Patent Publication Number: US-9899782-B2

Title: Connector assembly and connector assembly mounted structure

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a connector assembly and a connector assembly mounted structure. The present invention more particularly relates to a connector assembly in which a second connector is fitted to a first connector mounted on a connector holding plate. 
     A connector assembly configured to mount a first connector on a surface of a circuit board, and to fit a second connector from a rear face of the circuit board to a fitting portion of the first connector that passes through a through-hole formed in the circuit board to project from the rear face of the circuit board has conventionally been used. 
     For example, JP 5258123 B discloses, as a connector assembly of this type, a connector assembly including a first connector  2  mounted on a circuit board  1  and a second connector  3  to be fitted to the first connector  2  along a fitting axis C, as illustrated in  FIG. 30  and  FIG. 31 . 
     The circuit board  1  has a first face  1 A and a second face  1 B that are oriented in opposite directions to each other. A through-hole  1 C is formed in the circuit board  1 . A part of the first connector  2  passes through the through-hole  1 C and projects on the side of the second face  1 B of the circuit board  1 . 
     A plurality of mounting lands  1 D are formed on the first face  1 A of the circuit board  1  on the periphery of the through-hole  1 C. A plurality of mounting portions  2 A corresponding to the mounting lands  1 D are formed in the first connector  2 . The mounting portions  2 A are soldered to their corresponding mounting lands  1 D, respectively, to mount the first connector  2  on the first face  1 A of the circuit board  1 . 
     As illustrated in  FIG. 32 , fitting portions  2 B, each of which extends along the fitting axis C and has a concave shape that is open in the fitting direction, are formed in the first connector  2 . Further, convex portions  3 A projecting along the fitting axis C are formed on the second connector  3 . When the second connector  3  is fitted to the first connector  2  along the fitting axis C from the side of the second face  1 B of the circuit board  1 , the convex portions  3 A of the second connector  3  are received in the fitting portions  2 B of the first connector. 
     However, when the second connector  3  is fitted to the first connector  2 , the second connector  3  is brought into abutment against the first connector  2  along the fitting axis C. Such a large force or impact as to push up the first connector  2  along the fitting axis C is thus more likely to be exerted on the first connector  2  from the second connector  3 . 
     In such a case, such a large load as to separate the mounting portions  2 A from the mounting lands  1 D along the fitting axis C may be added to portions where the mounting portions  2 A of the first connector  2  are soldered to the mounting lands  1 D of the circuit board  1 . The portions where the mounting portions  2 A are soldered to the mounting lands  1 D may be thus broken. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to solve the above-mentioned conventional problems and an object of the present invention is to provide a connector assembly and a connector assembly mounted structure capable of preventing soldered portions from being broken during fitting. 
     A connector assembly according to the present invention comprises: a first connector to be mounted on a first face of a connector holding plate having the first face and a second face which are oriented in opposite directions to each other; and a second connector to be fitted to the first connector along a fitting direction from a side of the second face of the connector holding plate, wherein the first connector has a first contact and a mounting portion, and has a projecting portion which passes through a through-hole of the connector holding plate to project on the side of the second face of the connector holding plate along the fitting direction when the first connector is mounted on the first face of the connector holding plate through the mounting portion, and which includes at least a part of the first contact, wherein the second connector has a second contact and a second contact holding portion configured to hold the second contact, and the second contact holding portion has a first connector receiving portion extending along the fitting direction and an abutment portion formed at an end of the second contact holding portion on a side of the first connector and configured to be abutted against the second face of the connector holding plate, and wherein, when the second connector is fitted to the first connector from the side of the second face of the connector holding plate, at least a part of the projecting portion is received in the first connector receiving portion to bring the first contact and the second contact into contact with each other, and the abutment portion of the second contact holding portion can be abutted against the second face of the connector holding plate. 
     A connector assembly mounted structure according to the present invention comprises: a connector holding plate having a first face and a second face oriented in opposite directions to each other and having a through-hole formed therein; a first connector having a first contact and a mounting portion, and mounted on the first face of the connector holding plate through the mounting portion; and a second connector having a second contact and a second contact holding portion configured to hold the second contact, the second connector being to be fitted to the first connector along a fitting direction from a side of the second face of the connector holding plate, wherein the first connector has a projecting portion which passes through the through-hole of the connector holding plate to project on the side of the second face of the connector holding plate along the fitting direction and which includes at least a part of the first contact, wherein the second contact holding portion of the second connector has a first connector receiving portion extending along the fitting direction and an abutment portion formed at an end of the second contact holding portion on a side of the first connector and configured to be abutted against the second face of the connector holding plate, and wherein, when the second connector is fitted to the first connector from the side of the second face of the connector holding plate, at least a part of the projecting portion is received in the first connector receiving portion to bring the first contact and the second contact into contact with each other, and the abutment portion of the second contact holding portion can be abutted against the second face of the connector holding plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view for illustrating a connector assembly according to a first embodiment of the invention. 
