Abstract:
A test socket ( 52 ) for a semiconductor component ( 12 ) includes a base ( 54 ), a movable lid ( 56 ), socket contacts ( 68 ) for electrically engaging terminal contacts ( 14 ) on the component ( 12 ), and a retention mechanism ( 74 ) having latches ( 74 ) actuated by movement of the lid ( 56 ) for inward and outward movement during retention and release of the component ( 12 ). Such lid ( 56 ) and latch ( 74 ) movement provides a loading/unloading position, in which the component ( 12 ) can be loaded or unloaded, and then a testing position, in which the component ( 12 ) is retained by the retention mechanism ( 74 ) in electrical communication with the socket contacts ( 68 ). The test socket ( 52 ) also includes a nest ( 58 ) for aligning the component ( 12 ), which is configured for removal or installation in the testing position of the test socket ( 52 ) while the latches ( 74 ) are in the inward or retention position. To permit such removal, the nest ( 58 ) includes openings ( 84 ) in a support surface ( 82 ) so that the nest ( 58 ) can be removed even though the latches ( 74 ) are inwardly positioned.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a division of Ser. No. 10/425,202 filed Apr. 28, 2003, U.S. Pat. No. 6,998,862 B2. 

   FIELD OF THE INVENTION 
   This invention relates generally to semiconductor manufacture and testing. More particularly, this invention relates to a test socket for testing semiconductor components, to a method for testing semiconductor components using the test socket, and to test systems incorporating the test socket. 
   BACKGROUND OF THE INVENTION 
   Semiconductor components, such as dice and packages, are tested at the wafer level prior to being singulated into separate components, and then at the die level prior to shipment. For certifying a component as a known good die (KGD), the component must also be burn-in tested. Burn-in tests are typically performed by placing a singulated component in a test socket on a burn-in board. The burn-in board mounts to an oven in electrical communication with test circuitry. The test socket provides electrical connections for addressing the integrated circuits on the component, while the component is subjected to elevated temperatures for an extended period of time. 
   The test socket includes contacts for electrically engaging the terminal contacts on the component. For example, the terminal contacts on the component can comprise bumps, balls, or leads, and the socket contacts can comprise springs, pins or beams. One type of test socket includes a nest which functions to align the component in the socket, such that the socket contacts electrically engage the terminal contacts on the component. 
   As the industry advances, semiconductor manufacturers are developing new components having smaller peripheral outlines (footprints), and denser configurations of terminal contacts. For example, a second generation component, such as a chip scale package (CSP), typically has a smaller outline than a first generation component, such as a ball grid array (BGA) device. These differences in size require that the test sockets be modified to accommodate the later generation components. For example, the nest in a test socket can be replaced by a different nest configured to align the second generation component in the test socket. With some prior art test sockets it is difficult to replace the nest in the field without damaging or stressing other elements of the test socket, particularly the socket contacts. 
   Referring to  FIGS. 1A–1B  and  2 A– 2 B, a prior art burn-in test socket  10  configured to electrically engage a semiconductor component  12  ( FIG. 2A ) having a pattern of terminal contacts  14  ( FIG. 2A ) is illustrated. In this example the component  12  comprises a chip scale semiconductor package, and the terminal contacts  14  comprise solder bumps, or balls, in an area array (e.g., ball grid array). The test socket  10  includes a base  16  ( FIGS. 1A and 2A ), a movable lid  18  ( FIGS. 1A–1B  and  2 A–B) and a nest  20  ( FIGS. 1B and 2B ). 
   The base  16  includes four cylindrical mounting pins  22  ( FIGS. 1A and 2A ) configured for mounting the test socket  10  to a burn-in board (not shown) having mating circular openings (not shown) for engaging the mounting pins  22 . The base  16  also includes a plurality of pin contacts  24  ( FIGS. 1A and 2A ) configured to electrically engage mating contacts (not shown) on the burn-in board. The base  16  also includes a contact plate  26  ( FIGS. 1B and 2B ) having a checker board pattern of generally rectangular openings  28  ( FIGS. 1B and 2B ), that correspond in size and location to the terminal contacts  14  on the component  12 . In addition, selected openings  28  on the contact plate  26  include socket contacts  30  ( FIGS. 2A and 2B ) in electrical communication with the pin contacts  24  ( FIG. 1A ), which are configured to electrically engage the terminal contacts  14  on the component  12 . 
