Abstract:
A socket ( 100 ) of the present invention includes a base member ( 20 ), a cover member ( 30 ), a plurality of contacts ( 40 ), a latch member ( 60 A) that is rotatably supported by the base member ( 20 ) and rotates in response to movement of the cover member ( 30 ), an adaptor ( 50 ) providing a mounting surface for an IC package and attached with the base member ( 20 ) so as to move in an up and down direction in response to the movement of the cover member ( 30 ), and a latch plate ( 200 ) rotatably attached with the adaptor ( 50 A) and urged by an elastic member. The adaptor ( 50 A) is formed with a latch guide ( 58 ) that moves the latch plate ( 200 ) in the vertical direction when the latch plate ( 200 ) presses the IC package.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a socket for a semiconductor device, and more particularly, relates to a socket for a semiconductor device with terminals arranged in a two dimension array such as BGA (Ball Grid Array) and LGA (Land Grid Array) packages. 
     BACKGROUND OF THE INVENTION 
     Semiconductor devices such as BGA and LGA packages are subjected to a burn-in test prior to shipment, which applies stresses due to a high temperature to the semiconductor device. This eliminates devices in advance in which failures would occur in a certain period after shipping. Sockets used for the burn-in test generally are in two types. One is an open-top type socket whose cover member is vertically reciprocated. The other is a clamshell type socket whose cover member is rotated. For an open-top type socket, JP published application No. 2009-140629, U.S. Publication No. 2010-0248518 A1 (patent document 1) which is incorporated herein by reference, for example, discloses a socket that enables mounting and removing precisely an electronic device including surface mounted semiconductor devices such as BGA and Chip Scale Package (CSP) devices. 
     BRIEF DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  shows a configuration of a conventional socket described in the patent document 1.  FIG. 1(   a ) is a plan view,  FIG. 1(   b ) is a side view, and  FIG. 1(   c ) is a front view.  FIG. 2  is a sectional view taken at line X-X of  FIG. 1(   a ).  FIG. 3  is a perspective view showing the appearance of the socket. 
     A socket  10  includes a base member  20  made of an electrically insulated resin, a cover member  30  made of an electrically insulated resin and reciprocatably movable to be adjacent to or separated from the base member  20 , and a plurality of contacts  40  mounted in the base member  20 . 
     As shown in  FIG. 2 , the plurality of contacts  40  corresponding to the number of terminals of the BGA Chip to be mounted in the socket are positioned and aligned in the X and Y directions respectively in the center of the base member  20 . The mounting methods of contacts  40  includes, for example, the use of a separator type that laminates the aligned contacts with a separating sheet made of an insulating material alternately, or another type wherein each contact is inserted into a hole of a matrix array in a molded unit of the socket. 
     A contact unit  24  is inserted from the lower of base member  20  and fixed with the base member  20  so that the lower surface of contact unit  24  can be conformed with the bottom surface of the base member  20 . The lower end of each contact  40  is projected from the bottom surface of the base member  20  and the upper end of each contact  40  is positioned to be able to be electrically contacted with each solder ball of BGA package. A curved elastically deformable portion (not shown in the drawings) is formed between the lower and upper ends of the contact, which generates a necessary contact pressure between the upper end of the contact  40  and the solder ball. 
     An upstanding post  31  is provided at each corner of the cover member  30 , a coil spring  32  is wound around each post  31  to urge the cover member  30  constantly in an upward direction (open position) to be separated from the base member  20 . A pair of slots  34  that define the vertical stroke of the cover member  30  are formed in the opposite sidewalls  33  of the cover member  30  and each slot is engaged with a rotational axis member  61  of a latch member  60 . When the rotational axis member  61  is contacted with the lowest end of the slot  34 , the cover member  30  is in a most separated position (open position) from the base member  20 . When the rotational axis member  61  is contacted with the highest end of the slot  34 , the cover member  30  is in a closest position to the base member  20  (closed position). A rectangular aperture  35  is formed at the center of cover member  30  for mounting, for example, a BGA package on an adapter or mounting member  50  through the aperture  35 . 
