Behavior of Sn-3.0Ag-0.5Cu solder/Cu fluxless soldering via Sn steaming under formic acid atmosphere

Siliang He; Yu-An Shen; Bifu Xiong; Fupeng Huo; Jiahui Li; Jinguo Ge; Zhiliang Pan; Wangyun Li; Chuan Hu; Hiroshi Nishikawa

Journal of Materials Research and Technology (Nov 2022)

Behavior of Sn-3.0Ag-0.5Cu solder/Cu fluxless soldering via Sn steaming under formic acid atmosphere

Siliang He,
Yu-An Shen,
Bifu Xiong,
Fupeng Huo,
Jiahui Li,
Jinguo Ge,
Zhiliang Pan,
Wangyun Li,
Chuan Hu,
Hiroshi Nishikawa

Affiliations

Siliang He: Institute of Semiconductors, Guangdong Academy of Sciences, Guangzhou, Guangdong 510650, China; Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology, School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China; Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 565-0047, Japan; Corresponding author.
Yu-An Shen: Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan
Bifu Xiong: Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology, School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China
Fupeng Huo: Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 565-0047, Japan
Jiahui Li: Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 565-0047, Japan
Jinguo Ge: Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology, School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China
Zhiliang Pan: Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology, School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China
Wangyun Li: Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology, School of Mechanical and Electrical Engineering, Guilin University of Electronic Technology, Guilin, Guangxi 541004, China
Chuan Hu: Institute of Semiconductors, Guangdong Academy of Sciences, Guangzhou, Guangdong 510650, China
Hiroshi Nishikawa: Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 565-0047, Japan

Journal volume & issue: Vol. 21
pp. 2352 – 2361

Abstract

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Formic acid (FA) atmosphere is promising to achieve chemical reduction at the oxidized surfaces of the solder and matrix material during soldering, replacing chemical flux being challenging as the continuous decrease in the pitch of solder bump in a three-dimensional integrated circuit. Although a previous study observed the effect of Sn steaming on the wettability of the solder during FA soldering, it has not been understood yet by adequate studies. This study demonstrates the fluxless soldering behavior of Sn-3.0Ag-0.5Cu (SAC) solder/Cu under FA atmosphere. Resembling vulcanian eruption Sn steaming occurred with a solid-state Sn and promoted Sn–Cu intermetallic compound (IMC) formations obviously at temperature (210 ° C) lower than the melting temperature of Sn (231 ° C). As indicated by in-situ observations, the IMC formations led to the final spreading area of solder under FA soldering was larger than that under the soldering with rosin mildly activated (RMA) flux. The wettability of SAC solder under FA atmosphere could be improved with continuous heating.

Published in Journal of Materials Research and Technology

ISSN: 2238-7854 (Print); 2214-0697 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Technology: Mining engineering. Metallurgy
Website: https://www.journals.elsevier.com/journal-of-materials-research-and-technology/

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