“…Copper pillar bump is widely used in 3D integrated packaging because of their smaller packaging size, excellent electrical and mechanical properties [5][6][7][8]. Currently, the most advanced threedimensional integration technologies, such as HBM [9,10], CoWoS [11,12], Foveros [13,14], etc., use the diameter of copper pillar bumps of about of 20 μm, while in the field of Micro LED, the size of micro-interconnection has reached 10μm or even smaller [15][16][17][18]. This size will continue to shrink in the future.…”