     The adapter  50  is movable in a up and down direction and is attached on an adapter mounting surface  26  at the center in the base member  20  with the adaptor  50  providing a mounting surface  52  for BGA package as shown in  FIGS. 4 and 5 . A pair of hooks  54  is provided at the both sides of the adaptor  50  for engagement with a pair of apertures respectively formed in the base member  20 . The adapter  50  is biased by a coil spring, which is not shown in the drawings and is supported by the engagement of the hooks  54  in the apertures. When a large force is applied against the adaptor  50 , the adaptor  50  descends against the coil spring. The adaptor  50  is formed with a plurality of through holes  55  in the mounting surface  52 , the through holes  55  corresponds to the positions of each contact  40 . The upper end of each contact  40  projects from the adaptor mounting surface  26  and extends into the through hole  55 . When the adaptor  50  is in its upper most position urged by the coil spring, the upper end of each contact  40  remains in the through hole  55  without projecting from the mounting surface  52 . 
     Also, the mounting surface  52  of the adaptor  50  is formed with upstanding guide portions  56  at its periphery and the guide portions  56  include an inclined surface. The guide portion  56  guides the BGA package along the inclined surface onto the mounting surface  52 . Additionally, a plate guide portion  58  for guiding a latch plate  70  in the vertical direction is formed adjacent to the guide portion  56 . The plate guide portion  58  has a step structure including an inclined surface  58   a  and a vertical surface  58   b  and a latch plate  70  (to be described below) is moved along the plate guide portion  58  by contacting it, so that a pressing portion of the latch plate  70  is allowed to move in a vertical direction while being parallel with the mounting surface  52  and the upper surface of BGA package, without an arc movement. A positioning mechanism, which is not shown in the drawings, is installed at a corner  59  of the adaptor  50 . The positioning mechanism is operated by the reciprocating movement of the cover member  30  and includes pressing member that moves in a diagonal direction of the mounting surface  52 . By pushing BGA package at the diagonal direction with the pressing member, the BGA package is positioned. 
     The latch member  60  includes, as shown in  FIG. 6 , a pair of rotational axis members  61  formed at both sides, a pressing portion  64  having an arc-shaped surface which extends from the rotational axis member  61  at one side, and an extending portion  66  extending from the rotational axis  61  at the other side. The pressing portion  64  is formed with a pair of cylindrical projecting portions  62  at the both sides and the extending portion  66  is formed with an elongated hole  63  along the extending direction. The pair of the latch members  60  is attached with the base member  20  so as to be rotated around the rotational axis members  61 . 
     As shown in  FIG. 7 , the latch member  60  is disposed in a space between a pair of sidewalls  72  of the latch plate  70  and the latch plate  70  is attached to the top of the pressing portion  64  of the latch member  60 . That is, each projecting portion  62  of the latch member  60  is inserted into each slot  74  of the latch plate  70 . The width of the slot  74  in the shorter side is slightly larger than the diameter of the projecting portion  62 , thereby allowing the projecting portion  62  of the latch member  60  to be able to move in the slot  74  at the perpendicular direction with respect to the axis and to rotate around the projecting portion  62  as the fulcrum. A coil spring  67  is intervened between a projecting portion  79  of a pressing portion  78  of latch plate  70 , and a recess portion of the latch member  60 , and the projecting portion  62  is abutted to one end of the slot  74  by the coil spring  67  to urge the latch plate  70  so as to be separated. 
