• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.207-207
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• 2008

Modern industry has focused on processing that produce low- loss dielectric substrates used complex micron-sized devices using tick film technologies such as tape casting and slip casting. However, these processes have inherent disadvantages fabricating high density interconnect with embedded passives for high speed communication electronic devices. Here, we have successfully fabricated porous alumina dielectric layer infiltrated with polymer solution by using inkjet printing process. Alumina suspensions were formulated as dielectric ink that were optimized to use in inkjet process. The layer was confirmed by field emission scanning electron microscope (FE-SEM) for measuring microstructure and volume fraction. In addition, the reaction kinetics and electrical properties were characterized by FT-IR and the impedance analyzer. The volume fraction of alumina in porous dielectric alumina layer is around 70% much higher than that in the conventional process. Furthermore, after infiltration on the dielectric layer using polymer resins such as cyanate ester. Excellent Q factors of the dielectric is about 200 when confirmed by impedance analyzer without any high temperature process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.11
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• pp.683-687
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• 2017

We investigated the structure of an ultra-thin insulating board with low thermal conductivity along z-axis, which was based on the idea of void layers created during the glass infiltration process for the zero-shrinkage low-temperature co-fired ceramic (LTCC) technology. An alumina and four glass powders were chosen and prepared as green sheets by the tape casting method. After comparison of the four glass powders, bismuth glass was selected for the experiment. Since there is no notable reactivity between alumina and bismuth glass, alumina was selected as the supporting additive in glass layers. With 2.5 vol% of alumina powder, glass green sheets were prepared and stacked alternately with alumina green sheet to form the 'alumina/glass (including alumina additive)/alumina' structure. The stacked green sheets were sintered into an insulating substrate. Scanning electron microscopy revealed that the additive alumina formed supporting bridges in void layers. The depth and number of the stacking layers were varied to examine the insulating property. The lowest thermal conductivity obtained was 0.23 W/mK with a $500-{\mu}m-thick$ substrate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.667-672
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• 2006

Ferroelectric $Pb(Zr_{0.52}Ti_{0.48})O_3$ (PZT(52/48)) thick films were fabricated by the screen-Printing method on the alumina substrates, and $PbTiO_3$ (PT) Precursor solution, which prepared by sol-gel method, was spin-coated on the PZT(52/48) thick films to obtain a densification. Its structural and electrical properties of the PZT(52/48) thick films with the treatment of PT precursor solution coating were investigated. The particle size of the thick films was increased with increasing the number of coatings and the thickness of the PZT-6 (6: number of coatings) films was about $60{\mu}m$. The relative dielectric constant increased and the dielectric loss decreased with increasing the number of PT sol coatings. The relative dielectric constant and dielectric loss of the PZT-6 thick film were 475 and 2 %, respectively. The remanent polarization, coercive field and breakdown strength of the PZT-6 film were $32.6{\mu}C/cm^2$, 15 kV/cm and 60 kV/cm, respectively.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.527-530
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• 2009

$(Ba_{0.57}Sr_{0.33}Ca_{0.10})TiO_3$(=BSCT) powders, prepared by the sol-gel method, were doped using $MnCO_3$ as the acceptor and $Dy_2O_3$ as the donor. This powder was mixed with an organic vehicle. BSCT thick films were fabricated by the screen-printing techniques on the alumina substrate. The structural and dielectric properties of BSCT thick films were investigated with variation of the $Dy_2O_3$ amount. As a result of the differential thermal analysis (DTA), the exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All the BSCT thick films showed the XRD patterns of a typical polycrystalline perovskite structure. The average grain size of BSCT thick films decreased with an increasing amount of $Dy_2O_3$. The relative dielectric constant and dielectric loss of the BSCT thick film doped $Dy_2O_3$ 0.1mol% were 4637.4 and 1.6% at 1kHz, respectively.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1418-1419
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• 2006

PZT(80/20) powder was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The coating and drying procedure was repeated 4 times. And then the PZT(20/80) precursor solution was spin-coated on the multilayered thick films. A concentration of a coating solution was 0.5 mol/L and the number of coating was repeated from 0 to 6. The porosity of the thick films was decreased with increasing the number of coatings and the PZT thick films with 6-times coated showed the dense microstructure and thickness of about 60-65 ${\mu}m$. All PZT thick films showed the typical XRD patterns of a typical perovskite polycrystalline structure. The relative dielectric constant and the dielectric loss of the PZT-6 thick film were 275 and 3.5, respectively. And the PZT-6 film shows the remanent polarization of 22.1 $C/cm^2$ and coercive field of 13.7 kV/cm.

