Patent Publication Number: US-6984142-B2

Title: Socket for electrical parts

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a socket for an electrical part for testing or inspecting a performance of an electrical part such as semiconductor device, which will be called hereinlater “IC package”. 
   2. Related Art 
   There is known an IC socket, as such a socket for electrical part, for accommodating an IC package as an electrical part, for example, as disclosed in the Japanese Laid-open Patent Publication No. JP H11-26126-A. 
   In this known example, the IC package is provided with a number of solder balls, as terminals, projecting downward from the lower surface of the IC package so as to provide a grid (lattice) arrangement having vertical and horizontal rows or lines. 
   On the other hand, the IC socket comprises a socket body to which the IC package is mounted and accommodated, a number of contact pins arranged to the socket body to be contacted to the terminal of the IC package, a movable member movably provided for the socket body to elastically deform the contacts pins so as to be contacted to or separated from the terminals of the IC package, and a cover for moving the movable member by means of lever member. 
   In an operation, when the cover is moved downward, a force applied portion of the lever member is depressed and is rotated about a shaft penetrating the movable member, so that the socket body is pressed downward by a force support (fulcrum) portion on the lower end side of the lever member. Therefore, the shaft acts as force applying (functioning) portion and moves parallelly horizontally in one direction to thereby move the movable member. 
   According to the movement of the movable member, the contact pins are pressed and elastically deformed to thereby open a pair of contact portions of each contact pin and then to insert the solder ball of the IC package into a gap between the opened contact a portions. 
   On the contrary, when the cover is moved upward, the pressing force of the movable member applied on the contact pins is released, and the contact portions of each of the contact pins return toward their initial closed positions to thereby clamp the solder ball therebetween and establish an electrical connection therebetween. 
   In the conventional structure mentioned above, however, the shaft (as force applying portion) of the lever member is provided so as to penetrate one end side of the movable member, i.e., the rear end side portion in the moving direction at the opening of the contact portions of the contact pin, so that when the pressing force is applied to the movable member through this shaft, the force applying direction of this pressing force is not necessarily horizontal with respect to the movable member. Accordingly, in the case where such pressing force is applied to the end portion of the movable member, the other end portion thereof maybe lifted, i.e., floated, which may lead to a trouble of an unstable attitude of the movable member, thus being inconvenient. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is therefore to substantially eliminate defects or inconveniences encountered in the prior art mentioned above and to provide a socket for an electrical part capable of providing structure in which the movable member of the socket body can maintain its stable attitude at the time of being pressed and moved to elastically deform the contact pins arranged to the socket body. 
   This and other objects can be achieved according to the present invention by providing a socket for an electrical part comprising: a socket body to which an electrical part is mounted and accommodated; a number of contact pins provided for the socket body so as to be contacted to or separated from the terminals of the electrical part, each of the contact pins being provided with a pair of contact portions between which the terminal is inserted; a movable member provided for the socket body to be movable so as to deform the contact portions of the contact pin; and a driving mechanism provided for the socket body to move the movable member, wherein the driving mechanism has a force applying portion through which a force is applied to the movable member to move it and the force applying portion is disposed at substantially a central portion on a side portion of the movable member along the movable member moving direction. 
   In a preferred embodiment or example in the above aspect, the movable member may be composed of a plate member having substantially a square shape to be moved in one diagonal direction thereof with respect to the socket body, and the force applying portion of the driving mechanism is disposed to a portion near a corner portion of the movable member along another diagonal line normal to the moving direction of the movable member. 
   The movable member may be provided, at a rear end side in a moving direction thereof, with a deformation prevention member for preventing the movable member from being deformed at a time of elastically deforming the contact pin. 
   The force applying portion of the driving mechanism is coupled to the deformation prevention member. The driving mechanism is provided with lever members, each of the lever members being pivotal in a vertical direction with respect to the movable member and being formed with a force applied portion to which an external force is applied, a force support portion coupled to the socket body and the force applying portion coupled to the movable member, and when the force applied portion of the lever member is pressed, the lever member is rotated around the force support portion and the movable member is thereby moved by the force applying portion. 
   The driving mechanism includes a further lever member provided for the movable member at a corner portion thereof along the one diagonal line in the movable member moving direction, and this further lever member is provided with a force applied portion and a support portion operatively connected to the movable member. 
