Improvement of machining quality of copper-plated roll mold by controlling temperature variation

Micro prism film used in LCD industry can be manufactured by roll to roll method with copper-plated roll mold. As copper-plated roll mold is getting larger, pitch error is getting severer. The pitch error drops the quality of micro prism film. The main cause of the pitch error was investigated during machining large roll mold whose machined length was 1 200 mm. The temperature of machining system was elevated during machining roll mold, and this elevation induced thermal expansion of the system. The temperature variation around the roll mold also made thermal expansion of the roll mold. The amount of thermal expansion had strong relationship to the amount of pitch error. Therefore, the roll mold was machined after warming-up of machining system and precise temperature controller around copper-plated roll mold was installed, which minimized the temperature variation. Finally, precise micro prism patterns without pitch error were machined on the large roll mold.

Wear characteristics of Ⅴ shape diamond tool for micro prism pattern with Al alloys

The ultra-precision machining process using a single crystal diamond tool has been mainly used for machining molds of optical components.Since the micro patterns of various shapes having excellent surface roughness can be machined by using ultra-precision machine tools,the micro pattern on a large light guide plate (LGP) is mainly machined using a diamond tool.The tool wear occurs due to long machining distances and time while machining a large-area LGP mold.The deformation and dimensional error of micro pattern are caused by tool wear,as a result,the light efficiency of LGP declines.The characteristics of tool wear should be analyzed in order to precisely machine large-area LGP mold from all sorts of materials.The experiments were performed in order to compare wear characteristics of a V90° diamond tool using Al3003,5052,6061 and 7075.The prism pattern of depth 10 μm was machined in order to analyze characteristics of tool wear according to machining distances (0.5,1 and 1.5 km).The effects of tool wear on pattern shape were analyzed by applying overlapped cutting depths (Rough machining is (10+8+7) μm and Finish machining is (5+3+2+1) μm) by continuously machining a prism pattern of W shape of 25 μm in depth.

Highly impermeable and flexible silica encapsulation films synthesized by sol-gel process

Silica thin films synthesized sol–gel process are proposed as flexible encapsulation materials.A sol–gel process provides a dense and stable amorphous silica structure,yielding an extremely high elastic deformation limit of 4.9%and extremely low water vapor transmission rate(WVTR)of 2.90×10^(−4)g/(m^(2)∙day)at 60℃and relative humidity of 85%.The WVTR is not degraded by cyclic bending deformations for the bending radius corresponding to a tensile strain of 3.3%in the silica encapsulation film,implying that the silica thin film is robust against the formation of pinhole-type defects by cyclic bending deformations.Flexible organic solar cells encapsulated with the silica films operate without degradation in power conversion efficiency for 50,000 bending cycles for a bending radius of 6 mm.