AVX has launched the 0402 TACmicrochip series tantalum chip capacitors which it claims is the smallest tantalum device and also offers the highest volumetric efficiency, being capable of delivering 0.47 to 10_F. Key to the capacitance rating of the TACmicrochip capacitors is the construction of these devices which borrows from semiconductor processing.
Traditional moulded tantalum devices are based on a leadframe which result in proportionally larger space waste as the size of the chip decreases. AVX's TACmicrochip are produced from a tantalum capacitor wafer which is then diced into the required chip size, resulting in less wasted space and higher capacitance values.
The 0402 tantalum chips are lead free and feature soft terminations which avoid any cracking if a PCB flexes — a problem which especially affects ceramic devices. As with all tantalum devices these capacitors are not subject to piezo effects. One of the key benefits of tantalum technology is capacitance stability over temperature. Whereas with ceramic products you might expect to half the capacitance across the temperature range due to the high K dielectrics used, the 0402 devices have a stable capacitance range from -55 to +125degC.