• Journal of the Microelectronics and Packaging Society
• /
• 제10권4호
• /
• pp.47-52
• /
• 2003

A new type of Bi based glass frit was developed for Ag paste in PDP applications and its properties are compared with the commercially used Pb based glass frit. After optimization of the properties of Bi based frits for PDP application such as the softening temperature and the coefficient of thermal expansion (C.T.E), the screen printed electrodes prepared with the Bi based fit contained Ag paste were characterized. In $Bi_2O_3-B_2O_3-Al_2O_3$ glass system with the more than 50% of $Bi_2O_3$, the softening temperature, the thermal expansion coefficient and the line resistivity was 400∼$480^{\circ}C$, 7.31∼$10.02\times 10^{-6}/^{\circ}C$> and 4.1∼4.8$\Omega$ respectively. Properties of the Bi based frits are comparable with the Pb based frits. A printability and an uniformity of the Bi based frits were excellent in screen printed Ag eletrode. The Bi based frit system is an excellent candidate material for Pb free and Alkali free frit in PDP applications.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 추계학술대회 논문집
• /
• pp.390-390
• /
• 2009

마그네트론 스퍼터링법을 이용하여 n-i-p 구조의 플렉서블 실리콘 박막태양전지용 ZnO/Ag 후면전극을 stainless steel 기판위에 제조하고 증착온도와 Ag 박막의 두께 변화에 따른 광학적 특성변화를 조사하였다. ZnO/Ag 구조의 후면전극은 RF와 DC 마그네트론 스퍼터링으로 Ag 금속 및 ZnO:Al($Al_2O_3$ 2.5%) 세라믹 타겟을 이용하여 각각 제조하였으며 증착온도는 상온 ${\sim}500^{\circ}C$로, Ag 박막두께는 100 ~ 500 nm로 변화시켰다. 증착조건 변화에 따라 제조된 후면전극의 표면거칠기 및 형상변화를 Atomic Force Mircroscope (AFM)와 Scanning electron miroscopy (SEM)으로 분석하였으며 이에 따른 반사도 변화를 UV-visible-nIR spectrometry 측정을 통하여 조사하였다. 증착온도가 증가함에 따라 Ag 박막의 표면 거칠기는 점차로 증가하였으며 증착된 후면전극의 반사도도 함께 증가함을 알 수 있었다. Ag 박막의 두께 변화에 따른 반사도 변화와 n-i-p 구조의 플렉서블 실리콘 박막태양전지에 미치는 영향을 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2008년도 제34회 동계학술대회 초록집
• /
• pp.208-208
• /
• 2008

• Proceedings of the Korean Magnestics Society Conference
• /
• 한국자기학회 2002년도 동계연구발표회 논문개요집
• /
• pp.14-15
• /
• 2002

Iron nitride alloy films prepared in the form of laminated ${(Fe_{97}Al_3)}_{85}N_{15}/Al_2O_3$ multilayers (Ml's) due to excellent soft magnetic properties and high saturation magnetization [1, 2] are very promising materials for poles and shields in ultra high density thin film heads. The present work concerns the ferromagnetic (FM) coupling effect as a function of the thickness of $Al_2O_3$ spacers by analysis of the magnetic domain structure.

• Korean Journal of Materials Research
• /
• 제24권9호
• /
• pp.502-507
• /
• 2014

Recently, improvement in the conversion efficiency of silicon-based solar cells has been achieved by decreasing emitter doping concentration, because the lightly doped emitter can effectively prevent the recombination of electrons and holes generated by solar light irradiation. This type of emitter is very thin due to the low doping concentration, thus conductive materials (i.e., silver) used for front electrodes can easily penetrate the emitter during a firing process because of their large diffusivity in silicon. This results in junction leakage currents which might reduce cell efficiencies. In this study, $Al_2O_3$-coated Ag powders were synthesized by an ultrasonic spray pyrolysis method and applied to the conductive materials of the front electrode to control the junction leakage current. The $Al_2O_3$ shell obstructs the Ag diffusion into the emitter during the firing process. The powder is spherical with a core-shell structure and the thickness of the $Al_2O_3$ shell is tens of nanometers. Solar cells were fabricated using pure Ag powders or the $Al_2O_3$-coated Ag powder as front electrode materials, and the conversion efficiency and junction leakage current were compared to investigate the role of the $Al_2O_3$ shell during the firing processes.

• Journal of the Korean Ceramic Society
• /
• 제50권1호
• /
• pp.50-56
• /
• 2013

Phosphorescent materials coated with titanium dioxide were fabricated and photocatalytic reactions between these materials and VOCs gases were examined. A thin film (approx. 100 nm) of nanosized $TiO_2$ was deposited on the $Sr_4Al_{14}O_{25}$ : $Eu^{2+}$, $Dy^{3+}$, $Ag^+$ phosphor using low-pressure chemical vapor deposition (LPCVD). The characteristics of the photocatalytic reaction were examined in terms of the decomposition of benzene gas using a gas chromatography (GC) system under ultraviolet (${\lambda}$ = 365 nm) and visible light (${\lambda}$ > 420 nm) irradiation. $TiO_2$-coated $Sr_4Al_{14}O_{25}$ : $Eu^{2+}$, $Dy^{3+}$, $Ag^+$ phosphor showed different photocatalytic behavior compared with pure $TiO_2$. $TiO_2$-coated phosphorescent materials showed a much faster photocatalytic decomposition of benzene gas under visible irradiation compared to the pure $TiO_2$ for which the result was practically negligible. This suggests that the extension of the absorption wavelength to visible light occurred through energy band bending by a heterojunction at the interface of the $Sr_4Al_{14}O_{25}-TiO_2$ composite. Also, the $Sr_4Al_{14}O_{25}-TiO_2$ composite showed the photocatalytic decomposition of benzene in darkness due to the photon light emitted from the $Sr_4Al_{14}O_{25}$ phosphors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.27-28
• /
• 2009