     The rotational axis member  61  of the latch member  60  is attached with the base member  20 , and when the latch member  60  is rotated in response to the movement of the cover member  30 , two projecting portions  76  provided at the sidewalls  72  of the latch plate  70  are slid on the plate guide portion  58  of the adaptor  50 . This is the vertical movement along the plate guide portion  58 , which is different from the arc movement of the latch member  60 . As show in  FIG. 2 , links  80  are disposed at the both sides of a pair of the latch members  60 . An axis member  82  provided at one end  81  of the link  80  is received in the elongated hole  63  of the latch member  60 . Other end  83  of the link  80  is rotatably supported by the cover member  30  through an axis member  84 . Additionally, the one end  81  of the link  80  is able to slide on the cam surface  28  formed at the base member  20 . 
     When the cover member  30  is moved downward toward the base member  20  and the axis member  82  of the link  80  comes in contact with the cam surface  28 , then the rotation of the link  80  around the axis is started. The one end  81  of the link  80  starts to slide following the can surface  28 , whereby the axis member  81  of the link  80  is guidedly moved in the elongated hole  63 , so that the latch member  60  is rotated around the axis member  61 . Top of the latch member  60  is rotated outside as if it depicts the arc trajectory from the position above the adaptor  50 . When the cover member  30  is fully stroked or fully pushed down, the top of the latch member  60  and the latch plate  70  are moved to the outermost position or the evacuated position away from the adaptor mounting surface  52 . 
     By pushing down the cover member  30 , the link  80  is rotated in response to the movement, the latch member  60  is rotated in response to the rotation of the link  80 , and top of the latch member  60  and the latch plate  70  are moved to the evacuated position from the mounting surface  52 . At this time, socket  10  is positioned for receiving BGA package on the mounting surface  52  of the adaptor  50  through the opening  35  in the cover member  30 . The BGA package is introduced along the guide portion  56  of the adaptor  50  and seated on the mounting surface  52  of the adaptor  50 . At this time, the adaptor  50  is kept upward by the coil spring, thus the top ends of each contact  40  remains in the through hole  55  without projecting from the mounting surface  52 . Accordingly, in this case when the BGA package is seated on the mounting surface  52 , the top ends of each contacts  40  are not contacted with the solder balls  3 . 
     When the cover  30  is moved upward, then the link  80  is also moved upwardly, thereby causing the latch member  60  to rotate and the latch plate  70  connected with the top of the latch member  60  to also move inside toward BGA package  1 . Before the pressing portion  78  of the latch plate  70  is contacted with the BGA package  1 , the projecting portion  76  of the latch plate  70  comes in contact with the vertical surface  58   b  of the plate guide portions  58  that are formed in the adaptor  50  and the movement of the latch plate  70  is changed from a rotational one by the latch member  60  to a vertical one, thus the pressing portion  78  is descended while keeping the parallel position with respect to of the BGA package. This allows the latch plate  70  to press the top surface of the BGA package from straight above without a circular or horizontal motion. At this movement, the contact point of the pressing portion  64  of the latch member  60  is slid on the pressing portion  78  of the latch plate  70  in a horizontal direction. 
     In response to the further upward movement of the cover member  30 , the BGA package  1  is further pushed down by the latch plate  70 . This results in the top end of each contact  40  being projected from the mounting surface  52  of the pressed adaptor  50  for contacting with the solder balls. Furthermore, the latch member  60  pushes down the BGA package  1  by rotating around the rotational axis member  61  until the spring force lifting the cover member  30  up and the contacting force of the contacts  40  are balanced. That is, the contacts  40  are distorted elastically for generating a contact force corresponding to the force (pressure force) by the latch member  60 , which thereby allows the contact  40  to make electrical contact with the solder ball  3 . 
     Using the latch plate  70  prevents the top surface of the BGA package from being scratched and allows the BGA chip to be pressed only in the vertical direction. However, since the width of the latch plate is restricted by the width of the latch member, there are problems with obtaining a larger area for pressing on an IC package, especially for a large sized IC chip. In addition, in the case of thin IC chip, the IC chip can be easily deformed by the reaction force from the contacts, which makes it desirable to press the whole surface of the IC chip. 
