Abstract:
An intercoupling component used to couple an array of electrical connection regions disposed on a first substrate to an array of electrical connection regions disposed on a second substrate. The intercoupling component includes an insulative support member including an array of holes extending therethrough, the array of holes located in a pattern corresponding to the array of electrical connection regions on the first substrate; and a plurality of terminals. Each terminal includes a socket including a socket head and a socket body, the socket defining a socket cavity; a pin including a pin head and a pin body, the pin head positioned within one of the array of holes, the pin body extending from the pin head and received at least partially within the socket cavity; and a resilient member configured to bias the socket head is biased away from the pin head.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to making connections between integrated circuit (IC) packages and circuit boards. 
       BACKGROUND 
       [0002]    Ball grid array (BGA) and land grid array (LGA) packages are becoming increasingly popular because of their low profiles and high densities. With a BGA package, for example, the rounded solder balls of the BGA are generally soldered directly to corresponding surface mount pads of printed circuit board rather tan to plated thru-holes which receive pins from, for example, a pin grid array (PGA) package. 
         [0003]    Sockets are used to allow particular IC packages to be interchanged without permanent connection to a circuit board. More recently, sockets for use with BGA and LGA packages have been developed to allow these packages to be non-permanently connected (e.g., for testing) to a circuit board. 
       SUMMARY 
       [0004]    This invention features intercoupling components and terminals that can enable high-density interconnections between electrical components such as, for example, printed circuit boards and integrated circuit packages. As used herein, the term “integrated circuit package” is intended to mean integrated circuit packages including, for example, PGA, BGA, and LGA packages. Intercoupling components can include: an insulative support member and a plurality of terminals. Terminals can include a socket, a pin, and a resilient member. 
         [0005]    In an aspect of the invention, intercoupling components, used to couple an array of electrical connection regions disposed on a first substrate to an array of electrical connection regions disposed on a second substrate, include: an insulative support member including an array of holes extending therethrough, the array of holes located in a pattern corresponding to the array of electrical connection regions on the first substrate; and a plurality of terminals, each terminal including: a socket including a socket body extending from a socket head, the socket defining a socket cavity within the socket body; a pin including a pin body extending from a pin head, the pin head positioned within one of the array of holes and contacting the insulative member, the pin body at least partially received within the socket cavity; and a resilient member configured to bias the socket head away from the pin head. 
         [0006]    In another aspect of the invention, terminals, for use with an integrated circuit package having an array of electrical connection regions disposed on a first substrate, include: a socket including a socket body extending from a socket head, a socket cavity formed within the socket, and a socket retaining element disposed on an opposite end of the socket body from the socket head; a pin including a pin body extending from a pin head, the pin body at least partially received within the socket cavity; and a resilient member configured to bias the socket away from the pin head. 
         [0007]    In another aspect of the invention, methods of assembling an intercoupling component include: providing an insulative support member including an array of holes extending therethrough, the array of holes located in a pattern corresponding to the array of electrical connection regions on the first substrate; inserting a socket into each of the array of holes; inserting a pin having a pin body extending from a pin head into each of the array of holes such that the pin head contacts the insulative support member; and inserting a resilient member into each of the array of holes; such that, after the socket, the pin, and the resilient member are inserted, the resilient member is interposed between the pin head and the socket and the pin body is received within a socket cavity defined within the socket. 
         [0008]    Embodiments can include one or more of the following features. 
         [0009]    In some embodiments, the resilient member includes a coiled spring. 
         [0010]    In some embodiments, the resilient member includes electrically conductive material and forms part of a first electrically conductive path between the array of electrical connection regions disposed on the first substrate to the array of electrical connection regions disposed on the second substrate. In some cases, contact between the pin and the socket forms part of a second electrically conductive path between the array of electrical connection regions disposed on the first substrate to the array of electrical connection regions disposed on the second substrate. The pin body can include a protrusion extending radially outward from a cylindrical portion of the pin body and/or the socket body can include a protrusion extending into the socket cavity. 
