Morphology Variations of Primary Cu6Sn5 Intermetallics in Lead-Free Solder Balls

Research output: Contribution to book/Conference proceedings/Anthology/ReportConference contributionContributed

Contributors

Abstract

This study focuses on the morphologies of primary Cu6Sn5 intermetallics in small free standing SnCu (Ø 270 μm) solder balls. Those showed a large variety of different shapes and sizes ranging from facetted hexagonal rods, to partly facetted splitting crystals and parallel growing branches, to dendritic crystals without facets. The results of electron backscatter diffraction (EBSD) measurements confirm [0001] as the major growth direction and the {10I0} planes as facets of the hexagonal rods. The formation of splitting crystals parallel to the {10I0} planes may be caused by a slight deviation of the major growth direction towards <;2II0>. Morphology transition to dendritic structures can be influenced primarily by increasing the Cu content of the alloy and the cooling rate. However, strong variations occur even if the composition and the cooling rate are constant. Differences in undercooling of the Cu6Sn5 phase have been discussed as a possible reason, since a decreasing solidification temperature promotes a faster initial phase growth due to the increasing oversaturation of the melt's Cu content.

Details

Original languageGerman
Title of host publication2018 7th Electronic System-Integration Technology Conference (ESTC)
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Pages1-8
Number of pages8
ISBN (print)978-1-5386-6815-3
Publication statusPublished - 21 Sept 2018
Peer-reviewedNo

Conference

Title7th Electronic System-Integration Technology Conference
Abbreviated titleESTC 2018
Conference number7
Duration18 - 21 September 2018
Website
LocationWestin Bellevue
CityDresden
CountryGermany

External IDs

Scopus 85060007717
ORCID /0000-0001-8576-7611/work/165877192

Keywords

Keywords

  • Crystals, Morphology, Intermetallic, Shape, Cooling, Temperature measurement, Soldering