• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.65-71
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• 2016

In this study, Antimony Tin Oxide (ATO) ion storage layer and $TiO_2$ working electrode were fabricated using Nano Particle Deposition System. NPDS is the cutting-edge technology among the dry deposition methods. Accelerated particles are deposited on the substrate through the nozzle using NPDS. The thicknesses for coated layers were measured and layer's morphology was acquired using SEM. The fabricated electrochromic cell's transmittance was measured using UV-Visible spectrometer and power source at 630 nm. As a result, the integrated electrochromic/DSSC hybrid system was successfully fabricated as an energy harvesting system. The fabricated electrochromic cell was self-operated using DSSC as a power source. In conclusion, the electrochromic cell was operated for 500 cycles, with 49% of maximum transmittance change. Also the photovoltaic efficiency for DSSC was measured to be 2.55% while the electrochromic cell on the integrated system had resulted in 26% of maximum transmittance change.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.59-63
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• 2017

The n-type GaN semiconductor has excellent properties as a photoelectrode, but it has disadvantage that its reliability is deteriorated due to the photocorrosion because the oxygen reaction occurs on the surface. For this reason, there are fundamental attempts to avoid photocorrosion reaction of GaN surfaces by using the p-type GaN as a photoelectrode where hydrogen generation reaction occurs on the surface. However, p-type GaN has a problem of low efficiency because of its high resistivity and low hole mobility. In this study, we try to improve the photocurrent efficiency by activation process for the p-type GaN. The p-type GaN was annealed for 1 min. at $500^{\circ}C$ in $N_2$ atmosphere. Hall effect measurement system was used for the electrical properties and potentiostat (PARSTAT4000) was used to measure the photoelectrochemical (PEC) characteristics. Consequently, the photocurrent density was improved more than 1.5 times by improving the activation process for the p-type GaN. Also, its reliability was maintained for 3 hours.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.25-29
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• 2020

This study demonstrates direct-patternable amorphous TiO_x resistive switching (RS) device and the fabrication method using photochemical metal-organic deposition (PMOD). For making photosensitive stock solutions, Ti(IV) 2-ethylhexanoate was used as starting precursor. Photochemical reaction by UV exposure was observed and analyzed by Fourier transform infrared spectroscopy and the reaction was completed within 10 minutes. Uniformly formed 20 nm thick amorphous TiO_x film was confirmed by atomic force microscopy. Amorphous TiO_x RS device, formed as 6 × 6 ㎛ square on 4 ㎛ width electrode, showed forming-less RS behavior in ±4 V and on/off ratio ≈ 20 at 0.1 V. This result shows PMOD process could be applied for low temperature processed ReRAM device and/or low cost, flexible memory device.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.4
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• pp.37-42
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• 2007

We fabricated the polymer light emitting diodes (PLEDs) with ITO/PEDOT:PSS/PVK/PFO:MEH-PPV/LiF/Al structures. The effect of the thickness of PEDOT:PSS hole injection layer(HIL) on the electrical and optical properties of PLEDs was investigated. In addition, PVK hole transport layer(HTL) was introduced in the PLED device, and compared the properties of the PLEDS with and without PVX layer. All organic film layers were prepared by the spin coating method on the plasma treated ITO/glass substrates. As the thickness of PEDOT:PSS film layer decreased from about 80 nm to 50 nm, the luminance of PLED device increased from $220cd/m^2$에서 $450cd/m^2$. This may be ascribed to the increased transportation efficiency of the holes into the emission layer of PLED. The maximum current density and luminance were obtained fir the PLED device with PVX hole transport layer, showing that the current density and luminance were $268mA/cm^2\;and\;540cd/m^2$ at 12V, respectively. This values were improved by about 14% and 22% in current density and luminance compared with the PLED device without PVK layer.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.63-67
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• 2011

We investigated effects of bonding conditions on the peel strength of rigid printed circuit board (RPCB)/ flexible printed circuit board (FPCB) joints bonded using a thermo-compression bond method, The electrodes on the FPCB were coated with Sn by a dipping process. We confirmed that the bonding temperature and bonding time strongly affected the bonding configuration and strength of the joints. Also, the peel strength is affected by dipping conditions; the optimum dipping condition was found to be temperature of $270^{\circ}C$ and time of 1s. The bonding strength linearly increased with increasing bonding temperature and time until $280^{\circ}C$ and 10s. The fracture energy calculated from the F-x (Forcedisplacement) curve during a peel test was the highest at bonding temperature of $280^{\circ}C$.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.41-47
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• 2007

