Within the family of electrostatic polymer film capacitors, specially stacked or "multilayer polymer" types offer the highest power density and dv/dt pulse ratings. The original stacked film capacitors were developed for lower voltage applications and RFI suppression where good high frequency characteristics were required for noise attenuation. The trend over the last ten years has been to higher voltage systems to fill a technology gap wherein ceramic and tantalum capacitors are either not stable or reliable under application stresses. The demand for surface mount devices has fostered the multilayer polymer over conventional, wound film styles which are too heat sensitive or physically large for board mounting applications. Today chip and lead framed chip type multilayer polymer capacitors based upon an innovative technology are available from 25 to 500+ volts. Power train designers must calculate the parasitic losses of filter components to determine their real world ESR and ESL contribution. It is important to understand the stability of the filter components over the application parameters and use components that can be reliable under stresses such as the prescribed base plate temperature and peak voltage. ITW Paktron has introduced a series of multilayer polymer capacitors intended for high frequency current handling at relatively high voltage. Because of the polymer dielectric system used, the devices are stable under various combinations of voltages and power levels and have proven reliable in power train filtering and bypass applications.
展开▼
