The effect over capacitance properties of surfactants used in Mn(NO ₃)₂ impregnation process in high charge tantalum powders

The manganese dioxide has been used since several years ago like a counter electrode in the tantalum capacitor fabrication. It has been reported that the additions of surfactants reduce the interfacial tension (liquid/solid interface) and help to improve the impregnation process. The impregnation with a non-ionic surfactant in tantalum pellets made from high CV powders was investigated at 30-60°C and concentrations of 0,01-0,1% wt. The influence of the surfactant in the MnO₂ coverage was electrically characterized and the surfactant influences in the pyrolysis condition was analyzed with Differential Thermal Analysis and Scanning Electron Microscopy. A recovery in capacitance (∼10%) was detected for under treatment part types with 100 and 320 μF. The surfactant concentration into the solution is the main factor for the capacitance recovery and the electrical performance. The best capacitance recovery and electrical performance was obtained with 0.05% wt. of surfactant.