Abstract:
An electrical interconnection device including a metal substrate for receiving and holding a plurality of electrical contacts wherein at least one contact is electrically coupled to the substrate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 11/429,800, filed May 8, 2006, which is incorporated herein by reference. 
     
     BACKGROUND 
       [0002]    The present invention relates to electrical interconnection devices having a metal substrate for holding contacts, and to methods for making such interconnection devices. 
         [0003]    Electrical interconnection devices are used to electronically couple components, such as a microprocessor, to a printed circuit board. Typical interconnection devices use multiple metal contacts to transmit electronic signals between the components. Increasing the rate of transmission and decreasing the overall size of the interconnection devices have been ongoing goals of the industry. 
         [0004]    To improve the rate of transmission of these electronic signals, efforts have been made to increase the density of the connections within the interconnection device. In some interconnection devices, injection molded plastic housings are used to receive and support a plurality of electrical contacts. However, the True Position (TP), geometry and co-planarity across the plastic housings are limited by the response and variability of the polymer to the injection molding process. In addition, such plastic housings may be susceptible to shrinkage, warping, bowing and bending. Also, it is beneficial to shield the signal contacts from one another and prevent cross-talk therebetween. However, while these plastic housing structures may isolate the metal contacts from one another, they do not provide shielding. To shield the signal contacts and provide a larger ground path than is typically available in such non-conductive connectors, the plastic housing structures may be metallized or may be equipped with ground planes. Nevertheless, it may be difficult to manufacture plastic housings that meet the demands for increasingly small connectors. The thin walls separating the contacts may be weak and susceptible to breakage. 
         [0005]    As disclosed in disclosed in U.S. Pat. No. 6,945,788 to Trout et al., rigid metal substrate structures have been proposed as an alternative to the plastic housings for supporting the signal contacts. These metal substrate structures may be sized to fit within a plastic housing and include a plurality of apertures sized to receive the signal contacts. The metal substrate structure provides a rigid substrate that is resistant to shrinkage. To insulate the signal contacts from one another and to secure the signal contacts within the apertures, each signal contact may be overmolded with an insulative plastic, which is swaged to the substrate. 
         [0006]    Ungrounded metal or metallized substrates may encounter a “floating ground” or inductive charge from the electrical contacts therein. Accordingly, providing a fixed ground connection for the substrate can lessen or eliminate such a floating ground and inductive charges. 
       SUMMARY 
       [0007]    The present disclosure provides connector apparatuses for interconnecting components and methods for making such connectors. In one form, the present disclosure provides an electrical interconnection device for receiving and holding a plurality of electrical contacts. The electrical interconnection device includes a metal support substrate having an array of contact receiving apertures extending therethrough. Each of the contact receiving apertures is defined by an aperture wall and the contact receiving apertures are adapted to receive the plurality of electrical contacts. The array of contact receiving apertures includes a first and second subset of apertures. The first subset of apertures includes a dielectric layer coating the aperture wall for insulating the first subset of electrical contacts from said substrate. The second subset of apertures for receiving a second subset of electrical contacts are provided such that the second subset of electrical contacts are in electrical contact with the substrate. 
         [0008]    In another embodiment of the disclosure, an electrical interconnection device is provided. The interconnection device includes a support substrate formed of metal and having a top surface and an opposing bottom surface. The support substrate includes first and second contact receiving apertures extending therethrough from said top surface to said bottom surface. Each of said first and second contact receiving apertures are defined by an aperture wall. A dielectric layer coats said first aperture wall. First and second electrical contacts are respectively disposed in said first and second contact receiving apertures. The dielectric layer insulates said first electrical contact from said metal, and said second electrical contact is electrically coupled to said metal. 
