Mica has been used because of the following reasons.
- Thermal insulation – Mica has excellent thermal insulation properties. Due to which, heat transfer to copper conductor has been reduced, thereby reducing the chances of softening of copper.
- Fire resistance – Mica has a high melting point of over 1000°C, thereby preventing risk of fire.
- Low thermal expansion – it has very less thermal expansion. So it remains stable under severe temperature.
- Dielectric strength – Mica has high dielectric strength approx. 10 times than PVC.