Jeongjin Kang

Effects of adding injection–compression to rapid heat cycle molding on the structure of a light guide plate

This study investigates the effects of adding injection–compression to rapid heat cycle molding (RHCM) (rapid heat cycle injection–compression molding (RICM)) on the physical quality and optical anisotropy of a molded light guide plate (LGP). Transcription ratio of microstructure, uniformity of part thickness and birefringence were experimentally evaluated on a 7 inch LGP of nominal thickness of 1.12 mm (including a microstructure array of 30 µm diameter and 14 µm height). The designed mold was equipped with rapid heating and compressing facilities and a microstructured nickel stamper was fabricated by UV LIGA process. In addition, to investigate the efficacy of RICM, experiments involving conventional injection molding (CIM), ICM, and RHCM were conducted in parallel with RICM using the same mold. RHCM and RICM yielded excellent transcription ratios for the microstructure, while CIM and RICM provided high thickness uniformity and low birefringence. Thus, RICM obtains high transcription ratio of microstructure, uniform thickness and low birefringence.

Comparison of injection molding and injection/compression molding for the replication of microstructure

Because of increasing interest in the functional surfaces including micro- or nano-patterns, the mass production of such surfaces has been actively researched. Both conventional injection molding (CIM) and injection/compression molding (ICM) of micro-patterns were investigated in the present study. The molding subject is a multi-scale structure that consists of a macro-scale thin plate and micro-scale patterns formed regularly on its surface. The transcription ratios of micro pattern made by CIM and ICM for different flow length were experimentally measured, and the origin of the obtained results was identified through numerical analysis. It was found that the cavity pressure and polymer temperature are the most important factors for micro-pattern filling; in particular, the polymer temperature is the key factor determining the transcription ratio. It was also found that the difference in CIM and ICM micro-pattern transcription ratios originates from the differences in the cavity pressure history if other molding conditions are the same.

Fabrication and Characterization of Thermally Actuated Bimorph Probe for Living Cell Measurements with Experimental and Numerical Analysis

This paper deals with a novel structure for single-cell characterization which makes use of bimorph micro thermal actuators combined with electrical sensor device and integrated microfluidic channel. The goal for this device is to capture and characterize individual biocell. Quantitative and qualitative characteristics of bimorph thermal actuator were analyzed with finite element analysis methods. Furthermore, optimization for the dimension of cantilevers and integrated parallel probe systems with microfluidic channels is able to be realized through the virtual simulation for actuation and the practical fabrication of prototype of probes. The experimental value of probe deflection was in accordance with the simulated one.

Optical Analysis for Designing a Planar Solar Concentrator Based on Light Guide System

Recently, an optics-based concentrator for solar concentration has been a key issue in development of photovoltaic systems. In the present study, a new, simple, easily producible planar concentrator based on a light guide system is proposed. In this device, solar light is concentrated by microprism optical patterns guiding the light, mainly through total reflection and refraction. The main design variables of the concentrator are the geometric concentration ratio () and the and of the microprism pattern. Ray tracing was simulated using commercial software, SPEOS, and the optical efficiencies of the light guide solar concentrator were predicted in each case. The predicted maximum optical efficiencies are 65.60%, 54.78%, and 46.78%, respectively, for values of 4, 5, and 6. The variation of the optical efficiencies according to , , and the incline angle of the incident light were predicted.

Silicone Injection Mold & Molding Technology for Super-hydrophobic Curved Surface

In this study, silicone injection molding technology with curved thermoplastic insert was developed to produce super-hydrophobic surface. Thermoplastic insert part and injection mold design of base plastic cover were performed to produce cost effective hydrophobic surface part. An optimization process of part thickness for thermoplastic insert part was performed with transient thermal analysis under silicone over-molding process condition. Structural thermal analysis of silicone injection mold was also performed to obtain uniform temperature condition on the surface of micro-patterned mold core. Super-hydrophobic surface for the silicone injection molded part with thermoplastic insert could be verified from the measurement of contact angle. It was shown that the averaged contact angle was over 140°.

Nano patterning of P3HT by thermal molding with a nickel stamp replicated from anodic aluminum oxide

One of electron donors in organic photovoltaics, P3HT nano patterns of diameter 70∼75 nm, height 40∼55 nm and pitch 95∼105 nm were thermally molded on the area of 18 × 26 mm2. They were molded by thermal molding with a nickel stamp as a mold. The nickel stamp was fabricated by nickel electroforming using a well-arrayed anodic aluminum oxide(AAO) as an original template. The study on the nano patterning of P3HT by thermal molding was performed according to the variations of temperature, molding pressure, and processing time.

Fabrication of Partition Wall for Solar Cell by Hot Embossing

Hot embossing technology, one of nanoimprint lithography (NIL) techniques, has been getting attention as an alternative candidate of next generation micro-patterning technologies by the advantages of simplicity and low cost compared to conventional photo-lithographies. For this study of fabrication of partition wall for polymer solar cell, The manufacturing process is made up of three stages as in the following: (i) the stage of lithography process, (ii) the stage of electro-plating process for mold, and (iii) the stage of hot embossing process. As a result, we made 6 inch Ni-mold and hot embossed partition wall for polymer solar cell.