- 學位論文
燒結製程對卑金屬X7R積層陶瓷電容器特性之影響
Effects of Sintering Process on the Dielectric Property of BME-X7R-MLCCs
摘要
積層陶瓷電容(MLCCs)是廣為應用在電子產品上的重要電子元件，其中符合EIA標準中的X7R特性(-55~+125℃，△C/C≦±15%)的介電材料，因為其溫度對電容變化穩定之特性，及高介電常數等性質，而被受到重視。現行積層陶瓷電容(MLCCs)多以卑金屬製程，其內電極以金屬鎳為主，但鎳容易氧化而造成電性的不穩定，所以製程之燒除、燒結與再氧化三階段，受到普遍的關注與討論。 本研究將市售X7R介電陶瓷粉末與市售鎳電極膏，製備Disk、MLCC30、MLCC120等不同介電層厚度之試片，以不同的燒除、燒結與再氧化條件進行製備。以阿基米德法分析其燒結密度變化，以XRD進行相鑑定分析，以DTA、TGA、Dilatometer等試驗進行熱分析，以SEM觀察其微結構變化，以HP-4284A LCR meter量測其溫度對電容之變化率及介電損耗。 本研究結果，燒結溫度增加或持溫時間過長與不足，皆會造成其介電損耗增加與電容變化率不穩定；而再氧化溫度不夠或持溫時間不足等，也會造成其介電損耗增加與電容變化率不穩定；另外在不同介電層厚度之MLCC，其電性往厚度越薄之方向順時鐘旋轉。在SEM微結構中，皆有二次相氧化鎂產生，而且透過化學腐蝕，可觀察到化學組成不均勻之核殼結構存在。另外透過XRD與Raman分析，可用來觀察氧分壓之改變，對鈦酸鋇晶格結構之影響。
並列摘要
Multi-Layer Ceramic Capacitors (MLCCs) are widely applied on the electronic products of the important electronic component and can conforme to X7R characteristic of the EIA standard (-55~125 oC，ΔC/C≦±15%). On account of its temperature dependency of capacitance stabilizes, and high dielectric constant properties is highly respected. At present, MLCC is made from the process of Base-Metal-Electrode with Ni electrode but Ni is easy to be oxidized and lead to unstable electrical property. Therefore, the process of burn out, sintering and annealing are widely attention-attrocted and dissussed. In this study, the insufficiency of sintering time, the increase of sintering temperature, and the inadequate of annealing temperature or annealing time cause unstable of tanδ and TCC. The TCCs rotate clockwise as the active thickness in MLCCs is reduced. For SEM analysis, all the microstructure all have second phase of MgO and core-shell structure. By XRD and Raman analysis, we can observe effects of different oxygen partial pressure on the lattice structure barium titanate.