• Analytical Science and Technology
• /
• v.9 no.3
• /
• pp.253-261
• /
• 1996

Analytical method for the determination of trace germanium in inorganic matrices by differential pulse polarography(DPP) was studied. The reduction peak of germanium(IV) in perchloric acid solution containing 1, 2, 3-trihydroxy benzene appeared at -0.45V(vs. Ag/AgCl) and the peak current for germanium complex varied linearly with concentration variation. Factors affecting sensitivity and precision for germanium quantification were studied and detection limit under the investigated parameters was 1ng/ml. Inorganic samples were decomposed by fusion with potassium pyrosulfate. Serious interferences of Se(IV), Pb(II), As(III) for the determination of germanium were discussed. Interferences of these elements could be avoided by extraction of germanium from decomposed matrices by $CCl_4$ in 10M HCl solution. The germanium contents of inorganic samples(Pb bf. dust, Cu bf. dust, gneiss, Cu anode slime) were determined by the above method.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.250-253
• /
• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. The Ni contact was formed on the front grid pattern by electroless plating followed by anneal ing at $380{\sim}400^{\circ}C$ for $15{\sim}30$ min at $N_{2}$ gas to allow formation of a nickel-silicide in a tube furnace or a rapid thermal processing(RTP) chamber because nickel is transformed to NiSi at $380{\sim}400^{\circ}C$. The Ni plating solution is composed of a mixture of $NiCl_{2}$ as a main nickel source. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. The Ni/Cu contact was found to be well suited for high-efficiency solar cells and was successfully formed by using electroless plating and electroplating, which are more cost effective than vacuum evaporation. In this paper, we investigated low-cost Ni/Cu contact formation by electroless and electroplating for crystalline silicon solar cells.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.673-679
• /
• 1991

The electrochemical reduction of N-tert-butylbenzothiazole-2-sulfenamide (TBBS; vulcanization accelerator) was investigated by direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The electrode reduction of TBBS proceeded E-C-E-C reaction mechanism by four electrons transfer at irreversible one wave (-2.31 volts vs. Ag/0.1M AgN$O_3$ in AN). As the results of controlled potential electrolysis, mercaptobenzothiazole (MBT), benzothiazole disulfide (MBT dimer) and extricated sulfur were products which followed by cleavage of the sulfenamide (-S-N=) bond. Upon the basis of products analysis and polarogram interpretation with pH variable, electrochemical reaction mechanism was suggested.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.680-688
• /
• 1991

The electrochemical reduction of N-oxyldiethylenebenzothiazole-2-sulfenamide (ODBS; vulcanization accelerator) was investigated by direct current polarography, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The irreversible electrode reduction of ODBS proceeded E-C-E-C reaction mechanism by three electrons transfer with irreversible one wave (-1.86 volts vs. Ag/0.1 M AgN$O_3$ in AN). As the results of controlled potential electrolysis, mercaptobenzothiazole (MBT), benzothiazole disulfide (MBT dimer) and extricated sulfur were products which followed by cleavage of the sulfenamide (-S-N=) bond. Upo the basis of products analysis and polarogram interpretation witli pH variable, electrochemical reaction mechanism was suggested.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.81-81
• /
• 2010

전자 패키징은 미세화, 경량화, 저가화를 지향하고 신뢰성의 향상을 위해 발전해 왔다. 이러한 경향은 전자부품 자체의 성능 향상 뿐 아니라 전자부품을 장착, 고정할 수 있게 하는 인쇄회로 기판(PCB : Printed Circuit Board)의 성능에 많은 관심을 가지게 되었다. 전기적 신호의 손실을 줄이기 위해 전기, 전자 산업체에서는 가볍고 굴곡성이 우수한 연성인쇄회로기판(FPCB : Flexible PCB)과 가격이 싸고 신뢰성이 입증된 경성인쇄회로기판(RPCB : Rigid PCB)이 그 대상이다. 본 논문에서는 이 PCB중에서도 RPCB와 FPCB간의 열압착 방식으로 접합 시 전극간의 접합 양상을 보았다. 이 열압착 방식은 기존에 PCB를 접합하는데 사용하고 있는 connector를 이용한 체결법을 대체하는 기술로써 솔더를 중간층(interlayer)로 이용하여 열과 압력으로 접합하는 방식이다. 이 방식을 connector를 사용하는 방식에 비해 그 부피가 작고 I/O개수에 크게 영향 받지 않으며 자동화 공정이 쉬운 장점을 가지고 있다. 접합의 대상 중 RPCB의 경우는 무전해 니켈 금도금(ENIG : Electroless Nickle Immersion Gold)로 제작하였으며 FPCB의 경우는 ENIG와 유기보호피막(OSP : Organic solderability preservation) 처리하였다. 실험에 사용한 PCB는 $300\;{\mu}m$ pitch의 미세피치이며 솔더의 조성은 Sn-3.0Ag-0.5Cu (in wt%)과 Sn-3.0Ag (in wt%)를 사용하였다. 접합 온도와 접합 시간 그리고 접합 압력에 따라 최적의 접합 조건을 도출하였다. 접합 강도는 $90^{\circ}$ Peel Test를 통해서 측정하였으며 접합면 및 파괴면은 SEM과 EDS를 통하여 분석하였다.

