电化学蚀刻钽箔制备高容量薄膜钽电解电容器

High-Capacitance Thin Film Tantalum Electrolytic Capacitor Fabricated from Electrochemically Etched Tantalum Foils

钽电解电容器具有较高的电容密度和较好的稳定性,将钽电解电容器制作成埋入式电容能够扩展钽电容的应用。传统钽电容经钽粉压块、烧结、被膜等工艺制作而成,其具有较大的尺寸而不能被埋入到电路板或者基板内部。该研究探索了电化学蚀刻钽箔的方法来制作钽电解电容阳极并进一步制作成片状埋入式钽电解电容器。在0.1 mol/L稀硫酸水溶液中测试经蚀刻并氧化后的钽箔阳极,得到最大比电容为74 nF/mm^(2)。将该钽箔阳极制备成钽电解电容器件,测试结果显示电容器件在100 Hz~1 MHz的电容值>30 nF/mm^(2);持续施加10 V直流电压1200 s,其漏电流最大为2.7×10^(-6)A,薄膜电容的总厚度约为75μm。

The use of Tantalum(Ta)electrolytic capacitors as embedded components constitutes a promising strategy to extend the application of embedded capacitors,because Ta electrolytic capacitor can provide both high capacitance and excellent stability.However,the huge thickness of conventional Ta electrolytic capacitor makes it hard to be embedded in a printed circuit board or substrate.In this work,we propose to employ the electrochemical etching of thin Ta foils to fabricate the anode of Ta electrolytic capacitors for embedded application.The specific capacitance of electrochemically etched Ta anode reaches as high as 74 nF/mm^(2)when measured in 0.1 mol/L H2SO4.The etched Ta anode is then fabricated into electrolytic capacitors,and a stable capacitance of>30 nF/mm^(2)is demonstrated in the frequency range from 100 Hz to 1 MHz and a low leakage current of 2.7×10^(-6)A for a duration of 1200 seconds at a direct voltage(DC)of 10 V.The whole thickness of the capacitor is decreased to~75μm.