First-principles study on elastic properties of Cu, (Cu 1-x Ni x ) 3 Sn and interfacial mechanical properties of (Cu 1-x Ni x ) 3 Sn/Cu in the lead-free solder joint

chemistry Medicinal and pharmaceutical chemistry Nano- and molecular-scale electronics Nano-biomaterials and bioscience Nanomagnetics Nanomaterials, thin films and nanointerfaces Nanomedicine Nanometrology and nanomechanics Nano-optics Nanopatterning, self-assembly and nanofabrication Nanostructures for energy and sensing applications Natural products chemistry Organo main group chemistry Other nanotechnology (unclassified) Other organic chemistry (unclassified) Photochemistry and photovoltaics Physical organic chemistry Supramolecular chemistry In this study, the elastic properties of Cu and (CuxNi1-x)3Sn are calculated to reveal the effects of Ni alloying on the interfacial mechanical properties of (CuxNi1-x)3Sn/Cu in lead-free solder joints. The results reveal that, within the thermodynamically stable domain of (CuxNi1-x)3Sn, the increase of Ni content can enhance the interfacial mechanical properties of (CuxNi1-x)3Sn/Cu, and increase the reliability of the lead-free solder joints. The enhancement mechanism can be attributed the improvements of orientated Young's modulus and ductility of (CuxNi1-x)3Sn achieved by Ni alloying. But higher Ni content beyond the thermodynamically stable domain of (CuxNi1-x)3Sn will deteriorate the interfacial mechanical properties by mechanical mechanism or thermodynamical mechanism, and decrease the reliability of the lead-free solder joints. The results presented in this study will not only unveil the effects of Ni alloying on the interfacial properties of lead-free solder joints, but also will provide a guidance for the high-performed lead-free solder design by alloying strategies to meet the requirements for electronic device miniaturization and harsh environmental applications.

Lead-free Solder; Elastic Modulus; Ductility; work of adhesion; Interfacial Toughness; When a peer-reviewed version of this preprint is available, this information will be updated in the information box above. If no peer-reviewed version is available, please cite this preprint using the following information: Hua, G. Beilstein Arch. 2026, 20261. doi:10.3762/bxiv.2026.1.v1 Citation data can be downloaded as file using the "Download" button or used for copy/paste from the text window below. Citation data in RIS format can be imported by all major citation management software, including EndNote, ProCite, RefWorks, and Zotero. © 2026 Hua; licensee Beilstein-Institut. This is an open access work licensed under the terms of the Beilstein-Institut Open Access License Agreement (https://www.beilstein-archives.org/xiv/terms), which is identical to the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0). The reuse of material under this license requires that the author(s), source and license are credited. Third-party material in this work could be subject to other licenses (typically indicated in the credit line), and in this case, users are required to obtain permission from the license holder to reuse the material.