Method for surface treating a substrate

Abstract

A method for surface treating a substrate includes following steps. Firstly, a substrate including a metallic surface capable of being electroplated with a metal coating is provided. Secondly, a first metal coating is electroplated onto the metallic surface of the substrate. Thirdly, an oxidized metal film is formed to cover the first metal coating. The first metal coating of substrate is blasted using quartz sand. The oxidized metal film is removed from the first metal coating. The second metal coating is electroplated onto the first metal coating.

1 . A method for surface treating a substrate, comprising the steps of:
 providing a substrate including a metallic surface capable of being electroplated with a metal coating;   electroplating a first metal coating onto the metallic surface of the substrate;   passivating the first metal coating by immersing the substrate into an oxidizing agent to forming an oxidized metal film covering the first metal coating;   sand blasting the first metal coating of substrate;   activating the first metal coating by removing the oxidized metal film from the first metal coating; and   electroplating a second metal coating onto the first metal coating.   
   
   
       2 . The method as claimed in  claim 1 , wherein the substrate is made of plastic, the substrate being metalized by wet chemical deposition. 
   
   
       3 . The method as claimed in  claim 2 , wherein the metallization of the substrate comprises steps of forming a noble metal coating on the substrate and plating a copper layer onto the noble metal coating in a copper electrolyte containing copper salt and sulfuric acid. 
   
   
       4 . The method as claimed in  claim 2 , wherein the substrate is made of plastic selected from a group consisting of acrylonitrile butadiene styrene, poly methyl methacrylate, and polycarbonate. 
   
   
       5 . The method as claimed in  claim 1 , wherein the substrate is made of metal selected from a group consisting of steel, aluminum, titanium, magnesium, and alloys thereof. 
   
   
       6 . The method as claimed in  claim 1 , wherein the first metal coating is made of copper. 
   
   
       7 . The method as claimed in  claim 1 , wherein the thickness of the first metal coating is in a range from about 10 to about 50 microns. 
   
   
       8 . The method as claimed in  claim 1 , wherein the oxidizing agent includes one of chromic acid and chromate salt. 
   
   
       9 . The method as claimed in  claim 1 , wherein the step of sand blasting the first metal coating is carried out using a mixture of quartz sand and water in an air sand blower to strike the first metal coating, to put a plurality of dispersed and distributed dents in the first metal coating. 
   
   
       10 . The method as claimed in  claim 1 , further comprising a step of repeatedly passivating the first metal coating by immersing the substrate into the oxidizing agent after the sand blasting. 
   
   
       11 . The method as claimed in  claim 9 , further comprising a step of immersing the substrate into hydrofluoric acid to remove residual quartz sand particles from the first metal coating. 
   
   
       12 . The method as claimed in  claim 1 , wherein the second metal coating is made of copper and has a thickness less than that of the first metal coating. 
   
   
       13 . The method as claimed in  claim 1 , wherein the thickness of the second metal coating is in a range from about 2 to about 8 microns. 
   
   
       14 . The method as claimed in  claim 1 , wherein the second metal coating is coated with a decorative coating made of chrome, which has a thickness less than that of the second metal coating. 
   
   
       15 . The method as claimed in  claim 14 , wherein the decorative coating is in a range from about 0.1 to about 2 microns. 
   
   
       16 . A method for surface treating a substrate, comprising the steps of:
 providing a substrate including a metallic surface capable of being electroplated with a metal coating;   electroplating a first metal coating onto the metallic surface of the substrate;   forming an oxidized metal film covering the first metal coating;   sand blasting the first metal coating of substrate;   removing the oxidized metal film from the first metal coating; and   electroplating a second metal coating onto the first metal coating.   
   
   
       17 . The method as claimed in  claim 16 , wherein the first metal coating is made of copper and has a thickness in a range from about 10 to about 50 microns. 
   
   
       18 . The method as claimed in  claim 16 , wherein the second metal coating is made of copper and has a thickness less than that of the first metal coating. 
   
   
       19 . The method as claimed in  claim 18 , wherein the thickness of the second metal coating is in a range from about 2 to about 8 microns. 
   
   
       20 . The method as claimed in  claim 16 , wherein the second metal coating is coated with a decorative coating made of chrome, which has a thickness in a range from about 0.1 to about 2 microns less than that of the second metal coating.