Method for producing a printed circuit board

Abstract

Methods for producing a printed circuit board and printed circuit boards are disclosed, including a method in which a slot is formed in a substrate, the substrate having at least three layers with the slot extending through at least two of the layers. The slot has a length and a width with the length being greater than the width. The sidewall of the substrate surrounding the slot is coated with a conductive layer. The conductive layer is separated into at least two segments that are electrically isolated along the side wall of the substrate.

What is claimed is: 
     
         1 . A method for making a printed circuit board, comprising the steps of:
 forming, with a router, a slot in a substrate, the substrate having multiple layers of traces and insulators including an internal trace, the substrate having a first side and a second side and having at least three layers, the slot extending through at least two of the at least three layers from the first side and terminating prior to intersecting the second side of the substrate such that the slot is blind, the slot having a length and a width, with the length being greater than the width, the slot having a bottom and a perimeter sidewall surrounding the slot, wherein at least a portion of the perimeter sidewall is linear along the length of the slot;   applying a laser to the bottom of the slot;   coating the perimeter sidewall of the substrate with a conductive layer; and   separating the conductive layer into at least two conductive segments that are electrically isolated along the perimeter sidewall of the substrate for providing an electrical connection between the internal trace and another internal or external trace.   
     
     
         2 . The method of  claim 1 , wherein the step of separating the conductive layer into at least two segments that are electrically isolated is defined further as creating at least one cross-slot by removing a first portion of the conductive layer and the substrate and a second portion of the conductive layer and the substrate. 
     
     
         3 . The method of  claim 2 , wherein the first portion and the second portion are aligned and located on opposite sides of the slot. 
     
     
         4 . The method of  claim 2 , wherein the first portion and the second portion are spaced apart along the length of the slot. 
     
     
         5 . The method of  claim 1 , wherein the step of separating the conductive layer into the at least two conductive segments that are electrically isolated is defined further as positioning a tool having a diameter less than the slot into the slot so as to avoid contact with the conductive layer as the tool is positioned within the slot, and moving the tool laterally into the conductive layer and the perimeter sidewall to form at least one cross-slot separating the conductive layer into the at least two conductive segments. 
     
     
         6 . The method of  claim 1 , wherein the slot has a floor, and further comprising coating the floor with the conductive layer, and wherein separating the conductive layer is defined further as removing a portion of the conductive layer on the floor of the slot. 
     
     
         7 . The method of  claim 1 , wherein the method further comprises filling the slot with a non-conductive filling material; and forming an electromagnetic shield within the non-conductive filling material between the two conductive segments. 
     
     
         8 . The method of  claim 7 , wherein the slot is a first slot, and wherein forming the electromagnetic shield is defined further as forming a second slot within the non-conductive filling material, and positioning a conductive material within the second slot to form the electromagnetic shield. 
     
     
         9 . The method of  claim 8 , wherein positioning the conductive material within the second slot is defined further as plating a perimeter sidewall forming a boundary of the second slot with the conductive material. 
     
     
         10 . The method of  claim 8 , wherein positioning the conductive material within the second slot is defined further as filling the second slot with the conductive material. 
     
     
         11 . The method of  claim 10 , wherein the conductive material is a conductive paste. 
     
     
         12 . The method of  claim 1 , further comprising one or more additional layers covering the slot in the substrate, such that the slot is in a buried configuration. 
     
     
         13 . The method of  claim 1 , wherein forming the slot with the router in the substrate further comprises forming the slot with a bit that can be moved in at least two different lateral directions within the substrate to remove portions of the conductive layer and/or the substrate. 
     
     
         14 . The method of  claim 1 , further comprising introducing a filling material into the slot. 
     
     
         15 . The method of  claim 1 , wherein the substrate is a flexible thin-film substrate. 
     
     
         16 . The method of  claim 1 , wherein the step of separating the conductive layer into at least two segments that are electrically isolated along the perimeter sidewall of the substrate, is defined further as:
 applying a photoresist to the conductive layer;   exposing predetermined portions of the photoresist to light from a laser using a fiber tip supported and guided by a computerized guiding system; and   etching predetermined portions of the conductive layer between the at least two segments to electrically isolate the at least two segments.   
     
     
         17 . The method of  claim 1 , wherein the step of separating the conductive layer into at least two segments that are electrically isolated along the perimeter sidewall of the substrate, is defined further as:
 applying a photoresist to the conductive layer;   exposing predetermined portions of the photoresist to light from a fiber tip located inside of the slot; and   developing and etching predetermined portions of the conductive layer between the at least two segments to electrically isolate the at least two segments.   
     
     
         18 . The method of  claim 1 , wherein the length of the slot is at least 2.85 times greater than the width of the slot.