   In a more specified aspect of the present invention, the above-mentioned object of the present invention may be achieved by providing a socket for an electrical part, which comprises: a socket body to which an electrical part is mounted and accommodated; a number of contact pins provided for the socket body so as to be contacted to or separated from the terminals of the electrical part, each of the contact pins being provided with a pair of contact portions; a slide plate provided for the socket body to be movable to thereby deform the contact portions of the contact pin, the slide plate having substantially square plate shape; a driving mechanism provided for the socket body so as to move the slide plate, the driving mechanism including an operation member mounted to the socket body to be vertically movable; and a deformation prevention member for preventing deformation of the slide plate at a time when the contact pin is elastically deformed, wherein the driving mechanism includes a pair of lever members disposed to the portions near the corner portions of the slide plate along a diagonal line normal to the moving direction of the slide plate and connected to the operation member to be applied with a pressed force when the operation member is pressed downward, and the deformation prevention member has both ends to each of which a pair of support pieces are formed between which each of the lever members are clamped and supported. 
   According to the present invention of the structures and characters mentioned above, since the force applying portion of the driving mechanism for moving the movable member is disposed at substantially the central portion of the movable member in the moving direction, external force is applied to the movable member at this central portion, not on the end portions thereof as in the conventional structure, the movable member can be moved with the stable attitude thereof being maintained. 
   In the structure of the movable member having substantially a square plate shape, the force applying portions are disposed at portions near the corner portions on the diagonal line normal to the moving direction of the movable member, so that the stable moving of the movable member by the driving mechanism can be ensured. 
   The arrangement of the deformation prevention member can positively prevent the movable member from being adversely deformed. Moreover, since the force applying portion of the driving mechanism is coupled to the deformation prevention member, through which the movable member is moved, the force is applied in a dispersed fashion and not concentrated, thus also ensuring the stable attitude of the movable member during its moving operation. 
   Furthermore, the lever member as the driving mechanism is provided with the force applied portion to which an external force is applied, the force support portion connected to the socket body as fulcrum portion and the force applying portion connected to the movable member, which is then moved when the force applied portion is pressed, the movable member is moved through the force support portion and the force applying portion of the lever member. Thus, the movable member can be stably moved with simple and compact structure. 
   The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
       FIG. 1  is a plan view of an IC socket according to a first embodiment of the present invention; 
       FIG. 2  is a sectional view taken along the line II—II in  FIG. 1 ; 
       FIG. 3  is a sectional view taken along the line III—III in  FIG. 1 ; 
       FIG. 4  is a perspective view of the IC socket of  FIG. 1  in a state that an operation member of the socket is positioned at an uppermost position; 
       FIG. 5  is a perspective view of the IC socket of  FIG. 1  in a state that an operation member of the socket is positioned at a lowermost position; 
       FIG. 6  is a developed perspective view of the IC socket of the first embodiment; 
       FIG. 7  shows a perspective view of a socket body of the IC socket of this first embodiment from which the operation member, a guide member and like are removed; 
       FIG. 8  is a perspective view of the socket body into which a slide plate, as movable member, is assembled; 
       FIG. 9  is a perspective view of the socket body into which a support plate and associated parts are assembled; 
       FIG. 10  is a perspective view of the socket body into which the guide member and a latch are assembled; 
       FIG. 11  is a plan view of the slide plate of the IC socket of the first embodiment; 
       FIG. 12  is a side view of the slide plate viewed from a direction of an arrow A in  FIG. 11 ; 
       FIG. 13  is a plan view of the support plate of the IC socket of the first embodiment; 
       FIG. 14  is a front view of the support plate of  FIG. 13 ; 
       FIG. 15  is a right-side view of the support plate of  FIG. 13 ; 
       FIG. 16  is a front view of the support plate of the IC socket of the first embodiment; 
       FIG. 17  is a bottom view of the IC socket of the first embodiment; 
       FIG. 18  is a right-side view of the IC socket of the first embodiment; 
       FIG. 19  is a perspective view, in an enlarged scale, showing a lever member of the IC socket of the first embodiment in a state before its pivotal rotation in the downward direction; 
