Patent Publication Number: US-2007111578-A1

Title: Socket adapter mold

Description:
TECHNICAL FIELD  
      This invention relates to intercoupling components of the type 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, and more particularly to a mold and method for manufacturing a mold for forming such intercoupling components.  
     BACKGROUND  
      Intercoupling components of the type 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 can be formed of an insulative member with apertures in which electrical terminals such as pins and sockets are inserted. Such insulative members can be molded of thermoplastics in electric or hydraulic mold presses. Mold inserts associated with this process can be formed by machining metal blocks to receive pins at locations corresponding to the desired locations of the apertures.  
     SUMMARY  
      One aspect of the invention features a method of manufacturing a mold for forming an intercoupling component of the type 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 method includes providing a plurality of plates, each plate including an array of holes arranged in a pattern corresponding to the array of electrical connection regions of the first substrate; forming a base by stacking the plates with the holes substantially aligned; inserting pins into apertures formed in the base by the aligned holes; and assembling a housing with the base, pins, at least one sidewall, and a cover, the housing including a substantially enclosed cavity, the housing also including at least one opening to enable injection of molten material into the cavity.  
      Another aspect of the invention features a mold for forming an intercoupling component of the type 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 mold includes a base, at least one sidewall, and a cover, which together define a substantially enclosed cavity, at least one of the base, at least one sidewall, and cover including at least one opening to enable injection of molten material into the cavity; and pins extending from the base into the mold cavity, the pins having first ends received by the base and second ends contacting an interior surface of the cover. The base includes a plurality of plates, each plate having an array of holes arranged in a pattern corresponding to the array of electrical connection regions of the first substrate.  
      In some embodiments, each plate has a first thickness between about 0.010 inch (0.254 millimeter) and 0.014 inch (0.356 millimeters). In some instances, the base has a second thickness between about 0.20 inch (5.1 millimeters) and 0.70 inch (18 millimeters). Each plate can include stainless steel.  
      In some embodiments, forming the base comprises stacking between about 10 and 100 plates (e.g., between about 20 and 50 plates). The plurality of plates can be stacked with the arrays of holes substantially aligned. The aligned arrays of holes can form arrays of apertures receiving the pins. Each of the holes can have a diameter of between about 0.009 inch (0.229 millimeter) and 0.012 inch (0.305 millimeter). The array of holes can include a first sub-array of holes and a second sub-array of holes. In some instances, each of the first sub-array of holes has a first diameter and each of the second sub-array of holes has a second diameter that is less than the first diameter. In some instances, a first subset of core pins is received by the first sub-array of holes and a second subset of core pins is received by the second sub-array of holes, the first subset of core pins having first diameter in the mold cavity that is greater than a second diameter of the second subset of core pins in the mold cavity.  
      In some embodiments, providing the plates can include machining the plates to form the array of holes with a pitch of between about 0.012 inch (0.3 millimeter) and 0.031 inch (0.8 millimeter). Providing the plates can feature forming the array of holes by laser machining each plate. Providing the plates can also feature forming the array of holes with diameters between about 0.009 inch (0.229 millimeter) and 0.012 inch (0.305 millimeter).  
      In some embodiments, assembling the base and pins with the at least one sidewall, and cover includes contacting an interior surface of the cover with distal ends of the pins.  
      In some embodiments, each core pin includes a distal end contacting the interior surface of the cover, the distal end having a substantially planar surface such that contact between the distal end and the interior surface of the cover inhibits the flow of molten material between the distal end and the interior surface.  
      Manufacturing a mold as provided for by the various aspects of the invention can provide several advantages. In general, such methods can be used to efficiently produce molds of the type used for forming an intercoupling component of the type 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 (e.g., a socket adapter mold). More particularly, such methods can produce molds with a small (e.g., below 0.8 millimeters or about 0.5 millimeters) between adjacent core pins which are located with a high degree of precision. Providing such molds can enable the production of intercoupling components such as socket adapters with increased terminal density and reduced overall size.  
      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  
       FIG. 1  is a perspective view of a body of a socket adapter.  
       FIG. 2  is a side view, partially cutaway, of a mold for producing the socket adapter body shown in  FIG. 1 .  
       FIGS. 3A and 3B  are, respectively, an exploded side view and perspective view of a portion of the mold shown in  FIG. 2 .  
