insulator and aligned in an alignment direction, each of which includes a contact tab having a pair of planar surfaces of the contact tab on two mutually opposite sides thereof which are parallel to each other, the planar surface of the contact tab each forming a contact surface. The contact tabs stand up from the inner bottom surface in the mating direction, the contact surfaces being parallel to the alignment direction. A plurality of protrusions are formed in the insulator that stand up from the inner bottom surface in the mating direction, such that each of the protrusions is positioned between two of the contact tabs which are next to each other in the alignment direction. 
     According to the present invention, a receptacle for mating with a plug in a mating direction includes: a receptacle insulator; and a plurality of socket contacts that are secured to the receptacle insulator and aligned in a socket alignment direction. Each of the socket contacts includes a contact portion, a coupling portion, a spring portion, and a fixing portion, which are continuously connected in this order. The contact portion includes a pair of contact pieces, which are opposed to each other in an opposing direction and are elastically displaceable respectively in the opposing direction. The fixing portion is fixed to the receptacle insulator. The spring portion renders the contact portion displaceable in a direction parallel to the opposing direction with respect to the fixing portion. The pair of contact pieces and the spring portion are protruded to a same side in the mating direction with respect to the coupling portion and are positioned to be mutually shifted in the socket alignment direction. A groove having both wall surfaces which are opposed to each other is formed on the receptacle insulator, the groove extending in the socket alignment direction, and each of the pair of contact pieces is positioned on each of the both wall surfaces. 
     According to the present invention, a connector includes the plug and the receptacle which are described above. The spring portion is positioned on a position on which the spring portion does not interfere with the pin contact in mating of the plug and the receptacle. 
     The plug according to the present invention is configured such that the protrusion formed in the insulator is positioned between the contact tabs of the pin contacts which are next to each other among the plurality of pin contacts, which are aligned, and thus there is no gap between the adjacent contact tabs. Accordingly, a part of the socket contact and a corner portion of the receptacle insulator, for example, of the receptacle are not fitted between the contact tabs in a mating operation with respect to the receptacle. As a result, favorable mating operability can be obtained and deformation and damages of the pin contacts and the socket contacts can be prevented. 
     The receptacle according to the present invention is mated with the plug to constitute a connector, and the spring portion renders the contact portion of the socket contact displaceable in the direction parallel to the opposing direction of the pair of contact pieces. Accordingly, even if positional accuracy, in the direction in which contact force is applied (the inter-row direction), of the pin contact of the plug is poor, for example, the contact portion of the socket contact can absorb displacement. Thus, stable contact force between the pin contact and the socket contact can be obtained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a conventional example of a plug. 
         FIG. 2A  is a perspective view illustrating an embodiment of a plug according to the present invention viewed from the upper side. 
         FIG. 2B  is a perspective view illustrating the plug of  FIG. 2A  viewed from the lower side. 
         FIG. 3A  is a plan view illustrating the plug of  FIG. 2A . 
         FIG. 3B  is a front elevational view illustrating the plug of  FIG. 3A . 
         FIG. 3C  is a sectional view taken along the  3 C- 3 C line of  FIG. 3B . 
         FIG. 3D  is a sectional view taken along the  3 D- 3 D line of  FIG. 3A . 
         FIG. 4A  is a perspective view illustrating an insulator of  FIG. 2A  viewed from the upper side. 
         FIG. 4B  is a perspective view illustrating the insulator of  FIG. 4A  viewed from the lower side. 
         FIG. 5A  is a plan view illustrating the insulator of  FIG. 4A . 
         FIG. 5B  is a bottom view illustrating the insulator of  FIG. 5A . 
         FIG. 5C  is a sectional view taken along the  5 C- 5 C line of  FIG. 5A . 
         FIG. 6A  is a perspective view illustrating a pin contact of  FIG. 2A . 
         FIG. 6B  is a perspective view illustrating the pin contact of  FIG. 6A  viewed from the opposite side. 
         FIG. 7A  is a perspective view illustrating another shape example of the pin contact. 
