Fluidic Self-Assembly of Semiconductor Devices: A Promising New Method of Mass-Producing Flexible Circuitry

Small electronic chips have been successfully assembled in a rapid fashion using a technique called fluidic self-assembly (FSA). The FSA process is found to be sensitive to the size, shape and orientation of the devices flowed. Larger devices (up to 1000 µm on a side) will move faster than smaller devices on an inclined, submerged plane. Rectangular devices with large length-to-width ratios and similar total mass, however, will also move more slowly than square devices. Rectangular and asymmetrically shaped devices will also orient as the slide down a submerged plane, and this has important implications for filling yield during FSA assembly. Lastly, increasing the temperature of the fluid decreased the viscosity and resulted in higher device velocities. We propose a boundary layer lubrication model to explain the motion and behavior of devices during fluidic self-assembly which is consistent with all of the experimental observations.