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) |
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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 |
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| 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 |
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| 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 |
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| 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.