Submillimeter Micropart Feeding Along an Asymmetric Femtosecond-Laser-Microfabricated Surface

Femtosecond laser technology forms minute, stable gratings on such materials as silicon and stainless steel. Forming a periodic structure on the surfaces of sliding parts improves tribology characteristics because adhesion decreases with reductions in area of contact. Double-pulsed femtosecond laser irradiation generates periodic structures with asymmetric profiles, along which, as we have shown elsewhere, microparts such as ceramic chip capacitors and resistors can be fed using simple symmetric planar vibration. Microparts move unidirectionally because they adhere to these surfaces asymmetrically. In testing the feasibility of feeding 0402 capacitors 0.4 × 0.2 × 0.2 mm in size and 0.1 mg weighting along an asymmetric surface fabricated using double-pulsed femtosecond laser irradiation, we evaluated differences in the profiles of the two inclined surfaces, effects of decreased adhesion, the forward and backward coefficient of friction, and the bidirectional friction angle of 0402 capacitors. Based on feed experimental results, we assessed the relationship between drive frequency and feed velocity and, by calculating variations in feed velocity, feed stability.