Method of forming conductive pattern, wiring substrate, electronic device and electronic equipment

Abstract

A method of forming a conductive pattern having superior conductivity and better adhesion with a substrate is provided, thereby enabling a thick conductive pattern to be formed. The method comprises the steps of preparing a substrate, forming a metallic core containing metallic particles on the substrate by a droplet ejecting method so that the metallic core has a pattern substantially the same as the predetermined conductive pattern, and forming a plating layer so as to cover the surface of the metallic core by carrying out at least one electroless plating to thereby obtain the conductive pattern. A wiring substrate having the conductive pattern formed by the method, an electronic device provided with the wiring substrate and electronic equipment provided with the electronic device are also provided.

1 . A method of forming a predetermined conductive pattern on a substrate, comprising the steps of: 
 preparing a substrate;    forming a metallic core containing metallic particles on the substrate by a droplet ejecting method so that the metallic core has a pattern substantially the same as the predetermined conductive pattern; and    forming a plating layer so as to cover the surface of the metallic core by carrying out at least one electroless plating to thereby obtain the conductive pattern.    
   
   
       2 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein the average thickness of the metallic core is in the range of 1 to 1 to 10 μm.  
   
   
       3 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein the metallic particles are mainly formed of at least one material selected from the group comprising gold, silver, copper, nickel, palladium and an alloy containing at least one of these metals.  
   
   
       4 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein prior to the formation of the plating layer a catalyst is applied onto the surface of the metallic core selectively.  
   
   
       5 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein in the plating layer forming step the electroless plating is carried out two or more times, and prior to each electroless plating after the first electroless plating has been carried out a catalyst is applied selectively onto the surface of the plating layer which has been formed by the preceding electroless plating.  
   
   
       6 . The method for forming a predetermined conductive pattern as claimed in  claim 4 , wherein the catalyst is mainly constituted from a material selected from the group comprising palladium, platinum, rhodium, iridium and tin and alloys containing at least one of these metals.  
   
   
       7 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein in the plating layer forming step the electroless plating is carried out two or more times, and in each of the electroless platings the same electroless plating solution is used.  
   
   
       8 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein in the plating layer forming step the electroless plating is carried out two or more times, and in each of the electroless platings a different electroless plating solution is used.  
   
   
       9 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein the plating layer is mainly formed of a material selected from the group comprising nickel, silver, gold and copper.  
   
   
       10 . The method for forming a predetermined conductive pattern as claimed in  claim 5 , wherein the thickness of the plating layer formed by the fist electroless plating is in the range of 100 to 1000 nm.  
   
   
       11 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein the thickness of the second or subsequent plating layer is in the range of 1 to 10 μm.  
   
   
       12 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , further comprising prior to the metallic core forming step a step for forming a primary layer for the metallic core onto the substrate.  
   
   
       13 . The method for forming a predetermined conductive pattern as claimed in  claim 12 , wherein the primary layer is provided for enhancing the adhesiveness between the metallic core and the substrate.  
   
   
       14 . The method for forming a predetermined conductive pattern as claimed in  claim 12 , wherein the primary layer is formed into an electrical insulating layer.  
   
   
       15 . The method for forming a predetermined conductive pattern as claimed in  claim 1 , wherein the substrate is formed into a non-metallic substrate.  
   
   
       16 . A wiring substrate, comprising: 
 a substrate; and    a conductive pattern formed on the substrate using the conductive pattern forming method defined in  claim 1 .    
   
   
       17 . A wiring substrate, comprising: 
 a substrate; and    a conductive pattern including a metallic core containing metallic particles and formed so as to have a predetermined pattern and at least one plating layer provided so as to cover the surface of the metallic core.    
   
   
       18 . An electronic device provided with the wiring substrate defined in claimed  16 .  
   
   
       19 . Electronic equipment provided with the electronic device defined in  claim 18.