Socket for electrical parts

A socket for an electrical part having a socket body has an electrical part accommodation portion and a contact pin is provided for the socket body so as to be contacted to or separated from a terminal of the electrical part. The contact pin has a contact portion, which projects upward over a through hole formed to the electrical part accommodation portion by a predetermined amount irrespective of an accommodation condition of the electrical part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a socket for an electrical part for detachably holding and accommodating an electrical part such as a semiconductor device (called as “IC package” hereinlater).

2. Related Art of the Invention

In a known art, there has been provided an IC socket, as “socket for an electrical part” for detachably holding and accommodating an “IC package” as an electrical part.

Such IC socket has a socket body which is provided with an IC package accommodation portion and to which a number of contact pins are arranged so as to contact the terminals of the IC package to thereby establish an electrical connection.

The socket body is further provided with a floating plate, having the IC package accommodation portion, to be vertically movable, the floating plate being formed with a number of through holes into which contact portions formed to the upper end side of the contact pins are inserted, respectively.

When the floating plate with the IC package being mounted thereon is pressed downward, the contact portions of the contact pins abut against, with predetermined contacting pressure, the terminals arranged to the lower surface of the IC package to there achieve the electrical connection therebetween.

In such conventional structure, however, the contact portions of the contact pins are positioned inside the through holes of the floating plate when the floating plate is positioned at its top dead center, so that the dust or like may invade into the through hole from upper portion thereof and stays in a gap between the contact portion of the contact pin and the terminal of the IC package, which may hence result in defective contact therebetween or constitute a bar for smooth relative movement between the contact portion of the contact pin and the floating plate.

SUMMARY OF THE INVENTION

The present invention conceived to obviate such defects or inconveniences encountered in the prior art mentioned above aims to provide a socket for electrical parts for effectively preventing the dust or like from invading into a through hole into which a contact pin is inserted.

This and other objects can be achieved according to the present invention by providing a socket for an electrical part having a socket body having an electrical part accommodation portion and a contact pin provided for the socket body so as to be contacted to or separated from a terminal of the electrical part, wherein the contact pin has a contact portion, which projects upward over a through hole formed to the electrical part accommodation portion of the socket body irrespective of accommodation condition of the electrical part.

In a preferred embodiment of this aspect, the socket body comprises a base portion and a floating plate disposed above the base plate to be vertically movable with respect thereto, the floating plate being formed with the through hole through which the contact pin is inserted. A plurality of mount projections may be formed on the accommodation portion of the floating plate for mounting the electrical part thereon each with a projection amount being larger than a projection amount of the contact portion of the contact pin at a time when the floating plate is positioned at a top dead center thereof.

More specifically, the present invention provides a socket for an electrical part comprising:a socket body having an electrical part accommodation portion;a contact pin provided for the socket body and formed with a contact portion to be contacted to or separated from a terminal of the electrical part;a pressing member for pressing the electrical part mounted on the accommodation portion of the socket body; andan operation member disposed for the socket body to be vertically movable so as to move the pressing member,wherein the electrical accommodation portion is formed with a through hole through which the contact portion of the contact pin projects outward by a predetermined amount irrespective of accommodation condition of the electrical part.

According to the above aspects and preferred embodiment of the present invention, the contact portion of the contact pin projects upward over the through hole formed to the electrical part accommodation portion of the socket body irrespective of the accommodation condition thereof. Therefore, any dust or like does not invade and stay in the through hole and a defective contact state between the contact portion of the contact pin and the terminal of the electrical part can be prevented from causing, and furthermore, the contact pin can carry out smooth relative movement in the through hole.

In addition, according to the subject features of the preferred embodiment, in the case where the electrical part is accommodated and mounted on the mount projections at the time when the floating plate of the socket body is positioned at its top dead center, the terminal of the electrical part is free from contacting to the contact portion of the contact pin, thus preventing the electrical part terminal and the contact portion of the contact pin from contacting to each other and being damaged thereby.

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.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described hereunder with reference to the accompanying drawings ofFIGS. 1to19. Further, it is first to be noted that terms “right”, “left”, “upper”, “lower” and the like are used herein with reference to the illustrated state on the drawings or in a generally using state of the socket of this kind.

