Abstract:
A socket connector ( 1 ) includes a base ( 2 ), a cover ( 3 ) slidably assembled onto the base and capable being moved with respect to the base along a front-to-rear direction, an actuator ( 5 ) for actuating the cover to slide on the base between a contact insert position and an engagement position, lock portion ( 406 ) and receiving arrangement ( 204 ) arranged between the base and the cover and opposite to the actuator in the front-to-rear direction so as to fasten the base and the cover tightly.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an electrical connector, and more particularly to a ZIF (Zero Insertion Force) socket connector for connecting a central processing unit (CPU) of a computer system to a printed circuit board (PCB). 
   2. Description of Related Art 
   With the development of technology, socket connectors, which have pins or solder balls, are found widespread applications in computers and other electrical devices for transmitting signals and conducting current between a printed circuit board (PCB) and an IC package. 
   Referring to  FIGS. 1–2 , a conventional socket connector  9  comprises a base  91 , a cover  93  slidably mounted on the base  91  and a lever  94  sandwiched between the base  91  and the cover  93 . The lever  94  includes a cam shaft  944  received in the base  91  and an operating handle  940  vertically extending from the cam shaft  944 . The base  91  defines a mating portion  910  with a plurality of passageways  914  vertically extending through a top and a bottom faces for receiving a plurality of terminals  92  therein, and a header portion  912  having a channel  911  extending along a lateral direction. A pair of protrusions  916  is formed on opposite side of the mating portion  910 . The cover  93  includes a mating portion  930  for mating with an IC package (not shown). The mating portion  930  defines a plurality of passageways  934  in alignment with the passageways  914  for allowing downwardly extending pins of an IC package (not show) to extend therthrough to engage with the terminals  92 . A pair of side walls downwardly extending from opposite ends of the mating portion  930  with a pair of slot  936  formed thereon. The cover  93  further includes a header portion  932  having a channel  931  extending along a lateral direction. A pair of locking barbs  938  are extending downwardly from the header portion  932  adjacent to the channel  931  alignment with corresponding portion of the base  91 . 
   In assembly, the cover  93  movably mounted on the base  91 , the terminals  92  is received in the passageways  914  of the base  91  and the lever  94  is sandwiched between the base  91  and the cover  93 . The cover  93  can slide on the base  91  by actuating the lever  94  from a vertical position to a horizontal position, which makes pins of the IC package move simultaneously for establishing/disestablishing an electrical connection between the pins of the IC package and mating portions of the terminals  92 . It is noted the steady electrical connection between the IC package and the PCB is deeply affected by the plainness between the cover and the base. 
   As the base  91  and the cover  93  is conventionally made from insulative materials by molded, and they should be made thin enough, they are apt to warp in molding or cooling process. When the warped base or cover are assembled, the header portions of the socket are fastened tightly enough by the engagement of the barbs  938  with the base, and the mating portions also can be engaged tightly by the engagement of the protrusions  916  with the slots  936 . But the warp of the socket will make a rear portion of the socket to form an aperture, and make the contacts  92  in the rear portion touch dust out of the socket. Furthermore the warp of the socket make the passageways  934  can not alignment with the passageways  914  respectively, and the terminal  92  cannot contact the pins of the IC package steadily. 
   To overcome above-motioned problems, an improved socket connector is desired. 
   SUMMARY OF THE INVENTION 
   An object of the present invention, therefore, is to provide a socket connector with lock portion for preventing a plane thereof from warping. 
   Accordingly, to achieve the above object, a socket connector includes a base, a cover slidably assembled onto the base and capable being moved with respect to the base along a front-to-rear direction, an actuator for actuating the cover to slide on the base between a contact insert position and an engagement position, lock portion and receiving arrangement arranged between the base and the cover and opposite to the actuator in the front-to-rear direction so as to fasten the base and the cover tightly 
   Other objects, advantages and novel features of the present 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 exploded view of a conventional socket connector; 
       FIG. 2  is an assembled perspective view of the socket connector of  FIG. 1 ; 
       FIG. 3  is an exploded view from a top aspect of the socket connector in accordance with an embodiment of the present invention; and 
       FIG. 4  is an assembled perspective view of the socket connector of  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made to the drawing figures to describe the present invention in detail. 
   Referring to  FIGS. 3 , a socket connector  1  in accordance with an embodiment of the present invention is used for connecting a chip module (not shown) to a printed circuit board (PCB, not shown) and comprises an insulative base  2 , a cover  4  slidably engaged on the base  2  in a front-to-rear direction, a plurality of contacts (not shown) received in the base  2  and contacting with the PCB and an actuator  5 . 
