Unusual Morphological Evolution of the Cu Pillar/Solder Micro-joints During High-Temperature Annealing

Hsi-Kuei Cheng, Yu-Jie Lin, Hou-Chien Chang, Kuo-Chio Liu, Ying-Lang Wang, Tzeng-Feng Liu, Chih Ming Chen

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

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 languageEnglish
Pages (from-to)1834-1837
Number of pages4
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume46A
Issue number5
DOIs
StatePublished - May 2015

Keywords

  • BUMP METALLIZATION; SOLDER; RELIABILITY

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