         [0011]    In some embodiments, each hole includes a first section having a first diameter and a second section having a second diameter that is smaller than the first diameter. In some cases, the pin head is press-fit within the first section of a corresponding hole. In some cases, the pin head is press-fit within the second section of the corresponding hole. 
         [0012]    In some embodiments, the pin head includes a proximal contacting surface. In some cases, the proximal contacting surface includes a ball-shaped end. 
         [0013]    In some embodiments, the socket head includes a concave ball-contacting surface. In some embodiments, the socket head includes a sharp protrusion extending from a contacting surface. 
         [0014]    In some embodiments, a lateral distance between centers of adjacent holes is less than about 0.8 millimeter. 
         [0015]    In some embodiments, the resilient member includes a coiled spring. In some cases, the coiled spring has a coil diameter of less than about 0.005 inch (e.g., less than about 0.0025 inch). 
         [0016]    In some embodiments, the socket comprises a contact spring disposed within the socket cavity. In some cases, the pin body comprises an enlarged end and the pin is received into the socket such that the contact spring engages sides of the pin body between the pin head and the enlarged end. In some cases, the contact spring comprises a first spring end and a second spring end, the first spring end having a greater diameter than the second spring end, the first spring end disposed nearer the pin head than the second spring end. 
         [0017]    In some embodiments, the socket retaining element includes projections extending outward from an outer surface of the socket body. 
         [0018]    In some embodiments, the socket retaining element includes projections extending inward from an inner surface of the socket body. 
         [0019]    In some embodiments, the socket retaining element includes a contact spring disposed within the socket cavity, the contact spring having a first spring end and a second spring end, the first spring end having a greater diameter than the second spring end, the first spring end disposed nearer the pin head than the second spring end. In some cases, the pin body includes an enlarged end and the pin is received into the socket such that the contact spring engages sides of the pin body between the pin head and the enlarged end. 
         [0020]    In some embodiments, the socket head comprises an open end of the socket body. In some cases, the socket head further includes a contacting element inserted into the open end of the socket body with a press-fit engagement between contacting element and the socket body. 
         [0021]    In some embodiments, the resilient member provides a conductive path between the pin and the socket. 
         [0022]    In some embodiments, the resilient member includes a coiled spring. 
         [0023]    In some embodiments, the pin body includes a protrusion extending radially outward from a cylindrical portion of the pin body. 
         [0024]    Terminals and intercoupling components (e.g., socket converter assemblies) as described herein can advantageously provide for an increased density of terminal connections. For example, a terminal having a socket which receives a portion of the pin but in which an interposed spring (i.e., resilient member) is not contained within the socket can have smaller outer dimensions than similar terminals in which the socket must be sufficiently large to contain the spring. Thus, intercoupling components can be configured with a decreased pitch or spacing between the centers of adjacent connections (e.g., 0.8 millimeter or 0.5 millimeter). 
         [0025]    Another advantage relates to applications in which a specific pitch is desired. Reduced terminal diameters can increase the distance between the outer surfaces of adjacent terminals for intercoupling components of a given pitch (e.g., 1 millimeter). This increased separation can limit the “crosstalk” that can occur between adjacent signal paths in high-density intercoupling components. 
         [0026]    The configuration of the pins and sockets can also provide an increased range of motion to compensate for variations of the in the surface of the integrated circuit package being, for example, tested. In addition, because these terminals and intercoupling components can be soldered or connected directly to underlying printed circuit boards, terminals and intercoupling components as described herein dispense with holed drill in printed circuit boards required to install intercoupling components which require separate hold down devices. This can reduce the likelihood of damage to such printed circuit boards. 
         [0027]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
     
       DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  is an exploded, somewhat diagrammatic, perspective view of a BGA converter socket assembly, a BGA package, and a hold-down assembly positioned over a printed circuit board. 
           [0029]      FIG. 2  is a cross-sectional view of the circuit board, two socket terminals of the socket converter assembly, and the BGA package of  FIG. 1 . 
           [0030]      FIGS. 3 - 9  are cross-sectional views of embodiments of socket terminals. 
