Programmable Self-assembly For Microsystem Integration

Abstract

This dissertation studies and improves upon template-based self-assembly processes as a suite of techniques for microsystem integration. We first provide an updated definition for microscale self-assembly, and provide a framework that separates all self-assembly processes into three distinct phases which can be independently analyzed. A catalyst-enhanced self-assembly process is then presented, wherein non-participating `catalyst' components are introduced to a dry-environment batch-assembly process, demonstrating 25 - 50% reduction in acceleration needed to trigger part motion and up to four times increase in concentration of parts in motion due to addition of catalysts. The presence of catalytic parts allows stochastic part-to-trap assemblies to be performed at lower accelerations than without, and thus allow said assemblies to be performed further from the acceleration-levels required to free trapped parts; this reduces the probability of part-disassembly, thus improving assembly yield. A model from chemical kinetics theory is adapted for the analysis of this catalyst-enhanced self-assembly process. A variation on the prevalent methodology of driving a stochastic assembly process, using vibrations perpendicular to the assembly surface, is then presented. Using a modified actuator that introduces agitations that are in the plane of the assembly surface, unprecedented control of micropart-motion has been achieved; of note, components can be reliability induced into a "walking mode", where components are moved across surfaces in predetermined directions with a surface-hugging motion. Walking modes enables parts to be moved across surfaces and into binding sites, but do not cause trapped components to disassemble due to the suppression of out-of-plane agitation. Repeatable and programmable complete delivery of components into arrays of traps is achieved in open loop and feedback-enhanced configurations. The theoretical study of this template-based assembly method is performed with (370 × 370 × 150 µm<super>3</super>) test components, and walking modes are statistically characterized and a chemical kinetics inspired model is developed. Said self-assembly process is then applied on the assembly of 01005 (0.016" × 0.008", 0.4 mm × 0.2 mm) surface mount technology resistors and capacitors, demonstrating the transportation, self-alignment, and adherence phases of our template-based assembly process. Finally, the magnetically aided assembly of 01005 surface mount components in a vertical pose is studied by adapting the visual-feedback systems used throughout the thesis work. Electrical performance has been verified, and our process is demonstrated to be competitive against integrated passive elements in terms of area-footprint and capacitive and resistive property-tolerances.