Study on dielectric materials of the low temperature co-fired ceramic

• Main Authors: Tui-ting Tu, 涂瑞庭
• Other Authors: Yung-Hui Shih
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/35346761560732185889

碩士 === 義守大學 === 材料科學與工程學系碩士班 === 93 === In order to develop the thick film dielectric materials on the low temperature co-fired ceramic substrate, the effects of B2O3 - SiO2- CaO - Al2O3 (BSCA) glass and lithium fluoride (LiF) addition on the sintering behavior and the dielectric properties of BaTiO3 (BT) were investigated. And finding the best composition and sintering condition of the BaTiO3. In the present study, two liquid-phase sintering aids, BSCA glass and LiF were added into barium titanate to reduce its sintering temperature. The densification rate and dielectric properties of barium titanate was significantly enhanced as the sintering temperature was raised above 745℃, the melting point of BSCA glass. The relative density is reduced by the increasing addition of the BSCA glass, but the addition of 30 wt% BSCA glass in the BT ceramic obtained the worst relative density(＜70%). The relative density is enhanced by the addition of the LiF in the BT ceramic. The addition of the BSCA glass could lower the sintering temperature of BaTiO3. However, the BSCA glass reacted with BaTiO3 to form BaTiSiO5, Ba2TiSi2O8, and Ba2Al2B8O17. The dielectric constant of the reaction phases was low so that dielectric property of sintered BaTiO3 was thus degraded. The addition of 10 wt% BSCA glass in the BT ceramic obtained the best dielectric constant is about 401 when sintered at 1000℃. Because of the the addition of LiF can inhibit lower dielectric constant reaction phases and reduse the Curie temperature, the dielectric constant is enhanced by the increasing addition of the LiF. The Q value is enhanced by the increasing addition of the BSCA glass at the temperature below 900℃, the addition of 30 wt% BSCA glass in the BT ceramic obtained the best Q value is about 527. The Q value is enhanced by the addition of the LiF when sintered at 850℃, the addition of 30 wt% BSCA glass and 1 wt% LiF in the BT ceramic obtained the best Q value is about 690.But the Q value is reduced by the increasing addition of the LiF as the sintering temperature was raised above 900℃. The relative density, dielectric constant and Q value is reduced by the increasing addition of the B2O3 , because there was too many voids in the sample so that dielectric properties of sintered BaTiO3 was thus degraded.