Patent Publication Number: US-8529295-B2

Title: Surface mount multi-connector and electronic apparatus having the same

Description:
TECHNICAL FIELD 
     The present invention relates to a surface mount multi-connector connected electrically and an electronic apparatus having a surface mount multi-connector. 
     BACKGROUND ART 
     Japanese Patent Application Laid Open No. 2004-537836 discloses the prior-art one-surface mount multi-connector  10 . The creation method and structure of one-surface mount multi-connector  10  disclosed in this patent literature will be described with reference to  FIG. 1 . 
     First, a plurality of first contacts  12  and a plurality of second contacts  22  are formed by punching a metal plate  90 . Next, the plurality of first contacts  12  and the plurality of second contacts  22  are placed in a cavity, and then molten plastic etc. is injected into the cavity. The plurality of first contacts  12  and the plurality of second contacts  22  are covered with molted plastic, and the molted plastic is solidified into a desired shape to insert-mold a first body  11  having the plurality of first contacts  12  and a second body  21  having the plurality of second contacts  22 . 
     The first body  11  and the second body  21  are disconnected from the metal plate  90 . A concave portion  11   a  of the first body  11  and a projection (not shown) of the second body  21  mate with each other to form a body assembly  31 . Next, a cover  51  is attached to a body cantilever part  34  of the body assembly  31  to form a connector semi-fabricated body  52 . The connector semi-fabricated body  52  is inserted into the mold and a connector housing main body  61  is molded so as to cover part of the first body  11 , the second body  21 , the cover  51 , the first contacts  12  and the second contacts  22 . As shown in  FIG. 1 , the connector housing main body  61  extends downward to the lower end of the connection portions of the first contacts  12  and the second contacts  22 . Finally, a cover  71  is attached. The cover  71  is partially supported by the connector housing main body  61  and encloses both the connector housing main body  61  and an inner cover  51 . 
     This structure allows the connection portions of the first contacts  12  and the second contacts  22  to be placed on the same plane. 
     SUMMARY OF THE INVENTION 
     Since the prior art uses insert molding to secure the first contacts  12  and the second contacts  22  to the first body  11  and the second body  21 , respectively, it is difficult to flexibly respond to the size of the corresponding connector, possibly causing loose connection etc. 
     To prevent such loose connection etc., preload needs to be applied to the first contacts  12  and the second contacts  22  when the first contacts  12  and the second contacts  22  are of movable type. However, because the first body  11  and the second body  21  are created by insert molding, it is difficult to use these bodies to apply preload to the first contacts  12  and the second contacts  22 . 
     Alternatively, in a method of inserting contacts into a molded body using press-fitting instead of insert molding, it is difficult to maintain the coplanarity (uniformity and planarity of the lowest surface of components or pins with respect to the mounting surface) of the connection portions with respect to the printed circuit board. 
     For these reasons, it is difficult to use two bodies to achieve a compact narrow-pitch connector with two rows of contacts while keeping the connection portions of movable contacts on the same plane. 
     An object of the present invention is to provide a surface mount multi-connector that has movable contact sections with high contact reliability and provides high coplanarity for the connection portions. 
     To address the problems described above, a surface mount multi-connector according to an embodiment of the present invention has a first body in which a plurality of first contacts having movable contact sections and end sections that extend oppositely to each other are held by insert molding, a second body in which a plurality of second contacts having movable contact sections and end sections that extend oppositely to each other are held by insert molding, and a third body that incorporates the first body with which the second body has been coupled so that the movable contact sections of the second contacts and the movable contact sections of the first contacts face in the same direction, in which tips ahead of the movable contact sections of the first contacts and tips ahead of the movable contact sections of the second contacts elastically mate with catching parts formed on an inner wall of the third body, and connection portions of the end sections of the first contacts and connection portions of the end sections of the second contacts lie in a same plane. 
