WO2000067540A1

WO2000067540A1 - Chip carrier socket

Info

Publication number: WO2000067540A1
Application number: PCT/US2000/012108
Authority: WO
Inventors: William J. Hayes; Gary Held; Lee E. Palmer; Craig Reske
Original assignee: Wells-Cti, Inc.
Priority date: 1999-05-04
Filing date: 2000-05-04
Publication date: 2000-11-09
Also published as: AU4503000A

Abstract

A chip carrier socket (2, 202) for burn-in applications of integrated circuit chips includes a housing (4, 404) having a chip carrier nest (50, 450) and a rotatable cover (6, 206, 306, 506) which is hinged upon one side of the housing and rotatably movable into a latched position to hold the chip carrier in place. Electrical contacts (16) extend between the housing lower surface and the chip carrier nest to interconnect traces on a circuit board with the pads on the integrated circuit chip. The housing includes four corner posts (70, 600) having a spring loaded wire bar (110) extending between two of the posts, where the cover rotates about one of the bars and the latch engages the other bar. This arrangement permits relative movement between the cover and the nest. Moveable positioning members may be included to position the chip carrier in the nest. Preferably the cover is comprised of a thermally conductive material and has a contact engaging surface for abutment with the chip to be tested to remove heat from the integrated circuit chip.

Description

CHIP CARRIER SOCKET

This invention relates to an improved chip carrier socket, and in particular, to one for burn-in applications. Integrated circuits, or chips, must be tested after their manufacture, normally at elevated temperatures, which is the so-called burn-in process. The integrated circuits are temporarily installed on a circuit board, tested, and then removed from the circuit board and shipped. Accordingly, sockets are necessary to install the integrated circuits on the printed circuit board for testing. These sockets must include multiple contacts to connect each of the terminals of the integrated circuit chip to corresponding conductors in the circuit board. Since the sockets are used repeatedly in high volume integrated circuit chip manufacture, it is desirable that the sockets be durable and capable of reliable, repeated operation.

These sockets are positioned on a burn-in board where the sockets are arranged in a relatively dense array, to allow for as many integrated circuits as possible to be burned in at once. These sockets are therefore arranged in relatively close side-by-side and end-to-end spacing. This oftentimes makes the operation of the burn-in process more difficult, because the operator must be able to physically reach the sockets to open and close them.

It is also desirable that the chip carrier sockets be capable of conforming to a large tolerance of chip thicknesses. It is now commonplace where chip manufacturing results in a large tolerance of chip thickness, for example, some chips are nominally .042 inches thick, but can have a tolerance of + or - .003 inches of thickness. One of the socket types which perform this burn- in function is comprised of a base portion and a cover member which rotates about one side edge by way of a hinge, and a latch member which holds the cover and base together, where the latch is opposite the hinge side. The large tolerance in chip thicknesses causes great disparity in contact pressure between the contacts of the socket and the contact sections of the chip. For example, if the chip is on the high tolerance side, then the cover member causes greater pressure on the contacts which are proximate the hinge side, and lesser contact pressure adjacent to the latch side. The opposite phenomenon occurs when the chip is on the lower tolerance side.

It is desirable to equalize the contact pressure for a number of reasons. First, there should be good contact between the contacts of the socket and the chip to simulate actual working conditions. Secondly over time, with such large tolerances, the socket contacts can become over stressed to the point where the contact pressure is very light, and could result in a failed chip test even though the chip actually functions properly.

It is also critical in such applications to remove heat from the chip as quickly as possible, so that the chip does not fail during the test due to overheating. This requires that some sort of heat sink, or other heat removal mechanism be applied to the socket to accomplish this function.

The chips themselves are comprised of a silicon wafer or die, the back side of which is contacted for heat removal. Normally, a thermal compliant pad is positioned intermediate the die and the heat sink to improve the heat transfer between the chip and the heat sink. In today's market place, it is not uncommon to test integrated circuit chips during burn-in where the chips operate at speeds up to 1,000 MHZ. With such a rapidly operating integrated circuit chip, the heat load placed on the heat sink alone can cause the temperature of the integrated circuit chip to rise to the point where the chip is damaged if heat is not removed quickly enough. Thus, it is desirable to provide a socket designed for burn-in testing and operation of an integrated circuit chip operating at such high speeds. While the thermal compliant pad operates well for its intended function, the constant cycling of the pressure against the pad causes a secretion of the oil from within the pad. This oil can degrade the cleanliness of the test area, but also adds oily substance to the customer's chips, making them hard to print on, for example with a model number and date. It would therefore be desirable to have the thermal compliant pad be replaceable. The pad cannot be replaced on the board, as the pad would need to be scraped off, which could add dirt and residue to the socket contact areas.