         FIG. 2  is a perspective cross-sectional view of the connector assembly according to the first embodiment. 
         FIG. 3  is a perspective view for illustrating a first connector before being fixed to a circuit board and the circuit board. 
         FIG. 4  is a perspective view for illustrating a first housing and conductive members before being held in the first housing. 
         FIG. 5  is a perspective view of the first housing when viewed from below. 
         FIG. 6  is a perspective view for illustrating the first connector mounted on the circuit board. 
         FIG. 7  is a perspective view for illustrating a second housing and second contacts before being held in the second housing. 
         FIG. 8A  is a perspective view of the second housing when viewed from a lever side and  FIG. 8B  is a perspective view of the second housing when viewed from a lance side. 
         FIG. 9A  is a perspective view of the second contact when viewed from a first projection side and  FIG. 9B  is a perspective view of the second contact when viewed from a second projection side. 
         FIG. 10  is a perspective view of a second connector when viewed from behind. 
         FIG. 11  is a perspective cross-sectional view for illustrating the second connector. 
         FIG. 12  is a perspective view for illustrating the connector assembly of the first embodiment after fitting and a first face of the circuit board. 
         FIG. 13  is a perspective view for illustrating the connector assembly of the first embodiment after fitting and a second face of the circuit board. 
         FIG. 14  is a lateral cross-sectional view of the connector assembly of the first embodiment after fitting. 
         FIG. 15  is a perspective cross-sectional view of the connector assembly of the first embodiment after fitting. 
         FIG. 16  is a lateral cross-sectional view of a main part of the connector assembly of the first embodiment after fitting. 
         FIG. 17  is a lateral cross-sectional view for illustrating a retaining mechanism of the connector assembly according to the first embodiment. 
         FIG. 18  is a perspective view for illustrating a connector assembly according to a second embodiment of the invention. 
         FIG. 19  is a perspective cross-sectional view of the connector assembly according to the second embodiment. 
         FIG. 20  is a perspective view for illustrating a first connector of the connector assembly according to the second embodiment before being fixed to a circuit board and the circuit board. 
         FIG. 21  is a perspective view for illustrating a second connector of the connector assembly according to the second embodiment. 
         FIG. 22  is a perspective cross-sectional view for illustrating the second connector of the connector assembly according to the second embodiment. 
         FIG. 23  is a perspective view for illustrating the connector assembly of the second embodiment after fitting and a first face of the circuit board. 
         FIG. 24  is a perspective view for illustrating the connector assembly of the second embodiment after fitting and a second face of the circuit board. 
         FIG. 25  is a lateral cross-sectional view of the connector assembly of the second embodiment after fitting. 
         FIG. 26  is a perspective cross-sectional view of the connector assembly of the second embodiment after fitting. 
         FIG. 27  is a lateral cross-sectional view for illustrating a retaining mechanism of the connector assembly according to the second embodiment. 
         FIG. 28  is a lateral cross-sectional view for illustrating the circuit board mounted on a metallic chassis. 
         FIG. 29  is a lateral cross-sectional view for illustrating the circuit board mounted on another metallic chassis. 
         FIG. 30  is a perspective view for illustrating a conventional connector assembly in a fitted state and a first face of a circuit board. 
         FIG. 31  is a perspective view for illustrating the conventional connector assembly in the fitted state and a second face of the circuit board. 
         FIG. 32  is a perspective view for illustrating the conventional connector assembly before fitting. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention are described below with reference to the accompanying drawings. 
     First Embodiment 
     A configuration of a connector assembly according to a first embodiment is illustrated in  FIG. 1  and  FIG. 2 . The connector assembly according to the first embodiment includes a first connector  21  mounted on a circuit board  11 , and a second connector  31  to be fitted to the first connector  21  along a fitting axis C. 
     The circuit board  11  makes up a connector holding plate for holding the first connector  21 , and has a first face  11 A and a second face  11 B which are oriented in opposite directions to each other. The first connector  21  is mounted on the first face  11 A of the circuit board  11 . Further, a through-hole  12  is formed in the circuit board  11 . 
