Abstract:
A method and associated structure for forming a conductive path within a laminate. A conductive element is presses into an opening in the laminate such that portion of at least one end of the conductive element extends beyond a surface of the laminate. A compressive pressure is applied to the portion of the at least one end of the conductive element. The compressive pressure applied to the at least one end of the conductive element forms a contact pad extending beyond the surface of the laminate. The conductive element may include an inner element covered by an outer element.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to a method of embedding a conductive object in a layer of a circuit board. 
   2. Related Art 
   A connection between layers of a circuit board is produced by utilizing a conductive paste in a hole or by a plated through hole (PTH). Conductive pastes can create reliability issues. The conductive pastes can chemically degrade and build resistance as the circuit board is repeatedly heated and cooled. Additionally, the PTH consumes valuable space on all of the layers that it passes through. 
   SUMMARY OF THE INVENTION 
   A first general aspect of the present invention provides a method comprising: 
   providing a laminate with a top surface and a bottom surface and having at least one hole; 
   providing a conductive element; 
   inserting the conductive element into the at least one hole in the laminate; and 
   deforming the conductive element within the at least one hole in the laminate to retain the conductive element within the at least one hole. 
   A second general aspect of the present invention provides a method comprising: 
   embedding a conductive element into a laminate, wherein the conductive element substantially maintains a shape while the laminate deforms to accommodate the conductive element. 
   A third general aspect of the present invention provides a method comprising: 
   providing an opening in a laminate; and 
   pressing a conductive element into the opening. 
   A fourth general aspect of the present invention provides a method comprising: 
   providing a plurality of laminates; 
   embedding at least one conductive element into each laminate; 
   forming a contact pad on each end of each conductive element; 
   bonding each laminate together to form a stack; and 
   wherein adjoining contact pads press together and form an electrical connection. 
   A fifth general aspect of the present invention provides a structure comprising: 
   a conductive element embedded into a laminate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For an understanding of the present invention, reference should be made to the following detailed description taken in connection with the accompanying drawings wherein: 
       FIG. 1  illustrates a laminate structure including a laminate, a conductive inner plane, an opening and a conductive element; 
       FIG. 2  illustrates a deformed conductive element filling the opening in the laminate; 
       FIG. 3  illustrates another embodiment of a conductive element including an electrode or contact pad of the conductive element formed at a top surface of a laminate and a conductive inner plane; 
       FIG. 4  illustrates another embodiment of a conductive element filling a through hole in a laminate; 
       FIG. 5  illustrates another embodiment a conductive element including a cylindrical shape and a conductive inner plane; 
       FIG. 6  illustrates the conductive element of  FIG. 5  including a contact pad formed on a top surface and a bottom surface of a laminate; 
       FIG. 7  illustrates another embodiment of a conductive element including a cylindrical element filling a through hole in a laminate; 
       FIG. 8  illustrates another embodiment of a conductive element including a conductive surface covering a base element; 
       FIG. 9  illustrates another embodiment of a conductive element filling a blind via in a stack of laminates; 
       FIG. 10  illustrates another embodiment of a conductive element as the conductive element is projected towards a laminate; 
       FIG. 11  illustrates the conductive element of  FIG. 10  pressed into the laminate of  FIG. 10 ; 
       FIG. 12  illustrates stack including a plurality of laminates with each laminate including a conductive element; and 
       FIG. 13  illustrates the laminates of  FIG. 12  forming a stack including having the conductive elements in electrical contact. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a laminate  10  including an opening  12  and a conductive element  14 . The opening  12  may be any suitable shape (e.g., a hole, an oval, a square, etc.). The laminate  10  may comprise any suitable material (e.g., epoxy, cyanate-epoxy blends, glass reinforced carrier, etc.) The conductive element  14  is pressed into the opening  12 . The conductive element  14  may comprise any suitable conductive material (e.g., copper, brass, gold, bronze, etc.). The conductive element  14  may be any suitable shape (e.g., sphere, cylinder, etc.).  FIG. 1  illustrates the conductive element  14  in the shape of a sphere. The conductive element  14  is pressed into the opening  12  in the laminate  10 . The conductive element  14  may deform to fill the opening as illustrated in  FIG. 2 . Additionally, the opening  12  in the laminate  10  may deform to conform to the shape of the conductive element  14 . A conductive inner plane  15 C is connected to the outside of the laminate through the conductive element  14 . A top surface  16  of the conductive element  14  may deform to be substantially flush with a top surface  18  of the laminate  10  ( FIG. 2 ). 
     FIG. 3  illustrates another embodiment of a conductive element  14 A pressed into the opening  12  in the laminate  10 . The conductive element  14 A fills the opening  12  and includes an electrode or contact pad  20  that extends above the top surface  18  of the laminate  10 . The conductive inner plane  15 C is connected to the outside of laminate  10  through the conductive element  14 A. 
