G10 Specifications — Sizes, Tolerances & NEMA LI 1 Standards
G10 specifications are governed primarily by NEMA LI 1, the standard for industrial laminated thermosetting products. NEMA LI 1 sets minimum property requirements for G10 sheet, rod, and tube, including dimensional tolerances, surface quality, flexural strength minimums, electrical property minimums, and thermal classification. The military equivalent is MIL-I-24768/2 (Type GEE), which mirrors NEMA LI 1 requirements and adds procurement and traceability requirements. ASTM D709 is referenced for test methods but does not set minimum values independently.
At a glance:
- Governing standard: NEMA LI 1 (sheet/rod/tube), MIL-I-24768/2 Type GEE (military)
- International equivalent: IEC 60893, EPGC 201/202
- Standard sheet panels: 24" × 36", 36" × 48", 48" × 96"
- Sheet thickness range: 0.005" to 4.0" standard; heavier plate to order
- Rod diameter range: 0.125" to 4.0"; standard lengths 4 ft and 8 ft
- Color: natural (green-tinted or beige/olive); black available
- Surface finish: smooth or mat (linen-textured surface available)
Governing Standards
NEMA LI 1
NEMA LI 1 is published by the National Electrical Manufacturers Association and covers all industrial-grade laminated thermosetting products. For G10 specifically, NEMA LI 1 defines:
- Minimum flexural strength (lengthwise and crosswise)
- Minimum dielectric strength (short time and step-by-step)
- Maximum water absorption (24-hour and boiling water)
- Dimensional tolerances for sheet, rod, and tube
- Color designation (natural = N; black = B)
- Thermal classification (Grade G10 = Class B, 130°C)
MIL-I-24768/2 (Type GEE)
The military specification MIL-I-24768/2 is the defense procurement equivalent of NEMA LI 1 for glass-epoxy laminates. Type GEE designates G10. Type GEE/FR designates FR4. When procurement documents reference MIL-I-24768 Type GEE, G10 per NEMA LI 1 with appropriate certification is typically acceptable; always verify with the contracting activity.
ASTM D709 and IEC 60893
ASTM D709 is the standard specification for laminated thermosetting materials, broadly covering phenolics, melamines, silicones, and epoxies. ASTM D709 references ASTM test methods for each measured property but defers to NEMA LI 1 for minimum values in commercial practice.
IEC 60893 is the international equivalent and defines G10 approximately as EPGC 201 (standard epoxy glass cloth, general purpose) or EPGC 202 (flame-resistant variant = FR4 equivalent).
Sheet Specifications
Standard Sheet Panel Sizes
| Panel Size | Availability |
|---|---|
| 24" × 36" | Standard stock |
| 36" × 48" | Standard stock |
| 48" × 96" | Standard stock |
| Custom cut-to-size | Available from all panel sizes |
Thickness Range and Tolerances
These are standard mill tolerances per NEMA LI 1. Tighter thickness tolerances are achievable by surface grinding or precision lapping. Specify tolerance requirement clearly when ordering — mill-to-tolerance and grind-to-tolerance material carry different lead times and pricing.
Surface Finish
G10 sheet has two standard surface conditions:
- Smooth (polished): Standard production finish — surfaces are flat and smooth as produced by the press platens
- Mat (textured): Linen-textured surface pattern from the press release film; useful for bonding applications where mechanical keying improves adhesion
Both surfaces can be lightly sanded or media-blasted for further surface prep. Edges as-cut are typically square-sawn; machine-finished edges are available on custom parts.
Rod Specifications
Standard Diameters and Lengths
| Diameter Range | Standard Lengths |
|---|---|
| 0.125" – 0.500" | 4 ft, 8 ft |
| 0.500" – 2.000" | 4 ft, 8 ft |
| 2.000" – 4.000" | 4 ft |
| > 4.000" | Consult for availability |
Rod Tolerances
Tube Specifications
G10 tube is produced by filament winding or by rolling and bonding sheet into tubular form. Filament-wound tube has superior hoop strength and consistent wall thickness.
Standard Tube Parameters
| ID Range | Wall Thickness Range |
|---|---|
| 0.250" to 1.000" | 0.060" to 0.250" |
| 1.000" to 3.000" | 0.125" to 0.500" |
| 3.000" to 6.000" | 0.250" to 0.750" |
Color and Identification
G10 laminate is produced in two standard colors:
- Natural: Green-tinted translucent to olive/beige depending on the glass cloth and resin batch. Color varies between manufacturers and lots.
- Black: Carbon black or pigment added to resin system. Electrically equivalent to natural; color does not affect electrical or mechanical properties.
Color is not a reliable indicator of material grade. Both G10 and FR4 are commonly produced in natural green and black. When grade certification matters, request a NEMA LI 1 or MIL-I-24768/2 certificate of conformance — not color alone.
Certification and Documentation
For NEMA LI 1 standard material, typical documentation includes:
- Material test report with lot number and test date
- Certification of conformance to NEMA LI 1 Grade G10
For MIL-I-24768/2 (Type GEE) material:
- Certified test report per MIL requirements
- Manufacturer's certification to the specification
- Lot traceability documentation
For custom-tolerance or ground sheet:
- Inspection certificate with measured thickness values
- Flatness measurement report (on request)
Order G10 to NEMA LI 1 or MIL-I-24768/2 — cut to size available
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