         [0009]    In another form, the present disclosure provides a method for manufacturing an electrical interconnection device. The method comprises the steps of constructing a metal support substrate having a top surface and an opposing bottom surface; forming a plurality of electrical contact receiving apertures extending through the metal support substrate from the top surface to the bottom surface, each of the plurality of electrical contact receiving apertures being defined by an aperture wall; covering at least one aperture; and coating the aperture wall of each uncovered aperture of the plurality of electrical contact receiving apertures with a dielectric composition. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a top view of a socket connector apparatus according to one embodiment of the present invention; 
           [0012]      FIG. 2  is a side view of a socket connector apparatus of  FIG. 1 ; 
           [0013]      FIG. 3  is a partial, top sectional view of the socket connector apparatus of  FIG. 2  taken along lines  3 - 3 ; 
           [0014]      FIG. 4  is a partial, side sectional view of the socket connector apparatus of  FIG. 1  taken along lines  4 - 4 ; 
           [0015]      FIG. 5  is another partial, side sectional view of the socket connector apparatus of  FIG. 1  taken along lines  5 - 5 ; 
           [0016]      FIG. 6  is a partial, side sectional view of a socket connector apparatus according to another embodiment of the present invention; 
           [0017]      FIG. 7  is a top view of a socket connector apparatus according to another embodiment of the present invention; 
           [0018]      FIG. 8  is a side view of a socket connector apparatus of  FIG. 7 ; 
           [0019]      FIG. 9  is a partial, top sectional view of the socket connector apparatus of  FIG. 8  taken along lines  9 - 9 ; and 
           [0020]      FIG. 10  is a partial, side sectional view of the socket connector apparatus of  FIG. 7  taken along lines  10 - 10 . 
       
    
    
       [0021]    Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. Although the exemplification set out herein illustrates embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the disclosure to the precise forms disclosed. 
       DETAILED DESCRIPTION 
       [0022]    The embodiments hereinafter disclosed are not intended to be exhaustive or limit the disclosure to the precise forms disclosed in the following description. Rather the embodiments are chosen and described so that others skilled in the art may utilize its teachings. 
         [0023]    Referring to  FIGS. 1-5 , electrical interconnection device in the form of socket connector apparatus  10  according to one embodiment of the present invention will now be described. As illustrated in  FIGS. 1-2  and  4 - 5  and described in further detail below, electrical interconnection device is in the form of ball grid array (BGA) socket connector apparatus  10  which may be used to interface or electronically couple a device, such as a microprocessor, with a circuit board. However, although the present invention is exemplified in the context of a BGA socket connector, the present invention is not limited to BGA socket connectors. Rather, the present invention may be adapted for use as any electrical interconnect structure, including, for example, a Land Grid Array (LGA) socket, Column Grid Array (CGA), right angle connectors and backplane connectors. 
         [0024]    As illustrated in  FIGS. 1-2  and  4 - 5 , socket connector apparatus  10  generally includes support substrate  12  and electrical contacts  18  supported in support substrate  12 . Support substrate  12  includes top surface  22 , opposing bottom surface  24  and an array of contact receiving apertures  14  extending through substrate  12  from top surface  22  to bottom surface  24 . Each of contact receiving apertures  14  is defined by aperture wall  20  and is sized to receive one of electrical contacts  18 . Array of contact receiving apertures  14  may be arranged in any pattern and may include any number of apertures  14 . Although the illustrative embodiment of  FIGS. 1-5  show an array of contact receiving apertures, support substrate  12  may include a single contact receiving aperture. 
         [0025]    Turning now to FIGS.  2  and  4 - 5 , support substrate  12  is formed of a plurality of metal layers or sheets  26   a - 26   g  stacked atop and bonded to one another by any suitable method including, for example, that disclosed in U.S. Patent Application Publication No. 2005/0221634, filed as U.S. patent application Ser. No. 10/818,038 on Apr. 5, 2004 in the names of Hilty et al., entitled Bonded Three Dimensional Metal Laminate Structure and Method, assigned to the assignee of the present invention and hereby incorporated by reference. Each of metal layers  26   a - 26   g  is formed of a rigid base metal such as copper, iron, steel, aluminum, tin, nickel, cobalt, titanium, zinc or alloys thereof. Each of metal layers  26   a - 26   g  may be formed of the same or different base metals. In some cases it may be beneficial for top layer  26   a  to be formed of a first metal, while bottom layer  26   g  is formed of a second different metal. For instance, when apparatus  10  is incorporated in a CGA device for connecting a chip to a circuit board, top layer  26   a  may be made of a metal, such as copper, to match the Coefficient of Thermal Expansion (CTE) of a circuit board, while the bottom layer  26   g  may be made of an alloy to match the CTE of a ceramic of the chip. Furthermore, in this particular embodiment, apparatus  10  may be composed of two parts that fit together; the first piece including top layer  26   a  and the second piece including bottom layer  26   g.    
