無電解スズめっきに関する研究

SnCl₂-KOH系無電解スズめっき浴の再生と管理

抄録

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)₆^2-
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)₆^2- 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.