低溫燒結玻璃-鈦酸鍶介電陶瓷之研究

Abstract

近年因對於微波應用之材料有更嚴苛之需求，而帶動了低溫共燒陶瓷的發展。在製備低溫共燒陶瓷時，陶瓷基板與電路電極一同燒結至緻密以避免過多的裂隙生成，因此燒結溫度需低於電極之熔點。然而一般而言，陶瓷燒結緻密的溫度皆遠高於電極熔點，因此如何有效降低陶瓷燒結溫度為本研究最主要的目標。此外為符合高傳輸效率及高可靠性的特性，本研究亦以低介電常數及高品質因子作為目標。 本研究於系統中加入玻璃相，以期望能借助其液相燒結的特性以降低陶瓷的燒結溫度。鈦酸鍶作為一介電性質優異的材料已被廣泛的研究，然而其作為低溫共燒陶瓷燒結溫度仍然過高，因此本研究選用玻璃-鈦酸鍶系統進行低溫燒結的研究。並且亦針對富有鍶或者富有鈦的鈦酸鍶與玻璃一同燒結的結果進行研究。 結果顯示，當玻璃含量超過60 wt%時，玻璃-鈦酸鍶系統將會燒結緻密並且連帶提升了品質因子。而富有鍶的鈦酸鍶系統表現出較低的品質因子，原因乃為在高溫下鍶更易與玻璃反應生成二次相。而介電常數則是受到玻璃含量的影響，當玻璃含量越高介電常數亦越低。在微波頻段下量測的Qхf值中，最高的為富有鈦的鈦酸鍶系統，其值為7089 GHz。

Low temperature co-fired ceramics (LTCC) are in rapid development for microwave applications due to its high reliability, low cost and high speed of signal propagating. For the process of LTCC components, the ceramics should sinter with electrodes. Therefore, the sintering temperature should be lower than the melting temperature of electrodes. Lowering the sintering temperature of ceramics is the key for LTCC process. Additionally, the relative permittivity is expected to be as low as possible to meet the requirements of high speed signal propagating; quality factor as high as possible due to the high reliability of LTCC. There are several ways to lower the sintering temperature of ceramics. In the present study, the approach of adding low melting materials is chosen. Glass addition is believed to be the most effective way to lower the sintering temperature of ceramics via liquid phase sintering. Strontium titanate (SrTiO3) has been investigated widely due to its excellent dielectric properties. However, the sintering temperature of SrTiO3 is too high to be used for LTCC. Therefore, glass-SrTiO3 was chosen as ceramics systems to study the microwave properties. In addition, Sr-rich and Ti-rich SrTiO3 sintered with glass was investigated as well. For the systems with glass content higher than 60 wt%, they exhibited higher quality factor. The Q for Sr-rich glass-SrTiO3 systems is low after sintering at high temperature due to the formation of second phases. The relative permittivity for the systems with higher glass content systems is low due to the presence of glass. At microwave frequency, the Qхf value was 7089 GHz for Ti-rich systems.