     The purpose of this invention is to provide a socket that solves the conventional problems and especially as they relate to large sized and thin IC chips. 
     Further, the purpose of this invention is to provide a novel socket that distributes the reaction force from the contacts to an electrical device and prevents the deformation of the electrical device by pressing the whole surface of the electrical device. 
     A socket according to the present invention comprising, a base member, a cover member movably attached with the base member, the cover member reciprocating to be adjacent to and/or separated from the base member, a plurality of contacts, each contact fixed with the base member and having an elastically deformable portion between first and second ends; a latch member rotatably supported with the base member, the latch member rotating in response to the position of cover member, the latch member being in a position that the latch member can press an electronic device when the cover member is in a separated position from the base member, and the latch member being in an evacuated position when the cover member is in an adjacent position to the base member, a mounting member attached with the base and providing a mounting surface for the electronic device, the mounting member movable in a rising and falling direction in response to the position cover member, and a latch plate rotatably attached with the mounting member and urged at a first direction by an elastic member. The mounting member is formed with a latch plate guide that moves the latch plate in the vertical direction when the latch plate presses the electronic device. The latch member makes the latch plate rotate at a second direction opposed to the first direction by contacting with the latch plate when the latch member is moved from the evacuated position to the pressable position. 
     Preferably, the latch plate includes a flat surface nearly parallel to the surface of the electronic device when the latch member is in the pressable position and latch plate is moved in the vertical direction. Preferably, a pair of latch members is disposed in opposition of each other with a pair of latch plates likewise disposed so as to correspond to the pair of latch members, the pair of latch plates pressing substantially whole surface of the electronic device. Preferably, the latch plate includes a pair of sidewalls and a pressing portion connecting the sidewalls, the pair of sidewalls formed with axis member that is rotatably engaged with the mounting member, opposing ends of the pressing portion are formed with tabs that extend outside the sidewalls. Preferably, the mounting member is formed with guides for introducing the electronic device and wherein the pressing portion of the latch plate is positioned at the same position as the guides or behind the guides when the latch plate is rotated at the first direction. Preferably, the latch plate includes a projecting portion, the projecting portion sliding in the latch plate of the mounting member in a vertical direction. Preferably, the latch plate includes a pair of sidewalls and a pressing portion connecting the sidewalls, the pressing portion having a first flat main surface which is contactable with the top surface of the electronic device, the latch member received between the sidewalls, the pressing portion of the latch member pressing a second main surface opposing to the first main surface. Preferably, the socket further includes a coil spring wound around an axis that urges the latch plate in the first evacuated direction, then when the latch plate is moved to the pressing position, the contacting portion of the latch member will slide on the second surface of the latch plate thereby moving the latch plate in the vertical direction. Preferably, the mounting member is formed with a plurality of through holes at the mounting surface, each through hole corresponding to each contact. The first end of each contact will project from the mounting member when the mounting member is moved toward the base member due to the force by the latch plate on the electronic device. 
