An Alternative Micro LED Mass Transfer Technology
Self-Assembly
Liangzheng Ji (Fudan University)
Guo Qi Zhang (TU Delft - Electronic Components, Technology and Materials)
Jing Zhang (Heraeus Materials Technology )
Pan Liu (Fudan University)
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Abstract
Micro LED display technology has been spotlighted as the most promising technology compared to LCD and OLED. Its excellent advantages include higher brightness, self-illumination, higher resolution, lower power consumption, faster response, higher integration, higher stability, thinner thickness, longer life, etc. In terms of the unique benefits, it is attracting increasing attention from industries. With the commercialization of Micro LED technology, the following hurdles are identified: wafer manufacturing, full color, bonding, and mass transfer. Among them, mass transfer is so far considered as the most severe bottleneck. Several mass transfer technologies have emerged, including fine picking and placing, roll printing, laser transferring, and fluid self-assembly, which aim to solve the mass transfer problems. However, the aforementioned first 3 types of technologies still rely on the pick-and-place process, which is limited when the Micro LED die dimension shrinks to smaller scales due to processability and equipment precision. Fluidity self-assembly, on the other hand, will not be constrained by the Micro LED size and machine accuracy in the mass transfer process, which received increasing attention from researchers. In the self-assembly of component level, gravitational attraction, magnetic /electromagnetic fields, and capillary force are considered the mainstream force to facilitate the assembly process. Therefore, the component self-assembly becomes a prospective substitute for the Micro LED mass transfer solution, which overcomes the problems of the trade-off between throughput and the placement accuracy of the pick-and-place technology.