Self-assembly of flat micro components by capillary forces and shape recognition

This paper summarizes our recent reports on self-assembly of flat micro components based on two major mechanisms: capillary-driven self-assembly and feature-directed self-assembly. The capillary-driven self-assembly is demonstrated in both a liquid environment and an air environment, and high accuracy self-alignment is achieved due to interfacial energy minimization. Working devices such as Light Emitting Diode (LED) and PZT components are successfully assembled by the capillary-driven self-assembly processes. The feature-directed self-assembly relies on complementary features on micro components and receptor sites, thereby has no constraint on component shapes. Two different feature-directed and uniquely orienting self-assembly processes are demonstrated: one is a semi dry process based on gravity-driven self-alignment, and the other is a completely dry process based on two-stage shape recognition. The feature-directed and uniquely orienting self-assembly processes can be applied to either wafer level packaging of micro devices or part feeding and palletizing for robotic assembly systems.