         [0026]    Referring still to FIGS.  2  and  4 - 5 , each of layers  26   a - 26   g  has a thickness t, which may vary depending on the application. For instance, in one exemplary embodiment, thickness t of each of layers  26   a - 26   g  is between about 0.1 mm and 0.3 mm and, therefore, metal substrate  12  has an overall thickness T of between about 0.7 mm and 2.1 mm. Each of layers  26   a - 26   g  includes an array of apertures, which cooperate with one another when layers  26   a - 26   g  are properly aligned and stacked atop one another to form contact receiving apertures  14 . Each of layers  26   a - 26   g  may include alignment features such as indents, slots, points, pips, barbs or apertures (not shown) to facilitate the proper alignment and stacking of layers  26   a - 26   g . Layers  26   a - 26   g  may be formed by known means including, for example, chemical etching or die stamping. 
         [0027]    It should be understood that, although support substrate  12  is illustrated as having seven metal layers  26   a - 26   g , the support substrate of the present invention may have any number of layers. Further, each of layers  26   a - 26   g  need not be of equal thickness, but may vary in thickness. In addition, the overall thickness of substrate  12  may vary. It should also be understood that support substrate  12  may be formed of a single metal layer, rather than a laminate of multiple metal layers, as shown in  FIG. 6  and discussed in further detail below. In addition, each metal layer need not be of the same geometry. Rather, the layers could include various geometrical variations such as steps, shoulders, pockets or holes. In addition, support substrate, particularly top and bottom surfaces  22 ,  24  and/or aperture wall  20  of apertures  14 , may include barbs, ridges, bumps or other surface texture features to assist in the binding of dielectric layer  16  to support substrate  12 . 
         [0028]    Referring still to  FIGS. 3-5 , socket connector apparatus  10  also includes dielectric layer  16 , which coats and insulates aperture wall  20 . Dielectric layer  16  may also extend outwardly from aperture  14  to coat all or a portion of top and bottom surfaces  22 ,  24  of support substrate  12 . Dielectric layer  16  is formed of a dielectric material capable of insulating metal support substrate  12  from contact  18  disposed in aperture  14 . As discussed in further detail below, the dielectric material should also be durable enough to resist penetration by contact  18  when contact  18  is loaded into aperture  14 . Suitable dielectric materials may include ceramics, glass and plastics, including both thermoset polymers and thermopolymers. Suitable dielectric materials may be in any form including powder, liquid and/or gas and, if necessary, may be cured using any suitable means, such as heat, radiation and catalysts. For example, thermoplastic resin powder coatings suitable for use as a dielectric material may include polyamide, polyester, polyether-ether-ketone (PEEK), polypropylene, polyethylene and fluoropolymers. In one particular embodiment, the dielectric material is Scotchcast™ Electrical Resin 5230N, an epoxy resin available from 3M of St. Paul, Minn. Additional examples of suitable commercially available thermoplastic powder coating materials include Rohm &amp; Haas polyamides and polyesters, Victrex PEEK, and Hyflon fluoropolymers from Solvay Solexis. Examples of suitable commercially available thermosetting powder coatings include Stator Red epoxy from DuPont, Resicoat epoxy from Akzo Nobel, Mor-Temp silicone from Morton International, and Torlon polyamide-imide from Solvay. 
         [0029]    The dielectric material may be applied to support substrate  12  using any suitable coating techniques including, for example, electrostatic fluidized bed methods, liquid dip coating methods, electrodeposition methods, vapor deposition methods, overmolding and spray coating. In one particular embodiment, the Scotchcast™ Electrical Resin 5230N is applied using an electrostatic fluidized bed method. Dielectric layer  16  has a thickness t d , which may vary depending on the size and structure of contact  18  and aperture  14 . In one particular embodiment, dielectric layer  16  has a thickness t d  of between about 0.075 mm to 0.125 mm (0.003 inches-0.005 inches). 
         [0030]    As suggested above, the dielectric material may be applied to aperture wall  20  of each of apertures  14  such that dielectric layer  16  coats aperture wall  20 . The dielectric material may also be applied to a portion of top and/or bottom surfaces  22 ,  24  of support substrate  12  proximal apertures  14  to provide further insulation between contact  18  and metal support substrate  12 . The efficiency of the manufacture of connector apparatus  10  may be further improved by avoiding the selective application of the dielectric material to aperture wall  20  and a portion of top and bottom surfaces  22 ,  24  and, instead, applying the dielectric material to all exposed surfaces of support substrate  12  including aperture wall  20  and top and bottom surfaces  22 ,  24 . It should be understood that aperture wall  20  of every one of the plurality of apertures  14  need not be coated. For instance, as discussed below with respect to  FIGS. 7-10 , it may be desirable to only coat a selected one or few of apertures  14 , in which case, those apertures  14  not requiring dielectric layer  16  may be plugged during the application of the dielectric material. 