With reference toFIGS. 1to19, reference numeral11denotes an IC socket as “a socket for an electrical part”, which is a socket for establishing an electrical connection between a terminal12bin form of plate of an IC package12as “an electrical part” and a printed circuit board, not shown, of a measuring device such as tester, for carrying out a performance test of the IC package12.

The IC package12is so-called an LGA (Land Grid Array) type, such as shown inFIGS. 19A, B, and C, in which terminals12beach in shape of plate are arranged in rows to a lower surface of a square package body12aof the IC package12. A die12cis formed to the central portion of the upper surface of the package body12aso as to protrude upward as shown in FIG.19B.

On the other hand, as shown inFIG. 3, the IC socket11has a socket body13arranged on a printed circuit board, not shown, and this socket body13has a base portion15to which a number of contact pins14, contacting the terminals12bof the IC package12are disposed and a floating plate16disposed on the upper side of the base portion15.

A pair of open/close members19for pressing the IC package12are disposed to the socket body13to be rotatable, i.e. pivotal, and an operation member20in form of square frame is also provided for the socket body13to be vertically movable so as to open or close the open/close members19.

More in detail, each of the contact pins14is formed from a plate member having a springy property and an excellent conductivity as shown inFIGS. 8 and 9. The contact pin14is fitted and secured to a press-in hole15aformed to the base portion15of the socket body13, and the contact pin14has a lead portion14awhich extends downward from the base portion15so as to be electrically connected to the printed circuit board. The contact pin14is also provided with an elastic (resilient) portion14bformed on the upper side of the lead portion14a. The elastic portion14bhas approximately S-shape and elastically deformable property. A contact portion14cis further formed to an upper end portion of the elastic portion14bso as to abut against the IC package terminal12bfrom the lower side thereof to establish an electrical connection therebetween.

The contact pin14is inserted through a through hole16aof the floating plate16.

Further, it is to be noted that the term “contact pin” and the term “terminal” are used herein at almost all portions equivalently to “contact pins” and “terminals”.

This floating plate16has a rectangular shape in an outer appearance, as shown inFIG. 1, and has a accommodation surface portion16don which the IC package12is held and accommodated to be vertically movable with respect to the base portion15of the socket body13.

Guide portions16bfor guiding the IC package12at the accommodation time thereof are formed to the floating plate16at portions corresponding to corner portions of the rectangular package body12a. There are also formed projections16cfor mounting the IC package12at six positions so as to support the IC package through abutment against a peripheral edge portion of the package body12aat an area to which a number of through holes16aare formed in shape of matrix (seeFIGS. 1,8and9).

Furthermore, the floating plate16is disposed to be vertically movable with respect to the base portion15, and as shown inFIG. 7, is urged upward by means of spring17and stopped at a top dead center or position by a stopper portion15b(FIG. 5) formed to the base portion15so as to extend upward. The stopper portion15babuts against the upper surface of a guide portion16bof the floating plate16.

The guide portion16bis a portion for guiding the IC package12at the accommodating operation thereof, the guide portion16bbeing formed at a portion corresponding to each corner portion of the package body12a. Furthermore, as shown inFIG. 1,8or9, there are also formed projections16cfor mounting the IC package12at six positions so as to support the IC package through the abutment against a peripheral edge portion of the package body12aat a forming area of a number of through holes16aformed in shape of matrix.

FIG. 8shows the non-accommodation state of the IC package12andFIG. 9shows the accommodation state thereof. The contact pin14is disposed throughout the through hole16aof the floating plate16so that the contact portion14cthereof projects upward over the through hole16airrespective of accommodated state or non-accommodated state of the IC package12onto the accommodation surface portion16d.

In the non-accommodated state of the IC package12, that is, in the top dead center of the floating plate16, as shown inFIG. 8, a projecting distance H2of the mount projection16cfrom the accommodation surface portion16dof the floating plate16is made to be larger than a projecting distance H1of the contact portion14cof the contact pin14from the through hole16aof the floating plate16. Thus, at the top dead center, the contact portion14cof the contact pin14does not contact the terminal12bof the IC package12in the state that the IC package12is mounted on the mount projections16cof the floating plate16. When the floating plate16is depressed downward from the top dead center, the contact portion14cof the contact pin14contacts the terminal12bof the IC package12as shown inFIG. 9at a predetermined contacting pressure.

