G10 glass fiber board, fully named G10 epoxy glass cloth laminate, is a composite material reinforced with alkali-free glass fiber cloth and phenolic-modified epoxy resin as the matrix, formed under high temperature and pressure. Compared to the most common FR4 (which uses dicyandiamide-cured epoxy resin), G10 offers significantly superior mechanical strength, moisture-heat resistance, and dimensional stability—particularly in harsh operating environments with high temperature, high humidity, and high altitude. As a result, G10 is widely preferred in transformer, rail transit, and industrial motor insulation applications.
I. Core Differences Between G10 and FR4
Many procurement engineers and buyers often confuse G10 with FR4, but the two materials differ fundamentally in resin system and application scenarios:
| Dimension | G10 Glass Fiber Board | FR4 Glass Fiber Board |
|---|---|---|
| Resin System | Phenolic-modified epoxy resin | Dicyandiamide-cured epoxy resin |
| Glass Transition Temperature (Tg) | 140?80°C (high-temp grades up to 200°C+) | 130?70°C |
| Flexural Strength | >400 MPa | 300?50 MPa |
| Water Absorption | Extremely low (<0.05%, 24h immersion) | 0.1%?.2% (24h immersion) |
| Moisture & Heat Resistance | Excellent ?stable in hot-humid conditions | Moderate ?prone to delamination in high humidity |
| Primary Applications | Transformer insulation, rail transit, high-voltage motors | PCB substrate, general power adapters |
| Cost | Higher | Cost-effective |
II. Core Performance Parameters of G10 Glass Fiber Board
2.1 Electrical Insulation Performance
G10's dielectric constant (εr) at 1 MHz is approximately 4.0?.5, with a dissipation factor (tan δ) of about 0.015?.020—roughly equivalent to FR4. However, thanks to its denser resin structure, G10 offers superior arc resistance and tracking resistance. Dielectric strength typically exceeds 22 kV/mm, and volume resistivity exceeds 10¹?Ω·cm, reliably blocking leakage paths in high-voltage environments.
2.2 Mechanical Strength and Dimensional Stability
G10 flexural strength typically exceeds 400 MPa (with some high-performance grades reaching 500 MPa+), far surpassing FR4's 300?50 MPa. Additionally, G10 has a lower coefficient of thermal expansion and extremely low water absorption (<0.05%), meaning that after long-term high-temperature and high-humidity operation, G10's dimensional stability and interlaminar bonding strength do not significantly degrade. This makes G10 especially suitable for insulation support structures subject to sustained mechanical stress.
2.3 Thermal and Flame-Retardant Performance
G10's rated operating temperature is typically 130?55°C, with short-term heat resistance reaching above 180°C. Its UL94 flammability rating is V-0, meeting strict industrial flame-retardancy requirements. High-Tg G10 (phenolic epoxy optimized formulations) can elevate Tg to above 180°C, further extending its suitability for high-temperature applications such as rail transit traction motors and high-power PV inverters.
III. Typical Industrial Application Scenarios
3.1 Transformer Insulation
In power transformers and reactors, G10 is commonly used for phase-to-phase insulation barriers, core end plates, and high-voltage lead supports. These components must endure operating temperatures above 120°C over long periods while maintaining stable insulation performance during humid seasons. G10's low water absorption and excellent high-temperature mechanical retention make it a preferred insulation material among transformer manufacturers.
3.2 Rail Transit and New Energy Vehicles
Onboard electrical equipment in rail transit vehicles—traction motors, inverters, and battery chargers—have stringent requirements for vibration resistance and wide-temperature cycling. Similarly, onboard chargers (OBC) and DC-DC converters in new energy vehicles require high-temperature-resistant, high-strength insulation support components. G10's vibration damping characteristics and broad temperature range stability make it widely adopted in both rail transit and new energy sectors.
3.3 Industrial Motors and High-Voltage Equipment
In large industrial motors, variable frequency drives (VFDs), and high-voltage switchgear, G10 is frequently used for slot liners and end-winding insulation. Compared to organic insulation materials like NOMEX paper, G10 offers higher mechanical strength and better resistance to oil and chemical media, enabling it to work with insulation varnish to form a complete insulation system.
IV. Selection and Procurement Recommendations
When procuring G10 glass fiber boards, key parameters to confirm include:
- Board Thickness and Dimensions: Standard thickness range 1.0?.0mm; standard sheet size 1020×1220mm. Custom cutting to any required dimension available.
- Tg Temperature Grade: Select Tg135, Tg150, or high-temperature grade Tg180+ based on actual operating temperature.
- Flammability Rating: UL94 V-0 is the baseline for industrial applications; some rail transit customers additionally require EN45545 compliance.
- Certification Documents: Request RoHS/REACH compliance declarations, UL Yellow Card certification, and factory test reports.
- Incoming Inspection: Recommend simple spot checks on thickness tolerance, flatness (warpage), and electrical strength for each batch.
| Parameter | Standard Grade | High-Performance Grade |
|---|---|---|
| Board Thickness | 1.0?.0mm | 0.5?2mm (custom available) |
| Board Size | 1020×1220mm | Any dimension, cut to drawing |
| Tg Temperature | 135°C / 150°C | Above 180°C |
| Flammability Rating | UL94 V-0 | UL94 V-0 + EN45545 |
| Water Absorption | ?.1% | ?.05% |
| Flexural Strength | ?00 MPa | ?00 MPa |
About Us: Dongguan Chaorong Electronics Co., Ltd. specializes in supplying G10 glass fiber board, FR4 glass fiber board, carbon fiber board, Bakelite board, and precision-machined PC/acrylic parts. Standard grades are in stock; small MOQs and custom cutting to drawing are supported, with RoHS/UL certifications provided.