U.S. Patent No. 4,758,176 shows a chip carrier socket having a housing, a chip receiving nest, a plurality of electrical contacts to interconnect the chip with a printed circuit board, and a latch member to hold the cover in place and the chip in electrical connection with the printed circuit board. U.S. Patent No. 4,758,176, while showing a portion of the housing which is pivotally moveable, the device cannot accommodate chips of various thicknesses.

The problem to be solved is to provide a chip carrier socket, whereby the tolerance on the chip can be in the range of plus or minus ten percent (10%) of nominal thickness, and whereby the chip's carrier socket can accommodate the variance in thickness, without any detriment to the electrical interconnection between the chip and the printed circuit board.

This problem has been solved by the invention of claim 1, where a chip carrier socket is provided having a housing having a first surface, a nest for receiving a chip carrier and a cover. The nest has a second surface substantially parallel to the first surface and a plurality of contacts. The cover is movable between open and closed positions and is attached to the housing so as to permit relative movement between the cover and the nest.

In a preferred embodiment of the invention, the cover is movable perpendicular to the second surface. The cover may be attached to the housing by a hinge that is moveable perpendicular to the second surface. A latch may also be provided. The latch may be moveable perpendicular to the second surface as well. The latch may include a tusk-shaped locking jaw.

In another embodiment of the invention, a chip carrier socket includes a housing having a first surface for contacting a circuit board, a nest for receiving a chip carrier, a plurality of contacts, a cover and a hinge connecting the cover to the housing. A portion of the hinge is moveable perpendicular to the first surface.

According to another embodiment of the invention, a chip carrier socket includes a housing having a first surface for contacting a circuit board, a nest for receiving a chip carrier, a plurality of contacts, a cover connected to the housing, the cover being moveable between an open position and a closed position, and a latch for securing the cover in the closed position, the latch being moveable perpendicular to the first surface.

In another embodiment of the invention, a chip carrier socket has a housing, a nest, an array of contacts and a cover moveable between an open position and a closed position. The cover has four corners, each of which is moveable perpendicular to the nest when the cover is in the closed position.

In another embodiment of the invention, a chip carrier socket includes a housing having a nest for receiving a chip carrier, a plurality of contacts and a cover moveable between open and closed positions. The cover has a first portion fixed to the housing and a second portion removable from the first portion. The first portion includes a surface for pressing the chip carrier into electrical contact with the contacts when the cover is in the closed position and the second portion includes a heat sink.

In yet another embodiment of the invention, a chip carrier socket includes a housing, a nest for receiving a chip carrier, a plurality of contacts and a moveable positioning member for positioning a chip carrier in the nest. Other features of the present invention will be apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiments and the accompanying drawings, whereby: Figure 1 is a perspective view of a chip carrier socket according to one embodiment of the invention.

Figure 2 is a view similar to that of Figure 1 , showing the cover of the chip carrier socket in a fully opened position. Figure 3 is a cross sectional view taken through line 3-3 of Figure 1.

Figure 4 is a longitudinal cross sectional view of a post that is a component of the chip carrier socket shown in Figure 1.

Figure 5 is an alternative embodiment of the post as shown in Figure 4.

Figure 6 is a perspective view of an alternative embodiment of a chip carrier socket according to the present invention.

Figures 7-9 are perspective views of the parts of the cover that is a component of the embodiment shown in Figure 6.

Figure 10 is a view similar to that of Figure 6, showing the cover of the chip carrier socket closed and latched. Figure 11 is a view similar to that of Figures 6 and 10 , showing the cover of the chip carrier socket opened.

Figure 12 is a perspective view of an alternative embodiment of a cover.

Figures 13-18 are perspective views of the components of the cover shown in Figure 12.

Figure 19 is a perspective view of an alternative embodiment of a chip carrier socket in accordance with the present invention.

Figure 20 is a perspective view of the housing of the device shown in Figure 19.

Figure 21 is a perspective view of a positioning member that forms a component of the device shown in Figure 19.

Figure 22 is perspective view of an alternative embodiment of a chip carrier socket in accordance with the present invention with the cover in the open position.