• Journal of the Korean Chemical Society
• /
• v.33 no.6
• /
• pp.614-622
• /
• 1989

The electrochemical reduction of ${\alpha},{\beta}$-dibenzyl N-benzylidene L-aspartate in 0.1M LiCl ethanol solution was investigated by direct current (DC), differential pulse (DP) polarography, cyclic voltammetry and controlled potential coulometry(CPC). The irreversible reductive amination of imino group proceeded to form ${\alpha},{\beta}$-dibenyl N-benzyl L-aspartate by CEC or CE electrochemical reaction mechanism at the first reduction step (-0.92 volts vs. Ag-AgCl). The polarographic reduction wave was slightly suppressed due to inhibitory effect of micelle, while the irreversibility was increased according to the increase of Triton X-100 concentration. Upon the basis of product analysis and polarogram interpretation with pH change, possible CE electrode reaction mechanism was suggested.

• Journal of the Korean Chemical Society
• /
• v.36 no.1
• /
• pp.44-50
• /
• 1992

The ability to account for magnetic and spectra properties of complexes was investigated for the splitting of the degenerate d-orbitals and with nonaqueous solution by UV/vis-spectrophotometric method. The correlation of the magnetitude of 10Dq obtained from the spectra, the pairing energy, and the spin state of the complexes. The electrochemical behavior of complexes were investigated by the use of cyclic voltammetry in aprotic media. These reduction peak of $[(C_6H_5)3_P]_2Pd(II)(CH_3COO)_2$ and $[(C_6H_5)_3Pd]_2Pd(II)Cl_2$ were irreversible one-electron processes at peak $E_{pc1} = -1.32 V,\;E_{pc2} = -1.56 V$ and $E_{pc1} = -1.74 V,\;E_{pc2} = -1.88 V$ of these complexes vs. Ag/AgCl, but nickel complexes were not to be reducible.

• Journal of the Korean Chemical Society
• /
• v.35 no.1
• /
• pp.70-77
• /
• 1991

1-Benzyl-4-iodomethyl-2-azetidinone(BIMA) was synthesized and its electrochemical reduction was investigated by direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The irreversible two electron transfer on reductive dehalogenation of iodo group proceeded to form 1-benzyl-4-methyl-2-azetidinone by EEC electrode reaction mechanism at the first reduction step(-1.35 volts vs. Ag-AgCl). The polarographic reduction waves separated into two reduction steps due to anionic surfactant (sodium lauryl sulfate) effects, while the waves were shifted to the positive potential as the concentration of cationic surfactant (cetyltrimethylammonium bromide) increased. Upon the basis of results on the product analysis and interpretation of polarogram with pH variable, EEC electrochemical reaction mechanism was suggested.

• The Korean Journal of Physiology
• /
• v.20 no.1
• /
• pp.9-15
• /
• 1986

The effect of dopamine on the propagation and the frequency electrical activities (slow wave) of the stomach was studied in isolated stomach muscle strips of 145 cats, The gastric slow wave monopolarly recorded by four capillary electrodes (Ag-AgCl) in Krebs-Ringer solution $(ph\;7.4,\;temperature\;36{\pm}0.5^{\circ}C)$ bubbled with 5% $CO_2$ in $O_2$. Dopamine caused concentration-dependent changes of direction of slow wave propagation with decline in development of irregular propagation by domperidone pretreatment. Dopamine also increased the variation of slow wave frequency concentration-dependently. The variation of slow wave frequency induced by dopamine was significantly inhibited by pretreatment with domperidone and phentolamine but not with propranolol, hexamethonium and tetrodotoxin. It is therefore suggested that dopamine plays a role in the genesis of gastric electrical abnormality acting on dopamine receptors and partly on ${\alpha}-adrenergic$ receptors in cats.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.192-193
• /
• 2007

An evaporated Ti/Pd/Ag contact system is most widely used to make high-efficiency silicon solar cells, however, the system is not cost effective due to expensive materials and vacuum techniques. Commercial solar cells with screen-printed contacts formed by using Ag paste suffer from a low fill factor and a high shading loss because of high contact resistance and low aspect ratio. Low-cost Ni and Cu metal contacts have been formed by using electro less plating and electroplating techniques to replace the Ti/Pd/Ag and screen-printed Ag contacts. Ni/Cu alloy is plated on a silicon substrate by electro-deposition of the alloy from an acetate electrolyte solution, and nickel-silicide formation at the interface between the silicon and the nickel enhances stability and reduces the contact resistance. It was, therefore, found that nickel-silicide was suitable for high-efficiency solar cell applications. Cu was electroplated on the Ni layer by using a light induced plating method. The Cu electroplating solution was made up of a commercially available acid sulfate bath and additives to reduce the stress of the copper layer. In this paper, we investigated low-cost Ni/Cu contact formation by electro less and electroplating for crystalline silicon solar cells.