Manufacturing method of circuit board assembly for high frequency signal transmission

Abstract

A manufacturing method of copper foil and circuit board assembly for high frequency transmission are provided. Firstly, a raw copper foil having a predetermined surface is produced by an electrolyzing process. Subsequently, a roughened layer including a plurality of copper particles is formed on the predetermined surface by an arsenic-free electrolytic roughening treatment and an arsenic-free electrolytic surface protection treatment. Thereafter, a surface treatment layer is formed on the roughened layer, and the roughened layer is made of a material which includes at least one kind of non-copper metal elements and the concentration of the non-copper metal elements is smaller than 400 ppm. By controlling the concentration of the non-copper elements, the resistance of the copper foil can be reduced.

What is claimed is: 
     
         1 . A manufacturing method of circuit board assembly for high frequency transmission, comprising:
 providing a copper foil, the copper foil has laminating surface, wherein providing the copper foil includes:
 producing a raw copper foil having a predetermined surface by an electrolyzing process; 
 forming a roughened layer on the predetermined surface of the raw copper foil, wherein the step of forming a roughened layer further includes an arsenic-free electrolytic roughening treatment and an arsenic-free electrolytic surface protection treatment; and 
 forming a surface treatment layer on the roughened layer, wherein the surface treatment layer is made of a material including at least one non-copper metal element, and the concentration of the non-copper metal element is smaller than 400 ppm; and 
   laminating a substrate with the copper foil with the laminating surface thereof facing the substrate.   
     
     
         2 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein a ten point height of irregularities of the laminating surface is 2 to 3 μm; and the copper foil is heated under 200° C. for 2 hours, and has a resistance value of less than 0.16 ohm-gram/m 2 . 
     
     
         3 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein the substrate is a high frequency substrate, and the high frequency substrate is an epoxy resin substrate, a polyphenylene oxide resin substrate, a fluorine-based resin substrate, or a liquid crystal polymer substrate. 
     
     
         4 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein the substrate is made of polyimide, ethylene terephthalate, polycarbonate or polytetrafluoroethylene. 
     
     
         5 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein the step of laminating a substrate with the copper foil further comprises: providing an adhesive layer to bond the copper foil and the substrate to each other. 
     
     
         6 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein the substrate is directly bonded to the copper foil. 
     
     
         7 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , further comprising: etching the copper foil to form a wiring layer. 
     
     
         8 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein the circuit board assembly is a printed circuit board or a flexible printed circuit board. 
     
     
         9 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein the step of forming a surface treatment layer includes: performing a heat-resistant plating treatment to form a zinc alloy heat-resistant layer, wherein the first plating solution composition of the heat-resistant plating treatment includes zinc from 1 to 4 g/L and nickel form 0.3 to 2.0 g/L, and the current density in performing the heat-resistant plating treatment is 0.4 to 2.5 A/dm 2 . 
     
     
         10 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , wherein a temperature of a roughening plating bath of the arsenic-free electrolytic roughening treatment ranges from 20 to 40° C., and the current density is between 15 to 40 A/dm 2 ; and a temperature of a curing plating bath of the arsenic-free electrolytic surface protection treatment ranges from 50 to 70° C., and the current density ranges from 2 to 9 A/dm 2 . 
     
     
         11 . The manufacturing method of circuit board assembly for high frequency transmission according to  claim 1 , the step of producing a raw copper foil further comprising: applying an electric current to an electrolyte, and the electrolyte includes copper ions 50 to 90 g/L, sulfuric acid 50 to 120 g/L and chloride ions with a concentration of less than 1.5 ppm.