• Journal of the Korean Magnetics Society
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• v.23 no.4
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• pp.126-129
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• 2013

We have fabricated an ordered Ni nanodot structure using an alumina mask prepared via 2-step anodization technique under phosphoric acid. We have formed a porous structure with average pore size of 279 nm on $2{\mu}m$ thick alumina film and the thermal deposition of thin Ni film though the mask led to the formation of ordered Ni nanodot structure with an average dot size of 293 nm, following the pore structure on the mask. We further investigated the magnetic properties of the nanodot structure by measuring the hysteresis curve at room temperature. When compared to the magnetic properties of a continuous Ni film, we observed the decrease in the squareness and the increase in coercivity along the magnetization easy axis, due to the isolated nanodot structure. Our study suggests that the ordered nanodot structure can be easiy fabricated with thin film deposition technique using anodized alumina mask as a mask.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.685-688
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• 2003

[ $(Ba,Sr,Ca)TiO_3$ ] powders, prepared by the sol-gel method, were mixed with an organic vehicle and the BSCT thick films were fabricated by the screen printing techniques on alumina substrates. The grain size decreased with increasing amounts of $MnO_2$, and the BSCT(50/40/10) thick film doped with 1wt% $MnO_2$ showed a value of 6.5mm. The thickness of thick films by four-cycle on printing/drying was approximately 100mm. The relative dielectric constant, dielectric loss and tunability of the BSCT(S0/40/10) thick films doped with 1.0wt% $MnO_2$ were 1296, 0.61% and 11.18%, respectively.

• Journal of Powder Materials
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• v.22 no.6
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• pp.438-442
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• 2015

Porous thick film of alumina which is fabricated by freeze tape casting using a camphene-camphor-acrylate vehicle. Alumina slurry is mixed above the melting point of the camphene-camphor solvent. Upon cooling, the camphene-camphor crystallizes from the solution as particle-free dendrites, with the $Al_2O_3$ powder and acrylate liquid in the interdendritic spaces. Subsequently, the acrylate liquid is solidified by photopolymerization to offer mechanical properties for handling. The microstructure of the porous alumina film is characterized for systems with different cooling rate around the melting temperature of camphor-camphene. The structure of the dendritic porosity is compared as a function of ratio of camphene-camphor solvent and acrylate content, and $Al_2O_3$ powder volume fraction in acrylate in terms of the dendrite arm width.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.9
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• pp.429-433
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• 2006

PZT(80/0) powder was prepared by a sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The coating and drying procedure was repeated 4 times. And then the PZT(20/80) precusor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5mol/L and the number of coating was varied from 0 to 6. The porosity decreased and the grain size increased with increasing the number of coatings. The thickness of the PZT-6(6: number of coatings) films was about $60{\mu}m$. The relative dielectric constant increased and the dielectric loss decreased with increasing the number of PZT(20/80) sol coatings. The relative dielectric constant and dielectric loss of the PZT-6 thick film were 275 and 3.5%, respectively. The remanent polarization, coercive field and breakdown strength of the PZT-6 film were $19.8{\mu}C/cm^2$, 13.7kV/cm and 130kV/cm, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1621-1625
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• 2010

Recently, due to increase in the usage of toxic gas and inflammability gas, the ability to monitor and precisely measurement of these gases is crucial in preventing the occurrence of various accidents. CuO doped and undoped $WO_3$ thick films gas sensors were prepared using screen-printing method on alumina substrates. A structural properties of $WO_3$:CuO thick films had monoclinic phase and triclinic phase of $WO_3$ together. Sensitivity of $WO_3$:CuO sensor at 2000 ppm of $CO_2$ gas and 50 ppm of $H_2S$ gas was investigated. 4 wt% Cu doped $WO_3$ thick films had the highest sensitivity of $CO_2$ gas and $H_2S$ gas.