Thermomigration of Au in the Microbump

Yifan Yao; Yuanxing Duan; Qinglei Sun; K. N. Tu; Yingxia Liu

doi:10.1109/ICEPT67137.2025.11157215

Thermomigration of Au in the Microbump

Research output: Chapters, Conference Papers, Creative and Literary Works › RGC 32 - Refereed conference paper (with host publication) › peer-review

Abstract

Thermomigration is a noteworthy flux-driven reliability concern, which is directional atomic movement driven by a temperature gradient. In solder-based interconnects, it is enough to cause thermomigration with a temperature gradient of 1000 ℃/cm. In this study, we investigate the thermomigration behavior of Au in the Cu/Ni/solder/Ni/Cu microbump. Surface finish is used when manufacturing microbumps, which introduces Au. With a temperature gradient of 6643 ℃/cm, Au diffuses from the hot side to the cold side and reacts with Sn to form (Au,Ni)Sn₄ intermetallic compound. As a result, (Au,Ni)Sn₄ at the cold end is thicker than that at the hot end. Kinetic analysis is also performed. We do not observe thermomigration of Ni because (Au,Ni)Sn₄ covers the Ni under-bump-metallization, impeding the diffusion of Ni. ©2025 IEEE.

Original language	English
Title of host publication	2025 26th International Conference on Electronic Packaging Technology (ICEPT)
Publisher	IEEE
Number of pages	4
ISBN (Electronic)	978-1-6654-6580-9
ISBN (Print)	978-1-6654-7736-9
DOIs	https://doi.org/10.1109/ICEPT67137.2025.11157215
Publication status	Published - 2025

Funding

This work was supported by Shenzhen Science and Technology Innovation Commission (SGDX20220530111203025), City University of Hong Kong through the start-up grant for newly recruited faculty members (9610566), Guangzhou Nansha District Science and Technology Project (2024ZD010), the University Grants Committee of the Hong Kong Special Administrative Region, China (C1002–22Y), and Research Grants Council Joint Research Scheme (N_CityU141/23). The authors would also like to thank Mr. Yuxuan An for his help in the simulation.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 9 Industry, Innovation, and Infrastructure

Research Keywords

thermomigration
microbump
intermetallic compound

RGC Funding Information

RGC-funded

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10.1109/ICEPT67137.2025.11157215

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@inproceedings{a3947387e72a4421abb0e000c44cc912,

title = "Thermomigration of Au in the Microbump",

abstract = "Thermomigration is a noteworthy flux-driven reliability concern, which is directional atomic movement driven by a temperature gradient. In solder-based interconnects, it is enough to cause thermomigration with a temperature gradient of 1000 ℃/cm. In this study, we investigate the thermomigration behavior of Au in the Cu/Ni/solder/Ni/Cu microbump. Surface finish is used when manufacturing microbumps, which introduces Au. With a temperature gradient of 6643 ℃/cm, Au diffuses from the hot side to the cold side and reacts with Sn to form (Au,Ni)Sn4 intermetallic compound. As a result, (Au,Ni)Sn4 at the cold end is thicker than that at the hot end. Kinetic analysis is also performed. We do not observe thermomigration of Ni because (Au,Ni)Sn4 covers the Ni under-bump-metallization, impeding the diffusion of Ni. {\textcopyright}2025 IEEE.",

keywords = "thermomigration, microbump, intermetallic compound",

author = "Yifan Yao and Yuanxing Duan and Qinglei Sun and Tu, \{K. N.\} and Yingxia Liu",

year = "2025",

doi = "10.1109/ICEPT67137.2025.11157215",

language = "English",

isbn = "978-1-6654-7736-9",

booktitle = "2025 26th International Conference on Electronic Packaging Technology (ICEPT)",

publisher = "IEEE",

address = "United States",

}

TY - GEN

T1 - Thermomigration of Au in the Microbump

AU - Yao, Yifan

AU - Duan, Yuanxing

AU - Sun, Qinglei

AU - Tu, K. N.

AU - Liu, Yingxia

PY - 2025

Y1 - 2025

N2 - Thermomigration is a noteworthy flux-driven reliability concern, which is directional atomic movement driven by a temperature gradient. In solder-based interconnects, it is enough to cause thermomigration with a temperature gradient of 1000 ℃/cm. In this study, we investigate the thermomigration behavior of Au in the Cu/Ni/solder/Ni/Cu microbump. Surface finish is used when manufacturing microbumps, which introduces Au. With a temperature gradient of 6643 ℃/cm, Au diffuses from the hot side to the cold side and reacts with Sn to form (Au,Ni)Sn4 intermetallic compound. As a result, (Au,Ni)Sn4 at the cold end is thicker than that at the hot end. Kinetic analysis is also performed. We do not observe thermomigration of Ni because (Au,Ni)Sn4 covers the Ni under-bump-metallization, impeding the diffusion of Ni. ©2025 IEEE.

AB - Thermomigration is a noteworthy flux-driven reliability concern, which is directional atomic movement driven by a temperature gradient. In solder-based interconnects, it is enough to cause thermomigration with a temperature gradient of 1000 ℃/cm. In this study, we investigate the thermomigration behavior of Au in the Cu/Ni/solder/Ni/Cu microbump. Surface finish is used when manufacturing microbumps, which introduces Au. With a temperature gradient of 6643 ℃/cm, Au diffuses from the hot side to the cold side and reacts with Sn to form (Au,Ni)Sn4 intermetallic compound. As a result, (Au,Ni)Sn4 at the cold end is thicker than that at the hot end. Kinetic analysis is also performed. We do not observe thermomigration of Ni because (Au,Ni)Sn4 covers the Ni under-bump-metallization, impeding the diffusion of Ni. ©2025 IEEE.

KW - thermomigration

KW - microbump

KW - intermetallic compound

UR - https://www.webofscience.com/wos/woscc/full-record/WOS:001592581000166

UR - http://www.scopus.com/inward/record.url?scp=105030953022&partnerID=8YFLogxK

UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-105030953022&origin=recordpage

U2 - 10.1109/ICEPT67137.2025.11157215

DO - 10.1109/ICEPT67137.2025.11157215

M3 - RGC 32 - Refereed conference paper (with host publication)

SN - 978-1-6654-7736-9

BT - 2025 26th International Conference on Electronic Packaging Technology (ICEPT)

PB - IEEE

ER -

Thermomigration of Au in the Microbump

Abstract

Funding

UN SDGs

Research Keywords

RGC Funding Information

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NSFC: Multi-scale Inverse Design and Experimental Verification of High-entropy Solder

YCRG-Sub-pj: Large-scale Lithium Niobate Photonic Integrated Circuits for Neuromorphic Computing

YCRG: Large-scale Lithium Niobate Photonic Integrated Circuits for Neuromorphic Computing

Cite this

Thermomigration of Au in the Microbump

Abstract

Funding

UN SDGs

Research Keywords

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Other Files and Links

Fingerprint

Projects

NSFC: Multi-scale Inverse Design and Experimental Verification of High-entropy Solder

YCRG-Sub-pj: Large-scale Lithium Niobate Photonic Integrated Circuits for Neuromorphic Computing

YCRG: Large-scale Lithium Niobate Photonic Integrated Circuits for Neuromorphic Computing

Cite this