Figure 23 is a perspective view of the device shown in Figure 22 with the cover in the closed and latched position.

Figure 24 is a perspective view of a latching arm that is a component of the device shown in Figure 22. Figure 25 is a cross-sectional view taken along line 25-25 in Figure 22. With respect to Figure 1 , a chip carrier socket in accordance with the present invention is shown generally as reference numeral 2 which includes a housing 4 and a cover 6. The socket

2 shown in Figure 1 is intended to house an integrated circuit chip for testing, in this case, a Land

Grid Array (LGA) chip, having a plurality of contact pads on one side thereof. With respect to Figures 2-4, housing 4 will be described in greater detail.

The housing 4 in accordance with an embodiment of the invention is preferably manufactured from an insulative material, and in the embodiment shown, is comprised of a first housing member 10, a second housing member 12, and a third housing member 14 located intermediate housing members 10 and 12. A plurality of electrical contacts 16 extend between first and second housing members 10 and 12 to make electrical contact between the pads of a circuit chip and the circuit traces on a printed circuit board, as will be described in greater detail. With reference still to Figure 3, the first housing member 10 includes a first surface 18 for contacting a printed circuit board. At least one locating post 22 extends from surface 18. The first housing member 10 further includes a second surface 24 having a recessed pocket 26 for receiving the third housing member 14. The first housing member 10 includes a wall 28 having a plurality of apertures 30 extending therethrough for receipt of the contacts 16. With respect still to Figure 3, the third housing member 14 includes an outer periphery 32 which is profiled for receipt within the pocket 26 and includes a plurality of apertures 34 for alignment with the apertures 30 of the first housing member 10 for receipt of the contacts 16 therethrough. The second housing member 12 includes a first surface 40 having four walls 42, 44, 46 and 48. The second housing member 12 further includes a chip receiving nest area shown generally as 50 generally defined by four L-shaped corner members 52 and a surface 54 having a plurality of apertures 56 extending therethrough. Apertures 56 are in alignment with apertures 30 and 34 of housing members 10 and 14 such that contacts 16 may extend therethrough. It should be appreciated from Figure 3 that the contacts 16 have end sections which stand proud of surfaces 18 and 54 for respective contact with the printed circuit board and chip to be received in the nest 50. It should also be appreciated that the members 52 are so arranged to accommodate the correct chip sizing such that upon insertion of the chip in the nest 50 members 52 align contact pads on the chip with the contacts 16 extending through surface 54. It should also be noted from Figure 2 that housing members 10, 12 and 14 are held together by way of split arrow latch fingers 60 which extend upwardly from housing member 10 and are received in and latched to a surface 62. Other methods of securing housing members 10, 12 and 14 together may also be used. With reference now to Figures 2 and 4, a post 70 extends in each corner of the housing 4 and assists in retaining the cover 6 to the housing 4 as will be describe herein.

With reference to Figure 4, the post 70 includes a first portion 72 having an internal bore section 74 extending along the length thereof, which is continuous with a threaded bore section 76. The first portion 72 further includes a slot 78 extending therethrough, which communicates between the exterior of the first portion 72 and the bore 74. Post 70 further includes a second portion 80 having a threaded section 82, a first surface 84 and a shoulder 86 defined by an enlarged section 88. Section 90 of second portion 80 extends downwardly from the enlarged section 88 and extends proud of the surface 18 as shown in Figure 3. Second portion 80 further includes a threaded section 92 which engages corresponding threads within the housing 4 for a rigid connection thereto. With reference still to Figure 4, a spring 100 is located in the bore 74 of first portion 72 and spring loads a cylinder 104 downwardly into abutment with the surface 84. The cylinder 104 has an aperture 106 which at least on one side is in communication with slot 78. As shown in Figure 2, four posts 70 are positioned in corners of the housing 4 such that slots 78 are facing each other. Slots 78 receive bars 110 such that bars 1 10 may slide within slots 78 of each post 70 and into the apertures 106 of the cylinders 104. It should be understood that due to the spring 100, the cylinder 104, as well as the bar 110, are normally positioned as shown in Figure 4, that being the fully down position. While the posts 70 are shown herein as separate members, it is clear to those of ordinary skill in the art that the posts 70 could be integrated with the housing 4.

