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Study on the Mechanical Properties and Thermal Conductive Properties of Cu/STS/Cu Clad Metal for LED/semiconductor Package Device Lead Frame (LED 및 반도체 소자 리드프레임 패키징용 Cu/STS/Cu 클래드메탈의 기계적/열전도/전기적 특성연구)

  • Lee, Chang-Hun;Kim, Ki-Chul;Kim, Young-Sung
    • Journal of Welding and Joining
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    • v.30 no.3
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    • pp.32-37
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    • 2012
  • Lead frame which has a high thermal conductivity and high mechanical strength is one of core technology for ultra-thin electronics such as LED lead frames, memory devices of semiconductors, smart phone, PDA, tablet PC, notebook PC etc. In this paper, we fabricated a Cu/STS/Cu 3-layered clad metal for lead frame packaging materials and characterized the mechanical properties and thermal conductive properties of the clad metal lead frame material. The clad metal lead frame material has a comparable thermal conductivity to typical copper alloy lead frame materials and has a reinforced mechanical tensile strength by 1.6 times to typical pure copper lead frame materials. The thermal conductivity and mechanical tensile strength of the Cu/STS/Cu clad metal are 284.35 W/m K and $52.78kg/mm^2$, respectively.

Optimization of Peltier Current Leads Cooled by Two-Stage Refrigerators

  • Jeong, Eun-Soo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.14 no.3
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    • pp.94-101
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    • 2006
  • A theoretical investigation to find thermodynamically optimum design conditions of conduction-cooled Peltier current leads is performed. A Peltier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high temperature superconductor (HTS) lead in the order of decreasing temperature. Mathematical expressions for the minimum heat flow per unit current crossing the TE-metal interface and the minimum heat flow per unit current from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE -metal interface possesses a unique optimal value that minimizes the heat flow to the joint and that this optimal value depends on the material properties of the TE and the metallic lead but not the joint temperature nor electric current. It is also shown that there exists a unique optimal value for the joint temperature between the metal and the HTS leads that minimizes the sum of the power dissipated by ohmic heating in the current leads and the refrigerator power consumed to cool the lead, for a given length of the HTS.

A Study on the Effect of Air Pollutants in Daegu Area by Biological Indicator of Roadside (道路 指標生物을 이용한 대기오염이 植物에 미치는 영향에 관한 연구)

  • Kang, Hoe-Yang;Cha, Sang-Eun;Ha, Cheong-Gun
    • Journal of Environmental Health Sciences
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    • v.14 no.2
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    • pp.29-41
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    • 1988
  • This study was performed to investigate the air pollution levels in Daegu area titrough measuring of contents of water, chlorophyll, water soluble sulfur and lead metal in the leaves of roadside trees and chemical properties of soil under the urban trees. The results can be summarized as follows 1. The range of water content was from 60.4% to 74.6%. The comparisons of chlorophyll, water soluble sulfur and water content were regression equation, chlorophyll=0.1981+ 0.0040 water content (July), water soluble sulfur=3,139-0.0416 water content (July). and correlation coefficient, r=0.561 and r=0.549 respectively 2. Average contents of chlorophyll, water soluble sulfur and lead metal in the leaves of roadside tree at sampling sites were chlorophyll 0.050, 0.072mg/cm$^2$, water soluble sulfur 0.244, 0.333%, and lead metal 12.25, 12.68ppm in Oct. and Jul. respectively. 3. Correlation between chlorophyll and contents of water soluble sulfur and lead metal in the leaves of roadside tree at sampling sites were water soluble sulfur r=-0.564, -0.613 and lead metal r=-0.693, -0.699 in October and July, respectively. 4. Correlation between chlorophyll and water content, water soluble sulfur and lead metal in the leaves of tree showed positive significance.

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Comparison of Heavy Metal Level in Blood Between Industrial Workers and General People

  • Lee Mi-Hwa
    • Biomedical Science Letters
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    • v.10 no.4
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    • pp.453-457
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    • 2004
  • The welders and car painters are frequently exposed to heavy metals such as lead, zinc, cadmium and chromium, and those are a major source of heavy metal poisoning. This study was carried out to investigate the relationship of the heavy metal level in blood by age, working duration, and smoking status among 105 industrial workers and 88 general people in Gyeongnam province from October 2003 to October 2004. The heavy metal level in blood was analyzed by atomic absorption spectrophotometer. Mean blood lead level in exposed group and control group was 8.40±4.67μl/dl, 1.82±1.35μl/dl, respectively. Mean blood zinc level in exposed group and control group was 9.43±5.38 ㎍/ml, 2.89±1.79㎍/ml, respectively. Mean blood cadmium level in Exposed group and control group was 1.53±1.05μl/dl, 0.60±0.49 μl/dl, respectively. Mean blood chromium level in exposed group and control group was 0.89±0.76μl/dl, 0.68±0.63μl/dl, respectively. Lead, zinc, cadmium and chromium level in blood of exposed group was significantly higher than that of control group. In the comparison of smoking status, lead, zinc and cadmium level of smoker's was significantly higher than that of non-smoker's. Comparison of heavy metal level by age, lead, zinc, cadmium level in 40's, 50's (exposed group) in blood significantly higher than that of 20's, 30's. In exposed group, working duration has no significant difference. In conclusion, smoking was the most hazardous factor to elevate in blood heavy metal levels.

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Effect of Additives on Transmittance of Tick Film Prints in PDP

  • Jun, Jae-Sam;Cha, Myung-Ryoung;Kim, Yu-Jin;Kim, Hyung-Sun
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.544-547
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    • 2004
  • Glass frits for dielectric layers are mostly used for screen printing process. Several additives have already been known to be well matched with lead-oxide glasses system. The use of lead oxide, however, creates environmental problems, so many recent studies on lead-free glasses compositions have been carried out. A study of the suitability between additives and lead-free glass system is needed. In this study, we have used a screen-printing method to make thick films of lead-oxide glass and lead-free glass using different additives, and analyzed and compared the transmittance of the thick films.

