Interfacial reaction between Cu substrates and Zn-Al base high-temperature Pb-free solders

Yoshikazu Takaku, Lazuardi Felicia, Ikuo Ohnuma, Ryosuke Kainuma, Kiyohito Ishida

Research output: Contribution to journalArticlepeer-review

72 Citations (Scopus)


Chemical reactions between Cu substrates and Zn-Al high-temperature solder alloys, Zn-4Al and Zn-4Al-1Cu (mass%), at temperatures ranging from 420°C to 530°C were experimentally investigated by a scanning electron microscope using backscattered electrons (SEM-BSE) and an electron probe microanalyzer (EPMA). Intermediate phases (IMPs), β(A2) or β(B2), γ(D8 2), and ε(A3) phases formed and grew during the soldering and aging treatments. The consumption rate of the IMP for Cu substrates is described by the square root of t in both the alloys, while the additional Cu in the molten Zn-Al alloy slightly suppresses the consumption of Cu substrates. The growth of IMPs during soldering treatment is controlled by the volume diffusion of constituent elements, and its activation energy increases in the order of Q ε < Q γ < Q β. In view of the aging process, the growth of IMPs is considered to be controlled by the volume diffusion. In particular, the layer thickness of γ rapidly grows over 200°C, although the thickness of the β layer grows very slowly.

Original languageEnglish
Pages (from-to)314-323
Number of pages10
JournalJournal of Electronic Materials
Issue number3
Publication statusPublished - 2008 Mar


  • Cu
  • Intermediate phases (IMP)
  • Reaction
  • Solder

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry


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