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Daily Electronics Knowledge Lesson 42- Mica and PTFE Capacitors

  Mica and PTFE capacitors are non-polarised capacitive dielectrics for electronic equipment, typically used in applications requiring high stability and reliability. They consist of two metal foils (usually stainless steel or tinned aluminium) and a layer of insulating material made of Mica and PTFE (polytetrafluoroethylene).


Principle of operation: When two metal foils are separated by a layer of Mica and PTFE, an electric field is formed between them. When a voltage is applied, free electrons move under the action of the electric field, filling the difference in ion concentration in the dielectric and forming an electric current. Over time, the ion concentration will stabilise, forming a stable capacitor.



1. Durability: these capacitors have excellent durability due to the excellent chemical resistance, high temperature resistance and electrical properties of Mica and PTFE.

2. High dielectric constant: Due to the high dielectric constant of Mica and PTFE, they provide high capacitance and are suitable for use in applications requiring high energy storage.

3. Reliability: due to their consistent performance and excellent reliability, these capacitors are widely used in many demanding applications.




1. Higher cost: Mica and PTFE capacitors are usually more expensive than other types of capacitors and therefore may not be suitable in some low cost applications.

2. Large size: Due to the physical properties of Mica and PTFE, these capacitors are typically larger than other types of capacitors.


Common Pairings: Mica and PTFE capacitors are commonly used with power filters, power converters, high frequency signal processing, and other applications that require high stability and high reliability.


Common Industries: Mica and PTFE capacitors are widely used in automotive, aerospace, military, industrial equipment, telecommunication, data storage devices and power conversion.


In summary, Mica and PTFE capacitors are high-performance non-polarised capacitive dielectrics with excellent durability, high energy storage capacity and stability for use in applications requiring high reliability and stability. However, they may not be suitable for all application scenarios due to factors such as cost and large size.