Abstract:
A socket is provided for burn-in testing of an integrated circuit package having electrical leads. The socket includes a socket body having an array of columns and rows of generally rectangular terminal-receiving cavities therein, each of the generally rectangular terminal-receiving cavities having a longitudinal direction corresponding to its longer dimension and a plurality of terminals disposed in the terminal-receiving cavities for contacting the leads of the integrated circuit package. Each column and row of the array includes a sequence of at least three adjacent cavities wherein for each cavity of the sequence other than the first and last, the longitudinal direction of the cavity is substantially perpendicular to the longitudinal direction of the two cavities in the sequence adjacent the cavity on either side.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to electrical connectors, and more particularly, to burn-in sockets suitable for the testing of integrated circuit (“IC”) packages. 
     Conventional burn-in sockets typically include a plurality of terminals fitted in a corresponding plurality of terminal-receiving cavities. The terminals generally include a contact section for contacting leads from the IC packages, tail sections for electrically connecting to another electronic component, and resilient sections between the contact sections and tail sections for providing contact pressure to ensure a reliable electrical path through the terminal. 
     Most commonly, terminal-receiving cavities are rectangular and uni-directionally aligned. Although there are examples of such rectangular cavities having been aligned obliquely or being haphazardly unaligned, they are typically uniformly aligned parallel or perpendicular with respect to the sides of the socket housing. 
     Regardless of the alignment, however, it is generally desirable, due to the increased miniaturization of electrical components and the increased demand for higher speed and parallel pathways, to increase the density of terminals through the socket. Thus, it is an object of the invention to provide a burn-in socket which permits an increased density of terminals per unit area in the socket body while maintaining sufficient strength to withstand the cycled stresses of repeated engagement and disengagement with IC packages being tested sequentially. 
     An additional factor relevant to the quality of sockets designed for burn-in testing of integrated circuit packages is the efficiency with which they can test such packages. Thus, it is important to ensure that integrated circuit packages inserted into burn-in sockets are properly aligned within the socket for testing. In particular, misaligned packages may provide faulty test readings as leads from the integrated circuit packages may not have reliable electrical pathways to the electrical testing component, such as a burn-in board. Conventional burn-in testing sockets which include apparatus for lowering an integrated circuit package into contact with the terminals thereof often have less than satisfactory means for assuring lateral position of the package and, thus, may produce unsatisfactory burn-in testing results and efficiency. 
     Accordingly, it is an object of the present invention to provide a burn-in socket capable of permitting the residence of terminals therein at an increased density without harming the physical strength and performance of the socket. It is another object of the present invention to assure that each terminal has reliable contact with an appropriate lead of an inserted integrated circuit package to provide more efficient burn-in testing of integrated circuit packages. 
     SUMMARY OF THE INVENTION 
     To attain the aforementioned objects, a socket is provided for burn-in testing of an integrated circuit package having electrical leads. In one embodiment of the invention, the socket includes an outer socket housing and an inner socket housing slidably moveable relative to the outer housing between an upper limit position and a lower limit position, the inner housing for supporting the integrated circuit package thereon and having a plurality of terminal-receiving cavities therein. The socket further includes a plurality of terminals disposed in the terminal-receiving cavities of the inner housing for contacting the leads of the integrated circuit package, a cam mechanism for raising and lowering the inner housing between the upper limit position and lower limit position relative to the outer housing, and a latch mechanism for holding and releasing the integrated circuit package relative to the inner housing. 
     In another aspect, the socket of the invention includes an opening for insertion of the IC package, an outer socket housing, and an inner socket housing that is slidable relative to the outer housing between an upper limit position and a lower limit position. The inner housing has a plurality of terminal-receiving cavities therein, a plurality of terminals disposed in the terminal-receiving cavities of the inner housing, a cam mechanism having an actuator, and a latch mechanism having the same actuator as the cam mechanism. At least one of the cam mechanism and the latch mechanism includes a return biasing apparatus, and the latch mechanism includes a latch arm. 
