• 한국표면공학회지
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• 제54권4호
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• pp.171-177
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• 2021

This paper is concerned with the surface hardness measurement of NiP-coated AA7050 using different loads from 10 to 100 g. The surface hardness was observed to increase from 180 to 600 H_v with increasing NiP layer thickness, depending on the load applied for indentation. When NiP coating thickness is thinner than 2 ㎛, the surface hardness of NiP-coated AA7050 was mainly determined by AA7050 substrate, while it was significantly increased by NiP coating layer when NiP coating thickness is thicker than 2 ㎛. Hardness of AA7050 substrate itself was not dependent on the applied load but the hardness of NiP-coated AA7050 was largely influenced by the load applied for indentation. The largest difference of hardness between 10 g and 100g of applied loads, was obtained at the NiP thickness of about 8 ㎛ above which the measured hardness at 10 g reached a maximum value of about 600 H_v. It was also observed that indentation-induced plastic deformation next to the indented zone occurs when NiP layer is 5.64 times thicker than the depth of impression formed by indentation.

• 마이크로전자및패키징학회지
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• 제21권3호
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• pp.43-50
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• 2014

전자 제품의 경박 단소화 및 고집적화가 이루어 지면서 실리콘 집과 인쇄회로기판의 인터커넥션의 고신뢰도가 요구되고 있다. 본 연구는 Sn-4.0wt%Ag-0.5wt%Cu (SAC405) 솔더와 다양한 무전해 Ni-P 도금 두께에서의 high speed shear 에너지 및 파괴 모드를 연구하였다. 파괴 모드 분석을 위하여 집속이온빔(FIB) 분석이 이용되었다. 질산 기상 처리하지 않은 $1{\mu}m$ Ni-P 시편에서 낮은 shear 에너지가 나왔으며, 이는 솔더레지스트 선단에서 파단의 원인을 제공하는 것이 확인되었다. 질산 기상 처리한 시편에서 무전해 Ni-P 도금 두께가 커질수록 취성 파괴 모드는 감소한다. 또 Ni-P 도금 두께와 표면 거칠기(Ra)는 반비례 관계를 가진다. 이는 Ni-P 도금의 표면 거칠기를 낮추면 SAC405 솔더 조인트의 신뢰도를 향상시킨다는 사실을 나타낸다.

• 한국표면공학회지
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• 제51권4호
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• pp.197-201
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• 2018

Dynamic nano-indentation method was applied to characterize thin electroformed Ni-P layers. The Ni-P layers were produced in a sulphamic acid bath at $50^{\circ}C$ in $0.02A/cm^2$ for 10-60 minutes. The chemical analyses by XRD and EDX showed that the Ni-P layers were very fine grains with mainly $Ni_3P$ with Ni. The surface roughness determined by atomic force microscopy increased with thickness, which was relative to the surface morphology. The nano-hardness and the stiffness of the thin Ni-P layers with thickness of 1.9, 6.2 and $7.5{\mu}m$ were 5.52, 6.52 and 6.77 [GPa] and 56.7, 76.2 and 108.0 [${\mu}N/nm$], respectively. The elastic modulus of the Ni-P layer increased with thickness such as 37.29, 54.50 and 78.76 [GPa], respectively. The surface roughness of the electroplated Ni-P layers with diverse thickness was 8.66, 18.56 and 35.22 [nm], respectively. The enhanced nano-mechanical properties were related to mainly residual stress of the Ni-P layers.

• Journal of Welding and Joining
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• 제32권3호
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• pp.60-67
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• 2014

The ability of electronic packages and assemblies to resist solder joint failure is becoming a growing concern. This paper reports on a study of high speed shear energy of Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder with different electroless Ni-P thickness, with $HNO_3$ vapor's status, and with various pre-conditions. A high speed shear testing of solder joints was conducted to find a relationship between the thickness of Ni-P deposit and the brittle fracture in electroless Ni-P deposit/SAC405 solder interconnection. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the fractured pad surface with and without $HNO_3$ vapor treatment. A scanning electron microscopy (SEM) and an energy dispersive x-ray analysis (EDS) confirmed that there were three intermetallic compound (IMC) layers at the SAC405 solder joint interface: $(Ni,Cu)_3Sn_4$ layer, $(Ni,Cu)_2SnP$ layer, and $(Ni,Sn)_3P$ layer. The high speed shear energy of SAC405 solder joint with $3{\mu}m$ Ni-P deposit was found to be lower in pre-condition level#2, compared to that of $6{\mu}m$ Ni-P deposit. Results of focused ion beam and energy dispersive x-ray analysis of the fractured pad surfaces support the suggestion that the brittle fracture of $3{\mu}m$ Ni-P deposit is the result of Ni corrosion in the pre-condition level#2 and the $HNO_3$ vapor treatment.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.10-10
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• 2001