     The first connector  21  has a first housing  22  made of insulating resin, and two metallic conductive members  23  are held side by side in the first housing  22 . For the sake of convenience, a direction in which the two conductive members  23  are disposed is called X direction, a direction away from the second connector  31  toward the first connector  21  along the fitting axis C is called +Z direction, and a direction orthogonal to the X direction and the Z direction is called Y direction. 
     A part of the first connector  21  passes through the through-hole  12  of the circuit board  11  and projects on the side of the second face  11 B of the circuit board  11  to form a projecting portion  24 . 
     On the other hand, two cables  41  are connected to an end of the second connector  31  in the −Z direction, respectively. 
     As illustrated in  FIG. 3 , four mounting pads  13  are formed in advance on the periphery of the through-hole  12  on the first face  11 A of the circuit board  11 . These mounting pads  13  are connected to a wiring pattern (not shown) of the circuit board  11 . 
     The first housing  22  and the two conductive members  23  are illustrated in  FIG. 4 . The first housing  22  substantially has the shape of a rectangular parallelepiped. The first housing  22  has two conductive member insertion portions  22 A formed so as to be disposed side by side in the X direction. Each of these conductive member insertion portions  22 A extends to the inside of the first housing  22  so as to be located along an YZ plane. Each of the conductive member insertion portions  22 A has an opening in the Y direction. An upward-facing face  22 B oriented in the +Z direction is formed at an end of the first housing  22  in the −Z direction so as to be positioned between the two conductive member insertion portions  22 A that are disposed side by side in the X direction. 
     A lower end portion  22 C is formed at the end of the first housing  22  in the −Z direction so as to be located along an XY plane, as illustrated in  FIG. 5 . 
     As illustrated in  FIG. 4 , each conductive member  23  has a flat shape extending along the YZ plane and includes a pair of first contacts  23 A extending in the Z direction. The first contacts  23 A in the pair are disposed side by side in the Y direction and are connected to each other at their ends in the +Z direction. The first contacts  23 A in the pair have contact portions  23 B formed at their ends in the −Z direction, respectively, the contact portions  23 B projecting in the Y direction so as to face each other. Further, the first contacts  23 A in the pair have elasticity and are configured to be elastically deformable on the YZ plane. 
     A housing holding portion  23 C extending in the Y direction is connected to the ends of the first contacts  23 A of the pair in the +Z direction. Mounting portions  23 D oriented in the −Z direction are formed at both ends of the housing holding portion  23 C in the Y direction, respectively. 
     The conductive members  23  are inserted into their corresponding conductive member insertion portions  22 A of the first housing  22  along the Y direction, respectively, and the housing holding portions  23 C of the conductive members  23  are pressed into their corresponding conductive member insertion portions  22 A, respectively, whereby the two conductive members  23  are held in the first housing  22 . 
     When the first connector  21  is inserted into the through-hole  12  of the circuit board  11 , as illustrated in  FIG. 6 , a part of the first connector  21  passes through the through-hole  12  and projects from the second face  11 B of the circuit board  11  in the −Z direction to form the projecting portion  24 . The projecting portion  24  is formed of a part of the first housing  22  and a part of the pair of first contacts  23 A in each of the conductive members  23 . 
     In this process, the mounting portions  23 D of the two conductive members  23  are positioned on surfaces of their corresponding mounting pads  13  of the circuit board  11  and are soldered to their corresponding mounting pads  13 , whereby the first connector  21  is mounted on the circuit board  11  and the conductive members  23  are electrically connected to the mounting pads  13 . 
     As illustrated in  FIG. 7 , the second connector  31  includes a second housing  32  made of insulating resin, and two second contacts  33  made of metal and connected to ends of the cables  41 , respectively. The second housing  32  makes up a second contact holding portion for holding the second contacts  33 . 
     As illustrated in  FIG. 8A  and  FIG. 8B , the second housing  32  includes a lateral wall portion  32 A that has a rectangular prism shape extending in the Z direction and is open in the +Z direction, and an abutment portion  32 B formed along the XY plane so as to surround the entire periphery of an opening portion of the lateral wall portion  32 A. 
     Further, two contact insertion portions  32 C that are disposed side by side in the X direction and extend in the Z direction are formed inside the second housing  32 . These contact insertion portions  32 C are open in the −Z direction. 
