• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1600-1604
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• 2017

Mo-Cu alloys have been widely used for heat sink materials, vacuum technology, automobile and many other applications due to their excellent physical and electronic properties. Especially, Mo-Cu composites with 5~20 wt% copper are widely used for the heavy duty service contacts due to their excellent properties like low coefficient of thermal expansion, wear resistance, high temperature strength and prominent electrical and thermal conductivity. In most of the applications, high dense Mo-Cu materials with homogeneous microstructure are required for high performance, which has led in turn to attempts to prepare ultra-fine and well-dispersed Mo-Cu powders in different ways, such as spray drying and reduction process, electroless plating technique, mechanical alloying process and gelatification-reduction process. However, most of these methods were accomplished at high temperature (typically degree), resulting in undesirable growth of large Cu phases; furthermore, these methods usually require complicated experimental facilities and procedure. In this study, Mo-Cu alloying were prepared by planetary ball milling (PBM) and spark plasma sintering (SPS) and the effect of Cu with contents of 5~20 wt% on the microstructure and properties of Mo-Cu alloy has been investigated.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.3
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• pp.63-71
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• 2022

In this study, the interfacial reaction and drop impact reliability of Sn-Ag-Cu (SAC) solder and electroless nickel autocatalytic gold (ENAG) were studied. In addition, the solder joint properties with the ENAG surface finish was compared with electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG). The IMC thickness of SAC/ENAG and SAC/ENEPIG were 1.15 and 1.12 ㎛, respectively, which were similar each other. The IMC thickness of the SAC/ENIG was 2.99 ㎛, which was about two times higher than that of SAC/ENAG. Moreover, it was found that the IMC thickness of the solder joint was affected by the metal turnover (MTO) condition of the electroless Ni(P) plating solution, and it was found that the IMC thickness increased when the MTO increased from 0 to 3. The shear strength of SAC/ENEPIG was the highest, followed by SAC/ENAG and SAC/ENIG. It was found that when the MTO increased, the shear strength was lowered. In terms of brittle fracture, SAC/ENEPIG was the lowest among the three joints, followed by SAC/ENAG and SAC/ENIG. Likewise, it was found that as MTO increased, brittle fracture increased. In the drop impact test, it was confirmed that the 0 MTO condition had a higher average number of failures than the 3 MTO condition, and the average number of failures was also higher in the order of SAC/ENEIG, SAC/ENAG, and SAC/ENIG. As a result of observing the fracture surface after the drop impact, it was found that the fracture was between the IMC and the Ni(P) layer.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.433.2-433.2
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• 2014

그래핀(graphene)은 탄소나노튜브(CNTs)에 비해 가격 경쟁력이 있고 우수한 광투과성과 전기 및 열 전도성을 갖고 있어 반도체 소재, 방열 소재, 접점 소재 등에 적용 가능성이 높은 재료로 주목받고 있다. 특히 모바일 디바이스의 소형화, 고집적화 등의 이슈로 인해 그래핀 소재의 방열 소재 적용을 위해 다양한 연구가 진행되고 있다. 한편 산화 구리 나노선(CuO Nanowire)은 전기 및 열전도도가 우수하고 1차원 나노 구조는 부피대비 큰 표면적, 종횡비가 커서 뛰어난 열전도 구조로서 방열 소재로 응용되기 좋은 조건을 갖고 있다. 본 연구에서는 2차원 구조의 그래핀 나노플레이트(Graphene Nanoplatelet)와 1차원 구조의 CuO NW를 하이브리드화를 통해 열전도도 향상를 개선시키고자 하였다. 소재 합성은 GNP에 Cu 무전해 도금을 진행한 후 열산화 방식을 적용하여 CuO NW를 직접 성장시키는 방식으로 진행하였다. 합성된 GNP-CuONWs 다차원 나노구조체의 열전도도 측정은 에폭시에 분산시켜 레이져 플레쉬법을 이용하였다. 미세 구조 관찰 결과, CuO NW 성장 거동은 열처리 온도 및 시간 그리고 O2 가스의 순환 환경이 주요인자로 작용하는 것을 확인하였다. 열전도도 향상은 다차원 구조의 특성으로 인해 면접촉과 선접촉이 동시에 이루어졌기 때문인 것으로 분석되었으며, 이러한 CuO NWs morphology와 열전도도 향상과의 상관 관계에 대해 논의할 것이다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.145-149
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• 1995

