Hot embossing precise structure onto plastic plates by ultrasonic vibration

Abstract

Hot embossing achieves excellent performance in replicating precise features onto large plastic plates. It has become a popular approach because microstructures in master molds can now be easily made using Lithographie GaVanoformung Abformung (LIGA) and micro-electro-mechanical-system (MEMS) technologies. However, there are still some unsolved problems that confound the overall success of this technology. Long cycle times caused by conventional electric or hot oil heating is one of them. This research attempted to use ultrasonic vibration as a heat generator for hot embossing. The first part of this study investigated the replication capacity of ultrasonic-heating embossing of both amorphous and semicrystalline plastic plates; the second part of this study examined the effects of various ultrasonic vibration parameters on the contour of replicated structure; and the third part of this study identified the relative significance of all these parameters on molded part quality. In addition, the temperature profiles at different depths of the embossed plates by ultrasonic vibration were measured. The experimental results in this study suggest that ultrasonic vibrated hot embossing could provide an effective way of molding precise structure onto polymeric plates. This would provide significant advantages in terms of a shorter cycle time as well as improved product quality. POLYM. ENG. SCI., 45:915-925, 2005.

Optimization of Ultrasonic Imprinting Using the Response Surface Method

“…상기 제품의 미세패턴 성형을 위해 핫엠보싱(Hot embossing), 사 출성형(Injection molding) 등의 공정이 사용되고 있 는데 [1,2], 패턴의 크기가 작아질수록 패턴의 전사 성을 높이기 위해 높은 금형온도가 요구되고 결 과적으로 생산성이 저하되는 문제점이 있다 [3]. 최 근에는 초음파 진동에너지를 핫엠보싱 공정 [4,5] 이나 마이크로 사출성형 [6] …”

Heat generation and distribution in the ultrasonic hot embossing process

“…Several papers have been published on ultrasonic hot embossing and its variants Liu and Dung 2005;Mekaru et al 2007a, b;Khuntontong et al 2008;Yu et al 2009;Lee et al 2010;Altmann et al 2012;Šakalys et al 2015;Planellas et al 2014), but up to now only few investigations have been performed on the physical processes during fabrication. Liu and Dung measured the temperature inside of a polymethylmethacrylate (PMMA) plate, 2 mm in thickness, with thermocouples inserted into drilled holes and discovered that in less than 0.5 s temperatures were rising up to 200 °C (Liu and Dung 2005).…”

“…Liu and Dung measured the temperature inside of a polymethylmethacrylate (PMMA) plate, 2 mm in thickness, with thermocouples inserted into drilled holes and discovered that in less than 0.5 s temperatures were rising up to 200 °C (Liu and Dung 2005). Wise measured the temperatures above and aside of an energy director with thermocouples during ultrasonic welding and recorded temperatures as high as 165 °C (Wise 2010).…”

Ultrasonic Hot Embossing

“…Two decades later, the development of micro patterning of polymer plates started [6,7] and in 2008 there was the first publication on a micro system fabricated by ultrasonic hot embossing [8].…”