         FIG. 7B  is a perspective view illustrating the pin contact of  FIG. 7A  viewed from the opposite side. 
         FIG. 8A  is a plan view illustrating a metal fitting of  FIG. 2A . 
         FIG. 8B  is a front elevational view illustrating the metal fitting of  FIG. 8A . 
         FIG. 8C  is a perspective view illustrating the metal fitting of  FIG. 8A  viewed from the rear side. 
         FIG. 8D  is a perspective view illustrating the metal fitting of  FIG. 8A  viewed from the front side. 
         FIG. 9A  is a perspective view illustrating an embodiment of a receptacle according to the present invention viewed from the upper side. 
         FIG. 9B  is a perspective view illustrating the receptacle of  FIG. 9A  viewed from the lower side. 
         FIG. 10A  is a front elevational view illustrating the receptacle of  FIG. 9A . 
         FIG. 10B  is a bottom view illustrating the receptacle of  FIG. 1.0A . 
         FIG. 10C  is a sectional view taken along the  10 C- 10 C line of  FIG. 10B . 
         FIG. 11A  is a perspective view illustrating a receptacle insulator of  FIG. 9A  viewed from the upper side. 
         FIG. 11B  is a perspective view illustrating the receptacle insulator of  FIG. 11A  viewed from the lower side. 
         FIG. 12A  is a plan view illustrating the receptacle insulator of  FIG. 11A . 
         FIG. 12B  is a bottom view illustrating the receptacle insulator of  FIG. 12A . 
         FIG. 12C  is a sectional view taken along the  12 C- 12 C line of  FIG. 12B . 
         FIG. 13A  is a front elevational view illustrating a socket contact of  FIG. 9A . 
         FIG. 13B  is a perspective view illustrating the socket contact of  FIG. 13A . 
         FIG. 13C  is a perspective view illustrating the socket contact of  FIG. 13B  viewed from the opposite side. 
         FIG. 14A  is a plan view illustrating the metal fitting of  FIG. 9A . 
         FIG. 14B  is a front elevational view illustrating the metal fitting of  FIG. 14A . 
         FIG. 14C  is a perspective view illustrating the metal fitting of  FIG. 14A  viewed from the rear side. 
         FIG. 14D  is a perspective view illustrating the metal fitting of  FIG. 14A  viewed from the front side. 
         FIG. 15  is a perspective view illustrating a mating state of the plug of  FIG. 2A  and the receptacle of  FIG. 9A . 
         FIG. 16A  is a plan view illustrating the mating state of the plug of  FIG. 2A  and the receptacle of  FIG. 9A . 
         FIG. 16B  is a front elevational view illustrating the mating state of  FIG. 16A . 
         FIG. 17A  is an enlarged sectional view taken along the  17 A- 17 A line  6 A. 
         FIG. 17B  is an enlarged sectional view taken along the  17 B- 17 B line of  FIG. 16B . 
         FIG. 17C  is an enlarged sectional view taken along the  17 C- 17 C line of  FIG. 16B . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments according to the present invention are described below. 
       FIGS. 2A and 2B  and  FIGS. 3A to 3D  illustrate a plug in a board to board connector used for electrically connecting boards to each other, as an embodiment of a plug according to the present invention. This plug  100  includes an insulator  20  constituting a housing, 24 pin contacts  40  which are arranged and secured to the insulator  20 , and a pair of metal fittings  50  attached on a periphery of the insulator  20 , in this example. The configuration of each component is first described. 
     The insulator  20  is made of heat resistant resin such, as liquid crystal polymer. In this example, the insulator  20  has a bottom plate portion  21  having a rectangular shape and lateral walls are formed on a peripheral edge of the bottom plate portion  21 , as illustrated in  FIGS. 4A and 4B  and  FIGS. 5A to 5C . The lateral walls are a pair of lateral walls  22  positioned on long side portions of the bottom plate portion  21  and a pair of lateral walls  23  positioned on short side portions of the bottom plate portion  21 . 
