Socket for electrical parts

[0002] 1. Field of the Invention

[0003] The present invention relates to a socket for electrical parts for detachably accommodating an electrical parts such as a semiconductor device or the like (hereinafter referred to as “IC package”), more particularly relates to a socket for electrical parts capable of easily replacing a contact pin that contacts with or separates from a terminal of the electrical parts.

[0004] 2. Prior Art of the Invention

[0005] Conventionally, an IC socket as a “socket for electrical parts” is previously mounted on a circuit board and then accommodates an IC package on the IC socket, achieving an electrical contact between the IC package and the circuit board.

[0006] As for the IC packages, for example, those having numbers of terminals on a lower surface of a rectangular type package body have been exemplified.

[0007] Each of these terminals of the IC package is brought to electrically contact with said circuit board via each contact pin, by making each of the terminals of the IC package contact with an upper portion of the contact pin in the IC socket while the IC package is held on the IC socket.

[0008] As typically shown in FIGS. 21A and 21B, the contact pin 1 comprises an upper end portion 1athat abuts against and contacts with the terminal of the IC package, a lower end portion 1bthat abuts against and contacts with the circuit board and an approximately arcuate and elastically deformable elastic portion 1cbetween the upper portion 1aand the lower portion 1b.

[0009] The upper portion 1ais inserted into an upper through hole 3aformed to a floating plate 3 of the socket body 2 and the lower portion 1bis inserted into an lower through hole 4aformed to a base portion 4 of the socket body 2. The upper and lower portions each contact with the IC package and the circuit board under a prescribed contact pressure respectively, while the elastic portion 1cis elastically deformed. And the contact pin 1 is formed with a projection 1dfor preventing the contact pin 1 from dropping out.

[0010] In such an IC socket mentioned above, two major processes described below have been conceived when there is a need to replace the contact pin 1.

[0011] (1) At first, the base portion 4 and the floating plate 3 are taken apart, and then the contact pin 1 is taken out or inserted.

[0012] (2) At first, a damaged contact pin 1 is forcibly taken out without taking apart the base portion 4 and the floating plate 3, and then a new contact pin 1 is forcibly inserted.

[0013] The foregoing conventional processes have following disadvantages. That is, in the above mentioned process (1), there is certainly no need to apply too much force in taking out or inserting the contact pin 1. But at the time when the floating plate 3 is made to attach to the base portion 4, the process of inserting all contact pins 1 into the upper through holes 3aof the floating plate 3 must be done, being a difficult process. On the other hand, in the above mentioned process (2), damages may occur at a peripheral portion of the upper through hole 3aof the floating plate 3 at the time the contact pin 1 is forcibly taken out upwardly, and plastic deformation also may occur at the projection 1d at the time when the contact pin 1 is forcibly inserted, because there is the peripheral portion around the upper through hole 3aof the floating plate 3. Therefore, forcible insertion or takeout of the contact pin 1 is a difficult process in replacing the contact pin 1.

[0014] Accordingly, when only one or a few contact pins are damaged among numbers of them, the IC socket itself having a damaged contact pin must be replaced with a new one, being inconvenient and expensive.

[0015] The processes of this kind are described in Japanese Patent Publication No. Tokkai Hei 6-89764.

[0016] An object of the present invention is aimed at substantially eliminating defects or drawbacks encountered in the prior art mentioned above and to provide a socket for electrical parts capable of easily replacing even only one of the contact pins without disassembling the socket body itself.

