Improvement of Solder Bonding Characteristics Using New Electroless Thin Ni/Au Plating Process

Tomohito KATO^1,3, Hajime TERASHIMA³, Hideto WATANABE³, Mitsuhiro WATANABE², Hideo HONMA², Osamu TAKAI^{1, 2}

1. Graduate School of Engineering, Kanto Gakuin University, 1-50-1, Mutuurahigashi, Kanazawa-ku, Yokohama-shi, Kanagawa, 236-0004, Japan.
2. Material Surface Engineering Research Center, Kanto Gakuin University, Yokohama Kanazawa High-Tech Center, 1-1-1, Fukuura, Kanazawa-Ku, Yokohama-shi, Kanagawa, 236-0004, Japan.
3. Kojima Chemicals Co., LTD., 337-26, Kashiwabara, Sayama-shi, Saitama, 350-1335, Japan.

Abstract: Fine pattern formation (Line Width/Line Space is less than 50µm) using electroless Ni/Au plating, extraneous Ni deposition on the resin area of fine pattern often observed due to the residual Pd catalyst on the patterns. Thinner Ni plating was applied to solve the problem. However, the tendency for local Ni corrosion by the immersion Au plating step increases, and solder connection reliability decreases compared to conventional Ni/Au process. Accordingly, the influence of Pd catalyst deposition conditions on electroless Ni/Au plated film properties was investigated. We propose the direct electroless Ni strike plating on the Cu patterns without the Pd catalyst. Generally, solder bonding strength with the electroless thin Ni/Au plating decreased with increase in Pd catalyst treatment time. On the contrary, solder bonding strength does not influence by the Ni strike plating time. Uniform Ni deposition and good solder bonding strength was accomplished by the application of the electroless Ni strike plating method.

Keywords: Thin electroless Ni/Au plating process, Electroless Ni strike plating, Uniformity of Ni plating film, Intermetallic, Solder ball shear strength.

Pages: 359 – 377 | Full PDF Paper