       
    
    
       [0031]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0032]    Referring to  FIGS. 1 and 2 , a socket converter assembly  10  intercouples a BGA package  12  to a printed circuit board  14 . Socket converter assembly  10  includes an electrically insulative member  16  (e.g., a unitary sheet of liquid crystal polymer plastic, polyphenyl sulfide (“PPS”), or other electrically insulative material) for supporting converter terminals  18 . Each of the terminals  18  is press-fit within a corresponding one of an array of holes  20  ( FIG. 2 ) in insulative member  16 . The array of holes  20  is provided in a pattern corresponding to a footprint of rounded solder balls  51  ( FIG. 2 ) of BGA package  12  as well as a footprint of surface mount pads  24  of printed circuit board  14 . Insulative member  16  with converter socket terminals  18  is press-fit into a guide box  26  having sidewalls  28  along which the peripheral edges of BGA package  12  are guided so that solder balls  51  of the BGA package ( FIG. 2 ) are aligned over converter socket terminals  18 . In some instances, insulative member  16  and guide box  26  can be formed as a one-piece, integral unit. In this illustrative embodiment, socket converter assembly  10  is configured to intercouple BGA package  12  to circuit board  14 . However, as described in more detail below, other socket converter assemblies can be configured with similar terminals to intercouple other types of IC packages (e.g., LGA packages or PGA packages) to circuit boards. 
         [0033]    As is shown in  FIG. 1 , socket converter assembly  10  includes a hold-down cover  30  for securing BGA package  12  into the socket converter assembly. Cover  30  includes a pair of opposite walls  31  having tab members  33  which engage recessed portions  37  along the underside of insulative member  16 . Hold-down cover  30  includes a threaded thru-hole  34  which threadingly receives a heat sink  32  to provide a thermal path for dissipating heat generated within BGA package  12  from the IC device. Heat sink  32  is inserted and backed-in from the bottom of cover  30  and includes a lip  49  which engages a flat counter-bored surface (not shown) on the bottom surface of the cover to ensure that the heat sink will contact the surface of BGA package  12 . A slot  36  formed in heat sink  32  facilitates threading the heat sink (e.g., with a screwdriver or coin) within cover  30 . Other latching mechanisms (e.g., clips or catches) may also be used to secure IC packages within the socket converter assembly. In some instances, other heat sink arrangements, including those with increased surface areas (e.g., heat sinks with finned arrangements), are substituted for the lower profile heat sink shown in  FIG. 1 . In some instances, a heat sink is not required and only cover  30  applies downward force to the IC package. 
         [0034]    Referring to  FIG. 2 , each terminal  18  includes a socket  52 , a pin  54 , and a resilient member  56 . Each socket  52  has a socket head  58  formed at the end of a socket body  60 . In this embodiment, socket heads  52  have concave upper surfaces  59  sized to receive and engage solder balls  51  of BGA package  12 . A socket cavity  62  is located within socket body  60  of each socket  52  and a socket retainer  70  extends outward relative to an outer surface  72  of the socket body. In the illustrated embodiment, socket body is substantially cylindrical in shape but, in some cases, other shapes and configurations are used. Insulative member  16  has projections or detents  64  defining narrow ends  66  of holes  20  that are oriented toward an IC package (e.g., BGA package  12  as illustrated) when converter assembly  10  is in use. Narrow ends  66  of holes  20  have a smaller cross-sectional dimension (e.g., diameter) than wide ends  68  of the holes. Sockets  52  are configured with socket bodies  60  that are sized to fit though narrow ends  66  of holes  20  with socket retainers  70  sized to fit into wide ends  68  of the holes and engage detents  64 . The engagement between socket retainers  70  and detents  64  prevents sockets  52  from passing completely thru-holes  20 . 
         [0035]    Similarly, pins  54  have pin heads  74  formed at ends of pin bodies  76 . Pins  54  are configured with pin bodies  76  sized to have outer dimensions (e.g., diameters) at least slightly smaller than inner dimensions of socket cavities  62  and pin heads  74  sized to engage inner surfaces  78  of wide ends  68  of holes  20 . Each pin head  74  is positioned within a corresponding one of the array of holes  20 . Pin bodies  76  extend from pin heads  74  and can be received at least partially within corresponding socket cavities  62 . 
