Suntan mica for mica capacitor
Natural mica has to be carefully selected because some samples do contain impurities including, iron, sodium, ferric oxide, and lithium. This introduces some variability into any mica that might be used for capacitor manufacture and therefore it must be carefully inspected and classified. This is one of the reasons why silver mica capacitors are more expensive than other types which have less manual intervention.
Mica is chemically very stable and chemically inert. Mica does not react with oil, water, many acids alkalis, and solvents. As a result of this, ageing does not occur to any major degree, and the variations of water vapour in the atmosphere do not cause undue variations in the overall capacitor performance.
Although more costly than other dielectrics, mica is an ideal form of dielectric for very high performance capacitors such as silver mica capacitors.
