Apparatus and method for treating used electroless plating solutions

Abstract

A method and apparatus for treating an electroless plating solution is provided. The apparatus includes a reaction vessel, a cathode and an anode disposed in the interior of the reaction vessel and in electrical communication with a power source, a drain disposed in the reaction vessel, and a nozzle in fluid communication with the drain, disposed in the reaction vessel such that the nozzle and the drain are separated by the cathode and the anode. The method includes disposing an electroless plating solution in the reaction vessel, recirculating the plating solution through the reaction vessel by draining the plating solution from the reaction vessel and subsequently re-injecting the plating solution into the reaction vessel through the nozzle. A current is driven through the anode and cathode to oxidize reducing agents in the liquid and plate out the metal as the elemental metal.

1 . A method for treating an electroless plating solution, the method comprising: 
 providing a reaction vessel containing an anode, a cathode, a drain and a nozzle, wherein the nozzle is in fluid communication with the drain;    disposing the electroless plating solution in the reaction vessel such that the anode and the cathode are at least partially immersed in the plating solution;    recirculating the plating solution through the reaction vessel by draining the plating solution from the reaction vessel through the drain and subsequently re-injecting the plating solution into the reaction vessel through the nozzle;    placing the anode and cathode in electrical communication with a power source and driving an electrical current through the anode and the cathode to produce a treated plating liquid.    
     
     
         2 . The method of  claim 1 , including oxidizing plating solution reducing agents at the anode and reducing plating solution metal salt at the cathode.  
     
     
         3 . The method of  claim 1 , additionally comprising sparging the reaction vessel with an inert gas to create a sparge gas.  
     
     
         4 . The method of  claim 3 , wherein said sparging the reaction vessel includes removing residual liquid from the sparge gas and venting the sparge gas to a hydrogen gas scrubber.  
     
     
         5 . The method of  claim 3 , wherein the inert gas consists essentially of nitrogen gas.  
     
     
         6 . The method of  claim 1 , wherein the anode comprises steel and the cathode comprises brass.  
     
     
         7 . The method of  claim 1 , wherein the plating solution is maintained at a temperature of about 50 degrees C. or less.  
     
     
         8 . The method of  claim 1 , wherein the electrical current is between about 1 and about 10 amperes.  
     
     
         9 . The method of  claim 1 , additionally comprising exposing the treated plating liquid to an ion exchange resin.  
     
     
         10 . The method of  claim 1 , wherein the reaction vessel additionally comprises a metal compound-restrictive filter disposed such that only substantially metal particle-free liquid passes through the drain.  
     
     
         11 . The method of  claim 1 , including monitoring the progress of the treating.  
     
     
         12 . An apparatus for treating an electroless plating liquid, the apparatus comprising: 
 a reaction vessel;    a cathode and an anode in electrical communication with a power source,    wherein the cathode and anode are disposed in the interior of the reaction vessel;    a drain disposed in the reaction vessel;    a nozzle in fluid communication with the drain, disposed in the reaction vessel such that the nozzle and the drain are separated by the cathode and the anode.    
     
     
         13 . The apparatus of  claim 12 , additionally comprising a gas sparger in communication with an inert gas source.  
     
     
         14 . The apparatus of  claim 13 , wherein the reaction vessel is vented and in communication with a hydrogen gas scrubber.  
     
     
         15 . The apparatus of  claim 12 , wherein the reaction vessel additionally comprises a heat exchanger.  
     
     
         16 . The apparatus of  claim 12 , wherein the anode comprises steel and the cathode comprises brass.  
     
     
         17 . The apparatus of  claim 12 , additionally comprising a metal compound-restrictive filter disposed such that only liquid substantially free of metal particles passes through the filter and through the drain.