       FIGS. 4 and 5  are plan views of core pins retaining plates of the mold shown in  FIG. 2 .  
       FIGS. 6 and 7  are side views of core pins of the mold shown in  FIG. 2 .  
       FIG. 8  is a flow chart of a method of forming the mold shown in  FIG. 2 . 
    
    
      Like reference symbols in the various drawings indicate like elements. Terms such as top and bottom are used for clarity of description to note the relative location of elements on the figures rather than to imply absolute relationships between such elements.  
     DETAILED DESCRIPTION  
      Referring to  FIG. 1 , a body  10  of a socket adapter is molded of thermoplastic resin (e.g., FR-4). Body  10  includes a peripheral region  12  and a central region  14 . Peripheral region  12  is substantially solid and provides structural support to central region  14  which contains multiple apertures  16  that extend through body  10 . Apertures  16  are sized and configured to receive terminal elements (not shown) of the socket adapter. Such terminal elements are adapted to provide electrical and mechanical connections between electrical components such as, for example, printed circuit boards, pin grid array (PGA) circuit packages, and ball grid array (BGA) circuit packages. For example, embodiments of such terminal elements are described in detail in U.S. Pat. No. 6,313,530, the contents of which are incorporated herein by reference in their entirety. In the illustrative embodiment, peripheral regions  12  of body  10  also include knockout holes  18  that are artifacts of the molding process used to make the socket adapter body.  
      As electrical components increase in complexity, the desired density of such terminal elements on socket adapters also increases. The corresponding increased desired density of apertures  16  in such socket adapters requires a decrease in the pitch or spacing between adjacent apertures  16 . To date, the minimum pitch achievable has been limited by factors including the machining techniques used to produce the molds used to form bodies  10 . An innovative mold production technique, as described in detail below, can be used to produce bodies  10  of socket adapters with apertures  16  set at a pitch of less than about 0.8 millimeters (e.g., 0.5 millimeters). This mold production technique can also be used to efficiently produce larger pitch molds.  
      Referring to  FIGS. 2, 3A , and  3 B, an illustrative mold  20  includes an A-side  22  and a B-side  24  whose components are configured for interlocking engagement. A-side  22  and B-side  24  each include a main mold body  28 A,  28 B and a knockout system  30 . Outer surfaces  26  of mold  20  are sized to standard specified dimensions for a specific electric or hydraulic mold press. As discussed above, various embodiments of mold  20  are used to produce bodies  10  for various socket adapters. Using standard specified outer dimensions facilitates switching out embodiments of mold  20  installed in a hydraulic mold press because the main mold bodies  28 A,  28 B are sized and configured to act as quick change cavity inserts.  
      Main mold bodies  28 A,  28 B are essentially mirror images of each other. The primary difference is that main mold body  28 A of A-side  22  includes locating pins  48  while main mold body  28 B of B-side  24  includes cavities  50  sized and located to receive the locating pins. Main mold bodies  28 A,  28 B each include a mold plate  52 , a mold cavity retainer  58 , and a backing plate  68 . Mold plate  52  defines a plate cavity  54  which is sized and located to receive core pin retaining plates  56 . A mold cavity retainer  58  is attached to mold plate  52  with screws (not shown). Mold cavity retainer  58  holds core pin retaining plates  56  in plate cavity  54  and defines a mold cavity  40 .  
      Screws are used to attach the various pieces of the illustrative embodiment to each other and are also used to attach mold  20  to a hydraulic mold press. However, for clarity of illustration, the screws and bores which receive them are not shown.  
      Core pin retaining plates  56  are stainless steel plates with pin holes  60  through which core pins  42  are inserted with their ends extending into and through mold cavity  40 . In other embodiments, core pin retaining plates  56  can be manufactured from other materials including, for example, tool-hardened steel. Core pins  42  are located in an array (e.g., a 25×25 array) with interstitial spaces separating adjacent core pins. Mold cavities  40  are individually open on their interior sides, but when A-side  22  and B-side  24  are assembled and placed together, the open interior sides of the two mold cavities face each other such that the two mold cavities in effect define a single cavity that is substantially enclosed with the exception of a runner  78  ( FIG. 3B ) that provides an aperture through which moldable material is injected into the mold cavity. When A-side  22  and B-side  24  are assembled, core pins  42  of each side fit into the interstitial spaces separating adjacent core pins of the other side and contact the top core pin retaining plate  56  of the other side. Thus, combined mold cavities  40  contain core pins  42  at locations corresponding to the desired locations of apertures  16  of socket adapter body  10 . The minimum pitch of apertures  16  of socket adapter body  10  is governed in part by the degree of accuracy that can be achieved in placing and machining pin holes  60  in core pin retaining plates  56 .  