     Effects of the Invention 
     The present invention has the effect of providing the movable contact sections with high contact reliability and the connection portions with high coplanarity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows the creation method and structure of a conventional surface mount multi-connector; 
         FIG. 2  is a perspective view showing the front side, right side, and top face of a surface mount multi-connector  100 ; 
         FIG. 3  is a perspective view showing the back side, left side, and bottom face of the surface mount multi-connector  100 ; 
         FIG. 4  is an exploded perspective view showing the front side, right side, and top face of the surface mount multi-connector  100 ; 
         FIG. 5  is a perspective view showing the front sides, right sides, and top faces of a first body and first contacts; 
         FIG. 6  is a perspective view showing the front sides, right sides, and bottom faces of a second body and second contacts; 
         FIG. 7  is a perspective view showing the front side, right side, and top face of the first body with which the second body has been coupled; 
         FIG. 8  is a perspective view showing the back side, left side, and top face of a third body; 
         FIG. 9  is a bottom view of the surface mount multi-connector  100 ; 
         FIG. 10  is a perspective view showing the cross section p-p′ in  FIG. 9 ; 
         FIG. 11  is an enlarged view of the part enclosed by the dotted line in  FIG. 10 ; 
         FIG. 12  is a view showing the state where tips mate with catching parts; 
         FIG. 13  is a view describing the method of mating the tips with the catching parts; 
         FIG. 14  is a right side view of the surface mount multi-connector  100 ; 
         FIG. 15  is a right side view of the surface mount multi-connector  100  when a third cover and the second body in  FIG. 14  are assumed to be transparent; 
         FIG. 16  is a front view of the cross section q-q′ in  FIG. 9 ; 
         FIG. 17  is a perspective view showing the front side, right side, and top face of a first cover; 
         FIG. 18  is a perspective view showing the front side, right side, and bottom face of a second cover; 
         FIG. 19  is a left side view of the cross section r-r′ in  FIG. 9 ; 
         FIG. 20  is a perspective view showing the back side, left side, and bottom face of the third cover; and 
         FIG. 21  is a perspective view showing the surface mount multi-connector  100  mounted on a printed circuit board. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present invention will be described in detail below. 
     Surface Mount Multi-Connector  100   
     A surface mount multi-connector  100  will be described with reference to  FIGS. 2 ,  3 , and  4 . In the surface mount multi-connector  100 , the side facing a printed circuit board is assumed to be the bottom surface and the side into which the corresponding connector is inserted is assumed to be the front side. 
     The surface mount multi-connector  100  includes a first body  110 , a second body  120 , a third body  130 , a first cover  140 , a second cover  150 , and a third cover  160 . 
     A plurality of the first contacts  112  are arranged in the first body  110  made of synthetic resin such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), etc. and held by insert molding. In the example shown in  FIG. 5 , the first body  110  is substantially rectangular plate shaped. The movable contact sections  112   a  at one end of the first contacts  112  and the end sections  112   b  at the other end extend oppositely to each other from the first body  110 . 
     Similarly, a plurality of the second contacts  122  are arranged in the second body  120  made of synthetic resin such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), etc. and held by insert molding. In the example shown in  FIG. 6  (perspective view seen from the bottom), the second body  120  is substantially rectangular plate shaped. The movable contact sections  122   a  at one end of the second contacts  122  and the end sections  122   b  at the other end extend oppositely each other from the second body  120 . 
     The third body  130  is formed as a molded component made of synthetic resin such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), etc. As shown in  FIG. 7 , the second body  120  is coupled with the first body  110  so that the movable contact sections  112   a  of the first contacts  112  and the movable contact sections  122   a  of the second contacts  122  face in the same direction (toward the front side). In other words, the second body  120  is put on the first body  110 . The first body  110  with which the second body  120  is coupled is inserted and incorporated into the third body  130  shown in  FIG. 8  (perspective view seen from the back side), which is hollow rectangular parallelepiped-shaped. 