     The lateral wall portion  32 A includes a first lateral wall  32 D oriented in the −Y direction and a second lateral wall  32 E oriented in the +Y direction. A lever  32 F extending in the Z direction is formed on the first lateral wall  32 D. The lever  32 F is connected to the first lateral wall  32 D through a connecting portion  32 G positioned in the middle of the lever  32 F in the Z direction. The connecting portion  32 G has elasticity and is configured to be capable of oscillating the lever  32 F on the YZ plane, the connecting portion  32 G being set as the base point. 
     Further, a first opening  32 H that is open in the −Y direction is formed in the first lateral wall  32 D, and an extremity portion of the lever  32 F in the +Z direction faces the first opening  32 H. 
     Two second openings  32 J that are open in the +Y direction and are disposed side by side in the X direction are formed in the second lateral wall  32 E of the second housing  32 . Lances  32 K are formed to extend in the +Z direction from ends of the second openings  32 J in the −Z direction, respectively. Each lance  32 K has a cantilever shape and is configured to be elastically deformable on the YZ plane. 
     As illustrated in  FIG. 9A  and  FIG. 9B , each second contact  33  has a substantially cylindrical shape extending in the Z direction. A guide portion  33 A having a smoothly curved shape is formed at an extremity of the second contact  33  in the +Z direction. 
     The second contact  33  has a first connecting portion  33 B oriented in the −Y direction and a second connecting portion  33 C oriented in the +Y direction. The second contact  33  also has a first projection  33 D formed so as to project in the −Y direction at a position on the −Z direction side with respect to the first connecting portion  33 B, and a second projection  33 E formed so as to project in the +Y direction at a position on the −Z direction side with respect to the second connecting portion  33 C. 
     A cable holding portion  33 F that is open in the −Y direction is formed at an end of the second contact  33  in the −Z direction. 
     When the second contacts  33  are connected to ends of the two cables  41 , respectively, and the second contacts  33  are inserted in their corresponding contact insertion portions  32 C of the second housing  32  from the −Z direction side of the second housing  32 , the second projections  33 E of the second contacts  33  move in the +Z direction while subjecting the lances  32 K of the second housing  32  to elastic deformation in the +Y direction, and the second contacts  33  are held in the second housing  32  in a state in which the second projections  33 E of the second contacts  33  are positioned on the +Z direction side of the lances  32 K of the second housing  32 . 
     As illustrated in  FIG. 11 , a first connector receiving portion  32 M extending in the Z direction is formed inside the lateral wall portion  32 A of the second housing  32 . A bottom portion  32 N is formed at an end of the first connector receiving portion  32 M in the −Z direction so as to extend along the XY plane, and the first connecting portion  33 B and the second connecting portion  33 C of each second contact  33  project in the +Z direction from the bottom portion  32 N of the first connector receiving portion  32 M. 
     Next, the operation of the connector assembly according to the first embodiment is described. 
     When the second connector  31  is moved in the +Z direction along the fitting axis C from the second face  11 B side of the circuit board  11  relative to the first connector  21  mounted on the circuit board  11 , the second connector  31  is fitted to the first connector  21 , as illustrated in  FIG. 12  and  FIG. 13 . 
     When the second connector  31  is fitted to the first connector  21 , first of all, the projecting portion  24  of the first connector  21  starts to be received in the first connector receiving portion  32 M. Then, the guide portion  33 A of the second contact  33  comes into contact with the pair of contact portions  23 B of the conductive member  23 . The guide portion  33 A has a curved shape, and is hence inserted between the pair of contact portions  23 B with a small force. Further, the second contact  33  advances in the +Z direction while pushing the first contacts  23 A of the conductive member  23  outward, and the first connecting portion  33 B and the second connecting portion  33 C of the second contact  33  come into contact with the pair of contact portions  23 B of the conductive member  23 . 
     Thereafter, the second connector  31  further advances in the +Z direction, and as illustrated in  FIG. 14  and  FIG. 15 , at a point in time when the abutment portion  32 B of the second housing  32  in the second connector  31  is abutted against the second face  11 B of the circuit board  11 , the projecting portion  24  of the first connector  21  is received in the first connector receiving portion  32 M of the second connector  31  and fitting of the second connector  31  is completed. 
     When viewed from the fitting direction along the fitting axis C, the lateral wall portion  32 A of the second housing  32  has a portion that covers the projecting portion  24  of the first connector  21  over the entire circumferential area. 
     Each second contact  33  is sandwiched in the Y direction between the pair of first contacts  23 A of the conductive member  23  that have elasticity, and the pair of contact portions  23 B formed at the first contacts  23 A are in elastic contact with the first connecting portion  33 B and the second connecting portion  33 C of the second contact  33 , respectively. The second contact  33  is thus electrically connected to the conductive member  23 . At that time, the contact points between the second contact  33  and the conductive member  23  are positioned on the second face  11 B side of the circuit board  11 . 
