FR4 sheet is a glass fiber reinforced epoxy resin composite material. It uses epoxy resin as the adhesive and electronic grade continuous filament glass fiber cloth as the reinforcing material. It is dimensionally stable, smooth surface, impact-resistant, moisture-proof and high-temperature resistant. FR-4 is not a material name but a code for a flame-retardant material grade, indicating the standard that resin materials must be able to self-extinguish after burning. The name FR4 comes from the NEMA classification system, where ‘FR’ stands for ‘Flame Retardant’, and complies with the UL94V-0 standard.
Basic Specifications of FR4 Sheets
- Material: Fiberglass cloth + epoxy resin.
- Color: Natural, Green, yellow, black, white, etc.
- Thickness: 0.1~50mm.
- Size：1020*1220, 1020*2040, 1220*2040, 1220*2440mm, or customized.
- Working Temperature: ≤170℃.
- Type: G10/FR4.
Features of FR4 Sheets
Flat Surface
It is dimensionally stable and insensitive to changes in temperature and humidity.
Flame Retardant
The flame retardant grade reaches FV0 (stops burning within 10 seconds after the flame source is withdrawn, and no dripping occurs).
Impact Resistance
R4 sheet performs well in mechanical strength properties, with high bending strength and elastic modulus.
Performance Parameters of FR4 Sheets
| Vertical layer bending strength A | E-1/150, 150±5℃≥340Mpa |
| Parallel layer impact strength | ≥230KJ/m |
| Insulation resistance after water immersion (D-24/23) | ≥5.0×108Ω |
| Vertical layer electrical strength (in 90±2℃ transformer oil, plate thickness 1mm) | ≥14.2MV/m |
| Parallel layer breakdown voltage (in 90±2℃ transformer oil) | ≥40KV |
| Relative dielectric constant (50Hz) | ≤5.5 |
| Relative dielectric constant (1MHz) | ≤5.5 |
| Dielectric loss factor (50Hz) | ≤0.04 |
| Dielectric loss factor (1MHz) | ≤0.04 |
| Water absorption (D-24/23, plate thickness 1.6mm) | ≤19mg |
| Density | 1.70-1.90g/cm³ |
| Flammability | FV0 |
Applications of FR4 Sheets
PCB (electronic circuit board)
FR4 provides good electrical insulation properties, mechanical strength and heat resistance to ensure the stability and reliability of PCB.
Electrical insulation material
FR4 sheet has super insulation performance and high temperature stability, so it can ensure the safety of equipment when used in power systems.
Laminated Composite Panels
FR4 can be used as a skin material combined with core materials of other materials to make composite panels. Such as solar back panels, pickleball paddles, etc.
Daily necessities
FR4 sheets can be used as gaskets, LED light boards, storage boxes, etc. in kitchens, bathrooms, and bedrooms. They are strong, durable and reusable.
FR4 Sandwich Panels
Choosing lightweight, high-strength core materials can provide higher mechanical strength and stability for FR4 sandwich panels. Usually, these core materials include foam boards (XPS, PET, PVC, PMI, etc.), plywood, PP honeycomb, etc.
