High-voltage resistant sheets


The D461 and MCT-BS high-voltage resistant sheets are made by combining mica paper with epoxy resin.
They are also used for bulkhead plates (barrier plates) and rigidity reinforcement boards in high-voltage equipment. They provide excellent electrical insulation even though the board is thin, and is therefore useful for making insulation materials thinner and lighter.
MCT-BS has obtained the UL94 V-0 standard.


  • (1) Excellent in corona resistance, arc resistance and tracking resistance, and also have good high-frequency property.
  • (2) Thanks to excellent workability, cutting, machining, and punching can be done easily.
  • (3) These products are unlikely to warp, and possess high mechanical strength.
  • (4) They have excellent resistance to water.
  • (5) In the field of materials for electrical appliances and electronic devices, they can contribute to weight reduction, flame proofing, and cost reduction.


  • (1) Electrical insulation bulkhead plates in switch boards
  • (2) Shield (barrier) for aerial switches
  • (3) Insulation washers and spacers
  • (4) Heat-resistant insulation reinforcing plates

Composition and standard dimensions

Mica Mica paper based on uncalcined muscovite
Binder Epoxy Flame-retardant epoxy
Standard thickness (mm) 0.20 to 20.00
Width × length (mm) 600 × 1000


Nominal thickness mm 0.55 0.60
Apparent density kg/m3 2.2 × 103 2.3 × 103
Dielectric breakdown strength kV/mm 56 39
Insulation resistance Normal state 2000 or more 2000 or more
Surface resistivity Ω 7 × 1014 3 × 1014
Dielectric constant 60Hz F/m 4.0 4.0
1MHz 3.9 3.8
Dielectric tangent 60Hz % 1.4 1.3
1MHz 0.5 0.4
Flexural strength MPa 418 378
Elastic modulus in bending GPa 55 48
Thermal conductivity W/m·K 0.42 0.33
Arc resistance S 181 182
Comparative tracking index (CTI) V 600 600
Combustibility 94V-1 (t1.0 mm or more) 94V-0
94V-0 (t5.0 mm or more)

*Measured in compliance with JIS C 2116 and JIS K 6911.
*The above values are examples from tests, and are not guaranteed values.