Electroless Deposition of Tin Using Contact with Zinc Powder in the Bath

• Published in: Hyōmen gijutsu Vol. 65; no. 9; pp. 453 - 457
• Main Authors: UCHIDA, Ei, TANAKA, Kaoru, KAWABATA, Ai, NABESHIMA, Shota, TSURUOKA, Takaaki, AKAMATSU, Kennsuke, NAWAFUNE, Hidemi
• Format: Journal Article
• Language: Japanese
• Published: The Surface Finishing Society of Japan 01.09.2014
• Subjects: Boards; Contact; Contact Immersion Process; Copper; Deposition; Electroless deposition; Electroless Tin Deposition; Flexible Printed Circuit; Joining; Mixed Potential Theory; Printed circuits; Zinc
• ISSN: 0915-1869; 1884-3409
• DOI: 10.4139/sfj.65.453

Electroless deposition of tin film is an important process, particularly for joining in flexible printed circuit board (FPC) and chip-on-film (COF) tapes. Electroless deposition of tin from the tin (Ⅱ)-citrate bath was investigated using contact with zinc powder in the bath. Tin was deposited electrolessly onto a copper substrate by contact with zinc powder in the tin (Ⅱ)-citrate bath. The process, which is environmentally friendly, provides a high tin deposition rate of approximately 8 μmh−1. That rate is much higher than that of the autocatalytic deposition process using TiCl3 as a reducing agent. Furthermore, no copper substrate dissolution was observed. Results of local polarization curve measurements indicate that the mixed potential theory is applicable to this reaction.