• Journal of the Korean institute of surface engineering
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• v.24 no.2
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• pp.103-113
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• 1991

Electroless Ni-Cu-P alloy plating of Al base hard disk was performed to investigate some properties according to the change of composition. It was found that the composition of Ni and Cu in deposits changed linearly with increasing the mole ratio of NiSO4.6H2O/CuSO4.5H2O. The increase in hardness by heat - treatment was confirmed to be associated with small size grained crystallization of the amorphous deposits. Acid resistance of all deposits layer. which had been heated up to 30$0^{\circ}C$, was found to be exellent when immersed in 1N-H2SO4 solution, and it showed more superior acid resistance with decreasing Cu content and with increasing P. The resistivity of the deposits heat treated became smaller at temperature more than 50$0^{\circ}C$, and it became largerly with increasing P content. Cu 44.1wt% alloy(C bath) showed the most superior non-magnetically stable characteristics after heat treatment. It was superiorly with higher temperature and with decreasing P content.

• Journal of the Korean institute of surface engineering
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• v.27 no.4
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• pp.193-206
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• 1994

A wear behavior of electroless (Ni-P-X, X: SiC, $Al_2O_3$, Diamond) composite coating layers, formed under various conditions on commerical grade low carbon steel, has been investigated using Taber abrasion tester and scanning electron microscope. Several factors, which are type of particles, co-deposited content, particle size, distribution of particles and heat-treatment, influenced the wear resistance. The wear resistance of the composited coating layers after heat-treatment at $400^{\circ}C$ for 1 hr was increased 70 times with diamond, 15 times with SiC and 8 times with $Al_2O_3$, compared with the electroless nickel plating layer without heat-treatment.

• Korean Journal of Materials Research
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• v.10 no.12
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• pp.853-863
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• 2000

In this study, a new UBM materials system for solder flip chip interconnection of Cu pads were investigated using electroless copper (E-Cu) and electroless nickel (E-Ni) plating method. The interfacial reaction between several UBM structures and Sn-36Pb-2Ag solder and its effect on solder bump joint mechanical reliability were investigated to optimife the UBM materials design for solder bump on Cu pads. Fer the E-Cu UBM, continuous coarse scallop-like $Cu_{6}$ $Sn_{5}$ , intermetallic compound (IMC) was formed at the solder/E-Cu interface, and bump fracture occurred this interface under relative small load. In contrast, Fer the E-Ni/E-Cu UBM, it was observed that E-Ni effectively limited the growth of IMC at the interface, and the Polygonal $Ni_3$$Sn_4$ IMC was formed because of crystallographic mismatch between monoclinic $Ni_3$$Sn_4$ and amorphous E-Ni phase. Consequently, relatively higher bump adhesion strength was observed at E-Ni/E-Cu UBM than E-Cu UBM. As a result, it was fecund that E-Ni/E-Cu UBM material system was a better choice for solder flip chip interconnection on CU PadS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.95-101
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• 2017

In this paper, the sizing removal condition for the pretreatment of composite materials is obtained numerically by applying an image processing algorithm and nickel-plated carbon fiber is fabricated by a dry process method to enhance its electromagnetic shielding performance. Sizings that are wrapped in a polymer type material during the manufacturing of carbon fiber should be removed for dry coating. A numerical value, that is the correlation, can be obtained by determining the regular pattern of the carbon fiber in the image taken by a scanning electron microscope (SEM) after the sizing is removed. The application of the proposed numerical method to the SEM image of the fiber after the sizing is removed with solution, compressed air, solution and compressed air (hybrid), showed that this method of eliminating the sizing is superior to the hybrid method. Then, by spreading the carbon fiber roll with the sizing removed, we were able to produce nickel plated carbon fiber by the roll-to-roll sputtering method. The electromagnetic shielding performance of the fabricated 30, 40 and 100 nickel coated carbon fibers was measured. The Korea Advanced Institute of Science and Technology evaluated the electromagnetic shielding performance of the 100 nickel-coated carbon fiber to have a maximum value of 73.2 (dB) and a minimum value of 66.7 (dB). This is similar to the electromagnetic shielding rate of copper and shows that this material can be used as a cable for EV / HEV automobiles.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.83-88
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• 2010

The composite electroplating is accomplished by adding inert materials during the electroplating. Permalloy is the term for Ni-Fe alloy and it is used for industrial applications due to its high magnetic permeability. Microhardness for microdevices is enhanced after composite coating and it increases the life cycle. However, the hydroxyl group on the silica makes their surface susceptible to moisture and it causes the silica nanoparticles to be agglomerated in the aqueous solution. The agglomeration problem causes poor dispersion which eventually interrupts uniform deposition of silica nanoparticles. In this study, the dispersion of silica nanoparticles in the permalloy electroplated layer is reported with variation of additives and sonication time. Longer sonication period guaranteed better silica nanopowder dispersion and sonication period also influenced on composition of deposits. The amount of silica nanopowder codeposition and surface morphologies were influenced with variation of additives. In alkaline bath, smooth surface morphology and relatively high contents of silica nanopowder codeposition were obtained with addition of sodium lauryl sulfate.

