• Journal of Welding and Joining
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• 제33권3호
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• pp.47-53
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• 2015

By the trends of electronic package to be more integrative, the fine Cu trace pitch of organic PCB is required to be a robust design. In this study, the short circuit failure mechanism of PCB with a Cl element under the Temperature humidity bias test ($85^{\circ}C$/85%RH/3.5V) was examined by micro-structural study. A focused ion beam (FIB) and an electron probe micro analysis (EPMA) were used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $CuCl_x$ were formed and grown on Cu trace during the $170^{\circ}C$/3hrs and that $CuCl_x$ was decomposed into Cu dendrite and $Cl_2$ gas during the $85^{\circ}C$/85%RH/3.5V. It is suggested that Cu dendrites formed on Cu trace lead to a short circuit failure between a pair of Cu traces.

• Tribology and Lubricants
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• 제23권2호
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• pp.66-72
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• 2007

[ $MoS_2$ ], is a well-known metal sulfide applied as solid lubricants and an additive to prolong the life of sintered bearings under severe conditions. However, the high price of $MoS_2$ limited its wide application. This study is aimed to investigate the possibility far application to solid lubricants for $Cu_2S$ as a substitute of $MoS_2$. Bronzes added $Cu_2S$ and $MoS_2$, are produced by powder metallurgy in this study, and then evaluated their friction and wear properties., as well as sintered bronze. The sliding wear test using pin-on-disc type machine, was conducted at several sliding speeds for three type test pieces sintered bronzes added $Cu_2S$ and $MoS_2$, and sintered bronze without lubricants. Addition of $Cu_2S$ to bronze leads to relatively good friction properties, although it is not so good as addition of $MoS_2$. However, the wear properies of sintered bronze added $Cu_2S$ are better than that of sintered bronze added $MoS_2$.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.60-67
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• 2008

The catalytic filter of Cu-ZSM5/alumina beads was considered to reduce NOx in the urea SCR system. Catalytic support of porous alumina beads with mean pore size $130{\mu}m$ and porosity $75{\sim}83%$ were prepared using foaming and gel-casting method. The Cu-ZSM5 catalysts were coated on the supporting alumina beads using $Cu(NO_3)_2$ by ion exchange method. After a washcoating process was applied to coat 10w% Cu-ZSM5 on porous alumina bead, coating layer was estimated $20{\mu}m$ in thickness. The characterization and the feasibility as a catalytic supports were investigated. And the NOx conversion test in Cu-ZSM5/Alumina Beads filter system was conducted by using Urea as reductants under laboratory test. The NOx conversion was increased as size and porosity of beads and observed more than 95% excellent NOx conversion above $300^{\circ}C$.

• 한국표면공학회지
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• 제57권3호
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• pp.192-200
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• 2024

Cu as a heat exchanger tube is an important component in thermal fluid transfer. However, Cu tubes are exposed to stress in certain environments, leading to stress corrosion cracking (SCC). In this study, the effect of Sn addition on microstructure and corrosion characteristics was examined. The microstructural examination revealed the presence of columnar crystal and a grain refinement due to the addition of Sn. Electrochemical measurements showed that the 5 wt.% NH₃ environment was the most vulnerable environment to Cu corrosion, and the corrosion current density increased as stress increased. The immersion test exhibited the formation of Cu2O and Cu(OH)₂ corrosion product in 3.5 wt.% NaCl and 5 wt.% NH₃ environments, respectively. Results indicated that Sn addition to Cu was an important factor in improving the mechanical strength.

• Journal of Welding and Joining
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• 제20권6호
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• pp.59-59
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• 2002

Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp. : 250℃ and conveyer speed : 0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was 250℃. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn (5㎛), Cu/Ni (5㎛), and Cu/Ni/Au (5㎛/500Å) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

• Journal of Welding and Joining
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• 제20권6호
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• pp.783-788
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• 2002

