FR4 vs G10 vs 3240 Epoxy Board: A Complete Industrial Insulation Material Guide
Introduction
Insulation material selection directly impacts the safety, reliability, and service life of electrical and industrial equipment. FR4, G10, and 3240 epoxy board are three of the most common fiberglass insulation materials. Though similar in appearance, they differ significantly in performance and cost. This article provides a detailed comparison to help you make the right selection.
1. Material Overview
1.1 FR4 Epoxy Board
FR4 (Flame Retardant 4) is the most widely used base material for printed circuit boards (PCBs), composed of epoxy resin reinforced with fiberglass cloth.
Key Characteristics: - Flame retardancy: UL94 V-0 - Fiberglass cloth grades: 7628, 2116, 1080, etc. - Color: Typically green, also available in yellow and black - Standard thickness: 0.8mm-3.0mm
Advantages: - Lower cost, mature supply chain - Excellent machinability, easy to cut and drill - Stable electrical performance
Disadvantages: - Moderate high-temperature performance (TG ~130-140℃) - Limited flexibility for large custom orders
1.2 G10 Epoxy Board
G10 (Grade 10) shares the same composition as FR4 (epoxy + fiberglass), but is specifically designed for industrial applications under NEMA standards.
Key Characteristics: - Standard: NEMA LI 1-1998 - Does not contain flame retardants (separate testing required) - Color: Typically light yellow/natural - Military-grade quality requirements
Advantages: - Higher mechanical strength than FR4 - Lower water absorption, better in humid environments - Superior dimensional stability
Disadvantages: - ~20-30% more expensive than FR4 - Flame retardancy requires separate verification
1.3 3240 Epoxy Board
3240 is a Chinese standard designation for epoxy board, following GB/T 1303 series national standards, belonging to the phenolic-modified epoxy system.
Key Characteristics: - Standard: GB/T 1303.1-2009 - Thickness range: 0.5mm-50mm - Color: Yellow/brown-yellow - Phenolic-modified epoxy system
Advantages: - Complete thickness range, ample stock available - Better high-temperature resistance than standard FR4 (~155℃) - High cost performance, preferred for domestic substitution
Disadvantages: - Significant quality variation between manufacturers - Slightly higher water absorption than G10
2. Detailed Performance Comparison
| Parameter | FR4 | G10 | 3240 Epoxy |
|---|---|---|---|
| Density (g/cm³) | 1.8-1.9 | 1.8-1.9 | 1.7-1.9 |
| Water Absorption (%) | ≤0.10 | ≤0.05 | ≤0.10 |
| Flexural Strength (MPa) | ≥340 | ≥400 | ≥350 |
| Tensile Strength (MPa) | ≥300 | ≥350 | ≥300 |
| Dielectric Strength (kV/mm) | ≥20 | ≥20 | ≥20 |
| Max Temp (℃) | 130-140 | 130-140 | 150-155 |
| Flame Rating | UL94 V-0 | None (additive) | UL94 V-0 |
| Primary Use | PCB, Electronics | Military, Industrial | Transformers, Motors |
3. Application Scenarios
3.1 Power Adapters
Recommended: FR4 or 3240
For 65W-300W power adapters, FR4 and 3240 are the most economical choices: - Transformer insulation spacers: 2.0mm-3.0mm thickness - PCB support pillars: 1.0mm-1.6mm thickness - Heatsink insulation pads: 0.8mm-1.0mm thickness
3.2 EV Charging Stations
Recommended: G10 or 3240
7kW-22kW charging stations demand higher insulation performance: - High-voltage insulation spacers: Choose 3.0mm+ - Electrical isolation boards: G10 preferred (low water absorption) - IGBT module insulation: G10 or high-TG FR4
3.3 Drone Industry
Recommended: FR4 or Carbon Fiber Composite
Drones are weight and strength sensitive: - Frame panels: FR4 fiberglass board (2.0mm-3.0mm) - Motor insulation pads: FR4 (0.8mm-1.0mm) - GPS mounts: Carbon fiber board (lighter weight)
3.4 Transformers and Motors
Recommended: 3240 or G10
Transformers and motors demand high temperature resistance and mechanical strength: - Transformer insulation tubes: 3240 sheet or tube - Motor slot insulation: G10 thin sheets (0.5mm-1.0mm) - End insulation spacers: 3240
4. Selection Decision Tree
` Start Selection │ ├─ UL94 V-0 flame retardancy required? │ │ │ ├─ Yes → Cannot choose G10 (unless flame retardant added) │ └─ No → G10 is an option │ ├─ Operating temperature exceeds 140℃? │ │ │ ├─ Yes → Choose 3240 (155℃) or high-TG FR4 │ └─ No → All three options work │ ├─ Humid/outdoor environment? │ │ │ ├─ Yes → Prefer G10 (lowest water absorption) │ └─ No → Prefer FR4 (lowest cost) │ └─ Need large thickness (>10mm)? │ ├─ Yes → Prefer 3240 (up to 50mm thick sheets) └─ No → All three options work `
5. Machining Guidelines
5.1 Cutting
- Laser Cutting: High precision, small heat-affected zone, ideal for complex shapes (recommended for FR4, G10) - CNC Precision Cutting: No heat affected zone, suitable for thick sheets (recommended for 3240) - Sawing: Low cost, suitable for high-volume straight cuts
5.2 Drilling
- FR4 and G10 drill cleanly with carbide drill bits - 3240 is more brittle — reduce RPM to prevent cracking - Micro-holes (<2mm) recommend laser processing
5.3 Surface Treatment
- Silk Screening: FR4 and 3240 surfaces accept direct silk screening - Anodizing: Not applicable for epoxy boards - Conformal Coating: Recommended for humid environments
6. Chaorong Electronics Summary
| Application | Recommended Material | Thickness |
|---|---|---|
| Consumer Electronics PCB | FR4 | 0.8-1.6mm |
| Power Adapters | FR4 or 3240 | 1.0-3.0mm |
| EV Charging Stations | G10 or 3240 | 2.0-5.0mm |
| Drone Frames | FR4 or Carbon Fiber | 2.0-3.0mm |
| Transformer Insulation | 3240 | 3.0-10mm |
| Military/Industrial Premium | G10 | Custom per drawing |
Conclusion
FR4, G10, and 3240 each have their advantages. There is no absolute "best" — only the most suitable choice. Consider flame retardancy requirements, operating temperature, humidity environment, mechanical strength, and cost budget when selecting.
Chaorong Electronics offers a full range of epoxy board materials with custom processing support and free technical consultation.
--- About Chaorong Electronics Dongguan Chaorong Electronic Products Co., Ltd. specializes in manufacturing FR4 fiberglass board, 3240 epoxy board, and G10 insulation board. Complete specifications available with CNC precision cutting, laser cutting, drilling, and routing services.
📞 Hotline: +86 134-3388-5009 🌐 Website: www.dggbsr.com