     On the bottom plate portion  21 ,  24  through holes  24  are formed to be arranged in a lattice in which six through holes are aligned in the long side direction and four through holes are aligned in the short side direction. Hereinafter, the direction in which six through holes  24  are aligned is referred to as an alignment direction and the direction in which four through holes  24  are aligned is referred to as an inter-row direction. The through hole  24  is a rectangular hole elongated in the alignment direction and is formed to have a portion slightly wider (longer) in the alignment direction on the lower surface  21   b  side of the bottom plate portion  21  as illustrated in  FIG. 5C . 
     On the bottom plate portion  21 ,  24  through holes  25  are further formed to be arranged in a lattice in which six through holes are aligned in the alignment direction and four through holes are aligned in the inter-row direction as is the case with the through holes  24 . The through holes  25  are paired with the through holes  24  respectively and the through hole  25  is formed on a position, which is shifted from the through hole  24  in the inter-row direction, on one end side in the alignment direction of the through hole  24 . The through hole  25  is a rectangular hole and a concave portion  26  that communicates the through hole  24  and the through hole  25  is formed between the through hole  24  and the through hole  25 , which are paired, on the lower surface  21   b  of the bottom plate portion  21 . 
     A protrusion  27  is formed between each two through holes  24 , which are adjacent to each other in the alignment direction, in a state that the protrusion  27  stands up to the orthogonally-upper side from the upper surface  21   a , which is an inner bottom surface of the insulator  20 , of the bottom plate portion  21 . Further, protrusions  28  are also respectively formed on the outer sides in the alignment direction of the through holes  24 , which are positioned on both ends in the alignment direction, in a state that the protrusions  28  stand up to the upper side from the upper surface  21   a  of the bottom plate portion  21 . Hereinafter, the standing direction (the orthogonally-upper direction) of the protrusion  27  with respect to the upper surface  21   a  of the bottom plate portion  21  is referred to as a mating direction. 
     The protrusion  27  is formed to stand up from the whole region, which is between the adjacent through holes  24 , of the upper surface  21   a  of the bottom plate portion  21 . On lateral surfaces, on both sides facing the alignment direction, of the protrusion  27 , two projecting strips  27   a  are formed to be extended in the mating direction. The projecting strips  27   a  are each projected to the through hole  24 . These two projecting strips  27   a  are positioned on both ends in the inter-row direction on the lateral surfaces of the protrusion  27  and these projecting strips  27   a  form a groove  27   b , which extends in the mating direction and has a trapezoidal section, on each of the lateral surfaces of both sides of the protrusion  27 . 
     Further, two projecting strips  28   a  are formed also on lateral surface on a side, which faces the alignment direction and on which the through hole  24  is positioned, of the protrusion  28  so that the projecting strips  28   a  is projected to the through hole  24 , as is the case with the protrusion  27 . These projecting strips  28   a  form a groove  28   b  which extends in the mating direction and has a trapezoidal section. Here, the protrusion  28  is formed to be slightly lower than the protrusion  27  and the lateral surface on a side, which faces the alignment direction and on which the through hole  24  is not formed, is formed to be an inclined surface. 
     On both sides in the inter-row direction of the protrusions  27  and  28  which are aligned and positioned in the alignment direction, reinforcement portions  29  are formed on the upper surface  21   a  of the bottom plate portion  21 . The reinforcement portions  29  are coupled with base end portions of the protrusions  27  and  28  while sandwiching the base end portions and have a rib-like shape. Accordingly, the protrusions  27  and  28  stand up from the upper surface  21   a  of the bottom plate portion  21  are reinforced by the reinforcement portions  29 . Though the reinforcement portion  29  is formed from the protrusion  28  positioned on one end side in the alignment direction to the protrusion  28  positioned on the other end side, the reinforcement portion  29  is partially cut out on a part on which each through hole  24  is positioned. In this example, the reinforcement portion  29  is cut out on one half portion (right half portion), in the alignment direction, of the through hole  24  as illustrated in  FIG. 5A . 