         [0036]    Resilient members  56  are configured to bias socket heads  58  away from pin heads  74 . In this embodiment, resilient members  56  are springs (e.g., annular springs such as coiled springs or spring washers) positioned around pin bodies  76  with the resilient member of each terminal  18  extending between pin head  74  and socket retainer  70  of the terminal. In certain embodiments, resilient members  56  are made of electrically conductive material (e.g., beryllium copper, stainless steel, or music wire) such that the resilient members provide a electrically conductive connection between sockets  52  and pins  54 . Resilient members  56  are generally sized such, that under normal operation, an outer dimension (e.g., diameter) of the resilient members is smaller than an inner dimension (e.g., diameter) of wide ends  68  of holes  20  and an inner dimension (e.g., diameter) of the resilient members is larger than an outer dimension (e.g., diameter) of pin body  76 . Such sizing facilitates the movement (e.g., compression and expansion) of resilient members  56  in response to forces applied to sockets  52  as described below. 
         [0037]    The above-described configuration can facilitate the installation of terminals  18  in insulative member  16 . In one approach, insulative member  16  is positioned with narrow ends  66  of holes  20  below wide ends  68  of the holes (i.e., rotated 180 degrees from the orientation shown in  FIG. 2 ). Each socket  52  is then placed into corresponding hole  20  with gravity acting to move or help move the socket downward until socket retainer  70  engage detent  64 . Each resilient member  56  can then be placed into corresponding hole  20 . Each pin  54  can then be placed into a corresponding hole  20  with pin body  76  extending through resilient member  56  (e.g., through the open central region of coiled spring). Pressure can then be applied to pin head  74  and/or solder ball  50  attached to the pinhead to compress resilient member  56  and bring the pin head into a press-fit engagement with insulative member  16 . Holes  20  and pins  54  can be sized such that the press-fit engagement between pin heads  74  and insulative member  16  can hold terminals  18  in place against forces applied to the pin heads through sockets  52  and resilient members  56  as BGA package  12  approaches circuit board  14 . 
         [0038]    In operation, terminals  18  can provide electrically conductive paths between IC package  12  and circuit board  14  with individual terminals providing some degree of compensation for irregularities in the surface and/or electrical contacts (e.g., solder balls  51 ) of the IC package. For example, if an individual solder ball  51  extends farther from surface  80  of IC package  12  than other solder balls  51 , the farther-extending solder ball will contact its corresponding socket head  58  sooner than the other solder balls will contact their corresponding socket heads as the IC package approaches (e.g., is pressed towards) insulative member  16 . However, socket head  58  contacted by the farther-extending solder ball  51  will compress resilient member  56  of that specific terminal  18 , thus allowing IC package  12  to continue to approach converter assembly  10  such that all solder balls  51  can be brought into engagement with corresponding socket heads. Thus, the movement of individual terminals  18  can provide improved electrical contact between IC package  12  and overall converter assembly  10 . 
         [0039]    In this embodiment, resilient members  56  provide the primary electrically conductive connection between sockets  52  and pins  54 . However, incidental contact between pin  54  and socket  52  can also provide a direct electrically conductive connection between the pin and the socket and, thus, between IC package  12  and circuit board  14 . In some instances, the outer surface of pin body  76  and/or the inner surface of socket body  60  can be configured with projections to provide contact between pin  54  and socket  52 . However, while such projections can provide a consistent direct electrical contact between pin  54  and socket  52 , the resulting contact can also reduce the ease with which the socket moves relative to the pin and, thus, the ability of individual socket terminals  18  to compensate for irregularities in surface  80  and/or solder balls  50  of IC package  12 . 
