Abstract:
Disclosed is a socket connector ( 1 ) for testing IC chips. The socket connector includes a base ( 10 ), a plate ( 20 ) moveably mounted on the base ( 10 ) and a cover ( 30 ) located above the plate. A pair of actuators ( 60 ) is respectively engaged with the base, the plate and the cover to transform a vertical movement of the cover relative to the base to a horizontal movement of the plate relative to the base. A first and a second auxiliary plate ( 80, 82 ) are engageably attached to the base and the cover, respectively. A number of springs is disposed between and engaged with the auxiliary plates so as to avoid distortion of the cover.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to socket connectors, especially to a socket connector with anti-distortion functions used for testing Integrated Circuit chips (hereinafter simple for IC chip). 
   2. Description of Related Art 
   A socket connector is widely used for IC chip test. A conventional socket connector comprises a base, a movable plate mounted on the base and a plurality of actuators for actuating the movable plate to move relative to the base. The movable plate is movable between a rest position and an operating position. Such socket connectors are disclosed in U.S. Pat. No. 5,186,642 and No. 5,690,281. 
   Referring to  FIG. 3 , a conventional socket connector  9  used for IC chip tests comprises a squared flat base  90 , a movable plate  91  mounted on the base  90  and movable relative to the base  90 , a cover  92 , a plurality of springs  96 , an auxiliary member  93  and a pair of actuators  95 . 
   The movable plate  91  is a squared plan plate with a squared central portion cut away. The movable plate  91  comprises a plurality of first receiving holes  911  arranged in lines around the squared central portion for receiving pins of the IC chip. A pair of guiding portions  914  is formed at corner portions of a rear side of the movable plate  91 . Each guiding portion  914  defines a first engaging hole  916 . 
   The base  90  is a flat and plan plate, and defines a squared cutout at a central portion corresponding to the squared central portion of the movable plate  91 . A plurality of second receiving holes  901  is defined through the base  90  corresponding to the first receiving holes  911 . A pair of placing portions  903  is formed at opposite lateral sides adjacent to the front side. Four third receiving boles  9012  are defined at corner portions of the base  90 . 
   The cover  92  is a frame and defines an opening  921  at a central portion thereof, thus the first receiving holes  911  of the movable plate  91  are upwardly exposed. A plurality of forth receiving holes (not shown) corresponding to the third receiving holes  9012  of the base  90  is defined on a lower surface of corner portions of the cover  92 . A pair of positioning holes  924  is defines at each lateral side of the cover  92 . 
   In assembly, the movable plate  91  are mounted on the base  90 , with the first receiving holes  901  corresponding to the second receiving holes  911 . The auxiliary member  93  is fixed with the cover  92  through fastening with the positioning holes  924 . The actuators  95  are assembled with the corresponding auxiliary member  93  and respectively engaged with the first engaging hole  916  of the movable plate  91  and the placing portion  903  of the base  90 . Four springs  96  are received in the third receiving holes  9012  and the forth receiving holes. In operation, an external force is exerted on the cover  92  end the cover  92  is pressed downwardly. The movable plate  91  is actuated from the rest position to the operating position. Because of reserve forces of the springs  96  exerted on corner portions of the cover  92 , the cover  92  is easily distorted, which may lead to unreliable contact of the IC chip and the movable plate  91 . 
   Hence, an improved socket 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 new socket connector capable of avoiding distortions of a cover thereof. 
   A socket connector for testing IC chips includes a base, a plate moveably mounted on the base and a cover located above the plate. A pair of actuators is respectively engaged with the base, the plate and the cover to transform a vertical movement of the cover relative to the base to a horizontal movement of the plate relative to the base. A first and a second auxiliary plate are engageably attached to the base and the cover, respectively. A number of springs is disposed between and engaged with the auxiliary plates. 
   While an external force is exerted on the second auxiliary plate, the springs between the first auxiliary plate and the second auxiliary plate are resiliently distorted. There&#39;s not any reverse force of the springs exerted on the cover, thus, the cover may avoid a distortion. 
   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 and perspective view of a socket connector in accordance with a preferred embodiment of the present invention. 
       FIG. 2  is an assembled view of the socket connector of  FIG. 1 ; and 
       FIG. 3  is an exploded and perspective view of a conventional socket connector. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1 and 2 , a socket connector  1  in accordance with a preferred embodiment of the present invention is used for electrically interconnecting an IC chip (not shown) and a PCB (not shown). The socket connector  1  comprises a base  10 , a movable plate  20  mounted on the base  10  and moveable relative to the base  10 , a cover  30  mounted on the movable plate  20 , a plurality of springs  40 , a pair of auxiliary members  50 , a pair of actuators  60  for actuating the movable plate  20  to move in a horizontal directions and a pair of auxiliary plates  80 ,  82 . 
   The movable plate  20  is a squared plan plate with a squared central portion cut away. The movable plate  20  comprises a plurality of first receiving holes  201  arranged in lines around the squared central portion for receiving pins (not shown) of the IC chip therein. A pair of guiding portions  204  is formed at corner portions of a rear side of the movable plate  20 . Each guiding portion  204  defines a first engaging hole  206 . A plurality of locking portions  202  is formed at opposite lateral sides of the movable plate  20 . A tab  2020  laterally extends from a lower end of one locking portion  202 . 
