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Polymer Hermetic Seal (PHS) Series FAQ

How does the PHS differ from wet tantalums?

Both technologies use tantalum anodes with a tantalum pentoxide dielectric produced by electro chemical processes. The difference is the cathode system. The PHS utilizes conductive polymer. This cathode system offers significant performance improvements (frequency response, temperature, failure mode, etc.) versus wet tantalums.

Why is the PHS up to 25% lighter than an equivalent wet tantalum?

The PHS is lighter due to the materials set, especially the can construction (tantalum vs. brass).

Why does the capacitance not roll off at frequency and temperature as compared to a wet tantalums?

The stability of the capacitance is significantly improved at frequency and low temperature, and is due to the extremely low demonstrated ESR of the PHS.

How can the PHS handle more ripple current than the wet tantalum?

The use of polymer technology as the cathode system and the resulting extremely low Equivalence Series Resistance (ESR) results in less internal heating due to ripple current resulting in higher ripple current capability.

Are these products approved as per MIL-PRF?

Currently, PHS products are qualified according to KEMET's Internal Qualification Plan and the T550 PHS Series meets all the requirements of DLA Drawing 13030. Future plans include developing and qualifying the T550 PHS Series to a MIL-PRF specification.

What is the PHS operating temperature?

The T551 PHS Series offers all of the performance benefits of the T550 series but with an increased temperature rating of 125°C. The T550 PHS Series is rated at 105°C.