丝网印刷B-Li玻璃掺杂Ba_(0.5)Sr_(0.5)TiO_3厚膜介电性能研究

Screen printing B-Li glass doped Ba_(0.5)Sr_(0.5)TiO_3 thick film and its dielectric properties

钛酸锶钡(BST)陶瓷材料在外置偏压直流电场作用下,具有高的介电可调性,可以广泛地应用于电可调陶瓷电容器以及无源可调微波器件的设计与开发。通过B-Li玻璃的有效掺杂,实现BST陶瓷材料与Ag、Cu贱金属电极材料的低温友好烧结,是发展混合集成厚膜电路的技术要求。主要采用丝网印刷工艺,在Al2O3陶瓷衬底上,制备了B-Li玻璃掺杂的Ba0.5Sr0.5TiO3厚膜材料,并对其最佳烧结温度、物相结构、显微形貌以及介电性能进行了研究。结果表明,B-Li玻璃掺杂的Ba0.5Sr0.5TiO3厚膜材料在950℃可以实现低温烧结,得到了厚度为20μm的均匀致密厚膜材料;相比于BST陶瓷块体材料,5%(质量分数)B-Li玻璃掺杂BST厚膜的居里峰发生了明显的弥散和宽化,介电常数显著降低;在室温和10kHz频率下,其介电常数为210,介电损耗为0.0037,介电可调性可达15%以上,可以适用于厚膜混合集成电路与可调器件的设计和开发。

（Ba, Sr）TiO3 （BST） ceramic materials have a high tunability under a DC electric voltage,which can be widely used in designs and applications of eletro-tunable ceramic capacitors and passive tunable microwave devices. Through the effective doping of B-Li glass, to achieve a low temperature friendly co-fire between BST materials and Ag, cu, etc base metals,is a technical requirement of developing mixed thick-film integrate circuit. In this paper,based on screen printing technology,we prepared a B-Li glass doped Ba0.5 Sr0.5 TiO3 thick film on Al2O3 substrate. The optimal sintering temperature,microstructures and dielectric tunable properties have been investigated. Results indicate that,B-Li glass doped Ba0.5 Sr0.5 TiOa thick film can be sintered as a low temperature of 950℃; the film is 20μm thick and uniformly dense. Compared with BST bulk ceramics, the peak of ferroelectric-paraelectric phase transition of 5wt% B-Li doped BST thick film is suppressed and broadened. The dielectric constant is obviously decreased. At 10kHz and room temperature, the dielectric constant is 210 and the dielectric loss is 0.0037,the tunability can be more than 15 % ,all of which indicate that the material can be applied in thick-film integrate circuit and tunable devices.