   The lid  18  is movably mounted to the base  16 , and operates a pair of retention mechanisms  32  configured to retain the component  12  on the contact plate  26 . The retention mechanisms  32  comprise latches that contact the top of the component  12  proximate to opposing longitudinal edges thereof to hold the component  12  on the contact plate  26 . Springs  34  ( FIG. 1A ) on the base  16  bias the lid  18  and the retention mechanisms  32  to a testing position shown in  FIGS. 1A and 2A , in which the component  12  is retained on the contact plate  26  with the terminal contacts  14  ( FIGS. 2A and 2B ) in electrical communication with the socket contacts  30  ( FIGS. 2A and 2B ). In  FIGS. 1A and 1B , the socket  10  is shown in the testing position, but without the component  12  having been loaded into the socket  10 . 
   Compression of the lid  18  to the loading/unloading position shown in  FIGS. 2A and 2B , operates the retention mechanisms  32 , such that the component  12  can be loaded into the test socket  10  without interference from the retention mechanisms  32 . Also in the loading/unloading position, the location of the contact plate  26  is shifted such that the terminal contacts  14  on the component  12  can enter the openings  28  on the contact plate  26  without interference from the socket contacts  30 . 
   Referring to  FIGS. 3A–3C  and  4 , the nest  20  is shown separately, after having been removed from the test socket  10 . The nest  20  functions as an alignment member for aligning the component  12  in the test socket  10 . In addition, the nest  20  can be removed from the test socket  10 , and replaced by a second nest (not shown) configured to align a different component (not shown) in the test socket  10 . 
   The nest  20  has a peripheral outline that matches the outline of a hollow interior portion  36  ( FIG. 2B ) of the test socket  10 . In addition, the nest  20  includes clip members  38  on opposing lateral sides thereof, which mate with matching clip elements  40  ( FIG. 5A ) on the base  16  of the test socket  10 . The clip members  38  attach the nest  20  to the base  16 , but can be manipulated for removing the nest  20  from the base  16 . 
   The nest  20  also includes a sloped alignment surface  42  for aligning the component  12 , as it is inserted into the test socket  10 . In addition, the nest  20  includes a support surface  44  for supporting the component  12  on the contact plate  26  ( FIG. 2B ) of the test socket  10 . The support surface  44  includes an opening  46  therein which allows the terminal contacts  14  ( FIG. 2A ) on the component  12  to contact the socket contacts  30  on the base  16 . 
   The nest  20  also includes cut out openings  48  on opposing longitudinal sides thereof, which allow the retention mechanisms  32  ( FIGS. 1B and 2B ) to move from the loading/unloading position of the test socket  10  ( FIG. 2B ) to the testing position of the test socket  10  ( FIG. 1B ). In the testing position of  FIG. 1B , the retention mechanisms  32  extend through the openings  48  to hold the component  12  on the contact plate  26 . In the loading/unloading position of  FIG. 2B , the retention mechanisms  32  retract through the openings  48  to allow the component  12  to be placed on the contact plate  26 . 
   One aspect of the test socket  10  is that the nest  20  cannot be removed without compressing the lid  18 , and shifting the test socket  10  to the loading/unloading position of  FIG. 2A .  FIG. 5A  illustrates the base  16  of the test socket  10  in the loading/unloading position with the nest  20  removed.  FIG. 5B  illustrates the base  16  of the test socket  10  in the testing position with the nest  20  removed. In the testing position the retention mechanism  32  engage portions  50  ( FIG. 4 ) of the support surface  44  of the nest, such that the nest cannot be extracted from the test socket  10 . 
   One problem with having to shift the test socket  10  to the loading/unloading position to remove the nest  20  is that it is difficult to perform in the field with the test socket attached to a burn-in board. Although the nest  20  can be removed in the field, the test socket  10  must often be removed from the burn-in board and transferred to a bench for removing the nest  20 . In addition, with the test socket  10  in the loading/unloading position the socket contacts  30  ( FIG. 2B ) are more susceptible to damage because they are “open” for receiving the terminal contacts  14 . It would be desirable to be able to remove and service the nest  20  in the testing position of the test socket  10  ( FIG. 1B ). 