         [0040]    In addition to providing for easy assembly, embodiments of terminals  18  can also provide other advantages including improved electrical characteristics and reduced pitch (i.e., spacing between the centers of adjacent terminals). In general, changes in the diameter of components forming the electrically conductive path through a terminal can produce undesirable effects (e.g., reduced bandwidth, increased insertion and/or return signal losses). By limiting the number of such diameter changes, terminals  18  can have improved electrical characteristics relative to other terminals with more diameter changes. This simpler configuration also can allow for machining of terminals components with small diameters and, thus, manufacture of converter assemblies with pitches of less than about 1 millimeter (e.g., 0.8 millimeter, 0.5 millimeter, or 0.3 millimeter). For clarity of illustration, additional embodiments are illustrated in  FIGS. 3-9  with only the insulative member and socket terminals shown. Where the resilient member is shown in a compressed state, it will be understood that such compression would be produced by an IC package engaging the socket heads of the terminals. 
         [0041]    Referring to  FIGS. 3 and 4 , in some embodiments (e.g., in converter assemblies configured to intercouple other types of IC packages to circuit board  14 ), socket heads can be configured to engage other contacts than solder balls. For example, terminals  82  and terminals  83  are configured in substantially similar fashion to terminal  18  ( FIGS. 1 and 2 ) described above. Terminals  82  and terminals  83  are disposed in insulative member  16  and include pin  54 , resilient member  56 , and solder balls  50 . The primary difference between terminals  18  ( FIGS. 1 and 2 ), terminals  82  ( FIG. 3 ), and terminals  83  ( FIG. 4 ) is in their socket head configurations. Referring to  FIG. 3 , terminals  82  have sockets  84  with socket heads  86  whose upper surfaces  88  are substantially flat (rather than concave) with pointed projections extending away from the socket heads. The pointed projection can, to some extent, pierce through the layers of oxidation that sometimes form on the contacts of IC packages. Socket heads  86  provide terminals  82  with a configuration that is appropriate for use with IC packages including, for example, LGA packages. Referring to  FIG. 4 , terminals  83  have sockets  90  with socket heads  92  whose upper surfaces  94  are slightly concave. Socket heads  92  provide terminals  83  with a configuration that is appropriate for use with IC packages including, for example, LGA packages. 
         [0042]    Referring to  FIG. 5 , in some cases, terminals can be is configured such that engagement between the pin and the socket of individual elements retains the socket in the terminal. For example, terminal  96  is disposed in insulative member  16  and includes a pin  98  press-fit within a hole  100  in the insulative member. In this embodiment, resilient member  56  is a coiled spring which can be made of an electrically conductive material. As in the previously embodiments, resilient member  56  biases socket head  102  of socket  104  away from pin head  106 . In this embodiment, resilient member  56  is disposed around pin  98  with ends engaging socket  104  and projections  105  extending from insulative member  16 . Pin  98  includes a pin body  110  having a proximal section  112  and distal section  114  with intermediate projections  108  extending radially outward from pin body  110  between the proximal and distal sections. In some embodiments, distal section  114  has a smaller diameter than proximal section  112 . 
         [0043]    Socket  104  has inward socket retainer  116  disposed at the open end of the socket and extending inward from a substantially tubular socket body  118 . Thus, socket retainers  116  define a thru-hole with a smaller diameter than at least an adjacent portion of socket body  188 . The inner diameter of inward socket retainer  116  is sized to be at least as large as the outer diameter of proximal section  112  of pin body  110  but smaller than the outer diameter of intermediate projections  108  of pin body  110 . The inner diameter of at least a portion of socket body  118  is sized to be at least as large as the outer diameter of intermediate projections  108  of pin body  110 . 
         [0044]    In this embodiment, inward socket retainer  116  is an integrally constructed unit with a substantially annular configuration. However, inward socket retainer  116  can have other configurations (e.g., multiple tabs spaced at intervals around an inner surface of the socket). 
         [0045]    As illustrated, socket head  102  can have the same cross-section as socket body  118 . This configuration facilitates manufacture of socket  104  as socket head  102  and socket body  118  can be a single integral unit with a inner diameter sized and shaped such that the open end of the socket end can receive and engage electrical contacts of an IC package (e.g., solder balls on a BGA package). 