   The base  2  comprises an insulative main body  20  in the shape of a square, an insulative front portion  22  in front of the main body  20 . The main body  20  defines a plurality of passageways  200  extending vertically through the main body  20 . Each passageway  20  receives a contact (not shown) therein. A pair of protrusions  202  extend from each side edge of the main body  20 , and a pair of T-shaped recesses  204  form on a rear edge of the main body  20 , each having a pair of protrusions  206  extending face to face respectively. The front portion  22  comprises an upper surface (not labeled) for mating with the cover  4  and a bottom surface (not labeled) for mating with the printed circuit board. A base through hole  220  forms on the front portion  22  for engaging with the actuator  5 . A pair of blocks  222  upwardly protrude from the upper surface of the front portion  22  and are respectively arranged on opposite lateral sides of the base through hole  220 . A pair of recesses  224  are formed on opposite inner faces of blocks  222 . 
   The cover  4  comprises an insulative body portion  40  in the shape of a square, an insulative header portion  42  in front of the body portion  40 . The body portion  40  defines receiving portion  400  with a plurality of channels  404  provided in a one-to-one corresponding relationship with the passageways  200  of the underlying base  2 , and comprises a pair of lateral flanges  402  depending down vertically on two sides thereof. Each flange  402  defines a pair of fixing slots in an inner wall thereof for receiving corresponding protrusions  202 , respectively, each leaving a small distance for the protrusions  202  to slide therein along a lengthwise direction. A pair of T-shaped lock portions  406  form on a rear portion of the body portion  40  depending down vertically with a pair of protrusions  408  extending from two sides respectively. The header portion  42  defines a rectangular cover through hole  420 . 
   The actuator  5  in present invention is in form of cam which comprising a cam  51 , a metallic top cover plate  52 , a metallic bottom cover plate  53 , a base plate  54  and a washer  55 . 
   The metallic top cover plate  52  comprises a first central hole  522  corresponding to the base through hole  220 , a pair of ear portions  520  extending from two sides respectively, and a pair of stoppers  524  are formed on opposite sides of the first central hole  522  of the top cover plate  52  to stop the cam  51 . 
   The metallic bottom cover plate  53  is in form of “I” type with an opening  530  is formed in a central portion. The bottom cover plate  53  is insert-molded on a bottom of the header portion  42  of the cover  4  for enhancing intension of it. 
   The base plate  54  is also in form of “I” type which smaller than the cover plate  53 , an opening  540  is formed in a central portion of the plate  54  which has a diameter equal to the through hole  220  of the base  2 . The base plate  54  is insert-molded on a bottom of front portion  22  for enhancing intension of it. 
   The cam  51  successively comprises a first, a second, a third, a fourth cylindrical posts  510 ,  512 ,  514 ,  516  and a fifth post (not shown) formed one on the other. The cylindrical posts progressively decrease in diameter from top to bottom. A diameter of the first post  510  is bigger than that of the central hole  522 , and a slot  518  is formed on an up surface of the post  510  and a protrusion  519  extends from a circumferential periphery thereof. The second post  512 , the third post  514 , the fourth post  516  and the fifth post are respectively received in the central hole  522 , the cover through hole  420 , the second central hole  540  and an opening  550  on the washer  55 . Central axes of the first, the second, the fourth cylindrical posts  510 ,  512 ,  516  and the fifth cylindrical post are in-line, but the third cylindrical post  514  is offset, which forms an eccentricity design. 
   In assembly, the cover  4  is assembled onto the base  2  with the protrusions  202  of the base  2  engaging with the fixing slots of the cover  4 . The header portion  42  is pressed onto the front portion  22  between two blocks  222 . The lock portions  406  is placed out of the recesses  204 , and engaged on the recesses  204  by moving the cover  4  with protrusions  408  engaging with the protrusions  206  to make the rear portions of the base and the cover engaged together tightly. Each protrusion  202  is received into a fixing slot on the flange  402  to make the side portion of the base and the cover engaged together tightly. The top cover plate  52  is pressed on the cover  4  with ear portions  520  received in the recesses  224  respectively. Successively, the cam  51  is mounted into the socket connector  1  from the top via the central hole  522  and then through the through holes  420 ,  220  and openings  530 ,  540 . The fifth post of the cam  51  extends through the hole  540  of the bottom plate  54  and the riveting end thereof is riveted with the washer  55  attached on a lower surface of the base  2 , whereby the cam  51 , the cover  4 , the base  2 , and the washer  55  are assembled together. 
   A tool can be fitted into the groove  518  of the cam  51  to rotate the cam  51  until the protrusion  519  abuts against the cam stopper  524  of the cover plate  52 . Since the axis of the cam block  43  is offset from the axis of the post  510 , the rotation of the cam  51  forces the cover  4  to slide along the base  2  in a front-to-rear direction, thereby making the pins (not shown) of the CPU passing through the channels  404  and extending into the passageways formed on the base  2  with zero insert force (ZIF). To making the pins of CPU engage with the terminals of the socket, the cam actuator  40  is rotated in an opposite direction from one of the two cam stoppers  524 , to the other cam stopper  524 , thereby the pins of the CPU is engaged with the terminals of the socket  1  and allowing the CPU to electrically connect with the PCB. 
   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.