The Pd distribution and Cu flow pattern of the Pd-plated Cu wire bond and their effect on the nanoindentation

Yu Wei Lin, Ren You Wang, Wun Bin Ke, I. Sheng Wang, Ying Ta Chiu, Kuo Chang Lu, Kwang Lung Lin, Yi Shao Lai

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The Pd plating on the 20. μm Cu wire dissolves in the free air ball (FAB) and the Cu ball bond during the wire bonding process without forming intermetallic compounds. The limiting supply of Pd and the short bonding process, 15. ms of thermosonic bonding, result in uneven distribution of Pd in the as produced Cu ball bond. Also, the Pd-rich phase may accompany small voids formed within the FAB and the wire bond, and following the direction of semi-solid Cu flow. The Pd distribution, as evidenced by the focused ion beam (FIB) and wavelength dispersive X-ray spectroscopy (WDS) mapping, reveals the whirlpool flow pattern of Cu within the FAB and the ball bond. Pd distributes within the copper ball through convective transport by the copper flow. Additionally, hardness measurements by nanoindentation testing show that the Cu ball bond is harder in the regions where Pd exists.

Original languageEnglish
Pages (from-to)152-157
Number of pages6
JournalMaterials Science and Engineering A
Volume543
DOIs
Publication statusPublished - 2012 May 1

All Science Journal Classification (ASJC) codes

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

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