Anti-Overturning Mechanism and Control Strategy In High-Speed Die Peeling-off Process

With the development of LED die manufacturing technology, the LED die sorting performance is required to reach more than 50KUPH. Considering that the die size has developed to 50μm-100μm, and the substrate membrane surface deformation (such as relaxation and creep) is unpredictable, many secondary adjustments are necessary to ensure that the positioning accuracy reaches ±5μm, which is bound to reduce the performance. To solve the dilemma between positioning accuracy and high-speed performance, eccentric peeling is an inevitable choice. How to realize die peeling under eccentric condition has become an urgent problem to be solved. To disclose how eccentric peeling works, the mechanical model is established, and the stress of die in the overturning process is analyzed in detail. The control method of coupling force applied in the process of high-speed peeling is then proposed, and the engineering design criterion of eccentric allowable is induced. According to this eccentric design specification, the die positioning can be safely peeled off even if there is a deviation. After that, the overturning process is simulated by finite element method. Combined with the analysis of deformation and stress, the rationality of eccentricity and nozzle flexibility is verified effective to meets the needs of restraining turnover and safety of stress intensity. The analysis and measurement results show that by reasonably selecting the coupling structure and adjusting the coupling force, the chip overturning risk can be effectively restrained.