• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1125-1128
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• 2001

A 110mm diameter aspheric metal secondary mirror for a test model of an earth observation satellite camera was fabricated by ultra-precision single point diamond turning(SPDT). Aluminum alloy for mirror substrates is known to be easily machinable, but not polishable due to its ductility. A harder material, Ni, is usually electrolessly coated on an Al substrate to increase the surface hardness for optical polishing. Aspheric metal secondary mirror without a conventional polishing process, the surface roughness of Ra=10nm, and the form error of Ra=λ/12(λ=632nm) has been required. The purpose of this research is to find the optimum machining conditions for reflector cutting of electroless-Ni coated Al alloy and apply the SPDT technique to the manufacturing of ultra precision optical components of metal aspheric reflector.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1889-1892
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• 2003

The fabrication of micro-size patterning on alumina substrate is generated by laser direct writing, which has high precision and selectivity of various laser beam energies. The depth and width of patterns is affected by laser parameter such as laser power, scan rate. Through the chemical and mechanical polishing Pd seeds was effectively got rid of alumina substrate for selectivity electroless Ni plating. Thermal treatment is good method for changing electrical property of conductor line, because the treatment can control of the grain size.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.118-121
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• 2003

The electrochemical behaviors of UBM nickel were investigated. Electrode potential has been changed with the surface composition. Zinc is dissolved into the solution immediately after immersion. Electrode potential has three distinct regions: Zinc dissolution region, transient region and nickel plating region. The effects additives on electrode potential and polarization curves were also investigated. The addition of suppressor lowered the current density which is related with deposition rate.

• 대한기계학회논문집A
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• 제32권5호
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• pp.419-423
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• 2008

A new polymer replication technology using ultrasonic vibration is proposed and demonstrated. A commercial ultrasonic welder has been used in this experiment. Two different types of nickel molds have been fabricated: pillar type and pore type microstructures. Polymethyl methacrlylate (PMMA) has been used as the replication material and the optimal molding time was 2 sec and 2.5 sec for pillar-type and pore-type micromolds, respectively. Compared with the conventional polymer micromolding techniques, the proposed ultrasonic micromolding technique has the shortest processing time. In addition, only contact area between micromold and polymer substrate is melted so that the thermal shrinkage can be minimized. The fabricated PMMA microstructures have been very accurately replicated without vacuum. The proposed ultrasonic molding technique is a good alternative for high volume production.

• 한국표면공학회지
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• 제28권4호
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• pp.199-206
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• 1995

A kinetic study on the electrodeposition of Ni-Zn-P ternary alloys onto a steel in chloride solutions was carried out using a rotating disc electrode. The coatings were characterized using SEM/EPMA and A. A. analysis. The results showed that the plating rates of three components were increased with applied potential, disc rotating speed and temperature. The activation energies of Ni, Zn and P of the coatings were 6.1, 5.1 and 8.0 kcal/mole respectively. Therefore, the deposition rates were controlled partly by surface electrochemical reaction and partly by mass transport. As the potential, temperature of bath and rotating speed of cathode disc were raised, the vol. % ratios of Ni and P of coating layer were increased but that of Zn decreased. The effect of coating parameters on the surface morphology was also examined.

• 한국표면공학회지
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• 제32권4호
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• pp.521-530
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• 1999

The corrosion resistance and the hardness of the tin-nickel alloy deposits electroplated in pyrophosphate bath were invesitigated according to electrolysis conditions and microstructure of the alloy. The weight loss of alloy deposits increased with the Sn content of single phase (Ni-Sn) alloy showing the lowest weight loss in the alloy with 54∼57wt% Sn. On the other hand, the multiphase alloy with 35∼42wt% Sn showed the highest one. The CASS test result was consistent with that of immersion test, and was good agreement with the corrosion data of polarization measurements. The hardness of alloy deposits decreased with the increase of Sn ratio in bath due to the grain size increase of the alloy. However, it increased noticeably with decreasing current density in the bath condition of low Sn ratio (0.1)

• 한국표면공학회지
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• 제24권4호
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• pp.206-214
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• 1991

In the basic study of selective electroless Ni plating of Si wafers, plating rate and physical properties are investigated to obtain optimum conditions of contact hole filling. Si wafers are excellently activated in the concentration of 0.5M IF, 1mM PdCl2, 2mM EDTA at $70^{\circ}C$, 90sec. The optimum condition of Ni-B deposition on p-type Si wafers is 0.1M NiSO4, 0.11M Citrate, $70^{\circ}C$, pH6.8, 8mM DMAB. The main factor in the sheet resistences variation of films is amorphous and on heat treating matrix was transformed into a stable phase (Ni+Ni3B) at $300-400^{\circ}C$. But pH or DMAB concentration in the plating solution doesn't play role of heat-affected phase change.

• 한국표면공학회지
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• 제21권2호
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• pp.39-46
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• 1988

Corrosion behavior of 5-26wt% Ni-Zn electrodeposited alloys was investigated by means of dipping electrochmical polarization measurement and galvanic coupling test. The weight loss and anodic polarization curve of coatings were measured by means of dipping and polarization measurement respectively. The galvanic protection effect of alloy coatings was measured by galvanic coupling test and the surface morpholgy of coatings was observed after corrosion testing. Our findings support thous of previous investigations showing that ${\gamma}$single phase coatings, while galvanic pprotection effect of dual phase coatings improved in comparison with ${\gamma}$single phase coating. The formation of colony in coating of ${\gamma}$and η+${\gamma}$ dual phsae caused the localized corrsion and increased the corrosion rate of the Ni-Zn coating.

• 한국표면공학회지
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• 제21권2호
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• pp.76-82
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• 1988

The bright nickel electroplatings were carried out the Watt bath containg a solobel saccharin as class I brightner and para substituted benzaldehydes as class II one. Extended Huckel MO calculation was done and polarization was measured to examine between $\pi$-electron density and the brightness. The correlation is also investigated between $\pi$-electron density of oxygen atom of aldehyde group and slope of polarization curve. As a result of the analysis of rate equation of nucleation, the surface energy of the deposited particle was obtained from the slope of the plot of $\ell$nI against 1/η2, and also the reat equation of nucleation found to influnced on the leveling on the basis of adsorption theory. We have proposed the general electroplating mechanism that is applied other to all other electroplating but nickel one. The above elucidated mechanism can be extended can be extended to the all electroplating other than bright nickel electroplating.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2224-2226
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• 2000

In this paper, we tried to figure out the residual stress of Electroless Nickel (EN) films as a function of process conditions: bath temperatures, pH values, and hypophosphorous acid concentrations. The residual stresses of EN films were in the range of - 4 MPa to 250 MPa depending on process conditions and they were very sensitive to phosphorous concentration in EN film and also hypophosphorous acid concentrations in EN bath.