   The present invention is directed to a test socket having a nest that can be easily serviced or replaced in the field without shifting the test socket to a loading/unloading position, and without damaging other components of the test socket, such as the socket contacts. In addition, the present invention is directed to a method for testing semiconductor components using the test socket, and to test systems incorporating the test socket. 
   SUMMARY OF THE INVENTION 
   In accordance with the invention a test socket for testing semiconductor components, a method for testing semiconductor components using the test socket, and test systems incorporating the test socket are provided. 
   The test socket includes a base, a lid attached to the base, and a nest removably attached to the base. The base includes a contact plate with a pattern of socket contacts configured to electrically engage terminal contacts on a component. The lid is operably associated with a retention mechanism on the base configured to retain the component on the contact plate. In addition, the lid is movable from a testing position in which the retention mechanism is positioned to retain the component on the contact plate, to a loading/unloading position in which the retention mechanism is positioned to allow the component to be placed on, or removed from, the contact plate. 
   The nest is configured to align the component in the test socket, such that the socket contacts on the contact plate electrically engage the terminal contacts on the component. In addition, the nest includes openings and a support surface configured to allow the nest to be removed from the test socket in the testing position, without interference from the retention mechanism. Because the nest can be removed with the test socket in the testing position, damage to the socket contacts can be minimized, and the nest can be serviced or replaced in the field. 
   The method for testing includes the steps of providing the test socket, and testing a first component using the test socket. In addition, the method includes the step of removing the first component from the test socket, and the step of removing the nest from the test socket with the test socket in the testing position. The method also includes the steps of placing a second nest for a second component into the test socket with the test socket in the testing position, placing the second component into the test socket, and then testing the second component. 
   The system includes a burn-in board, and one or more test sockets mounted to the burn-in board for retaining and electrically engaging the components. The test system can also include a testing circuit in electrical communication with the burn-in board and with the test sockets on the burn-in board, and a burn-in oven configured to heat the components on the burn-in board. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is an enlarged schematic side elevation view of an unloaded prior art test socket shown in a testing position; 
       FIG. 1B  is an enlarged schematic plan view of the prior art unloaded test socket in the testing position taken along section line  1 B— 1 B of  FIG. 1A ; 
       FIG. 2A  is an enlarged schematic side elevation view of the prior art test socket shown in a loading/unloading position; 
       FIG. 2B  is an enlarged schematic plan view of the test socket in the loading/unloading position; 
       FIG. 3A  is an enlarged schematic plan view of a prior art nest for the prior art test socket; 
       FIG. 3B  is an enlarged schematic cross sectional view of the prior art nest taken along section line  3 B— 3 B of  FIG. 3A ; 
       FIG. 3C  is an enlarged schematic cross sectional view of the prior art nest taken along section line  3 C— 3 C of  FIG. 3A ; 
       FIG. 4  is an enlarged schematic perspective view of the prior art nest; 
       FIG. 5A  is an enlarged schematic plan view of the prior art test socket in the loading/unloading position equivalent to  FIG. 2B  but with a nest element removed; 
       FIG. 5B  is an enlarged schematic plan view of the prior art test socket in the testing position equivalent to  FIG. 1B  but with a nest element removed; 
       FIG. 6A  is an enlarged schematic side elevation view of a test socket constructed in accordance with the invention in a testing position; 
       FIG. 6B  is an enlarged schematic plan view of the test socket in the testing position taken along section line  6 B— 6 B of  FIG. 6A ; 
       FIG. 7A  is an enlarged schematic plan view of the test socket of the invention in the testing position, similar to  FIG. 6B , but showing the test socket loaded with the component; 
       FIG. 7B  is an enlarged schematic cross sectional view taken along section line  7 B— 7 B of  FIG. 7A  illustrating terminal contacts on the component engaging socket contacts on the test socket of the invention in the testing position; 
       FIG. 7C  is an enlarged schematic cross sectional view taken along section line  7 C— 7 C of  FIG. 7B  illustrating the terminal contacts engaging the socket contacts in the testing position; 
       FIG. 8A  is an enlarged schematic plan view of a nest element of the test socket of the invention; 
       FIG. 8B  is an enlarged schematic cross sectional view of the nest taken along section line  8 B— 8 B of  FIG. 8A ; 
       FIG. 8C  is an enlarged schematic cross sectional view of the nest taken along section line  8 C— 8 C of  FIG. 8A ; 
       FIG. 9  is an enlarged schematic perspective view of the nest; and 
       FIGS. 10A–10D  are schematic cross sectional views illustrating a test system incorporating the test socket of the invention and steps in a test method performed using the test system. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As used herein, the term “semiconductor component” refers to an electronic element that includes a semiconductor die. Exemplary semiconductor components include semiconductor packages, semiconductor dice, BGA devices, and DDC devices. 
