Method of forming conductive tracks

Abstract

A patterned electrical conductor is obtained by exposing, to a desired conductive pattern, a photosensitive element comprising a support and a photosensitive material coated thereon which is sensitive to the wavelength of exposing radiation and capable of providing a latent image upon exposure, developing the exposed element to form a developed metal (e.g. silver) image being capable of conducting on having a voltage applied across it, and electroplating the metal image with a second metal (e.g. silver) to form a conductive pattern having improved conductivity, without the need for an intermediate physical development or electroless plating step.

1 . A process for preparing a patterned electrical conductor comprising the steps of 
 providing a photosensitive element comprising a support substrate and a photosensitive material coated onto said support, said photosensitive material being capable of providing a latent image on exposure to sensitising radiation;    exposing said photosensitive element to sensitising radiation according to a desired conductive track pattern to form a latent image on said photosensitive element;    developing said latent image to form a developed image formed by a first metal corresponding to the desired conductive track pattern, said image formed by said first metal being capable of conducting when a voltage is applied across it; and    electroplating said developed metal image with a plating of a second metal to improve the conductivity of said developed metal image to form a conductive track according to the desired pattern.    
   
   
       2 . The process of  claim 1 , wherein said photosensitive material comprises a silver halide emulsion in gelatin and said first metal is silver.  
   
   
       3 . The process of  claim 1 , wherein said electroplating step comprises applying a voltage across said developed metal image in the presence of a solution of a salt of said second metal.  
   
   
       4 . The process of  claim 3 , wherein said second metal is selected from silver, gold, zinc, lead, copper or nickel.  
   
   
       5 . The process of  claim 4 , wherein said second metal is silver.  
   
   
       6 . The process of  claim 3 , wherein said electroplating step comprises applying a voltage across said developed metal image in the presence of a solution of a silver thiosulfate complex.  
   
   
       7 . The process of  claim 6 , wherein said silver thiosulfate solution is present in a concentration of from 0.01 to 0.1 molar.  
   
   
       8 . A patterned electrically conductive element comprising a conductive track pattern on a support substrate, said element being obtainable by the process of 
 providing a photosensitive element comprising said support substrate and a photosensitive material coated onto said support, said photosensitive material being capable of providing a latent image on exposure to sensitising radiation;    exposing said photosensitive element to sensitising radiation according to a desired conductive track pattern to form a latent image on said photosensitive element;    developing said latent image to form a developed image formed by a first metal corresponding to the desired conductive track pattern, said image formed by said first metal being capable of conducting when a voltage is applied across it; and    electroplating said developed metal image with a plating of a second metal to improve the conductivity of said developed metal image to form a conductive track according to the desired pattern.    
   
   
       9 . The element of  claim 8 , wherein said photosensitive material comprises a silver halide emulsion in gelatin and said first metal is silver.  
   
   
       10 . The element of  claim 9 , wherein said photosensitive material comprises a silver halide emulsion in gelatin, wherein said silver halide is present in an amount of at least 1 g/m 2 .  
   
   
       11 . The element of  claim 8 , wherein said second metal is selected from silver, gold, zinc, lead, copper or nickel.  
   
   
       12 . The element of  claim 11 , wherein said second metal is silver.