     The unique lattice arrangement of terminal-receiving cavities and terminals permits increased terminal density without compromising the strength and physical performance characteristic of the test socket. Furthermore, the unique interaction of the cam mechanism and latch mechanism relative to the timing of the insertion/removal of the integrated circuit and the relative gentle and steep sloped portions of the interaction between the cam surface and cam follower surface provide a reliable socket and method for burn-in testing of integrated circuits, wherein the risk of fallen or dislocated integrated circuits is minimized. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a burn-in socket constructed in accordance with the principles of the present invention; 
     FIG. 2 is a side elevational view of the burn-in socket of FIG. 1 taken in the direction indicated by arrow P as shown in FIG. 1; 
     FIG. 3 is a side-elevational side view of the burn-in socket of FIG. 1 taken in from the direction indicated by arrow Q in FIG. 1; 
     FIG. 4 is a sectional view of the burn-in socket of FIG. 1 taken along line  4 — 4  thereof, showing the relative disposition of the components of the burn-in socket when an IC package is subjected to a burn-in test; 
     FIG. 5 is a partial sectional view, similar to that of FIG. 4, showing other components of the burn-in socket when an IC package is in place therein; 
     FIG. 6 is a partial sectional view of the burn-in socket of FIG. 1, taken along the line  6 — 6  in FIG. 1, also showing other components of the socket when an IC package is in place therein; 
     FIG. 7 is a partial sectional view of the burn-in socket of FIG. 1 taken along line  4 — 4  thereof, showing components of the socket when the socket is in an intermediate state prior to full insertion of the IC package therein; 
     FIG. 8 is a partial sectional view of the burn-in socket of FIG. 1, taken along line  6 — 6  thereof, showing how often components of the burn-in socket are disposed when the burn-in socket is in the same state as shown in FIG. 7; 
     FIG. 9 is a partial sectional view of the burn-in socket of FIG. 1, taken along line  4 — 4  thereof, showing specific components of the burn-in socket in place when either the IC package has been released after a test or when the IC package is initially placed into the burn-in socket; 
     FIG. 10 is a partial sectional view of the burn-in socket of FIG. 1, taken along line  6 — 6  thereof, showing there components of the burn-in socket in the same state as in FIG. 9; 
     FIG. 11 is a schematic plan view representation of a lattice of terminal-receiving cavities arranged in the test socket of FIG. 1; 
     FIG. 12 is an enlarged, more detailed view of a portion of the lattice of FIG. 11 at the location indicated by arrow A in FIG. 1; 
     FIG. 13 is a side elevational view of a terminal constructed in accordance with the principles of the present invention; 
     FIG. 14 is an end elevational view of the terminal of FIG. 13; 
     FIG. 15 is an enlarged, detailed sectional view taken at arrow B of FIG. 4 illustrating how the contact sections of selected terminals in contact with solder balls of the IC package; 
     FIG. 16 is a plan view of a pivoting latch piece used with the burn-in socket of FIG. 1; 
     FIG. 17 is a side elevational view of a latch piece of FIG. 16; 
     FIG. 18 is a partial sectional side view of a top cover used with the burn-in socket of FIG. 1; and, 
     FIG. 19 is another partial sectional side view of a top cover. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a burn-in socket  1  can be seen to include a socket body  2 , which, in turn, includes an outer housing  3  having attached pegs  3   a  integrally connected to its bottom, and an inner housing  4  fitted in the outer housing  3 . Specifically, the inner housing  4  is fitted in the outer housing  3  with the engagement nails  6  of the inner housing  4  coming flush with counter-engagement nails  5  of the outer housing  3  to prevent the inner housing  4  from separating from the outer housing  3  while permitting the inner housing  4  to descend into the outer housing  3 . 
     The inner housing  4  has a recess  4   b  on its top  4   a,  and a plurality of terminal-receiving cavities  7  run from the top  4   c  to the bottom  4   d  of the inner housing  4 . 