     A convex portion  31  is formed on each center portion, in the alignment direction, of a pair of lateral walls  22  positioned on the long side portions of the bottom plate portion  21 . The convex portion  31  protrudes to the outer surface side and protrudes in the mating direction. Further, a pair of convex portions  32  is each formed on both portions interposing the convex portion  31  in the alignment direction, on the pair of lateral walls  22  so that the convex portions  32  protrude to the outer surface side. 
     On the other hand, convex portions  33  protruding to the outer surface side are respectively formed on both end portions, in the inter-row direction, of a pair of lateral walls  23  positioned on the short side portions of the bottom plate portion  21 . 
     The pin contact  40  is formed to have a shape illustrated in  FIGS. 6A and 6B . The pin contact  40  is composed of a fixing portion  41  having a fork shape, a contact tab  42  standing up from the fixing portion  41 , and a bent portion  43  which is formed by bending one leg portion of the fixing portion  41  and bending back the end of the leg portion to the standing direction (mating direction) of the contact tab  42 . 
     The contact tab  42  is formed to have a plate shape and a pair of planar surfaces of the contact tab  42  on two mutually opposite sides thereof which are parallel to each other form contact surfaces  42   a  which are brought into contact with a mating socket contact. The lateral surfaces on both sides in the width direction of the contact tab  42  and the end surface (upper surface) of the contact tab  42  are chamfered and accordingly, projecting strips  42   b  having a trapezoidal section are respectively formed on the lateral surfaces of the contact tab  42  to be extended in the mating direction. Here, an intermediate portion of the bent portion  43  is a connection portion  43   a  which is to be connected with an electrode pad of a board on which the plug  100  is to be mounted. 
     The pin contact  40  is made of Cu alloy, for example, and Au plating is applied on the surface thereof. 
     The metal fitting  50  is formed to have a shape illustrated in  FIGS. 8A to 8D , that is, the metal fitting  50  has a U shape as a whole, Each of both leg portions  51  of the U shape is composed of an upper plate portion  51   a  which is to be put on the upper surface of the lateral wall  22  of the insulator  20  and lateral plate portion  51   b  which is to be positioned along the outer surface side of the lateral wall  22 . On a lower end of a center portion, in the longitudinal direction, of the lateral plate portion  51   b , a fixing piece  52  is formed so that the fixing piece  52  is bent and extended outward from the lateral plate portion  51   b . Here, cutouts  53  are formed on both sides of a part, on which the fixing piece  52  is positioned, of the lateral plate portion  51   b , and a protrusion  54  protruding to the cutout  53  is formed on a part, which is close to the end of the leg portion  51 , of the lateral plate portion  51   b.    
     Further, an intermediate portion  55  of the U shape of the metal fitting  50  is composed of an upper plate portion  55   a  which is to be put on the upper surface of the lateral wall  23  of the insulator  20  and a lateral plate portion  55   b  which is to be positioned along the outer surface side of the lateral wall  23 . The lateral plate portion  55   b  is separated from adjacent lateral plate portions  51   h . Protrusions  56 , which mutually protrude outward, are formed respectively on both end surfaces in the longitudinal direction of the lateral plate portion  55   b  and a fixing piece  57  is formed on a lower end of a center portion, in the longitudinal direction, of the lateral plate portion  55   b  so that the fixing piece  57  is bent and extended outward from the lateral plate portion  55   b.    
     Assembly of the plug  100  illustrated in  FIGS. 2A and 2B  and  FIGS. 3A to 31 ) is now described. 
     The pin contact  40  is attached to the insulator  20  such that the contact tab  42  is inserted from the lower surface  21   b  of the bottom plate portion  21  into the through hole  24  on the bottom plate portion  21  of the insulator  20  and then the fixing portion  41  is press-fitted, as illustrated in  FIG. 3D . In this case, the bent portion  43  of the pin contact  40  is housed in the concave portion  26  on the lower surface  21   b  of the bottom plate portion  21  and the end of the bent portion  43  is fitted into the through hole  25  of the bottom plate portion  21 . The connection portion  43   a , which is an intermediate portion, of the bent portion  43  is exposed on the lower surface.  21   b  of the bottom plate portion  21 . 