Further, a pair of open/close members19are disposed to be rotatable (i.e. pivotal) in both-side openable manner as shown inFIG. 5, each of the open/close members19has a base plate22to which a heat sink23as a pressing portion or member is formed, which is supported by the socket body13through a link mechanism27in a manner such that the heat sink23is displaced from the pressing position at which it presses the IC package12to its retiring or retired position.

More specifically, the heat sink23is made from an aluminum die-cast having a good heat conductivity, and as shown inFIGS. 1,10and11, the heat sink23has one side surface (lower side surface) to which an abutting projection23ais formed so as to abut against the IC package12and the other side surface (upper side surface) to which a number of radiation fins23bare formed for effective heat radiation.

The heat sink23is mounted to the base plate22to be movable in parallel in a perpendicular direction with respect to a plane (flat) surface22aof the base plate22under the guidance of four mounting screws29screwed with the base plate22, and the heat sink23is urged in a direction abutting the base plate flat surface portion22aby means of coil springs30each disposed around the mounting screw29.

The link mechanism27includes a pair of first link including first link outside member24and a first link inside member25and a second link26disposed on both sides of the base plate22, respectively.

The first link outside member24and the first link inside member25are formed so as to provide plate shapes as shown inFIGS. 12(12A,12B,12C) andFIGS. 13(13A,13B,13C), respectively, and as shown, one end portions24aand25aof these members are supported to a support post15cprojecting from the base portion15of the socket body13through a support shaft or pin32to be vertically rotatable. Further, it is to be noted that the first link outside member24and the first link inside member25are disposed on both sides of the base plate22to be symmetric with each other and only one of them is shown inFIGS. 12 and 13.

Furthermore, as shown inFIGS. 2 and 3, the other end portions24band25bor near of the first link outside member24and first link inside member25are attached to a perpendicular piece22bof the base plate22to be rotatable through a mount shaft33. Further, the first link inside member25is fanned with a crooked engaging piece25c to be engageable with a perpendicular piece22bof the base plate22as shown in FIG.1. According to this engagement, the base plate22is prevented from being rotated or pivoted in one direction about the mount shaft33with respect to the first link outside member24and the first link inside member25.

Still furthermore, as shown inFIGS. 14(14A,14B,14C), the second link member26is provided with a pair of side plate portions26adisposed on both sides of the heat sink23and a connection bridge portion26bin form of long scale plate. These side plate portions26aare disposed in a clamped state between the first link outside and inside members24and25to thereby keep the parallel arrangement of these members24and25with a predetermined interval.

The one end26cof the side plate portion26ais mounted, to be rotatable, to the operation member20through a power point shaft36, and the other end26dof the side plate portion26aand the other ends24band25bof the first link outside and inside members24and25are coupled to be rotatable to each other through the coupling shaft34.

According to the structure mentioned above, when the operation member20is lowered, in the manner shown inFIG. 5, from the top dead center shown inFIG. 3, the position of the power point shaft36is lowered and the lower edge recess26eof the side plate portion26aof the second link26abuts against the support shaft32. Then, the coupling shaft34as point of action is rotated upward with the support shaft32being fulcrum of lever, whereby the first link outside member24and the first link inside member25are rotated upward with the support shaft32being the center thereof, thus, the base plate22and the heat sink23are thereby opened upward.

On the other hand, the operation member20has, as shown inFIG. 15, a rectangular frame shape having a large opening20athrough which the IC package12can be inserted, and the operation member20is disposed to be vertically movable with respect to the socket body13.

That is, as shown inFIG. 3, the screw portions38aof the four guide pins38are screwed and fastened to the nuts39provided for the socket body13, and by inserting these guide pins38into the guide holes20bformed to the operation member20, the operation member20is guided by the guide pins38to be vertically movable. The operation member20is then urged upward by the coil springs41disposed around the guide pins38, respectively, and when moved to the top dead center, the peripheral edge portion20cof the guide hole20bof the operation member20abuts against the upper end flanged portion38bof each guide pin38to thereby prescribe the upward movement of the operation member20.

