• 마이크로전자및패키징학회지
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• 제24권3호
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• pp.77-81
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• 2017

Pulse electroplating of Ni-P alloy was studied to fulfill the material requirement to the advanced vertical probe tip in wafer probe card. The major concerns are for the electrical conductivity and yield strength. Plating parameters such as current density, duty cycle and solution components were examined to obtain the nanocrystal structure and proper percentage of phosphorus, leading to how to control the nanocrystal grain growth and precipitation of $Ni_3P$ after heat treatment. Among the parameters, the amount of phosphorus acid was the main factor affecting on the grain size and sheet resistance, and the amount of 0.1 gram was appropriate. Since hardness in Ni-P alloy is increased by as-plated nanocrystal structure plus precipitation of $Ni_3P$, the concentration of P less than 15 at% was better choice for the grain coarsening without minus in hardness value. The following heat treatment made grain growth and dispersion of precipitates adjustable to meet the target limit of resistance of $100m{\Omega}$ and hardness number of over 1000Hv. The Ni-P alloy will be a candidate for the substitute of the conventional probe tip material.

• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.549-558
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• 2018

The overall efficiency depend on the overpotential of the oxygen evolution reaction in alkaline water electrolysis. Therefore, it is necessary to research to reduce the oxygen evolution overpotential of electrodes. In this study, Ni-Zn-Fe electrodes were prepared by electroplating and the surface area was increased by Zn leaching process. Electroplating variables were studied to optimize the plating parameters(electroplating current density, pH value of electroplating solution, Ni/Fe content ratio). Ni-Zn-Fe electrode, which is electroplated in a modified Watts bath, showed 0.294 V of overpotential at $0.1A/cm^2$. That result is better than that of Ni and Ni-Zn plated electrodes. As the electroplating current density of the Ni-Zn-Fe electrode increased, the particle size tended to increase and the overpotential of oxygen evolution reaction decreased. As reducing pH of electroplating solution from 4 to 2, Fe content in electrode and activity of oxygen evolution reaction decreased.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.67-71
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• 2015

Pulse electroplating was studied to form nanocrystal structure effectively by changing plating current density and duty cycle. When both of plating current density and duty cycle were decreased from $100mA/cm^2$ and 70% to $50mA/cm^2$ and 30%, the P content in the Ni matrix was increased almost up to the composition of $Ni_3P$ compound and the grain growth after annealing was retarded as well. The as-plated hardness values ranging from 660 to 753 HV are mainly based on the formation of nanocrystal structure. On the other hand, the post-anneal hardness values ranging from 898 to 1045 HV, which are comparable to the hardness of hard Cr, are coming from how competition worked between the precipitation of $Ni_3P$ and the grain coarsening. According to the ANOVA and regression analysis, the plating current density showed more strong effect on nanocrystal size and film hardness than the duty cycle.

• 한국표면공학회지
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• 제43권2호
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• pp.57-63
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• 2010

In this study, thermal stability of the mechanical properties of Ni-P-B and Ni-P-Fe layers electroplated on Alloy 600 material was evaluated by measuring their microhardness, tensile strength, and elongation after heat treatment at $325^{\circ}C$ and $400^{\circ}C$. According to the results, there was no noticeable change in microhardness of the two electrodeposits before and after heat treatment at the temperatures for 30 days. In the case of a Ni-P-B electrodeposit, ultimate tensile strength (UTS) slightly increases with heat treatment time, while its elongation decreases, showing good thermal stability in the mechanical properties at high temperature. On the other hand, UTS and elongation of Ni-P-Fe decrease with heat treatment time, which is very unusual observation. This result was attributed to the bad microstructure of Ni-P-Fe having many defects in the deposit formed early stage of an electroplating process and their redistribution to link to become large ones during heat treatment.