     The contact tab  42  of the pin contact  40  is protruded from the upper surface  21   a  of the bottom plate portion  21  and stand up in the mating direction. Each of the protrusions  27  is positioned between two of the contact tabs  42  which are next to each other in the alignment direction. The projecting strip  42   b , which is formed on the lateral surface faced the alignment direction and opposed to the lateral surface of the protrusion  27  in the alignment direction, of the contact tab  42  is fitted into the groove  27   b  of the protrusion  27 . Here, the projecting strips  42   b , which are positioned on the outer sides in the alignment direction, of the contact tabs  42  positioned on both ends in the alignment direction are fitted into the grooves  28   b  of the protrusions  28 . 
     Thus attached, the pin contacts  40  are aligned so that the contact surfaces  42   a  are parallel to the alignment direction. Since the protrusion  27  is each positioned between the contact tabs  42  which are next to each other in the alignment direction, a gap between the contact tabs  42  which are next to each other in the alignment direction is closed by the protrusion  27 . In this example, the thickness, in the inter-row direction, of the protrusions  27  and  28  is set to be equal to the thickness of the contact tab  42 , so that each pair of planar surfaces of the protrusions  27  and  28  on two mutually opposite sides thereof which are parallel to each other are respectively flush with the contact surfaces  42   a  on both sides of the contact tab  42  adjacent to the protrusions  27  and  28 . 
     The pair of metal fittings  50  is fitted to the lateral walls  22  and  23  of the insulator  20  from the upper side to be attached to the insulator  20  as illustrated in  FIGS. 2A and 2B . The pair of protrusions  56  formed on the lateral plate portion  55   b  is engaged with the convex portions  33 , which are formed on the lateral wall  23 , and locked, and the protrusions  54  formed on the lateral plate portions  51   b  are engaged with the convex portions  32 , which are formed on the lateral walls  22 , and locked. Thus, the metal fittings  50  are solidly fixed on the insulator  20 . The fixing pieces  52  and  57  of the metal fitting  50  are positioned on the lower surface  21   b  side of the bottom plate portion  21  of the insulator  20 . 
     In the plug  100  configured as described above, the protrusion  27  of the insulator  20  is positioned between the contact tabs  42  of the pin contacts  40  which are next to each other in the alignment direction and thus there is no gap between the contact tabs  42 . Accordingly, a part of a socket contact and a corner portion of a receptacle insulator, for example, of a receptacle are not fitted between the contact tabs  42  in a mating operation with respect to the receptacle. As a result, deformation and damages of the pin contacts  40  and socket contacts can be prevented and favorable mating operability can be obtained. 
     This example employs the configuration that the projecting strips  42   b  are formed on the lateral surfaces, which face the alignment direction, of the contact tabs  42  of the pin contacts  40  and the projecting strips  42   b  are fitted into the grooves  27   b  and  28   b  of the protrusions  27  and  28  of the insulator  20 , so that the standing state of the contact tabs  42  is solidly maintained by the insulator  20 . The projecting strip  42   b  has the trapezoidal section in this example, but the projecting strip  42   b  may have a triangular section or a convex section. On the protrusions  27  and  28  of the insulator  20 , grooves corresponding to the shape of the projecting strip  42   b  of the contact tab  42  are formed. 
     On the other hand, the configuration that a projecting strip is not formed on a contact tab of a pin contact may be employed so as to simplify shapes of a pin contact and an insulator.  FIGS. 7A and 7B  illustrate a shape of a pin contact  40 ′ having a contact tab  42 ′ in which a projecting strip is not formed on lateral surfaces facing the alignment direction. 
     Though the pin contacts  40  are press-fitted and arranged in the insulator  20  in the above-described example, the pin contacts can be arranged in the insulator by insert molding, for example, instead of press-fitting. 
     The configuration of a receptacle according to the present invention that mate with the plug  100  described above is now described. 
