An automatic microassembly workcell for PMMA microfluidic chip packaging

To realize high-level Polymethylmethacrylate (PMMA) Micro-fluidic Chip (MFC) fabrication, microassembly must be precisely performed. The ability to package MFC with micron precision is a critical issue. This paper will report on a workcell developed for PMMA MFC alignment with micro assembly operations in volume MEMS devices production. The workcell consists of a 4-DOF (Degree of Freedom) high precision positioning unit, a split-field imaging unit, and an auxiliary unit. Zooming, focusing and illuminating of the optics can be adjusted automatically through image analysis to bring the alignment keys into view with high-level image quality. The work-cell reported in this paper integrates techniques of microscopic computer vision, precise positioning and pneumatic driving technique. With the substrate's external characteristic of "macro to micro" scale, the developed work-cell demonstrates the feasibility of using hybrid macro-manipulation and micromanipulation. Interactions between different units in the system and flexibility of accommodating multi-scale MEMS devices are considered in building the work-cell. Experimental results show that the average operation cycle time is 3.4 minutes; the microassembly accuracy of the system can reach 2.9 microns. The workcell can do micro-alignment assembly tasks efficiently and reliably for industrial applications.