• Journal of Adhesion and Interface
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• v.4 no.2
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• pp.10-20
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• 2003

This paper is relative to the electroless deposition of nickel or copper films on polyimide and polytetrafluoroethylene substrates. First, it is presented an original approach of the electroless process which consists in grafting nitrogenated functionalities on the polymer surfaces via plasma or VUV-assisted treatments operating in a nitrogen-based atmosphere ($NH_3$, $N_2$), and then in catalysing the grafted surfaces in an aqueous tin-free, Pd(+2)-based solution. Adhesion of the Pd(+2) catalytic species on polymer surfaces is explained by the formation of strong covalent bonds between these species and the grafted nitrogenated groups. Second, it is show how a fragmentation test performed in conjunction with electrical measurements can be used to characterize the practical adhesion of the electroless coatings deposited on flexible polymer substrates, and to evidence the influence of some experimental parameters (plasma treatment time and nature of the gas phase).

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.7-11
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• 2003

The semiconductor chips or electronic components generate heat, which causes malfunction of the parts when it was not cooled properly. Bulky heat sink and cooling fan are used to get rid of the heat. However, with this bulky system, it is hard to integrate the electronics system in a small scale. The cooling efficiency of the system depends on the surface area of the heat sink, thermal conductivity of the material and the method of integration. In order to develop a novel cooling system, a micro-heatsink with a large surface area while retaining small volume was fabricated by electroless deposition of gold/copper inside a Track-etched membrane. The structure of the micro-heatsink was investigated using SEM or optical microscope. It was also found that the micro-heatsink is more efficient than a flat copper plate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1507-1510
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• 2005

This study was carried out as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-\mu{m}-deep$ indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.49 GPa and 100 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46-0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined area during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.171-177
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• 2006

This study was performed as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-{\mu}m$-deep indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.51 GPa and 104 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$ ) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46- 0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined are a during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• Korean Journal of Materials Research
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• v.14 no.8
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• pp.552-557
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• 2004

Thin Ni-B films, 1 ${\mu}m$ thick, were electrolessly deposited on Cu bus electrode fabricated by electro deposition. The purpose of these films is to encapsulate Cu electrodes for preventing Cu oxidation and to serve as a diffusion barrier against copper contamination of dielectric layer in AC-plasma display panel. The layers were heat treated at $580^{\circ}C$(baking temperature of dielectric layer) with and without pre-annealing at $300^{\circ}C$($Ni_{3}B$ formation temperature) for 30 minutes. In the layer with pre-annealing, amount of Cu diffusion was lower about 5 times than that in the layer without pre-annealing. The difference of Cu concentration could be attributed to Cu diffusion before $Ni_{3}B$ formation at grain boundaries. However, the diffusion behavior of the layer with pre-annealing was similar to that of the layer without pre-annealing after $Ni_{3}B$ formation. With increasing annealing time, Cu concentration of both layers increased due to grain growth.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.714-719
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• 1996

For the fabrication of the circuits, contact or terminal areas are usually coated with nickel and gold. Usually, diluted palladium solution is applied to initiate electroless nickel plating on the copper circuits. However, the trace amounts of palladium remains on the resin and it causes the extraneous deposition. We confirmed that selectivity was greatly improved by the treatment with the strong reducing agents such as SBH or DMAB. Bondability was greatly influenced by the contents of phosphorus in the deposited nickel. Stabilizers in the electroless gold plating were also influenced the bonding strength. The baths containing cupferron or potassium nickel cyanide as a stabilizer showed superior bondability. The gold deposits having strong orientation with Au(220) and Au(311) showed good bond ability.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.250-253
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• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. The Ni contact was formed on the front grid pattern by electroless plating followed by anneal ing at $380{\sim}400^{\circ}C$ for $15{\sim}30$ min at $N_{2}$ gas to allow formation of a nickel-silicide in a tube furnace or a rapid thermal processing(RTP) chamber because nickel is transformed to NiSi at $380{\sim}400^{\circ}C$. The Ni plating solution is composed of a mixture of $NiCl_{2}$ as a main nickel source. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. The Ni/Cu contact was found to be well suited for high-efficiency solar cells and was successfully formed by using electroless plating and electroplating, which are more cost effective than vacuum evaporation. In this paper, we investigated low-cost Ni/Cu contact formation by electroless and electroplating for crystalline silicon solar cells.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.217-221
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• 2015

Developing a metallization that has low cost and high efficiency is essential in solar-cell industries, to replace expensive silver-based metallization. Ni/Cu two-step metallization is one way to reduce the cost of solar cells, because the price of copper is about 100 times less than that of silver. Alkaline electroless plating was used for depositing nickel seed layers on the front electrode area. Prior to the nickel deposition process, 2% HF solution was used to remove native oxide, which disturbs uniform nickel plating. In the subsequent step, a nickel sintering process was carried out in $N_2$ gas atmosphere; however, copper was plated by light-induced plating (LIP). Plated nickel has different properties under different bath conditions because nickel electroless plating is a completely chemical process. In this paper, plating bath conditions such as pH and temperature were varied, and the metal layer's structure was analyzed to investigate the adhesion of Ni/Cu metallization. Average adhesion values in the range of 0.2-0.49 N/mm were achieved for samples with no nickel sintering process.

• Resources Recycling
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• v.10 no.2
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• pp.27-33
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• 2001

Reusing of electroless Ni-Cu-P waste solution was investigated in the plating time, plating rate, solution composion and deposit. Plating time of nickel-catalytic surface took longer than that of zincated-catalytic surface. Initial solution with 50f) waste solution additive at batch type was possible to reusing of waste solution. Plating time of initial solution at continuous type took longer 10 times over than that of batch type. Plating time of 50% waste solution additive at continuous type took longer 3.7 times over than that of batch type. Component change of nickel-copper for electroless deposition was greatly affected by depolited inferiority and larger decreased plating rate.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.11-16
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• 2004

Electronic devices are getting smaller due to integration of electronic chip, and heat generated in electronic devices can cause loss of performance and/or reliability of the devices. In this research, metals such as gold, nickel and copper are plated onto a porous membrane by electroless plating method to make an efficient micro-heatsinks. Electroless plating includes sensitization and activation steps in pre-treatment steps. A polycarbonate(PC) membrane was sensitizied, activated and deposited in each metal solution for plating. Among manufactured microfibrils, heat transfer and radiation properties of Ni-microfibril with high surface area were more effective than those of $Au^-$ and Cu-microfibril.