     As illustrated in  FIG. 6 , the first connector  21  is mounted on a wiring pattern (not shown) of the circuit board  11  through the mounting pads  13  of the circuit board  11 . Further, as illustrated in  FIG. 7 , the second connector  31  is connected to the cables  41 . Therefore, fitting of the second connector  31  to the first connector  21  allows the cables  41  to be connected to the wiring pattern of the circuit board  11  through the first connector  21  and the second connector  31 . 
     When the second connector  31  is fitted to the first connector  21 , the abutment portion  32 B of the second housing  32  in the second connector  31  is abutted against the second face  11 B of the circuit board  11  over the entire circumferential area when viewed from the fitting direction along the fitting axis C. 
       FIG. 16  is a cross-sectional view of a main part of the connector assembly of the first embodiment after fitting, and is a partial enlarged view of  FIG. 14 . As illustrated in  FIG. 16 , when the second connector  31  is fitted to the first connector  21 , the bottom portion  32 N of the first connector receiving portion  32 M in the second connector  31  does not come into contact with the lower end portion  22 C of the projecting portion  24  in the first connector  21  but a clearance CL in the Z direction is formed between the bottom portion  32 N and the lower end portion  22 C. 
     The first connector  21  and the second connector  31  are configured in such a manner that a part of the projecting portion  24  of the first connector  21  that is oriented in the −Z direction does not come into contact with any part of the second connector  31  during the fitting. 
     Therefore, when the second connector  31  is fitted to the first connector  21 , such a large force as to push up the first connector  21  in the +Z direction is prevented from being exerted on the first connector  21  from the second connector  31 . As a result, a large force that causes the mounting portions  23 D as soldering portions of the first connector  21  to be separated from the mounting pads  13  of the circuit board  11  in the +Z direction is not exerted on the mounting portions  23 D, and the portions where the mounting portions  23 D are soldered to the mounting pads  13  are prevented from being broken, whereby a reliable connector assembly can be realized. 
     As illustrated in  FIG. 17 , a pawl  32 P projecting in the +Y direction so as to approach the fitting axis C is formed at an extremity in the +Z direction of the lever  32 F formed on the first lateral wall  32 D of the second housing  32 . The pawl  32 P is positioned at the first opening  32 H of the second housing  32 . 
     When fitting the second connector  31 , the pawl  32 P is pressed by the first housing  22  to cause elastic deformation of the connecting portion  32 G, thus oscillating the lever  32 F on the YZ plane to displace the pawl  32 P in the −Y direction. Then, when the pawl  32 P advances in the +Z direction to pass the upward-facing face  22 B of the first housing  22 , the pawl  32 P is no longer pressed by the first connector  21  and is displaced in the +Y direction to be positioned on the +Z direction side of the upward-facing face  22 B. Therefore, even when a force in the −Z direction is exerted on the second connector  31  for some reason, the pawl  32 P is caught on the upward-facing face  22 B to limit displacement of the second connector  31  in the −Z direction with respect to the first connector  21 . Therefore, after the second connector  31  is fitted to the first connector  21 , the second connector  31  is prevented from being separated from the first connector  21  in the −Z direction. 
     Further, in cases where the connector assembly is configured, for smooth fitting of the second connector  31  to the first connector  21 , to generate a slight gap in the Z direction between the pawl  32 P of the second connector  31  and the upward-facing face  22 B of the first connector  21  when the abutment portion  32 B of the second housing  32  in the second connector  31  is abutted against the second face  11 B of the circuit board  11 , the second connector  31  after the fitting may be slightly displaced in the −Z direction with respect to the first connector  21  to cause the abutment portion  32 B to slightly move away in the −Z direction from the second face  11 B of the circuit board  11 . However, when a force in the +Z direction is exerted on the second connector  31  in this state, the abutment portion  32 B would be abutted against the second face  11 B of the circuit board  11 . In other words, the abutment portion  32 B of the second connector  31  is about to be abutted against the second face  11 B of the circuit board  11 . Therefore, as described above, such a large force as to push up the first connector  21  in the +Z direction is prevented from being exerted on the first connector  21  from the second connector  31 , thus keeping the portions where the mounting portions  23 D are soldered to the mounting pads  13  from being broken. 