         [0031]    Referring now to  FIGS. 4-5 , each of contacts  18  are formed of a conductive metal such as copper, iron, steel, aluminum, tin, nickel, cobalt, titanium, zinc or alloys thereof. Each of contacts  18  includes resilient body portion  36 , which is configured to fit within coated aperture  14  and is adapted to bias outwardly against aperture wall  20  to thereby hold body  36  within aperture  14  by interference fit. More specifically, body  36  is in the form of an eye-of-the-needle contact. Each of contacts  18  also include upper ball contact  38  extending from one end of body  36  and protruding from aperture  14  proximal top surface  22  of support substrate  12 . Lower pin contact  40  extends from the end of body  36  opposite upper contact  38  and protrudes from aperture  14  proximal bottom surface  24  of support substrate  12 . Although contacts  18  of the exemplary embodiment are illustrated in  FIGS. 1-6  and described above as eye-of-the-needle ball contacts, the present invention may employ any known contact design. 
         [0032]    Contacts  18  are directly loaded into coated apertures  14  by inserting lower pin contact  40  through, and forcing body  36 , into aperture  14 . As body  36  is positioned in aperture  14 , body  36  biases and scrapes against dielectric layer  16 , but does not penetrate dielectric layer  16 . Once inserted into aperture  14 , body  36  is held by interference fit against dielectric layer  16  in aperture  14 . 
         [0033]    Metal support substrate  12  provides connector apparatus  10  with a rigid and stable support structure that resists bending and bowing, while dielectric layer  16  insulates contact  18  from metal support substrate  12 . Dielectric layer  16  also eliminates the need for overmolding or coating contacts  18  prior to loading in apertures  14 , and allows contact  18  to be directly loaded into apertures  14 . 
         [0034]    Turning now to  FIG. 6 , connector apparatus  110  according to another embodiment of the present invention is illustrated. Connector apparatus  110  includes support substrate  112 , which is formed of a single metal layer rather than multiple layers. Apertures  114  extend through substrate  112  and receive contacts  118 . Apertures  114  are coated with dielectric layer  116  as described above with respect to connector apparatus  10 . The single metal layer of support substrate  112  may be formed by known means including, for example, chemical etching or die stamping. 
         [0035]    Referring to  FIGS. 7 ,  8 , electrical interconnection device in the form of socket connector apparatus  210  according to another embodiment of the present invention will now be described. Electrical interconnection device is in the form of land grid array (LGA) socket connector apparatus  210  which may be used to interface or electronically couple a device, such as a microprocessor, with a circuit board. However, although the present invention is exemplified in the context of an LGA socket connector, the present invention is not limited to LGA socket connectors. Rather, the present invention may be adapted for use as any electrical interconnect structure, including, for example, a Ball Grid Array (BGA) socket, Column Grid Array (CGA), right angle connectors and backplane connectors. 
         [0036]    As illustrated in  FIGS. 7-10 , socket connector apparatus  210  generally includes support substrate  212  and electrical contacts  218  supported in support substrate  212 . Support substrate  212  includes top surface  222 , opposing bottom surface  224  and an array of contact receiving apertures  214  extending through substrate  212  from top surface  222  to bottom surface  224 . Each of contact receiving apertures  214  is defined by aperture wall  220  and is sized to receive one of electrical contacts  218 . Array of contact receiving apertures  214  may be arranged in any pattern and may include any number of apertures  214 . Although the illustrative embodiment of  FIGS. 7-10  shows an array of contact receiving apertures  214 , support substrate  212  may include a single contact receiving aperture  214 . 
         [0037]    Turning now to  FIGS. 8 and 10 , support substrate  212  is formed from a single metal layer. Embodiments are also envisioned where substrate  212  is formed of a plurality of metal layers or sheets stacked atop and bonded to one another by any suitable method as discussed above. Additionally, while substrate  212  is described as metal, embodiments are also envisioned that utilize metal coated plastic, metal impregnated plastic, or any other conductive material. 