   Referring to  FIGS. 6A and 6B , a test socket  52  constructed in accordance with the invention is illustrated. The test socket  52  includes a base  54 , a movable lid  56  attached to the base  54 , and a nest  58  attached to the base  54 . The elements of the test socket  52  can be fabricated out of rigid high temperature materials that are known in the art, such as molded plastic and metal. 
   The base  54  includes four cylindrical mounting pins  60  configured for mounting the test socket  52  to a burn-in board  102  ( FIG. 10A ) having mating circular openings for engaging the mounting pins  60 . The base  54  also includes a plurality of pin contacts  24 ,  62  configured to electrically engage mating contacts on the burn-in board  102  ( FIG. 10A ) in electrical communication with a testing circuitry  104  ( FIG. 10A ). 
   As shown in  FIG. 6B , the base  54  also includes a contact plate  64  having a checker board pattern of generally rectangular openings  66 , that correspond in size and location to the terminal contacts  14  ( FIG. 7A ) on the component  12  ( FIG. 7A ). The contact plate  64  is similar in construction to a screen and the openings  66  correspond to the openings in the screen. In addition, selected openings  66  on the contact plate  64  include socket contacts  68  in electrical communication with the pin contacts  62 , which are configured to electrically engage the terminal contacts  14  ( FIG. 7A ) on the component  12  ( FIG. 7A ). With the base  54  mounted to the burn-in board  102  ( FIG. 10A ) the pin contacts  62  and the socket contacts  68  are in electrical communication with the testing circuitry  104  ( FIG. 10A ). 
   The lid  56  is movably mounted to the base  54 , and operates a pair of retention mechanisms  74  configured to retain the component  12  on the contact plate  64 . In addition, the lid  56 , and the base  54  as well, have a hollow interior portion  72  which allow the nest  58  and the component  12  to be inserted therein. As shown in  FIG. 7A , the retention mechanisms  74  comprise a pair of clasps that contact the top surface of the component  12  proximate to opposing longitudinal edges thereof, to hold the component  12  on the contact plate  64 . Alternately, the retention mechanisms  74  can comprise bails, latches or any other retention mechanism used in the art. 
   Springs  70  ( FIG. 6A ) on the base  54  bias the lid  56  and the retention mechanisms  74  to the testing position shown in  FIGS. 6A and 6B , in which the component  12  is retained on the contact plate  64  with the terminal contacts  14  in electrical communication with the socket contacts  68 . In  FIGS. 6A and 6B , the socket  52  is shown in the testing position, but without the component  12  having been loaded into the socket  52 . 
   In  FIG. 7A , the socket  52  is shown in the testing position with the component  12  retained on the contact plate  64  by the retention mechanisms  74 . As shown in  FIGS. 7B and 7C , with the socket  52  in the testing position, the socket contacts  68  electrically engage the terminal contacts  14  on the component  12 . In addition, the openings  66  in the contact plate  64  function as a fine alignment mechanism for aligning the terminal contacts  14  to the socket contacts  68 . 
