Patent Publication Number: US-6665932-B2

Title: SMT connector and method of production of same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a connector and a method of production of the same, more particularly relates to an SMT connector suitable for surface mounting on a printed circuit board and a method of production of the same. 
     2. Description of the Related Art 
     Use of an SMT connector which is surface mounted on a printed circuit board for connection with external circuits has become general practice due to the increasingly smaller size and lighter weight of printed circuit boards in recent years. 
     FIGS. 1A to  1 C are perspective views of a conventional SMT connector, wherein FIG. 1A is a perspective view of an overall connector, FIG. 1B a conductor before processing, and FIG. 1C a conductor after processing, wherein a lead  102  of a single conductor  10  formed with a contact  101  at its front end and formed with a lead  102  at its rear end is bent in a crank shape. 
     The connector is produced by arranging a required number of bent conductors and encasing them by an insulating material or press-fitting processed conductors into an insulator. 
     Summarizing the problems to be solved by the invention, in an SMT connector produced by the above method, however, the problem arises of a deterioration of the coplanarity. 
     FIGS. 2A and 2B are explanatory views of problems arising in a conventional connector. The coplanarity of the leads deteriorates due to the following two reasons: 
     1. As shown by FIG. 2A the coplanarity of the leads deteriorates due to deformation (twisting, warping) of the insulator itself after encasing the conductors or press-fitting the conductors. 
     2. As shown by FIG. 2B, the coplanarity of the leads deteriorates due to the variability of the press-forming accuracy of the leads. 
     Therefore, it was necessary to provide a step of correcting the coplanarity after finishing assembly of the SMT connector so as to improve the coplanarity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein: 
     FIGS. 1A to  1 C are perspective views of a conventional SMT connector; 
     FIGS. 2A and 2B are explanatory views of problems occurring in a conventional SMT connector; 
     FIGS. 3A and 3B are structural views of an SMT connector according to the present invention; 
     FIG. 4 is an explanatory view of a first method of production of an SMT connector; 
     FIG. 5 is an explanatory view of a first secondary bending method; 
     FIG. 6 is an explanatory view of a second secondary bending method; 
     FIG. 7 is an explanatory view of a second method of production of an SMT connector; and 
     FIG. 8 is an explanatory view of a third method of production of an SMT connector. 
    
    
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an SMT connector suitable for surface mounting on a printed circuit board enabling the necessary coplanarity to be secured even without providing a coplanarity correction step after assembly and a method for production of the same. 
     An SMT connector according to a first aspect of the present invention is comprised of a contact member made of a metal having a high hardness, a lead member of a crank shape having one end connected to one end of the contact member and made of a metal having a low hardness, and an insulating material covering a connection part of the contact member and the lead member. 
     An SMT connector according to the present invention is structured of a contact member having a high hardness and a lead member having a low hardness connected together and having a connection part covered by an insulating material. 
     A method of production of an SMT connector according to a second aspect of the invention is comprised of a connecting step of connecting one end of a contact member and one end of a straight-shaped lead member, a covering step of covering the connection part of the contact member and lead member connected in the connecting step by an insulating material, and a bending step of bending the lead member after covering in the covering step. 
     In the present invention, a contact member having a high hardness and a straight-shaped lead member having a low hardness are connected, the connection part is encased, and finally the lead is bent into a crank shape. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described in detail below while referring to the attached figures. 
     FIGS. 3A and 3B are structural views of an SMT connector according to the present invention, wherein FIG. 3A is a perspective view and FIG. 3B is a sectional view along the line X—X. 
     That is, the SMT connector according to the present invention is structured of contact members  31  produced by a material having a high hardness (for example, brass or phosphor bronze) and lead members  32  produced by a material having a low hardness (for example, copper) electrically connected inside an insulating material  33 . 
     FIG. 4 is an explanatory view of a first method of production of an SMT connector according to the present invention. Contact members  31  are press-formed from a metal material by a contact member press  40 . The contact members  31  are formed at equal intervals on a band-shaped contact member carrier  35  so as to enable easy subsequent handling. 