     After the second contacts  33  are pressed into the second housing  32  as illustrated in  FIG. 10 , the second projections  33 E of the second contacts  33  in the second connector  31  are positioned, as illustrated in  FIG. 16 , on the +Z direction side with respect to the lances  32 K of the second housing  32 , respectively. The second projections  33 E are thus caught on ends of the lances  32 K in the +Z direction, and hence the second contacts  33  are prevented from being separated from the second housing  32  in the −Z direction. 
     Further, a downward-facing face  32 Q that is oriented in the −Z direction is formed on the first lateral wall  32 D of the second housing  32 , and the first projections  33 D are opposed to the downward-facing face  32 Q. Therefore, when the second contacts  33  are inserted into the second housing  32 , the first projections  33 D are abutted against the downward-facing face  32 Q to determine the positions of the second contacts  33  in the Z direction with respect to the second housing  32 . 
     According to the above-mentioned first embodiment, the clearance CL in the Z direction is formed between the lower end portion  22 C of the projecting portion  24  in the first connector  21  and the bottom portion  32 N of the first connector receiving portion  32 M in the second connector  31  when the second connector  31  is fitted to the first connector  21 . However, the lower end portion  22 C may come into contact with the bottom portion  32 N as long as the abutment portion  32 B of the second housing  32  is abutted against the second face  11 B of the circuit board  11  to prevent such a large force as to push up the first connector  21  in the +Z direction from being exerted on the first connector  21 . With such a configuration, the portions where the mounting portions  23 D (soldering portions) are soldered to the mounting pads  13  can be also prevented from being broken. 
     Further, when the second connector  31  is fitted to the first connector  21 , the end in the +Z direction of the lateral wall portion  32 A of the second housing  32  covers the projecting portion  24  of the first connector  21  over the entire circumferential area when viewed from the fitting direction along the fitting axis C. However, the end in the +Z direction may partially cover the projecting portion  24  of the first connector  21 . The abutment portion  32 B of the second housing  32  would be thus abutted against the second face  11 B of the circuit board  11  partially in the circumferential direction when viewed from the fitting direction along the fitting axis C. Nevertheless, exertion of such a large force as to push up the first connector  21  in the +Z direction can be suppressed to prevent the portions where the mounting portions  23 D are soldered to the mounting pads  13  from being broken. 
     The first connector  21  has the two conductive members  23  and the second connector  31  has the two second contacts  33  so as to be adapted to the first connector  21 . However, this is not the sole case. More specifically, the first connector  21  may have one conductive member  23 , or three or more conductive members  23 . Further, the second connector  31  may have one second contact  33  or three or more second contacts  33  so as to be adapted to the first connector  21 . 
     Second Embodiment 
     According to the first embodiment, the first connector  21  includes the first housing  22  made of insulating resin and the conductive members  23  made of metal, and the second connector  31  includes the second housing  32  made of insulating resin and the second contacts  33  made of metal. However, this is not the sole case. According to a second embodiment, each of the first connector and the second connector includes a single metal member. 
     A connector assembly according to the second embodiment is illustrated in  FIG. 18 . The connector assembly according to the second embodiment includes a first connector  51  made of metal and mounted on a circuit board  71 , and a second connector  61  made of metal to be fitted to the first connector  51  along the fitting axis C. The circuit board  71  makes up a connector holding plate for holding the first connector  51 , and a through-hole  72  is formed in the circuit board  71 . 
     The circuit board  71  illustrated in  FIG. 18  is configured in the same manner as the circuit board  11  in the first embodiment except that the through-hole  72  is formed instead of the through-hole  12  illustrated in  FIG. 1 . 
     The first connector  51  is mounted on a first face  71 A of the circuit board  71 . Further, a cable  41  is connected to an end of the second connector  61  in the −Z direction. 
     As illustrated in  FIG. 19 , a part of the first connector  51  passes through the through-hole  72  of the circuit board  71  and projects in the −Z direction on the side of a second face  71 B of the circuit board  71  to form a projecting portion  52 . 
     As illustrated in  FIG. 20 , two mounting pads  13  are formed in advance on the first face  71 A of the circuit board  71  so as to sandwich the through-hole  72  in the Y direction. 
     The first connector  51  includes a first contact  53  extending in the Z direction, a top plate portion  54  connected to an end of the first contact  53  in the +Z direction and extending in the Y direction, and a pair of mounting portions  55  oriented in the −Z direction at both ends of the top plate portion  54  in the Y direction. 
