Diffusion barrier characteristics and shear fracture behaviors of eutectic PbSn solder/electroless Co(W,P) samples

Hung Chun Pan, Tsung-Eong Hsien*

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Diffusion barrier characteristics, activation energy (Ea) of IMC growth and bonding properties of amorphous and polycrystalline electroless Co(W,P) (termed as α-Co(W,P) and poly-Co(W,P)) to eutectic PbSn solder are presented. Intermetallic compound (IMC) spallation and an nano-crystalline P-rich layer were observed in PbSn/α-Co(W,P) samples subjected to liquid-state aging at 250 °C. In contrast, IMCs resided on the P-rich layer in PbSn/α-Co(W,P) samples subjected to solid-state aging at 150 °C. Thick IMCs neighboring to an amorphous W-rich layer was seen in PbSn/poly-Co(W,P) samples regardless of the aging type. α-Co(W,P) was found to be a sacrificial- plus stuffed-type barrier while poly-Co(W,P) is mainly a sacrificial-type barrier. The values of Ea's for PbSn/α-Co(W,P) and PbSn/poly-Co(W,P) systems were 338.6 and 167.5 kJ/mol, respectively. Shear test revealed the ductile mode dominates the failure in both α- and poly-Co(W,P) samples. Analytical results indicated the high P content in electroless layer might enhance the barrier capability but degrade the bonding strength.

Original languageEnglish
Pages (from-to)61-68
Number of pages8
JournalMaterials Science and Engineering B: Solid-State Materials for Advanced Technology
Volume177
Issue number1
DOIs
StatePublished - 25 Jan 2012

Keywords

  • Diffusion barrier
  • Electroless Co(W,P)
  • IMC
  • Shear test

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