Lightweight circuit board with conductive constraining cores

Abstract

Prepregs, laminates, printed wiring board structures and processes for constructing materials and printed wiring boards that enable the construction of printed wiring boards with improved thermal properties. In one embodiment, the prepregs include substrates impregnated with electrically and thermally conductive resins. In other embodiments, the prepregs have substrate materials that include carbon. In other embodiments, the prepregs include substrates impregnated with thermally conductive resins. In other embodiments, the printed wiring board structures include electrically and thermally conductive laminates that can act as ground and/or power planes.

1 . A printed wiring board including multiple functional layers, comprising:
 a layer containing carbon;   wherein at least the layer containing carbon forms a functional layer of the printed wiring board.   
     
     
         2 . The printed wiring board of  claim 1 , wherein at least the layer containing carbon forms a power plane. 
     
     
         3 . The printed wiring board of  claim 1 , wherein at least the layer containing carbon forms a ground plane. 
     
     
         4 . The printed wiring board of  claim 1 , wherein at least the layer containing carbon forms a split plane. 
     
     
         5 . The printed wiring board of  claim 1 , wherein the layer containing carbon includes woven carbon fibers. 
     
     
         6 . The printed wiring board of  claim 1 , wherein the layer containing carbon includes at least one sheet of unidirectional carbon fibers. 
     
     
         7 . The printed wiring board of  claim 1 , wherein the layer containing carbon has a dielectric constant greater than 6.0 at 1 MHz. 
     
     
         8 . The printed wiring board of  claim 1 , wherein the layer containing carbon includes a carbon substrate impregnated with a resin. 
     
     
         9 . The printed wiring board of  claim 8 , wherein the resin is a thermally conductive resin. 
     
     
         10 . The printed wiring board of  claim 8 , wherein the resin is an electrically and thermally conductive resin. 
     
     
         11 . The printed wiring board of  claim 1 , further comprising holes lined with electrically conductive material extending through the printed wiring board. 
     
     
         12 . The printed wiring board of  claim 1 , wherein at least one of the holes lined with electrically conductive material creates an electrical connection between the functional layer formed by at least the layer containing carbon and another functional layer within the printed wiring board. 
     
     
         13 . The printed wiring board of  claim 1 , further comprising:
 a first prepreg layer positioned above the substrate;   a second prepreg layer positioned below the substrate;   a first layer of electrically conductive material positioned above the first prepreg layer; and   a second layer of electrically conductive material positioned below the second prepreg layer.   
     
     
         14 . The printed wiring board of  claim 13 , wherein the laminate formed by the layer containing carbon, the first and second prepregs and the first and second layers of electrically conductive material has a dielectric constant greater than 6.0 at 1 MHz. 
     
     
         15 . The printed wiring board of  claim 1 , further comprising a second layer containing carbon. 
     
     
         16 . The printed wiring board of  claim 15 , wherein at least the second layer containing carbon acts as a second functional layer of the printed wiring board. 
     
     
         17 . The printed wiring board of  claim 15 , wherein the second layer containing carbon does not form part of a functional layer of the printed wiring board. 
     
     
         18 . A method of constructing a printed wiring board, comprising:
 forming a stack of layers of electrically conductive material and at least one layer containing carbon, where the layers of electrically conductive material and layers of carbon are separated by layers of dielectric material;   forming circuits on the layers of electrically conductive material;   drilling holes through the stack and lining the holes with electrically conductive material, where the holes are drilled in locations that enable the layer containing carbon to form a functional layer within the printed wiring board.   
     
     
         19 . The method of  claim 18 , wherein the holes are drilled in locations so that the layer containing carbon forms a power plane in the printed wiring board. 
     
     
         20 . The method of  claim 18 , wherein the holes are drilled in locations so that the layer containing carbon forms a ground plane in the printed wiring board.