     TECHNICAL ADVANTAGE OF THE INVENTION 
     According to the present invention, by only having vertical movement of the latch plate and by enlarging the area of the latch plate and by expanding the pressing area, the scratches and damages for ultra thin semiconductor packages due to the latch member are reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a conventional socket.  FIG. 1(   a ) is a plan view,  FIG. 1(   b ) is a side view, and  FIG. 1(   c ) is a front view; 
         FIG. 2  is a sectional view taken at X-X line in  FIG. 1(   a ). The left half of  FIG. 2  shows that the cover member is urged upward and the latch member is in a position ready to press. The right half shows that the cover member is fully stroked downwardly and the latch member is in an evacuated position; 
         FIG. 3  is a perspective view for showing the appearance of the socket; 
         FIG. 4  shows an adaptor.  FIG. 4(   a ) is a plan view,  FIG. 4(   b ) is a side view, and  FIG. 4(   c ) is a front view; 
         FIG. 5  is a sectional view taken at X 1 -X 1  line in  FIG. 4(   a ); 
         FIG. 6  shows a latch member; 
         FIG. 7(   a ) is a plan view of a conventional latch plate.  FIG. 7(   b ) shows a connection of the latch member and the latch plate; 
         FIG. 8  is an exemplary plan view of a socket according to an embodiment of the present invention; 
         FIG. 9  is a sectional view taken at X 2 -X 2  line of the socket according to an embodiment of the present invention; 
         FIG. 10  shows the latch plate according to an embodiment of the present invention.  FIG. 10(   a ) is a top view and  FIG. 10(   b ) is a front view; 
         FIG. 11  shows an adaptor according to an embodiment of the present invention.  FIG. 11(   a ) is a plan view and  FIG. 11(   b ) is a front view; 
         FIG. 12  is a plan view showing the relationship between the latch plate and the latch member according to an embodiment of the present invention; 
         FIG. 13  is an exemplary sectional view showing movement of a socket according to an embodiment of the present invention; 
         FIG. 14  is an exemplary sectional view showing movement of a socket according to an embodiment of the present invention; 
         FIG. 15  is an exemplary sectional view showing movement of a socket according to an embodiment of the present invention; and 
         FIG. 16  is a socket according to another embodiment of the present invention.  FIG. 16(   a ) shows an example of the size of a BGA package.  FIG. 16(   b ) is an exemplary plan view of the socket. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A socket according to present invention is preferably carried out as a test socket and described hereinafter with reference to the figures in detail. It should be noted that the scale in the figures is represented to understand the present invention easily and it does not express the actual scale of products. 
       FIG. 8  is a plan view of an exemplary socket according to an embodiment of the present invention. The socket  100  according to the embodiment has basically the same configuration as the conventional socket  10  described in  FIGS. 1 to 7 , however the socket  100  includes a latch plate  200  that is newly designed. In this embodiment, the latch plate  200  is, as described hereinafter, rotatably attached with the adaptor or mounting member  50 A so as to align with the latch member  60 . This allows the latch plate  200  to press the whole top surface of a semiconductor device such as a BGA package uniformly which is especially useful with large-sized and/or thin IC packages. 
       FIG. 10(   a ) is a top view of the latch  200  of the embodiment and  FIG. 10(   b ) is a front view of it. The latch plate  200  includes a pair of sidewall  210   a ,  210   b  (collectively, sidewall  210 ) oppositely opposing each other with a plate like pressing portion  220  connecting the two sidewalls  210   a ,  210   b . The pressing portion  220  is a generally rectangular-shaped and includes a flat surface at least at its bottom. Also, the upper surface of the pressing portion  220  is formed with rib  222  with a predetermined height along the periphery of it for reinforcement. Furthermore, rectangular-shaped tabs  220   a ,  220   b  extending beyond the sidewalls  210   a ,  210   b  are provided at the opposite ends of the pressing portion  220 . The tabs  220   a ,  220   b  are received in a notch portion (clearance portion)  56   a  (see  FIGS. 11 and 12)  of the adaptor  50 A when the latch plate  200  is rotated to the open position. The width W and length L of the pressing portion  220  can be suitably selected based on the outer size of the IC package to be mounted on the socket  100 . 
     The pair of sidewalls  210   a ,  210   b  extends nearly vertically from the both ends of the pressing portion  220 . Cylindrical axis members  230   a ,  230   b  that extend outward are provided at the sidewall  210   a ,  210   b , respectively. Each axis member  230   a ,  230   b  is received in a vertically elongated hole  59   a  (see  FIG. 11 ) formed in the adaptor  50 A, so that the latch plate  200  is movable within the longitudinal hole  59   a  in relation to the adaptor  50 A and is rotatably attached therewith. Each axis member  230   a ,  230   b  includes an extended portion  232   a ,  232   b  inside the sidewall  210   a ,  210   b , and a spring coil  300  is wound around each extended portion  232   a ,  232   b  respectively. 