     About Preload 
       FIG. 9  is a bottom view of the surface mount multi-connector  100 ;  FIG. 10  is a perspective view showing the cross section p-p′ in  FIG. 9 ;  FIG. 11  is an enlarged view of the part enclosed by the dotted line in  FIG. 10 ;  FIG. 12  shows the state where the tips mate with catching parts. When the first body  110  and the second body  120  are inserted into the third body  130 , the tips  112   c  and  122   c  ahead of the movable contact sections  112   a  and  122   a  of the first body  110  and the second body  120  mate with catching parts  130   a  and  130   b  formed on the inner wall of the third body  130 , respectively. This structure gives preload to each of the movable contact sections  112   a  and  122   a  of the contacts  112  and  122 . 
     One end of the first contact  112  and one end of the second contact  122  are bent toward the connection interface between the first body  110  and the second body  120  to form the movable contact parts  112   a  and  122   a  (see  FIG. 7 ). The first body  110  and the second body  120  are inserted, from the side of the movable contact sections  112   a  and  122   a , into opening  130   d  in the surface (back side) opposite to the an insertion opening  130   c  (see  FIG. 2 ) of the hollow rectangular parallelepiped-shaped third body  130  (see  FIGS. 4 ,  7 , and  8 ). The corresponding connector is inserted into the insertion opening  130   c  (see  FIG. 2 ). Grooves  130   e  and  130   f  are formed in the inner surface of the third body  130 . The inner surface faces the surfaces of the first body  110  and the second body  120 . The Grooves  130   e  and  130   f  are formed so as to face the first contacts  112  and the second contacts  122 , respectively. The ends of the grooves  130   e  and  130   f  on the side of the insertion opening  130   c  are covered with the parts present on the same surface as the inner surface of the third body  130 . The cover parts are the catching parts  130   a  and  130   b  (see  FIGS. 11 and 12 ). 
     When the movable contact sections  112   a  and  122   a  are not loaded, the tips  112   c  and  122   c  are located inside the catching parts  130   a  and  130   b  as shown by the chain double-dashed lines in  FIG. 13 . Before the first body  110  and the second body  120  are inserted into the third body  130 , a jig  94  is inserted into the insertion opening  130   c . The jig  94  mates with the movable contact sections  112   a  and  122   a , and lets the movable contact sections  112   a  and  122   a  elastically deform outward, as indicated by the dashed lines in  FIG. 13 . After the first body  110  and the second body  120  are inserted, the jig  94  is removed from the insertion opening  130   c . The tip  112   c  of each of the first contacts  112  and the tip  122   c  of each of the second contacts  122  are press-fit and elastically mate with the catching parts  130   a  and  130   b , respectively, as shown by the solid lines in  FIG. 13 . That is, preload is applied to each of the movable contact sections  112   a  and  122   a  of the first contacts  112  and the second contacts  122 . The preload may be increased by slightly bending middle parts near the movable contact sections  112   a  and  122   a  toward the connection interface between the first body  110  and the second body  120  at bending points  112   e  and  122   e  in the first contacts  112  and the second contacts  122 , respectively. 
     About Coplanarity 
     A surface  96  (referred to below as the mounting surface  96 ) of the surface mount multi-connector  100  faces the printed circuit board during mounting. The mounting surface  96  is parallel to the surface of the first body  110  opposite to the second body  120  and is out of contact with the first body  110 , in this example.  FIG. 14  is the right side view of the surface mount multi-connector  100 ;  FIG. 15  is a right side view of the surface mount multi-connector  100  when the third cover  160  and the second body  120  in  FIG. 14  are assumed to be transparent. 
     The end sections  112   b  of the first contacts  112  and the end sections  122   b  of the second contacts  122  are bent toward the mounting surface  96  at the back side of the first body  110  and the second body  120 , respectively, and then bent backward on the mounting surface  96  to form connection parts  112   d  and  122   d . At this time, the connection parts  112   d  and  122   d  are present on the same surface (the mounting surface  96 ). As shown in  FIG. 9 , the first contacts  112  and the second contacts  122  are displaced in the right and left direction seen from the direction (y-axis direction) in which the second body  120  is coupled with the first body  110 . In addition, the positions of the connection parts  112   d  and  122   d  on the mounting surface  96  are displaced in the back and forth direction. 
     When, for example, the first contacts  112  and the second contacts  122  are formed by punching a metal plate, the coplanarity of the connection parts  112   d  and  122   d  with respect to the mounting surface  96  can be improved. 