     As best seen from FIGS. 11 and 12, the terminal-receiving cavities  7  are rectangular in shape and are arranged to form a lattice pattern in which each cavity  7  is arranged with its opposing long sides  8  of the rectangle confronted perpendicularly to a short side of two adjacent rectangular cavities, and with its opposing shorts sides  9  confronted perpendicularly to a long side of two adjacent rectangular cavities. This arrangement leaves an identically sized, predetermined intervening space  10  between each side of a rectangular cavity  7  and its confronting side of each of its surrounding rectangular cavities. In the particular embodiment shown, each long side  8  of the rectangular cavity  7  is approximately twice as long as each short side  9 . 
     This lattice arrangement in the recess  4   c  of the inner housing  4  permits terminal-receiving cavities  7  to be arranged at an increased density while still assuring that the inner housing  4  has physical strength of the housing relatively evenly distributed thereover. In contrast, more conventionally aligned cavity arrangements tend to reduce the physical strength in a direction parallel or perpendicular to the direction of alignment. Thus, an increased number of rectangular cavities per unit area can exist without loss of strength compared with conventional arrangements of aligned cavities. The outer housing  3  has a corresponding plurality of terminal tail-receiving cavities  11  in vertical alignment with the cavities  7  of the lattice arrangement just described. 
     Referring to FIGS. 13,  14  and  15 , each terminal  12  can be seen to include a contact section  13 , a resilient section  14 , and a tail section  15 . These sections are integrally connected with the resilient section  14  disposed between the contact section  13  and the tail section  15 . The contact section  13 , in one embodiment, includes a pair of contact pieces  13   b  and  13   c  integrally connected to a base plate  13   a.  These contact pieces  13   b  and  13   c  are symmetrically arranged to form a V-shaped contact plane defining oblique contact surfaces  16   b  and  16   c  and a narrow valley bottom  13   d.    
     The resilient section  14  of each terminal  12 , in one embodiment, includes a series of connected U-shaped pieces  14   b  arranged alternately in opposite directions, extending from the contact section  13  to the tail section  15 . As shown in FIG. 13, the U-shaped pieces  14   b  may be connected to one another by linear pieces  14   a.  Alternatively, these linear pieces  14   a  can be omitted with the U-shaped pieces  14   b  connected directly to one another. 
     The tail section  15 , in one embodiment, includes a base piece  15   a  and a tail contact  15   b  integrally connected to the base piece  15   a.  The tail contact  15   b  is for electrical connection to an electronic component on a burn-in board (not shown). The base piece  15   a,  in this embodiment, has engagement nails  15   c  formed on its opposite sides. 
     The terminal  12  is relatively wide in the plane in which the resilient section  14  runs in the serpentine pattern shown from the contact section  13  to the tail section  15 , and relatively narrow in the plane perpendicular to the plane in which the resilient section  14  extends in its serpentine pattern. The terminal  12  may be a piece of metal sheet stamped with a punch directed perpendicularly to the relatively wide side  17 . The precise serpentine shape can be stamped out of a piece of thin metal sheet. It may also be possible to form such a terminal  12  by first stamping the resilient section  14  and then bending it alternately in opposite directions to form a series of U-shaped pieces as shown in FIG.  13 . 
