Finite element analysis of ultrasonic vibration-assisted microstructure hot glass embossing process

Abstract

Hot glass embossing is a novel technology to manufacture microtips for Field Emission Displays with high quality and low cost. This technology recently has been assisted by ultrasonic vibration. Previous studies showed that high energy of ultrasonic vibration would lead to the temperature rise inside the glass so that micro-formability of glass material has been especially improved efficiently. However, these findings were experimental only. Therefore, this work is aimed to utilise the proposed model in the previous study to analyse the shape of pyramid structures on K-PSK100 optical glass substrate during ultrasonic vibration-assisted hot glass embossing process. Microstructure hot embossing experiments were first conducted without and with the assistance of ultrasonic vibration (frequency of 35 kHz and amplitude of 3 μm). Three-dimensional simulations were then performed to predict the height of pyramids after hot embossing process. The consistency between simulations and experiments not only proved that ultrasonic vibration could increase the filling ability of glass material into microcavities up to 17% but also indicated the value of the proposed model in predicting the final shape of microstructures after ultrasonic vibration-assisted hot glass embossing process.

Keywords:

• Ultrasonic vibration
• hot glass embossing
• finite element analysis
• microstructures
• pyramid array

Acknowledgements

The authors would like to thank Calin Technology Co., Ltd., Taiwan for the providing Diamond-Like Carbon (DLC) coating layer for all embossing moulds so that sticking phenomenon between glass and moulds was eliminated during hot embossing experiments.

The authors also would like to thank Dr Chien-Yao Huang from Instrument Technology Research Center (ITRC), Hsinchu, Taiwan for supporting profile measurements of our glasses using Colour 3D laser microscope.

The authors’ thanks also go to would like to thank Mr Joe Lee from PerkinElmer Taiwan Corporation for performing Differential Scanning Calorimetry (DSC) for our K-PSK100 optical glass, by which structural relaxation properties were obtained.