[0017] In order to achieve this or other objects of the present invention, an aspect of the present invention is that a socket for electrical parts comprises:

[0018] a socket body on which an electrical part is accommodated; and

[0019] a contact pin provided to the socket body,

[0020] the contact pin comprising;

[0021] an upper end portion to contact with a terminal of the electrical part,

[0022] a lower end portion to electrically contact with a circuit board,

[0023] an elastically deformable spring portion between the upper end portion and the lower end portion,

[0024] an elastic deformation portion formed in the upper end portion, and

[0025] an engaging portion formed on an end most portion of the elastic deformation portion,

[0026] the socket body comprising;

[0027] an upper through hole into which the upper end portion of the contact pin is inserted, and

[0028] a lower through hole into which the lower portion of the contact pin is inserted,

[0029] the contact pin being able to be installed in the socket body by inserting the lower end portion thereof via the upper through hole into the lower through hole, then inserting the upper end portion thereof into the upper through hole with the elastic deformation portion deformed, and then releasing the deformation of the elastic deformation portion at the time the insertion is completed, finally the engaging portion engaging with a lower surface portion of a peripheral portion of the upper through hole, to prevent the contact pin from being fallen out from the upper through hole.

[0030] According to the foregoing aspect of the present invention, elastic deformation at the elastic deformation portion of the contact pin allows the contact pin to be easily driven into or taken out of the socket body without dismantling the socket body, so that even only one of the contact pins can be easily replaced.

[0031] Another aspect of the present invention is that a contact surface portion extending in an approximately horizontal direction is provided on the upper end portion to abut against a spherical terminal of the electrical part, and a recess portion is provided on the contact surface portion to prevent a lower end portion of the spherical terminal from abutting against the contact surface portion.

[0032] According to the foregoing aspect of the present invention, since the recess portion is provided on the contact surface portion of the contact pin, the lowermost portion of the round shaped terminal of the electrical part is kept from being damaged.

[0033] Another aspect of the present invention is that the recess portion of the upper end portion of the contact pin has an ellipsoidal shape elongated in the bending direction of the spring portion.

[0034] According to the foregoing aspect of the present invention, when the contact surface portion of the contact pin is urged downwards with the round shaped terminal of the electric part being driven into the ellipsoidal recess of the contact pin, the contact surface portion is displaced. As the ellipsoidal recess is made elongated along the displacement direction, the round shaped terminal moves within the range of the ellipsoidal recess in a relative displacement manner with respect to the recess, resulting in that the displacement is allowed. Therefore, an unnecessary or excessive force does not apply on the round shaped terminal or the contact pin etc. In addition, a wiping effect can be exerted because the round shaped terminal slides within the recess in the relative displacement manner.

[0035] Another aspect of the present invention is that the contact surface portion extending in an approximately horizontal direction is provided on the upper end portion to abut against a plane like terminal of the electrical part, and a projection is provided on the contact surface portion to abut against the plane like terminal.

[0036] Still another aspect of the present invention is that an inclined guide portion is further provided at the upper peripheral portion of the lower through hole of the socket body, to help guide the lower end portion of the contact pin into the lower through hole.

[0037] According to the foregoing aspect of the present invention, the lower end portion of the contact pin can be easily inserted into the lower side through hole since the inclined guide portion is provided at the upper peripheral portion of the lower side through hole.

[0038] In the accompanying drawings:

[0039] FIG. 1 is a plan view of an open/close member of an IC socket of a first embodiment of the present invention, a lower half of an open/close member being opened;

[0040] FIG. 2 is a front view of the IC socket of the first embodiment;

[0041] FIG. 3 is a right side view of the IC socket of the first embodiment;

[0042] FIG. 4 is a front view of the IC socket of the first embodiment, a portion where contact pins are disposed is cut away;

[0043] FIG. 5 is an enlarged cross sectional view of the portion where contact pins are disposed in FIG. 4;

[0044] FIG. 6A, 6B and 6C show the contact pin of the IC socket of the first embodiment, FIG. 6A is a front view of the contact pin; FIG. 6B is a plan view of FIG. 6A; and FIG. 6C is a right side view of FIG. 6A;

[0045] FIG. 7 is a plan view of a base portion of the socket body of the IC socket of the first embodiment;

[0046] FIG. 8 is a front view of the base portion of the socket body of the IC socket of the first embodiment;

