• Journal of the Microelectronics and Packaging Society
• /
• v.22 no.1
• /
• pp.43-49
• /
• 2015

By the trends of electronic package to be smaller, thinner and more integrative, organic printed circuit board is required to be finer Cu trace pitch. This paper reports on a study of failure mechanism for PCB with fine Cu trace pitch using biased HAST. In weibull analysis of the biased HAST lifetime, it is found that the acceleration factor (AF) of between $135^{\circ}C/90%RH/3.3V$ and $130^{\circ}C/85%RH/3.3V$ is 2.079. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the failure mode. It is found that $Cu_xO/Cu(OH)_2$ colloids and Cu dendrites were formed at anode (+) and at cathode (-), respectively. Thus, this gives the evidence that Cu dendrites formed at cathode by $Cu^{2+}$ ion migration lead to a short failure between a pair of Cu nets.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.2 no.2
• /
• pp.126-131
• /
• 1997

The biosorption and desorption of Cr, Cu and Al were carried out using brown marine algae Sargassum fluitans biomass, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by physical and chemical pretreatment. The maximum uptake of Cr, Cu and Al was independent of the alginate content. The maximum uptaker of Al was two times(mole basis) than those of Cu and Cr. The aluminum-alginate complex was found in the sorption solution of raw and protonated biomass. Most of Cu, Al and light metals sorbed in the biomass were eluted at pH 1.1. However, only 5 to 10% of Cr sorbed was eluted at pH 1.1. The stoiceometric ion exchange between Cu and Ca ion was observed on Cu biosorption with Ca-loaded biomass. A part of Cr ion was bound to biomass as Cr(OH)2+ or Cr(OH)2+. Al was also bound to biomass as multi-valence ion and interfered with the desorbed Ca ion. The behavior of raw S. fluitans in ten consecutive sorption-desorption cycles has been investigated in a packed bed flow-through-column during a continuous removal of copper from a 35 mg/L aqueous solution at pH 5. The eluant used was a 1%(w/v) CaCl2/HC solution at pH 3.

• Korean Journal of Materials Research
• /
• v.13 no.8
• /
• pp.524-530
• /
• 2003

In order to prepare the uniform copper particles from copper sulfate solution by using hydrazine as a reduction agents, the reduction behavior of copper particles from copper sulfate was investigated in detail at room temperature by the observation of reaction products. The effects of $NH_4$OH and $Na_4$$P_2$$O_{7}$ on the formation of uniform copper particles were discussed. ($NHCu_3$)$_4$$SO_4$was completely formed at over pH 11 by adding $NH_4$OH in copper sulfate solution. The fine $Cu_2$O with the particle size of 50 nm was produced in the initial reduction process of (NH$Cu_3$)$_4$$SO_4$solution with $Na_4$$P_2$$O_{ 7}$ and then the Cu$_2$O was converted into copper particles by inserting additional hydrazine. When Cu(NH$_3$)$_4$SO$_4$solution with $Na_4$$P_2$$O_{ 7}$ was reduced at $80^{\circ}C$ by hydrazine, the highly dispersed copper particles with the particle size of about 0.8 $\mu\textrm{m}$ was obtained.

• Journal of Industrial Technology
• /
• v.27 no.A
• /
• pp.195-202
• /
• 2007

Milled Korean pine (Pinus densiflora) wood was used to evaluate its adsorption capacity of Cu(II) ions from aqueous solution by running a series of batch experiments. Prior to the tests, the milled woods were pretreated with 1N NaOH, 1N $HNO_3$, and distilled water, respectively, to examine the effect of pretreatment. Within the tested pH range between 3 and 6, copper adsorption efficiency of NaOH-treated wood(96~99%) was superior to the $HNO_3$-treated wood(19~31%) and distilled water-treated wood(18~35%). The efficiency of copper removal by wood enhanced with increasing solution pH and reached a maximum copper ion uptake at pH 5~6. Adsorption behavior of copper onto both raw and $HNO_3$-treated woods was mainly attributed to interaction with carboxylic acid group. For NaOH-treated wood, carboxylate ion produced by hydrolysis or saponification was a major functional group responsible for Cu sorption. NaOH treatment of wood changed the ester and carboxylic acid groups into carboxylate group, whereas $HNO_3$ treatment did not affect the production of functional groups which could bind copper. A pseudo second-order kinetic model fitted well for the sorption of copper ion onto NaOH-treated wood. A batch isotherm test using NaOH-treated wood showed that equilibrium sorption data were better represented by the Langmuir model than the Freundlich model.

• Korean Journal of Materials Research
• /
• v.6 no.2
• /
• pp.158-165
• /
• 1996

열증착기(thermal evaporator)로 증착시킨 Cu를 상온에서 3.5M CuCl2+0.5M HCI+0.5MKCI 용액을 사용하여 습식각하고 2일간 대기중 노출시킨 후 X-선 광전자 분광기를 이용하여 표면의 결합상태를 관찰하였다. 그 결과 습식식각된 Cu 표면에서는 C, O, Ci 및 Cu가 존재함을 알 수 있었다. 표면원소에 대한 오제이 전자 스펙트라(Auger electron spectra)와 광전자 스펙트라(photoelectron spectra)의 정량적인 비교를 통하여 표면의 모든 결합상태를 확인할 수 있었고 그 상대적인 양까지도 얻어낼 수 있었다. 식각된 Cu의 표면에는 Cu-Cu, 2Cu-O, Cu-Ci, Cu-2(OH), 및 Cu-2Cl의 결합상태가 존재함을 알 수 있었고, CuLMMAuger line spectrum의 관찰을 통하여 계산된 각 결합의 정량적인 비교를 검증할 수 있었다. 따라서 chemical shift가 거의 관찰되지 않아 결합상태 분리가 불가능한 식각된 구리표면의 정량적 결합상태는 각 결합상태의 상대적 비교를 통하여 얻어질 수 있음을 알 수 있었다.