     Details of the First Body  110   
     In this example, there is a thick section  110   b  on the surface facing the mounting surface  96  at the end of the first body  110  from which the end sections  112   b  extend (see  FIG. 5 ). Although not shown in the drawing, the first contacts  112  are insert-molded so that one surface of each of the first contacts  112  is exposed on the same surface as the surface of each of plate sections  110 A and  110 B of the first body  110  facing the mounting surface  96 . 
     In this example, a plurality of projections  110   c  are arranged in the direction in which the first contacts  112  are arranged, on the front side (surface facing the insertion opening for the corresponding connector) of the thick section  110   b  of the first body  110 . 
     Details of the Second Body  120   
     On the other hand, there is a thick section  120   b  on the surface opposite to the mounting surface  96  at the end of the second body  120  from which the end sections  122   b  extend (see  FIGS. 6 and 7 ). Side walls  120   c  are formed integrally with the second body  120  on both sides of the thick section  120   b  in the direction in which the second contacts  122  are arranged so as to extend toward the mounting surface  96 . A projection  120   e  is formed on the front surface (surface facing the insertion opening for the corresponding connector) of the side wall  120   c . It is desirable to provide projection  120   e  in a position between the mounting surface  96  and the surface of the second body  120  facing the first body  110 . 
     In addition, there is a second thick section  120   j , which is thicker, in the back than in the front of the thick section  120   b , on the surface facing the mounting surface  96 , at the end of the second body  120  from which the end sections  122   b  extend (see  FIG. 6 ). 
     The second contacts  122  are insert-molded so that one surface of each of the second contacts  122  is exposed on the same surface as the surface of each of plate sections  120 A and  120 B of the second body  120  opposite to the mounting surface  96  (see  FIG. 7 ). 
     Details of Installation 
     As shown in  FIG. 7 , when the second body  120  is coupled with the first body  110 , the thick section  110   b  of the first body  110  is sandwiched between the side walls  120   c . The back side of the thick section  110   b  of the first body  110  makes contact with the front side of the second thick section  120   j  of the second body  120 . The top face of the thick section  110   b  of the first body  110  makes contact with the bottom face of the thick section  120   b  of the second body  120 . The side of the thick section  110   b  of the first body  110  makes contact with the inner side of the side wall  120   c  of the second body  120 . The front side of the thick section  110   b  of the first body  110  and the front sides of the thick section  120   b  and the side wall  120   c  of the second body  120  are present on the same plane. At this time, the surface of the thick section  110   b  facing the mounting surface  96  and the surfaces of both side walls  120   c  facing the mounting surface  96  preferably come close to the mounting surface  96 . 
     When the first body  110  with which the second body  120  has been coupled is inserted into the third body  130 , the front sides of the thick sections  110   b  and  120   b  and the front sides of side walls  120   c  make contact with the back side of the third body  130 . Accordingly, the surfaces of the first body  110  other than the surface facing the mounting surface  96  make contact with the second body  120  or the third body  130 . Since the first body  110  is enclosed by the second body  120  and the third body  130 , securing the second body  120  to the third body  130  secures the first body  110 . This structure eliminates means for securing the first body  110  to the third body  130 , thereby simplifying the component shape. 
     In this example, concave portions  130   g  and  130   h  are formed on the back side of the third body  130 . The projections  110   c  and  120   e  are inserted into the concave portions  130   g  and  130   h , respectively. The insertion of the projections  110   c  and  120   e  into the concave portions  130   g  and  130   h  determines the relative positions of the first body  110 , the second body  120 , and the third body  130 . 
     The relative positions of the first body  110 , the second body  120 , and the third body  130  may be determined by forming concave portions instead of projections  110   c  and  120   e  in the same positions, forming projections instead of the concave portions  130   g  and  130   h  in the same positions, and mating these projections with concave portions. That is, it is enough to dispose positioning means using concave and convex mating on the back side of the third body  130  and the surfaces on the first body  110  and the second body  120  that make contact with the back side. This structure surely positions the first body  110 , the second body  120 , and the third body  130 . 