[0047] FIG. 9A, 9B, 9C and 9D are enlarged views of a part of the base portion of the socket body of the IC socket in the first embodiment, FIG. 9A is an enlarged view of X portion in FIG. 7; FIG. 9B is a cross sectional view taken along the line IXB—IXB in FIG. 9A; FIG. 9C is a cross sectional view taken along the line IXC—IXC in FIG. 9A; and FIG. 9D is an enlarged view of FIG. 9C, where the contact pin is inserted;

[0048] FIG. 10 is a plan view of a floating plate of the first embodiment, where a guide portion of the socket body of the IC socket is omitted;

[0049] FIG. 11 is a front view of the floating plate of the first embodiment, where the guide portion of the socket body of the IC socket is omitted;

[0050] FIGS. 12A and 12B are enlarged views of a part of the floating plate of the socket body of the IC socket in the first embodiment, FIG. 12A is an enlarged view of Y portion in FIG. 10 and FIG. 12B is a cross sectional view taken along the line XIIB—XIIB in FIG. 12A;

[0051] FIG. 13 is a plan view showing the open/close member and the pressing member etc. of the IC socket of the first embodiment;

[0052] FIG. 14 is a plan view corresponding to FIG. 13 at the time when the pressing member of the IC socket of the first embodiment is rotated;

[0053] FIG. 15 is a cross sectional view taken along the line XV—XV in FIG. 13 of the first embodiment;

[0054] FIG. 16 is a cross sectional view corresponding to FIG. 15, where the pressing member of the IC socket of the first embodiment is slanted;

[0055] FIGS. 17A and 17B are view showing the IC package to be accommodated on the IC socket in the first embodiment, FIG. 17A is a front view of the IC package and FIG. 17B is a bottom view of the IC package respectively;

[0056] FIGS. 18A and 18B are views showing the contact pin of a second embodiment of the present invention, FIG. 18A is a front view of the contact pin and FIG. 18B is a plan view of FIG. 18A respectively;

[0057] FIGS. 19A and 19B are views showing variations of an elastic deformation portion and a collar like engaging portion, FIG. 19A is a front view of the contact pin and FIG. 19B is a plan view of FIG. 19A, respectively;

[0058] FIGS. 20A and 20B are views showing another variations of the elastic deformation portion and the collar like engaging portion, FIG. 20A is a front view of the contact pin and FIG. 20B is a plan view of FIG. 20A respectively; and

[0059] FIGS. 21A and 21B are views showing conventional art, FIG. 21A is a cross sectional view showing an outline of an arranged state of the contact pin and FIG. 21B is a cross sectional view taken along the line XXIB—XXIB in FIG. 21A, respectively.

[0060] Preferred embodiments or best mode of the present invention will be described hereunder with reference to the accompanying drawings.

[0061] FIG. 1 to FIG. 17B show the first embodiment of the present invention.

[0062] First, a structure will be explained. In figures, reference number 11 shows an IC socket as a “socket for electrical parts.” The IC socket 11 is used for carrying out a performance test of the IC package 12 and for establishing an electrical contact between a solder ball 12bas a “spherical terminal” of an IC package 12 and a circuit board P on the side of an IC test equipment.

[0063] The IC package 12 is the so-called BGA (Ball Grid Array), and as shown in FIGS. 17A and 17B, numbers of solder balls 12bare formed in a matrix like manner on a lower surface of a square like package body 12a.

[0064] The IC socket 11 comprises, as typically shown in FIG. 1 to FIG. 4, a socket body 13 disposed on the circuit board P such as a burn-in board or the like, and a contact pin 14 disposed in the socket body 13 to be contacted with the solder ball 12b.

[0065] The contact pin 14, as shown in FIG. 6A, 6B and 6C, can be produced, for example, through a process of folding a long plate-like electrically conductive material using press working, and then forming, between an upper end portion 14aand a lower end portion 14b, a spring portion 14c, which is capable of being bent in a direction (arrow direction as shown in FIG. 6A).

