Patent ID: 6641712
Filing Date: 2003-11-04
Classification: C22B,C23F,C25C,H05K,Y02P

Abstract:
A method for selective dissolution of tin and/or lead- or tin-containing alloys from printed circuit boards without substantial dissolution of copper or precious metals and without attack on plastics associated with electronic components mounted to printed circuit boards, the method comprising steps of:(i) providing a solution comprising Ti(IV) and an acid which forms stable and soluble salt of Ti(III), Ti(IV), Sn(II) and Pb(II); (ii) contacting a printed circuit board with the solution under anaerobic conditions for a time sufficient to effect dissolution of substantially all of the Sn and/or Pb- or Sn-containing alloy therefrom, as Sn(II) and/or Pb(II); (iii) subjecting the solution from step (ii) to electrolytic reduction in order to recover substantially all of the Sn(II) and/or Pb(II) species contained therein as Sn and/or Pb; and (iv) oxidizing the solution from step (iii) to regenerate the oxidant metal species and recycling the regenerated solution to step (i) of the process.