       FIGS. 9A and 9B  and  FIGS. 10A to 10C  illustrate a receptacle according to an embodiment of the present invention. This receptacle  200  is composed of a receptacle insulator  60  constituting a housing, 24 socket contacts  80  which are housed in the receptacle insulator  60  and are arranged and held in a lattice, and a pair of metal fittings  90  attached on a periphery of the receptacle insulator  60 , in this example. Hereinafter, in 24 socket contacts  80  arranged in a lattice, the direction in which six socket contacts  80  are aligned is referred to as a socket alignment direction and the direction in which four socket contacts  80  are aligned is referred to as a socket inter-row direction. The configuration of each component is first described. 
     The receptacle insulator  60  is made of heat resistant resin such as liquid crystal polymer as is the case with the insulator  20 . In this example, the insulator  60  has a bottom plate portion  61  having a shape obtained by cutting out corner portions of a rectangle and lateral walls are formed on a peripheral edge of the bottom plate portion  61 , as illustrated in  FIGS. 11A and 11B  and  FIGS. 12A to 12C , The lateral walls are a pair of lateral walls  62  positioned on long side portions of the bottom plate portion  61  and a pair of lateral walls  63  positioned on short side portions of the bottom plate portion  61 . 
     The bottom plate portion  61  has a pedestal shaped portion  64  which protrudes to the mating direction with respect to the plug  100  and four grooves  65  which extend in the socket alignment direction of the socket contacts  80  are formed on an upper surface  64   a  of the pedestal shaped portion  64 . Further on the pedestal shaped portion  64 ,  24  through holes  66  are formed to be arranged in a lattice, in which six through holes  66  are aligned in the socket alignment direction and four through holes  66  are aligned in the socket inter-row direction, from the upper surface  64   a  of the pedestal shaped portion  64  to a lower surface  61   a  of the bottom plate portion  61 . Each of the six through holes  66  aligned in the socket alignment direction is positioned across the groove  65 . Accordingly, six pairs of concave portions  67 , which are opposed to each other, are formed on mutually-opposed wall surfaces (inner wall surfaces) along the extending direction (socket alignment direction) of the groove  65 . 
     On the lower surface  61   a  of the bottom plate portion  61 , concave portions  68 , which communicate with the through holes  66  in the socket alignment direction, are formed to be paired with respective through holes  66 . 
     On each center portion of a pair of lateral walls  62 , which are positioned on the long side portions of the bottom plate portion  61 , a convex portion  69 , which protrudes to the inner surface side and the outer surface side and also protrudes in the mating direction, is formed. Further, convex portions  71  which protrude to the inner surface side and to the mating direction are formed on portions, interposing the convex portion  69  in the socket alignment direction, of the lateral wall  62 . 
     On the other hand, on each center portion of a pair of lateral walls  63 , which are positioned on the short side portions of the bottom plate portion  61 , a convex portion  72 , which protrudes to the inner surface side and to the mating direction, is formed. Further, corner frames  73  are formed to protrude outward on outer surfaces of four corner portions which are formed by the lateral walls  62  and the lateral walls  63 . 
     The socket contact  80  is formed to have a shape illustrated in  FIGS. 13A to 13C . The socket contact  80  includes a contact portion  81 , a fixing portion  82 , a connection portion  83 , a spring portion  84 , and a coupling portion  85 . The contact portion  81  includes a pair of contact pieces  81   a  which are opposed to each other and can be elastically displaced respectively to the opposing direction. 
     The pair of contact pieces  81   a  comes into contact with the contact tab  42  of the pin contact  40  at two points while sandwiching the contact tab  42 . Ends of the contact pieces  81   a  are bent outward mutually. The fixing portion  82  is a portion which is fixed and held on the bottom plate portion  61  of the receptacle insulator  60 . The connection portion  83  which is connected with an electrode pad of a board on which the receptacle  200  is to be mounted is formed such that a center portion on the lower end side of the fixing portion  82  is cut and raised and thus connected with the fixing portion  82 . 
     The spring portion  84  has the U shape and one end thereof is connected with the fixing portion  82 . The coupling portion  85  connects the other end of the spring portion  84  and the contact portion  81 , and the spring portion  84  has a function to render the contact portion  81  displaceable in the direction parallel to the opposing direction of the pair of contact pieces  81   a , with respect to the fixing portion  82 . 