[0066] A contact surface portion 14dextending approximately in a horizontal direction is formed on the upper end portion 14aand contacts with and separates from the solder ball 12bof the IC package 12. As shown in FIG. 6B, an ellipsoidal recess (recess portion) 14eelongated in a bending direction of a spring portion 14c(arrow direction in FIG. 6B) is provided on the contact surface portion 14din order to prevent a lower most portion of the solder ball 12bfrom contacting with the contact surface portion 14d. The length of the minor axis of the ellipsoidal recess is made shorter than the outer diameter of the solder ball 12b.

[0067] An elastic deformation portion 14fextends downwards from the contact surface portion 14d, and a lower end portion (endmost portion) of the elastic deformation portion 14fhas a collar-like engaging portion 14gthat is folded back.

[0068] Furthermore, a positioning projection 14ifor controlling a lower most position of the contact pin 14 is formed, as shown in FIG. 6A, 6B, 6C, FIG. 9A, 9B, 9C and 9D, on the lower end portion 14bof the contact pin 14, and engages with a lower through hole 15aof a base portion 15 as described later. The outer width W1 of the projection 14i, as shown in FIG. 6C, is formed narrower than the width W2 of the contact surface portion 14d.

[0069] The socket body 13, as shown in FIG. 4 etc., comprises a base portion 15 to be mounted on the circuit board P. and a floating plate 16 disposed at a prescribed distance from and over the base portion 15. The lower through hole 15ainto which the lower end portion 14bof the contact pin 14 is to be inserted, is formed to the base portion 15, as shown in FIG. 7 to FIG. 9A, 9B, 9C and 9D.

[0070] The floating plate 16, as shown in FIG. 1, is urged toward upper side by a spring 31 and can be moved vertically with respect to the base portion 15. An upper through hole 16ainto which the upper portion 14aof the contact pin 14 is inserted, is formed to the floating plate 16, as shown in FIG. 10 to FIG. 12A and FIG. 12B. The upper through hole 16ahas an upper surface side diameter W3 that is lager than a lower surface portion 16bside diameter W4, as shown in FIG. 12B. Furthermore, a frame-like guide member having a guide portion 16cwhich determines a position of the IC package 12, is embedded to the floating plate 16, as shown in FIG. 1.

[0071] The spring portion 14cof the contact pin 14 is, as shown in FIG. 5, disposed between the base portion 15 and the floating plate 16. The upper end portion 14aof the contact pin 14 is inserted into the upper through hole 16aof the floating plate 16, and the lower end portion 14bof the contact pin 14 is inserted into the lower through hole 15aof the base portion 15, respectively.

[0072] That is, the lower end portion 14bof the contact pin 14 is at first inserted into the upper through hole 16aand then into the lower through hole 15a. The upper end portion 14aof the contact pin 14 is inserted into the upper through hole 16awith the elastic deformation portion 14felastically deformed as shown by a long dashed two short dashed line in FIG. 5. In addition, at a state of completion of the insertion, the elastic deformation at the elastic deformation portion 14fis released and then the elastic deformation portion 14freturns to the original position so that upward dropout of the contact pin 14 from the socket body 13 can be prevented even if the contact pin 14 is pushed upwardly, because the collar-like engaging portion 14gengages with the lower surface portion 16bof the peripheral portion of the upper through hole 16a.

[0073] And at an upper peripheral portion of the lower through hole 15aof the base portion 15, an inclined guide portion 15bis formed to help guide and insert the lower end portion 14bof the contact pin 14 into the lower through hole 15a.

[0074] Furthermore, at the lower through hole 15a, as shown in FIG. 9D, a stepped portion 15cis formed to engage with the positioning projection 14iof the contact pin 14. The positioning projection 14iof the contact pin 14 abuts against the stepped portion 15cso that the lowermost position of the contact pin 14 can be controlled.

