Study of interfacial reactions between Sn(Cu) solders and Ni-Co alloy Layers

K. C. Huang, F. S. Shieu, T. S. Huang, C. T. Lu, C. W. Chen, H. W. Tseng, S. L. Cheng, C. Y. Liu

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

The interfacial reactions between electroplated Ni-yCo alloy layers and Sn(Cu) solders at 250°C are studied. For pure Co layers, CoSn 3 is the only interfacial compound phase formed at the Sn(Cu)/Co interfaces regardless of the Cu concentration. Also, the addition of Cu to Sn(Cu) solders has no obvious influence on the CoSn 3 compound growth at the Sn(Cu)/Co interfaces. For Ni-63Co layers, (Co,Ni,Cu)Sn 3 is the only interfacial compound phase formed at the Sn(Cu)/Ni-63Co interfaces. Unlike in the pure Co layer cases, the Cu additives in the Sn(Cu) solders clearly suppress the growth rate of the interfacial (Co,Ni,Cu)Sn 3 compound layer. For Ni-20Co layers, the interfacial compound formation at the Sn(Cu)/Ni-20Co interfaces depends on the Cu content in the Sn(Cu) solders and the reflow time. In the case of high Cu content in the Sn(Cu) solders (Sn-0.7Cu and Sn-1.2Cu), an additional needle-like interfacial (Ni x,Co y,Cu 1-x-y ) 3Sn 4 phase forms above the continuous (Ni x,Cu y,Co 1-x-y )Sn 2 compound layer. The Ni content in the Ni-yCo layer can indeed reduce the interfacial compound formation at the Sn(Cu)/Ni-yCo interfaces. With pure Sn solders, the thickness of the compound layer monotonically decreases with the Ni content in the Ni-yCo layer. As for reactions with the Sn(Cu) solders, as the compound thickness decreases, the Ni content in the Ni-yCo layers increases.

Original languageEnglish
Pages (from-to)2403-2411
Number of pages9
JournalJournal of Electronic Materials
Volume39
Issue number11
DOIs
StatePublished - Nov 2010

Keywords

  • Interfacial reactions
  • Sn(Cu) solder

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