Research on the reliability of Micro LED high-density solder joints under thermal cycling conditions

For the purpose of studying the effect of high-density, small-size solder joints on the thermal fatigue life of display devices, a 3D model of the corresponding device structure is established, using finite element analysis methods, and using Anand constitutive equations and Coffin-Manson life prediction models. The equivalent stress and strain change law of an indium solder joint with a diameter of 10 μm under thermal cycling loading conditions is explored, and the key position of the solder joint damage is inferred based on the simulated strain cloud diagram. In addition, the influence of different bump height, bump contact area and Under-Bump Metallization (UBM) thickness on the thermal fatigue life of solder joints is studied separately. The final simulation results show that the location where the solder joint may be damaged first is at the point on the outer side where the solder joint is connected to the UBM on the edge away from the center point. The height of the bump and the contact area of the bump have a significant effect on its thermal fatigue life. In the actual experiment, we should focus on the impact of this aspect.