[0075] At the side of the base portion 15 of the socket body 13, as shown in FIG. 1 to FIG. 4, an open/close member 18 is mounted rotatably on an axis 19, and urged toward opening direction thereof by a spring 17. A press member 20 is attached to the open/close member 18 to press the IC package 12.

[0076] As shown in FIG. 13 and FIG. 15, an opening 18ahaving a rectangular shape is formed in a center portion of the open/close member 18. And a bearing portion 20aof the pressing member 20 is inserted into the opening 18a.

[0077] The pressing member 20 has a press board member 20bhaving a rectangular shape the size of which corresponds to the size of the IC package 12. The bearing portion 20aprojects from an approximately center portion of the press board portion 20b.

[0078] The bearing portion 20ahas engaging portions 20dprojecting toward outside of the sides of the bearing portion 20a. These engaging portion 20dare engaged with and supported by an engage portion 18cformed at the peripheral portion of the opening 18aof the open/close member 18. In this embodiment, the pressing member 20 is supported to be able to move vertically in relation to the open/close member 18. That is, there is a small amount of clearance in a vertical direction between the engaging portion 20dand the engage portion 18c. As shown in FIG. 14, the engaging portion 20dcan rotate from a state of solid line, which shows a state that the engaging portion 20dis in an engaging state with the engage portion 18c, to a state shown by a long dashed short dashed line to a state of a long dashed two short dashed line, so that the engaging state can be released, followed by releasing of the engaging portion 20dfrom the opening 18a, and finally the pressing member 20 can be taken out from the open/close member 18. At the time when the pressing member 20 is rotating, a corner portion of the engaging portion 20dis guided to slide on an arcuate-like guide wall 18d.

[0079] The bearing portion 20ais provided with a slit 20cextending vertically at a state when the open/close member 18 is closed (the open/close member 18 is in an approximately horizontal state). A shaft 21, a portion of which is to be inserted into an insertion hole 18bof the open/close member 18, is inserted into the slit 20c. The pressing member 20 is prohibited from rotating when the shaft 21 is in a state of insertion into the slit 20c, to prevent the pressing member 20 from falling off from the open/close member 18. And E-rings 22 are detachably provided on the shaft at around both side portions of the open/close member 22. The shaft can be drawn off by taking out at least one of the E-rings 22.

[0080] Furthermore, the shaft 21 is to be inserted into a pair of spacers 23 having a round shape (toric shape) in cross section parallel to an orthogonal direction of the shaft 21. The pair of spacers 23 are disposed within the opening 18aof the open/close member 18 and at both side portions of the bearing portion 20aof the pressing member 20. When the upper surface of the IC package 12 is pressed by the press board portion 20b, an outer surface (side surface) of the spacer 23 abuts against the press board portion 20b. The spacer 23 can be replaced by sliding the shaft 21 into or out of the spacer 23.

[0081] In addition, as shown in FIG. 1, 2 and 4, a latch member 25 is rotatably provided on a shaft 24 on the side of the base portion 15. A hook portion 25aprovided at an endmost portion of the latch member 25 is engaged with an endmost portion 18eof the open/close member 18. Furthermore, rotation of an arm 26 provided rotatably on the shaft 24 allows the latch member 25 to move vertically and rotatably under an action of a mechanism not shown in this embodiment. And the latch member 25 is urged upwards by a spring 27. More precise operations will be explained hereunder.

[0082] Next, operation of the socket will be explained.

[0083] The IC socket 11 is mounted beforehand on, as shown in FIGS. 2 and 3, the circuit board P via a support plate 30 by a bolt 28 and a nut 29.

[0084] As shown at lower half portion in FIG. 1, in a state where the open/close member 18 is opened, the IC package 12 is mounted on the floating plate 16, then the open/close member 18 is closed, to engage the hook portion 25aof the latch member 25 with the endmost portion 18eof the open/close member 18.

