• 한국표면공학회지
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• 제35권1호
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• pp.47-52
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• 2002

Intermetallic compound on the soldered interface plays important role on the bondability and mechanical properties of soldered joint. The formation of intermetallic compounds are influenced by many factors such as temperature, holding time, base metals and so on. On this study the effect of number of reflow times on the intermetallic growth was investigated. For the experimental materials, Sn-3.5Ag-0.7Cu solder ball of 0.3mm diameter and RMA-type flux were used. Thickness of intermetallic compound of solder ball by 2nd reflow showed nearly 60% higher than that of 1st reflow, and shear strength showed 10% higher value. Thickness and shear strength according to the position of interface such as upper side or lower side between two substrates were also investigated.

• 한국자기학회지
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• 제4권4호
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• pp.307-312
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• 1994

(Fe, Co)/(Pd, Pt, Cu, Ag)로 이루어진 금속 다층박막에 대한 자기광학 Kerr 효과(${\theta}_{k}$) 스펙트럼을 박막내에서 빛의 다중간섭 이론을 적용하여 계산하였고, 그 결과를 보고된 실험값과 비교하였다. Co/Pd 다층막의 경우, ${\theta}_{k}$ 스펙트럼의 조성에 따른 파장 의존성에 대한 계산값이 서로 잘 일치하였으며, Fe/Cu 및 Fe/Ag 다층막에 있어서는 Cu와 Ag의 광흡수단 영역에서 다층막 고유의 새로운 peak가 나타나는 실험현상을 계산결과로 설명이 가능하였다. 그러나 Co/Pt 다층막의 경우에는 실험으로 측정된 300 nm파장 영역에서의 거대한 자기 광학 효과를 다중간섭이론으로는 설명할 수 없었으며, 이는 Co 또는 Pt 고유의 광학정수가 다층막을 이루면서 변화되어 나타나는 현상으로 생각된다.

• 한국정보통신학회논문지
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• 제13권1호
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• pp.110-114
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• 2009

최근에 유기물 전계효과 트랜지스터의 연구는 전자소자분야에서 널리 알려져 있다. 특히 본 연구에서는CuPc 물질을 기본으로 하여 소자를 제작하고, 또한 기판의 온도를 달리 하여 제작하였다. CuPc FET 소자는 top-contact 방식으로 제작하였으며, 기판의 온도는 상온과 $150^{\circ}C$로 달리 하였다. 또한 CuPc의 두께는 40nm로 하였고, 채널의 길이는 $50{\mu}m$, 폭은 3mm로 하였다. 제작된 소자를 이용하여 전압-전류 특성을 측정하였다.

• 대한금속재료학회지
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• 제46권5호
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• pp.283-288
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• 2008

We observed the in-situ stress behavior of Cu and Ag thin films during deposition using a thermal evaporation method. Multi-beam curvature measurement system was used to monitor the evolution of in-situ stress in Cu and Ag thin films on 100 Si(100) substrates. The measured curvature was converted to film stress using Stoney formula. To investigate the effects of the deposition rates on the stress evolution in Cu and Ag thin films, Cu and Ag films were deposited at rates ranging from 0.1 to $3.0{\AA}/s$ for Cu and from 0.5 to $4.0{\AA}/s$ for Ag. Both Cu and Ag films showed a unique three stress stages, such as 'initial compressive', 'a tensile maximum' and followed by 'incremental compressive' stress. For both Cu and Ag films, there is no remarkable effect of deposition rate on the thickness and average stress at the tensile maximum. There is, however, a definite decrease in the incremental compressive stress with increasing deposition rate.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.253-254
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• 2006

We have manufactured CdS and Cd(Cu)S thin films by chemical bath deposition(CBD) process, and examined the effects of $NH_4Cl$ and TEA. The addition of $NH_4Cl$ remarkably enhanced the film thickness of CdS, however, TEA slightly decreased the film thickness. The thickness of CdS film prepared from the aqueous solution of 0.003 M $CdSO_4$ 0.00008 M $CuSO_4$, 1.3M NH3, 0.03 M $SC(NH_2)_2$ and 0.0009 M $NH_4Cl$ was 210 nm and resistivity of that was $1.2{\times}10^3{\Omega}cm$.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.49-53
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• 2002

The Sn-Cu eutectic solder bump formation ($140{\mu}{\textrm}{m}$ diameter, $250{\mu}{\textrm}{m}$ pitch) by electroplating was studied for flip chip package fabrication. The effect of current density and plating time on Sn-Cu deposit was investigated. The morphology and composition of plated solder surface was examined by scanning electron microscopy. The plating thickness increased with increasing time. The plating rate increased generally according to current density. After the characteristics of Sn-Cu plating were investigated, Sn-Cu solder bumps were fabricated on optimal condition of 5A/dm$^2$, 2hrs. Ball shear test after reflow was performed to measure adhesion strength between solder bump and UBM (Under Bump Metallization). The shear strength of Sn-Cu bump after reflow was higher than that of before reflow.