         [0046]    Terminal  96  can be partially assembled before it is installed in insulative member  16 . For example, while holding socket  104  with socket head  102  upwards, pin  98  can be placed into the socket with proximal section  112  of pin body  110  extending downward through inward socket retainers  116  such that intermediate projections  108  of pin body  110  engage inward socket retainers  116 . The assembled pin  98  and socket  104  can then be reversed and resilient member  56  can be installed around proximal section  112  of pin body before the combined pin/socket/resilient member unit can be pressed into insulative member  16  to bring pin head  106  into press-fit engagement with the insulative member. 
         [0047]    In operation, resilient member  56  biases inward socket retainer  116  towards engagement with intermediate projection  108  of pin body  110 . This engagement keeps socket  104  from being pushed out of insulative member  16  by resilient member  56 . As in previously described embodiments, movement of an IC package (not shown) towards insulative member  16  brings electrical contacts of the IC package into contact with socket  104  and compresses resilient member  56 . In this embodiment, pin  98  and socket  104  are sized to produce ‘wiping’ engagement between intermediate projections  108  of pin body  110  and socket body  118  as well as between inward socket retainers  116  and proximal section  112  of the pin body. This wiping engagement provides for a direct electrical path between socket  104  and pin  98  that can be supplemented by a secondary electrical path through resilient member  56 . In some cases, distal section  114  of pin  98  can extend to or slightly past an upper surface  122  of insulative member  16  such that movement of the IC package (not shown) towards the insulative member can bring electrical contacts of the IC package into contact with the distal section of the pin. 
         [0048]    In terminals with socket heads including pointed projections (see  FIGS. 2 and 3 ), the pointed projections can leave ‘witness’ marks or indentations on the ends of the solder balls of BGA packages. In some cases, this can be undesirable because some users perceive such indentations as a possible source or harbor for contamination. Referring to  FIG. 5 , open-ended socket heads  102  can be less likely to leave witness marks and, to the extent that they occur, on the sides rather than bottoms of the solder balls. 
         [0049]    Referring to  FIGS. 6A-9 , in some cases, sockets can include a contact spring, rather than the socket retainers described above. Such contact springs can provide electrical contact between pins and sockets and can also act as a mechanism to keep the sockets in place on the pins. Similarly, in some cases, pins can include a retention feature to aid or replace the press-fit engagement between the insulative member and the pins. 
         [0050]    For example, referring to  FIGS. 6A and 6B , terminal  124  is configured with a double-headed pin  126 , a contact spring socket  128 , and resilient member  56  interposed between the pin and the socket in a substantially similar fashion to terminal  96  illustrated in  FIG. 5  and described above. Double-headed pin  126  includes first pin head  130  with an attached solder ball  50 , a pin body  132  with a proximal section  134  adjacent the first pin head and a distal section  136 , and a enlarged end  138  disposed at an opposite end of the pin body from the first pin head. First pin head  130  includes outwardly extending shoulders  140  and main head section  142 . In this embodiment, proximal section  134  has a larger outer diameter than distal section  136 . The larger size of proximal section  134  provides increased strength and stability to pin  126 . In some embodiments, pin body  132  can have other configurations (e.g., multiple sections, a gradually varying outer diameter, or a single constant outer diameter). Double-headed pin  126  is disposed in insulative member  16  with main head section  142  in press-fit engagement with projections  105  from insulative member  16  and with shoulders  140  engaging a top surface of the projections from the insulative member. Resilient member  56  is disposed with one end engaging shoulders  140  of first pin head  130  and the other end engaging contact spring socket  128 . 
         [0051]    Contact spring socket  128  has a hollow socket body  144  with an open end  146  in which a contact spring  148  is disposed. In this embodiment, contact spring  148  has multiple leaves  150  extending from an annular base  152 . Annular base  152  is disposed at or near open end  146  of socket body  144  with spring leaves  150  extending into the socket body from the base. Spring leaves  150  are biased towards a rest position in which the leaves extend diagonally inwards relative to an inner surface of annular base  152 . Spring leaves  150  are sized and configured such that, in the rest position, the distance between the ends of the leaves that are farthest from base  152  is less than the outer diameter of distal section  136  of pin body  132 . 
