The Basics: What are G10 and FR4?
G10 and FR4 are both comprised of a continuous glass woven fabric impregnated with an epoxy resin binder. For many years, they were considered interchangeable, but there is one defining difference:
- G10 Epoxy Fiber Glass: The standard industrial grade. It offers high mechanical strength and excellent electrical insulation in dry and humid conditions.
- FR4 Epoxy Fiber Glass: Essentially G10 with the addition of bromine, a flame-retardant additive. Today, FR4 has largely replaced G10 in most PCB applications because it meets the strict UL94 V-0 flammability standards.
We also provide specialized versions like FR4/G10 FRP Rods and ESD/Antistatic G10 or ESD FR4 Sheets for environments sensitive to static discharge.
G11: The High-Temperature Powerhouse
If FR4 and G10 are the “workhorses,” then G11 Epoxy Glass Fiber is the high-performance athlete. G11 is designed for applications where heat is a constant factor.
The primary advantage of G11 over FR4/G10 is its Heat Resistance (Tg). While FR4 typically maintains its properties up to 130°C, G11 retains high mechanical strength even at temperatures exceeding 155°C to 180°C.
Key Performance Comparison
| Feature | G10 / FR4 | G11 |
|---|---|---|
| Max Operating Temp | ~130°C | 155°C – 180°C |
| Flame Retardancy | Yes (FR4 only) | Variable (Specify FR5) |
| Mechanical Strength | Excellent | Superior at High Temps |
| Dielectric Strength | High | Very High |
When to Choose G11 over FR4?
You should specify G11 if your project involves:
- Extreme Thermal Cycling: Environments where the material must not become brittle or lose its shape under heat.
- High-Voltage Insulation: G11 is often used in power generation, switchgear, and transformers.
- Structural Rigidity: When the material acts as a primary support in aerospace or cryogenic applications.
For applications that require both the high-temp performance of G11 and flame retardancy, FR5 Epoxy Fiber Glass is the upgraded flame-retardant version of G11.
Other Specialized Insulators
Depending on your specific industry needs, Cylex Plastics offers alternatives for different budgets and environments:
- GPO-3 (UPGM203): Excellent for arc and track resistance in electrical applications.
- Wave Solder Pallet (Durostone): Specifically engineered for the PCB soldering process.
- Phenolic Canvas (Grade CE): Ideal for mechanical gears and wear components where electrical properties are secondary.
- ESD Bakelite: A cost-effective solution for static-safe jigs and fixtures.
Conclusion
While FR4/G10 remains the standard for most PCB supports and general electrical insulation, G11 is indispensable for high-heat industrial environments. Choosing the right grade ensures the longevity of your components and the safety of your systems.
Not sure which grade fits your specs? View our full Composites range or contact the Cylex Plastics team for expert technical support and custom fabrication services.