• Journal of the Microelectronics and Packaging Society
• /
• v.25 no.4
• /
• pp.75-81
• /
• 2018

The effect of $Ar-N_2$ plasma treatment on Cu surface as one of solutions to realize reliable Cu-Cu wafer bonding was investigated. Structural characteristic of $Ar-N_2$ plasma treated Cu surface were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscope. Ar gas was used for a plasma ignition and to activate Cu surface by ion bombardment, and $N_2$ gas was used to protect the Cu surface from contamination such as -O or -OH by forming a passivation layer. The Cu specimen under high Ar partial pressure plasma treatment showed more copper oxide due to the activation on Cu surface, while Cu surface after high $N_2$ gas partial pressure plasma treatment showed less copper oxide due to the formation of Cu-N or Cu-O-N passivation layer. It was confirmed that nitrogen plasma can prohibit Cu-O formation on Cu surface, but nitrogen partial pressure in the $Ar-N_2$ plasma should be optimized for the formation of nitrogen passivation layer on the entire surface of Cu wafer.

• Journal of Powder Materials
• /
• v.21 no.3
• /
• pp.191-195
• /
• 2014

This study reports a simple way of fabricating the porous Cu with unidirectional pore channels by freeze drying camphene slurry with Cu oxide coated Cu powders. The coated powders were prepared by calcination of ball-milled powder mixture of Cu and Cu-nitrate. Improved dispersion stability of camphene slurry could be achieved using the Cu oxide coated Cu powders instead of pure Cu powders. Pores in the frozen specimen at $-25^{\circ}C$ were generated by sublimation of the camphene during drying in air, and the green bodies were sintered at $750^{\circ}C$ for 1 h in $H_2$ atmosphere. XRD analysis revealed that the coated layer of Cu oxide was completely converted to Cu phase without any reaction phases by hydrogen heat treatment. The porous Cu specimen prepared from pure Cu powders showed partly large pores with unidirectional pore channels, but most of pores were randomly distributed. In contrast, large and aligned parallel pores to the camphene growth direction were clearly observed in the sample using Cu oxide coated Cu powders. Pore formation behavior depending on the initial powders was discussed based on the degree of powder rearrangement and dispersion stability in slurry.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1652-1654
• /
• 2000

고상반응법을 이용하여 $Ni_{0.6-x}Cu_{x}Zn_{0.4}Fe_{2}O_4$(x=0, 0.1, 0.2, 0.3) ferrite 분말을 제조하고 1200$^{\circ}C$에서 열처리하여 Cu 첨가에 따른 입자변화와 전자파흡수 특성과의 관계를 조사하였다. Ni를 Cu로 0.1 mol 치환했을 때 까지는 포화자화 및 전자파흡수능이 치환하지 않았을 때와 거의 비슷하였으나, 그 이상 첨 가시는 직선적으로 감소하였다.

• Journal of Electrochemical Science and Technology
• /
• v.11 no.1
• /
• pp.60-67
• /
• 2020

In this study, copper (II) oxide powder for electroplating was prepared by recovering CuCl₂ from NaClO₃ type etching wastes via recovered non-sintering two step chemical reaction. In case of alkali copper carbonate [mCuCo₃·nCu(OH)₂], first reaction product, CuCo₃ is produced more than Cu(OH)₂ when the reaction molar ratio of sodium carbonate is low, since m is larger than n. As the reaction molar ratio of sodium carbonate increased, m is larger than n and Cu(OH)₂ was produced more than CuCO₃. In the case of m has same values as n, the optimum reaction mole ratio was 1.44 at the reaction temperature of 80℃ based on the theoretical copper content of 57.5 wt. %. The optimum amount of sodium hydroxide was 120 g at 80℃ for production of copper (II) oxide prepared by using basic copper carbonate product of first reaction. At this time, the yield of copper (II) oxide was 96.6 wt.%. Also, the chloride ion concentration was 9.7 mg/L. The properties of produced copper (II) oxide such as mean particle size, dissolution time for sulfuric acid, and repose angle were 19.5 mm, 64 second, and 34.8°, respectively. As a result of the hole filling test, it was found that the copper oxide (II) prepared with 120 g of sodium hydroxide, the optimum amount of basic hydroxide for copper carbonate, has a hole filling of 11.0 mm, which satisfies the general hole filling management range of 15 mm or less.

• Knowledge Management Research
• /
• v.16 no.2
• /
• pp.193-212
• /
• 2015

A corporate university (CU) is an educational institution established by an organization whose primary purpose is not education. Traditionally, a CU is considered a training facility to improve organizational performance. However, the proliferation of the CU has engendered its diverse purposes, roles, and forms. This study attempts to identify three types of the existing CUs: (a) a CU to improve organizational performance; (b) a CU to satisfy employees' learning needs; and (c) a CU to develop a competent national workforce. Also, this study suggests a holistic CU model including the three CU types. In order to transform a CU to a multifunctional CU embracing all three types of CU, organizations should (a) provide communication and collaboration channels, (b) present clear organizational goals, (c) establish organizational policies/systems to encourage learning in CUs, and (d) devise an effective approach to evaluate the impact of CUs. Organization' s critical roles in the development of CUs can assist CUs in becoming the core of knowledge management.