      Referring to  FIGS. 4 and 5 , core pin retaining plates  56 A of A-side  22  are thin stainless steel plates with core pin holes  60 , locating pin holes  74 , and knockout pin holes  76 A. Core pin retaining plates  56 B of B-side  24  are similar thin stainless steel plates but also include knockout pin holes  76 B for receiving smaller knockout pins  32 B. These stainless steel plates are approximately 0.012 inch in thickness, which allows efficient and precise machining of these holes, particularly core pin holes  60 , using laser machining processes. For example, a plate can be designed with a particular arrangement of core pin holes  60  to provide a socket adapter body with a corresponding arrangement of apertures using computer-aided design software. The design can be exported from the computer-aided design software and used as data by a computer-controlled laser machining tool (e.g., a CNC machining tool). Using this approach, core pin holes  60  with a pitch of less than about 0.8 millimeters (e.g., 0.5 millimeters) can be machined with positional and machining tolerances of less than about 0.0005 inch. This is more precise than can be achieved using drilling techniques required to machine holes in thicker pieces of stainless steel.  
      Referring to  FIGS. 6 and 7 , although core pins  42 A for A-side  22  and core pins  42 B for B-side  24  have slightly different configurations, both configurations include a shoulder  62  between a relatively thicker base end  64  and a relatively thinner pin end  66 . The dimensions of base ends  64  and pin ends  66  of core pins  42  are chosen such that the pin ends fit through pinholes  60  while the base ends do not. This is important in the assembly of mold  20  as described below.  
      Referring again to  FIG. 2 , assembly of mold  20  is described. Each of the cutaway portions in  FIG. 2  show a cross-sectional view of the interior of an element of mold  20  taken along the centerline of the particular element. As can be seen in the cutaway portion of mold plate  52 A of A-side  22 , locating pins  48  have heads  70  at the ends of stems  72 . Mold plate  52 A includes apertures extending through the mold plate which receive locating pins  48 . Locating pins  48  are placed in these apertures with their heads  70  and a portion of their bodies  72  received within the apertures and a portion of their bodies extending outward from mold plate  52 A. After locating pins  48  are placed in these apertures, backing plate  68  is attached to mold plate  52 A, thus locking the locating pins into place.  
      After locating pins  48  are installed in main mold body  28 A, the main mold body is placed with the locating pins and cavity  54  in mold plate  52  facing upwards. Core pin retaining plates  56  are then stacked in cavity  54  in mold plate  52  with locating pins  48  inserted through locating pin holes  74  in each core pin retaining plate. By providing two fixed reference points, locating pins  48  provide an efficient means of aligning core pin holes  60  in the stack of core pin retaining plates  56 . After core pin retaining plates  56  are placed in cavity  54 , mold cavity retainer  58  is attached to mold plate  52 A. Main mold body  28 A is placed so that backing plate  68  now faces upwards. Backing plate  68  is removed, thus exposing aligned core pin holes  60  for manual insertion of core pins  42 A into core pin retaining plates  56 . After core pins  42 A are inserted, backing plate  68  is attached to mold plate  52 A thus locking locating pins  48  and core pins  42 A into place.  
      As described above, core pin holes  60  can be machined in core pin retaining plates  56  with a high degree of precision partly because the plates are thin. This precise location of core pin holes  60  is complemented by the alignment of the core pin holes on stacked core pin retaining plates  56  provided by locating pins  48 . The stacks of core pin retaining plates  56  can thus hold core pins  42 A,  42 B in place with a similar degree of rigidity as a solid block.  
      Main mold body  28 A is then placed with mold cavity retainer  58  and extended locating pins  48  facing upwards. Mold cavity retainer  58  of B-side  24  is placed on top of A-side  22  with locating pins  48  extending through the B-side mold cavity retainer. Core pin retaining plates  56  and mold plate  52 B of B-side  24  are then placed on top of mold cavity retainer  58 . After mold cavity retainer  58  is attached to mold plate  52 B, core pins  42 B are manually installed and backing plate  68  is attached to mold plate  52 B. As can be seen on the cutaway portion of main mold body  28 B, shoulders  62  of core pins  42 B engage the bottommost core pin retaining plate  56 . Thus, when backing plate  68  is attached to mold plate  52 , the backing plate holds core pins  42 B in place.  
