Electrolytic gold plating method of printed circuit board

Abstract

Disclosed is an electrolytic gold plating method of a PCB, which includes (A) forming an electrolytic copper-plated layer, corresponding to a predetermined copper plating resist pattern, on a substrate, (B) forming an electrolytic gold-plated layer, corresponding to a predetermined gold plating resist pattern, on the substrate using an outer layer of the substrate as a first incoming line for electrolytic gold plating use, and (C) removing a portion of the outer layer of the substrate, on which the electrolytic copper-plated layer is not coated.

1 . An electrolytic gold plating method of a printed circuit board, comprising: 
 (A) forming an electrolytic copper-plated layer, corresponding to a predetermined copper plating resist pattern, on a substrate;    (B) forming an electrolytic gold-plated layer, corresponding to a predetermined gold plating resist pattern, on the substrate using an outer layer of the substrate as a first incoming line for electrolytic gold plating use; and    (C) removing a portion of the outer layer of the substrate, on which the electrolytic copper-plated layer is not coated.    
   
   
       2 . The electrolytic gold plating method as set forth in  claim 1 , further comprising: 
 (D) forming a via hole through the substrate; and    (E) forming an electroless copper-plated layer on the outer layer of the substrate and on a wall of the via hole, prior to the step of (A), the electroless copper-plated layer being used as the first incoming line in the step of (B).    
   
   
       3 . The electrolytic gold plating method as set forth in  claim 2 , wherein the step of (A) comprises: 
 (A-1) coating a copper plating resist on the electroless copper-plated layer of the substrate, and exposing and developing the copper plating resist to form a predetermined copper plating resist pattern on the electroless copper-plated layer;    (A-2) conducting an electrolytic copper plating process, using the outer layer and electroless copper-plated layer of the substrate as a second incoming line for electrolytic copper plating use, to form an electrolytic copper-plated layer, corresponding to the copper plating resist pattern, on the electroless copper-plated layer of the substrate; and    (A-3) removing the copper plating resist.    
   
   
       4 . The electrolytic gold plating method as set forth in  claim 2 , further comprising: 
 (D) processing the outer layer of the substrate to be thin, prior to the step of (A).    
   
   
       5 . The electrolytic gold plating method as set forth in  claim 3 , wherein the copper plating resist includes a photosensitive material.  
   
   
       6 . The electrolytic gold plating method as set forth in  claim 2 , wherein the step of (B) comprises: 
 (B-1) coating a gold plating resist on the electroless copper-plated layer of the substrate, and exposing and developing the gold plating resist to form a predetermined gold plating resist pattern on the electroless copper-plated layer;    (B-2) conducting an electrolytic gold plating process, using the outer layer and electroless copper-plated layer of the substrate as the first incoming line, to form an electrolytic gold-plated layer, corresponding to the gold plating resist pattern, on the electroless copper-plated layer of the substrate; and    (B-3) removing the gold plating resist.    
   
   
       7 . The electrolytic gold plating method as set forth in  claim 6 , further comprising (B-4) conducting an electrolytic nickel plating process, using the electroless copper-plated layer as a third incoming line for electrolytic nickel plating use, to form an electrolytic nickel-plated layer, corresponding to the gold plating resist pattern, on the electroless copper-plated layer of the substrate after the step of (B-1).  
   
   
       8 . The electrolytic gold plating method as set forth in  claim 6 , wherein the gold plating resist includes a photosensitive material.  
   
   
       9 . The electrolytic gold plating method as set forth in  claim 2 , wherein the substrate is dipped in an etching solution capable of etching copper, but not gold, to remove a portion of the electroless copper-plated layer and the outer layer of the substrate, which is not coated with the electrolytic copper-plated layer, in the step of (C), the outer layer of the substrate being in contact with the electroless copper-plated layer.  
   
   
       10 . The electrolytic gold plating method as set forth in  claim 2 , wherein the step of (C) comprises: 
 (C-1) coating an etching resist on the electroless copper-plated layer of the substrate, and exposing and developing the etching resist to form a predetermined etching resist pattern, which is not coated with the electrolytic copper-plated layer, on the electroless copper-plated layer of the substrate;    (C-2) etching a portion of the electroless copper-plated layer and outer layer of the substrate, which is not coated with the etching resist pattern, the outer layer being in contact with the electroless copper-plated layer; and    (C-3) removing the etching resist.    
   
   
       11 . The electrolytic gold plating method as set forth in  claim 10 , wherein the etching resist includes a photosensitive material.  
   
   
       12 . The electrolytic gold plating method as set forth in  claim 10 , wherein the substrate is dipped in an etching solution to remove a portion of the electroless copper-plated layer and the outer layer of the substrate, which is not coated with the electrolytic copper-plated layer, in the step of (C-2), the outer layer of the substrate being in contact with the electroless copper-plated layer.  
   
   
       13 . The electrolytic gold plating method as set forth in  claim 10 , wherein a portion of the electroless copper-plated layer and the outer layer of the substrate, which is not coated with the electrolytic copper-plated layer, is etched through a plasma etching process in the step of (C-2), the outer layer of the substrate being in contact with the electroless copper-plated layer.  
   
   
       14 . The electrolytic gold plating method as set forth in  claim 2 , further comprising (D) coating a solder resist on a patterned substrate to form a predetermined solder resist pattern on the patterned substrate after the step of (C).