     FIG. 4  illustrates another embodiment of a conductive element  14 B pressed into an opening  12 B of a laminate  10 B. The opening  12 B extends through the laminate  10 B from a top surface  18 B to a bottom surface  22 B of the laminate  10 B. The conductive element  14 B includes a contact pad  20 B extending above the top surface  18 B of the laminate  10 B. Additionally, the conductive element  14 B includes a contact pad  20 C that extends below the bottom surface  22 B of the laminate  10 B. 
     FIG. 5  illustrates another embodiment of a conductive element  14 C pressed into an opening  12 C of a laminate  10 C. The conductive element  14 C is cylindrical in shape. The conductive element  14 C fills the opening  12 C and extends above conductive pad  15 D and below a bottom surface  22 C of the laminate  10 C. A conductive pad  15 D is formed on the top surface  18 C. Compressive pressure is applied to a top surface  24  and to a bottom surface  26  of the conductive element  14 C. The top surface  24  of the conductive element  14 C deforms and forms the contact pad  20 D as illustrated in  FIG. 6 . The bottom surface  26  of the conductive element  14 C deforms and forms the contact pad  20 E. The contact pads  20 D and  20 E extend beyond the opening  12 C and prevent the conductive element  14 C from slipping out of the opening  12 C in the laminate  10 C. 
     FIG. 7  illustrates another embodiment of a conductive element  14 D pressed into an opening  12 D of a laminate  10 D. The conductive element  14 D is cylindrical in shape. The conductive element  14 D may be solid or hollow. A top surface  24 D of the conductive element  14 D is flush with a top surface of the conductive pad  15 D of laminate  10 D and a bottom surface  26 D of the conductive element  14 D is flush with a bottom surface  22 D of the laminate  10 D. 
     FIG. 8  illustrates another embodiment of a conductive element  14 E. The conductive element  14 E includes a conductive surface  28  covering a base element  30 . The conductive element  14 E may include any suitable shape (e.g., sphere, cylinder, oval, etc.). The conductive surface  28  may include any suitable conductive material (e.g., copper, brass, gold, bronze, etc.). The base element  30  may include any suitable material (e.g., glass, rubber, plastic, etc.). 
     FIG. 9  illustrates another embodiment of a conductive element  14 F included in a stack  32 . The stack  32  includes a plurality of laminates  10 E,  10 F,  10 G and conductive pad or traces  15 A and  15 B. The stack  32  includes a buried via opening  34 . The buried via opening  34  is filled with a conductive element  14 F. The stack  32  is formed by drilling the buried via opening  34  in the laminate  10 F. The conductive element  14 F is pressed into the buried via opening  34 . Next, the laminates  10 E and  10 G are bonded to the laminate  10 F forming the stack  32 . 
     FIG. 10  illustrates another embodiment of a conductive element  14 G. The conductive element  14 G is projected towards the top surface  18 H of the laminate  10 H. The conductive element  14 G impacts the top surface  18 H of the laminate  10 H and embeds itself into the laminate  10 H as illustrated in  FIG. 11 . Conductive inner plane  15 C is connected to the outside of the laminate  10 H through conductive element  14 G. 
     FIG. 12  illustrates another embodiment of a stack  32 A including a conductive element  14 I, a conductive element  14 J, a laminate  10 I, and a laminate  10 J. The conductive element  14 I is pressed into an opening  12 I in the laminate  10 I. In a similar manner as illustrated in  FIG. 6 , a contact pad  20 F and  20 G are formed on the conductive element  14 I. The conductive element  14 J is pressed into an opening  12 J in the laminate  10 J. A contact pad  20 H and  20 I are formed in the conductive element  14 J. A dielectric bonding layer  36  may be deposited between the laminate  10 I and the laminate  10 J. The dielectric bonding layer  36  may be deposited by any suitable means (e.g., spraying, coating, screening, etc.). The dielectric bonding layer  36  may be any suitable adhesive (e.g., a partially cured fiberglass reinforced polymer, adhesiveless thermoplastic, polymide film, etc.). Optionally, an electrically conductive adhesive  38  may be deposited between the contact pads  20 G and  20 H. The electrically conductive adhesive  38  may include any suitable adhesive (e.g., conductive metal filled epoxy, a silver filled thermoset, etc.). 
     FIG. 13  illustrates the assembled stack  32 A with the laminate  10 I bonded to the laminate  10 J and with the contact pads  20 G and  20 H pressed together in electrical contact. 
   While embodiments of the present invention have been described herein for purposes of illustration, many modifications and changes will become apparent to those skilled in the art. For example, the conductive element  14  may be any suitable shape (sphere, cylinder, oval, etc.). Additionally the conductive element  14  may be solid or hollow. The conductive element  14  may deform or the laminate  10  may deform, or both the conductive element  14  and the laminate  10  may deform. Accordingly, the appended claims are intended to encompass all such modifications and changes as fall within the true spirit and scope of this invention.