Precipitation and coarsening of bismuth plates in Sn-Ag-Cu-Bi and Sn-Cu-Ni-Bi solder joints
File(s)Belyakov2019_Article_PrecipitationAndCoarseningOfBi.pdf (4.17 MB)
Published version
Author(s)
Type
Journal Article
Abstract
In recent years there has been increased interest in Bi-containing solders to improve the reliability of electronics and drive down processing temperatures. When the Bi content is more than ~ 2 wt% in Sn–Ag–Cu–Bi and Sn–Cu–Ni–Bi solders, (Bi) phase forms by a non-equilibrium eutectic reaction and also precipitates in the solid state. Here, we study the development of bismuth plates during room temperature storage in a range of Bi-containing solders. It is shown that Bi plates precipitate with one of two (Bi)–βSn orientation relationships (ORs). During coarsening the OR with the better lattice match grows at the expense of the other, leading to a single OR. The plate coarsening kinetics scale with the cube root of holding time and are relatively rapid, with plates exceeding 1 µm in length within 1 day at room temperature. Prolonged room temperature storage of more than 1 year resulted in Bi accumulation in 5–20 µm (Bi) particles at βSn grain boundaries.
Date Issued
2019-01-01
Date Acceptance
2018-10-26
Citation
Journal of Materials Science: Materials in Electronics, 2019, 30 (1), pp.378-390
ISSN
0957-4522
Start Page
378
End Page
390
Journal / Book Title
Journal of Materials Science: Materials in Electronics
Volume
30
Issue
1
Copyright Statement
© The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Grant Number
EP/M002241/1
EP/R018863/1
Subjects
0912 Materials Engineering
Applied Physics
Publication Status
Published
Date Publish Online
2018-10-31