• Title, Summary, Keyword: Dielectric material

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Preparation and Dielectric Behavior of D-Glass with Different Boron Contents (보론함량에 따른 D-glass의 유전율 특성)

  • Jeong, Bora;Lee, Ji-Sun;Lee, MiJai;Lim, Tae-Young;Lee, Youngjin;Jeon, Dae-Woo;Shin, Dongwook;Kim, Jin-Ho
    • Korean Journal of Materials Research
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    • v.27 no.1
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    • pp.39-42
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    • 2017
  • E-glass (electrical glass) fiber is the widely used as a reinforced composite material of PCBs (printed circuit boards). However, E-glass fiber is not stable because it has a dielectric constant of 6~7. On the other hand, D-glass (dielectric glass) fiber has a low dielectric constant of 3~4.5. Thus, it is adaptable for use as a reinforcing material of PCBs. In this study, we fabricated D-glass compositions with low dielectric constant, and measured the electrical and optical properties. In the glass composition, the boron content was changed from 9 to 31 wt%. To confirm the dependence of the dielectric constant on melting properties, D-glass with 22 wt% boron was melted at $1550^{\circ}C$ and $1650^{\circ}C$ for 2hrs. The glass melted at $1650^{\circ}C$ had a lower dielectric constant than the glass melted at $1550^{\circ}C$. Therefore, the D-glass with boron of 9~31 wt% was fabricated by melting at $1650^{\circ}C$ for 2hrs, and transparent clear glass was obtained. We identified the non-crystalline nature of the glass using an XRD (x-ray diffractometer) graph. The visible light transmittance values depending on the boron contents were measured and found to be 88.6 % ~ 82.5 %. Finally, the dielectric constant of the D-glass with 31 wt% boron was found to have decreased from 4.18 to 3.93.

Effects of Fluoride Additions on Sintering and Microwave Dielectric Properties of CaWO$_4$ (Fluoride 첨가에 따른 CaWO$_4$의 소결 및 고주파 유전특성)

  • 이경호;김용철;방재철
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.127-130
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    • 2002
  • In this study, development of a new LTCC material using a non-glassy system was attempted with respect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. For LTCC application, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them, CaWO$_4$ was tamed out the suitable LTCC material. CaWO$_4$ can be sintered up to 98% of full density at 1200$^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 10.15, 62880GHz, and -27.8ppm/$^{\circ}C$, respectively. In order to modify the dielectric properties and densification temperature, 0.5∼1.5 wt% LiF were added to CaWO$_4$. LiF addition reduced the sintering temperature/time down to 800$^{\circ}C$/10∼30min due to the reactive liquid phase sintering. Dielectric constant lowered from 10.15 to 9.38 and Q x fo increased up to 92000GHz with increasing LiF content.

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The Influence of $Ta_2O_{5}$ Addition on Dielectric Characteristics of Zirconium Titanate Ceramics (Zirconium Titanate 세라믹 유전체에서 $Ta_2O_{5}$ 첨가가 유전특성에 미치는 영향)

  • 이석진;이창화;이상석;최태구
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.129-132
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    • 1992
  • Rutile was among the first dielectric materials used. However, rutile exhibits a very high temperature coefficient of capacitance (about -750[ppm/$^{\circ}C$]) which resticts its practical application. Since this first use of titania, other materials have also been studied with the object of decreasing the temperature dependence whilst retaining favorable dielectric loss, Q, and relative permittivity. The temperature coefficient of temperature compensation capacitor is +100~750[ppm/$^{\circ}C$], dielectric constant 10~150. Low loss ceramics with dielectric constants in the 10~150 range also found application. Recently, their applications are extended in EMI filter and dielectric materials for microwave. There temperature coefficient of dielectric materials approaches 0[ppm/$^{\circ}C$]. The dielectric preperties of zirconia titanate ceramics prepared by addition of $Ta_2O_{5}$ were investigated.

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Can be the dielectric constant of thin films as-grown at room temperature higher than that of its bulk material?

