Described is a capacitor assembly that is thermally and mechanically stable under extreme conditions. Thermal stability is provided by enclosing and hermetically sealing the capacitor element within a housing in the presence of a gaseous atmosphere that contains an inert gas, thereby limiting the amount of oxygen and moisture supplied to the solid electrolyte of the capacitor. To provide good mechanical stability, the assembly contains at least one external termination (e.g., anode and/or cathode termination) extending beyond an outer periphery of a surface of the housing. The degree to which the external termination extends beyond the outer periphery relative to the dimension of the housing is selectively controlled to increase the surface area available for soldering to a circuit board.