Patent Publication Number: US-8123574-B2

Title: Contact having increased resilience for use with electrical connector

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a contact for an electrical connector, and more particularly to such a contact with increased elasticity to provide a desired resilient compliance for electrically connecting an IC package and a printed circuit board. 
     2. Description of Prior Art 
     With the trend of miniaturization in computer technology, the electrical connectors with an insulating housing and a plurality of terminals becomes smaller and smaller. Due to their miniaturized dimension, the terminals, especially mating beams of the terminals are easily damaged because of stress overly exerted thereon when the terminals engage with pins of a complementary electronic package, such as an IC package. Several measurements are proposed to solve this problem. For example, as that disclosed in U.S. Pat. No. 6,929,483 issued to Huang on Aug. 16, 2005, and U.S. Pat. No. 6,695,624 issued to Szu on Feb. 24, 2004, is to modify the configuration of the terminals so as to obtain optimal electrical and mechanical performance of the mating beams of the terminals. 
     As disclosed in U.S. Pat. No. 6,695,624 issued to Szu on Feb. 24, 2004, an electrical connector is used for electrically connecting an IC package and a printed circuit board. The electrical connector includes a base defining a surface and a number of passageways, and a number of contacts. Each contact comprises an engaging portion for engaging with the passageway, a medial portion extending upwardly from an end of the engaging portion, a solder portion extending perpendicularly from an opposite end of the engaging portion, an inclined portion extending aslant from the medial portion, and a cantilever extending from the inclined portion. The inclined portion and the medial portion form a connecting portion having a first line therebetween. The first line forms an angle relative to the surface of the base. The inclined portion and the cantilever portion form another connecting portion therebetween having a second line, the second line forming another angle relative to the surface of the base. A contact portion is defined on an upper end of the cantilever. Thus, the length of the mating arm is long enough to be deformable and compliance to touch a pad of the IC package mounted on the electrical connector in order to ensure reliable electrical connection between the electrical connector and the IC package. However, the contact portions of the contacts are easy to slide out the pads of the IC package because of overly exerted stress when the IC package is mounted on the electrical connector. If that happens, the electrical connector can not work normally. 
     Hence, an improved contact for an electrical connector is required to overcome the disadvantages of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a contact for an electrical connector, wherein the contact has an increased elasticity to provide a good performance for electrically connecting an IC package and a printed circuit board. 
     To fulfill the above-mentioned object, a contact adapted for electrically connecting with an IC package and a printed circuit board, comprises a base portion adapted for being retained to an insulating housing, a solder portion extending from a lower end of the base portion and a turned portion bent downwardly from one end of the base portion. The solder portion is adapted for soldering the contact to the printed circuit board. The contact further includes a resilient arm extending upwardly from a bottom end of the turned portion. The resilient arm has an inclined portion and a cantilever beam. The inclined portion is connecting with the turned portion. The cantilever extends upwardly from a top end of the inclined portion and toward the turned portion to lengthen the resilient arm of the contact. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an assembled, perspective view of an electrical connector in accordance with a preferred embodiment of present invention; 
         FIG. 2  is an exploded, perspective view of the electrical connector shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of a contact of the electrical connector in accordance with the preferred embodiment of present invention; 
         FIG. 4  is a side view of the contact after being assembled in an insulative housing, but the insulative housing is not shown; 
         FIG. 5  is a perspective view of the insulative housing of the electrical connector in accordance with the preferred embodiment of present invention; 
         FIG. 6  is a cross-sectional view of the electrical connector of  FIG. 1  taken along line VI-VI of  FIG. 1 ; and 
         FIG. 7  is a perspective view of the electrical connector, showing the contact before being assembled in the insulative housing and the electrical connector electrically connecting an IC package and a printed circuit board. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the drawings to describe the present invention in detail. 
     Referring to  FIGS. 1 to 7 , there shows a perspective view of an electrical connector  1  used for electrically connecting an IC package  3  with a printed circuit board  4  incorporating inventive features of the present invention. The electrical connector  1  includes an insulative housing  10  and a plurality of contacts  20  received in the insulative housing  10 . 
     As shown in  FIGS. 2 and 3 , the contact  20  includes a plate-like base portion  201 , a pair of projecting portions  202  provided continuously at one end of the base portion  201  to extend in a direction substantially same as the base portion  201 , a turned portion  205  provided continuously at the end of the base portion  201  and bent downwardly to face the base portion  201 . The turned portion  205  is located between the pair of projecting portions  202  and extends downwardly aligned with a bottom end of the base portion  201 . The turned portion  205  faces against to the base portion  201 . The base portion  201  forms a plurality of barbs  204  at opposite sides thereof for retaining the terminal  20  to the insulting housing  10  of the electrical connector  1 . A solder portion  203  extends perpendicularly from an opposite end of the base portion  201 . The solder portion  203  can connect with a solder ball  5  for soldering the contact  20  on a pad  40  of the printed circuit  4 . 
