• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.143-144
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• 2006

In this paper, we proposed XP KMPR-1050 negative tone resist to replace SU-8 resist for multi-layer micro-structures and thick plating mold fabrication using UV-LIGA process. XP KMPR resist proposed in this paper can be easily striped using a common stripping solution such as NMP without damage of micro-structure. The conditions for the fabrication of XP KMPR micro-structure were optimized by adjustment of exposure and post-exposure bake(PEB). The $140{\mu}m$ -thick and an aspect ratio at least 10 micro-structure and multi-layer structures were successfully fabricated through the process conditions. Through-mold electroplating and PR striping of XP KMPR has been successfully demonstrated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.46-52
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• 2006

The effects of surface treatment on the hydrogen storage properties of a $Mg_2Ni$ alloy particle were investigated by the microvoltammetric technique, in which a carbon-filament microelectrode was manipulated to make electrical contact with the particle in a KOH aqueous solution. It was found that the hydrogen storage properties of $Mg_2Ni$ at room temperature were improved by the surface treatment with a nickel plating solution. The sodium salts(sodium phosphate and sodium dihydrogen citrate) contained in the nickel plating solution made the alloy form an amorphous-like state, resulting in an improved hydrogen charge/discharge capacity at room temperature as high as about 150[mAh/g] from the original value of 17[mAh/g]. Potential-step experiment was carried out to determine the apparent chemical diffusion coefficient of hydrogen atom($D_{app}$) in the alloy. Since the alloy particle we used here was a dense, conductive sphere, the spherical diffusion model was employed for data analysis. $D_{app}$ was found to vary the order between $10^{-8}{\sim}10^{-9}[cm^2/s]$ over the course of hydrogenation and dehydrogenation process.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.3
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• pp.27-33
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• 2008

With increasing use of portable appliances such as PDA and cellular phone, changing environment of applications requires higher solder joint reliability. The ENIG (Electroless Nickel Immersion Gold) process has been widely used for fine pitch SMT (Surface Mount Technology) and BGA (Ball Grid Array) packaged devices due to its benefits including excellent solderability, high uniformity and substantial legibility throughout the packaging process. Its brittle fracture of solder, however, has received increasingly attentions. It was Down that fracture brittleness is mainly related with black pad resulting from galvanic nickel corrosion and P-enriched layer formation between the IMC (Intermetallic Compounds) and electroless nickel layer. Theoretically, smooth electroless Ni layer was blown to have a advantages in minimizing the black pad phenomenon by uniform solution exchange during immersion gold plating. Nevertheless, how to control the surface morphology of electroless Ni layer has been hardly blown. This study investigates an effect of surface morphology of Cu underlayer on surface morphology of electroless Ni layer. To obtain various kinds of surface morphology of Cu layer, two types of Cu etching chemical and a number of Cu etching treatment were applied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1254-1260
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• 2000

There have been many developments in super precision working technique and working method up to, now. But, it is very difficult to evaluate working surface accurately without the technicians experience and judgment. Surface roughness tester using stylus was used to measure surface condition generally But this method is not so desirable because of damage on test piece caused by contact between the workpiece and the stylus sensor. As a result, non-contact method was known as a good way to carry, out this process without damage. However, this is a difficult one among the various measuring methods. So we are tying to suggest a new method using texture analysis through image processing to get a surface information in worked test piece. Co-occurrence matrix using difference of gray levels between a pixel and its neighboring one was used to study behavior of surface roughness and to J acquire data for analysis. Standard specimen was adapted to verify this research. We suggest texture information method in order to evaluate surface state for the best measurement system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.11
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• pp.1135-1140
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• 2012

Two-step metallization processes have been proposed to achieve high-efficiency silicon solar cells, where the front-side grids are formed by silver plating after the formation of a nickel seed layer with a mask. Because the conventional mask patterning process is performed by an expensive selective printing method using either UV resist or phase change ink, however, the combination of a simple coating and laser-selective ablation processes is proposed in this study as an alternative means. As a masking material, the solar cell wafer was coated with either inexpensive wax having a low melting temperature or a fluorocarbon solution, and then, an electrode image was patterned by selectively removing the masking material using the laser. It was found that the fluorocarbon coating was not only superior to the wax coating in terms of pattern uniformity but it also increased the efficiency of the solar cell by 0.16%, as confirmed by statistical f and t tests.

• Smart Structures and Systems
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• v.26 no.4
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• pp.507-520
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• 2020

In order to achieve effective corrosion monitoring of buried metal pipelines, a Novel nondestructive Testing (NDT) methodology using ultra-long (250 mm) Polymer Optical Fiber (POF) sensors coated with the Fe-C alloy film is proposed in this study. The theoretical principle is investigated to clarify the monitoring mechanism of this method, and the detailed fabrication process of this novel POF sensor is presented. To validate the feasibility of this novel POF sensor, exploratory research of the proposed method was performed using simulated corrosion tests. For simplicity, the geometric shape of the buried pipeline was simulated as a round hot-rolled plain steel bar. A thin nickel layer was applied as the inner plated layer, and the Fe-C alloy film was coated using an electroless plating technique to precisely control the thickness of the alloy film. In the end, systematic sensitivity analysis on corrosion severity was further performed with experimental studies on three sensors fabricated with different metal layer thicknesses of 25 ㎛, 30 ㎛ and 35 ㎛. The experimental observation demonstrated that the sensor coated with 25 ㎛ Fe-C alloy film presented the highest effectiveness with the corrosion sensitivity of 0.3364 mV/g at Δm = 9.32 × 10^-4 g in Stage I and 0.0121 mV/g in Stage III. The research findings indicate that the detection accuracy of the novel POF sensor proposed in this study is satisfying. Moreover, the simple fabrication of the high-sensitivity sensor makes it cost-effective and suitable for the on-site corrosion monitoring of buried metal pipelines.

• Resources Recycling
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• v.28 no.1
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• pp.3-14
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• 2019

Copper is used in many electronic components and construction parts due to its excellent electrical conductivity and heat transfer characteristics, and also used for pre-plating for double layer coating such as nickel, so that copper is an essential material in modern industry. Despite the expected increase of usage and importance on wiring, sensors and data equipment in the next generation industries, it is hard for securing stable copper supply and resource management resulting from the copper prices are fluctuating owing to the economic crisis in Europe, the low economic growth trend in China, and President Trump's commitment to public industrial facilities investment in U.S.. Since most of the domestic copper consumption is used by electrolytic copper cathode, we studied not only copper recycling technology which is being commercialized but also current research trend under the research stage. This study aims to examine the characteristics of each process and the areas where future recycling technology development is required.