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

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• 作者：Hung-Chun Pan ; Tsung-Eong Hsieh  ; ;   ; ^{tehsieh@mail.nctu.edu.tw}
• 关键词：Electroless Co(W ; P) ; IMC ; Diffusion barrier ; Shear test
• 刊名：Materials Science and Engineering: B
• 出版年：2012
• 出版时间：25 January 2012
• 年：2012
• 卷：177
• 期：1
• 页码：61-68
• 全文大小：1996 K

文摘

Diffusion barrier characteristics, activation energy (E_a) of IMC growth and bonding properties of amorphous and polycrystalline electroless Co(W,P) (termed as ¦Á-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/¦Á-Co(W,P) samples subjected to liquid-state aging at 250 ¡ãC. In contrast, IMCs resided on the P-rich layer in PbSn/¦Á-Co(W,P) samples subjected to solid-state aging at 150 ¡ãC. Thick IMCs neighboring to an amorphous W-rich layer was seen in PbSn/poly-Co(W,P) samples regardless of the aging type. ¦Á-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 E_a's for PbSn/¦Á-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 ¦Á- 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.