The metallization is the key to determining cell costs, call performance, and cell and system reliabiltiy. The Burled Contact Solar Cell (BCSC) was specifical1y desinged to be compatible tilth low cost, mass production techniques and avoid the conventional metallization problem. By using electroless plating trchniqeu, we performed this metallization inexpensively and reliabley, This paper presents the details of the optimization procedure of metallization schemes on laser grooved cell surface Commercially available Ni ,Cu, and Ag plating solutions were applied for the cell metallization. The application of those solutions on the buried contact front metalization has resulted in an cell efficiency of 18.5% The cell parameters are an open circuit voltage of 651 mV, short circuit current density of 38.6 mA/$\textrm{cm}^2$, and fill factor of 73.5%.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.162-162
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• 2015

본 연구는 환경 및 인체에 유해한 포르말린을 사용하지 않은 무전해 동 도금액을 개발한 후 도금액을 전자파 차폐 섬유도금에 적용하기 위해 도금 조건에 따른 특성을 파악하였다. 본 연구에서는 무전해 동 도금액의 온도, pH, Bath loading, 도금시간을 변화시켜 도금액의 도금속도 및 도금피막의 형상을 관찰하였으며, 전자파 차폐를 위한 섬유에 개발된 도금액을 적용하고자 현재 상용 전처리 공정을 통해 도금실험을 수행하였다. 여러 도금조건을 변화하여 실험한 결과 $50^{\circ}C$의 도금액 온도, 12.8~13.5의 pH 조건에서 현재 사용 중인 포르말린 도금액과 유사하거나 더 우수한 도금속도를 나타내었으며 현재 사용중인 도금액의 대체가 가능할 것으로 판단되었다.

• Journal of Electrochemical Science and Technology
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• v.7 no.2
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• pp.132-138
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• 2016

In this study, we report the fabrication of functional complex fibers, which have been studied widely globally for numerous applications. Here, we fabricated conductive complex fibers with antibacterial properties by coating metal ions on the surface of plastic (polypropylene) fibers using the electroless and electrochemical deposition. First, we polished the polypropylene melt-blown fiber surface and obtained an absorbing Pd seed layer on its surface. Subsequently, we substituted the Pd with Cu. Bis-3-sulfopropyl-disulfide disodium salt (SPS), polyethylene glycol (PEG), and ethylene thiourea (ETU) were used as the brightener, carrier, and leveler, respectively for the electroplating. We focused on most achieving the stable plating condition to remove dendrites, which are normally during electroplating metals so that smooth layer is formed on the fiber surface. The higher the amount of SPS, the higher was the extent of irregular plate-like growth. Many irregularities in the form of round spheres were observed with increase in the amount of PEG and ETU. Hence, when the additives were used separately, a uniform coating could not be obtained. A stable coating was obtained when the three additives were combined and a uniform 5-9 μm thick copper layer with a stable morphology could be obtained around the fiber. We believe that our results can be applied widely to obtain conductive fibers with antibacterial properties and are useful in aiding research on conductive lightweight composite fibers for application in information technology and robotics.