   Compression of the lid  56  to the loading/unloading position operates the retention mechanisms  74 , such that the component  12  can be loaded into the test socket  52  without interference from the retention mechanisms  74 , substantially as previously described for the test socket  10  ( FIGS. 2A and 2B ). Also in the loading/unloading position, the location of the contact plate  64  is shifted such that the terminal contacts  14  on the component  12  can enter the openings  66  on the contact plate  64  without substantial interference from the socket contacts  68 . This type of test socket  52  is sometimes referred to as a zero insertion force (ZIF) socket, because no forces are exerted on the terminal contacts  14  during insertion of the component  12  into the test socket  52 . 
   Referring to  FIGS. 8A–8C  and  9 , the nest  58  for the test socket  52  is shown separately. The nest  58  is similar in construction to the prior art nest  20  ( FIG. 4 ). However, the nest  58  differs from the previously described nest  20  ( FIG. 4 ) in that it is designed to be removed and inserted with the test socket  52  in the testing position ( FIG. 6A ). 
   The nest  58  comprises a molded plastic member having a peripheral outline that matches the outline of the hollow interior portion  72  ( FIG. 6B ) of the test socket  52 . In addition, the nest  58  includes clip members  76  on opposing lateral sides thereof, which mate with matching clip elements  78  ( FIG. 6B ) on the base  54  of the test socket  52 . The clip members  76  attach the nest  58  to the base  54  of the test socket  52 , but can be manipulated for removing the nest  58  from the base  54 . 
   The nest  58  also includes an alignment opening  80  having sloped alignment surfaces for aligning the component  12 , as it is inserted into the test socket  52 . The alignment opening  80  can have a peripheral outline which substantially matches the peripheral outline of the component  12 , but with the alignment surfaces tapered from a larger to a smaller peripheral outline. In addition, the nest  58  includes a support surface  82  for supporting the component  12  on the contact plate  64  ( FIG. 6B ) of the test socket  52 . The support surface  82  has a generally rectangular picture frame shape with a generally rectangular opening  88 . The support surface  82  supports the outside periphery of the component  12 , while the opening  88  allows the terminal contacts  14  ( FIG. 2A ) on the component  12  to contact the socket contacts  68  on the base  54  of the test socket  52 . The support surface  82  is shaped to support the component  12  during electrical engagement of the terminal contacts  14  by the socket contacts  68  but to allow removal or installation of the nest  58  from the base  54  without interference from the retention mechanisms  74 . 
   In addition, the support surface  82  is configured to not contact the retention mechanisms  74  in either position of the test socket  52 , such that the nest  58  can be removed from the test socket  52  with the test socket  52  in the testing position of  FIG. 7A . This allows the nest  58  to be removed in the field, (e.g., at the test site), without having to remove the test socket  52  from the burn-in board  102  ( FIG. 10A ). In addition, with the test socket  52  in the testing position, the socket contacts  68  ( FIG. 7C ) are not as easily damaged during removal of the nest  58  from the test socket  52 . Because the nest  58  can be more easily removed, serviced and replaced it is termed herein as a “serviceable nest”. 
   The nest  58  also includes cut out openings  84  on opposing longitudinal sides thereof, which are located in the in the support surface  82 , and in the alignment surface of the alignment opening  80 . The cut out openings  84  allow the retention mechanisms  74  ( FIG. 7A ) to, move from the testing position of the test socket  52  ( FIG. 6A ) to the loading/unloading position of the test socket  52  without interference from the nest  58 . In the testing position of  FIG. 7A , the retention mechanisms  74  extend through the openings  84  to hold the component  12  on the contact plate  64  on the base  54 . In the loading/unloading position of the test socket  52 , the retention mechanisms  74  retract through the openings  84  to allow the component  12  to be placed on the contact plate  64  on the base  54 . As the cut out openings  84  extend through the support surface  82 , there is no segment of the support surface  82  proximate to the retention mechanisms  74 . This allows the nest  58  to be inserted into, and also removed from the test socket  52 , without interference from the retention mechanisms  74 . 
   Referring to  FIGS. 10A–10D , a test method using the test socket  52 , and a test system  100  incorporating the test socket  52  are illustrated. As shown in  FIG. 10A , the test system  100  includes a burn-in board  102 , a burn-in oven  112  and a testing circuitry  104  in electrical communication with the burn-in board. 