Sn-Ag-Cu solder is known as most competitive in many kinds of Pb-free solders. In this study, effects of solderability with plated layers such as Cu, Cu/Sn, Cu/Ni and Cu/Ni/Au were investigated. Sn-3.5Ag-0.7Cu solder balls were reflowed in commercial reflow machine (peak temp.:$250^{\circ}C$and conveyer speed:0.6m/min). In wetting test, immersion speed was 5mm/sec., immersion time 5sec., immersion depth 4mm and temperature of solder bath was $250^{\circ}C$. Wettability of Sn-3.5Ag-0.7Cu on Cu, Cu/Sn ($5\mu\textrm{m}$), Cu/Ni ($5\mu\textrm{m}$), and Cu/Ni/Au ($5\mu\textrm{m}/500{\AA}$) layers was investigated. Cu/Ni/Au layer had the best wettability as zero cross time and equilibrium force, and the measured values were 0.93 sec and 7mN, respectively. Surface tension of Sn-3.5Ag-0.7Cu solder turmed out to be 0.52N/m. The thickness of IMC is reduced in the order of Cu, Cu/Sn, Cu/Mi and Cu/Ni/Au coated layer. Shear strength of Cu/Ni, Cu/Sn and Cu was around 560gf but Cu/Ni/Au was 370gf.

• 마이크로전자및패키징학회지
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• 제21권1호
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• pp.45-50
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• 2014

반도체 미세구리배선 적용을 위하여 구리배선의 습식 표면처리 및 열 사이클에 따른 구리 박막과 실리콘질화막 도포층 사이의 계면접착에너지를 4점굽힘시험을 통해 정량적으로 평가하였다. 구리배선을 화학적 기계적 연마한 후 습식 표면처리를 통하여 구리 박막과 실리콘질화막의 계면접착에너지는 $10.57J/m^2$에서 $14.87J/m^2$로 증가하였다. $-45{\sim}175^{\circ}C$범위에서 250사이클 후, 표면처리를 하지 않은 시편의 계면접착에너지는 $5.64J/m^2$으로, 표면처리를 한 시편은 $7.34J/m^2$으로 감소하였으며, 모든 시편의 박리계면은 구리 박막과 실리콘질화막 계면으로 확인되었다. X-선 광전자 분광법으로 계면 결합 상태를 분석한 결과, 화학적 기계적 연마 공정 후 구리배선의 표면 산화물이 습식표면처리에 의해 효과적으로 제거된 것을 확인하였다. 또한, 열 사이클 처리동안, 구리 박막과 실리콘질화막의 큰 열 팽창 계수 차이로 인한 열응력으로 인하여 구리 박막과 실리콘질화막 계면이 취약해지고, 계면을 통한 산소유입에 따른 구리 산화층이 증가하여 계면접착에너지가 저하된 것으로 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.447-452
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• 2004

Vacuum interrupters in order to be used in various switch-gear components such as circuit breakers, distribution switches, contactors, etc. spread the arc uniformly over the surface of the contacts. The electrodes of vacuum interrupters are made of sinter-forged Cu-Cr materials for good electrical and mechanical characteristics. Since the closing velocity is 1-2m/s and impact deformation of the electrode depends on the strain rate at that velocity, the dynamic behavior of the sinter-forged Cu-Cr is a key to investigate the impact characteristics of the electrodes. The dynamic response of the material at intermediate strain rate is obtained from the high speed tensile test machine test and at the high strain rate is obtained from the split Hopkinson pressure bar test. Experimental results from both quasi-static and dynamic compressive tests are interpolated to construct the Johnson-Cook model as the constitutive relation that should be applied to simulation of the dynamic behavior of the electrodes. The impact characteristics of a vacuum interrupter are investigated with computer simulations by changing the amount of chromium content.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.383-386
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• 2007

In this study, the analysis was carried out for Electrical Discharge Machining (EDM) characteristics of the Cu electrodes by LIGA process. The shape of electrodes has 324 pins for the cavity of BGA(Ball Grid Array) type test socket mold. BGA test sockets are used in the inspection process of the semi-conductor I.C chip manufacturing. In the work, the machining performance for EDM of the electrodes was analyzed on dimensional accuracy and wear rate. The dimensional accuracy was measured for dimension of the pins, pitch size between the pins and the roundness of corner edge using optical measuring machine.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.21-23
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• 2006

The microstructural investigation and thermo-mechanical reliability evaluation of the Sn-3.0Ag-0.5Cu solder bumped flip chip package were carried out during the thermal shock test of the package. In the initial reaction, the reaction product between the solder and Cu mini bump of chip side was Cu6Sn5 layer, while the two phases which were (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4 were formed between the solder and Ni-P layer of the package side. The cracks were occurred at the corner solder joints after the thermal shocks of 400 cycles. The primary failure mechanism of the solder joints in this type of package was confirmed to be thermally activated solder fatigue failure.