     In order to insert the terminal  12  in a selected terminal-receiving cavity  7  in the inner housing  4  and a corresponding tail-receiving cavity  11  in the outer housing  3 , the terminal  12  is aligned with the selected terminal-receiving cavity  7  with its wide and narrow sides,  17  and  18 , respectively, parallel to the long and short sides,  8  and  9 , respectively, of the rectangular cavity  7 . Then the contact section  13  of the terminal  12  is inserted into the rectangular cavity  7  from the bottom of the inner housing  4  until the contact section  13  appears in the recess  4   b,  thereby allowing opposite shoulders  19  of the base piece  13   a  of the contact section  13  to abut on opposing stopper projections  20  formed in the open end of the selected terminal-receiving cavity  7 . After all such terminal-receiving cavities  7  of the inner housing  4  are filled with terminals  12 , the inner housing  4  is fitted into the outer housing  3 , thereby allowing the base pieces  15   a  of the tail sections  15  of the terminals  12  to enter the tail-receiving cavities  11  of the outer housing  3 . The opposing engagement nails  15   c  of the base piece  15   a  of each terminal  12  are brought into engagement with the wall of the tail-receiving cavity  11  by pulling the tail sections  15  protruding from the bottom of the socket body  2 . In this manner, every terminal  12  can be positively held in the socket body  2 . 
     When the terminals  12  are mounted in the inner and outer housings  4  and  3 , each terminal is surrounded by (or centered among) four adjacent terminals which are rotated 90° relative to it. Thus, wide and narrow sides of the base pieces  17  of the contact sections  13  appear alternately in columns or rows of the inner housing  4 . (See FIGS. 11,  12  and  15 ). 
     Preferably, the serpentine resilient section  14  and its component U-shaped pieces  14   b  are sized relatively to the rectangular cavity  7  such that the terminal  12  may be compressed without the pieces  14   b  touching the surrounding wall of the rectangular cavity when the contact section  13  of the terminal  12  is put in contact with a solder ball from an IC package. 
     The burn-in socket preferably has an annular top cover  21  with an opening  23  surrounded by a square frame  22 . Thus, the burn-in socket is open on top, allowing an automatic loading-retrieving device to insert IC packages  24  substantially onto the inner housing  4  of the burn-in socket and remove the IC packages after testing. 
     The top cover  21  is moveable up and down relative to the outer housing and the socket body  2  further includes a cam mechanism preferably having a pair of cams  27  pivotally fixed to the outer housing  3 , cam return springs  26  associated with the cams  27  to bias them into an upright position, and cam follower surfaces  33  formed on a lower surface of the top cover  21 . With such a structure, when the top cover  21  is released by removing an externally applied pushing-down force, the top cover  21  and the inner housing  4  are allowed to rise up to an upper limit position as shown in FIG.  5 . Conversely, when the top cover  21  is pushed down by an external force, the top cover  21  and the inner housing  4  are lowered to a lower limit position as shown in FIG.  9 . An intermediate, or transition, position of these components relative to each other is shown in FIG.  7 . 
     Each cam return spring  26  is, in the illustrated embodiment, disposed between the bottom of the outer housing  3  and a spring seat  29  corresponding to the cam  27 , thereby compressibly forcing the cam  27  to rotate about its pivot to the upright position when no external force acts against this motion. The cam  27  has a cam surface  32  formed on its top for slidably engaging cam follower surface  33  of the annular top cover  22 . In the illustrated embodiment, the cam follower surface  33  includes a gentle slope portion  33   a  and a steep slope portion  33   b.  In the upper limit position, as shown in FIG. 5, the cam surface  32  of each cam  27  rides on the gentle slope portion  33   a  of the cam follower surface  33 . The lowering of the top cover  21  (as by a downward external force) causes the cam surface  32  of each cam  27  to move on the gentle slope  33   a,  thereby tilting the cam  27  as seen in FIG.  7 . Further lowering of the top cover  21  will cause the cam surface  32  to move from the gentle slope portion  33   a  to the steep slope portion  33   b,  thereby tilting the cam  27  further outward toward its lower limit position as seen in FIG.  9 . The subsequent removable of the force applied to push down the top cover  21  permits each cam  27  to return to its upper limit position as shown in FIG. 5, via the transitional position shown in FIG. 7, due to the biasing influence of the return spring  26 . 
