NEMA G7 silicone glass cloth laminate sheets are high-temperature thermoset composite laminates composed of continuous woven glass cloth bonded with silicone resin binder. Engineered for extreme thermal and high-frequency electrical environments, NEMA G7 offers Class H (180 °C) continuous thermal resistance, high arc endurance, and ultra-low dielectric dissipation factors.
1. NEMA G7 Technical Property Matrix
Standardized properties for NEMA G7 / IEC 60893 SI GC 202 silicone glass laminate sheets across thermal, mechanical, and dielectric parameters:
| Specification Parameter | Standard Test Method | NEMA G7 / SI GC 202 Value |
|---|---|---|
| Continuous Operating Temperature | IEC 60216 Thermal Class | Class H (180 °C Continuous Duty) |
| Arc Resistance | ASTM D495 | ≥ 180 Seconds |
| Flammability Rating | UL 94 | UL 94 V-0 Rated |
| Flexural Strength (Flatwise, Room Temp) | ASTM D790 / ISO 178 | ≥ 150 MPa |
| Dielectric Strength (Perpendicular in Oil) | ASTM D149 / IEC 60243 | ≥ 12.0 kV/mm |
| Dissipation Factor (1 MHz) | ASTM D150 | ≤ 0.003 (Low Loss Factor) |
2. Key Performance Advantages & Engineering Limits
- Class H Thermal Endurance (180 °C): Retains structural integrity and dielectric strength under sustained temperatures up to 180 °C. Exceeding 200 °C for extended periods leads to gradual silicone binder embrittlement.
- Superior Arc & Tracking Resistance: Silicone resin chemistry resists carbon tracking under high-voltage arcing, making G7 ideal for switchgear arc chutes and high-energy plasma barriers.
- Low Moisture Absorption & Dielectric Loss: Exhibits water absorption below 0.35% (24-hour immersion), maintaining low dielectric constant and dissipation factors in high-humidity ambient conditions.
- Mechanical Strength Consideration: Room-temperature flexural and tensile strength of G7 is lower than FR4 / G10 Epoxy Laminates. Where high mechanical impact is required at lower temperatures, FR4 or G11 should be specified.
3. Primary Industrial Applications
- High-Temperature Transformers: Dry-type transformer core insulation, spacer blocks, and high-voltage terminal barriers operating at Class H temperatures.
- Switchgear & Circuit Breakers: Arc chutes, arc-extinguishing plates, phase barriers, and high-voltage switch contacts exposed to repetitive electrical arcing.
- High-Frequency & RF Heating Equipment: Non-conductive structural supports in high-frequency induction furnaces, RF heating fixtures, and radar equipment requiring minimal dielectric loss.
4. Frequently Asked Questions (FAQ)
Q: How does NEMA G7 compare to NEMA G11 laminate sheets?
A: NEMA G7 utilizes silicone resin rated for Class H (180 °C continuous) with exceptional arc resistance (≥ 180s) and low dielectric loss. NEMA G11 utilizes modified epoxy resin rated for Class F (155 °C continuous) with significantly higher room and elevated flexural strength. Choose G7 for higher heat and arc resistance; choose G11 for structural strength at 155 °C.
Need NEMA G7 Silicone Glass Sheets or Custom CNC Machined Parts?
Contact RDS Composite technical sales team for certified TDS datasheets, sample orders, and direct B2B volume pricing.
Request a Quote for NEMA G7