Panasonic Polymer & Film MLCC Alternatives

With their ultra-low ESR values, polymer capacitors have a low impedance near their resonance point. A lower impedance reduces AC ripple in power circuits. Testing has revealed as much as a fivefold reduction in peak-to-peak voltage changes when comparing polymer capacitors to conventional low-ESR tantalum capacitors.

With ceramic capacitors, capacitance drifts in response to temperature changes and DC bias. Polymer capacitors have no such problem and remain stable over time. This stability is particularly important in industrial and automotive applications, which tend to experience fluctuations in operating temperatures. Hybrid capacitors add another dimension to capacitance stability. They keep a stable capacitance in the face of common operating conditions (high frequencies and low temperatures) that reduce the capacitance of conventional liquid electrolytic capacitors.

Conventional electrolytic capacitors can suffer from safety issues that could cause them to short circuit and fail. Polymer capacitors have a self-healing capability that eliminates this failure mode. The repair takes place in response to the Joule heating that occurs when a dielectric defect triggers a short circuit. The heating breaks the molecular chain of the conductive polymer near the defect, driving up its resistance and effectively forming a barrier against any current leaking from the electrode. In the case of hybrid capacitors, an additional self-healing mechanism comes into play (the liquid electrolyte causes current flow near the defect to reoxidize the aluminum).