Method of forming a flexible circuit board

Abstract

A process of forming a flexible circuit board for ink jetting is provided. The process includes the steps of: providing an insulation tape; forming conductive traces on the insulation tape; and forming a photo-polymer layer filling between the conductive traces, wherein parts of the conductive traces are exposed to form a plurality of contacts. The material of the insulation tape can be polyimide, Teflon, polyamide, polymethylmethacrylate, polycarbonate, polyester, polyamide polyethylene-terephthalate copolymer, or any combination of the above materials. The material of the photo-polymer layer can be solder mask or polyimide.

What is claimed is:  
     
         1 . A method of forming a flexible circuit board for ink jetting, comprising of: 
 providing an insulation tape;    forming conductive traces on the insulation tape; and    after the conductive traces are formed on the insulation tape, forming a photo-polymer layer that fills between the conductive traces, wherein the photo-polymer layer has holes formed therein so that parts of the conductive traces are not covered by the photo-polymer layer to form a plurality of uncovered contacts that are exposed by the holes.    
     
     
         2 . The method according to  claim 1 , wherein the insulation tape comprises a polymer film.  
     
     
         3 . The method according to  claim 2 , wherein a material of the polymer film comprises at least one of polyimide (PI), Teflon, polyamide, polymethyl methacrylate, polycarbonate, polyester, and polyamide polyethylene-terephthalate copolymer.  
     
     
         4 . The method according to  claim 2 , wherein a material of the polymer film is polyimide (PI).  
     
     
         5 . The method according to  claim 1 , wherein the forming the conductive traces comprises of: 
 forming an adhesive layer on the insulation tape;    adhering a conductive layer on the adhesive layer; and    defining the pattern of the conductive layer to form the conductive traces.    
     
     
         6 . The method according to  claim 5 , wherein a material of the conductive layer is copper.  
     
     
         7 . The method according to  claim 5 , wherein a material of the conductive layer is gold.  
     
     
         8 . The method according to  claim 5 , wherein a thickness of the conductive layer is about 10 μm to 50 μm.  
     
     
         9 . The method according to  claim 1 , wherein the photo-polymer layer is formed by coating.  
     
     
         10 . The method according to  claim 1 , wherein the photo-polymer layer is formed by one of screen printing, spray coating, curtain coating and roller coating.  
     
     
         11 . The method according to  claim 1 , wherein the photo-polymer layer is made of solder mask.  
     
     
         12 . The method according to  claim 1 , wherein the photo-polymer layer is made of polyimide.  
     
     
         13 . The method according to  claim 1 , wherein the forming a photo-polymer layer comprises coating, exposing, developing and post-curing.  
     
     
         14 . The method according to  claim 13 , wherein the photo-polymer layer is made of solder mask and the solder mask comprises a main agent and a hardener with a ratio of about 7:3.  
     
     
         15 . The method according  claim 13 , wherein the exposing is performed with an exposure energy of about 280˜420 mJ/cm 2 .  
     
     
         16 . The method according to  claim 13 , wherein the post-curing is performed at a hot air convention oven at about 150 ? for about 50 min.