G-7 (GLASS CLOTH / SILICONE RESIN)

G-7 (GLASS CLOTH / SILICONE RESIN)

Material Information

Phenolics are thermoset resins formed by the polymerization of phenol and formaldehyde, which can then be impregnated with cotton canvas or linen, paper, or glass cloth materials to form industrial laminates. Overall, industrial laminates are dense, strong and durable, moisture resistant, lightweight, and will not soften when heat is reapplied. Typically they have high mechanical and insulating properties.

G-7 is made up of a mixture of silicone resin and glass cloth. G-7 has excellent heat and arc resistance, is self-extinguishing, and has good electrical properties in wet conditions that are even better under dry conditions. It is also the most temperature resistant grade. Although it is not stronger than epoxies and industrial thermosets at lower temperatures, it is stronger at temperatures over 400ºF. These properties make G-7 ideal for use in electrical grade insulation, heating insulation and appliance insulation. G-7 is available in sheet, rod, and tube.

G-7 meets MIL-I-24768/17 TYPE GSG

Application

  • High temperature electrical applications
  • High heat insulators
  • Gaskets
  • Armature barriers
  • Mechanical insulators

Properties

  • Good wet electrical properties, excellent dry electrical properties
  • Excellent heat and arc resistance
  • Self-extinguishing
  • Desnse and structurally strong
  • Lightweight
  • Doesn’t soften under reapplication of heat

Typical Properties of Glass Phenolics (Sheet Form)

Physical

Astm Test Method

G-5/G-9

G-7

G-10/FR-4

G-11

Density (lb/in^3) D792 0.067 0.065 0.065 0.065
Specific Gravity D792 1.85 1.8 1.8 1.8
Water Absorption @ 24 hours (%) D570 0.6 0.1 0.1 0.2

Mechanical

Tensile Strength (PSI) Lengthwise, Crosswise D638 61,600 and 51,100 20,000 and - 45,000 and 38,000 43,000 and 37,000
Flexural Strength (PSI) Lengthwise, Crosswise D790 61,600 and 51,100 30000 and - 75,000 and 65,000 80,000 and 70,000
Compressive Strength (PSI) D695 65,000 50,000 65,000 63,000
Flexural Modulus (KPSI) Lengthwise, Crosswise D790 2,000 and 1,700 1,600 and - 2,700 and 2,400 3,000 and 2,700
Izod Impact (Notched), ft-lb/in Lengthwise, Crosswise D256 12.5 and 8.5 13.0 and - 14.0 and 12.0 12.0 and 9.0
Rockwell Hardness D785 M115 M105 M110 M112

Thermal

Coefficient of Thermal Expansion,
10^-5/°F Lengthwise, Crosswise
D696 .83 and 1.00 .72 and .90 .55 and .66 .72 and .83
Continous Service Temp (Operating), °F 285 430 284 329
Thermal Conductivity, BTU-in/hr-ft² °F C177 2 2 2 2
Flammability Rating UL94 VO VO VO HB

Electrical

Dielectric Strength, Short Term,
(Volts/Mil) @ .125″ Thick
D149 300 350 800 900
Arc Resistance (sec) D495 180 240 100 120
Dielectric Constant at 1 MHz D150 6.3 4.5 5 4.5
Dissipation Factor at 1 MHz D150 0.019 0.018 0.019 0.02

NOTE:

The information contained herein are typical values intended for reference and comparison purposes only. They should NOT be used as a basis for design specifications or quality control. Contact us for manufacturers' complete material property datasheets. All values at 73°F (23°C) unless otherwise noted.