Abstract
In two previous papers, a new type of bath was proposed for electroless tin plating to be applied in the disproportionation of Sn(II) ion involving
2Sn(OH)3-→Sn+Sn(OH)62-
Sn(II) Sn(O) Sn(IV)
This results in the accumulation of Sn (IV) ion in the used bath as the product of the plating operation.
This paper reports a study of the used SnCl2-KOH system baths in which Sn (IV) had accumulated.
The following results were obtained.
1. The addition of BaCl2 solution to the used bath caused Ba2+ ion to react selectively with Sn(OH)62- and precipitate as BaSn(OH)6·nH2O.
2. After filtration of the precipitate and replenishment of SnCl2 into the used bath, it was possible to carry out normal electroless tin plating.
3. Even after five or more reclamation cycles, the bath remained stable and compact regular tin deposits were obtained.
