Numerical Analysis of the Thermal and Mechanical Performance of Cu Pillar Bumps During Reflow: Effects of Height and Solder Material

• Published in: Journal of electronic materials Vol. 53; no. 3; pp. 1169 - 1182
• Main Authors: Lee, Jing Rou, Chong, Mun Xi, Abdul Aziz, Mohd Sharizal, Khor, Chu Yee, Mohd Salleh, Mohd Arif Anuar, Mohd Arif Zainol, Mohd Remy Rozainy, Ani, F. Che
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2024; Springer Nature B.V
• Subjects: Bismuth; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copper; Deformation; Electronic Packaging and Interconnections 2023; Electronics and Microelectronics; Finite element method; Finite volume method; Fluid-structure interaction; Instrumentation; Materials Science; Mechanical engineering; Mechanical properties; Numerical analysis; Optical and Electronic Materials; Simulation; Software; Soldering; Solders; Solid State Physics; Temperature; Temperature distribution; Thermal simulation; Thermal stress; Tin; Tin base alloys; Topical Collection: Electronic Packaging and Interconnections 2023; soldering material; surface-mount technology; Copper pillar height; infrared-convection reflow oven; fluid–structure interaction
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-023-10782-3

This paper investigates the impact of various copper (Cu) pillar bump heights on temperature distribution, deformation and thermal stress during reflow. The virtual reflow oven environment was simulated using the fluid domain of the oven model. The accuracy of the fluid analysis was verified by comparing the obtained results with experimental data, which was conducted based on the Joint Electron Device Engineering Council (JEDEC) Standard. In addition, a grid independence test was carried out on the fluid mesh to determine the optimal mesh size for the simulations. A thermal fluid–structure interaction (FSI) approach was employed to couple the thermal results from the fluid analysis with the solid assembly. The results of the coupling analysis revealed that Cu pillar bumps with a height of 0.09 mm exhibited the lowest reflow temperature, minimal maximum deformation, and thermal stress, indicating that it is the optimal potential height for forming a good joint. The study also examines the impact of soldering materials, such as tin-bismuth (SnBi) and tin-silver-copper solder alloys (SAC305 and SAC405), on the Cu pillar bump. This study enables a comprehensive analysis of the thermal and mechanical performance of different Cu pillar bump parameters during the reflow process.