       FIG. 20  is also a perspective view similar to that of  FIG. 19  in a state that the lever member is rotated downward; 
       FIG. 21  is also a perspective view similar to that of  FIG. 20  in a state that the lever member is further rotated downward from the state of  FIG. 20 ; 
       FIG. 22  is also a perspective view similar to that of  FIG. 20  in a state that the lever member is further rotated to the most downward position from the state of  FIG. 21 ; 
       FIG. 23  includes  FIG. 23A  showing a contact pin of the closed state and  FIG. 23B  showing a contact pin of the opened state; 
       FIG. 24  represents an IC package for the IC socket of the first embodiment and includes  FIG. 24A  showing a front view thereof and  FIG. 24B  showing a bottom view thereof; 
       FIG. 25  is a perspective view of an IC socket according to a second embodiment of the present invention showing a slide plate, a first link, a second link, a support plate and so on of the IC socket; 
       FIG. 26  is a perspective view showing the IC socket of the second embodiment showing a state of the first and second links before the downward rotation thereof; 
       FIG. 27  is a perspective view showing the IC socket of the second embodiment showing a state that the first and second links are pivotally rotated downward from the state shown in  FIG. 26 ; 
       FIG. 28  is also a perspective view showing the IC socket of the second embodiment showing the lowermost state of the first and second links; and 
       FIG. 29  is an illustrated plan view of a modified example of the IC socket of the first embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The preferred embodiments of the present invention will be described hereunder with reference to the accompanying drawings. Further, it is to be noted that terms of “upper (upward)”, “lower (downward)”, “left”, “right” and like terms are used herein with reference to the illustrations of the accompanying drawings or in a state that a socket body is placed horizontally. 
   [First Embodiment] 
   The first embodiment of the present invention is first described hereunder with reference to  FIG. 1  to  FIG. 24 . 
   Reference numeral  11  denotes an IC socket as a socket for an electrical part, and the IC socket  11  is a socket to be arranged on a printed circuit board, not shown. An IC package  12  as an electrical part is supported or mounted to the IC socket  11  to thereby establish an electrical connection between the IC package  12  and the printed circuit board. 
   The IC package  12  has a structure of so-called BGA (Ball Grid Array) type such as shown in  FIGS. 24A and 24B , which, for example, includes a square-shaped package body  12   a  having a lower surface from which a number of spherical solder balls  12   b  as terminals project in a matrix arrangement. 
   On the other hand, as shown in  FIG. 2  or  6 , the IC socket  11  has a socket body  13  mounted to the printed circuit board, and a number of contact pins  15  are arranged to the socket body  13  so as to be contacted to or separated from the solder balls  12   a , respectively A slide plate  17  as a movable member and a guide member  18  are disposed to the upper side of the socket body  13 , and an adopter  20  and a location board  21  are also disposed to the lower side of the socket body  13 . 
   In addition, an operation member  23  is disposed further above the slide plate  17  and the guide member  18  for moving the slide plate  17  in the horizontal direction by means of lever member  22 , as a “driving mechanism”. 
   Each of the contact pins  15  is formed from a plate-like member having an elastic property, i.e., springy property and a good conductivity through a press-working. As shown in  FIGS. 23A and 23B , the contact pin  15  has a pair of elastic portions constituting a stationary side elastic piece  15   a  and a movable side elastic piece  15   b  at portions above, in the vertical direction, the middle portion of the contact pin  15 . The lower end portions of these elastic pieces  15   a  and  15   b  are formed as a single solder tail portion  15   c  as shown in  FIG. 2 , for example. 
   These elastic pieces  15   a  and  15   b  are arranged so as to oppose to each other and have front (tip) end portions formed as stationary contact portion  15   e  and movable contact portion  15   f , respectively, which are contacted to or separated from the side portion of the solder ball  12   b  of the IC package  12 , the solder ball  12   b  being then clamped between these contact portions  15   e  and  15   f.    
   The contact pins  15  are pressed into press-in holes formed to the socket body  13 , and the solder tail portions  15   c  projecting downward from the socket body  13  further extend downward through the location board  21  and then inserted into through holes formed to the printed circuit board and then soldered thereto. 
   The slide plate  17  has a rectangular plate shape as shown in  FIG. 11  or  12  and is arranged to be movable in its diagonal direction with respect to the socket body  13 . The slide plate  17  is formed with a number of insertion holes  17   a , in a grid arrangement, into which the elastic pieces  15   a  and  15   b  of the contact pins  15  are inserted. A portion between these insertion holes  17   a  is formed as pressing portion  17   b  such as shown in  FIG. 11 . 