With respect again to Figure 2, the cover 6 is, in the embodiment shown, comprised of a thermally conductive material, such as aluminum, such that the cover is profiled for abutment directly against the back side of the chip die to provide heat transfer between the integrated circuit chip and the cover 6. To that end, the cover 6 includes a body 120 having a lower surface

122 having a contact surface 124 extending therefrom. The body 120 further includes an upper surface 126 having a plurality of fin members 128 extending therefrom, to provide the heat transfer function, as is well known in the art.

With respect now to Figure 3, body 120 includes at the front side thereof, a front nose section 130 extending forward from a front edge 132 (Figure 2) of the body 120. With reference now to Figures 2 and 3, the latch 140 will be described, which, in the embodiment shown, is comprised of the latching arm 142 together with the lock release member 144. As shown best in Figure 3, the lock release member 144 includes arms 146 which flank the nose member 130 and are pinned thereto by way of a pin 150 and appropriate apertures through the nose member 130 and arms 146. Meanwhile, the latching arm 142 includes a lower locking jaw 152 and upstanding arms 154 which are pinned to the arms 146 of the lock release member 144 at 160 as shown in either of Figures 2 or 3.

With respect still to Figures 2 and 3, the body 120 includes at the rear side thereof, mounting leg portions 164 which extend downwardly from the body 120 to define a recessed surface 166 and sidewall surfaces 168. A bar 1 10, identical to the bar 1 10 at the forward side thereof, extends through two rear posts 70. through apertures in the leg portion 164, and through a torsion spring member 170 to hold the cover 6 in the open position of Figure 2. In this manner, post 70, bar 1 10 and leg portions 164 act as a hinge to allow cover 6 to pivot. Note that each end of this hinge, i.e., the opposite ends of bar 1 10, can each move vertically independent on one another. In this manner, a vertically movable hinge is provided which allows the hinge and the rear end of cover 6 to move peφendicularly with respect to surface 18. With the design as described above, the operation of the chip carrier socket will now be described in detail. With reference first to Figure 2, a chip to be inserted into the chip carrier socket 2 will be positioned between the four L-shaped members 52 to position the pads on the integrated circuit chip in alignment with the contacts 16 of the socket. The cover 6 can now be rotated in the clockwise direction, as viewed in Figure 2, to a position where the latching arm 142 approaches the bar 110. It should be appreciated that due to the over-center nature of the pinning between the latching arm 142 and the release member 144, that by moving the release member 144 clockwise, or forward, that the locking jaw 152 will be lowered, so as to be receivable under the bar 110 at the forward side thereof. To fully lock the cover 6 in place, the release member 144 is now rotated in the counter-clockwise direction, into the position shown in Figure 3 , which pulls the locking jaw 152 upwardly in the vertical sense beneath the bar 110. Note that, as with bar 110 at the opposite end of cover 6, the bar 110 engaged by latch 140 can move peφendicularly with respect to surface 18. Additionally, each end of bar 110 may move peφendicularly independent of the other. Thus, a latch is provided which can move peφendicularly with respect to surface 18. This allows the front portion of cover 6 to move peφendicularly as well. Similarly, each corner of cover 6 can move peφendicularly with respect to surface 18 independently of the other corners, thereby permitting cover 6 to "float" and accommodate chips of varying thicknesses. Viewed another way, nest 50 can be considered to float or move relative to cover 6.

It should be appreciated from the Figure 3 configuration that the distance between surface 54 and surface 124 is less than the smallest possible thickness of a chip to be tested. Thus when an integrated circuit chip is placed in the socket, and the latch is placed in the position shown in

Figure 3, there will be a contact pressure between the contact pads of the integrated circuit chip and the contacts 16. By allowing the cover to move vertically upwardly, and to pivot or tip, the cover 6 can accommodate various thicknesses of chips, and can adapt to the thicknesses to more evenly distribute the contact pressure which is exerted on the various pad locations. Another embodiment of the invention is shown in Figure 5, where the spring load within each post 70 is independently variable. In this version, a set screw 200 is added to the tip of first portion 72, which can be inserted into or withdrawn from the bore 74, which will change the prestress on the spring 100.

With respect now to Figures 6-11 , a further embodiment of the invention will be shown, and will be referred to generally by the reference numeral 202. It should be appreciated that in this embodiment, the housing is identical to housing 4, as described with reference to Figures 1 -4, and therefore will not be repeated here. What is different about embodiment 202 is the cover

206.

