A study conducted by David Liu and Michael Sampson of the NASA Goddard Space Flight Center on the performance of conductive polymer aluminum electrolytic capacitors has revealed that the physical construction parameters play an important role in the performance of the finished capacitor. Mr. Liu and Mr. Sampson conducted an internal NASA study that tested various types of polymer aluminum (PA) capacitors from various manufacturers with various combinations of capacitance, rated voltage and ESR were physically and electrically compared.
Three different types of PAcapacitor constructions were compared- traditional wound construction; stacked construction and laminated construction. The study revealed that while all three constructions demonstrated high capacitance and low ESR at rated voltage; that the PA capacitors with laminated structure exhibited the most stable dielectric response versus frequency and temperature. The laminated PA adapts a unique structure that differs from loose wound (vertical chip) and stacked chip (Horizontal Chip) constructions. The anodized aluminum foil employed in the laminated chip is noted as being thick (30 μm), and the etched tunnel depth is about 13 μm on each side of the aluminum foil; with the foil only “selectively”etched. The non-etched side of the aluminum foil was wire-bonded directly to the lead frame for the formation of the anode.
The cathode was formed using a nickel coated copper plate that wassandwiched between the two anodized aluminum foil anodes (Editor’s Note: This story is derived from a technical paper delivered at the
Capacitor & Resistor Technology Symposium held on March 16 2010 in New Orleans, LA USA).