無電解めっきによるビスマス皮膜の形成

抄録

Electroless deposition of bismuth has been achieved, probably for the first time, using stannous chloride as a reducing agent. Bismuth films were autocatalytically deposited on aluminum substrate activated with palladium at a rate of 1.84mg·cm^-2·h^-1.
Optimum bath composition were 0.08M, 0.34M, 0.20M, 0.08M and 0.04M for bismuth trichloride, trisodium citrate, NTA, disodium EDTA and stannous chloride, respectively. Rapid film deposition was obtained at pH8.8 and 60°C.
The films were grown to the desired thickness by renewing the plating bath every 30 minutes.
It was observed from X-ray analysis and X-ray fluorescence spectrometry that the crystal structure of deposited film was not affected by the plating conditions, and that it contained no trace of tin.
UV absorption spectra of the plating bath showed that the EDTA formed complex salts with Bi³⁺, Sn²⁺, and Sn⁴⁺, while the citric acid and NTA served as solvents for the insoluble complex salts formed by EDTA with Sn²⁺ and Sn⁴⁺.