With reference first to Figure 6, the cover will be described. Cover 206 includes a first removable portion 208 joined to a second fixed portion 210. The assembly further includes a latch 240 having a latching arm 242 and a lock release member 244. These features and their associated operation will now be described in greater detail below.

As shown in Figures 7 and 8, the first portion 208 includes underside 222 having a pressure surface 224. It is this pressure surface 224 to which the compliant pad is normally bonded. The first portion 208 further includes an upper surface 226 having a plurality of fins

228. As best shown in Figure 7, the fins 228 are transversely interrupted by a pair of slots at 229, which will be described in greater detail herein.

As also shown in Figure 7, the first portion 208 further comprises a nose section 230 extending forwardly from a front end section 232. The first portion 208 also includes mounting tabs at 234, both of which have an aperture extending therethrough.

With reference now to Figure 6, the latch 240 will be described in greater detail. The lock release member 244 includes two arm portions 246 which flank the nose section 230 and are pinned to the nose section at 248. The latching arm 242 includes a lower locking jaw at 252, which is profiled for gripping engagement beneath bar 1 10, as previously described. The latching arm 242 further includes two upstanding arm portions 254, which are pinned to the arm portions 246, at 260. It should be appreciated that the pinned locations 248 and 260 are spaced apart by a radial distance, which accounts for a pivotal and vertical movement of the locking jaw 252, as will be described herein. As best shown in Figure 6, a mechanical advantage member is included, which is comprised of a handle 270 and two rods 272 which extend from the handle 270 and into the arms 246.

Finally, with respect to Figure 9, the second portion 210 of the cover 206 will be described. Second portion 210 includes mounting surfaces 280 having threaded apertures 282 extending therein. A transverse bar section 284 rigidifies the assembly. Second portion 210 is secured to first portion 208 by positioning surfaces 280 and 235 such that apertures 236 and 282 are aligned. Capscrews 284 (see Figure 6) are then used to secure the two members together. The cover 206 is rotatably secured to the housing 4 as described with relation to the embodiment of Figures 1-4, that is, with a bar 110 (Figure 2) extending through aperture 288 (Figure 9) of second portion 210 and into slots 78.

Now with reference to Figure 6. the operation of the latch assembly will be described. It should be appreciated that the mechanical advantage member comprised of the handle 270 and rods 272 allows for the easy rotation of the lock release member 244. For example, when an integrated circuit is to be tested, the cover 206 is rotated open sufficiently to allow the chip to be placed in the nest as described above. The cover 206 is then rotated to a position similar to that shown in Figure 6. Handle 270 is then rotated, thereby causing the rotation of the lock release member 244 about its pinned location 248. This lowers the latching arm 242, to a position where the locking jaw 252 is at a position vertically lower than the associated bar 110. At this point, the continued rotation of the handle 270. causes contact between the arm sections 246 and extension sections 255 of the latching arm 242, which causes the latching arm 242 to rotate beneath bar 110. Prior to this engagement, the latching arm 242 simply hangs naturally by gravity, pinned at 260.

It should be understood at this point, that the handle 270 can be rotated in the opposite sense, which causes the engagement between the jaw 252 and the bar 110, and further rotation of the handle causes the continued lowering of the cover 206. In the fully closed position, the rods 272 will lie in the associated transverse grooves 229, as best shown in Figure 10. With respect now to Figures 12- 18, a further embodiment of the cover will be described. As shown in Figure 12, the cover 306 includes a first removable, two-part portion 308 and a second fixed portion 310. It should be understood that the portion 308 is removable in the same manner that portion 208 is removable from the portion 210 shown in Figure 6. It should also be appreciated that a latching assembly such as 240 is positionable on the nose portion 330 of the cover 306, in a similar manner as described with reference to Figure 6. This latch assembly moves between open and closed positions bringing the chip and cover 306 into contact with rods 272 located in slots 329 extending through the fins 328.

As shown in Figure 13, first portion 308 includes an upper member 308a having a rectangular plate portion 320 having a plurality of fins 328 extending upwardly therefrom, mounting legs 334 having apertures 336 extending from the rear of the plate portion 320, and mounting ears 338 extending from side edges of the plate portion 320 having apertures 340 extending therethrough. As mentioned prior, the nose 330 extends forwardly from the horizontal plate portion 320. With respect now to Figure 14, the underside of member 308a includes an underside surface 342 having a rectangular pocket 344 recessed into the surface 342, as will be described in greater detail.

