Fabrication of microchannels by UV laser ablation

Abstract

This paper describes the fabrication of micro-channels in resin for micro-fluidic devices by a UV laser. Quartz wafers are coated with a 20μm thick BCB resin. Micro-grooves for micro-channels are fabricated into the BCB resin by a KrF excimer laser. The groove bottom is 100m wide at a pulse width of 20nsec, fluence of 1.3mJ/cm²/pulse, and overlap of 98.9%. The wafer surface serves as the bottom face of the groove. Moreover the side wall angle is 72°. Furthermore, the grooves are covered with laminate films to prevent leakage of the liquid samples. A thermoplastic film or a heat-hardening resin film is used as a laminate film. Laminating conditions are: roller temperatures of 120°C, pressure of 0.8MPa, and laminating speed of 0.2m/min. The thermoplastic film coats the groove perfectly. On the contrary, the heat-hardening film does not sag into the groove, resulting in an open-are cross-sectional ration of 80%. Furthermore, the open-area-ratio becomes 100% through a heat-curing process at a temperature of 120°C for 30min. The through holes are made in the laminate film by a KrF excimer laser. Inlet pipe for a micro-pump are inserted into the hole.