• 마이크로전자및패키징학회지
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• 제26권4호
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• pp.133-140
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• 2019

열 사이클 조건이 전해 Cr/Ni-P 이중도금 시편의 접합강도 및 균열성장거동에 미치는 영향을 분석하였다. 전해 Ni-P 도금층을 열처리를 통해 결정화 시킨 후 전해 Cr 도금 후 한번 더 열처리한 결과, Cr/Ni-P 계면에서 상호확산으로 인해 Cr-Ni 고용체 band layer가 관찰되었다. 열 사이클 전 접합강도는 25.6 MPa이였으나, 1,000사이클 후 Cr 도금층의 균열 밀도 및 표면 거칠기 증가로 인해 도금층과 접착제 사이의 기계적 고착효과가 향상되어 접착제와 Cr 도금층 사이에서 박리되었고, 접합강도는 47.6 MPa로 점차적으로 증가하였다.

• Corrosion Science and Technology
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• 제2권4호
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• pp.197-201
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• 2003

In this study, Ni-P layers were electroplated on the surface of stainless steel in order to investigate the effects of an additive and agitation on their mechanical properties and microstructure. The concentration of the additive in the plating solution increased, the pores formed in the layer decreased, while the residual stress developed in the layers during electroplating increased. Agitation of the solution during electroplating was observed to force to increase local pores in the layer, which lowers its tensile properties. Grain growth was suppressed due to very fine $Ni_3P$ precipitates formed at its grain boundaries during heat treatment at $343^{\circ}C$ for 1 hr in air.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.276-279
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• 2004

The factors affecting Ni-Co alloy electroforming were investigated to determine the optimum bath composition and electroplating parameters, like pH, temperature, and current density, suitable for high speed fabrication of a micro mold with longer lifetime. To obtain alloy deposits having uniform thickness and composition, electroplating parameters were finely tuned with home-made electroforming apparatus. Ni-Co alloy deposits had linearly increased Co with $Co^{2+}$ ion concentration in electroplating bath, and showing $412H_v$ of Victors hardness at $23wt\%$ of Co content. For Ni-Co alloy, sulfonate and diol related organic additives were very effective to alleviate its residual stress and surface roughness. The maximum deposition rate was $106{\mu}m/hr$ at 10ASD and the tensile strength of alloy deposit was 2 times larger than that of Ni only case.

• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.361-364
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• 2008

Tips of probe card were fabricated using MEMS technology. P-type silicon wafer with $SiO_2$ layer was used as a substrate for fabricating the probe card. Ni-Cr and Au used as seed layer for electroplating Ni were deposited on the silicon wafer. Line patterns for probing devices were formed on silicon wafer by electroplating Ni through mold which formed by MEMS technology. Bridge structure was formed by wet-etching the silicon substrate. AZ-1512 photoresist was used for protection layer of back side and DNB-H100PL-40 photoresist was used for patterning of the front side. The mold with the thickness of $60{\mu}m$ was also formed using THB-120N photoresist and probe tip with thickness of $50{\mu}m$ was fabricated by electroplating process.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2006년도 추계학술발표회 초록집
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• pp.95-95
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• 2006

• Nuclear Engineering and Technology
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• 제51권8호
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• pp.1978-1982
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• 2019

The paper presents the electrical performance measurements of a prototype nuclear battery and two types of betavoltaic cells. The electrical performance was assessed by measuring current-voltage properties (I-V) and determining the short-circuit current and the open-circuit voltage. With ⁶³Ni as an irradiation source, the open-circuit voltage and the short-circuit current were determined as 1 V and 64 nA, respectively. The prototype consisted of 10 betavoltaic cells that were prepared using radioactive ⁶³Ni. Electroplating of the radioactive ⁶³Ni on an ohmic contact (Ti-Ni) was carried out at a current density of 20 mA/㎠. Two types of betavoltaic cells were studied: with an external ⁶³Ni source and a ⁶³Ni-covered source. Under irradiation of the ⁶³Ni source with an activity of 10 mCi, the open-circuit voltage V_oc of the fabricated cells reached 151 mV and 109 mV; the short-circuit current density J_sc was measured to be 72.9 nA/cm2 and 64.6 nA/㎠, respectively. The betavoltaic cells had the fill factor of 55% and 50%, respectively.