     The first contact  53  has a pair of contact portions  53 A that extend in the Z direction and are oriented in the +X direction and the −X direction, respectively. The contact portions  53 A in the pair are connected to each other at their upper ends in the +Z direction. Further, each of the contact portions  53 A in the pair has a flat plate shape extending along the YZ plane. Ends in the −Z direction of the contact portions  53 A in the pair face each other in the X direction and are bent so as to be located along the XY plane, thereby forming an upward-facing face  53 C that is oriented in the +Z direction. Further, a cutout portion  53 D oriented in the +Y direction is formed at an end in the −Z direction of each contact portion  53 A in the pair. 
     When the first connector  51  is inserted into the through-hole  72  of the circuit board  71 , a part of the first contact  53  in the first connector  51  passes through the through-hole  72  and projects from the second face  71 B of the circuit board  71  in the −Z direction to form the projecting portion  52 . 
     In this process, the pair of mounting portions  55  in the first contact  53  are positioned on surfaces of their corresponding mounting pads  13  of the circuit board  71  and the mounting portions  55  are used as soldering portions to be soldered to their corresponding mounting pads  13 , thereby mounting the first connector  51  on the circuit board  71  while electrically connecting the first connector  51  to the mounting pads  13 . 
     As illustrated in  FIG. 21  and  FIG. 22 , the second connector  61  has a second contact holding portion  62 . The second contact holding portion  62  includes a lateral wall portion  63  that has a rectangular prism shape extending in the Z direction and is open in the +Z direction, and an abutment portion  64  that surrounds an opening portion of the lateral wall portion  63  and is formed to be located along the XY plane. A first connector receiving portion  65  extending in the Z direction is formed inside the lateral wall portion  63 . A cable holding portion  66  for holding an end of the cable  41  in the +Z direction is formed at an end of the first connector receiving portion  65  in the −Z direction. 
     The lateral wall portion  63  includes a pair of first lateral walls  63 A that face each other in the X direction. A pair of first openings  63 B that extend in the Z direction and are open in the X direction are formed in the pair of first lateral walls  63 A. A pair of second contacts  68  extending in the Z direction are connected to respective ends in the −Z direction of the first openings  63 B in the pair. 
     The second contacts  68  in the pair have arm portions  68 A that extend in the Z direction and form a pair. Contact portions  68 B in the pair that project so as to face each other in the X direction are formed at respective ends in the +Z direction of the arm portions  68 A in the pair. The arm portions  68 A in the pair have elasticity and are configured to be elastically deformable on an XZ plane. 
     The lateral wall portion  63  also includes a second lateral wall  63 C oriented in the −Y direction and a third lateral wall  63 D oriented in the +Y direction. A second opening  63 E that is open in the −Y direction is formed in the second lateral wall  63 C. An extension portion  63 F that is bent toward the inside of the first connector receiving portion  65  and extends in the −Z direction is formed at an end of the third lateral wall  63 D in the +Z direction. A projection  63 G projecting in the −Y direction is formed at an end of the extension portion  63 F in the −Z direction. The extension portion  63 F has elasticity and is configured to be elastically deformable on the YZ plane. 
     Each of the first connector  51  and the second connector  61  can be formed by subjecting a single metal sheet to cutting and bending. 
     Next, the operation of the connector assembly according to the second embodiment is described. 
     When the second connector  61  is moved in the +Z direction along the fitting axis C from the second face  71 B side of the circuit board  71  relative to the first connector  51  mounted on the circuit board  71 , the second connector  61  is fitted to the first connector  51 , as illustrated in  FIG. 23  and  FIG. 24 . 
     When the second connector  61  is fitted to the first connector  51 , first of all, the first connector receiving portion  65  of the second connector  61  starts to receive the projecting portion  52  of the first connector  51 . Then, the contact portions  68 B of the pair of second contacts  68  come into contact with an end of the first contact  53  in the −Z direction. Further, the arm portions  68 A in the pair of second contacts  68  advance in the +Z direction while being pushed outward by the first contact  53 , and the contact portions  68 B in the pair of second contacts  68  come into contact with the pair of contact portions  53 A in the first contact  53 . 
     Thereafter, the second connector  61  further advances in the +Z direction and, as illustrated in  FIG. 25  and  FIG. 26 , at a point in time when the abutment portion  64  of the second connector  61  is abutted against the second face  71 B of the circuit board  71 , the projecting portion  52  of the first connector  51  is received in the first connector receiving portion  65  of the second connector  61  and fitting of the second connector  61  is completed. 
     When viewed from the fitting direction along the fitting axis C, the lateral wall portion  63  of the second contact holding portion  62  has a portion that covers the projecting portion  52  of the first connector  51  over the entire circumferential area. 
