Nucleation and growth of Ag3Sn in Sn-Ag and Sn-Ag-Cu solder alloys
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Large Ag3Sn plates in solder joints can affect the reliability of electronics, however, the factors affecting their nucleation and morphology are not well understood. Here, the faceted solidification of Ag3Sn was studied as a function of melt undercooling, revealing transitions from single crystal {001} plates to cyclic twinned plates and then to highly branched structures created by twin mediated branching. Real-time X-ray imaging proved that Ag3Sn cyclic twins come from a common point, indicating they initiate in the process of nucleation or in the very early stages of growth in the undercooled melt. Soldering to copper substrates significantly catalysed Ag3Sn nucleation. This is shown to be due to constitutional supercooling generated by Ag solute rejection into the liquid ahead of the Cu6Sn5 reaction layer, with additional contributions from geometrical catalysis in the grooves between Cu6Sn5 scallops and heterogeneous nucleation of Ag3Sn on Cu6Sn5. The relative ease of Ag3Sn nucleation on the Cu6Sn5 reaction layer is responsible for the large plates often reported in electronic solder joints.
Date Issued
2023-05-01
Date Acceptance
2023-03-05
Citation
Acta Materialia, 2023, 249, pp.1-15
ISSN
1359-6454
Publisher
Elsevier
Start Page
1
End Page
15
Journal / Book Title
Acta Materialia
Volume
249
Copyright Statement
© 2023 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/).
(http://creativecommons.org/licenses/by/4.0/).
License URL
Identifier
https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000955385900001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=a2bf6146997ec60c407a63945d4e92bb
Subjects
BETA-SN
COOLING RATE
DROPLET SOLIDIFICATION
GRAIN-REFINEMENT
HETEROGENEOUS NUCLEATION
IN-SITU
Intermetallic compounds (IMCs)
LEAD-FREE SOLDERS
Materials Science
Materials Science, Multidisciplinary
MECHANICAL-PROPERTIES
Metallurgy & Metallurgical Engineering
PLATE FORMATION
Science & Technology
Soldering
Solidification
Synchrotron radiation
Technology
THERMAL FATIGUE
Undercooling
Publication Status
Published
Article Number
ARTN 118831
Date Publish Online
2023-03-06