top of page

High Temperature Mica Capacitors (PTFE)

Custom's made-to-order mica paper capacitors are available for a variety of high temperature / high voltage applications. These types of capacitors can be rated up to 260°C for a variety of applications that include, but are not limited to, down-hole oil and gas exploration and drilling, jet engine ignition systems, etc. This type of high reliability capacitor can be packaged with a variety of materials to meet your high temperature / high voltage requirements. Our mica paper capacitors can be designed to meet most stringent electrical, environmental, and physical requirements. To order your high temperature / high voltage mica paper capacitors, please contact our sales department or visit our directory for a complete listing of our International Sales Representatives.

Configurations available:

  • Single-Section Capacitors

  • Multi-Section Capacitors

  • Multi-Capacitor Assemblies

A variety of high temp mica paper capacitor styles are available using a combination of materials. The following table lists these materials and their associated maximum temperatures.

Temp Range
Capacitor Impregnant
Capacitor Impregnant
Polymide / Fiberglass
Wrap and Fill (Kapton® Tape)

Terminations available:

  • Solid Wire Lead

  • Insulated Wire Lead

  • Turret Terminal

  • Threaded Studs or Inserts

  • PTFE Insulated Wire Lead

  • PTFE, Ceramic, or Glass Insulated Terminals

Mounting available:

  • Threaded Studs or Inserts

  • Plates or Brackets

High voltage applications up to 15 kVdc or 1000 Vrms. 

Units are available in rectangular or tubular designs. Metal housings are available in aluminum, stainless steel or plated brass. 

Meets shock and vibration requirements in drill bit applications. Meets requirements in AC or DC motor applications.

High Temperature Mica Paper Capacitor Performance Specifications:

Capacitance Range:

  • 100 pF to several µF

Capacitance Tolerance:

  • Standard is ± 10 %. Tighter tolerances available

Voltage Range:

  • 1 to 15 kVdc

Dissipation Factor:

  • 0.5 % Max at 25°C, 2.0 % Max at 200°C

Insulation Resistance:

  • 5,000 Megohm·µF Min at 25°C,

  • 5 Megohm·µF Min at 200°C

Temperature Coefficient of Capacitance:

  • + 8 % Max from 25°C to 200°C

  • - 4 % Max from 25°C to -65°C

Dielectric Withstanding Voltage (DWV):

  • Typically 110 % to 200 % of rated voltage for 15 to 60 seconds.

Environmental per MIL-STD-202:

  • Vibration per Method 201 and 204

  • Shock per Method 213

  • Thermal Shock per Method 107, Test Condition B

  • Humidity per Method 103, Test Condition B

  • Moisture Resistance per Method 106, Steps 1 through (Metal or Polyimide Housings Only) Immersion per Method 104, Test Condition B (Metal or polyimide Housings Only)

High Temp PTFE Capacitors

Two types of construction are available:

  • Film/Foil

The dielectric material used in the design and construction of PTFE film capacitors is tetrafluoroethylene (TFE) film. This type of film can be manufactured with several basic processes: casting, extrusion, or skiving (i.e., shaved continuously from the surface of a cylindrical block of molded resin). Casting is the preferred process for the thin, multilaminar TFE film that is used in Custom's lower voltage high temperature capacitor products. The casting process includes deposition of extremely small particles of TFE (i.e., an average diameter of approximately 0.2 µm) from an aqueous suspension to form a continuous thin film on a belt, heating and sintering, and fusing (at temperatures > 370°C). The casting process provides uniform tensile strength and elongation in linear and transverse directions and a smooth surface profile.

PTFE Film/Foil Capacitors Performance Specifications:

Capacitance Range:

Voltage Ratings:

  • 100, 200, 400, 600 Vdc

Dissipation Factor:

  • 0.02 % Max, over temperature range

Insulation Resistance (RT):

  • 50 VDC Rating: 1 x 1011 ohm·µF, but need not to exceed 1011 ohms

  • All other ratings: 1 x 1012 ohm·µF, but need not to exceed 1012 ohms

Insulation Resistance (200°C):

  • All ratings: 1 x 109 ohm·µF, but need not to exceed 109 ohms

Temperature Coefficient of Capacitance:

  • + 1 % to - 3 %, from 25°C to 200°C

Dielectric Withstanding Voltage (DWV):

  • Typically 150 % of rated voltage

Recommended for high frequency applications.

Note: Mylar is registered trademark of the E.I. Dupont Corporation

bottom of page