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Molded and Potted

These are reconstituted mica paper capacitors that are used where non-standard shapes, sizes, or mounting configurations are required. A variety of encapsulating epoxies and packaging materials are available depending on unit requirements and the environment in which the capacitors will be used. 

In a potted or tube unit, mica paper capacitors or capacitor assemblies are inserted into a tube or shell, which becomes an integral part of the assembly. Tubes can be made from materials that include aluminum, epoxy impregnated glass cloth, and stainless steel before being subjected to a potting process. In a molded unit, however, mica paper capacitors or assemblies are inserted into a mold and then cast in a potting process. Molded units are preferable where corona discharge is a concern. The potting materials and processes provide more environmental protection for the potted capacitors than the basic "wrap and fill" capacitors, and are generally limited to cylindrical or cuboidal shapes. However, our Molded units can assume practically any shape. For units with multiple components, i.e., resistors, R/C networks, spark gaps, etc., please visit our "Integrated Electronics" page. 

For many years, Custom has designed and built reconstituted mica paper capacitors that are used in many satellite systems where low weight and volume are critical requirements. The embedding material used in these "Strato" capacitors successfully meets the outgassing requirements of the ASTM E595 and NASA's SP-R-0022 specification. 


A variety of terminations and mountings of our Potted and Molded units can be held to tight tolerances. Designed to meet your most stringent electrical, environmental, and physical requirements, our encapuslated Potted and Molded units have an operating temperature range of -65° to 125°C (for special housed units rated to 260°C, see High Temperature Capacitors) and are available in the following configurations:

  • Single-Section Capacitors

  • Multi-Section Capacitors

  • Multi-Capacitor Assemblies

Terminations available:

  • Wire Lead

  • Turret Terminal

  • Threaded Studs or Inserts

  • High Voltage Connectors


Mounting available:

  • Threaded Studs or Inserts

  • Through Bushings

  • Plates

If you have questions concerning our potted or molded capacitors, please contact our sales department or visit our directory for a complete listing of our International Sales Representatives.

Encapsulated Capacitor (Potted, Encapsulated) Performance Specifications

Capacitance Range:

  • 100 pF to several µF

Capacitance Tolerance:

  • Standard is ± 10 %. Tighter tolerances are available.

Voltage Range:

  • 1 to 50 kVdc

Dissipation Factor:

  • 0.5 % Max at 25°C

  • 1 % Max at 125°C

Insulation Resistance:

  • 5,000 Megohm·µF Min at 25°C

  • 25 Megohm·µF Min at 125°C

Temperature Coefficient of Capacitance:

  • + 5 % Max from 25°C to 125°C

  • - 3 % 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

  • Moisture Resistance per Method 106, Steps 1 through 6

  • Humidity per Method 103, Test Condition B

  • Immersion per Method 104, Test Condition B

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

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