     The rotation of cam  37  corresponds not only to up-and-down movement of the top cover  21 , but also to up-and-down movement of the inner housing  4 . The inner housing  4  has a pair of lateral projections  30  formed on its opposite sides, and these lateral projections are adapted to fit loosely in the lateral recesses  31  of the confronting cams  27 . When the cams  27  are upright (the upper limit position—see FIG. 5) without any external downward force applied to them, the lateral projections  30  are fit in the lateral recesses  31  of the confronting cams  27  and the engagement nails  6  of the inner housing  4  are caught by the counter-engagement nails  5  of the outer housing  3 . This is referred to as the “Cover-Returning, Upper Limit Position”. Prior to the next burn-in test, the top cover  21  is pushed down to force each cam  27  to incline outwardly, thereby allowing the cam surface  32  of each cam  27  to make the gentle-to-steep slope transition and allow each lateral projection  30  of the inner housing  4  to begin leaving the lateral recess  31  of the cam  27 . Thus, the lateral projection  30  of the inner housing  4  and, necessarily, the inner housing  4  itself, are lowered into the transitional or intermediate position shown in FIG.  7 . This position is the referred to as “Cover-Descending, Intermediate Position”. 
     Subsequently, the top cover  21  is lowered to the lower limit position as the cam surface  32  of each cam  27  rides the steep slope portion  33   b  until the cam  27  is in a completely tilted position. Accordingly, the inner housing  4  is lowered to its lowest position. (See FIG. 9.) This position is the “Cover-Descending, Lower Limit Position”. The cam  27 , the cover  21 , and the inner housing  4  are configured and sized so as to cooperate as described above. 
     In the “Cover-Returning, Upper Limit Position” (FIGS.  5  and  6 ), IC packages  24  can be subjected to a burn-in test referred to as (“Burn-In Test Affecting Time”). In the “Cover-Descending, Intermediate Position” (FIGS.  7  and  8 ), the burn-in test is completed and the IC packages  24  are either about to be removed from the socket or about to have a burn-in test conducted (“transition time”). In the “Cover-Descending, Lower Limit Position” (FIGS.  9  and  10 ), the burn-in test is completed and the IC package can be removed from the burn-in socket  1  through the center opening  23  of the top cover  21  or the IC package  24  to be tested can be placed substantially on the inner housing  4  through the center opening  23  of the cover  21  for a burn-in test (“Releasing or Loading Time”). 
     During the “Burn-In Test Affecting Time” (FIGS.  5  and  6 ), the IC package  24  must be positively held. For this purpose, the burn-in socket has a latching mechanism placed below the top cover  21 . In the illustrated embodiment, the latching mechanism includes a pair of L-shaped latch arms  34  pivotally fixed to the outer housing  3 , latch return springs  35  associated with the L-shaped latch arms  34  to bias the angles  34   a  of the latch arms  34  against the IC package  24 , and latch actuators  38  associated with the L-shaped latch arms  34  to incline them toward the releasing position against the latch return springs  35 . With this arrangement, the IC package  24  can be held at its top against the inner housing at the “Burn-In Test Affecting Time” (see FIG.  6 ), and it can be released subsequent to the termination of the burn-in test as described below in detail. 
     Each L-shaped latch arm  34  (FIGS. 16 and 17) has an inclining piece  36  pivotally fixed to the outer housing  3  at an angular position 90° from each cam  27 . This permits each L-shaped latch arm  34  to pivot toward its opposing latch arm  34  for holding the IC package  24  or apart from its opposing latch arm  34  for releasing the IC package  24 . Normally, the confronting L-shaped latch arms  34  are held in the latching position under the influence of the latch return springs  35 . At the “Burn-In Test Affecting Time” (the top cover  21  being not pushed down) the confronting L-shaped latch arms  34  hold the IC package  24  by pressing their latching surfaces  34   a  on the top surface of the IC package  24  (see FIGS.  5  and  6 ). Referring to FIGS. 18 and 19, the top cover  21  has four unlatching rods  38  formed on its bottom to abut on the oppositely inclining pieces  36 , thereby serving as latch actuators. The top cover  21  has engagement rods  22   a  formed on its bottom to catch the socket body  2 . 
