Single or multi-layer printed circuit board with improved edge via design

Abstract

A circuit board includes an electrically conductive sheet having an insulative coating surrounding the conductive sheet, with a surface of the insulative coating around an edge of the conductive sheet having an arcuate or rounded shape. At least one electrical conductor is conformally deposited on at least the rounded insulative coating around the edge of the conductive sheet and defined via photolithographic and metallization techniques. Each electrical conductor on the insulative coating thereon around the edge of the conductive sheet conforms to the arcuate or rounded shape of the insulative coating and, therefore, has an arcuate or rounded shape.

1 . A circuit board comprising: 
 an electrically conductive sheet coated with an insulative coating that forms an insulating top layer covering one surface of the conductive sheet, an insulating bottom layer covering another surface of the conductive sheet and an insulating edge layer covering an edge of the conductive sheet; and    a first electrical conductor on one of the insulating top layer and the insulating bottom layer and on at least part of the insulating edge layer, wherein:    the insulating edge layer and the portion of the first electrical conductor thereon each have an arcuate or rounded shape; and    the portion of the first electrical conductor on the insulating edge layer is electrically isolated from the edge of the conductive sheet by the insulating edge layer.    
   
   
       2 . The circuit board of  claim 1 , wherein: 
 the first electrical conductor is also on the other layer of the circuit board; and    the portions of the first electrical conductor on the top and bottom layers of the circuit board are electrically connected by the portion of the first electrical conductor on the insulating edge layer.    
   
   
       3 . The circuit board of  claim 1 , wherein the combination of the portion of the first electrical conductor and the insulating edge layer it overlays is in a notch defined in the edge of the electrically conductive sheet.  
   
   
       4 . The circuit board of  claim 3 , further including a second electrical conductor on the top and bottom layers of the circuit board that are electrically connected by a portion of the second electrical conductor on the insulating edge layer which is in the notch in electrical isolation from the portion of the first electrical conductor in the notch.  
   
   
       5 . The circuit board of  claim 1 , wherein the insulative coating is initially electrodeposited and thereafter is heated until it flows thereby forming the insulating edge layer having the arcuate or rounded shape.  
   
   
       6 . The circuit board of  claim 1 , further including a copper layer disposed between the electrically conductive sheet and the insulative coating.  
   
   
       7 . A method of forming a circuit board comprising: 
 (a) providing an electrically conductive sheet having top and bottom surfaces and an edge;    (b) conformally coating the top and bottom surfaces and the edge of the electrically conductive sheet with an insulating material;    (c) exposing the conformally coated insulating material to an elevated temperature such that the insulating material at least partially melts and flows around the edge of the electrically conductive sheet whereupon, upon removal of the elevated temperature, the insulating material around the edge of the electrically conductive sheet has an arcuate or rounded shape or outline; and    (d) following step (c), forming a first conductor on the insulating material with at least a portion of the first conductor on the insulating material around the edge of the electrically conductive sheet, whereupon said portion of the first conductor has an arcuate or rounded shape or outline.    
   
   
       8 . The method of  claim 7 , wherein the first conductor is also formed on the insulating material overlaying at least one of the top and bottom surfaces of the electrically conductive sheet.  
   
   
       9 . The method of  claim 7 , wherein said portion of the first conductor and the insulating material it overlays are in a notch formed in a side of the electrically conductive sheet.  
   
   
       10 . The method of  claim 9 , wherein: 
 step (d) includes forming a second conductor on the insulating material with at least a portion of the second conductor overlaying the insulating material in the notch, whereupon said portion of the second conductor has an arcuate or rounded shape or outline; and    said portion of the second conductor in the notch is electrically isolated from said portion of the first conductor in the notch.    
   
   
       11 . The method of  claim 7 , wherein step (b) includes electrodepositing the insulating material.  
   
   
       12 . The method of  claim 7 , wherein said portion of the first conductor electrically connects other portions of said first conductor on the insulating material overlaying the top and bottom surfaces of the electrically conductive sheet.  
   
   
       13 . A circuit board comprising: 
 an electrically conductive sheet including an insulating edge layer covering an edge of the conductive sheet; and    an electrical conductor on the insulating edge layer, wherein:    the insulating edge layer and the electrical conductor have an arcuate or rounded shape or outline.    
   
   
       14 . The circuit board of  claim 13 , further including at least one of: 
 the electrical conductor on an insulating top layer overlaying a top surface of the electrically conductive sheet; and    the electrical conductor on an insulating bottom layer overlaying a bottom surface of the electrically conductive sheet.    
   
   
       15 . The circuit board of  claim 13 , wherein the combination of the electrical conductor and the insulating edge layer it overlays is in a notch in the edge of the conductive sheet.  
   
   
       16 . The circuit board of  claim 15 , further including another electrical conductor on the insulating edge layer in the notch, wherein the electrical conductors on the insulating edge layer in the notch are spaced from each other.  
   
   
       17 . The circuit board of  claim 15 , further including another electrical conductor on the insulating edge layer outside the notch.  
   
   
       18 . A circuit board comprising: 
 an electrically conductive sheet;    an insulative coating surrounding the conductive sheet with a surface of the insulative coating around an edge of the conductive sheet being rounded; and    at least one electrical conductor conformally deposited on at least the rounded insulative coating around the edge of the conductive sheet and defined via photolithographic and metallization techniques such that said electrical conductor on the rounded insulative coating around the edge of the conductive sheet has a rounded surface.    
   
   
       19 . The circuit board of  claim 18 , wherein the edge of the conductive sheet defines a notch therein where at least one electrical conductor formed on at least the rounded insulative coating resides.  
   
   
       20 . The circuit board of  claim 19 , wherein: 
 two electrical conductors reside in the notch; and    the two electrical conductors are electrically isolated from each other in the notch.