Study on Microstructure Formation and Numerical Simulation of Cu-Sn Alloy in Ultrasonic-Assisted Laser Soldering Process

Xinlei Wei; Guoqing Cai; Shaoyang Zhu; Guoqing Mei

doi:10.62051/ijmsts.v4n1.03

Authors

Xinlei Wei
Guoqing Cai
Shaoyang Zhu
Guoqing Mei

DOI:

https://doi.org/10.62051/ijmsts.v4n1.03

Keywords:

Ultrasonic-assisted laser soldering, Cu-Sn alloy, Molten pool flow, Solder joint reliability

Abstract

To reveal the microstructure formation mechanism of Cu-Sn alloy and the synergistic effect law of composite energy fields in the ultrasonic-assisted laser soldering process, this study employed a combination of experimental and numerical simulation methods to systematically investigate the effects of laser power (5-20W) and ultrasonic frequency (0-40kHz) on the temperature field, flow field, growth of interfacial intermetallic compounds (IMC), and reliability of solder joints. The experiment utilized a semiconductor laser system and an ultrasonic auxiliary device, and combined with COMSOL multiphysics simulation to construct a laser-ultrasonic composite energy field model, focusing on analyzing molten pool convection, temperature distribution, creep strain, and failure cycle characteristics. The results show that laser power dominates heat input and determines the energy accumulation state of the molten pool; ultrasonic frequency regulates molten pool flow through acoustic streaming effect, with around 30kHz achieving optimal momentum transfer, significantly improving temperature uniformity and refining the IMC layer; the synergy of high power (15-20W) and ultrasound (30-40kHz) can enhance the wettability and spreadability of solder joints, but excessively high ultrasonic frequency (40kHz) easily causes solder splashing. Accelerated life test simulations indicate that the interfacial region experiences creep strain concentration due to thermal mismatch, which is the weak link of fatigue failure, and ultrasonic assistance can extend the service life of solder joints by reducing the energy dissipation rate. This study clarifies the matching mechanism of laser-ultrasonic parameters, providing a theoretical basis for optimizing high-reliability soldering processes in electronic packaging.

References

[1] Lee J Y, Ju J E, Lee C, et al. Novel fabrication techniques for ultra-thin silicon based flexible electronics [J]. International Journal of Extreme Manufacturing, 2024, 6(4): 042005.

[2] Lau J H. State of the art of lead-free solder joint reliability [J]. Journal of Electronic Packaging, 2021, 143(2): 020803.

[3] Cao B, Su T, Yu S, et al. Active learning accelerates the discovery of high strength and high ductility lead-free solder alloys [J]. Materials & Design, 2024, 241: 112921.

[4] Lin J, Lu J, Xu J, et al. Welding quality analysis and prediction based on deep learning [C]//2021 4th World Conference on Mechanical Engineering and Intelligent Manufacturing (WCMEIM). IEEE, 2021: 173-177.

[5] Zhang C, Fan Z, Dai Y, et al. Path Planning of Laser Soldering System Based on Intelligent Algorithm [J]. Sensors, 2022, 22(21): 8120.

[6] Nishikawa H, Iwata N. Formation and growth of intermetallic compound layers at the interface during laser soldering using Sn–Ag Cu solder on a Cu Pad [J]. Journal of Materials Processing Technology, 2015, 215: 6-11.

[7] Kunwar A, An L, Liu J, Shang S, et al. A data-driven framework to predict the morphology of interfacial Cu6Sn5 IMC in SAC/Cu system during laser soldering. J Mater Sci Technol 2020; 50:115.

[8] Bachok Z, Abas MA, Nazarudin MZH, Zahiri SA, et al. Effect of different solder volumes on the laser soldering process: numerical and experimental investigation. J Electron Packag 2022;144.

[9] Kago K, Suetsugu K, Hibino S, et al. Novel ultrasonic soldering technique for lead-free solders [J]. Materials transactions, 2004, 45(3): 703-709.

[10] Leng X, Yang W, Zhang J, et al. High-performance joining technology for aluminium matrix composites using ultrasonic-assisted brazing [J]. Materials Science and Technology, 2018, 34(6): 660-663.