Nondestructive inspection of patterns formed on inner surfaces of small diameter pipes
Inspection of patterns formed on inner surfaces of copper pipes with a small diameter of 2 mm was investigated. At first, space patterns with widths of 20-30 μm were lithographically formed using a handmade laser-scan exposure system. The exposure system was equipped with a monitoring system of a laser beam spot irradiated on the inner surface of pipe for the exposure. Pattern inspection was executed utilizing this monitoring system. In the case of exposure for patterning, the beam monitor was used for confirming the position and size of the laser beam. However, being prevented by the bright beam spot, background views were not clearly observed. For this reason, the pinhole that is initially inserted for reshaping the laser beam and making an appropriately small spot was removed, and the brightness of the beam spot was mitigated. In addition, inspected camera images were stored as video images in a personal computer using a video capture. As samples for the inspection, space patterns in resist films and groove patterns etched in copper pipes were used. As a result, resist space patterns were observed quite clearly, and pattern widths were measurable. In addition, the measured pattern widths almost agreed with the ones measured using a scanning electron microscope after cutting a half of the pipe off. On the other hand, etched groove patterns were not so clear as resist patterns. However, it was clarified that fatal pattern defects such as kinks, shifts, and breaks were detected, if the pattern images stored in the computer were carefully investigated. The new nondestructive inspection method is effective.
Fabrication of precise copper micro-coils using electrolytic etching
Precise and homogeneous copper micro-coils were fabricated using electrolytic etching in aqueous solution of sodium chloride and ammonium chloride. It was clarified that the etching rate was hardly influenced by the resist pattern thickness and the etching voltage, but only depended on the helical space pattern width. Start and stop of the etching was exactly controlled by switching on and off the power supply circuit, and the etching was practiced under the room temperature without heating the specimens. The sidewall surfaces of the etched coils were very much smoother than those of the coils fabricated by the conventional chemical etching, and very favorable coil width homogeneity was obtained even for narrow space patterns with a width around [email protected]
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.