Simulation Study on Thermal Mechanical Properties of 3×3 Micro-LED Array in Bonding Process after Mass Transfer

Micro-LED is regarded as the next generation of self-luminous emerging display technology due to its superior optoelectronic performance and wide range of applications. After mass transfer, Micro-LEDs can be interconnected with substrates through hot-press bonding, a process that significantly impacts the reliability of Micro-LED devices. In this study, the thermodynamic behavior of a 3×3 Micro-LED array was simulated using COMSOL software and the finite element method. The effects of different pressure, temperature and bump radius on the stress and deformation of the bump after bonding were simulated. Stress concentration is observed at the interface between the bump and the Micro-LED chip electrode, particularly at the corners of the array. The analysis shows that as bonding temperature increases, Von Mises stress and displacement first rise, then decrease, and finally increase again, reaching a minimum at 200°C. Both parameters also increase with higher bonding pressure. For bump radius, the Von Mises stress and displacement initially decrease and then increase, with a minimum at 4 µm. The bonding temperature has a negligible effect on the displacement direction of the bumps, and the Von Mises stress and displacement on the upper surface are consistently greater than those on the lower surface.