Evaluation of feeder surface materials for microparts feeding using an asymmetric fabricated surface with symmetric vibrations

We have previously shown that microparts can be fed along an asymmetric microfabricated surface using simple planar symmetric vibrations. Microparts move forward because they adhere to the microfabricated surface asymmetrically. We have also described the effects of sawtoothed surfaces on the movement of submillimeter microparts; for example, 0603 (size, 0.6 × 0.6 × 0.3 mm; weight, 0.3 mg) and 0402 (size,0.4 × 0.2 × 0.2 mm; weight, 0.1 mg) capacitors. In the present work, we studied the effects of feeder materials on the feeding of single layer chip capacitors (size, 0.25 × 0.25 × 0.35 mm; weight, 0.06 mg), We found that the motion of submillimeter microparts was affected not only by inertia but also by adhesion due to electrostatic, van der Waal´s, and intermolecular forces, and to surface tension. These effects are dependent on the two materials that are in contact with each other. The four materials selected for feeder surfaces were microfabricated so that periodic sawtooth structures were present on their surfaces. Asymmetry catacteristics of their surfaces were evaluated by the differences in profiles of the two inclined surfaces, and also by the friction angle of microparts in both the forward and the backward directions. We then assessed micropart feeding using these surfaces, as well as the relationship between feeding velocity and vibration frequency. By comparing the feeding velocity on each feeder surface, we assessed the effects of feeder surface materials on the feeding of microparts.