      Knockout pins  32 A,  32 B of knockout systems  30  extend from a two-piece block  34 . Four larger knockout pins  32 A are generally located towards the comers of two-piece plot  34 . As can be seen in the cutaway portion of the upper two-piece block  34 , larger knockout pins  32 A include a head  44  at the end of the stem  46 . The outer dimensions of heads  44  are larger than the outer dimensions of stems  46 . For example, in the illustrative system, heads  44  and stems  46  of larger knockout pins  32 A have diameters of about 0.066 inch and 0.046 inch, respectively. In this embodiment, seventeen smaller knockout pins  32 B are located around the perimeter of a mold cavity  40  into which core pins  42  extend and have similar heads and stems.  
      Each two-piece block  34  has an interior portion  36  and an exterior portion  38  attached to each other with the interior portion located on the side of the two-piece block facing towards an adjacent main mold body  28 A,  28 B. Interior portion  36  includes apertures extending through the interior portion but are sized and located to receive knockout pins  32 A,  32 B. Knockout pins  32 A,  32 B are placed in the apertures with their heads  44  and a portion of their bodies  46  received within the apertures a part of their bodies extend outward from the apertures. End surfaces of heads  44  are aligned with adjacent surfaces of interior portion  36 . After knockout pins  32 A,  32 B are placed in the apertures, exterior portion  38  is attached to interior portion  36 , thus locking the knockout pins into place. Although the illustrative embodiment of the knockout system is easily manufactured and assembled, other approaches to providing a similar mechanism can also be used.  
      Referring to  FIG. 8 , assembly of the mold thus includes providing a plurality of plates, each plate including an array of holes arranged in a pattern corresponding to the array of electrical connection regions of a first substrate (step  110 ). A base is formed by stacking the plates with the holes substantially aligned (step  112 ). Pins are inserted into apertures formed in the base by the aligned holes (step  114 ). Finally a housing is assembled with the base, pins, at least one sidewall, and a cover, the housing including a substantially enclosed cavity, the housing also including at least one opening to enable injection of molten material into the cavity (step  114 ).  
      Each plate can have a first thickness between about 0.010 inch (0.254 millimeter) and 0.014 inch (0.356 millimeters). The plates can be made of stainless steel. Providing the plates can include forming the array of holes by laser machining each plate, particularly, machining the plates to form the array of holes with a pitch of between about 0.012 inch (0.3 millimeter) and 0.031 inch (0.8 millimeter), more particularly, with diameters between about 0.009 inch (0.229 millimeter) and 0.012 inch (0.305 millimeter).  
      The base can have a second thickness between about 0.20 inch (5.1 millimeters) and 0.70 inch (18 millimeters). Forming the base can include stacking between about 10 and 100 plates, more particularly stacking between about 20 and 50 plates.  
      Assembling the base and pins with the at least one sidewall, and cover can include contacting an interior surface of the cover with distal ends of the pins.  
      In one example, an alternate embodiment of a mold was assembled substantially as described above with the exception that only the B-side had an associated knockout system. The mold was sized and configured for use with a Nissei Electric NEX 500 mold press and the main mold bodies had exterior dimensions of approximately 3.5 inch×5 inch×2.6 inch. In a given operational cycle, the mold press injects molten Liquid Crystal Polyester (LCP) thermoplastic into the mold cavity through the runner defined in the surfaces of the mold cavity retainers and applies between approximately 5.75 pounds per square inch (e.g., between about 525 and 625 pounds per square inch) of pressure to hold the A-side and B-side together for approximately 8 seconds to allow the LCP thermoplastic to set. Sides of the mold press are separated and pressure is applied to the knockout system to force the socket adapter body from the mold thus allowing the manufactured socket adapter mold to fall into a collection bin underneath the mold press. The manufactured socket adapter body has an 25×25 array of apertures with a pitch of approximately 0.5 millimeters.  
      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, one alternate embodiment only includes one knockout system. Accordingly, other embodiments are within the scope of the following claims.