Immersion method

Abstract

A composition and method for inhibiting corrosion is disclosed. Metals and metal alloys are treated with compositions which contain inorganic and organic acids that prevent oxide formation on the metals and metal alloys.

1 . A composition consisting essentially of one or more phosphoric acids or salts thereof in amounts to inhibit oxide formation on metals and metal alloys.  
     
     
         2 . The composition of  claim 1 , wherein the one or more phosphoric acids comprise inorganic phosphoric acids, or organic phosphoric acids.  
     
     
         3 . The composition of  claim 2 , wherein the organic phosphoric acids comprise alkylphosphoric acids, hydroxyalkyldiphosphoric acids, hydroxyalkylenephosphoric acids, hexaalkylenediamino-tetra(alkylene-phosphoric) acids, aminotris(alkylene-phosphoric) acids, or phosphorocarboxylic acids.  
     
     
         4 . A composition consisting of one or more inorganic phosphoric acids or salts thereof, one or more organic phosphoric acids or salts thereof, and water.  
     
     
         5 . A method comprising contacting a metal or metal alloy with a composition comprising one or more phosphoric acids or salts thereof to inhibit oxidation of the metal or metal alloy.  
     
     
         6 . A method comprising: 
 a) depositing one or more metals or metal alloys on a substrate;    b) contacting the one or more metals or metal alloys with a composition comprising one or more phosphoric acids or salts thereof; and    c) reflowing the one or more metals or metal alloys.    
     
     
         7 . The method of  claim 6 , wherein the one or more metals or metal alloys are deposited on the substrate electrolytically.  
     
     
         8 . The method of  claim 6 , wherein the metal is tin, or the metal alloy is a tin alloy.  
     
     
         9 . The method of  claim 6 , wherein the substrate is a printed wiring board, lead frame or connector.