No.10（2015）6.Development of boron free nickel electroplating for electronic components

Kaori Urasaki, Shota Takemura, Satoshi Kuwahara, Tadashi Doi

  In general, the plating for electronic components is a duplex plating process consisting of nickel plating as under-coat and gold plating as top-coat. The nickel plating bath called "nickel sulfamate plating bath" is used for under-coat plating but the sulfamate bath contains boric acid. In recent years, boron free nickel plating bath is required in Japan, because boron became subject to the effluent regulation. On the other hand, for decorative plating, boron free nickel plating bath called "citric acid bath" was developed. This bath uses citric acid as an alternative to boric acid. The citric acid bath has already been launched for some plating industries in Japan. Aiming at an expansion of industrial application of the citric acid bath, we proposed to apply the nickel electroplating using the citric acid bath as an under-coat for gold plating of electronic components. Generally the high speed electroplating method (hoop plating) is conducted under higher cathode current density than that of decorative plating. In this study, surface properties and corrosion resistances of gold plating undercoated by the citric acid bath and the sulfamate bath were examined. As a result, it was found that the nickel plating by citric acid bath gave better corrosion resistance for gold plating than that of the sulfamate bath. That might be due to the difference in under-coat nickel surface properties between both.

Keywords
Nickel electroplating, Low environmental road, Boron free, Plating for electronic components

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