     The spring portion  84  and the pair of contact pieces  81   a  are configured to protrude to the same side in the mating direction with the plug  100 , with respect to the coupling portion  85 , and are positioned to be shifted from each other in the socket alignment direction of the socket contacts  80 . Further, the spring portion  84  and the pair of contact pieces  81   a  are positioned to be shifted from each other in the direction parallel to the opposing direction of the pair of contact pieces  81   a  as well. 
     The socket contact  80  is made of Cu alloy, for example, and Au plating is applied on the surface thereof, as is the case with the pin contact  40 . 
     The metal fitting  90  is formed to have a shape illustrated in  FIGS. 14A to 14D , that is, the metal fitting  90  has a U shape as a whole. Each of both leg portions of the U shape is composed of a lateral plate  91  which is to be positioned along the outer surface side of the lateral wall  62  of the receptacle insulator  60 , On two portions excluding the center portion in the longitudinal direction of the lateral plate  91 , bent pieces  92  and  93  are formed in an inwardly-bent shape. On the bent piece  92  positioned closer to the end of the lateral plate  91  in the longitudinal direction, a protruding portion  92   a  is formed to protrude inward, Here, an extension piece  94  is formed on the lower end of the lateral plate  91  and a protrusion  95  is formed on the end surface of the extension piece  94 . 
     The intermediate portion of the U shape of the metal fitting  90  is composed of a lateral plate  96  which is to be positioned along the outer surface side of the lateral wall  63  of the receptacle insulator  60 . On the lower end in the center portion in the longitudinal direction of the lateral plate  96 , a fixing piece  97  is formed so that the fixing piece  97  is bent and extended outward from the lateral plate  96 . Further, bent pieces  98  and  99  are formed in an inwardly-bent manner on both sides of the portion, on which the fixing piece  97  is formed, in the longitudinal direction of the lateral plate  96 . 
     Assembly of the receptacle  200  illustrated in  FIGS. 9A and 9B  and  FIGS. 10A to 10C  is now described. 
     The socket contact  80  is attached to the receptacle insulator  60  such that the contact portion  81  is inserted from the lower surface  61   a  of the bottom plate portion  61  into the through hole  66  on the bottom plate portion  61  of the receptacle insulator  60  and then the fixing portion  82  is press-fitted to the concave portion  68  formed on the lower surface  61   a  of the bottom plate portion  61 , as illustrated in  FIG. 10B . The pair of contact pieces  81   a  of the contact portion  81  is positioned on the concave portions  67 , which are formed on the wall surfaces of the groove  65  to be opposed to each other, as illustrated in  FIG. 9A . 
     The spring portion  84  of the socket contact  80  is housed in the concave portion  68  and the connection portion  83  and the coupling portion  85  are exposed on the lower surface  61   a  of the bottom plate portion  61 . 
     The pair of metal fittings  90  is fitted to the lateral walls  62  and  63  of the receptacle insulator  60  from the upper side to be attached to the insulator  60  as illustrated in  FIGS. 9A and 9B . The protrusion  95  formed on the extension piece  94  of the lateral plate  91  is engaged with the corner frame  73 , which is formed on a corner portion formed by the lateral walls  62  and  63 , to be locked. Each of the bent pieces  92  and  93  pinches the lateral wall  62  and each of the bent pieces  98  and  99  pinches the lateral wall  63 . The metal fittings  90  are thus attached to the receptacle insulator  60  and the fixing piece  97  of the metal fitting  90  is positioned on the lower surface  61   a  side of the bottom plate portion  61  of the receptacle insulator  60 . 
     In the receptacle  200  configured as described above, four grooves  65  extending in the socket alignment direction are formed on the receptacle insulator  60  and the contact portions  81  of six socket contacts  80  are aligned in each of the grooves  65 . 