   The burn-in board  102  is adapted to retain a plurality of test sockets  52  in the burn-in oven  112  in electrical communication with the testing circuitry  104 . The burn-in board  102  includes openings for engaging the mounting pins  60  on the test sockets  52 . In addition, the burn-in board  102  includes electrical receptacles in electrical communication with the testing circuitry  104  for electrically engaging the pin contacts  62  on the test sockets  52 . 
   The testing circuitry  104  is adapted to generate and apply test signals to the integrated circuits on the components  12 , or to simply apply a biasing voltage to the integrated circuits on the component  12 . The burn-in oven  112  is adapted to heat the burn-in board  102 , the test sockets  52  and the components  12  therein, to an elevated temperature, for an extended period of time, in order to perform burn-in testing of the components  12 . As used herein, the term “burn-in testing” means the process of electrically stressing the components  12  at an elevated temperature and voltage environment, for a period of time sufficient to cause failure of marginal components  12 . 
   Initially, the components  12  (first components in the claims) can be loaded into the test sockets  52  using automated or manual equipment and techniques that are known in the art. As shown in  FIG. 10A , the components  12  are burn-in tested with the test sockets  52  on the burn-in board  102  in the testing position. In the testing position the components  12  are retained by the retention mechanisms  74 , substantially as shown in  FIGS. 7A–7C , with the terminal contacts  14  on the components  12  in electrical communication with the socket contacts  68  on the test sockets  52 , and with the testing circuitry  104  in electrical communication with the socket contacts  68 . 
   Next, as shown in  FIG. 10B , following burn-in testing of the components  12 , the burn-in board  102  can be removed from the burn-in oven  112 , and the tested components  12  removed from the test sockets  52 , as indicated by component removal arrows  106 . However, prior to removing the components  12 , the test sockets  52  must be shifted from the testing position to the loading/unloading position. The test sockets  52  can be placed in the loading/unloading position, and the components  12  removed, using an automated or manual mechanism, such as a test handler, configured to apply a biasing pressure to the lids  56 , and then to remove the components  12 . 
   Next, as shown in  FIG. 10C , following removal of the components  12 , the test sockets  52  can be shifted back to the testing position. In this regard, the springs  70  will automatically shift the test sockets  52  back to the testing position, once the biasing pressure on the lids  56  is removed. As also shown in  FIG. 10C , with the test sockets  52  in the testing position, the nests  58  (first nests in the claims) can be removed from the test sockets  52 , as indicated by nest removal arrows  108 . The nests  58  can be removed from the test sockets  52  using automated or manual tools that are known in the art. Because the test sockets  52  are in the testing position, damage to the socket contacts  68  ( FIG. 7C ) during removal of the nests  58  is substantially reduced or eliminated. In addition, the configuration of the support surfaces  82  and the cut out openings  84  of the nests  58 , allow the nests  58  to be removed without interference or damage to the retention mechanisms  74  ( FIG. 6B ). Further removal of the nests  58  can be accomplished with the test sockets  52  still mounted to the burn-in board  102 . 
   Next, as shown in  FIG. 10D , following removal of the nests  58  and with the test sockets  52  still in the testing positions, replacement nests  58 A (second nests in the claims) can be installed in the test sockets  52 , as indicated by nest installation arrows  110 . Installation of the replacement nests  58 A can be accomplished with the test sockets  52  still mounted to the burn-in board  102 . 
   With the replacement nests  58 A installed in the test sockets  52 , the replacement nests  58 A can be utilized to align second components  12 A in the test sockets  52  having different peripheral outlines than the components  12 . With the replacement nests  58 A installed in the test sockets  52 , the test sockets  52  can be shifted to the loading/unloading positions, and the second components  12 A can be loaded into the test sockets  52 , substantially as previously described. The second components  12 A can then be burn-in tested substantially as previously described. 
   Thus the invention provides an improved test socket for semiconductor components having a serviceable nest that can be easily removed and replaced in the field with the test socket in a testing position and without damage to the test socket. Also provided are test methods performed using the test socket, and test systems incorporating the test socket. While the invention has been described with reference to certain preferred embodiments, as will be apparent to those skilled in the art, certain changes and modifications can be made without departing from the scope of the invention as defined by the following claims.