What Are FR4, G10, and G11 Epoxy Sheets?

FR4, G10, and G11 epoxy sheets are high-performance electrical insulation materials manufactured by impregnating woven E-glass fabric with epoxy resin, followed by high-temperature and high-pressure lamination.

These laminate sheets offer excellent electrical insulation, high mechanical strength, outstanding chemical resistance, dimensional stability, and excellent machinability. They are widely used in transformers, electric motors, high- and low-voltage switchgear, new energy systems, power electronics, railway transportation, wind power, and industrial automation.

Although all three materials belong to the fiberglass-reinforced epoxy laminate family, they differ significantly in flame retardancy, thermal resistance, and recommended operating environments. Selecting the appropriate material can improve equipment reliability while reducing overall manufacturing costs.

FR4 vs G10 vs G11 Performance Comparison

Main Applications of FR4, G10, and G11 Epoxy Sheets

FR4 Epoxy Sheet

FR4 is the most widely used flame-retardant fiberglass epoxy laminate.

Typical applications include:

• Transformers and electric motors
• PCB insulation and electronic equipment
• EV battery packs
• Power distribution cabinets
• Power electronic equipment
• CNC-machined insulation components

G10 Epoxy Sheet

G10 provides outstanding mechanical strength and electrical insulation and is ideal for applications where flame retardancy is not required.

Typical applications include:

• Power transformers
• Motor slot insulation
• Mechanical support components
• Industrial fixtures
• Semiconductor equipment
• Insulation parts for automation equipment

G11 Epoxy Sheet

G11 is a high-temperature electrical insulation material specifically designed for long-term operation under elevated temperatures.

Typical applications include:

• High-voltage motors
• Generators
• Dry-type transformers
• Wind power equipment
• Railway transportation
• Aerospace electrical equipment
• High-temperature insulation structural components

FR4, G10, and G11 Epoxy Sheet Manufacturing Process

Manufacturing Process at Xujue Electrical, a ZTelec Group Factory

1. Resin Mixing

Epoxy resin, hardener, solvents, and other additives are mixed according to specified formulations.

• Mixing time: 2–8 hours
• Temperature: 5–43°C

2. Resin Impregnation

The fiberglass cloth is uniformly impregnated with resin to ensure complete wetting without dry spots or resin agglomeration.

3. Drying (B-Staging)

The impregnated fiberglass cloth is dried under controlled conditions.

• Temperature: 100–180°C
• Production line speed: 3–13 m/min

4. Lay-Up

The prepreg sheets are stacked according to product thickness requirements.

• Surface fabric layers: ≥2 sheets
• Reference weight: approximately 4.3 kg per 1 mm thickness
• Polyester release films are placed on both the upper and lower surfaces.

5. Hot Press Lamination

The stacked materials are laminated under high temperature and pressure.

• Temperature: 70–160°C
• Pressure: 3–17 MPa
• Cooling temperature: ≤60°C

6. Cutting

The laminated sheets are cut using appropriate cutting equipment based on product specifications, ensuring smooth and clean edges.

7. Inspection

Each sheet undergoes strict quality inspection to verify:

• Flat surface
• No burrs
• No delamination
• Accurate dimensions
• Compliance with quality standards

8. Warehousing

Finished products are stored in a clean, dry environment.

Storage management includes:

• Classified storage
• Organized stacking
• Inventory registration
• FIFO (First-In, First-Out) inventory control

How to Choose the Right Epoxy Sheet

If your equipment must comply with flame-retardant requirements—such as switchgear, power distribution equipment, or EV battery systems—FR4 epoxy sheet is the recommended choice.

If cost-effectiveness is the primary consideration and flame retardancy is not required, G10 epoxy sheet offers excellent electrical insulation and mechanical strength, making it one of the best-value materials for transformers, motors, and industrial equipment.

If your equipment operates continuously under high temperatures, high voltage, or harsh environments—such as large electric motors, generators, dry-type transformers, or wind turbines—G11 epoxy sheet is the preferred solution. Its higher thermal class enables it to maintain excellent mechanical properties and electrical insulation even at elevated temperatures.

Choose a Professional FR4, G10, and G11 Epoxy Sheet Manufacturer

ZTelec Group specializes in the research, development, and manufacturing of high-performance electrical insulation materials. We supply premium-quality FR4, G10, and G11 epoxy sheets, as well as precision-machined insulation components.

We offer:

• FR4 Epoxy Sheets
• G10 Epoxy Sheets
• G11 Epoxy Sheets
• CNC Precision-Machined Insulation Parts
• Custom thicknesses from 0.2 mm to 100 mm
• Customized dimensions, colors, and specifications
• OEM & ODM manufacturing services
• Fast sample support
• Professional technical consultation
• Worldwide export services

Our products are widely used in transformers, electric motors, high- and low-voltage switchgear, railway transportation, renewable energy, wind power, and industrial automation.

If you are looking for a reliable supplier of FR4, G10, or G11 epoxy sheets, contact our technical team today. We will recommend the most suitable material based on your application requirements and provide professional technical support and customized insulation solutions.