     The first contact  53  is sandwiched in the X direction between the elastic arm portions  68 A of the pair of second contacts  68 , and the contact portions  68 B formed at the arm portions  68 A are in elastic contact with the pair of contact portions  53 A of the first contact  53 . The second contacts  68  are thus electrically connected to the first contact  53 . At that time, the contact points between the second contacts  68  and the first contact  53  are positioned on the second face  71 B side of the circuit board  71 . 
     When the second connector  61  is fitted to the first connector  51 , the abutment portion  64  of the second connector  61  is abutted against the second face  71 B of the circuit board  71  over the entire circumferential area when viewed from the fitting direction along the fitting axis C. Further, the first connector  51  and the second connector  61  are configured in such a manner that a part of the projecting portion  52  of the first connector  51  that is oriented in the −Z direction does not come into contact with any part of the second connector  61  during the fitting. 
     Therefore, when the second connector  61  is fitted to the first connector  51 , such a large force as to push up the first connector  51  in the +Z direction is prevented from being exerted on the first connector  51  from the second connector  61 . As a result, a large force that causes the mounting portions  55  as soldering portions of the first connector  51  to be separated from the mounting pads  13  of the circuit board  71  in the +Z direction is not exerted on the mounting portions  55 , and the portions where the mounting portions  55  are soldered to the mounting pads  13  are prevented from being broken, whereby a reliable connector assembly can be realized. 
     Moreover, when the second connector  61  is fitted to the first connector  51 , the extension portion  63 F of the second connector  61  passes along the cutout portions  53 D of the first connector  51  and the projection  63 G of the second connector  61  is pressed by the first connector  51  to cause elastic deformation of the extension portion  63 F, thus leading to displacement of the projection  63 G in the +Y direction. Then, when the projection  63 G advances in the +Z direction to pass the upward-facing face  53 C of the first connector  51 , the projection  63 G is no longer pressed by the first connector  51 , and is displaced in the −Y direction to be positioned immediately above the upward-facing face  53 C in the +Z direction, as illustrated in  FIG. 27 . Therefore, even when a force in the −Z direction is exerted on the second connector  61  for some reason, the projection  63 G is caught on the upward-facing face  53 C to limit displacement of the second connector  61  in the −Z direction with respect to the first connector  51 . Therefore, after the second connector  61  is fitted to the first connector  51 , the second connector  61  is prevented from being separated from the first connector  51  in the −Z direction. 
     In the above-mentioned first embodiment, the circuit board  11  is used as the connector holding plate. However, as illustrated in  FIG. 28 , the circuit board  11  attached to other members such as a metallic chassis  91  may also be used as a connector holding plate  81 . 
     The metallic chassis  91  can be fixed to the second face  11 B of the circuit board  11  with an adhesive or a double-faced tape, or through connecting with screws. A through-hole  92  having the same size as the through-hole  12  formed in the circuit board  11  is formed in the metallic chassis  91 . 
     In this case, when the second connector  31  is fitted to the first connector  21  mounted on the circuit board  11  which makes up the connector holding plate  81 , the abutment portion  32 B of the second housing  32  in the second connector  31  comes into abutment against a face of the metallic chassis  91  that is oriented in the −Z direction. Therefore, such a large force as to push up the first connector  21  in the +Z direction is prevented from being exerted on the first connector  21  from the second connector  31 , thus keeping the portions where the first connector  21  is soldered to the circuit board  11  from being broken. 
     However, when the abutment portion  32 B of the second connector  31  is abutted, as illustrated in  FIG. 29 , against the second face  11 B of the circuit board  11  instead of a metallic chassis  93  during the fitting because the metallic chassis  93  fixed to the second face  11 B of the circuit board  11  has a larger through-hole  94  than the abutment portion  32 B of the second connector  31 , only the circuit board  11  serves as the connector holding plate. In other words, as in the first embodiment, the abutment of the abutment portion  32 B of the second connector  31  against the second face  11 B of the circuit board  11  can prevent the portions where the first connector  21  is soldered to the circuit board  11  from being broken. 
     It is also possible to configure the circuit board  71  according to the second embodiment in the same manner as the structure illustrated in  FIG. 28  by using the circuit board  71  attached to a metallic chassis or the like as the connector holding plate so that the abutment portion  64  of the second connector  61  is abutted against the face of the metallic chassis that is oriented in the −Z direction. With such a configuration, the portions where the first connector  51  is soldered to the circuit board  71  can be also prevented from being broken.