     The socket contact  80  includes the spring portion  84  which renders the contact portion  81  displaceable in the direction parallel to the opposing direction of the pair of contact pieces  81   a , as described above. Accordingly, even if positional accuracy, in the inter-row direction, of the contact tab  42  of the mating pin contact  40  which is inserted between the pair of contact pieces  81   a , that is, positional accuracy in the direction in which contact force is applied is poor, the socket contact  80  can absorb displacement of the pin contact  40 , preventing the contact force from varying. Thus, desired stable contact force can be obtained. 
     The spring portion  84  is formed to protrude to the same side as the pair of contact pieces  81   a  with respect to the coupling portion  85 , and is positioned on a shifted position with respect to the pair of contact pieces  81   a  in the socket alignment direction. Through these points, even though the spring portion  84  is provided, the dimension of the receptacle  200  in the thickness of the mating direction and socket inter-row directions is not increased. 
     Further, the spring portion  84  is positioned on a shifted position with respect to the pair of contact pieces  81   a  in the direction parallel to the opposing direction, that is, the socket inter-row direction, of the pair of contact pieces  81   a  as well. Accordingly, the spring portion  84  is positioned on a position retreated from the groove  65  in the socket inter-row direction without providing a portion, to which the spring portion  84  protrudes, in the groove  65 , as illustrated in  FIG. 9A  and  FIG. 17B . 
     The plug  100  and the receptacle  200  described above constitute a board to board connector used for electrically connecting boards to each other. The plug  100  is mounted on a mounting surface of a board such that the connection portions  43   a  of the pin contacts  40  and the fixing pieces  52  and  57  of the metal fittings  50  are soldered on an electrode pad of the board. The receptacle  200  is mounted on a mounting surface of a mating board such that the connection portions  83  of the socket contacts  80  and the fixing pieces  97  of the metal fittings  90  are soldered on an electrode pad of the mating board. The bottom plate portion  21  of the insulator  20  of the plug  100  and the bottom plate portion  61  of the receptacle insulator  60  of the receptacle  200  are respectively mounted on the mounting surfaces of the boards. 
     The plug  100  and the receptacle  200  are mated and connected with each other in the orthogonal direction to the mounting surface.  FIG. 15  and  FIGS. 16A and 16B  illustrate a state that the plug  100  and the receptacle  200  are mated with each other while omitting illustration of the boards, and  FIGS. 17A to 17C  illustrate the sectional configuration of the state. 
     The row of the contact tabs  42  and the protrusions  27  and  28  which are aligned in the alignment direction in the plug  100  is inserted into the groove  65  of the receptacle  200 , the contact tab  42  is pinched by the pair of contact pieces  81   a  of the socket contact  80  as illustrated in  FIG. 17C , and the pin contact  40  and the socket contact  80  are thus connected with each other. 
     The lateral walls  22  and  23  of the plug  100 , to which the metal fittings  50  are attached, are fitted and housed in a concave portion formed between the lateral walls  62  and  63 , to which the metal fittings  90  of the receptacle  200  are attached, and the pedestal shaped portion  64 . The metal fitting  50  of the plug  100  and the metal fitting  90  of the receptacle  200  are mutually brought into contact with desired contact force and thus conducted with each other on the protruding portions  92   a  formed on the metal fitting  90 . 
     Since the spring portion  84  of the socket contact  80  is positioned on a position shunted from the groove  65  in the socket inter-row direction, the spring portion  84  is shifted from the contact tab  42  of the pin contact  40  in the socket inter-row direction and thus does not interfere with the contact tab  42  as illustrated in  FIG. 17B . 
     The plug and the receptacle which are mounted on mounting surfaces of boards and mated with each other in the orthogonal direction to the mounting surfaces are described above, but a plug and a receptacle according to the present invention are not limited to the plug and the receptacle described above. A plug and a receptacle which are mounted on mounting surfaces of boards and mated with each other in the direction parallel to the mounting surfaces may be employed or a plug and a receptacle which are attached to cable terminals, for example, may be employed. 
     The foregoing description of the embodiment of the invention has been presented for the purpose of illustration and description. It is not intended to be exhaustive and to limit the invention to the precise form disclosed. Modifications or variations are possible in light of the above teaching. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.