   In operation, when the slide plate  17  is moved, the movable elastic piece  15   b  is pressed and is elastically deformed by the pressing portion  17   b , and the movable contact portion  15   f  is displaced in a predetermined amounts, as shown in  FIGS. 23A and 23B . 
   The slide plate  17  is provided with support plates  24  to the two sides  17   f ,  17   f  of a rear end side shown in  FIG. 7 , in the moving direction of the slide plate  17  for preventing a deformation of the slide plate  17  at the elastic deformation of the movable elastic piece  15   b  of the contact pin  15 , and accordingly, the support plate  24  may be called “deformation prevention member”. 
   Each of the support plates  24  is made of metal, and as shown in  FIGS. 13 to 15 , is bent so as to provide a right angle. Lever members  22 , as portions or parts of the “driving mechanism”, are provided for the end portions of the support plates  24 . That is, both the end portions  24   a  of the support plate  24  are positioned at corner portions  17   c  of the slide plate  17  in one diagonal line direction normal to the moving direction of the slide plate  17 . The end portions  24   a  are provided with a pair of support pieces  24   b  opposing to each other, between which the lever member  22  is arranged and clamped. 
   The lever member  22  has a shape shown in  FIGS. 16 to 18  and is supported by a pair of supporting pieces  24   b  to be rotatable (pivotal) by means of the rotation (pivot) shaft  25  being the “force applied portion” as shown in  FIGS. 9 and 19 . This rotation shaft  25  is arranged to substantially the central portion of the side portion of the slide plate  17  in the moving direction thereof. 
   Furthermore, the lever member  22  is provided, at its front end portion (one end portion), with the force applied portion  22   a  which is pressed by the operation member  23 , and at its rear end portion (other end portion), with the force support (fulcrum) portion  22   b  abutting against the pressing wall  13   b  of the socket body  13 . The force support portion  22   b  is located at the position where the lever member  22  abuts against the pressing wall  13   b , so that the force support portion  22   b  is slightly displaced in accordance with the pivotal rotation of the lever member  22 . 
   When the force applied portion  22   a  of the lever member  22  is depressed downward to thereby rotate the rotation shaft  25  around its center, the pressing wall  13   b  of the socket body  13  is pressed by the force support portion  22   b . Then, the rotation shaft  25  is moved by the reaction force from the pressing force, parallelly horizontally in the arrowed direction in  FIGS. 19  to  22 . Thus, the slide plate  17  is moved in the arrowed direction (diagonal direction) in  FIG. 7  through the support plate  24 . 
   Further, each of the lever members  22  is designed so that the force applied portion  22   a  takes a position approximately equal, in height level, to the rotation shaft  25  under a state that the lever member  22  is pressed downward to the fullest extent as shown in  FIG. 22 . 
   Moreover, another lever member  26  is disposed, as shown in  FIGS. 7 and 8 , to the front end corner side in the moving direction of the slide plate  17  when the operation member  23  is lowered. This lever member  26  has a shape or structure similar to that of the lever member  22 . That is, a pair of support pieces  17   d  are formed to the front end side of the slide plate  17  as shown in  FIG. 11  and the lever member  26  is inserted between these support pieces  17   d  to be rotatable by a rotation (pivot) shaft  27 . The lever member  26  is also provided with a force applied portion  26   a  pressed by the operation member  23  and a force support portion (fulcrum)  26   b  pressed toward the pressing wall  13   b  of the socket body  13 . 
   When the force applied portion  26   a  of the lever member  26  is pressed downward and then rotated about the rotation shaft  27 , the pressing wall  13   b  of the socket body  13  is pressed by the force support portion  26   b , and then, by the reaction force, the rotation shaft  27  is moved in a parallel direction. Therefore, the front end portion in the moving direction of the slide plate  17  is pulled and moved in the arrowed direction (diagonal direction) in  FIG. 7 . 
   On the other hand, as shown in  FIGS. 3 and 6 , the guide member  18  has a rectangular frame shape and is formed with a guide surface  18   a  inclined for guiding the IC package  12  to the predetermined position and also provided with a plurality of engaging claws  18   b  for engaging or locking the IC package  12  to the socket body  13 . 