Today lots of investigations on Embedded Passive Technology using materials and chip components have been carried out. We fabricated diplexers with 1005 sized-passives, which were made by burying chips in PCB substrate and surface mounting chip on PCB. 6 passive chips (inductors and capacitors) were used for the frequency divisions of $880\;MHz{\sim}960\;MHz(GSM)$ and $1.71\;GHz{\sim}1.88\;GHz(DCS)$. Two types of diplxer were characterized with Network analyzer. The chip buried diplexer showed extra 5db loss and a little deviation of 0.6GHz at aimed frequency areas, whereas the chip mounted diplexer showed man. 0.86dB loss within GSM field and max. 0.68dB within DCS field respectively. But few degradations were observed after $260^{\circ}C$ for 80min baking and $280^{\circ}C$ for 10sec solder floating.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.1
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• pp.7-11
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• 2014

Recently, the buffer layers consisting of poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT-PSS) are extensively used to improve power conversion efficiency (PCE) of organic solar cells. However, PEDOT-PSS is not suitable for mass production of organic solar cells due to its intrinsic acid and hygroscopic properties. Moreover, because of chemical reactions between indium tin oxide (ITO) layer and PEDOT-PSS layer, the interface is not stable. For these reasons, alternative materials such as $V_2O_5$ have been developed to be an effective buffer layer. In this work, we used $V_2O_5$/Ag/ITO multilayer structure for the anode buffer layer. With variation of thickness of Ag layer, we investigated the optical and electrical properties of $V_2O_5$/Ag/ITO multi-layer films. As a result, we found that the electrical properties were improved with increasing Ag thickness while optical transmittance decreases in visible wavelength region. From the calculation of figure of merit (FOM) which is used to evaluate proper structure for transparent of optoelectronic, $V_2O_5$/Ag/ITO multilayer electrode was optimized with 4 nm thick Ag layer in optical (88% in transmittance) and electrical ($4{\times}10^{-4}{\Omega}cm$) properties. This indicates that $V_2O_5$/Ag/ITO multilayer electrode could be a candidate for the anode of optoelectronic devices.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.23-28
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• 2008

To improve the external quantum efficiency by means of the optimization of the polymer light emitting diodes(PLEDs) structure, the PLED with ITO/PEDOT:PSS/(PFO)/PFO:MEH-PPV/LiF/Al structure were fabricated and investigated the electrical and optical properties for the prepared devices. ITO(indium tin oxide) and PEDOT:PSS [poly (3,4-ethylenedioxythiophene): poly(styrene sulfolnate)] were used as transparent anode film and hole transport materials, respectively. PFO[poly(9,9-dioctylfluorene)] and MEHPPV[poly(2-methoxy-5(2-ethylhe xoxy)-1,4-phenylenevinyle)] were used as the light emitting host and dopant materials. The doping concentration of MEH-PPV was 9wt% with thickness of about $400{\AA}$. We investigated the dependence of the PFO thickness ranging from $200{\AA}$ to $300{\AA}$ on the electrical, optical properties of PLEDs. Among prepared PLED devices with different PFO thicknesses, the highest value of the luminance was obtained for the PLED device with $250{\AA}$ in thickness. As a result, the current density and luminance ware found to be about $400mA/cm^2$ and $1500cd/m^2$ at 13V, respectively. In addition, the luminance and current efficiency of PLED device with double emitting layer (PFO/PFO:MEH-PPV) were improved about 3 times compared with the one with single emitting layer (PFO:MEH-PPV).