     The contact members  31  are plated in a contact member plating apparatus  41  along with the contact member carrier  35  and taken up on a contact member reel  42 . 
     Lead members  32  are press-formed from a metal material by a lead member press  43 . The lead members  32  are formed at equal intervals on a band shaped lead member carrier  36  so as to enable easy subsequent handling. 
     The lead members  32  are plated in a lead member plating apparatus  44  along with the lead member carrier  35  and taken up on a lead member reel  42 . 
     A connecting machine  46  receives the supply of the contact members  31  from the contact member reel  42  and the lead members  32  from the lead member reel  45  and connects the contact members  31  and lead members  32 . The method of connection is not particularly limited, but welding or crimping is suitable. 
     Further, after connection is finished, the contact member carrier  35  is removed to separate the contact members  31 . 
     The plastic molding machine  47  covers the connection parts of predetermined numbers of contact members  31  and lead members  32  by an insulating material. Next, the lead member carrier  36  is removed to separate the lead members  32  and primary bending is performed to bend the lead members  32  perpendicularly downward. 
     Finally, the secondary bending machine  48  performs secondary bending for bending the front ends of the lead members  32  perpendicularly horizontally. 
     FIG. 5 is an explanatory view of a first secondary bending method. The SMT connector after the primary bending is placed on a bed on the top and bottom surfaces of which two slide dies  51  and  52  slide. 
     That is, when the SMT connector after the primary bending is placed on the bed, the lead members  32  extend to the bottom from the surface of placement. 
     The top surface slider  51  is slid to the back surface of the lead members  32 , then the bottom surface slider  52  is slid so as to bend the front ends of the lead members  32  along the bottom surface of the top surface slider and thereby complete the secondary bending of the lead members  32 . 
     FIG. 6 is an explanatory view of a second secondary bending method. A damper comprised of a slide die  61  and a pair of claws  621  and  622  is provided. 
     The cross-section of the slide die  61  is frustoconical in shape. The sectional shape becomes substantially rectangular when combined with one claw  621  of the damper having an acute angle triangular cross-sectional shape. Note that the sectional shape of the other claw  622  of the damper is rectangular. 
     In the same way as the first secondary bending method, when the SMT connector after the primary bending is placed on the bed, the lead members  32  extend to the bottom from the surface of placement. 
     The downward extending lead members  32  are clamped by the claws  621  and  622 . In that state, the damper is rotated until one claw  621  of the damper strikes the slide die  61 , whereby the secondary bending of the lead members is completed. 
     FIG. 7 is an explanatory view of a second method of production of an SMT connector according to the present invention. The lead members  32  are produced by plating wires by a lead member plating apparatus  44 . 
     In the connecting machine  46 , wire-shaped lead members  32  are connected to the contact members  31  attached to the contact member carrier  35 , then the lead members  32  are cut to predetermined lengths. 
     Next, in the plastic molding machine  47 , first the contact member carrier  35  is removed to separate the contact members  31 , then the connection parts of the contact members  31  and lead members  32  are encased by a resin. 
     The rest of the production process is identical to the first method of production. 
     FIG. 8 is an explanatory view of a third method of production of an SMT connector according to the present invention. In the same way as the second method of production, the lead members  32  are wire shaped. 
     In the connecting machine  46 , unlike the explanatory view of the second method of production, first the wire-shaped lead members  32  are cut to predetermined lengths, then are connected to the contact members. 
     The rest of the production process is identical to the second method of production. 
     Summarizing the effects of the invention, according to the present invention, since the SMT connector is produced by connecting contact members having a high hardness and lead members having a low hardness, covering the connection parts by an insulating material, and bending the lead members into a crank shape, it becomes possible to maintain the required coplanarity of the lead members even without proving a correction step. 
     While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention. 
     The present disclosure relates to subject matter contained in Japanese Patent Application No. 2001-151236, filed on May 21, 2001, the disclosure of which is expressly incorporated herein by reference in its entirety.