   Furthermore, as shown in  FIGS. 1 to 3 , the operation member  23  has an opening  23   a  of a size allowing the IC package  12  to be inserted. After the IC package  12  is inserted through this opening  23   a , it is mounted and accommodated to the predetermined position on the accommodation surface portion  17   e  of the slide plate  17 . 
   Moreover, this operation member  23  is arranged to be vertically movable with respect to the socket body  13 , as shown in  FIG. 3 , and is urged upward by means of spring  29 . The operation member  23  is provided with a plurality of engaging claws  23   d , which are disposed to project downward, and these engaging claws  23   d  are engaged with the socket body  13  at the uppermost position of the operation member  23  to stop the operation member  23  there. In addition, the operation member  23  is formed with a first operation projection, not shown, for pressing the force applied portions  22   a  and  26   a  of the lever members  22  and  26  and a second operation projection  23   c  for rotating a latch  30  as shown in  FIG. 2 . 
   The latch  30  is mounted to the socket body  13  to be pivotal around a shaft  31 , as shown in  FIG. 2 , for example, and is urged towards the center direction of the socket body  13  by means of spring  32  so as to press the peripheral edge portion  12   c  of the IC package body  12   a  by a pressing portion  30   a  formed to the front end portion of the latch  30 . 
   The latch  30  is also formed with a portion to be pressed (pressed portion  30   b ) which is pressed by the second operation projection  23   c  of the operation member  23 . When the operation member  23  is lowered, the portion  30   b  is pressed by the second operation projection  23   c , the latch  30  is then rotated in the outward direction of the socket body  13  as shown with two-dot-chain line in  FIG. 2  and the pressing portion  30   a  of the latch  30  is retired from the IC package arranging position. 
   The socket for an electrical part, i.e., IC socket for the IC package according to the present invention of the structure mentioned above will operate as follows. 
   A printed circuit board on which a number of IC sockets  11  are arranged is previously prepared, and then, in order to set the IC packages  12  respectively to the IC sockets  11  by using an automatic machine, the operation member  23  is first pressed downward. 
   According to this lowering motion of the operation member  23 , the force applied portions  22   a  and  26   a  of the lever members  22  and  26  are pressed by the first operation projection, not shown, of the operation member  23 . Then, the lever members  22  and  26  are rotated, i.e., pivoted around the rotation shafts  25  and  27 , and the force support portions  22   b  and  26   b  press the pressing wall  13   b  of the socket body  13  while sliding thereon. In this moment, by the reaction force from the pressing wall  13   b , the respective rotation shafts  25  and  27  are moved horizontally in the arrowed direction in  FIG. 7 . 
   During the operation mentioned above, the lever members  22  operate in the following manner. 
   When the force applied portion  22   a  of each lever member  22  is pressed from the state shown in  FIG. 19 , the lever member  22  is rotated around the rotation shaft  25 , and the force support portion  22   b  presses the pressing wall  13   b  of the socket body  13  while sliding thereon as shown in  FIGS. 20 and 21 . In this moment, by the reaction force from the pressing wall  13   b , each of the respective rotation shafts  25  is moved horizontally in the arrowed direction in  FIG. 7 , and the lever members  22  rotated to the utmost downward position as shown in  FIG. 22 . 
   Then, when the rotation shafts  25  and  27  are moved horizontally, the slide plate  17  is moved. When the rotation shaft  25  is moved horizontally, the slide plate  17  is moved via the support plate  24 . 
   According to the movement of the slide plate  17  as mentioned above, the movable side elastic piece  15   b  of each of the contact pins  15  are pressed and elastically deformed by the pressing of the pressing portion  17   b  of the slide plate  17  from the state shown in  FIG. 23A  to the state shown in  FIG. 23B . Thus, the paired contact portions  15   e  and  15   f  of the contact pin  15  are opened. 
   During the above operation, the pressed portion  30   b  of the latch  30  is pressed by the second operation projection  23   c  of the operation member  23 , is rotated in the clockwise direction in  FIG. 2  against the urging force of the spring  32 , and the pressing portion  30   a  is then displaced to the retired position shown with two-dot-chain line in  FIG. 2 . 
