Development of ultrasonic micro hot embossing technology

We succeeded in precise replication of patterns by impressing ultrasonic vibration besides heat and the loading force on the micro hot embossing (MHE). A Ni electroformed mold with micro patterns with seven sizes of entrance from 100 mu m(2) to 1.2 mm(2) was used. The experiment was executed on a polycarbonate (PC) sheet while impressing longitudinal wave of ultrasonic vibration at maximum amplitude of 1.8 mu m. The effect that bubble defect in the pattern was diminished or completely disappeared was observed by impressing ultrasonic vibration. Moreover, it was clarified that ultrasonic vibration assisted softened PC to move to the center of the pattern area in a mold. We found that the effect of ultrasonic vibration was well pronounced at low contact force. Perhaps very high contact force may be obstructing the progression of ultrasonic vibration. (c) 2007 Elsevier B.V. All rights reserved.