• Journal of the Korean institute of surface engineering
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• v.49 no.6
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• pp.530-538
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• 2016

There is a close relationship between the performance and the heat generation of the electronic device. Heat generation causes a significant degradation of the durability and/or efficiency of the device. It is necessary to have an effective method to release the generated heat. Based on demands of the printed circuit board (PCB) manufacturing, it is necessary to develop a robust and reliable plating technique for substrates with high thermal conductivity, such as alumina ($Al_2O_3$), aluminium nitride (AlN), and silicon nitride ($Si_3N_4$). In this study, the plating of metal layers on an insulating silicon nitride ($Si_3N_4$) ceramic substrate was developed. We formed a Pd-$TiO_2$ adhesion layer and used APTES(3-Aminopropyltriethoxysilane) to form OH groups on the surface and adhere the metal layer on the insulating $Si_3N_4$ substrate. We used an electroless Ni plating without sensitization/activation process, as Pd particles were nucleated on the $TiO_2$ layer. The electrical resistivity of Ni and Cu layers is $7.27{\times}10^{-5}$ and $1.32{\times}10^{-6}ohm-cm$ by 4 point prober, respectively. The adhesion strength is 2.506 N by scratch test.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.88-97
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• 1996

The metallization is the key to determining cell costs, cell performance, and system reliability. Screen printing technology suffers from several limitations affecting mainly the front grid. The buried contact solar cell (BCSC) was specifically desinged to be compatible with low cost, mass production techniques and avoid the conventional metallization problem. By using electroless plating technique, we performed this metallization inexpensively and reliably. This paper presents the details of the optimization procedure of metallization schemes on laser grooved cell surfaces. Commercially available Ni, Cu and Ag plating solutions were applied for the cell metallization. The application of those solutions on the buried contact front metallization has resulted in an cell efficiency of 18.8%. The cell parameters are an open circuit voltage of 651 mV, short circuit current density of 37.1 mA/$\textrm{cm}^2$, and fill factor of 77.8 %. The efficiency of over 18 % was achieved in the above 90% of the batch.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.25-27
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• 2005

Sn-9Zn solder balls were bonded to Cu and ENIG (Electroless Nickel/Immersion Gold) pads, and the effect of aging on their joint reliability was investigated. The interfacial products were different from the general reaction layer formed in a Sn-base solder. The intermetallic compounds formed in the solder/Cu joint were $Cu_{5}Zn_{8}$ and $Cu_{6}Sn_{5}$. After aging treatment, voids formed irregularly at the bottom side of the solder because of Sn diffusion into the $Cu_{5}Zn_{8}$ IMC. In the case of the solder/ENIG joint, $AuZn_{3}$ IMCs were formed at the interface. In the case of the Sn-9Zn/ENIG, the shear strength remained nearly constant in spite of aging for 1000 hours at $150^{\circ}C$. On the other hand, in the case of the Sn-9Zn/Cu, the shear strength significantly decreased after aging at $150^{\circ}C$ for 100hours and then remained constant by further prolonged aging. Therefore, the protective plating layer such as ENIG must be used to ensure the mechanical reliability of the Sn-9Zn/Cu joint.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.1 s.34
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• pp.41-46
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• 2005

A systematic investigation of shear testing was conducted to find a relationship between Ni-Sn intermetallic spatting and the brittle fracture observed in electroless Ni(P)/solder interconnection. Brittle fracture was found in the solder joints made of Sn-3.5Ag, while only ductile fracture was observed in a Cu-containing solder (Sn-3.0Ag-0.5Cu). For Sn-3.0Ag-0.5Cu joints, $(Ni,Cu)_3Sn_4$ and/or $(Cu,Ni)_6Sn_5$ compound were formed at the interface without spatting from the Ni(P) film. For Sn-3.5Ag, $Ni_3Sn_4$ compound was formed and brittle fracture occurred in solder pads where $Ni_3Sn_4$ had spalled. From the analysis of fractured surfaces, it was found that the brittle fracture occurs through the $Ni_3SnP$ layer formed between $Ni_3Sn_4$ intermetallic layer and the Ni(P) film. Since the $Ni_3SnP$ layer is getting thicker during/ after $Ni_3Sn_4$ spatting, suppression of $Ni_3Sn_4$ spatting is crucial to ensure the reliability of Ni(P)/solder system.