Evaluation of asymmetric microfabricated surfaces using femtosecond laser process for microparts feeding

Previously, we found that an asymmetric microfabricated surface can feed microparts along using simple planar symmetric vibrations. Microparts move forward because they adhere to the asymmetric surface asymmetrically. To feed along 0402-type capacitors (size, 0.4 × 0.2 × 0.2 mm; weight, 0.1 mg), we used a slight stainless shim tape microfabricated by a femtosecond laser processing tool, specifically the double-pulsed femtosecond laser irradiation technique, to generate an asymmetric profile surface. We then evaluated the characteristics of the microfabricated surface, including the effects of decreased adhesion, the differences in profiles of the two inclined surfaces, the coefficients of friction in both the forward and backward directions, and the friction angle of the 0402-type capacitors in both directions. Using the results of feeding of these capacitors, we assessed the relationship between driving frequency and feeding velocity. We also assessed two other microfabricated surfaces generated by the single beam femtosecond laser diagonal irradiation technique. We evaluated the asymmetry of these microfabricated surfaces based on measurements using an atomic force microscope (AFM) system. We then performed feeding experiments of 0402-type capacitors with the same driving conditions using newly and previously generated surfaces. Experimental results were compared to assess the surface most appropriate for feeding 0402-type capacitors.