C.uyemura Co., Ltd.

Naoshi Nishimura

Katsuhisa Tanabe

Tsuyoshi Maeda

Tatsushi Someya

Tetsuya Sasamura

Eriko Furuya

Yohei Kaneko

The present invention provides an electroless gold plating bath having excellent plating bath stability without containing a cyanide compound under long term plating bath heating time. An electroless gold plating bath of the present invention solving above problems includes: a water-soluble gold salt; a reducing agent; and a phosphine compound represented by a following formula (1) wherein R, R, and Rrepresent identically or differently either a phenyl group, or an alkyl group having 1 to 5 carbons, and at least one of the phenyl group or the alkyl group is substituted by a sulfonate group or its salt, a cyano group, or a carboxy group or its salt.

Electroless gold plating bath

A film formation method is provided with a catalyst film formation step for forming a catalyst film on the surface of a substrate by displacement reduction plating, an intermediate film formation step for forming a palladium plating film on the catalyst film, and a surface film formation step for forming a gold plating film on the palladium plating film.

Film formation method

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Osaka, Japan

Naoshi Nishimura