Patent Publication Number: US-2011076894-A1

Title: Lower profile electrical socket configured with wafers

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the art of electrical socket. Specially, the present invention provides a lower profile electrical socket with wafers assembled therein each having a number of contacts located therein from art of insertion molding. 
     2. Description of Prior Art 
     Generally speaking, a socket to which the present invention is related is interposed between a first and a second electronic part or components having contact pads, respectively, to achieve electrical connection between the first and the second electronic components. In the following description, the first and the second electronic components are directed to a printed board and a Large Scale Integrated circuit (LSI), respectively. The socket comprises an insulative housing provided with a plurality of contact receptacle holes penetrating the insulator in a thickness direction, and a plurality of elastic contacts inserted into and held in the contact receptacle holes, respectively. In the conventional electrical connectors, housings are usually molded by an injection molding art. 
     As a result, after the socket is formed, contacts are inserted in a column-row configuration on the housing of the electrical connector. In addition, when the industry trend is to obtain highest quantity of contacts on the electrical socket, the housing of the electrical socket needs to receive more terminals therein for getting a better electrical connection and transmitting more signals, the number of passageways formed on the housing needs be increased correspondingly which leads the housing difficultly to be molded. Moreover, the conventional socket cannot meet need of trend of miniaturization and multiple contact points freely. Moreover, in order to get a contact layout of miniaturization and multiple contact points, multiple contacts need to be inserted into the original housing. Obviously, the traditional contact insertion process can be hardly used in the fine pitch and low profile socket connector. 
     In view of the above, an improved electrical socket that overcomes the above-mentioned disadvantages is desired. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an electrical socket with a plurality of wafers assembled therein. Each wafer has a number of contacts molded therein from an injected art. 
     To achieve the above-mentioned object, The present invention relates to an electrical socket comprising a plurality of wafers arranged with one another in a first direction and in a parallel relation, and a constraining device holding the wafers in position so as to maintain said wafers in a parallel manner. Each wafer is molded by an injected art with a number of contacts molded therein. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric, assembled view of an electrical socket in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is similar to  FIG. 1  showing an assembled view of the electrical socket of the present invention from another view; 
         FIG. 3  is an isometric, exploded view of the electrical socket of  FIG. 1 ; 
         FIG. 4  is an isometric, exploded view of the electrical socket of  FIG. 2 ; 
         FIG. 5  is an isometric view showing a contact strip with a number of contacts thereon; 
         FIG. 6  is an isometric view showing a wafer having a contact strip being ready to be assembled with a frame of the electrical socket of the present invention; and 
         FIG. 7  is a top view of the electrical socket of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
     Reference will now be made to the drawings to describe the present invention in detail. 
     Referring to  FIGS. 1-6 , the electrical socket  100  of the present invention is used for electrically connecting an LSI package (not shown) to a PCB (not shown), comprising a frame  1 , a plurality of wafers  2  each molded with a plurality of contacts  20  therein. Each contact  20  has a solder ball  3  attached on a bottom portion thereon. The solder ball  3  will be soldered on the bottom portion of the contact  20  after the wafers  2  are assembled into the frame. 
     Referring to  FIGS. 1-4 , the frame  1  defines an upper face  10 , a lower face  11  opposite to the upper face  10 . A supporting portion  12  is recessed downward from a middle portion of the upper face  10 . The supporting portion  12  defines a supporting surface  120  below the upper face  10  of the frame  1  in an up-to-down direction. The supporting portion  12  further defines an opening  12  through both the supporting surface  120  and the lower face  11 . The opening  12  defines a plurality of slots  14  at opposite inner walls thereof. Correspondingly, a plurality of interior walls  15  is formed between two adjacent slots  14 . 
     Referring to  FIGS. 3-6 , each wafer  2  has a base  21  with a plurality of contacts  20  received therein. The contacts  12  and the corresponding base are integrated molded by an injection art. The contacts  12  are formed by art of stamping from a contact strip  4  before molded with the base  21 . 
     Each contact  20  comprises a retaining portion  200  extending in a vertical direction, a solder portion  201  formed at a bottom portion of the retaining portion  200 , a first arm extending upwardly from a side of a top end of the retaining portion  200 , a curving second arm  2021 , and a third arm  2022  extending upwardly from the second arm  2021 . A contacting portion  203  is formed at a tail end of the third arm  2022  for engaging with the LSI package. A notch  2001  is formed at a middle portion of an edge of the retaining portion  200  and a slanting surface  2002  extending toward the first arm  2020  is formed at an edge of the top end of the retaining portion  200 . The second arm  2021  has a top end A, which is higher than the supporting surface  120  of the frame  1  when the contacts  12  is received in the frame  1 . 
     In an assembly process, at first, the base  21  and a plurality of contacts  12  form the wafer by injection molding art. A sloping surface  212  is formed on an upper surface  210  of the base  21 . The base  21  further defines an opening  213  recessed both from one of sidewalls and the lower surface  211  of the base  21 . Secondly, the plurality of wafers  2  is inserted into the slots  14  of the frame  1  from a lower face  11 , respectively. At last, the contact strips  4  are cut off and removed from corresponding wafers  2 . 
     After the assembled process done, the top end A of the contact  12  extend beyond the supporting surface  120  for engaging with the IC package. The plurality of wafer  2  is arranged with one another in a first direction in a parallel relation. All contacts  12  are arranged in rows along the first direction and columns along a second direction perpendicular to the first direction. Referring to  FIG. 7 , all contacts are arranged in a manner of one contact of corresponding row offset from an adjacent contact of an adjacent corresponding row in the column direction. Specially, the one contact of corresponding row is aligned with another contact of anther corresponding row in the column direction, which is neighboring the adjacent corresponding row. In another word, after the assembling process is done, the wafers  2  are grouped with a first type and a second type. The contacts in a wafer  2  of a first type are offset from contacts located in a wafer  2  of a second type along the second direction in each column. Moreover, the wafers of first type and second type are alternately arranged with one another in the column direction. Accordingly, referring to  FIGS. 1 and 3 , a solder cavity is formed by the opening  213  and sidewall of an adjacent wafer  2 . 
     According to the present invention, the socket holds the contacts by the wafers. The contacts and the wafer are formed from the insertion-molding process. As we know, there are no passageways for receiving the contacts in such wafer. Thus, a high density of layout of the contacts may be achieved easily by such art. Accordingly, an electrical socket having a high-density contacts layout is provided. 
     While the preferred embodiment in accordance with the present invention has been shown and described, equivalent modifications and changes known to persons skilled in the art according to the spirit of the present invention are considered within the scope of the present invention as defined in the appended claims.