With respect now to Figure 15, the cover 308 also includes a lower member 308b which, in the embodiment shown, includes a generally rectangular plate portion 346 having mounting ears 348 flanking side edges of the plate portion 346 and having threaded mounting apertures 350. The rectangular plate portion 346 further includes an upwardly facing surface 352 having a recessed pocket 354 extending therein which is complimentary to the recessed pocket 344 in the upper member 308a, as will be described in greater detail herein.

With reference now to Figure 16, the lower surface of member 308b is shown as including a pressure surface 364 which is analogous to the pressure surface 224 as shown in Figure 8. However, as shown in Figure 16, the surface 324 includes a notch or groove 366 as well as a thermistor 368 having leads 370 which are dressed within the groove 366 and extend rearwardly of the member 308b, and will be described in further detail herein.

With respect now to Figures 17 and 18, the third portion 310 of the cover 306 is attached to the housing 4 so as to be rotatable about the pivot points 388. As shown in Figures 17 and 18, the third portion 310 includes mounting portions 386, which fix third portion 310 to the housing

4 and includes upper mounting surfaces 380 having threaded apertures 382. The upper surface 380 includes recessed areas 384, 385. With respect now to Figure 12, the assembly of the cover 306 will be described in greater detail. As mentioned above, given the nature of the high speed integrated circuit chips which are now being tested, new sockets are required having auxiliary heat removal mechanisms other than traditional heat sinks and their associated fins. In this case, the auxiliary device is a thermoelectric cooler shown at 390, having leads 392 extending outwardly therefrom. While the thermoelectric cooler is not specifically shown, it should be understood that the cooler 390 is a semiconductor-based electronic device that operates in an analogous fashion to a heat pump. The thermoelectric cooler operates on a low- voltage DC power source whereby heat is moved through the device from one side to the other. One of the sides of the device is cooled while the alternate side is heated. The sides which are heated and/or cooled can be reversible by changing the polarity of the DC power source. It should also be noted that the thermoelectric cooler is similar to that which is shown in U.S. Patent No. 5,064,476, which is incoφorated herein by reference.

In this specific application, the thermoelectric cooler 390, will have a semiconductor body portion which is sandwiched between the upper and lower members 308a and 308b, and will be positioned within the pocket portions 344 and 354. The thermistor 368, which is adj acent to the pressure surface 364, Figure 16, is proximate to the integrated circuit device which is being tested. It should be appreciated that the thermistor will monitor the localized temperature of the integrated circuit device being tested. In the case where the integrated circuit device becomes overheated, which temperature can be different for different devices, the thermoelectric cooler will be operated to move heat away from the integrated circuit device and the cover 306 operates to discharge the heat away. It should be appreciated from Figure 12 that the upper and lower members 308a and 308b are held together by fasteners through their associated mounting holes 340 and 350 to hold members 308a and 308b together, which in turn holds the thermoelectric cooler in its associated pockets 344 and 354. At the same time, the leads 370 from the thermistor 368 and the leads 392 from the thermoelectric cooler 390 can be dressed rearwardly through the recessed portion 385 of the second portion 310 and be connected to its associated control mechanism. In this manner, the device can be utilized for increased integrated circuit speeds and temperatures without damage to the chip or the circuitry to which it is connected.

Figures 19-22 shown an alternative embodiment of the chip carrier socket according to the present invention. In this embodiment, a plurality of positioning members 405 are disposed in housing 404 around nest area 450 as shown. In the embodiment shown, two positioning members 405 are placed on each side of nest 450. Each positioning member 405 generally includes a first end 405a and a second end 405b. A surface 405c is disposed adjacent end 405b and faces inwardly toward nest area 450. At the opposite end 405a, a slot or notch 405d is formed to receive a portion of a biasing member 405 e. In the embodiment shown, biasing member 405e is a coil spring secured in housing 404. The free ends of the coil spring extend upwardly behind surface 405c to bias members 405 inwardly toward nest area 450. The positioning members 405 are placed about nest area 450 such that the distance between the inward most portion of surfaces 405c of members 405 directly opposite one another is less than the width of the smallest chip carrier to be tested. Thus, when the chip carrier is inserted into the socket, it will ride against surfaces 405 c causing them to flex outwardly. However, the positioning of surfaces 405c will ensure that the chip carrier is appropriately centered in the nest area 450. Once the chip carrier is in place, the cover 206 is closed and latched as described above. As cover 206 is closed, it contacts surfaces 405c and causes them to flex outwardly, such that they do not interfere with the engagement between cover 206 and the chip carrier. Note that it is not necessary to use eight positioning members 405. Various numbers can be utilized to achieve the same result. It is also not necessary to have two separate members 405 on each side of nest 450. Rather, a single positioning member 405 could be utilized. Additionally, biasing member 405e need not be a coil spring. Various other devices, such as leaf springs, could likewise be utilized. Similarly, surfaces 405c can be shaped differently than illustrated. Other modifications will be apparent to those of ordinary skill in the art. Figures 22-24 show an alternative embodiment of a latch. Latch 540 includes a handle

