Patent Publication Number: US-2011059633-A1

Title: Surface mount contact

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to conducting terminals and more particularly, to a surface mount contact for surface mounting application. 
     2. Description of the Related Art 
     Uneven PC board surface leveling and poor coplanar condition of electronic component pins may be encountered when bonding an electronic component to a PC board by means of a surface mounting technique. U.S. Pat. No. 6,700,079, as shown in  FIG. 1 , and U.S. Pat. No. 7,537,498, as shown in  FIG. 2 , disclosure measures to eliminate the aforesaid problems. 
     According to the design shown in  FIG. 1 , the surface mount contact comprises a pin  1 , an insulator  2  surrounding the shaft of the pin  1 , and a solder ball  3  wrapped about the bottom end of the pin  1  and connected to the bottom side of the insulator  2 . Because of limited space between the solder ball  3  and the bottom end of the pin  1 , the user cannot judge the distribution status and quality of the melted solder ball  3  around the pin  11  during surface bonding. 
     According to the design shown in  FIG. 2 , the surface mount contact comprises a conductive pin  4 , a heat re-flowable bonding member  6  coupled to one end of the conductive pin  4  and conductive locator member  5  disposed around the conductive pin  4  between the two opposite ends of the conductive pin  4 . The conductive locator member  5  serves as a locating member to limit the degree of travel of the conductive pin  4  within the bore of the PC board. When the heat re-flowable bonding member  6  is melted, the melted heat re-flowable bonding member  6  is freely distributed over the surface of the conductive pin  4  beneath the conductive locator member  5 . However, because the size of the heat re-flowable bonding member  6  is not easy to control, it is difficult to control the distribution area of the melted heat re-flowable bonding member  6  around the conductive pin  4 , resulting in bonding instability between the surface mount contact and the PC board. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a surface mount contact, which enables the user to judge the solder distribution status and quality on the conducting pin. 
     It is another object of the present invention to provide a surface mount contact, which assures bonding stability. 
     To achieve these and other objects of the present invention, a surface mount contact comprises a surface mount contact includes a conducting pin having a shank, a first end at one end of the shank and second end at the other end of the shank, a first annular flange extending around the periphery of the shank and spaced between the first end and the second end and a second annular flange extending around the periphery of the shank and spaced between the second end and the first annular flange, and a thermoplastic connection member joined to the second end of the conducting pin and spaced from the second annular flange at a predetermined distance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic drawing of a surface mount contact according to the prior art. 
         FIG. 2  is a schematic drawing of another structure of surface mount contact according to the prior art. 
         FIG. 3  is a front view of a surface mount contact in accordance with the present invention. 
         FIG. 4  is a sectional view of the surface mount contact in accordance with the present invention. 
         FIG. 5  is a schematic drawing showing an application example of the surface mount contact in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 3 and 4 , a surface mount contact  10  in accordance with the present invention is shown comprising a conducting pin  11  and a thermoplastic connection member  12 . 
     The conducting pin  11  comprises a shank  111  having a first end  112  at its one end of the shank  111  and a second end  113  its other end, a first annular flange  114  extending around the periphery of the shank  111  and spaced between the first end  112  and the second end  113  and a second annular flange  115  extending around the periphery of the shank  111  and spaced between the second end  113  and the first annular flange  114 . According to the present preferred embodiment, the shank  111 , the first annular flange  114  and the second annular flange  115  are made from one same material in integrity by means of a single piece processing technique, for example, lathe processing technique. Further, the shank  111  can be configured to provide any cross section shape, such as circular, rectangular or oval shape. 
     The thermoplastic connection member  12  is joined to the second end  113  of the conducting pin  11  and kept away from the second annular flange  115  at a predetermined distance d. According to the present preferred embodiment, the thermoplastic connection member  12  is a spherical member prepared from a metal material, for example, solder ball. 
     After understanding of the structural features of the present invention, the application of the surface mount contact  10  is explained hereinafter. Fixedly fasten the surface mount contact  10  to an upper board (circuit board)  20  by means of bonding the part of the shank  111  of the conducting pin  11  between the first end  112  and the first annular flange  114  to the upper board (circuit board), and then melt the thermoplastic connection member  12  to bond the second end  113  of the conducting pin  11  to a solder pad  211  at a lower board (circuit board)  21 , thereby fixing the relative position between the upper board  20  and the lower board  21 . It is to be understood that the first annular flange  114  and the second annular flange  115  are formed around the periphery of the shank  111  at different elevations, the melted thermoplastic connection member  12  will be stopped by one side of the second annular flange  115  that is disposed close to the second end  113  during bonding, and there is a room for the user to judge the connection status and quality between the conducting pin  11  and the thermoplastic connection member  12  and to control the bonding area between the thermoplastic connection member  12  and the conducting pin  11  during surface mounting. 
     As stated above, the surface mount contact  10  of the present invention has the following advantages and features: 
     1. There is a room for the user to judge the connection status and quality between the conducting pin  11  and the thermoplastic connection member  12  during surface mounting. Based on the design of the first annular flange  114  and the second annular flange  115 , there is a room for the user to judge the connection status and quality between the conducting pin  11  and the thermoplastic connection member  12  during surface mounting. 
     2. High bonding stability between the circuit board and the surface mount contact. Because the melted thermoplastic connection member  12  will be stopped by one side of the second annular flange  115  that is disposed close to the second end  113  during bonding, the bonding area between the thermoplastic connection member  12  and the conducting pin  11  is fixed, assuring a high level of bonding stability.