         [0052]    Contact spring socket  128  has a socket head  154  with a concave upper surface from which a pointed projection extends. Socket head  154  configures terminal  124  to receive and engage solders balls of a BGA package (not shown). However, use of different socket head configurations allows the use of contact spring sockets with other types of IC packages (e.g., LGA or PGA packages). For example, referring to  FIG. 7 , terminal  156  has contact spring socket  157  with a socket head  158  with a substantially flat upper surface from which a pointed projection extends thus configuring the socket head  158  to receive and engage electrical contacts of an LGA package (not shown). Other elements of terminal  156  are substantially similar to those illustrated in  FIGS. 6A and 6B  and described above. 
         [0053]    Referring to  FIGS. 6A-7 , when terminal  124  and terminal  156  are assembled, distal section  136  and enlarged end  138  of pin  126  are inserted through contact spring  148  into socket body  144 ,  160 . The configuration of contact spring  148  biases spring leaves  150  towards engagement with an outer surface of pin body  132 . At the same time, resilient member  56  biases contact spring socket  128 ,  158  away from first pin head  130 . Engagement between enlarged end  138  of pin  126  and spring leaves  150  keeps contact spring socket  128 ,  157  from being pushed out of insulative member  16  by resilient member  56  (see  FIG. 6A ). 
         [0054]    Referring to  FIGS. 6A-7 , this configuration facilitates installation of terminals  124 ,  156  in insulative member  16 . Pins  126  can be inserted into insulative member  16  until main head sections  142  are press-fit into the insulative member and shoulders  140  engage a top surface of the projections from the insulative member. Resilient members  56  can then be disposed into insulative member  16  around pins  126 . As contact spring sockets  128 ,  157  are then pressed onto pins  126 , enlarged ends  138  of the pins pass through contact spring leaves  150 . After enlarged ends  138  are past contact spring leaves  150 , the bias of the contact spring leaves towards their rest position can maintain ends of the contact springs leaves in contact with pin bodies  132 . 
         [0055]    In operation, these terminals  124 ,  156  function in substantially the same fashion as those embodiments previously described. However, shoulders  140  extending from first pin heads  130  provide an additional mechanism resisting forces applied to pins  126  through contact spring sockets  128 ,  157  and resilient members  56  as an IC package (not shown) approaches circuit board (not shown). This additional mechanism allows for greater tolerances in sizing the holes and pins  126  as the press-fit engagement between first pin heads  130  and insulative member  16  are not alone in keeping these forces from forcing the pins out of the insulative member. Shoulders  140  can also function to keep pins  126  in place as solder balls  50  are reflowed to attach a converter socket assembly to a circuit board. 
         [0056]    In some embodiments, first pin heads  130  and/or insulative member  16  can be deliberately sized to provide for a reduced press-fit engagement between the first pin heads and the insulative member such that it is feasible to replace damaged pins by pulling them out of insulative member  16 . Similarly, contact spring leaves  150  can be configured such that the bias of the spring leaves towards their rest position which provides an engagement with enlarged end  138  of pins  126  which counters the forces applied by the resilient members  56  but allows application of additional force (e.g., by pulling) to remove contact spring sockets  128 ,  157  for replacement. Such replacement can be desirable to replace damaged sockets and/or to reconfigure terminals  124 ,  156  for other electrical contacts. 
         [0057]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, referring to  FIGS. 8 and 9 , some terminals can have solder tails  164  (rather than solder balls) that extend from double-headed pins  166  that are otherwise substantially similar to pins  126  (see  FIGS. 6A-7 ). In some cases, solder tails  164  can be inserted into prepared sockets in a circuit board to provide electrical connections without a need for actual soldering to provide for attachment to the circuit board. In some cases, solder tails  164  can be inserted through thru-holes extending through a circuit board and then reflowed to provide attachment and electrical connection to the circuit board. In another example, contact spring sockets  168  can be configured with open ends  170  for receiving solder balls of BGA packages as described above (see  FIG. 5 ). Referring to  FIG. 9 , such open-ended sockets  168  can be converted for contact with other IC packages by addition of inserted socket heads  172  which is sized such that outer surfaces  174  of the inserted heads can be press-fit into open ends  170  of the sockets. Accordingly, other embodiments are within the scope of the following claims.