Patent Publication Number: US-8974236-B2

Title: Low profile electrical connector

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the invention 
     The present invention relates to an electrical connector for electrically connecting a Central Processing Unit (CPU) to a printed circuit board (PCB), especially to a low profile electrical connector. 
     2. Description of Related Art 
     Central Processing Unit (CPU) electrical connectors are widely used for establishing electrical connection between the CPU and a printed circuit board (PCB). Therefore, CPU connectors are mounted on motherboards and hold CPUs execution of programs. Sever types of CPU connectors are available with different structures. For example, a type of land grid array (LGA) socket is found in U.S. Pat. No. 7,074,048 issued to Liao et al. (hereinafter “Liao”) on Jul. 11, 2006. Liao discloses a LGA socket including an insulative housing having a plurality of passageways passing through a top surface to a bottom surface of the insulative housing. Each passageway accommodates a terminal which includes a base portion positioned in a vertical direction, an elastic arm extending upwardly from the base portion and a solder portion bent horizontally from a bottom of the base portion. The base portion has a plurality of barbs on two opposite sides thereof for engaging with sidewalls of the passageway to secure the contact in the passageway. A solder ball is soldered on a bottom surface of the solder portion for electrically connecting with the PCB. 
     The contact is received in the passageway by the barbs which causes the height of the contact must be increased so as to unfavorable to low profile of the electrical connector. 
     Hence, it is desirable to provide an improved electrical connector to overcome the aforementioned disadvantages. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a lower profile electrical connector with a low contact. 
     According to one aspect of the present invention, there is provided an electrical connector for electrically connecting a central processing unit (CPU) to a printed circuit board (PCB), comprising a housing, a plurality of contacts, and a plurality of solder balls. The housing has a plurality of passageways extending passing through the housing and a plurality of protrusions located outside the passageways and corresponding the passageways one-to-one. A plurality of contacts partially are disposed in the passageways and each has a hole to match with the protrusion and secure the contacts on the housing. A plurality of solder balls are connected with corresponding contacts. 
     According to another aspect of the present invention, there is provided an electrical connector, comprising a housing with a plurality of passageways. A plurality of contacts are partially received in corresponding passageways. Each contact has a base portion fixed on the housing and not positioned in the passageway. A plurality of solder balls are connected with corresponding contacts and located just below the base portion. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded, perspective view of an electrical connector in accordance with the present invention; 
         FIG. 2  is an assembled, perspective view of the electrical connector shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of  FIG. 2  taken from below; 
         FIG. 4  is a perspective view of  FIG. 1  taken from below; and 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the drawings to describe the present invention in detail. 
       FIGS. 1-3  illustrate an electrical connector of the present invention for electrically connecting a CPU (central processing unit) to a PCB (printed circuit board). The electrical connector comprises an insulative housing  2 , a plurality of contacts  3  received in the housing  2  and a plurality of solder balls  4  clamped by the contact  3  and the housing  2 . 
     Referring to  FIGS. 1 and 5 , each contact  3  includes a horizontally base portion  31  with a hole  310 . The base portion  31  having a substantially circle shape is concentric with the hole  310 . A spring portion  33  extends upwardly and inwardly from the base portion  31  and is substantially positioned upon the base portion  31  seeing from a side view. A tail portion  32  extends downwardly from the base portion  31  and is substantially positioned at a side of the base portion  31  seeing from a side view. The tail portion  32  has an incline portion  320  extending inwardly from the tail portion  32 . The spring portion  33  and the tail portion  32  are located at two side of the base portion  31 , and while located at a centre line of the base portion  31 . A carrier strip linking section  34  is supported at the base portion  31  and extends upwardly for assembling the contact  3  to the housing  2 . 
     Referring to FIGS.  1 , 3 , 4  and  5 , the housing  2  has a cavity  20  having a receiving/supporting surface  21 . The receiving surface  21  of the cavity  20  has a plurality of protrusions  23  extending upwardly therefrom and a plurality of passageways  24  passing through the receiving surface  21  and a bottom surface  22  of housing  2 . The protrusion  23  is use for alignment and retention the contact  3 . Each passageway  24  is located at a side of the corresponding protrusion  23  to allow the tail portion  32  passing through thereof. A plurality of receiving recesses  25  are defined at the bottom surface  22  of the housing  2  and communicate with corresponding passageways  24  for receiving the solder balls  4 . Each recess  25  defines a resisting surface  250  substantially just below the protrusion  23  to resist the solder ball  4  moving upwardly in a vertical direction, furthermore, the inclined portion  320  and edge of the recess  25  to clamp the solder ball  4  so as to prevent the solder ball  4  to fall of the recess  25 . The receiving surface  21  of cavity  20  further has a plurality of posts  26  extending upwardly and higher than the protrusions  23  for supporting the CPU. The posts  26  flush with a top surface of the housing  2 . 
     Referring to  FIGS. 2 and 5 , the hole  310  of the base portion  31  is aligned and interference with the protrusion  23  so as to secure the contact  3  on the housing  2 , and under that condition, the base portion  31  is seated on the receiving surface  21  of cavity  20  while the base portion  31  is substantially located just above the solder ball  4  taken from the side view so as to achieve a low profile contact  3 . The spring portion  33  extends beyond the top surface of the housing  2  so as to electrically connect with the CPU. The protrusion  23  is lower than the spring portion  33  and has some distance with the spring portion  33  in a vertical direction. The protrusion  23  in this embodiment has a hexagon shape and the hole  310  in this embodiment has a circle shape, but understandably, the protrusion  23  also could be a circular shape, rectangular shape, a triangular shape, or other shape, as well as the hole  310  also could be changed to rectangular shape or other shape if so needed. Understandably, the hole  310  of the base portion  31  and the protrusion  23  on the receiving surface  21  are deemed as mutually interengaging structures to secure the contact  3  on the housing  2 . 
     In the present invention, the cavity  20  is defined for reducing the height of the connector and the contact. Clearly, the cavity  20  also could be eliminated such that the protrusions  23  and the posts  26  are disposed on the top surface of the housing  2 . 
     Although the present invention has been described with reference to particular embodiments, it is not to be construed as being limited thereto. Various alterations and modifications can be made to the embodiments without in any way departing from the scope or spirit of the present invention as defined in the appended claims.