Three-Layer Zn/Al/Zn Clad Solder for Die Attachment

Journal of Electronic Materials, Feb 2015, Volume 44, Issue 2, pp 751-760.

T. Yamaguchi ^{(1) (4)} , O. Ikeda ⁽¹⁾ ,Y. Oda ⁽²⁾ ,S. Hata ⁽³⁾, K. Kuroki ⁽³⁾,H. Kuroda⁽³⁾ ,A. Hirose ⁽⁴⁾

 

1. Manufacturing Technology Research Center, Yokohama Research Laboratory, Hitachi, Ltd., 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa-ken, 244-0817, Japan and
2. Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita-shi, Osaka-fu, Japan and
3. Engineering Department, NEOMAX MATERIALS, Co., Ltd., 2-19-1, Minamisuita, Suita-shi, Osaka-fu, 564-0043, Japan and
4. Electric Materials Business Unit, Cable Materials Company, Hitachi Metals, Ltd., 4-10-1 Kawajiri-cho, Hitachi-shi, Ibaraki-ken, 319-1411, Japan.

 

Abstract

Three-layer Zn/Al/Zn clad solders have been developed for high-temperature die attachment. The clad structure is used to improve the wettability and bondability of Zn-Al eutectic solder by preventing oxidation of the Al. The materials were produced by clad-rolling Zn and Al strips. TEM observations revealed that the Zn/Al clad interface was metallurgically bonded and that the Al oxide was almost entirely removed. The melting behavior of Zn/Al/Zn clad solder was examined. Eutectic melting began at the Zn/Al clad interface at 382°C, and all of the material melted within approximately 10 s. Unlike conventional Zn-Al solders, Zn/Al/Zn clad solders were successfully bonded without flux. The shear strength of a Zn/Al/Zn clad solder joint was three times that of a Pb-based solder joint. The bondability of Zn/Al/Zn clad solder was superior because the Al oxide films, which prevent bonding between chip and substrate, were fragmented by clad-rolling, and the outer Zn layers prevented Al oxidation during the bonding process.

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