FR-4 and G-10 are the most versatile all-around of the laminate grades and are made by impregnating an epoxy resin binder into continuous glass woven fabric.  G10/FR4 has extremely high mechanical strength, good dielectric loss properties, and good electric strength properties, both wet and dry.  G10/FR4 are widely used in the electronics field – primarily because water absorption is virtually nil, rendering it an excellent insulator.

The difference between G10 and FR4 is that FR4 is a fire-retardant grade of G10.  FR4 can be safely substituted when G10 is called out, while G10 can never be substituted where FR4 is called for.

Color: yellowish to light green

G10 specifies to MIL-I-24768/2 (GEE), MIL-P-18177 GEE and LP-509)

FR4 specifies to MIL-I-24768/27 (GEE-F) and MIL-P-18177 GEE-F

Mechanical ASTM Test Method Value Units
Strength to Weight Ratio - - ksi
Specific Gravity @73 F D792 1.82 -
Tensile Strength @73 F, (ult)/(yld) D638 40,000 psi
Tensile Modulus of Elasticity @73 F D638 - psi
Tensile Elongation at Break @73 F D638 - %
Flexural Strength @73 F D790 55,000 psi
Flexural Modulus of Elasticity @73 F D790 2,700,000 psi
Shear Strength @73 F D732 19,000 psi
Comprehensive Strength, (% Deformation) @73 F D695 60,000 (10) psi
Comprehensive Modulus of Elasticity @73 F D695 - psi
Hardness, Rockwell, Scale as noted @73 F D785 M110 -
Hardness, Durometer, Shore D @73 F D2240 - -
Izod Impact, (Notched) @73 F D256 Type A 7.0 ft-lb/in of notch
Coefficient of Friction, (Dry vs Steel) Dynamic - - -
Limiting PV, (with 4 to 1 factor of safety applied) - - psi-ft/min
Thermal ASTM Test Method Value Units
Coefficient of Linear Thermal Expansion @73 F E-831 (TMA) - in/in/F
Heat Deflection Temperature @264 psi D648 - F
Tg-Glass transition termperature, (Amorphous) D3418 - F
Melting Point, (VS=Vicat Softening Temp.) D3418 - F
Continuous Service Temperature in Air, (Max.) - 285 F
Thermal Conductivity - - BTU-in/hr-ft2-F
Electric ASTM Test Method Value Units
Dielectric Strength, Short Term D149 400 Volts/mil
Volume Resistivity D257 - ohm-cm
Dielectric Constant @10E6 Hz D150 5.2 -
Dissipation Factor @10E6 Hz D150 0.025 -
Flammability @3.1 mm unless noted UL94 V-0 -
H2O ASTM Test Method Value Units
Water Absorption, Immersion, 24 hours D570(7) 0.10 % by weight
Water Absorption, Saturation D570(7) - % by weight