[0085] Next, as shown in FIG. 2, when the arm 26 which is in uprising position, is rotated to fall down toward an approximately horizontal position, the latch member 25 is forced to move downwards against an urging force of the spring 27, rotating and bringing the open/close member 18 to further downward position.

[0086] Force to rotate the open/close member 18 downwards is transferred to the press board portion 20bof the pressing member 20 via the shaft 21 and the spacer 23, resulting in a state that the package body 12aof the IC package 12 is pressed by the press board portion 20b.

[0087] The operation mentioned above makes the solder ball 12bof the IC package 12 contact with the contact surface portion 14dof the contact pin 14, with a prescribed contact pressure, establishing an electrical connection. At this time, as the solder ball 12bis inserted at the lower portion thereof into the ellipsoidal recess 14ehaving a minor axis narrower in width than the diameter of the solder ball 12b, the lowermost portion of the solder ball 12bcan be kept from being damaged.

[0088] In addition, when the contact surface portion 14dof the contact pin 14 is urged downwards with the solder ball 12bbeing driven into the ellipsoidal recess 14e, the contact surface portion 14dis displaced in a deformation direction of the spring portion 14c. The ellipsoidal recess 14eis elongated along the deformation direction of the spring portion 14eso that the solder ball 12bcan move within the ellipsoidal recess 14ein a relative displacement manner with respect to the recess 14e, resulting in that the displacement is allowed. Unnecessary and excessive force applying on the solder ball 12b, the contact pin 14eor the like can be eliminated. In addition, a wiping effect can be exerted because the solder ball 12bmoves within the recess 14ein the relative displacement manner with respect to the ellipsoidal recess 14e.

[0089] As mentioned above, when the IC package 12 is accommodated on the IC socket 11, electrical contact, via the contact pin 14, between the IC package 12 and the circuit board P is established. Then the burn-in test is carried out under this condition.

[0090] On the other hand, when the IC package 12 is taken out from the IC socket 11, the arm 26 is, at first, rotated anticlockwisely in an arrow direction from a state shown in FIG. 2, to bring the arm 26 to an uprising position. The latch member 25 is moved upwards by the urging force of the spring 27 with the latch member 25 rotating anticlockwisely, resulting in that the hook portion 25ais released from the endmost portion 18eof the open/close member 18.

[0091] Thereby, the open/close member 18 is rotated and opened by the urging force of the spring 17, being able to take out the IC package 12.

[0092] Incidentally, in a case where the contact pin 14 of the IC socket 11 is damaged and needs to be replaced, the contact pin 14 can be removed upwards and taken out without dismantling the floating plate 16, by unfastening the engaging portion 14gfrom an engage portion of the lower surface portion 16bof the floating plate 16 with the elastic deformation portion 14fof the contact pin 14 being elastically deformed, as shown by a long dashed two short dashed line in FIG. 5.

[0093] On the contrary, when a new contact pin 14 is fitted, the contact pin 14 can be inserted through and fitted into each through hole 15a, 16afrom upper side thereof with the elastic deformation portion 14fbeing elastically deformed.

[0094] Accordingly, the contact pin 14 can be easily removed from or installed in the socket body 13 without disassembling the base portion 15 and the floating plate 16, so that even only one of the contact pins 14 can be easily replaced.

[0095] What is more, the engaging portion 14gprevents the contact pin 14 from falling off.

[0096] When the contact pin 14 is driven to be inserted into each through hole 15a, 16afrom upper side of the socket body 13, it may be often difficult to insert the lower end portion 14bof the contact pin 14 into the lower side through hole 15a, because the lower side through hole 15ais a little bit apart from the upper side through hole 16a, and the lower side through hole 15acan not be seen from naked eye.