     Two-Headed Plug 
     In this example, there are two insertion openings  130   c  in the third body  130  (see  FIG. 2 ). Accordingly, the part of the first body  110  to be inserted into the third body  130  is separated into the plate sections  110 A and  110 B, as shown in  FIG. 5 . The plate sections  110 A and  110 B are formed integrally with each other via a connection part  110   h , which is an extension of the thick section  110   b . In this example, the projections  110   c  are formed at the front of the connection part  110   h.    
     As shown in  FIG. 6 , the part of the second body  120  to be inserted into the third body  130  is also separated into the plate sections  120 A and  120 B. The plate section  120 A is connected to the plate section  120 B via a connection part  120   h , which is located behind the thick section  120   b . The front sides of the connection part  120   h  and the second thick section  120   j  are present on the same plane. The connection part  120   h  is formed by bending a stripe plate into U-shape. The two legs of the connection part  120   h  are connected to the two thick sections  120   b  on both sides. The middle section of the connection part  120   h  is located closer to the mounting surface  96  than the surface of each of the plate sections  120 A and  120 B of the second body  120  that faces the mounting surface  96 . The leg of the connection part  120   h  on the side of plate section  120 B extends upward until it reaches the height of the thick section  120   b  (see  FIG. 7 ). 
     An angular projection  110   i , which extends away from the mounting surface  96 , is formed integrally with the connection part  110   h  of the first body  110 . The back side of the angular projection  110   i  makes contact with the front side of the leg on the side of the plate section  120 A of the connection part  120   h  (see  FIG. 7 ). This structure suppresses rattles in the vertical and horizontal directions even when the width of the two-headed plug increases. 
     The third body  130  includes two hollow rectangular parallelepiped-like parts  130 A and  130 B. The plate sections  110 A and  120 A are inserted in the hollow rectangular parallelepiped-like part  130 A. The plate sections  110 B and  120 B are inserted in the hollow rectangular parallelepiped-like part  130 B. The hollow rectangular parallelepiped-like parts  130 A and  130 B are connected integrally with each other through a connection part  130   i  at their backs (see  FIG. 8 ). 
     This structure allows the two-headed plug-shaped connector to be designed using the same number of components. 
     Ridges  110   g  and  120   g    
     In this example, the first body  110  and the second body  120  are press-fits into the third body  130  with a force applied in the superimposition direction and the movable contact sections  112   a  and  122   a  are positioned in the superimposition direction. 
     At this time, at least one slim and low ridge  110   g  extending in the body insertion direction is desirably formed on the surface of the first body  110  opposite to the second body  120  integrally with the first body  110 , and at least one slim and low ridge  120   g  extending in the body insertion direction is desirably formed on the surface of the second body  120  opposite to the first body  110  integrally with the second body  120  (see  FIGS. 5 and 6 ). In this example, two ridges  110   g  are spaced apart on each of the plate sections  110 A and  110 B of the first body  110  and two ridges  120   g  are spaced apart on each of the plate sections  120 A and  120 B of the second body  120 . 
     As shown in  FIG. 16 , in this example, it is desirable that the two ridges  110   g  disposed on each of the plate sections  110 A and  110 B of the first body  110  are sandwiched between the two ridges  120   g  disposed on each of the plate sections  120 A and  120 B of the second body  120 . In addition, the interval of the ridges  110   g  or  120   g  on each plate section is desirably the same.  FIG. 16  shows the cross section q-q′ in  FIG. 9 . 
     When the first body  110  and the second body  120  make contact with each other through their surfaces, if the flatness of the first body  110  and the second body  120  is large, interference may be caused. In addition, the clearance between the first body  110  with which the second body  120  has been coupled and the third body  130  is small, so it is difficult to insert the first body  110  with which the second body  120  has been coupled into the third body  130 . With the structure in this example, the clearance between the first body  110  and the second body  120  can be embedded, thereby enabling positioning in the vertical direction. Even if interference between the first body  110  and the second body  120  through their mutually facing surfaces occurs, the ridges  110   g  or  120   g  are crushed to enable positioning. 