     A resilient arm  206  extends upwardly from a bottom end of the turned portion  205  of the contact  20 . The resilient arm  206  includes an inclined portion  2061  connecting with the turned portion  205  and a cantilever beam  2062  extending upwardly from a top end of the inclined portion  2061 . An acute angle α is formed between the inclined portion  2061  of the resilient arm  206  and the turned portion  205 . The cantilever beam  2062  extends toward the projecting portions  202 . The inclined portion  2061  is approximately in a tapered shape and is tapered off from its lower end to its upper end. The cantilever beam  2062  is narrower than the inclined portion  2061  so as to increase an elasticity of the whole resilient arm  206 . An arc contact portion  2063  is formed on an upper end of the cantilever beam  2062  to conductively contact a corresponding conductive point  30  formed on the IC package  3  when the IC package  3  presses the arc contact portion  2063  downwardly. 
     The insulative housing  10  has a substantially rectangular shape, and includes a base  101  defining a mating surface  102  and a mounting surface  103 . A plurality through slots  104  extend between the mating surface  102  and the mounting surface  103  of the base  101 . The through slot  104  includes a first hole  1041  and a second hole  1041  connecting with the first hole  1041 . A length of the first hole  1041  at a longitudinal direction is L 1 , a length of the second hole  1042  at the longitudinal direction is L 3 , and L 3  is longer than the L 1 . The first hole  1041  is used to receive the base portion  201  of the contact  20 . A plurality of protrusions  1043  extend from inner walls of the first holes  1041  for engaging with the barbs  204  of the contacts  20  so as to retain the contact  20  in the through slots  104  of the insulative housing  10 . A length of the second hole  1042  at a transverse direction is L 2 , the biggest distance between the inclined portion  2061  and the turned portion  205  is L, and L 2  is shorter than L. 
     Referring to  FIG. 7 , when the contact  20  is received in the through slot  104  of the insulative housing  10 , the base  201  is retained in the first hole  2041  with the barbs  204 , and the resilient arm  206  abuts against inner wall of the second hole  1042 . And the cantilever beam  2062  of the contact  20  moves a certain distance closer to the turned portion  205  because of limitation of the inner wall of the slot  104 . When the IC package  3  is not mounted on the electrical connector  1 , the inclined portion  2061  is substantially parallel to the turned portion  205  and forms a U shape together with the turned portion  205 . But when the IC package  3  is driven downwardly by external force to press the contact  20 , the cantilever beam  2062  further continues to deflect downwardly. Thus, the contact portion  2063  can electrically connect with the conductive point  30  of the IC package  3 . 
     The contact  20  has the turned portion  205  extending downwardly from a top edge of the base portion  201  and the resilient arm  206  extending from a bottom edge of the turned portion  205  so that the resilient arm  206  of the contact  20  of the electrical connector  1  has an adequate length, and the cantilever beam  2062  can elastically touch with the IC package  3 . Thus, it can ensure a reliable electrical connection between the IC package  3  and the printed circuit board  4 . Additionally, when the contact  20  is received in the through slot  104  of the insulative housing  10 , the resilient arm  206  can be pre-loaded by the inner wall of the through slot  204 , the cantilever beam  2062  of the resilient arm  206  can deflect downwardly a certain distance and a height of the contact  20  become lower. So it can satisfy the miniaturized trend of the electrical connector  1 . Finally, the cantilever beam  2062  of the contact  20  can be pre-loaded by the inner walls of the through slot  104 . Thus it can avoid a wiping appearance caused by the contact portion  2063  of the contact  20  sliding excessively when the contact portion  2063  touches with the IC package  3 . From an overview point, the preferable embodiment of the instant invention essentially discloses a contact having the solder tail section ( 203 ) exposed below the bottom face of the housing, a contacting section ( 2062 ,  2063 ) upwardly extending above the upper face of the housing, and a serpentine connection section ( 201 ,  205 ,  2061 ) linked between the tail section ( 203 ) and the contacting section ( 2062 ,  2063 ) and located in the slot ( 104 ) and compressible in a transverse direction wherein two outermost segments of said serpentine connection section ( 201 ,  205 ,  2062 ) abut against the housing in an upstanding manner. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.