In this paper, initial depositing process of electroless Ni-Cu-P alloy was investigated by means of SEM, TEM and AES. The results show that the initial deposition is inhomogeneous and there exist different transition layers between different coatings and substrates, which are decided by the structures and compositions of the bath. For Ni-P binary alloy, its deposition takes place superiorly at grain boundary and on some grains with beneficial texture, the thickness of transition layer composed of Ni-Fe-P reaches 2000 angstrom. But during initiation of Ni-Cu-P trinary alloy, only at grain boundary is prIor to be deposited electrolessly, transited layer contains Ni-Fe-Cu-P and is decreased to about 500 angstrom. The structures of the films of Ni-P and Ni-Cu-P are crystalline at the initial depositing stage. The mechanisms of the process are put forward in this paper.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.157-158
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• 2013

Organic solar cell was fabricated using one-pot deposition of a mixture of NiO nanoparticles, P3HT and PCBM. In the presence of NiO, the photovoltaic performance was slightly increased comparing to that of the device without NiO. When $TiO_2$ thin films with a thickness of 2~3 nm was prepared on NiO nanoparticles using atomic layer deposition, the power conversion efficiency was increased by a factor 2.5 with respect to that with bare NiO. Moreover, breakdown voltage of the film consisting of NiO, P3HT, and PCBM on indium tin oxide was increased by more than 1 V in the presence of $TiO_2$-shell on NiO nanoparticles. It is evidenced that S atoms of P3HT can be oxidized on NiO surfaces, and $TiO_2$-shell on NiO nanoparticles. It is evidenced that S atoms of P3HT can be oxidzed on NiO surfaces, and $TiO_2$ shell heavily reduced oxidation of S at oxide/P3HT interfaces. Oxidized S atoms can most likely act as carrier generation sites and recombination centers within the depletion region, decreasing breakdown voltage and performance of organic solar cells. Our result shows that fabrication of various core-shell nanostruecutres of oxides by atomic layer deposition with controlled film thickness can be of potential importance for fabricating highly efficient organic solar cells.

• 한국진공학회지
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• 제6권S1호
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• pp.70-74
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• 1997

The study of the thickness dependence of the electron energy structure of Fe, Ni, Ti and Zr sublayers in Ni/Ti and Fe/Zr multilayers by using the experimental and computer simulated optical spectroscopy has been performed. A series of Ni/Ti and Fe/Ze multiayered films (MLF) with a bilayer period of 0.5 - 30 nm and constant (Ni/Ti) / different (Fe/Zr) sublayer thickness ratios were prepared by using computer-controlled double-pair target face-to-face sputtering onto a glass substrate at room temperature (RT) Computer simulation of the resulting optical properties of these MLF was carried out by solving of multireflection problem with a matrix method assuming either "sharp" interfaces resulting in rectangular depth profiles of the components or "mixed" (alloy-like) interfaces of variable thickness between pure-metal sublayers. Optical constants of pure bulk metals as well as equiatomic alloy interfaces were employed in these simulations. It was shown that the difference between experimental and simulated optical properties of the investigated MLF increases with decrease in sublayer thickness. This result allows to conclude that the electronic structures of sublayers below 4-5 nm thickness in mlf differ from the corresponding bulk metals.ponding bulk metals.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.75-87
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• 2001

Three different kinds of substrate used in this study : bare Cu substrate, Ni-P/Cu substrate with a Ni-P layer thickness of $5\mu\textrm{m},$ and Au/Ni-P/Cu substrate with the Ni-P and Au layers of $0.15\mu\textrm{m}$ and $5\mu\textrm{m}$ thickness respectively. The wettability of various Sn-base solders was affected by the substrate metal finish used, i.e., nickel, gold and copper. On the Au/Ni-F/Cu substrate, Sn-base solders wet better than any of the other substrate metal finishes tested. The interfacial reaction between various substrate and Sn-base solder was investigated at $70^{\circ}C,$ $100^{\circ}C,$ $120^{\circ}C,$ $150^{\circ}C,$ $170^{\circ}C$ and $200^{\circ}C$ for reaction times ranging from 0 day to 60 day. Intermetallic phases was formed along a Sn-base solder/ various substrate interface during solid-state aging. The apparent activation energy for growth of Sn-Ag/Cu, Sn-Ag-Bi/Cu, and Sn-Bi/Cu couples were 65.4, 88.6, and 127.9 Kj/mol, respectively. After isothermal aging, the fracture surface shoved various characteristics depending on aging temperature and time, and the types of BGA pad.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 춘계학술발표회 초록집
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• pp.80-81
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• 2003

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.47-51
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• 2008

In this paper, thermal stability of Nickel silicide formed on p-type silicon wafer using Ni-V alloy film was studied. As compared with pure Ni, Ni-V shows better thermal stability. The addition of Vanadium suppresses the phase transition of NiSi to $NiSi_2$ effectively. Ni-V single structure shows the best thermal stability compared with the other Ni-silicide using TiN and Co/TiN capping layers. To enhance the thermal stability up to $650^{\circ}C$ and find out the optimal thickness of Ni silicide, different thickness of Ni-V was also investigated in this work.