The guide hole20bof the operation member20is designed such that it is formed to the bottom surface of its recessed portion20dopened upward for the guide pin38, and when the operation member20is positioned at its top dead center, the upper end flanged portion38bof the guide pin38is positioned lower than the upper surface portion of the operation member20by a distance L1as shown in FIG.3.

Furthermore, an approximately circular ring shape recessed portion20copened downward for the spring41is formed around the recessed portion20dfor the guide pin38so that the upper end side of the coil spring41is fitted into this recessed portion20c. At the top dead center of the operation member20, the upper end of the coil spring41is positioned higher than the upper end flanged portion38bof the guide pin38as shown in FIG.3.

Still furthermore, the operation member20is, as shown inFIGS. 2 and 16, provided, at its opposing side portions20j, with two ventilation passages20f, respectively. The paired ventilation passages20fof each side portion20jof the operation member20are formed between the paired recessed portions20dfor the guide pins38in the horizontal direction as viewed in such a manner that an outside opening20gis formed on the outer edge side of the side portion20jand an inside opening20his formed on the inner edge side of the side portion20j. Each of the outer side openings20ghas a width W1 wider than a width W2 of each of the inner side openings20h.

According to such structure as mentioned above, when the open/close member19is in the closed state, outside air invading through the outside openings20gof the ventilation passages20fflows inside the operation member20and then towards the frame-shape heat sink23disposed inside to thereby be exhausted from the inside towards the outside thereof.

The IC package12is held and accommodated in the IC socket11of the structure mentioned above according to the following manner.

First, the operation member20is depressed by, for example, an automatic machine, against the urging force of the spring41. According to this motion, the power point shaft36of the operation member20is lowered and the second link26is rotated downward, and then, the lower end edge recessed portion26eof the second link26abuts against the support shaft32as shown in FIG.4.

When the operation member20is further depressed from this state, the second link26is rotated (pivoted) in accordance with the lever's theory about its support shaft32, the coupling shaft side is moved upward, the first link outside member24and the first link inside member25are rotated upward about the support shaft32, and the base plate22and the heat sink23are lifted upward through the mount shaft33, thus being opened as shown in the state of FIG.5.

At this operation, the depressing force to the operation member20is a sum of depressing force to the coil spring41and the weight of the heat sink23and others. Accordingly, there is no need of additional force against the urging force of the twist coil spring for ensuring the depressing force to the heat sink23, which is required for the conventional structure, thus easily opening the open/close member19with a reduced force.

Furthermore, since the base plate22and the heat sink23are supported to the mount shaft33and the engaging piece25cof the first link inside member25, the base plate22and the heat sink23can be prevented from being largely rotated or swung about the mount shaft33.

In the maximally opened state of the open/close member19, as shown inFIGS. 5 and 6, the open/close member19is positioned so as to extend along substantially perpendicular direction and retired from the insertion range of the IC package12.

Under such state, as shown inFIG. 8, the IC package12is guided on the floating plate16under the guidance of the respective guide portions16band rested on the mount projections16c. When mounted, the projecting amount (length) H2of the mount projection16cis larger than the projecting amount (length) H1of the contact portion14c, so that the terminal12bof the IC package12does not collide with the contact portion14cof the contact pin14, and hence, both are not damaged.

Furthermore, since the contact portion14cof the contact pin14always projects upward over the through hole16aof the floating plate16, no dust or like invades into the through hole16a, thus preventing the defective contact between the IC package terminal12band the contact portion14cof the contact pin14, and the smooth relative movement of the contact pin14with respect to the through hole16aof the floating plate16can be realized.

In the next stage, when the depressing force to the operation member20is released, the operation member is moved upward by the urging force of the coil spring41, and accordingly, the open/close member19is closed in the manner reverse to that mentioned above and the abutting portion23aof the heat sink23abuts against the die12cof the IC package12as shown in FIG.9.

In this operation, the base plate22is slightly rotated, i.e., pivoted, about the mount shaft33. Further, since the heat sink23is disposed to be vertically movable, with respect to the base plate22, by means of mounting screws29and the coil spring30, the package body12aof the IC package12can be finely angularly adjusted by the abutment of the abutting projection23aof the heat sink23at the time of depressing the package body12aof the IC package12. Thus, the force can be uniformly distributed under good balanced state.

