Abstract
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
Original language | English |
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Pages (from-to) | 1834-1837 |
Number of pages | 4 |
Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
Volume | 46A |
Issue number | 5 |
DOIs | |
State | Published - May 2015 |
Keywords
- BUMP METALLIZATION; SOLDER; RELIABILITY