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 0.55
Apparent density kg/m3 2.4 × 103 2.4 × 103
Dielectric breakdown strength wt% 46 40
Insulation resistance Normal state 2000 or more 2000 or more
Surface resistivity Ω 1 × 1012 or more 1 × 1012 or more
Dielectric constant 60Hz F/m 5 to 7 5 to 7
1MHz 5 to 7 5 to 7
Dielectric tangent 60Hz % 0.3 to 0.5 0.3 to 0.5
1MHz 0.6 to 0.8 0.6 to 0.8
Flexural strength MPa 372 to 402 372 to 402
Elastic modulus in bending
Thermal conductivity W/m·K
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.