Current-induced growth of P-rich phase at electroless nickel/Sn interface

Qiliang Yang, Panju Shang, Jing D. Guo, Zhiquan Liu, Jian Ku Shang

Research output: Contribution to journalArticlepeer-review

Abstract

The role of high current stressing during growth of the P-rich phase at the electroless Ni/Sn interface was examined by transmission electron microscopy. Prior to current stressing, two layers of Ni12P5, columnar Ni12P5 and noncolumnar Ni12P5 were formed after soldering. Upon electric stressing, the two layers of P-rich phase showed opposite growth patterns at the two opposing electrode interfaces. At the cathode, columnar growth of the P-rich phase was greatly enhanced while growth of the noncolumnar layer was inhibited. By contrast, the opposite was found at the anode where the current stressing promoted the noncolumnar growth but suppressed the growth of the columnar layer. Such a strong polarity effect resulted from directional electromigration of the key reaction species, nickel, to and from the interfacial reaction fronts. As a result of the difference in reaction mechanism, overall growth of the P-rich phase was much faster at the cathode during current stressing.

Original languageEnglish (US)
Pages (from-to)2767-2774
Number of pages8
JournalJournal of Materials Research
Volume24
Issue number9
DOIs
StatePublished - Sep 2009

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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