         [0038]    Referring still to  FIGS. 9 ,  10 , socket connector apparatus  210  also includes dielectric layer  216 , which coats and insulates aperture wall  220 . Dielectric layer  216  is similar to dielectric layer  16  and may also extend outwardly from aperture  214  to coat all or a portion of top and bottom surfaces  222 ,  224  of support substrate  212 . As discussed in further detail below, the dielectric material should also be durable enough to resist penetration by contact  218  when contact  218  is loaded into aperture  214 . 
         [0039]    The dielectric material may be applied to support substrate  212  using any suitable coating technique including, for example, electrostatic fluidized bed methods, liquid dip coating methods, electrodeposition methods, vapor deposition methods, overmolding and spray coating. In one particular embodiment, the Scotchcast™ Electrical Resin 5230N is applied using an electrostatic fluidized bed method. Dielectric layer  216  has a thickness which may vary depending on the size and structure of contact  218  and aperture  214 . In one particular embodiment, dielectric layer  216  has a thickness of between about 0.075 mm to 0.125 mm (0.003 inches-0.005 inches). 
         [0040]    As suggested above, the dielectric material may be applied to aperture wall  220  of each of apertures  214  such that dielectric layer  216  coats aperture wall  220 . The dielectric material may also be applied to a portion of top and/or bottom surfaces  222 ,  224  of support substrate  212  proximal apertures  214  to provide further insulation between contact  218  and metal support substrate  212 . It should be understood that aperture wall  220  of every one of the plurality of apertures  214  need not be coated. As shown in  FIG. 10 , selected one aperture  214   a , or more than one of apertures  214 , is not coated with dielectric layer  216 . Aperture  214   a  is plugged or masked during the application of the dielectric layer  216 . Accordingly, metal substrate  212  is exposed within aperture  214   a . This selective coating and exposure separates apertures  214 ,  214   a  into first and second subsets of apertures. Aperture(s)  214  of the first subset is/are coated with dielectric layer  216  and aperture(s)  214   a  of the second subset is/are exposed. 
         [0041]    Referring now to  FIG. 10 , each of contacts  218  are formed of a conductive metal such as copper, iron, steel, aluminum, tin, nickel, cobalt, titanium, zinc or alloys thereof. Each of contacts  218  includes resilient body portion  236  which is configured to fit within coated aperture  214  and is adapted to bias outwardly against aperture wall  220  to thereby hold body  236  within aperture  214  by interference fit. More specifically, body  236  is in the form of an eye-of-the-needle contact. Each of contacts  218  also includes upper pin contact  238  extending from one end of body  236  and protruding from aperture  214 ,  214   a  proximal top surface  222  of support substrate  212 . Lower pin contact  240  extends from the end of body  236  opposite upper pin contact  238  and protrudes from aperture  214 ,  214   a  proximal bottom surface  224  of support substrate  212 . Although contacts  218  of the exemplary embodiment are illustrated in  FIGS. 7-10  and described above as eye-of-the-needle contacts, the present invention may employ any known contact design. 
         [0042]    Contacts  218  are directly loaded into apertures  214 ,  214   a  by inserting lower pin contact  240  through, and forcing body  236 , into aperture  214 ,  214   a . As body  236  is positioned in aperture  214 , body  236  biases and scrapes against dielectric layer  216 , but does not penetrate dielectric layer  216 . Likewise, as body  236  is positioned in aperture  214   a , body  236  biases and scrapes against wall  220 . Once inserted into aperture  214 ,  214   a , body  236  is held by interference fit against dielectric layer  216  in aperture  214 , and against wall  220  in aperture  214   a.    
         [0043]    Metal support substrate  212  provides connector apparatus  210  with a rigid and stable support structure that resists bending and bowing, while dielectric layer  216  insulates contact  218  from metal support substrate  212 . Dielectric layer  216  also eliminates the need for overmolding or coating contacts  218  prior to loading in apertures  214 , and allows contact  218  to be directly loaded into apertures  214 . 
         [0044]    The interference fit of body  236  to wall  220  in aperture  214   a  electrically couples body  236  and substrate  212 . Aperture  214   a  is chosen such that body  236  received therein corresponds to system ground contacts of the associated printed circuit board and chip. Accordingly, when assembled, substrate  212  is electrically grounded to system ground. Such grounding provides a matched impedance for adjacent contacts. Furthermore, dielectric layer  216  insulates other bodies  236  from grounded substrate  212 . 
         [0045]    While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.