[0097] The lower end portion 14bof the contact pin 14 can be, however, easily inserted into the lower side through hole 15a, by providing the inclined guide portion 15bat the upper peripheral portion of the lower side through hole 15a.

[0098] Next, in a case where various IC packages 12 different in thickness thereof are tested using the same IC socket 11, the pressing member has usually been replaced with another one in order to secure a prescribed contact pressure in conventional art. According to the embodiment of the present invention, however, all one needs to do is to replace the spacer 23 having different thickness t1.

[0099] More specifically, the spacer 23 can be replaced by taking out the shaft 21 after unfixing one of the E-rings 22. The pressing member 20 of the present invention does not slip off unintentionally even in a state the shaft 21 is taken out, because the engaging portion 20dof the pressing member 20 remains engaged with the engage portion 18cof the open/close member 18.

[0100] Next, the spacer 23 having a different thickness t1 is first prepared and then the shaft 21 is inserted into the spacer 23, the slit 20cof the pressing member 20 and the open/close member 18 respectively, and then the shaft 21 is secured by the E-ring 22.

[0101] As the spacer 23 having a thickness t1 is interposed between the shaft 21 and an upper surface of the press board portion 20b, a clearance between the shaft 21 and the upper surface of the pressboard portion 20bcan be adjusted, by only replacing the spacer 23 without replacing the pressing member 20, so that the same IC socket 11 can be used for various types of IC packages 12 having different thickness, being able to secure a prescribed contact pressure.

[0102] When IC package 12 having different shape is accommodated, a pressing member 20 of the press board portion 20bhaving a corresponding shape should be used. In the present invention, however, the pressing member 20 can be easily replaced.

[0103] More specifically, the pressing member 20 is rotated by about 90° after the shaft 21 is taken out. Thereby, the engaging portion 20dof the pressing member 20 is released from the engage portion 18cof the open/close member 18 so that the engaging portion 20dcan be taken out through the opening 18a. On the contrary when a new pressing member 20 is installed, the engaging portion 20dof the pressing member 20 is inserted into the through hole 18aand rotated by about 90°, and then the engaging portion 20dof the pressing member 20 is engaged with the engage portion 18cof the open/close member 18. And then the shaft 21 is inserted and finally the shaft 21 is fixed by the E-ring 22, to complete the replacing process.

[0104] As the pressing member 20 can be easily replaced as mentioned above, the same IC socket 11 can be used for various kinds of IC packages 12 having different shapes, reducing cost in process.

[0105] As the engage portion 18cis engaging with the engaging portion 20dwhen in use even after the shaft is taken out, the open/close member 18 dose not fall off unintentionally. Thereby, there is no need to hold the pressing member while the shaft 21 is taken out, being an easy work for replacing the pressing member 20.

[0106] Further, the pressing member 20 can be engaged or taken out by only rotating the pressing member 20, improving workability in replacing the pressing member 20. Still furthermore, since the open/close member 18 is further provided with the guide wall 18dhaving an approximately arcuate shape for guiding the pressing member 20 at the time the pressing member 20 is rotated, rotation and replacing of the pressing member 20 can be carried out more easily.

[0107] FIGS. 18A and 18B show a second embodiment of the present invention.

[0108] In this second embodiment, a projection 14his formed on the contact surface portion 14dof the contact pin 14. Difference from the embodiment 1 resides in this feature.

[0109] The projection 14habuts against a plate-like terminal of the LGA (Land Grid Array) type IC package, not shown in Figs. The projection 14his formed on the contact surface portion 14dso that the contact pressure with the plate-like terminal can be secured.

[0110] In the present invention, the position of the elastic deformation portion 14fand the collar-like engaging portion 14gare not limited to the position of the first embodiment. As shown in FIG. 19A, 19B, FIG. 20A, 20B, the elastic deformation portion 14fand the collar-like engaging portion 14gcan be provided at any peripheral side of the contact surface portion 14d. 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.