     At the “Transition Time” (the top cover  21  in the process of being pushed down), the unlatched rods  38  approach the inclining pieces  36  (see FIGS.  7  and  8 ), and at “Releasing or Loading Time”, prior at which time the top cover  21  is in is lowest position (see FIGS.  9  and  10 ), the unlatching rods  38  force the L-shaped latch arms  34  to incline away from the top surface of the IC package  24 , thereby permitting an automatic loading and removing machine to remove the IC package  24  from the burn-in socket  1  (or to put an IC package  24  into the burn-in socket  1 ). 
     The confronting L-shaped latch arms  34  stand upright at the “Transition Time” (FIGS. 7 and 8) to hold the IC package  24  relative to the inner housing  4 , thereby preventing the IC package  24  from falling from the inner housing  4  or being displaced laterally thereon. The L-shaped latch arms  34  are opened just prior to “Releasing or Loading Time.” For this purpose, the cam surface  32  of each cam  27  is designed to ride the gentle slope portion  33   a  of the cam follower surface  33  so that the top cover  21  and the inner housing  4  may correspondingly be allowed to descend slowly from the end of the “Burn-In Test Affecting Time” to the end of the “Transition Time”, and descend quickly from the end of the “Transition Time” to the “Loading and Releasing Time”. 
     If the IC package  24  falls from the inner housing  4  or is displaced somewhat on the inner housing at the “Transition Time” (see FIGS.  7  and  8 ), then the burn-in test cannot be effected satisfactorily. To prevent such disadvantage, the L-shaped latch arms  34  stand upright at the “Transition Time” to hold the IC package  24  (see FIG. 8) and are opened just prior to “Releasing or Loading Time” (see FIG.  10 ). To deter falling or displacement prior to holding, the top cover  21  and the inner housing  4  descends slowly from the “Burn-In Test Effecting Time” to the end of the “Transition Time” by providing that the cam surface  32  of the cam  27  moves along the gentle slope portion  33   a  of the cam follower surface  33  during this period. Then, after the “Transition Time” until the “Releasing or Loading Time” the top cover  21  and inner housing  4  descend more quickly as the cam surface  32  moves along the steep slope portion  33   b  of the cam follower surface  33 . In this manner, the IC package  24  can be held steadily on the inner housing  4  with the aid of the L-shaped latch arms  34  just prior to the “Releasing or Loading Time” so that burn-in test can be effected satisfactorily. The manner in which a burn-in test is effected with burn-in socket  1  is described below. 
     Referring now to FIGS. 5 and 6, during the burn-in test, no downward force is applied to the top cover  21 , thereby allowing the cams  27  to stand upright, with their cam surfaces  32  disposed at their starting positions on the gentle slope portion  33   a  of the cam follower surfaces  33 . The top cover  21  sits at its upper limit position and the opposing projections  30  of the inner housing  4  are loosely fitted in the recesses  31  of the cams  27 . The engagement nails  6  of the inner housing  4  are caught by the counter-engagement nails  5  of the outer housing  3 . The opposing L-shaped latch arms  34  stand upright to hold the IC package  24  against the inner housing  4  by putting the latching surfaces  34   a  on the top surface of the IC package  24 . In this manner, the solder balls  25  of the IC package  24  are placed in contact with the contact sections  13  of the terminals  12  disposed in the inner housing  4 , so that the burn-in test may be affected. 
     Referring now to FIG. 15, the inner housing  4  is retained at the upper limit position and the IC package  24  is held to the inner housing  4  with the L-shaped latch arms  34 . When the solder balls  25  of the IC package  24  contact the contact sections  13  of the terminals  12  of the inner housing  4 , the terminals  12  are placed into compression, and the stored compression force results in a convergence of the U-shaped pieces  14   b  in that the piece-to-piece interval is reduced. Absorbing the compressional force in this manner, however, minimizes lateral bending, and, therefore, a resilient serpentine portion  13  of the terminal  12  is not forced into a wall of the terminal-receiving cavity  7  in which it sits. Rather, the resilient section of each terminal is reduced evenly over its length. This permits each terminal  12  to produce a stable resilient force to be applied to its corresponding solder ball each time a burn-in test is effected, regardless whether the terminal sides is reduced in an attempt to increase terminal density. The resilient serpentine portion  13  of the terminal  12  thus facilitates the design and arrangement of smaller sized terminals at increased densities while assuring that good physical and electrical contact be maintained with the corresponding solder balls. 
