Dendrite growth in single-grain and cyclic-twinned Sn–3Ag–0.5Cu solder joints
File(s)s11661-024-07580-9.pdf (3.43 MB)
Published version
Author(s)
Sun, Sihan
Gourlay, Christopher
Type
Journal Article
Abstract
The microstructure of electronic solder joints is generated by the solidification of a small volume
of bulk undercooled liquid. Here, we study b-Sn dendrite growth in Sn–3Ag–0.5Cu in the
specific geometry and nucleation conditions of ball grid array (BGA) solder joints by combining
electron backscatter diffraction and imaging of microstructures. It is shown that, while h110i is
the preferred dendrite growth direction, out-of-plane branching and growth with h11Wi
directions are important for allowing dendrites to fan out into the spheroidal volume of BGA
joints due to the low symmetry of b-Sn. We find that the crystallographic orientation of b-Sn at
the nucleation point plays a strong role in subsequent dendrite growth. In single-grain joints,
dendrites are often unfavorably oriented for growth, resulting in different types of zig-zag
dendrite growth. In cyclic-twinned joints, it is shown how competitive out-of-plane trunk
growth between three dendrite orientations produces {101} boundaries and the characteristic
beachball microstructure.
of bulk undercooled liquid. Here, we study b-Sn dendrite growth in Sn–3Ag–0.5Cu in the
specific geometry and nucleation conditions of ball grid array (BGA) solder joints by combining
electron backscatter diffraction and imaging of microstructures. It is shown that, while h110i is
the preferred dendrite growth direction, out-of-plane branching and growth with h11Wi
directions are important for allowing dendrites to fan out into the spheroidal volume of BGA
joints due to the low symmetry of b-Sn. We find that the crystallographic orientation of b-Sn at
the nucleation point plays a strong role in subsequent dendrite growth. In single-grain joints,
dendrites are often unfavorably oriented for growth, resulting in different types of zig-zag
dendrite growth. In cyclic-twinned joints, it is shown how competitive out-of-plane trunk
growth between three dendrite orientations produces {101} boundaries and the characteristic
beachball microstructure.
Date Issued
2024-11
Date Acceptance
2024-08-23
Citation
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 2024, 55 (11), pp.4342-4353
ISSN
1073-5623
Publisher
Springer
Start Page
4342
End Page
4353
Journal / Book Title
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume
55
Issue
11
Copyright Statement
© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Identifier
https://link.springer.com/article/10.1007/s11661-024-07580-9
Publication Status
Published
Date Publish Online
2024-09-16