C 3.7. SOLID NIOBIUM and NIOBIUM OXIDE CAPACITORS Niobium is a sister metal to tantalum, and shares many chemical characteristics with it, in addition to a few disadvantages and advantages of its own when used as a capacitor dielectric. Niobium capacitor technology has existed for decades, but its limitation in maximum rated voltage, lower volumetric efficiency, incompatibility with low ESR polymer electrode, limited range...
C 3.6 SOLID SINTERED TANTALUMS with MANGANESE DIOXIDE C 3.6.1 Introduction We start with cross section schematics of typical SMD tantalum chip construction. Explanation of tantalum MnO2 capacitor inner structure (not to scale) Figure C3-46a. Tantalum MnO2 capacitors Tantalum SMD chip capacitor structure; source: Kemet The tantalum metal has a dielectric constant of approximately 27. The price for solid tantalums is relatively high due...
C 3.5 SOLID AL ELECTROLYTICS with CONDUCTIVE POLYMER or TCNQ SALT C 3.5.1 Polymer electrolyte Other variant of a solid electrolyte is conductive polymer electrolyte. The aluminum oxide on an etched and formed foil is covered with an electrically very conductive and doped polymer as previously shown in Figure C3-7. The polymer can withstand temperatures up to +105 °C. The ESR of the capacitor...
C 3.4 SOLID ALUMINUM ELECTROLYTICS (SAL) with MANGANESE DIOXIDE (obsolete capacitor technology) The SAL are aluminum electrolytic capacitors with anodic oxidized aluminum oxide as dielectric and with the semiconducting solid manganese dioxide as electrolyte. They are made of etched and formed aluminum anodes, which are folded for the dipped pearl types or wound into a roll for the axial style. The solid manganese dioxide...
C 3.3 WET ALUMINUM ELECTROLYTICS C 3.3.1 Introduction Wet aluminum (Al) electrolytic capacitors continuously generate hydrogen gas under operation, even under a small residual charge. (note: if capacitors are stored voltage-free no hydrogen is being released during storage). That hydrogen must be able to diffuse and exit the package or it will rupture. Thus conventional wet Al electrolytics must not be hermetic sealed. The...
