Journal of Materials Research

Articles

Crystal orientation of β-Sn grain in Ni(P)/Sn–0.5Cu/Cu and Ni(P)/Sn–1.8Ag/Cu joints

Sun-Kyoung Seo, Moon Gi Cho and Hyuck Mo Leea1 c1

a1 Department of Materials Science and Engineering, KAIST, Yuseong-gu, Daejeon, 305-701, Republic of Korea

Abstract

Electron backscatter diffraction analysis was used to compare the crystal orientation of β-Sn grains in Ni(P)/Sn–0.5Cu/Cu and Ni(P)/Sn–1.8Ag/Cu joints before and after aging. In Ni(P)/solder/Cu joints, the solder composition (Cu versus Ag) significantly affects β-Sn grain orientation. In Ni(P)/Sn–0.5Cu/Cu, there are two types of small columnar grains grown from Ni(P) and Cu under bump metallurgy with a high-angle grain boundary crossing the joint closer to the Ni side; in contrast, Ni(P)/Sn–1.8Ag/Cu has large grains with low-angle boundaries. During thermal aging at 150 °C for 250 h, the Ni(P)/Sn–0.5Cu/Cu joints undergo a more significant microstructural change than the Ni(P)/Sn–1.8Ag/Cu joint. Additionally, obvious ledges developed along the high-angle grain boundary between the upper and lower areas in the Sn–0.5Cu joint.

(Received January 08 2010)

(Accepted July 15 2010)

Key Words:

  • Soldering;
  • Microstructure;
  • Texture

Correspondence:

c1 Address all correspondence to this author. e-mail: hmlee@kaist.ac.kr

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