Metal substrate double sided circuit board

Abstract

Disclosed is a circuit board and a process for the manufacture thereof providing a circuit board comprising a metal core having parallel first and second major faces and exhibiting high thermal and electrical conductivity. The circuit board includes electrical insulating layers of thermally conductive, dielectric material applied to the first and second major faces of the metal core. Protecting the dielectric layer and copper conductors is a solder mask layer applied to the dielectric layers and forming outward facing major surfaces. A plurality of insulated and grounded vias having electrically conductive interior rings connecting the major surfaces are provided through the board. Conductive sleeves within the vias are either electrically insulated from the metal core by dielectric material or in electrical contact to the metal core for grounding.

What is claimed is: 
     
       1. A circuit board comprises: a metal core having parallel first and second major faces and exhibiting high thermal and electrical conductivity;   dielectric layers of thermally conductive material applied to the first and second major faces of the metal core;   a plurality of insulated and grounded vias through metal core and the dielectric layers;   an electrically conductive sleeve within each insulated and grounded vias, wherein the electrically conductive sleeves in the insulated vias are electrically insulated from the metal core by dielectric material and the electrically conductive sleeves in the grounded vias are in electrical contact to the metal core for grounding; and   electrically conductive leads connected to selected ones of the electrically conductive sleeves and applied to each of the dielectric layers and spaced thereby from the metal core,   
     
     
       2. The circuit board of claim 1, wherein the dielectric layers are aluminum nitride, boron nitride, diamond or ceramic polymer composites. 
     
     
       3. The circuit board of claim 2, wherein the metal core is copper, aluminum or anodized aluminum. 
     
     
       4. The circuit board of claim 3, and further comprising: first and second solder mask layers applied over the conductive leads and dielectric layers and forming outward facing major surfaces of the circuit board; and   electronic components mounted to each major surface of the circuit board.   
     
     
       5. The circuit board of claim 1, wherein the dielectric layers are formed of an epoxy or polyimide matrix filled with 50% to 80% by volume with a thermally conductive dielectric. 
     
     
       6. The circuit board of claim 5, where the thermally conductive dielectric is boron nitride, aluminum nitride, diamond, diamond-like carbon or a combination of two or more of the forgoing materials.