   The base  10  has a flat and rectangular configuration, and defines a squared cutout corresponding to the squared central portion of the movable plate  20  at a central portion thereof. A plurality of second receiving hales  101  corresponding to the first receiving holes  201  is defined in the base  10 . A pair of placing portions  103  is formed at opposite lateral sides of the base  10 . Each placing portion  103  defines a first engaging trough  1020 . A pair of lengthwise slits  1014  is symmetrically defined on the base  10 . A pair of positioning portions  102  is respectively formed at lateral sides of the base  10 . A projection  106  upwardly projects from each positioning portion  102 . Four clasping portions  104  respectively and upwardly project from corner portions of the positioning portions  102  and the placing portions  103 . Each clasping portion  104  forms a clasping end  1040  at a free end thereof. 
   The cover  30  defines an opening  301  at a central portion thereof, thus the movable plate  20  are upwardly exposed. A pair of first positioning holes  304  is defined at each lateral sides of the cover  30 . A pair of recesses  306  corresponding to the projections  106  of the base  10  is defined at two lateral sides of the cover  30 . The cover  30  also defines a plurality of second engaging troughs  302  corresponding to the clasping portions  104  of the base  10 . A pair of engaging tabs  307  respectively and horizontally extends from a front side and a rear side of the cover  30  in opposite directions. The engaging tabs  307  each defines a pair of second engaging holes  3071  therethrough. 
   The auxiliary member  50  comprises a horizontal portion  501  and a vertical portion  502  extending downwardly from the horizontal portion  501 . The horizontal portion  501  defines a pair of second positioning holes  503  corresponding to the first positioning holes  304 . The vertical portion  502  defines a positioning hollow  505  thererthrough. The actuators  60  are engaged with the auxiliary members  50 . The actuator  60  includes a first operating arm  601  and a second operating arm  602 . The first operating arm  601  defines a first operating hollow  6010 . The second operating arm  602  defines a second operating hollow  6020 . A first bolt  70  bolts through the first operating hollow  6010 , the second operating hollow  6020  and the positioning hollow  505 , thereby securing the actuator  60  with the auxiliary member  50  and ensuring pivotal movements of the actuator  60 . The first operating arm  601  has a first pole  603  laterally extending from a free end in a same direction as the horizontal portion  501  extends. The second operating arm  602  has a second pole  604  extending from a free end in a same direction as the first pole  603  extends. 
   The auxiliary plates comprise a first auxiliary plate  82  and a second auxiliary plate  80 . The auxiliary plates substantially are squared frames. The first auxiliary plate  82  comprises a plurality of third positioning holes  822  defined through middle portions of opposite sides thereof. Four third receiving holes  828  are defined at corner portions of the first auxiliary plate to receive the springs  40 . The second auxiliary plate  80  comprises a plurality of third engaging holes  802  corresponding to the second engaging holes  3071  defined on the engaging tabs  307 . Four forth receiving holes (not shown) is defined at lower surface of the second auxiliary plate  80 . 
   In assembly, the first auxiliary plate  82  is fixed by bolting the third positioning holes  822  with the PCB. The base  10  is mounted on the PCB and engaged with the first auxiliary plate  82 . The movable plate  20  is mounted on the base  10 . The locking portions  202  of the movable plate  20  is inserted through the slits  1014  and locked with the PCB. As the slits  1014  are wider than the locking portion  202  in longitudinal direction, the slits  1014  are able to guide longitudinal movements of the movable plate  20 . The actuators  60  are respectively engaged with the auxiliary members  50 . The first bolt  70  respectively bolts through the first operating hollow  6010  of the first operating arm  601 , the second operating hollow  6020  of the second operating arm  602  and the positioning hollow  505  of the auxiliary member  501 , thereby securing the actuator  60  with the auxiliary member  50  and ensuring pivotal movements of the actuator  60 . The first poles  603  of the first operating arms  601  are engaged with the first engaging hole  206  of the movable plate  20 , and the second poles  604  are engaged with the first engaging trough  1020 . The auxiliary members  50  are secured with the cover  30  by bolting the first positioning holes  304  and the second positioning holes  503 . The clasping portions  104  are engaged with the second engaging trough  302 . The projections  106  are engaged with the recesses  306 . The second auxiliary plate  80  is mounted on the cover  30 . Second bolts  84  are inserted into the third engaging holes  802  and the second engaging holes  3071 , thereby fixing the second auxiliary plate  80  with the cover  30 . Each of the springs  40  is located between the first auxiliary plate  80  and the second auxiliary plate  82 , with one end thereof being received in the third receiving hole  828  and the other end thereof being received in the forth receiving hole. 
   In normal, the movable plate  20  is at the rest position. In operation, an external force is exerted on the cover  30  via the second auxiliary plate  80 . The cover  30  is pressed down which causes pivotal movements of the first operating arm  601  and the second operating arm  602  in opposite direction. Because the second operating arms  602  is engaged with base  10  which is fixed with the PCB, in the pivotal movements, the free ends of the first operating arms  601  move away and take the movable plate  20  to the operating position. When the external force is released, the cover  30  is raised under a reserve operating force of the springs  40 , and the first operating arm  601  and the second operating arm  602  move toward each other. Therefore, the movable plate  20  is taken to the rest position. 
   It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not be limited to the details given herein.