• 한국표면공학회지
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• 제39권6호
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• pp.255-262
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• 2006

Pd-Cu alloy membrane for hydrogen separation was fabricated by sputtering and Cu reflow process. At first, the Pd and Cu was continuously deposited by sputtering method on oxidized Si support, the Cu reflow process was followed. Microstructure of the surface and permeability of the membrane was investigated depending on various reflow temperature, time, Pd/cu composition and supports. With respect to our result, Pd-Cu thin film (90 wt.% Pd/10 wt.% Cu) deposited by sputtering process with thickness of $2{\mu}m$ was heat-treated for Cu reflow The voids of the membrane surface were completely filled and the dense crystal surface was formed by Cu reflow behavior at $700^{\circ}C$ for 1 hour. Cu reflow process, which is adopted for our work, could be applied to fabrication of dense Pd-alloy membrane for hydrogen separation regardless of supports. Ceramic or metal support could be easily used for the membrane fabricated by reflow process. The Cu reflow process must result in void-free surface and dense crystalline of Pd-alloy membrane, which is responsible for improved selectivity oi the membrane.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1537-1540
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• 2003

MEMS technology with micro scale is complete system utilized as the sensor. micro electro device. The metallization of MEMS is very important to transfer the power operating the sensor and signal induced from sensor part. But in the MEMS structures local stress concentration and deformation is often happened by geometrical shape and different constraint on the metallization. Therefore. this paper studies the effect of supporting type and thickness ratio about thin film thickness of the substrate thickness for the residual stress variation caused by thermal load in the multi-layer thin film. Specimens were made from materials such as Al, Au and Cu and uniform thermal load was applied, repeatedly. The residual stress was measured by FEA and nano-indentation using AFM. Generally, the specimen made of Al induced the large residual stress and the 1st layer made of Al reduced the residual stress about half percent than 2nd layer. Specimen made of Cu and Au being the lower thermal expansion coefficient induce the minimum residual stress. Similarly the lowest indentation length was measured in the Au_Cu specimen by nano-indentation.

• 한국생산제조학회지
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• 제20권5호
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• pp.559-563
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• 2011

Drop impact reliability assessment of solder joints on the flip chip is one of the critical issues for micro system packaging. Our previous researches have been showing that new solder ball compositions of Sn-3.0Ag-0.5Cu has better mechanical reliability than Sn-1.0Ag-0.5Cu. In this paper, dynamic reliability analysis using Finite Element Analysis (FEA) is carried out to assess the factors affecting flip chip in drop simulation. The design parameters are size and thickness of chip, and size, pitch and array of solder ball with composition of Sn1.0Ag0.5Cu. The board systems by JEDEC standard including 15 chips, solder balls and PCB are modeled with various design parameter combinations, and through these simulations, maximum yield stress and strain at each chip are shown at the solder balls. It is found that larger chip size, smaller chip array, smaller ball diameter, larger pitch, and larger chip thickness have bad effect on maximum yield stress and strain at solder ball of each chip.

• 한국표면공학회지
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• 제50권4호
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• pp.244-250
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• 2017

Effects of plating conditions (dispersant concentration, plating time, and ultrasonication) on electroless Cu plating on SiC fabric woven by crossing of SiC continuous fibers vertically were studied. The ultrasonic dispersion treatment not only did not improve the dispersion of the SiC fibers, but also did not change the plating thickness. The ultrasonication in the pretreatment step of electroless plating did not improve the dispersion of the fibers, while the ultrasonication in the plating step enhanced the dispersion of the fibers and decreased the thickness of the Cu films. It was possible to control the thickness of the Cu coating layer as well as the dispersion of the fibers in the fabric by changing the plating conditions such as dispersant concentration, plating time, and ultrasonication, but it was very difficult to coat copper on the intersection of vertical fibers in the fabric.