Electrical insulation, heat resistance and mechanical strength for power equipment, switchboards and electronics fixtures.
These sheets are made by laminating glass fiber cloth with epoxy resin under high temperature and pressure, in FR4 / G10 grades. They offer good electrical insulation (volume resistivity ≥10¹² Ω·cm), heat resistance (continuous use 110–150 °C depending on grade), high mechanical strength and low water absorption, and are common for insulating barriers in power equipment, electronics process fixtures and switchboard base plates. We offer many thicknesses and custom cutting.
What is FR4 / G10?
Epoxy glass fiber sheet (also called FR4 sheet or G10 sheet) is a thermoset composite made by impregnating continuous glass fiber cloth with epoxy resin, then laminating and curing it under heat and pressure. NEMA LI 1 classifies these laminates by flame retardance and temperature performance: FR4 is the common flame-retardant grade (FR = flame retardant), FR5 is flame retardant with a higher temperature rating, and G10 is the basic grade without flame retardant. FR4 and G10 look alike and are both green, but FR4 is self-extinguishing.
NEMA grade comparison
| Grade | Color | Continuous temperature | Flame retardance | Key properties | Common uses |
|---|---|---|---|---|---|
| G10 | Green | 110–120 °C | — | Good insulation, high mechanical strength, low water absorption | Fixture base plates, insulating barriers, structural supports |
| FR4 | Green / yellow / black | 140–150 °C | Self-extinguishing (FR4 grade) | Self-extinguishing, good insulation, high strength | PCB substrates, switchboard insulation, equipment barriers |
| FR5 | Yellow | 160–170 °C | Self-extinguishing (FR5 grade) | High temperature, high strength | High-temperature insulation, reflow fixtures |
| FR4 (ESD) | Black | 120–130 °C | — | Antistatic (surface resistance 10⁶–10⁸ Ω) | Semiconductor fixtures, ESD-sensitive areas |
Technical data (typical)
| Parameter | Typical value |
|---|---|
| Material | Epoxy resin + glass fiber cloth, laminated under heat and pressure |
| Color | Green (G10 / FR4 standard) |
| Thickness | 0.2–100 mm (custom) |
| Volume resistivity | ≥ 10¹² Ω·cm |
| Surface resistance | ≥ 10¹¹ Ω |
| Dielectric strength | ≥ 14.2 kV/mm (perpendicular to laminations) |
| Flexural strength | ≥ 340 MPa |
| Water absorption | ≤ 0.1% (24 h immersion) |
| Continuous use temperature | 110–150 °C (by grade) |
| Flame retardance | Self-extinguishing (FR4 grade) |
Tip: for semiconductor or electronics assembly areas, check whether you need the antistatic version (FR4-ESD, black). For general insulation, standard green G10 or FR4 is enough. For sheets thicker than 50 mm, please confirm lead time in advance.
Applications
| Application | Description | Suggested grade |
|---|---|---|
| Switchboard / switch box barriers | Electrical isolation between busbars against short circuits and arcing | FR4 (self-extinguishing) |
| Electronics fixture base plates | Base plates for SMT, assembly or test fixtures; dimensionally stable and insulating | G10 or FR4 |
| Motor / transformer insulating spacers | Insulation between coils or at winding ends; heat and stress resistant | FR4, or FR5 for high temperature |
| Semiconductor process fixtures | ESD-sensitive areas needing insulation and static dissipation | FR4 (ESD), black |
| Structural supports / spacers | Light, strong parts replacing metal and avoiding conduction | G10 |
Selection summary
| Factor | Consideration |
|---|---|
| Flame retardance | Inside electrical equipment and switchboards, choose FR4 or higher (self-extinguishing); G10 for non-electrical uses |
| Temperature | General use G10 (120 °C) or FR4 (150 °C); high-temperature processes FR5 (170 °C) |
| Antistatic | Semiconductor / electronics assembly ESD areas: black FR4 (ESD), 10⁶–10⁸ Ω |
| Thickness and size | 0.2–100 mm, custom cut to drawing |
| Machining | Can be drilled, milled and CNC machined; cutting creates glass fiber dust, so use protection |
Request a quote
Tell us the grade, thickness, size and quantity, and we will reply with price and lead time. For custom sizes or special thicknesses, send a drawing or dimensions and we can suggest a suitable grade and machining. Request a quote →