Shin-Etsu Sepla Film® is a super engineering plastic film . It is a non-stretched film made of PEEK, a super engineering plastic. It is available as either a thick or thin film.


[Industrial field]

Smartphone, Home electric appliances, Automotive Industry, Electrical Products, Medical, Aviation, Pipeline, Semiconductor Materials, Agriculture


It features excellent heat tolerance, sliding properties, and chemical resistance. Its advantages also include its low water absorbing property and low dielectric constant.



  • Diaphragm for speakers and receivers
  • Material for circuit substrates in high-frequency 5G devices 
  • Material for substrates in high-frequency 5G base stations  
  • Impregnation for CFRTP  
  • Material for copper wire coverings  
  • Motor insulation  
  • Exterior material for batteries  
  • Material for medical equipment components  
  • Semiconductor process cover films  
  • Covering material for heaters


  • Melting point: 343℃; glass transition point: 143℃

  • Stable up to 500℃ or the carbonization point

  • Chemical resistance

  • Melt processibility

  • No toxic gas generated even under burning

  • Low water absorbing property (0.05%)

  • Low dielectric constant 3.0  Dielectric tangent 0.003 (1GHz)


  • Non-extend film of amorphous plastics (3-50 μm)

  • Non-extend and high crystallized film of crystallized plastics (6-250 μm)

Shin-Etsu Sepla Film® is a non-stretched film, with a thickness tolerance of ±5%  
6inch Core(Resin-impregnated paper core) 
Width 650mm
Product length depends on thickness.

Dimensions and specifications

Physical properties Table

Test item Unit PEEK resin
Crystalline/non-crystalline - Crystalline
Specific gravity - 1.31
Glass transition point/melting point 146/339
Tensile module Elasticity MD N/mm² 3720
TD 2940
Yield strength MD N/mm² 80
TD 75
Maximum strength MD N/mm² 135
TD 83
Breaking elongation MD % 72
TD 239
Electrical characteristics Dielectric strength kV/mm 16
Dielectric constant - 3.30
Dielectric tangent - 0.003
Water absorbing property (23℃, 24 hours) - 0.1