Studies on size and lubricant effects for fluidic self-assembly of microparts on patterned substrate using capillary effect

Conventional pick-and-place technology platform in handling microscale component assembly processes has technical limitations in terms of capacity, efficiency, and accuracy. The fluidic self-assembly (FSA) approach employs a lubricant fluid carrying micropart flows over a target wafer patterned with binding sites, which results in part-substrate attachment. This technique transports microparts from one location to another with orientation control and parallel sorting. The present study demonstrates a FSA approach for fast, economic, and precise handling of microscale parts with square (few are in rectangular) shapes. The microparts fabricated from silicon-oxide wafers and ranging in size from 350×350×170 μm³ to 1000×1000×440 μm³ aligned and filled to designated sites in the substrate under water. The effects of micropart sizes and lubricants on the FSA processes are compared. This study provides a fundamental analysis for achieving and optimizing the self-alignment. The polymer or solder adhesion force of the square-patterned micropart immobilized at the larger binding sites were estimated to be 117 ± 15 fiN and 510 ± 50 /JLN, respectively, which results in higher assembly yield of up to 100% for these samples. Copyright © 2008 by ASME.