     First Cover  140   
     The third body  130  is covered with the first cover  140  and the second cover  150 , which are made of metal. In this example, the hollow rectangular parallelepiped-like parts  130 A and  130 B of the body  130  are covered with the first cover  140  and the second cover  150 , respectively. 
     As shown in  FIG. 17 , the first cover  140  is created by forming a metal plate into a hollow rectangular parallelepiped. The hollow rectangular parallelepiped-like part  130 A of the third body  130  is inserted into the first cover  140 . 
     A surface of the first cover  140  that is in parallel with and more distant from the mounting surface  96  extends to the rear end of the second body  120  to form a fixing extension  140   b . The fixing extension  140   b  extends to the rear end of the second body  120  along the surface of the second body  120  and the third body  130 , which is in parallel with the mounting surface  96 , and more distant from the mounting surface  96 . Locking pieces  140   d  are formed on both sides at the back of the fixing extension  140   b . The locking pieces  140   d  are bent toward the mounting surface  96 . The first body  110  and the second body  120  are surely secured to the third body  130  by mechanically swaging the locking pieces  140   d.    
     Second Cover  150   
     As shown in  FIG. 18 , the second cover  150  is formed by bending a metal plate into U-shape. One leg of the second cover  150  is extended backward to form a fixing extension  150   b.    
     An opening  150   c  into which the corresponding connector is inserted is formed in the center. The second cover  150  is attached so as to clamp and cover the hollow rectangular parallelepiped-like part  130 B of third body  130 . 
       FIG. 19  shows the cross section r-r′ in  FIG. 9 . A groove  130   j  is disposed in the external surface of the hollow rectangular parallelepiped-like part  130 B of third body  130  that faces the mounting surface  96 . The groove  130   j  is covered at the end (back wall) to form a small engaging hole  130   k.    
     Small locking pieces  150   k  are formed on both sides of the other leg (on the side of the mounting surface  96 ) of the U-shaped second cover  150 . Each of the small locking pieces  150   k  is engaged in the small engaging hole  130   k . This structure prevents the second cover  150  from opening downward. 
     The fixing extension  150   b  is parallel with the mounting surface  96  and configures the surface that is more distant from the mounting surface  96 . The fixing extension  150   b  extends to the rear end along the surface of the second body  120  and the third body  130 , which is in parallel with the mounting surface  96 , and more distant from the mounting surface  96 . 
     A locking piece  150   d  is formed in the middle at the extending end of the fixing extension  150   b . The locking piece  150   d  is bent toward the mounting surface  96 . The first body  110  and the second body  120  are surely secured to the third body  130  by mechanically swaging the locking piece  150   d.    
     The third body  130  is covered with the metal covers as described above to obtain shield effects. In this example, the hollow rectangular parallelepiped-like parts  130 A and  130 B of the third body  130  are covered with the first cover  140  and the second cover  150 , which are mutually different components. This structure enables one shield cover (first cover  140 ) that covers four sides. The plug covered by the shield cover that covers four sides can be used as a transmission and reception plug for high-speed transmission signals. 
     Tapered Locking Parts  130   p  and  130   m  and Rectangular Openings  140   j  and  150   m    
     In this example, low tapered locking parts  130   p  and  130   m  are formed on the external surfaces of the hollow rectangular parallelepiped-like parts  130 A and  130 B of the third body  130  that are opposite to the mounting surface  96  (see  FIG. 8 ). When the tapered locking parts  130   p  and  130   m  that increase in height toward their backs are covered with the first cover  140  and the second cover  150 , respectively, the tapered locking parts  130   p  and  130   m  are inserted into rectangular openings  140   j  and  150   m  disposed on the fixing extensions  140   b  and  150   b . This structure prevents the covers from being removed forward ( FIGS. 17 and 18 ). 
     Third Cover  160   
     As shown in  FIGS. 2 and 20 , the third cover  160  covers the fixing extensions  140   b  and  150   b  of the first cover  140  and the second cover  150 . The third cover  160  covers a surface of the second body  120  and the third body  130 , which is orthogonal to the mounting surface  96 , and parallel to the contacts. In addition, legs  160   a  project orthogonally to the mounting surface  96  on the both sides of the third cover  160 . 