     Additionally, guide members  240   a ,  240   b  (collectively, the guide  240 ) extending outward are provided at the top of the sidewall  210   a ,  210   b  as shown in  FIG. 10(   a ). The guide members  240   a ,  240   b  are preferably cylindrical or round-shaped. The guide members  240   a ,  240   b  can move along the plate guide portion  58  (see  FIGS. 5 and 11)  adjacent the guide portion  56  of the adaptor  50 A. When the guide members  240   a ,  240   b  are slid on the plate guide portion  58 , the movement of the latch plate  200  is regulated in the vertical direction. 
     Each coil spring  300  is wound around the extended portions  232   a ,  232   b  of the sidewalls  210   a ,  210   b . One end of each coil spring is fixed in a hole  250  formed in the rib  222  of each sidewall  210   a  and  210   b  and the other end of each coil spring  300  is fixed at a predetermined position of the adaptor  50 A. Thus, the latch plate is constantly urged in a direction to be separated from the mounting surface  52  of adaptor  50 A by the coil springs  300 . 
       FIG. 11  shows a plan view of the adaptor according to present invention and a sectional view taken at X 3 -X 3  line. The adaptor (mounting member)  50 A according to this embodiment is basically the same as the conventional adaptor  50  described in  FIG. 4 . In the adaptor  50 A of this embodiment, a notch portion  56   a  is formed adjacent the guides  56  at the corner of the mounting surface  52 . The notch portion  56   a , as described above, receives the tabs  220   a ,  220   b  when the latch plate  200  is rotated to the evacuated open position. At the lower position of the notch portion  56   a , a longitudinal hole  59   a  is formed which receives the axis members  230   a ,  230   b  of the latch plate  200  so that the latch plate  200  can be slid and rotated. As the result, the latch plate  200  can move vertically starting from the position slightly above the BGA package when the latch plate  200  is being position to move in contact with the top surface of the BGA package while also tolerating the thickness of the BGA package. 
       FIG. 12  shows the relationship between the latch member  60 A and the latch plate  200  when the BGA package  1  is removed from the position shown in  FIG. 8 . The latch member  60 A according to this embodiment has substantially the same configuration as the conventional latch member  60 , except that the latch member  60 A does not need the axis members  62  of the conventional latch member  60  as shown in  FIG. 6  for rotatably supporting the latch plate  70 . When the latch member  60 A presses the BGA package  1 , the latch member  60 A is placed in a space between the sidewalls  210   a ,  210   b  of the latch plate  200  and the top of the latch member  60 A presses the BGA package  1  through the pressing portion  220 . 
     Next, the operation of the socket according to the embodiment of the present invention is explained. When the IC package is to be mounted, the cover member  30  is pushed down from the open position as show in the left side of  FIG. 9 . In response to the movement downward, the link  80  is rotated and the latch member  60 A is rotated around the axis member  61  by the rotation of the link  80 . Thus, the top of the latch member  60 A is started to be moved to its evacuated open position separated from the mounting surface  52  of the adaptor  50 A. At the same time, the latch plate  200  is started to be released from the latch member  60 A, so that the latch plate is rotated so as to be separated from the mounting surface  52  due to the force of the coil spring  300 . Now, the latch plate  200  is positioned so that the end of the latch plate  200  can be abutted to a stopper  50   a  of the adaptor  50 A. At this moment, the tabs  220   a ,  220   b  at both sides of the latch plate  200  are received in the notch portion  56   a , the pressing portion  220  of the latch plate  200  becomes nearly upright, and the bottom surface of the pressing portion  220  is aligned with the guide  56  of the adaptor  50 A or behind the guide  56 . Now, the BGA package  1  can be dropped through the opening  35  of the cover member  30 , and then positioned by the guide  56  and/or the bottom surface of the pressing portion  220 , and eventually seated on the mounting surface  52 . At this same time, the top end of each contact  40  is not projecting from the mounting surface  52 , thus each contact  40  is not contacted with the solder balls of the BGA package  1 . 
