Effect of sonotrode design on the performance of the ultrasonic patterning process

The present study examines the use of ultrasonic waves in micro-pattern replication on polymer substrates. The ultrasonic patterning process was developed in order to use ultrasonic vibration energy to replicate the micro-patterns engraved on a sonotrode into the surface of a polymer substrate. To replicate the micro-patterns on the polymer substrate with high accuracy, the sonotrode should be designed to allow only longitudinal vibration, not transverse or twisting vibrations. In addition, the vibration magnitude should be maintained uniformly on the tip of the sonotrode in order to obtain uniform pattern replication. For this purpose, the sonotrode design is investigated through finite element analyses, from which the resulting natural frequency of the sonotrode can be adjusted to be within the desirable range. These FE analyses are performed for two types of sonotrodes, and the validity of the developed method is discussed from the ultrasonic patterning experiments using the optimally-designed sonotrodes.