Applications requiring the superior reliability and performance of Mica Paper

Mica Paper is a premium dielectric material made from Muscovite Mica (a) a mineral. The manufacturers of mica paper process the Muscovite Mica by removing all soluble contaminants from the mica. The resultant flakes are then combined with purified water to produce a slurry that is run through special paper making machines. The slurry is then processed, producing a continuous sheet of uniform thickness (b). The “paper like” structure is maintained by the natural molecular cohesive forces characteristic of natural mica itself and does not contain any binders, adhesives or coloring agents. It is essentially free of any foreign substance that will adversely affect its performance.

In combination with refined aluminum foil as the conductors, or electrodes (c), the mica paper dielectric is then capable of being wound on conventional capacitor winding machines. To provide a means of termination, flag tabs are inserted during the winding process, or the foils may be extended and metalized, depending on the application.

Capacitors constructed with mica paper offer unique characteristics that make them suitable for many applications:

• Low dissipation factor over a wide temperature range. Dissipation factor is a measure of the energy lost in orienting molecules while charging a capacitor. The higher the operating frequency the greater the energy loss. The lower the dissipation factor the higher the electrical efficiency (see data sheets for specific values).

• Nearly constant capacitance over a wide temperature range compared to other popular film, paper-film and ceramic type dielectric capacitors. Especially important in applications employing tuned circuitry (see data sheets for specific values).

• Excellent resistance to corona deterioration. Mica paper is well known for its ability to resist the effects of partial discharge. Mica paper very closely approximates the characteristics of mica splittings in this respect. In applications where corona, or partial discharge is generated, mica paper capacitors offer excellent reliability (fig. 1).

• Excellent resistance to radiation attack, making mica paper capacitors well suited for use in nuclear, space and other applications where there is exposure to gamma rays,
  x-rays and neutrons.

• Good insulation resistance over a wide temperature range. Mica paper capacitors are ideal for circuit applications that require extremely low leakage.

• High energy storage per unit volume. At voltages in excess of 1.0 KV, energy densities of 0.50 - 1.50 joules per cubic inch are common. Higher energy density means that a smaller capacitor which delivers the excellent characteristics of mica paper, can be used.

High reliability resulting from a combination of the characteristics listed above. The ability of mica paper capacitors to operate at high temperatures and high voltage stresses for extended periods of time make mica paper capacitors particularly suited for applications including, but not limited to:

- Ignition systems
- Laser supplies
- Power transmission
- High voltage TWT power supplies
- Oil and gas exploration
- High voltage transmitters
- Radar systems
- High voltage filters
- Nuclear equipment
- Space craft
- High voltage modules
- Medical equipment

 Click here for typical performance specifications for reconstitured mica paper capactors.

Throughout the design and manufacturing process, Chenelec’s engineers and technicians gain a complete understanding of the customer requirements in order to properly design a capacitor with the most reliable materials, and deliver the highest standards of process and quality control. Each capacitor section and assembly must pass all standard electrical tests which include: dielectric withstand voltage, capacitance and dissipation factor. Other electrical tests performed on a sampling, or percent of lot size basis, include: partial discharge, burn-in, impulse and insulation resistance. Physical and environmental testing are conducted in accordance with customer requirements and can include: thermal shock, thermal extreme, physical shock, solderability, terminal strength and vibration.

If high reliability under high voltage and temperature stress conditions are what you need in a capacitor application, give us a call. Our sales staff welcomes all requests whether you need one or one thousand pieces. Our engineering group will work with your requirements to provide samples for engineering approval.