Method for manufacturing printed circuit boards

Abstract

A method for manufacturing a PCB is related. The method includes providing a substrate with two opposite conductive layers and defining a through hole passing through the two conductive layers; forming a first electrically conductive metal layer on an inner surface of the substrate in the through hole using an electro-less plating process; forming a second electrically conductive metal layer on the first electrically conductive metal layer using an electro-plating process till the through hole being filled.

1 . A method for manufacturing a PCB, the method comprising:
 providing a substrate including a base and two conductive layers formed on opposite surfaces of the base, the substrate defining a through hole passing through the two conductive layers;   forming a first electrically conductive metal layer on an inner surface of the substrate in the through hole using an electro-less plating process;   forming a second electrically conductive metal layer on the first electrically conductive metal layer using an electro-plating process filling the through hole.   
     
     
         2 . The method as claimed in  claim 1 , further comprising applying a protecting layer onto outer surfaces of the substrate while exposing the through hole before forming the first electrically conductive metal layer. 
     
     
         3 . The method as claimed in  claim 1 , wherein the first electrically conductive metal layer includes a first portion formed on the outer surfaces of the substrate and a second portion formed on the inner surface, the method further comprising applying a protecting layer onto the first portion of the first electrically conductive metal layer while exposing the second portion thereof before forming the second electrically conductive metal layer. 
     
     
         4 . The method as claimed in  claim 2 , wherein the protecting layer is a dry photoresist film, liquid photoresist layer or binder layer. 
     
     
         5 . The method as claimed in  claim 3 , wherein the protecting layer is a dry photoresist film, liquid photoresist layer or binder layer. 
     
     
         6 . The method as claimed in  claim 3 , further comprising removing the protecting layer and the first portion of the first electrically conductive metal layer. 
     
     
         7 . The method as claimed in  claim 1 , further comprising smoothening opposite ends of the second electrically conductive metal layer, the opposite ends thereof protruding from the two opposite conductive layers. 
     
     
         8 . A method for manufacturing a PCB, comprising:
 providing a substrate, the substrate including a base and two conductive layers formed on opposite surfaces of the base and defining a blind hole passing through one of the two conductive layer and the base;   forming a first electrically conductive metal layer on an inner surface of the substrate in the blind hole using an electro-less plating process;   forming a second electrically conductive metal layer on the first electrically conductive metal layer using an electro-plating process till the through hole being filled.   
     
     
         9 . The method as claimed in  claim 8 , further comprising applying a protecting layer onto outer surfaces of the substrate while exposing the blind hole before forming the first electrically conductive metal layer. 
     
     
         10 . The method as claimed in  claim 8 , wherein the first electrically conductive metal layer includes a first portion formed on an outer surfaces of the substrate and a second portion formed on the inner surface, the method further comprising applying a protecting layer onto the first portion of the first electrically conductive metal layer while exposing the second portion thereof before forming the second electrically conductive metal layer. 
     
     
         11 . The method as claimed in  claim 9 , wherein the protecting layer is a dry photoresist film, liquid photoresist layer or binder layer. 
     
     
         12 . The method as claimed in  claim 10 , wherein the protecting layer is a dry photoresist film, liquid photoresist layer or binder layer. 
     
     
         13 . The method as claimed in  claim 10 , further comprising removing the protecting layer and the first portion of the first metal layer. 
     
     
         14 . The method as claimed in  claim 8 , further comprising smoothening opposite ends of the second electrically conductive metal layer, the opposite ends thereof protruding from the two opposite conductive layers.