     As mentioned above, every terminal  12  can produce a stable resilient force to be applied to a selected solder ball. More specifically, the solder ball  25  is put in contact with a pair of contact pieces  13   b  and  13   c,  which are urged toward the solder ball  25  under the influence of the resilient force stored in the resilient section  14  of the terminal  12 . Thus, the confronting paired contact pieces  13   b  and  13   c  are positively applied to the solder ball  25 , thereby allowing no error into the interface between the confronting paired contact pieces  13   b  and  13   c  and the solder ball  25 . Elimination of the error deters a significant electrical resistance from appearing at the interface. Even if a selected solder ball were sized within a prescribed allowance, the paired contact pieces defining a V-shaped contact surface would assure that a good electrical contact was made. 
     As described earlier, the terminal-receiving cavities  7  are arranged to form a unique lattice pattern in which each cavity is arranged in a particular orientation with respect to each adjacent cavity. As shown best in FIGS. 1 and 11, each cavity  7  is illustrated as generally rectangular in configuration and having a pair of first (and long in length) opposing sides  8  that are interconnected by a pair of second (and short in length) opposing sides  9 . In the lattice pattern, at least one of the opposing long sides  8  of each cavity is confronted by one short side  9  of each of two adjacent cavities. Similarly, at least one of the opposing short sides  9  of each cavity is confronted by the long sides  8  of adjacent cavities (shown in the drawings as two such adjacent cavities). This arrangement permits an intervening space  10  to occur between the sides of one selected cavity and the confronting sides of each of the surrounding and adjacent cavities. 
     Each terminal-receiving cavity  7  contains a terminal  12  with its wide or long, side  17  and its narrow or short, side  18  arranged respectively parallel to the long side  8  and short side  9  of its associated cavity  7 . The solder balls  25  of the IC package  24  are arranged to correspond to the terminals housed within the cavities in the specified lattice pattern as described. This lattice arrangement permits all of the terminals  12  to be arranged at a substantially equal cavity-to-cavity spacing  10 , which permits increasing the density of the terminals  12 . 
     As appreciable from the foregoing description, the inventive socket and method provide significant advantages over conventional burn-in test sockets and methods for conducting burn-in tests of integrated circuits. The unique lattice arrangement of terminal-receiving cavities and terminals therein permits increased terminal density without compromising the strength and physical performance characteristic of the test socket. Furthermore, the interaction of the cam mechanism and latch mechanism relative to the timing of the insertion/removal of the integrated circuit from the socket, and the relative gentle and steep sloped portions of the interaction between the cam surface and cam follower surface provide a reliable socket and method for burn-in testing of integrated circuits, for in the risk of fallen or dislocated integrated circuits is minimized. 
     The invention is not limited to the embodiment(s) described herein or to any particular embodiment. Specific examples of alternative embodiments considered to be within the scope of the invention, without limitation, include embodiments wherein a common actuation mechanism for the cam mechanism and latch mechanism is dissimilar to a top cover, wherein the cam and latch mechanisms include more or fewer than two rotatable components, wherein the cam or latch return biasing force is accomplished by means other than springs, the non-uniform slope relating to the interaction between the cam surface and the cam follower surface is not limited to a single component, and wherein the portions of perpendicular sides of the terminal-receiving cavities are other than as described or shown herein. Other modifications to the described embodiment(s) may also be made within the scope of the invention. The invention is defined by the following claims.