570 with two rods 572 extending therefrom. Rods 572 are connected to latching arm 542 at 572a. A pair of locking jaws 552 extend from latching arm 542. Latching arm 542 is pinned to nose section 530 of cover 506 at locations 548. In this manner, latching arm 542 can pivot about location 548. Note that in this embodiment, rods 572 are connected directly to latching arm 542, which is integral with locking jaws 552. This differs from the embodiment of Figure 6, in which rods 272 are connected to arm portions 246 of lock release member 244, which is in turned pinned to latching arm 242.

Note that in this embodiment, locking jaws 552 are curved into a generally tusk-shaped member. Each locking jaw 552 includes a small hump or projecting surface 552a. In use, the leading edges 552b of locking jaws 552 are placed under bar 1 10. Handle 570 is then rotated backward. As this occurs, bar 110 rides along locking jaws 552 until it reaches projecting surface 552a. Further rotation of handle 570 causes bar 1 10 to rise up and over surface 552a until it clears surface 552a and locks into the position shown in Figure 23. This rotation of handle 570 and interaction of locking jaws 552 and bar 1 10 draw cover 506 downwardly and into position for use.

Figures 22, 23 and 25 show an alternative embodiment of a post 600. In this embodiment, a post 600 has a first unthreaded portion 601 and a second threaded portion 602 extending through cylinder 603 into housing 4. A bore 604 in housing 4 is threaded to receive portion 602. A spring 605 is disposed between cylinder 603 and head 606 of first portion 601.

An opening 607 is formed in head 606 to receive a tool. Note that spring 605 is loaded by adjustment of head 606 to compress spring 605 as desired. Bars 110 extend into openings 608 of cylinders 603. Note also that in this embodiment, cover 706 is a one-piece member. Cover

706 can be removed by removing the two rear posts 600 and the corresponding cylinders 603.

In this manner, cover 706 can be removed as a one-piece assembly.

Although the present invention has been shown and described in detail, the same is to be taken by way of example only and not by way of limitation. Numerous changes can be made to the embodiments described above without departing from the scope of the invention.

Accordingly, the scope of the present invention is to be limited only by the terms of the claims appended hereto.

Claims

What is claimed is:

1. A chip carrier socket (2, 202) including a housing (4, 404) having a first surface (18, 418), a nest (50, 450) for receiving a chip carrier, the nest having a second surface (54, 454) substantially parallel to the first surface, a plurality of contacts (16), a cover (6, 206, 306, 506) movable between open and closed positions, and a latch (140, 240, 540), the chip carrier socket being characterized in that the cover (6, 206, 306, 506) and/or the nest (50. 450) are moveable in a peφendicular direction relative to the first surface (18. 418).

2. The chip carrier socket of claim 1, characterized in that the cover (6, 206, 306, 506) is attached to the housing (4, 404) so as to be movable peφendicular to the second surface (54, 454).

3. The chip carrier socket of claim 1 or 2, characterized in that the cover (6, 206, 306, 506) is attached to the housing (4, 404) by a hinge (70, 88, 110; 70, 1 10, 288; 70, 110, 388; 600, 110, 588) and a portion of the hinge is movable peφendicular to the second surface (54, 454).

4. The chip carrier socket of claim 3 or 4, characterized in that the hinge (70, 88, 110; 70, 110, 288; 70, 110, 388; 600, 110, 588) includes a pair of posts (70. 600), an opening in the cover (88, 288, 388, 588) and a bar (110) extending through the opening (88, 288, 388, 588) and between the posts (70, 600).

5. The chip carrier socket of claim 4, characterized in that bar (110) is moveable peφendicular to the second surface (54, 454).

