• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.2
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• pp.69-76
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• 2001

The purpose of this research is to investigate the thermal performance of embossing surface sandwich panel and flat surface sandwich panel. To do this research, thermal performances in summer season at the six points of embossing surface sandwich panel and flat surface sandwich panel are investigated focusing on the temperature. Three kinds of embossing surface sandwich panel and one kind of flat surface sandwich panel are used for this research. At the same size of sandwich panel, the average temperature differences of flat surface sandwich panel between average temperature at the 0.5 mm below copper plate and average outside air temperature and surface temperature are higher than those of embossing surface sandwich panel. The average heat transfer rate of flat surface sandwich panel in higher than that of embossing surface sandwich panel. More study will be needed about the size of diameter and height of embossing, and materials of embossing surface sandwich panel.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.917-924
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• 2000

The purpose of this research is to investigate the thermal performance of embossing surface sandwich panel and flat surface sandwich panel during the summer. To do this research, thermal performances in summer season at the six points of embossing surface sandwich panel and flat surface sandwich panel are investigated focusing on the temperature. Three kinds of embossing surface sandwich panel and one kind of flat surface sandwich panel are used for this research. At the same size of sandwich panel, the average temperature differences of flat surface sandwich panel between average temperature at the 0.5 mm below copper plate and average outside air temperature and surface temperature are higher than those of embossing surface sandwich panel. The average heat transfer rate of flat surface sandwich panel is higher than that of embossing surface sandwich panel. More study will be needed about the size of diameter and height of embossing, and materials of embossing surface sandwich panel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.223-226
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• 2004

Injection molding using plastic materials was expected to mass production of structure with nano pattern for low cost phase. The PDMS mold was produced easily and uniformly by using thermal embossing. Quartz master for embossing method was made using electron beam lithography it had 100-500 nm size of line and dot type. The PDMS mold was produced after a brief hardening process and the master removal. The results show that various patterns are successfully fabricated the nano scale.. The replicated mold would be useful a stamper fabrication for injection molding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.228-232
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• 2003

Mircolens and microlens arrays are realized using a novel fabrication technology based on the exposure of a resist, usually PMMA, to deep X-rays and subsequent thermal treatment. Hot embossing process is also studied for mass production. The fabrication technology is very simple and produces microlenses and microlens arrays with good surface roughness of several nm. The molecular weight and glass transition temperature of PMMA is reduced when it is irradiated with deep X-rays. The microlenses were produced through the effects of volume change, surface tension. and reflow during thermal treatment of irradiated PMMA. A hot embossing machine is designed and manufactured with a servo motor transfer system. The hot embossing process follows the steps of heating mold to the desired temperature, embossing a mold insert on substrate. cooling mold to the de-embossing temperature. and de-embossing. Microlenses were produced with diameters ranging from 30 to 1500 ${\mu}{\textrm}{m}$. The surface X-ray mask is also fabricated to realize microlens arrays on PMMA sheet with a large area.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.627-628
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1140-1144
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• 2005

A plastic-based CE (capillary electrophoresis) microchip was fabricated by hot embossing process. A Si mold was made by wet etching process and a PMMA wafer was cut off from 1mm thick PMMA sheet. A micro-channel structure on PMMA substrate was produced by hot embossing process using the Si mold and the PMMA wafer. A vacuum assisted thermal bonding procedure was employed to seal an imprinted PMMA wafer and a blank PMMA wafer. The results of microscopic cross sectional images showed dimensions of channels were well preserved during thermal bonding process. In our procedure, the deformation amount of bonding process was below 1%. The entire fabrication process may be very useful for plastic based microchip systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.669-670
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• 2006

• Journal of the Korean Vacuum Society
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• v.13 no.1
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• pp.34-38
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• 2004

Hot embossing master is indispensable for the fabrication of polymeric optical waveguides using hot embossing technology. Sidewall roughness of silicon master is directly related to optical loss of optical waveguides In this paper, a silicon master was fabricated by using a deep-RIE process. Additionally, thermal oxidation followed by oxide removal was carried out to minimize etched Si sidewall roughness. Thermal oxidation and oxide removal were performed with $H_2O_2$ atmosphere at $1050^{\circ}C$ and $NH_4$F:HF=6:l BOE, respectively, for the oxide thickness of 400$\AA$, 1000$\AA$, 3000$\AA$, 4500$\AA$, 5600$\AA$ and 6200$\AA$. The sidewall roughness was characterized by SEM and SPM-AFH measurements. We found that the roughness was improved from 12nm (RMS) to 6nm (RMS) for the scalloped sidewall and from 162nm (RMS) to 39nm (RMS) for the vertical striation sidewall, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.191-194
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• 2007

In hot embossing lithography which has shown to be a good method to fabricate polymeric patterns for IT and bio components, it is very important to determine the proper process conditions of pressure, temperature, and time. It is also a key factor for predicting the optical properties of final product to calculate residual stress distribution after the embossing process. Therefore, to design the optimum process with right conditions, the ability to predict viscoelastic behavior of polymer during and after the hot embossing process is required. The objective of the present investigation is to establish simulation technique based on constitutive modeling of polymer with experiments. To analyze deformation behavior of viscoelastic polymer, the large strain material properties were obtained from quasi-static compression tests at different strain rates and temperatures and also stress relaxation tests were executed. With this viscoelastic material model, finite element simulation of hot embossing was executed and stress distribution is obtained. Proper process pressure is very important to predict the defect and incomplete filling.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.3
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• pp.199-203
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• 2017

Hot embossing techniques are used to engrave patterns on plastic substrates. Roll based hot embossing uses a heated roll for a continuous process. A heated roll with relief patterns is impressed on a preheated plastic substrate. Then, the substrate is cooled down quickly to prevent thermal shrinkage. The roll speed is normally very slow to ensure substrate temperature increase up to the glass transition temperature. In this paper, we propose a noncontact preheating technique using focused infrared light. The infrared light is focused as a line beam on a plastic substrate using an elliptical mirror just before entering the hot embossing roll. The mid range infrared light efficiently raises the substrate temperature. For preliminary tests, substrate deformation and temperature changes were monitored according to substrate speed. The experiments show that the proposed technique is a good possibility for high speed hot embossing.