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.45-50
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• 2017

We investigated effect of Zn content on shear strengh of Sn-0.7Cu-xZn and OSP surface finished solder joints. Five pastes of Sn-0.7Cu-xZn (x=0, 0.5, 1.0, 1.5, 2.0 wt.%) solders were fabricated by mixing of solder powder and flux using planatary mixer. $180{\mu}m$ diameter solder balls were formed on OSP surface finished Cu electrodes by screen print method, and the reflow process was performed. The shear strength was evaluated with two high shear speeds; 0.01 and 0.1 m/s. The thickness of the intermetallic compound(IMC) layer was decreased with increasing Zn content in Sn-0.7Cu-xZn solder. The highest shear strength was 3.47 N at the Zn content of 0.5 wt.%. As a whole, the shear strength at condition of 0.1 m/s was higher than that of 0.01 m/s because of impact stress. Fracture energies were calculated by F-x (Force-displacement) curve during high speed shear test and the tendency of fracture energy and that of shear strength were good agreement each other. Fracture took place within solder matrix at lower Zn content, and fracture occured near the interface of OSP surface finished Cu electrode and solder at higher Zn content.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.11a
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• pp.11-11
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• 2000

이동통신기술의 급격한 발달로 고주파회로의 packaging과 interconnect 기술의 고성능화 와 저가격화에 대한 새로운 도전이 요구되고 있다‘ 대부분 기존의 무선통신 부품은 P PCB(Printed Wiring Board)기술을 활용하고 있으나 이러한 기술이 점차로 고주파화되는 경 향을 만족시킬수 없어 새로운 고주파 부품기술이 요구되고 있는 실정이다 .. RF 회로를 구성 하기 위하여 PCB소재의 환경적, 치수안정성 문제를 극복하기 위하여 L TCC(Low T Temperature Cofired Ceramics)기술이 최근 주목을 받고 있다. 차세대 이동통신 기술은 수십 GHz 이상의 고주파특성이 우수하고, 고성능의 초소형의 부품을 저가격으로 제조할수 있으며, 시장의 변화에 기민하게 대처할수 있는 기술이 요구되 고 있으며, 이러한 기술적 필요성에 부합할수 있도록 LTCC 기술이 제안되었다. 이러한 C Ceramic Interconnect 기술은 높은 신뢰성을 바탕으로 fine patterning 기술과 저가의 m metallizing 기술로 가능하게 되었다. 초고주파 통신부품기술은 미국과 유럽 등을 중심으로 G GHz 대역또는 mm wave 대역의 기술에 대하여 치열한 기술개발 경쟁을 벌이고 있으며, 이 러한 고주파 패키징 기술을 바탕으로 미래의 군사, 항공, 우주 및 이동통신 기술에 지대한 영향을 미칠수 있는 기반기술로 자리잡을 전망이다. L LTCC 기술은 기존의 후막혼성기술에 비하여 공정이 단순하고 대량생산이 가능하고 가 격이 비교적 저렴하다. 또한 다층구조로 제작할수 있고, 수동소자를 내장할수 있어 회로의 소형화와 고밀도화가 가능하다. 특히 무선으로 초고속 정보를 처리하기 위하여 이동통신기 기의 고주파화가 빠르게 진행됨에 따라서 고분자재료에 비하여 고주파특성이 우수할뿐아니 라 환경적, 치수안정성이 우수한 세라믹소재플 사용함으로써 고주파 손실율을 저감할 수 있 다 .. LTCC 기술은 후막회로 기술과 tape dielectric 기술이 결합된 기술이다. 표준화된 소재 와 공정기술을 활용하여 저가격으로 고성능소자플 제작할 수 있으며, 전극재료로서 높은 전 도도를 갖고 있는 Ag, Cu, Au 및 Pd! Ag릎 사용함으로써 고주파 손실을 저감시킬 수 있다. L LTCC 기술이 최종적으로 소형화, 고기능 고주파 부품기술로 지속적으로 발전하기 위하여 무수축(Zero shrinkage) 소성기술, 광식각 후막기술 등이 원천기술로서 확립될 수 있어야 하 며, 특히 국내의 이동통신 기술에 대한 막대한 투자에도 불구하고 차세대 이동통신 부품기 술에 대한 개발은 상대적으로 미흡한 실정이므로 국내에 LTCC 관련 소재공정 및 부품소자 기술에 대한 개발투자가 시급히 이루워져야 할 것으로 판단된다. 본 발표에서는 지금까지 국내외 LTCC 기술의 발전과정을 정리하였고, 현재 이 기술의 응용과 소재와 공정을 중심으로한 개발현황에 대하여 조사하였으며, 앞으로 LTCC가 발전 해야할 방향을 제시하고자 한다.