Metal stripping additive, composition containing the same, and method for stripping metal by using the composition

Abstract

The present invention provides a metal stripping additive, composition containing the same, and method for stripping metal by using the composition. The metal stripping additive comprises a phosphate, a carbonate, and a component selected from at least one of citric acid or a derivative thereof, oxalate or a derivative thereof, malate or a derivative thereof. The metal stripping additive is used with nitric acid as the metal stripping composition of the present invention. The present method has advantages of being capable of stripping various metals, low corrosion, low toxicity, and being applicable under ambient temperature.

What is claimed is: 
     
         1 . A metal stripping additive, comprising:
 10 to 40 wt % of phosphate;   3 to 15 wt % of carbonate; and   5 to 15 wt % of a component selected from at least one of citric acid or a derivative thereof, oxalate or a derivative thereof, or malate or a derivative thereof.   
     
     
         2 . The metal stripping additive according to  claim 1 , further comprising 5 to 30 wt % of a component selected from at least one of sodium hypochlorite or a derivative thereof, or pyridinesulfonic acid or a derivative thereof. 
     
     
         3 . The metal stripping additive according to  claim 1 , wherein said carbonate is sodium bicarbonate, potassium bicarbonate, sodium carbonate, or a combination thereof. 
     
     
         4 . The metal stripping additive according to  claim 1 , wherein said phosphate is monobasic potassium phosphate, dipotassium hydrogen phosphate, or a combination thereof. 
     
     
         5 . The metal stripping additive according to  claim 1 , wherein said citric acid or a derivative thereof is citric acid monohydrate, trisodium citrate monohydrate, or a combination thereof. 
     
     
         6 . The metal stripping additive according to  claim 1 , further comprising a component selected from at least one of boric acid, sulfate, metal chloride, nitrate, or metal hydroxide. 
     
     
         7 . The metal stripping additive according to  claim 6 , wherein said sulfate is sodium sulfate, ammonium sulfate, potassium sulfate, or a combination thereof. 
     
     
         8 . The metal stripping additive according to  claim 6 , wherein said metal chloride is sodium chloride, ammonium chloride, potassium chloride, or a combination thereof. 
     
     
         9 . The metal stripping additive according to  claim 6 , wherein said nitrate is ammonium nitrate, potassium nitrate, sodium nitrate, or a combination thereof. 
     
     
         10 . The metal stripping additive according to  claim 6 , wherein said metal hydroxide is sodium hydroxide, potassium hydroxide, or a combination thereof. 
     
     
         11 . The metal stripping additive according to  claim 1 , having a pH value of 6.5 to 8.0. 
     
     
         12 . The metal stripping additive according to  claim 1 , wherein said metal stripping additive does not have cyanide, lead, cadmium, mercury, chromium(VI), or a combination thereof. 
     
     
         13 . The metal stripping additive according to  claim 1 , wherein said metal is gold, copper, nickel, tin, palladium, or a combination thereof. 
     
     
         14 . The metal stripping additive according to  claim 1 , having no harm to an object that made of silver, stainless steel, titanium, plastic, or a combination thereof. 
     
     
         15 . A metal stripping composition, comprising:
 40 to 60% (v/v) of nitric acid; and   40 to 60% (v/v) of the metal stripping additive according to  claim 1 .   
     
     
         16 . The metal stripping composition according to  claim 15 , wherein said nitric acid has a concentration of 60 to 70 wt %. 
     
     
         17 . The metal stripping composition according to  claim 15 , wherein said metal stripping composition does not have cyanide, lead, cadmium, mercury, chromium(VI), or a combination thereof. 
     
     
         18 . The metal stripping composition according to  claim 15 , wherein said metal is gold, copper, nickel, tin, palladium, or a combination thereof. 
     
     
         19 . The metal stripping composition according to  claim 15 , having no harm to an object that made of silver, stainless steel, titanium, plastic, or a combination thereof. 
     
     
         20 . A method for stripping metal, comprising the following steps:
 contacting an object to be processed with the metal stripping composition according to  claim 15 .   
     
     
         21 . The method according to  claim 20 , wherein said contacting is accomplished by immersing said object to be processed into said metal stripping composition. 
     
     
         22 . The method according to  claim 20 , wherein said contacting is accomplished at a temperature of 10° C. to 70° C. 
     
     
         23 . The method according to  claim 20 , wherein said contacting is accomplished in a time period of 10 sec to 900 sec. 
     
     
         24 . The method according to  claim 20 , having a stripping rate of 0.01 μm/min to 0.2 μm/min. 
     
     
         25 . The method according to  claim 20 , wherein said metal is gold, copper, nickel, tin, palladium, or a combination thereof. 
     
     
         26 . The method according to  claim 20 , having no harm to an object that made of silver, stainless steel, titanium, plastic, or a combination thereof. 
     
     
         27 . The method according to  claim 20 , wherein said object to be processed is an electronic element. 
     
     
         28 . The method according to  claim 27 , wherein said electronic element is a central processing unit, a printed circuit board, a memory, a filp chip, a mobile phone, a combination thereof.