Properties of Mica Tape

VPI Mica Tape

• A VPI mica tape, short for vacuum pressure impregnation, comes from muscovite or phlogopite. Both materials provide fire-resistant and high-temperature covering for circuits, furnaces, heaters, boilers and other metal or electrical equipment with highly volatile surfaces. As a dielectric, or insulator, mica tape supports an electrostatic field and neutralizes minimal energy in the form of heat. As a material for tape, mica separates into thin sheets that are chemically inert, flexible and resilient to extreme conditions, such as exposure to light or moisture.

Muscovite

• Most mica tapes in the electrical industry use muscovite. Muscovite tape works in capacitors, suitable for high frequency and radio frequency work. In both sheet and ground form, muscovite provides a high dielectric strength, high tensile strength and resistance to heat, radiation and alkali. High tensile strength simply means that mica tape resists tearing in highly volatile conditions. In this case, muscovite possesses flexibility properties that give the mineral such tensile strength. Muscovite tape also has a nontoxic quality at high temperatures, which makes it suitable for use around humans. Calcined muscovite tape provides an even higher resistance to heat, up to 950 degrees Celsius.

Phlogopite

• In its physical form, phlogopite is a pale brown to brown mineral with elastic and flake properties. Like muscovite mica tape, phlogopite works as an insulator and heat resistor. However, phlogopite holds a higher resistance to heat, remaining stable at up to 900 degrees Celsius. Electrical equipment requires the heat resistance and flexible properties of phlogopite to neutralize energy and sustain the machine's function during long processes that create extremely hot temperatures.

Synthetic Mica Tape

• Unlike muscovite and phlogopite mica paper, synthetic mica paper tape retains insulation properties at 1,000 degrees Celsius. Manufacturing and electrical industries may choose synthetic because of its ability to withstand high heat and provide the same nontoxic, fire-resistant qualities as muscovite and phlogopite. Synthetic also maintains the flexibility and high tensile strength of muscovite and phlogopite mica tapes.