6. The chip carrier socket of claim 4, characterized in that the bar (110) is biased toward the first surface (18, 418).

7. The chip carrier socket of any of claims 4-6, characterized in that each post (70) includes an internal bore (74) and a cylinder (104) located within the bore (74), and wherein the bar (110) extends through an opening in each post (78) and into an opening ( 106) in each cylinder (84).

8. The chip carrier socket of claim 7. characterized in that each post (70) includes a spring (100) located within the bore (74) for biasing the cylinder (104) toward the first surface (18, 418) and a screw (200) for adjusting the biasing force of the spring (100).

9. The chip carrier socket of any of claims 5-7, characterized in that each post (70, 600) includes a cylinder (104, 603) having an opening (106, 608) for receiving the bar (110) and a spring (100, 605) for biasing the cylinder (104, 603) toward the first surface (18, 418).

10. The chip carrier socket any of claims 1 -9, characterized in that the latch ( 140, 240, 540) is movable peφendicular to the second surface (54, 454).

11. The chip carrier socket of any of claims 1-10, characterized in that the latch (140, 240, 540) engages a bar (110) extending between a pair of posts (70, 600) to secure the cover (6, 206, 306, 506) in the closed position.

12. The chip carrier socket of claim 11, characterized in that the bar (110) engaged by the latch (140, 240, 540) is moveable peφendicular to the second surface (54. 454).

13. The chip carrier socket of claim 11 , characterized in that each post (70) includes an internal bore (74) and a cylinder (104) located within the bore (74), and wherein the bar (110) engaged by the latch (140, 240, 540) extends through an opening (78) in each post (70) and into an opening (106) in each cylinder (104).

14. The chip carrier socket of claim 13, characterized in that each post (70) includes a spring (100) for biasing the cylinder (104) toward the second surface (54, 454) and a screw (200) for adjusting the biasing force of the spring (100).

15. The chip carrier socket of claim 11 or 12, characterized in that each post (70, 600) includes a cylinder (104, 603) having an opening (106, 607) for receiving the bar (1 10) engaged by the latch (140, 240, 540) and a spring (100. 605) for biasing the cylinder (104, 603) toward the second surface (54, 454).

16. The chip carrier socket of any of claims 1-15, characterized in that the latch (140, 240, 540) includes a locking jaw (152, 252, 552) pivotally attached to the cover (6, 206, 306, 506).

17. The chip carrier socket of any of claims 1-16, characterized in that the cover (6, 206, 306, 506) has four comers each of which is moveable perpendicular to the nest (50, 450) when the cover (6, 206, 306, 506) is in the closed position.

18. The chip carrier socket of claim 17, characterized in that the corners are biased toward the housing (4, 404) when the cover (6, 206, 306, 506) is in the closed position.

19. The chip carrier socket of any of claims 1-18, characterized in that the cover (306) has a first portion (310) fixed to the housing (4, 404) and a second portion (308) removable from the first portion (310).

20. The chip carrier socket of claim 19, characterized in that the second portion (308) includes a surface (364) for pressing the chip carrier into electrical contact with the contacts (16) when the cover (306) is in the closed position and the second portion (308) includes a heat sink.

21. The chip carrier socket of any of claim 1 -20, characterized in that a plurality of moveable positioning members (405) are disposed about the nest (450) for positioning a chip carrier in the nest (450).

22. The chip carrier socket of claim 21 , characterized in that the positioning members (405) are located so as to contact a chip carrier as the chip carrier is placed in the nest (450).

23. The chip carrier socket of either claim 21 or 22, characterized in that the positioning members (405) are located so as to contact a chip carrier in the nest (450) when the cover (6, 206, 306, 406) is in the open position.

24. The chip carrier socket of claim 22 or 23. characterized in that closing the cover (6, 206, 306, 506) causes the positioning members (405) to move so as to no longer be in contact with the chip carrier.

25. The chip carrier socket of any of claims 21-24, characterized in that a biasing member (405e) urges the positioning members (405) toward the nest (450).

26. A chip carrier socket including a housing (4, 404) having a first surface (18, 418), a nest (50, 450) for receiving a chip carrier, the nest having a second surface (54. 454) substantially parallel to the first surface, a plurality of contacts (16), a cover (506) movable between open and closed positions, and a latch (540), characterized in that latch (540) includes a pair of generally tusk-shaped locking jaws (552).