In this study, we have fabricated the 3 wt% $Li_2CO3$ doped $(Ba,Sr)TiO_3$ thick films on the Ag/Pd printed $Al_2O_3$ substrates for the LTCCs (Low Temperature Co-fired Ceramics) applications. From the X-ray diffraion analysis, 3 wt% $Li_2CO3$ doped BST thick films on the Ag/Pd printed $Al_2O_3$ substrates, which sintered at 900 $^{\circ}C$ have perovskite structure without any pyro phase. The dielectric properties of 3 wt% $Li_2CO3$ doped BST thick films were measured from 1 kHz to 1 MHz. To investigate the electrical properties of 3 wt% $Li_2CO3$ doped BST thick films, we employed the impedance spectroscopy. The complex impedance of 3 wt% $Li_2CO3$ doped BST thick films were measured from 20 Hz to 1 MHz at the various temperatures.

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.231-231
• /
• 2013

ZnO은 hexagonal wurtzite 구조를 갖는 직접 천이형 화합물 반도체로서, 상온에서 3.37 eV 정도의 wide band gap energy를 가지고 있으며, 60 meV의 큰 엑시톤 결합 에너지(exciton binding energy)를 갖는다. 또한 동종 기판이 존재하고 열, 화학적으로 안정한 상태이며 습식 식각이 가능한 장점으로 인해 각광받고 있다. 또한, ZnO 박막은 우수한 전기 전도성을 나타내며 광학적 투명도가 우수하기 때문에 투명전극으로 많이 이용되어 왔고, 태양 전지(solar cell), 가스 센서, 압전소자 등 많은 분야에서 사용되고 있다. 이와 같은 ZnO박막을 안정적인 쇼트키 다이오드 특성을 얻기 위해서는 쇼트키 배리어 장벽의 형성이 필수적이다. Mg을 ZnO에 첨가하여 MgZnO 박막을 형성할 경우, 금속의 일함수와 MgZnO의 전자친화력 차이가 증가하여 더 큰 쇼트키 장벽 형성이 가능하며, 금속의 일함수가 큰 물질을 사용해야 한다. 또한, 박막의 결함이 적은 박막을 형성해야 하는 에피탁셜 박막이 필요하다. SiC는 높은 포화 전자 드리프트 속도(${\sim}2.7{\times}107$ cm/s), 높은 절연 파괴전압(~3 MV/cm)과 높은 열전도율(~5.0W/cm) 특징을 가지고 있으며, MgZnO/Al2O3의 격자 불일치는 ~19%인 반면에 MgZnO/SiC의 격자 불일치는 ~6%를 가진다. 금속의 일함수가 큰 Ag 금속은 열처리가 될 경우 AgOx가 될 경우 더욱 안정적인 쇼트키 장벽을 형성될 수 있을 것으로 판단된다. 본 연구에서는 쇼트키 접합을 형성하기 위해 금속의 일함수가 큰 Ag 금속을 사용하였으며, Al2O3 기판과 6H-SiC 기판위에 MgZnO(30 at.%) 박막을 증착하였다. 증착 후에 Ag를 증착 한 뒤 급속 열처리를 하였다. 열처리된 MgZnO의 경우 열처리 하지않은 소자보다 약 $10^5$ 이상의 우수한 on/off 특성을 보였다.

• Journal of the Microelectronics and Packaging Society
• /
• 제31권2호
• /
• pp.1-8
• /
• 2024

Bonding wires are composed of conductive metals of Au, Ag & Cu with excellent electrical conductivities for transmitting power and signals to wafer chips. Wire metals do not provide electrical insulation, adhesion promoter and corrosion passivation. Adhesion between metal wires is extremely weak, which is responsible for wire cut failures during thermal cycling. Organic coating for electrical insulation does not satisfy bondability and manufacturability, and it is complex to apply very thin organic coating on metal wires. Automotive packages require enhanced reliability of packages under harsh conditions. LED and power packages are susceptible to wire cut failures. Contrary to conventional OCB behaviors, forming gas was not required for free air ball formation for both Ag and Pd-coated Cu wires with Al₂O₃ passivation.

• Journal of Welding and Joining
• /
• 제13권3호
• /
• pp.134-146
• /
• 1995

Aluminium nitride(AlN) is currently under investigation as potential candidate for replacing alumium oxide(Al$_{2}$ $O_{3}$) as a substrate material for for electronic circuit packaging. Brazing of aluminium nitride(AlN) to Cu with Ag base active alloy containing Ti has been investigated in vacuum. Binary Ag$_{98}$ $Ti_{2}$(AT) and ternary At-1wt.%Al(ATA), AT-1wt.%Ni(ATN), AT-1wt.% Mn(ATM) alloys showed good wettability to AlN and led to the development of strong bond between brate alloy and AlN ceramic. The reaction between AlN and the melted brazing alloys resulted in the formation of continuous TiN layers at the AlN side iterface. This reaction layer was found to increase by increase by increasing brazing time and temperature for all filler metals. The bond strength, measured by 4-point bend test, was increased with bonding temperature and showed maximum value and then decreased with temperature. It might be concluded that optimum thickness of the reaction layer was existed for maximum bond strength. The joint brazed at 900.deg.C for 1800sec using binary AT alloy fractured at the maximum load of 35kgf which is the highest value measured in this work. The failure of this joint was initiated at the interface between AlN and TiN layer and then proceeded alternately through the interior of the reaction layer and AlN ceramic itself.