   Under the state mentioned above, the IC package  12  conveyed by the automatic machine is accommodated onto the accommodation surface portion  17   e  of the slide plate  17  and then guided to the predetermined position by means of guide member  18   a . At this position, the respective solder balls  12   b  of the IC package  12  are inserted into the insertion openings  17   a  of the slide plate  17  in the state of projecting downward over the slide plate  17  and inserted, in the non-contact state, into the paired contact portions  15   e  and  15   f  of the respective contact pins  15 . 
   Thereafter, when the downward pressing force to the operation member  23  is released, the operation member  23  is moved upward by the urging force of the spring  29 , and thereby, the pressing force applied to the lever members  22  and  26  are also released. Thus, the slide plate  17  is moved, in a direction reverse to the arrowed direction in  FIG. 7 , by the elastic force (elasticity) of the movable side elastic piece  15   b  of the contact pin  15 . 
   At this time, the pressing force to the latch  30  applied by the operation member  23  is also released, the latch  30  is rotated in the counter-clockwise direction in  FIG. 2  by the urging force of the spring  32 , and the peripheral edge portion  12   c  of the IC package  12  is pressed by the pressing portion  30   a  of the latch  30 . 
   When the slide plate  17  is moved in the direction reverse to the arrowed direction in  FIG. 7 , the movable side elastic piece  15   b  of each contact pin  15  returns to its original position, and the solder ball  12   b  is clamped between the contact portion  15   f  of the movable side elastic piece  15   b  and the contact portion  15   e  of the stationary side elastic piece  15   a  to thereby establish an electrical connection therebetween. In the state that the solder ball  12   b  is clamped between the contact portions  15   e  and  15   f , the stationary side elastic piece  15   a  is also elastically deformed slightly in a direction along which the contact portion  15   e  of the stationary side elastic piece  15   a  is widened. According to the motion mentioned above, the solder balls  12   b  of the IC package  12  and the printed circuit board are electrically connected through the contact pins  15 . 
   As mentioned hereinabove, The IC packages  12  are held by the IC sockets  11 , respectively, and the printed circuit board mounted with these IC sockets  11 , are set in a burn-in tank or vessel, and a temperature in the burn-in tank is increased to, for example, 125° C., to perform the burn-in test of the IC package  12 . 
   In the next stage, when the IC packages  12  is dismounted from the accommodated state, the operation member  23  is first lowered. Then, as mentioned before, the slide plate  17  is moved in the arrowed direction in  FIG. 7 , the movable side elastic piece  15   b  is elastically deformed, and the contact portion  15   f  of the movable side elastic piece  15   b  is then deformed from the state shown in  FIG. 23A  to the state shown in  FIG. 23B . According to this motion, the paired contact portions  15   e  and  15   f  are opened and separated from the solder ball  12   b  of the IC package  12 , and under this state, the IC package  12  can be taken out from the IC socket  11  by the automatic machine with no pulling force. 
   According to the structure and function of the IC socket of the described first embodiment, since the position of the rotation shaft  25  (i.e., force applying portion) is positioned on the side of the square slide plate  17  and at substantially the central portion in the slide plate moving direction, an external force is applied to the slide plate  17  from this central portion. Therefore, any external force is not applied to the end portion of the slide plate, which may be applied in the conventional structure, the slide plate  17  can be moved with its attitude or position being stably maintained. 
   Furthermore, the paired lever members  22  are disposed at the portions near the corner portions  17   c  on the diagonal line perpendicular to the moving direction of the slide plate  17 , so that a pair of lever members  22  having the same structure can be disposed on both sides of the slide plate  17 . On the other hand, it is difficult to arrange a pair of lever members having the same structure on a pair of corner portions  17   g  on the other diagonal line along the moving direction of the slide plate  17 . That is, in the described embodiment, the lever member  26  is disposed to one of the paired corner portions  17   g  on the other diagonal line along the moving direction of the slide plate  17  so as to be pulled in its moving direction, but, on the other one of the paired corner portions  17   g , a structure for pushing the slide plate  17  is to be adopted, so that lever members  26  having the same structure are not disposed at the paired corner portions  17   g  on the other diagonal line. 