• Korean Journal of Materials Research
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• v.8 no.5
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• pp.444-449
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• 1998

There are various shielding materials that have been considered; the use of a metallic plate or the layering of a conductive material on a plastic surface and the insertion of filler in plastics. All of these methods have shown their merits and weakness. Therefore, many studies have concentrated on developing materials that effectively cut down EMI without increase in weights of housing materials. In these respects, this study has focused on investigations of the shielding effect of materials that have electroless nickel plating on the lamella structured micro particles surface with low specific gravity. When a film of electroless nickel were plated on a micro particle surfaces and then mixed with paint, the electromagnetic shielding effects were measured as 63dB. Although these effects were less than that 90dB of the copper plate, trials in a series of 6 times increased the shielding effect by IOdB and is applicable to wide range of EMI shielding.

• Composites Research
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• v.21 no.2
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• pp.31-35
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• 2008

In order to design light weight and high efficient electromagnetic wave absorbing materials, hollow magnetic particles have been introduced in this study. The electroless plating method has been utilized to coat Ni and Fe on the substrates of synthesized polystyrene particles of submicron size. Removing polystyrene particles by heat treatment resulted in hollow structures. Observation by SEM, TEM and EDS confirmed the surface morphology and coating thickness of Ni and Fe. Polymeric composites containing hollow particles were tested in order to compare the electromagnetic properties between Ni coated and Fe costed particles. The composite of 30 wt% Fe hollow particles showed the higher complex permeability than Ni hollow particles or the conventional barium ferrite particles.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.73-83
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• 2022

The purpose of this paper was to identify a method to improve received noise in a specific frequency band, caused by RF radiation signals during aircraft operation. The communication equipment of the aircraft is critical to the performance and safety of the flight mission, as it is responsible for the function of internal and external communications. Noise-free, clean communication quality, as well as transmission and receiving functions have to be implemented. Thus, the cause analysis of the reception noise in a specific frequency band, was analyzed through trouble shooting. The receiving noise due to the RF radiation signal emitted from the subsystem unit inside the aircraft, was improved by shielding with a CAP with electroless nickel plating applied. Additionally, the measurement and verification results of the improvement method are also described.

• Composites Research
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• v.20 no.5
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• pp.43-48
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• 2007

The absorption and the interference shielding of electromagnetic wave have been very important issues for commercial and military purposes. The stealth technique is one of the most typical applications of electromagnetic wave absorption technology. This study has started for the development of composite fillers containing dielectric and magnetic lossy materials. To improve the electromagnetic characteristics of conductive nano fillers, carbon nanofibers (CNFs) with nickel-phosphorous (Ni-P) or nickel-iron (Ni-Fe) have been fabricated by the electroless plating process. Observations by the electron microscopy (SEM/TEM) and element analyzer (EDS/ELLS) showed the uniform Ni-P and Ni-Fe coated CNFs. The compositions of the plating layers were about Ni-6wt%P and Ni-70wt%Fe, respectively. The average thicknesses of the plating layers were about $50\;{\sim}\;100\;nm$.

• The korean journal of orthodontics
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• v.33 no.2 s.97
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• pp.121-130
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• 2003

The purpose of this study was to evaluate the possibile clinical application of electroplating to increase diameter of an orthodontic wire, through examining the change of physical properties. The diameter of stainless steel orthodontic wire was increased from 0.016 inch to 0.018 inch by electroplating in a bath of nickel sulfate 100g/L, nickel chloride 60g/L, boric acid 30g/L, and sodium chloride 50g/L, under the conditions of 1.7V, $25\~29^{\circ}C\;and\;3.1\~3.3pH$. During the electroplating, the rate of diameter increase was measured every minute. To investigate uniformity, the diameter was measured at three different locations of each wire specimen aster electroplating. An X-ray diffraction test was performed to analyze the nature of the electroplated metal. Following heat treatment to improve adhesion between the wire and electroplated metal, a three-point bending test was conducted to compare stiffness, field strength, and ultimate strength among four wire groups; 0.016 inch, electroplated 016, electroplated and heat-treated 016, and 0.018 inch wires. Through the comparison of each wire group, following results were obtained. 1. In the load-deflection graph, the curve of the electroplated group was Placed between that of the 0.016 inch group and the 0.018 inch group, and the owe was closer to the 0.018 inch group by heat treatment. 2. In the electroplated and heat-treated 016 wire group, the values of stiffness, yield strength and ultimate strength showed higher tendency than in the original 0.016 Inch group. Stiffness and ultimate strength showed statistically significant differences between two groups. 3. Stiffness, yield strength, and ultimate strength of electroplated wire presented lower values than those of 0.018 inch wire group. 4. Stiffness, yield strength, and ultimate strength of electroplated and heat-treated wire showed higher tendency than those of electroplated wire group, and ultimate strength showed statistically significant difference between two groups. 5. After electroplating, the difference in diameter between the three locations was within $0.1\~0.3\%$ variation, and showed no statistical significance.