Preparation of ultra-thin,high-capacity etched foil-based tantalum anode capacitors
Embedded capacitor technology offers tremendous advantages in reducing device size,lowering power consumption and improving performance.However,current commercial available capacitors suffer from low capacitance density,high thickness,high cost or incompatibility with PCB manufacturing.In order to solve the above problems,this paper proposed a preparation process for ultra-thin high-capacity etched foil tantalum anode capacitors.Electrochemical etching of tantalum foil was carried out using pulsed DC as the current source,which substantially enhanced the specific surface area of the tantalum foil,and the specific capacitance of the anodized tantalum foil at 10 V could reach up to 550 nF/mm2.Meanwhile,high-quality tantalum anodic oxide film growth was carried out with etched tantalum foil as the substrate,and the leakage current density of the prepared tantalum oxide film was only 24 nA/cm2 at 9 V.The solid polymer cathode was formed by impregnating the solid tantalum capacitor in an aqueous dispersion of PEDOT:PSS for several times,and the thickness of the prepared solid tantalum capacitor was less than 50 μm and exhibited excellent frequency characteristics.Its ESR(100 kHz)is as low to 19.2 mΩ,which is about 1/5 of that of Panasonic polymer tantalum capacitor(Panasonic polymer TC),and its capacitance retention in the frequency range of 1～100 kHz is up to 75.5%,which is an improvement of more than 55%compared with Panasonic polymer TC.Foil tantalum electrolytic capacitors based on electrochemical etching will further promote the development of miniaturization and thinness of tantalum electrolytic capacitors,and open up a new idea for embedded capacitor technology.
embedded capacitorstantalum electrolytic capacitorselectrochemical etchingultra-thinhigh capacitance density
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