Browsing by Author "Chang, Hou-Chien"

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Unusual Morphological Evolution of the Cu Pillar/Solder Micro-joints During High-Temperature Annealing
(2015-05-01)
Cheng, Hsi-Kuei
;
Lin, Yu-Jie
;
Chang, Hou-Chien
;
Liu, Kuo-Chio
;
Wang, Ying-Lang
The morphological evolution of Cu pillars capped with Sn-1.8 wt pct Ag solder during high-temperature annealing was investigated. Two intermetallic compounds (Cu6Sn5 + Cu3Sn) formed at the Cu/solder interface which changed the pillar\'s morphology. Surface diffusion enhanced the growth of Cu6Sn5 + Cu3Sn around the pillar brim and transformed the pillar top from a plane into a truncated cone. Bulk diffusion dominated after long-term annealing and the pillar top became hemispherical shaped. A mechanism was proposed to explain the unusual morphological evolution. (C) The Minerals, Metals & Materials Society and ASM International 2015