Precursor substrate, flexible circuit board and process for producing the same

Abstract

The present invention provides a flexible circuit board, comprising at least a multilayer unit disposed on a substrate, wherein the multilayer unit includes: an adhesion enhancing layer formed within the surface of the substrate, a first electrical conducting unit disposed on the adhesion enhancing layer, and a second electrical conducting layer formed on the first electrical conducting layer, wherein the adhesion enhancing layer is Palladium, the first electrical conducting layer is Nickel, and the substrate is composed of polyimide(PI).

What is claimed is: 
     
         1 . A method of manufacturing a flexible circuit board, comprising at least:
 providing a substrate;   adhesively enhancing the surface of the substrate by using an adhesion enhancer, forming an adhesion enhancing layer on the surface of the substrate;   fixing a first electrical conducting layer on the surface of the substrate, forming a precursor substrate;   disposing a photoresist layer on the first electrical conducting layer;   exposing and developing the photoresist according to a circuit configuration diagram to partially remove the photoresist and partially reveal the first electrically conducting layer while leaving behind a remaining photoresist;   coating a metal layer on the revealed portion of the first electrical conducting layer;   removing the remaining photoresist to reveal the first electrical conducting layer under the remaining photoresist; and   etching to remove the revealed first electrical conducting layer and the adhesion enhancing layer under the revealed first electrical conducting layer.   
     
     
         2 . The method of manufacturing a flexible circuit board according to  claim 1 , wherein by adhesively enhancing the surface of the substrate by using an adhesive enhancer, a conductivity treatment is included in the process of forming an adhesion enhancing layer on the surface of the substrate, and the conductivity treatment includes at least processes of roughening and adhesion enhancing on the surface of the substrate. 
     
     
         3 . The method of manufacturing a flexible circuit board according to  claim 2 , wherein the roughening process on the surface of the substrate is chemical roughening, and the chemical roughening includes using chemical agent on the surface of the substrate to roughen by corrosion or ring-opening reactions. 
     
     
         4 . The method of manufacturing a flexible circuit board according to  claim 2 , wherein the roughening process on the surface of the substrate is physical roughening, and the physical roughening includes roughening the surface of the substrate by mechanical means. 
     
     
         5 . The method of manufacturing a flexible circuit board according to  claim 1 , wherein the substrate is made of a material selected from the group consisting of polyimide, polyester, polyethylene terephthalate, polytetrafluoroethylene, liquid crystal polymer, epoxy resin and aramid. 
     
     
         6 . The method of manufacturing a flexible circuit board according to  claim 2 , wherein the substrate is made of a material selected from the group consisting of polyimide, polyester, polyethylene terephthalate, polytetrafluoroethylene, liquid crystal polymer, epoxy resin and aramid. 
     
     
         7 . The method of manufacturing a flexible circuit board according to  claim 1 , wherein the adhesion enhancer is a palladium adhesion enhancer. 
     
     
         8 . The method of manufacturing a flexible circuit board according to  claim 2 , wherein the adhesion enhancer is a palladium adhesion enhancer. 
     
     
         9 . The method of manufacturing a flexible circuit board according to  claim 3 , wherein the adhesion enhancer is a palladium adhesion enhancer. 
     
     
         10 . The method of manufacturing a flexible circuit board according to  claim 5 , wherein the adhesion enhancer is a palladium adhesion enhancer. 
     
     
         11 . A flexible circuit board, comprising:
 at least one multilayer unit disposed on the substrate, including:
 an adhesion enhancing layer disposed on the surface of the substrate; 
 a first electrical conducting layer adhered onto the adhesion enhancing layer; and 
 a second electrical conducting layer positioned on the first electrical conducting layer. 
   
     
     
         12 . The flexible circuit board according to  claim 11 , wherein the substrate is made of a material selected from the group consisting of polyimide, polyester, polyethylene terephthalate, polytetrafluoroethylene, liquid crystal polymer, epoxy resin and aramid. 
     
     
         13 . The flexible circuit board according to  claim 11 , wherein the first electrical conducting layer has a thickness of 50 to 200 nanomenters, and the first electrical conducting layer is an electroless plating layer made of a material selected from the group consisting of copper, nickel, chromium, cobalt, nickel alloy and cobalt alloy. 
     
     
         14 . The flexible circuit board according to  claim 11 , wherein the surface of the substrate includes an upper surface and a lower surface, the substrate has a via hole connecting the upper surface and the lower surface, the multilayer unit is disposed on the upper surface and the lower surface and positioned on the opening of the via hole, the adhesion enhancing layer and the first electrical conducting layer of the multilayer unit extend along the wall of the via hole, and the second electrical conducting layer extend into the via hole thusly electrically connecting the multilayer unit on the upper surface and the multiplayer unit on the lower surface. 
     
     
         15 . The flexible circuit board according to  claim 11 , wherein the adhesion enhancing layer includes a palladium adhesion enhancer. 
     
     
         16 . The flexible circuit board according to  claim 12 , wherein the adhesion enhancing layer includes a palladium adhesion enhancer. 
     
     
         17 . A precursor substrate, comprising:
 a substrate having a surface which is adhesively enhanced and has an adhesion enhancing layer; and   a first electrical conducting layer adhered onto the adhesion enhancing layer, thusly enclosing the surface of the substrate.   
     
     
         18 . The precursor substrate according to  claim 17 , wherein the material of the substrate is polyimide. 
     
     
         19 . The precursor substrate according to  claim 17 , wherein the adhesion enhancing layer includes a palladium adhesion enhancer. 
     
     
         20 . The precursor substrate according to  claim 17 , wherein the first electrical conducting layer has a thickness of  50  to  200  nanomenters, and the first electrical conducting layer is an electroless plating layer made of a material selected from the group consisting of copper, nickel, chromium, cobalt, nickel alloy and cobalt alloy.