   Still furthermore, in an occasion when a number of movable side elastic pieces  15   b  are elastically deformed by moving the slide plate  17 , a large force is applied to the slide plate  17 . However, in the described embodiment, since metallic support plate  24  is disposed to the rear end side portion in the moving direction of the slide plate  17 , the deformation of the slide plate  17  will be suppressed. 
   Moreover, the rotation shaft  25  (force applying portion) of the lever member  22  is coupled to the support plate  24  so as to transmit the driving force to the slide plate  17  through the support plate  24 . Therefore, a force to be applied to the slide plate  17  is dispersed to thereby prevent the concentration of load, thus moving the slide plate  17  in a stable attitude. 
   In addition, the lever members  22  and  26  are arranged such that the force applied portions  22   a  and  26   a  and the force support portions  22   b  and  26   b  take substantially the same height levels in the state that the lever members are maximally pressed downward, i.e., that the slide plate  17  is maximally moved, as shown in  FIG. 22 . Accordingly, the pressing force to the operation member  23  in this state can be made relatively small, thus being advantageous. 
   That is, although, under this state, the reaction force from the movable side elastic piece  15   b  is made maximally large, since the force applied portions  22   a  and  26   a  and the force support portions  22   b  and  26   b  take substantially the same height levels, a force F for depressing the operation member  23  acts as it is, with substantially no loss, as a force to rotate the lever members  22  and  26 , and such force acts as a force to move the slide plate  17  via the rotation shafts  25  and  27  (force applying portions), thus making relatively small the force to press the operation member  23 . 
   In the above embodiment, the lever member  26  is optional one and it may be eliminated from location. 
   [Second Embodiment] 
   The second embodiment of the present invention will be described hereunder with reference to  FIGS. 25 to 28 . 
   This second embodiment differs, from the first embodiment, in the “driving mechanism” for the slide plate  17 . 
   That is, this “driving mechanism” comprises two first links  35  in form of thin plate and a second link  36  disposed between these two first links  35 . One end portion  35   a  of each first link  35  is coupled to the end portion  24   a  of the support plate  24  to be pivotal around a shaft  37  (force applying portion) and the other end portion  35   b  of the first link  35  is coupled to the second link  36  by means of shaft  38  to be pivotal. The second link  36  has a base end portion  36   a  which is coupled to the socket body  13  to be pivotal by means of shaft  39  (force support portion) and has front end portion  36   b  (force applied portion) to be pressed by the operation member  23 . 
   In the structure of the second embodiment, when the operation member  23  is lowered and the front end portion  36   b  of the second link  36  is depressed downward, the second link  36  is rotated downward about the shaft  39  from the state shown in  FIG. 26  to the states shown in  FIG. 27  and then in  FIG. 28 .  FIG. 28  shows a state in which the second link  36  is rotated downward maximally. 
   According to this operation, the support plate  24  is pressed in the arrowed direction in  FIG. 27  through the shaft  37  (force applying portion) of the first link  35  to thereby move the slide plate  17  in the arrowed direction. 
   The other structures and operation or functions of this second embodiment are substantially the same as those of the first embodiment, so that the detailed explanation thereof is omitted herein. 
   It is further to be noted that the present invention is not limited to the described embodiments and many other changes and modifications may be made without departing from the scopes of the appended claims. 
   For example, in the described embodiments, although the present invention is applied to the IC socket referred to as “socket for an electrical part”, the present invention may be otherwise applicable to other like devices. 
   In the described embodiment, although the contact pin  15  includes a pair of elastic pieces  15   a  and  15   b  both having elastic property, contact pin can have only one elastic piece. 
   In addition, a structure, in which the slide plate  17  is moved in a direction parallel to the side of the square shape thereof as shown in  FIG. 29  in place of the diagonal direction, may be adopted. That is, in such modification, a box-shaped support plate  24  is provided for the slide plate  17  and the lever members  22  are mounted to both end portions  24   a  of the support plate  24  through the pivotal shaft  25  (force applying portion). The pivotal shaft  25  is positioned at substantially the central portion of the side portion of the slide plate  17  in its moving direction. 
   Furthermore, the driving mechanism for the slide plate is not limited to the described ones and another mechanism may be adopted as far as it can convert the vertical force to the horizontal force to move the movable member in the horizontal direction. 
   Furthermore, although in the described embodiment, the lever member  26  is provided, it is not indispensable.