  • Jung, Hyun-June;Kim, Chung-Soo;Lee, Jeong-Yong;Yoon, Soon-Gil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.23-23
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    • 2010
  • The $Bi_2Mg_{2/3}Nb_{4/3}O_7$ (BMNO)-Bi composite films sandwiched by an $Al_2O_3$ protection layer exhibited a linear increase of a dielectric constant with increasing thickness and the 1000nm-thick BMNO-Bi composite films showed a dielectric constant (~220) higher than that of its bulk material (~210), keeping a low leakage current density of about $0.1{\mu}A/cm^2$. An enhancement of the dielectric constant in the BMNO-Bi composite films was attributed to the hybrid model combined by a space charge polarization, dipolar response, and nano-capacitors. On the other hand, 1000nm-thick BMNO-Bi composite films sandwiched by 40nm-thick BMNO layer exhibited a dielectric constant of about 450 at 100 kHz and a leakage current density of $0.1{\mu}A/cm^2$ at 6V.

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Microwave Properties of Organic-inorganic Composite Material Antenna with Various Fabrication Method of Conduction Material (전도체 형성 방법에 따른 유무기 복합재료 안테나의 고주파 특성)

  • Park, Sang-Hoon;Seong, Won-Mo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.9
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    • pp.832-837
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    • 2006
  • Antennas were fabricated by physical(adhesive) and chemical(deposition+plating) method on organic-inorganic composite material. And antennas were measured dielectric constant and gain. Dielectric constant of antennas were fabricated by physical method was decreased with increase of adhesive tape thickness and number of conduction material composition. But antennas were fabricated by chemical method was reached to 90 % of dielectric material. Gain of antennas were fabricated by physical method was decreased with increase of adhesive tape thickness. But they were unrelated with conduction material composition. The other side antennas were fabricated by chemical method excelled more 0.8 dBic than antennas were fabricated by physical method in gain of antenna. Finally, chemical method can expect excellent product process because it can produce smaller size, higher gain and elimination of many handworks.

Design Method of Tunable Pixel with Phase-Change Material for Diffractive Optical Elements

  • Lee, Seung-Yeol;Kim, Han Na;Kim, Yong Hae;Kim, Tae-Youb;Cho, Seong-Mok;Kang, Han Byeol;Hwang, Chi-Sun
    • ETRI Journal
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    • v.39 no.3
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    • pp.390-397
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    • 2017
  • In this paper, we propose a scheme for designing a tunable pixel layer based on a $Ge_2Sb_2Te_5$ (GST) alloy thin film. We show that the phase change of GST can significantly affect the reflection characteristic when the GST film is embedded into a dielectric encapsulation layer. We investigate the appropriate positions of the GST film within the dielectric layer for high diffraction efficiency, and we prove that they are antinodes of Fabry-Perot resonance inside the dielectric layer. Using the proposed scheme, we can increase the diffraction efficiency by about ten times compared to a bare GST film pixel, and 80 times for the first-to-zeroth-order diffraction power ratio. We show that the proposed scheme can be designed alternatively for a broadband or wavelength-selective type by tuning the dielectric thickness, and we discuss a multi-phase example with a double-stack structure.

Dielectric Properties of Amorphous and Composite Alkoxi-derived Alumina Thin Films

  • N., Korobova;Soh, Dea-Wha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.772-775
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    • 2003
  • The development of new improved type of dielectric materials on the conception of multiphase structure has been carried out in this paper. Metal alkoxides solutions were used for application of thin film by electrophoretic deposition technique. We succeeded in preparation of amorphous and composite dielectric films from Al alkoxides. Specific features of the preparation technique were considered. Microstructure of the films was examined as well as their dielectric properties. TEM analyses reveals that films deposited from aging sols and heat-treated at temperatures as low as $400^{\circ}C$ contain small whiskers of ${\delta}-Al_2O_3$.

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A Study on Dielectric Properties of Printed Circuit Board Materials with Variation of Frequency and Temperature (온도 및 주파수 변화에 따른 프린트 배선기판의 유전특성 연구)

  • 박종성;김종헌;이준웅
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.773-777
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    • 1998
  • This paper presents the results of measured permittivity of PCB sheet material in the frequency range of 0.1 ~ 2[㎓] and temperature range of 25~ 85[>$^{\circ}C$]. Microstrip lines with different physical length are implemented to measure the attenuation and phase shift of the signals through these lines. The loss factor of glass-epoxy and teflon could by calculated with the measured dielectric constant and the attenuation. From the experiment, the glass-epoxy was more influenced by temperature and frequency than teflon. The average dielectric constants of glass-epoxy and teflon within the measured frequency range are 4.48 and 2.18, respectively.

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