     In this example, legs  160   a  project in the front and back positions on both sides of the third cover  160 . As shown in  FIG. 21 , the legs  160   a  are connected by soldering etc. to secure the surface mount multi-connector  100  to a printed circuit board  210 . 
     The side wall of the third body  130  on the side of the hollow rectangular parallelepiped-like part  130 B is bent from the back end to the front and then extends forward to form a locking piece  160   b . A locking nail  160   c , which is bent externally, is formed at the tip of the locking piece  160   b.    
     In addition, both arms  160   d  and  160   e  of a U-shaped stripe plate are spaced apart along the external surface of the third cover  160 . The U-shaped stripe plate is bent at a middle point  160   f  along the side wall of the hollow rectangular parallelepiped-like part  130 B. The arm  160   d  near the back side is connected to the back end of the third cover  160 . The end of the arm  160   e  extends to a notch  160   g  which is formed in the middle of the third cover  160 . The arm  160   e  is then bent toward the mounting surface  96 . The arm  160   e  extends forward in a path between the bodies to form a locking piece  160   h . The tip of the locking piece  160   h  is bent externally to form a locking nail  160   i.    
     Lower tapered locking parts  130   n  are formed on both sides of the third body  130  (see  FIG. 8 ). When a third cover  160  is put over the lower tapered locking parts  130   n , which increases in height toward the front, from the back to the front, the tapered locking parts  130   n  are inserted into rectangular openings  160   m  disposed on the side walls of the third cover  160 . This structure prevents the third cover  160  from being removed backward. 
     A locking piece  160   p  is bent toward the mounting surface  96  in the middle at the back end of the third cover  160 . This structure lets the locking piece  160   p  mate with the back side of the second body  120  and prevents the third cover  160  from being removed forward. 
     Lugs  140   e  and  150   e , which bend obliquely from the back to the front away from the mounting surface  96 , are formed on fixing extensions  140   b  and  150   b , respectively. The lugs  140   e  and  150   e  bring the first cover  140  and the second cover  150  into secure contact with the third cover  160 . 
     The locking piece  160   b  and  160   h  and the locking nails  160   c  and  160   i  constitute latch springs so that the latch springs are formed integrally with the third cover  160 . The locking piece  160   b  and the middle point  160   f  are held and a force is applied to operate the latches. This structure increases the holding force for the unit having the corresponding receptacle, without increasing the number of parts. 
     The third cover  160  can be formed separately with the first cover  140  and the second cover  150 . Accordingly, the third cover  160  may be formed of thicker metal material than in the first cover  140  or the second cover  150 . This structure improves the mounting strength of printed circuit board. Since the plug thickness dimensions are defined for the first cover  140  and the second cover  150 , the thickness of material is limited, thereby making it difficult to obtain a desired strength. 
       FIG. 21  shows the state where the surface mount multi-connector  100  is mounted on the printed circuit board  210  of an electric apparatus. This structure allows the electronic apparatus with a predetermined printed circuit board to use the surface mount multi-connector  100  for connection with another electronic apparatus with the corresponding connector. At this time, the holding force can be increased by providing the corresponding connector with the receptacle that mates with the latch spring formed integrally with the third cover  160 . 
     The present invention is not limited to the above embodiments, and various modifications may be made in the embodiments without departing from the scope of the invention. For example, the surface mount multi-connector  100  may not be two-headed shaped and the shapes of the bodies and covers may be changed as necessary. In addition, the present invention can be practiced without the covers. 
     Effects 
     These structures improve the coplanarity of the connection portions  112   d  and  122   d  of the first and second contacts  112  and  122  with respect to the mounting surface  96 . Since the tips  112   c  and  122   c  of the movable contacts  112   a  and  122   a  of the first and second contacts  112  and  122  mate with catching parts  130   a  and  130   b  of the third body  130  to give preload, the contact reliability can be improved.