Moreover, by lowering the floating plate16against the urging force of the spring17, the contact portion14cof the contact pin14largely projects over the through hole16aof the floating plate16and the contact portion14cabuts against the terminal12bof the IC package12as shown in FIG.9. Under such abutting state, the elastic portion14bof the contact pin14is elastically deformed, and according to this elastic force, a predetermined abutting force or pressure can be ensured. At this moment, as shown inFIG. 8, the contact portion side of the front side of the contact pin14and the lead portion14aof the root side thereof are positioned with a shifting of half pitch P, so that in the case where the front end of the contact portion14cis depressed downward, this front end does not fall and is displaced to a directly downward position, thus achieving the smooth displacement motion.

Furthermore, the location of the respective link members24,25and26makes it possible to ensure the contacting pressure of the contact portion14cof the contact pin14to the terminal12bof the IC package12without using a twist coil spring having a large urging force.

That is, as shown inFIG. 3, when a force F1is applied to the heat sink23towards the upward direction by the contact pin14and the floating plate16, this force F1acts on the coupling shaft34through the mount shaft33. Then, a component force F2of this force F1acts as a force to rotate the first link outside and inside members24and25about the support shaft32. However, in a case that it is attempted to rotate the first link outside and inside members24and25in the direction of the component force F2from the state shown inFIG. 3, the second link26will act as a strut member and, hence, another force F3for directing outward the power point shaft36is applied.

Further, although this force F3along the horizontal direction acts for outwardly deforming the operation member20, it does not act for lowering the operation member. Accordingly, since the second link26acts as a strut member without being rotated, the proper contacting pressure or force can be ensured between the terminal12bof the IC package12and the contact portion14cof the contact pin14.

Namely, the location of the link members24,25and26makes it possible to reduce the pressing force to the operation member20at the time of opening the open/close member19, and in addition thereto, the contacting pressure between the IC package terminal12band the contact portion14cof the contact pin14can be ensured even in the closing state of the open/close member19.

Furthermore, the second link26is, as shown inFIG. 1, composed of side plate portions26awhich are connected through a central bridging portion26b, and accordingly, even if a one-side pressing is applied to the operation member20, the laterally paired first link outside and inside members24and25are moved integrally, and the degree of the inclination of the base plate22due to such one-side pressing can be largely reduced.

Still furthermore, as shown inFIG. 5, the guide pins38can be made shorter, and accordingly, the upper end flanged portions38bof the guide pins38do not interfere with the heat sink23and other members and the IC socket12can be hence made compact, as shown inFIG. 5, even in the state that the operation member20is lowered and the open/close members19are rotated by about 90 degrees to its perpendicular state.

Still furthermore, as shown inFIG. 3, the coil spring41disposed around the thus shortly formed guide pin38is set to be long, so that the vertical stroke of the operation member20can be made longer, and according to the location of such coil spring41, upward urging force can be ensured in this long vertical stroke.

In addition, in a case of carrying out a burn-in test by setting an IC package12to such IC socket11, it is necessary to carry out the test under a predetermined temperature. However, in the accommodated condition of the IC package12, the periphery of the IC package12is covered by the frame shaped operation member20. Accordingly, even in a case that the heat is radiated through the heat sink23, in a conventional structure, heat inside the operation member20is difficult to be radiated, and hence, the inside portion is increased in temperature than the outside of the IC package12.

According to the present invention, on the other hand, since the two ventilation passages20fare formed to the side portions of the operation member20, the air circulates between the inside and outside portions of the operation member20through these ventilation passages20f. Thus, it becomes possible to examine the IC package12with a predetermined temperature condition.

Moreover, these ventilation passages20fare linearly formed, as shown inFIG. 16, to the opposed side portions.20jthereof, and accordingly, the air introduced inside the operation member20through the left side ventilation passage20f, for example, is subjected to heat exchanging operation at the IC package accommodated portion and then exhausted outside the IC socket11through the right side ventilation passage20f. Accordingly, such good ventilation permits the effective heat radiation of the IC package12.

Further, it is to be noted that, in the described embodiment, although the present invention is applied to an IC socket as “socket for electrical parts”, the present invention is not limited to such socket and is applicable to other devices or like.