Tin alloy electroplating system

Abstract

Disclosed are systems and methods of plating a tin alloy in an efficient, economical, and environmentally friendly manner. The system for plating a tin alloy contains an electrochemical cell containing an anode, the cathode, and an electroplating bath. The electroplating bath contains water, an acid, at least one nitrogen-containing heterocyclic complexing agent, an ionic alloy metal, and ionic tin. The methods involve applying a current to the electroplating bath whereby a tin alloy forms on the cathode.

1 . A system for plating a tin alloy on a cathode, comprising: 
 an electrochemical cell comprising an anode, the cathode, and an electroplating bath comprising water, an acid, at least one nitrogen-containing heterocyclic complexing agent, an ionic alloy metal, and ionic tin.    
     
     
         2 . The system of  claim 1 , wherein the nitrogen-containing heterocyclic complexing agent comprises at least one selected from the group consisting of substituted or unsubstituted imidazoles, substituted or unsubstituted pyrazoles, substituted or unsubstituted pyrazines, substituted or unsubstituted pyridines, substituted or unsubstituted indoles, and substituted or unsubstituted quinolines.  
     
     
         3 . The system of  claim 1 , wherein the electroplating bath comprises from about 1 g/l to about 300 g/l of at least one substituted or unsubstituted compound represented by Formula III:  
       
         
           
           
               
               
           
         
       
     
     
         4 . The system of  claim 1 , wherein the anode comprises tin.  
     
     
         5 . The system of  claim 1 , wherein the ionic alloy metal comprises at least one metal ion selected from the group of bismuth, copper, silver, zinc, and indium.  
     
     
         6 . The system of  claim 1 , with the proviso that the tin alloy does not comprise substantial amounts of lead.  
     
     
         7 . A system for plating a tin alloy, comprising: 
 an electrochemical cell comprising an anolyte compartment and a catholyte compartment separated by a selective membrane;    the anolyte compartment comprising an anode and anolyte comprising water, an acid, and ionic tin; and    the catholyte compartment comprising a cathode and catholyte comprising water, acid, an ionic alloy metal, and ionic tin,    wherein at least one of the anolyte compartment and the catholyte compartment comprises a nitrogen-containing heterocyclic complexing agent.    
     
     
         8 . The system of  claim 7 , wherein the nitrogen-containing heterocyclic complexing agent comprises at least one selected from the group consisting of substituted or unsubstituted imidazoles, substituted or unsubstituted pyrazoles, substituted or unsubstituted pyrazines, substituted or unsubstituted pyridines, substituted or unsubstituted indoles, and substituted or unsubstituted quinolines.  
     
     
         9 . The system of  claim 7 , wherein the electroplating bath comprises from about 1 g/l to about 300 g/l of at least one substituted or unsubstituted compound represented by Formula III:  
       
         
           
           
               
               
           
         
       
     
     
         10 . The system of  claim 7 , wherein the acid comprises at least one selected from the group consisting of sulfuric acid, trifluoroacetic acid, phosphoric acid, polyphosphoric acid, fluoboric acid, hydrochloric acid, acetic acid, alkane sulfonic acids, and alkanol sulfonic acids.  
     
     
         11 . The system of  claim 7  further comprising a conduit to permit one way flow of anolyte to the catholyte compartment and the catholyte compartment comprises the nitrogen-containing heterocyclic complexing agent.  
     
     
         12 . The system of  claim 11 , wherein the conduit comprises one selected from the group consisting of tubing, piping, an overflow trough, and an aperture in the anolyte compartment.  
     
     
         13 . The system of  claim 7 , with the proviso that the tin alloy does not comprise substantial amounts of lead.  
     
     
         14 . The system of  claim 7 , wherein the anode comprises tin.  
     
     
         15 . The system of  claim 7 , wherein the ionic alloy metal comprises at least one metal ion selected from the group of bismuth, copper, silver, zinc, and indium, and the tin alloy comprises at least about 1% by weight tin and about 99% by weight or less of at least one selected from the group consisting of bismuth, copper, silver, zinc, and indium.  
     
     
         16 . The system of  claim 7 , wherein the tin alloy comprises a high tin alloy comprising at least about 70% by weight tin and about 30% by weight or less of at least one selected from the group consisting of bismuth, copper, silver, zinc, and indium.  
     
     
         17 . A method of electroplating a lead free tin alloy, comprising: 
 providing an electroplating bath comprising an anolyte compartment and a catholyte compartment separated by a selective membrane; the anolyte compartment comprising an anode and anolyte comprising water, an acid, and ionic tin; the catholyte compartment comprising a cathode and catholyte comprising water, acid, at least one ionic alloy metal, and ionic tin, wherein at least one of the anolyte compartment and the catholyte compartment comprises a nitrogen-containing heterocyclic complexing agent;    applying a current to the electroplating bath whereby a lead free tin alloy forms on the cathode.    
     
     
         18 . The method of  claim 17 , wherein the nitrogen-containing heterocyclic complexing agent comprises at least one selected from the group consisting of substituted or unsubstituted imidazoles, substituted or unsubstituted pyrazoles, substituted or unsubstituted pyrazines, substituted or unsubstituted pyridines, substituted or unsubstituted indoles, and substituted or unsubstituted quinolines.  
     
     
         19 . The method of  claim 17 , wherein at least one of the anolyte compartment and the catholyte compartment comprises from about 1 g/l to about 300 g/l of the nitrogen-containing heterocyclic complexing agent.  
     
     
         20 . The method of  claim 17 , wherein the selective membrane prevents the ionic alloy metal of the catholyte from entering the anolyte compartment.  
     
     
         21 . The method of  claim 17 , wherein the anolyte and catholyte each independently have a pH of the of about 3 or less and a current density of about 1 ASF or more and about 1,000 ASF or less is applied to the electroplating bath.  
     
     
         22 . The method of  claim 17 , wherein the electroplating bath has a conduit to permit one way flow of anolyte to the catholyte compartment.  
     
     
         23 . The method of  claim 22 , wherein the conduit comprises one selected from the group consisting of tubing, piping, an overflow trough, and an aperture in the anolyte compartment.  
     
     
         24 . The method of  claim 17 , wherein the anode comprises tin and the ionic alloy metal comprises at least one metal ion selected from the group of bismuth, copper, silver, zinc, and indium.  
     
     
         25 . The method of  claim 17 , wherein the selective membrane comprises an ionic selective membrane or a size selective membrane.