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Optimization of Conduction-cooled Pottier Current Leads (전도냉각형 펠티어 전류도입선의 최적화)

  • Jeong, Eun-Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.8
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    • pp.764-771
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    • 2005
  • A theoretical investigation for optimization of conduction-cooled Peltier current leads is undertaken. A Pottier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high Tc superconductor (HTS) lead in the order of decreasing thermoelectric tempera ture. Mathematical expression for the minimum heat flow per unit current crossing the TE metal interface and that flowing from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE-metal interface possesses a unique optimal value that minimizes the heat flow to the joint and that this optimal value depends on the material properties of the 73 and the metallic lead but not the joint temperature nor electric current. It is also shown that there exists a unique optimal value for the joint temperature between the metal and the HTS leads that minimizes the sum of the power dissipated by ohmic heating in current leads and the refrigerator power consumed to cool the lead, for a given length of the HTS.

Preparation of Purified Lead Nitrate from Lead Sulfate Generated from the Lead-acid Battery Smelter as By-products (재생연 제련 부산물인 황산연으로부터 정제 질산연의 제조)

  • Lee, Jin-Young;Han, Choon;Shin, Joong-Kuk;Kim, Saung-Gyu;Lee, Hwa-Young;Oh, Jong-Kee
    • Resources Recycling
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    • v.7 no.2
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    • pp.31-38
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    • 1998
  • Hydrometallugical process was developed to produce the purified lead nitrate from lead dust mainly composed of lead s sulfate generated from lead-acid battery smelter as by-product. This process consisLed of carbonation process with carbonate s salts, leaching and purification processes. FmaJJy crude lead nitrate purified to produce high-purity product with over 99% Pb $(NO_3)_2$.

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Thermal Stability of the Mechanical and Thermal Conductive Properties on Cu-STS-Cu Clad Metal for LED Package Lead Frame (LED 리드프레임 패키징용 Cu/STS/Cu 클래드 메탈의 기계 및 열전도 특성의 온도 안정성 연구)

  • Kim, Young-Sung;Kim, Il-Gwon
    • Journal of Welding and Joining
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    • v.31 no.5
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    • pp.77-81
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    • 2013
  • We have investigated thermal stability of the mechanical and thermal conductive properties of Cu/STS/Cu 3 layered clad metal lead frame material for a LED device package at different temperatures ranging from RT to $200^{\circ}C$. The fabricated Cu/STS/Cu clad metal has a good thermal stability for the mechanical tensile strength and thermal conductivity of the over 50 $Kg/mm^2$ to the $150^{\circ}C$ and 270 $W/m{\cdot}K$ to the $200^{\circ}C$, respectively. This clad metal lead frame material at a high temperature of $150^{\circ}C$ shows a reinforced mechanical tensile strength by 1.5 times to conventional pure copper lead frame materials and also a comparable thermal conductivity to typical copper alloy lead frame materials.

Fabrication of the Cu-STS-Cu Clad Metal for High Strength Electric Device Lead Frame and Thermal Stability on Their Physical Properties (고강도 전자소자 리드프레임용 Cu/STS/Cu 클래드 메탈제조 및 물리적특성에 대한 열안정성 연구)

  • Kim, Il-Gwon;Son, Moon-Eui;Kim, Young-Sung
    • Journal of Welding and Joining
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    • v.32 no.5
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    • pp.80-86
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    • 2014
  • We have successfully fabricated high strengthening Cu/STS/Cu 3 layered clad metal of $70kgf/mm^2$ grade for electric device lead frame, and investigated thermal effect of the mechanical and physical properties on the Cu/STS/Cu 3 layered clad metal lead frame material at different temperatures ranging from RT to $200^{\circ}C$. The fabricated clad metal shows a good thermal stability under 6% degrading of mechanical tensile strength and hardness change at $200^{\circ}C$ and also physical properties show stable thermal and electrical conductance of over $220W/m{\cdot}K$ and 58.44% IACS upto the $200^{\circ}$. The results confirm that fabricated high strengthening Cu/STS/Cu 3 layered clad metal can be applied for the high performed electrical lead frame devices.

pH Effect on Lead Transport into astrocytes by Divalent Metal Transporter 1 (DMT1/Nramp2)

  • Cheong, Jae-Hoon;Desmond I. Bannon;Josep P. Bressler
    • Proceedings of the Korean Society of Applied Pharmacology
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    • pp.91-91
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    • 2001
  • Nramp2, also known as DMT1 and DCT1, is a 12-transmembrane domain protein responsible for dietary iron uptake as well as metal ions such as lead, manganese, zinc, copper, nickel, cadmium, and cobalt. High expression of DMT1 increase lead uptake, and DMT1-dependent lead transport was H -dependent and inhibited by iron ions. The molecular mechanism of lead transport in CNS is as yet unknown. although interactions between iron and lead at the level of absorption have been known for some time. The process of lead uptake into astrocytes was not known yet. Nramp2 may mediate transport of heavy metal into astrocytes. We investigated whether Nramp2 mediate transport of lead into astrocytes. And we do whether Nramp2 was expressed highly by deprivation of iron in Astrocytes, and lead uptake into astrocytes was influenced by expression of Nramp2. Immortalized human fetal astrocyte(SV-FHA) cells were cultured in medium containing Dulbecco's modified Eagle's medium and treated with Deferoxamine. Northern blot analysis was done for determining mRNA level of DMT1 and lead uptake assay was done in incubation condition of pH 5.5 and 7.4.

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