     Next, as the force for pressing the cover member  30  is gradually reduced after the mounting of BGA package  1 , the cover member  30  moves upward. In response to this movement, the link  80  is also moved upward and the one end of the link  80  makes the latch member  60 A rotate around the axis member  61  so that the top of the latch member  60 A can be rotated. Then, latch member  60 A is rotated by a predetermined angle, and then the top of the latch member  60 A is contacted with the pressing portion  220  of the latch plate  200 .  FIG. 13  shows this condition. As the cover member  30  is continuously moved upward, the latch member  60 A is further rotated. At this moment, the latch member  60 A is rotated together with the latch plate  200  against the coil spring  300  as shown in  FIG. 14 . 
     Next, as the cover member  30  is further moved upward, the latch member  60 A is rotated around the axis member  61 , and the guide  240  of the latch plate  200  is contacted with the latch plate guide portion  58  of the adaptor  50 A just before the latch member  60 A is contacted with the top surface of the BGA package  1  on the mounting surface  52  as shown in  FIG. 15 . Thereafter, the rotation of the latch plate  200  is restricted and the latch plate  200  is moved within the longitudinal hole  59   a  only in the vertical direction. Although the latch member  60 A is further continued to rotate around the axis member  61  in response to the movement of the cover member  30 , the top of the latch member  60 A is slid in the horizontal direction H on the top surface of the pressing portion  220  and presses the latch plate  200  in the vertical direction V due to the rotation of the latch plate  200  being restricted. In other words, the latch member  60 A is slid in the horizontal direction H on the latch plate  200  while moving together with the latch plate  200  which moves in the vertical direction during pressing. 
     Due to the pressing force/movement of the latch member  60 A and the latch plate  200  in the vertical direction, the adaptor  50 A moves downwardly against the spring urging force on it so that the top end of each contact  40  is projected from the mounting surface  52  of the adaptor  50 A to make contact with each solder ball of the BGA package  1 . As shown in  FIG. 8  the BGA package  1  has a size corresponding to the mounting surface of the adaptor  50 A. In the conventional latch plate, the area for pressing package  1  is limited by the width of the latch plate (space between the pair of the sidewalls  210   a ,  210   b ). In other words, the conventional latch plate cannot press the entire surface of the BGA package. In contrast, the latch plate  200  according to this embodiment increases the pressing area compared with the conventional latch plate by having the additional pressing area of tabs  220   a ,  220   b  extending outside the sidewalls  210   a ,  210   b.    
     When the BGA package is to be removed, the cover member  30  is pushed down from the top, open position which causes the latch plate  60 A to be rotated from the pressing position to the evacuated position. The latch plate  200  is restricted to move at vertical direction until the guide  240  is disengaged with the latch plate guide portion  58  of the adaptor  50 A. After disengagement, the latch plate  200  is rotated around the axis members  232   a ,  232   b  (shown in  FIG. 10 ) and is opened as shown in the right side of  FIG. 9 . 
     Another embodiment according to the present invention is explained hereinafter.  FIG. 16(   a ) shows a schematic planar view of the BGA package with the external dimension M×N. A pair of latch plates  200  is attached with the socket, the width W of each latch plate  200  is equal to the length M of the package and the length L is substantially equal to half of the length N. The cross-hatching area of  FIG. 16(   b ) shows the area pressed by the latch plate is substantially all of surface of the BGA package. Accordingly, with this embodiment, the entire surface of the BGA package can be pressed uniformly by the latch plate  200 . 
     Although the preferred embodiment according to the present invention has been described, variations and modifications that may occur to those skilled in the art, should be considered to be within the scope of the present invention.