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-10 is made up of a mixture of epoxy resin and glass cloth. G-10 has extremely high mechanical strength and dimensional stability over temperature, low water absorption, and superior electrical properties when both wet and dry. These electrical properties make it the most widely used in the electrical field. G-10’s properties are exhibited over a wide range of temperatures and humidities. G-10 is stronger than the other glass-epoxy laminate G-11, but is not as good of an insulator and can’t handle quite as high of temperatures. Because of it’s strength, G-10 is difficult to machine and may require special equipment. G-10/FR-4 is available in sheet, rod, and tube.

FR-4 is a fire retardant grade of G-10.

G-10 Phenolic meets MIL-I-24768/2 TYPE GEE.
FR-4 Phenolic meets MIL-I-24768/27 TYPE GEE-F.


  • Terminal boards
  • Washers
  • Sleeves
  • Structural components
  • Parts where size to weight ratio is critical
  • Electrical test equipment
  • Electric rotor insulation
  • Circuit boards


  • Dimensional stability
  • Mechanical strength
  • Good insulator
  • Low water absorption
  • Stable properties over wide range of temperatures and humidities
  • Superior electrical properties in wet and dry conditions
  • Fire retardant (FR-4)

Typical Properties of Glass Phenolics (Sheet Form)


Astm Test Method





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


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


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


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


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.