FR-4 Halogen-Free
Flame-retardant grade
ASTM D709
Use when RoHS-plus / halogen-free (Br, Cl < 900 ppm) declarations are required by the customer or end market.
Values for the Halogen-Free condition
Other FR-4 grades and fills
FR-4 is listed in 19 conditions; see the grade overview at FR-4.
- NEMA-C
- NEMA-CE
- GPO-3
- GPO-1
- NEMA-L
- NEMA-LE
- NEMA-XXX
- NEMA-XX
- NEMA-X
- NEMA-G7
- NEMA-G3
- NEMA-G5
- NEMA-G9
- High-CTI
- Epoxy Matrix
- Halogen-Free
- High-Tg
- NEMA-FR5
- NEMA-G11
Compare all 19 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
NEMA Grade C | Coarse-weave cotton fabric / phenolic laminate — mechanical grade with high impact strength and good machinability; poor electricals. | — | 70 | — | 105 HRM |
NEMA Grade CE | Coarse cotton fabric / phenolic laminate with improved moisture and electrical performance over Grade C. | — | 70 | — | 105 HRM |
NEMA GPO-3 | Flame-retardant glass-mat polyester sheet with high arc and tracking resistance (CTI ≥ 600 V); standard switchgear insulation board. | — | 75 | — | 100 HRM |
NEMA GPO-1 | Glass-mat reinforced polyester sheet, general-purpose mechanical/electrical grade, non flame-retardant (UL 94 HB). | — | 80 | — | 100 HRM |
NEMA Grade L | Fine-weave linen/cotton fabric phenolic laminate — smoother finish and finer machined detail than Grade C, mechanical grade. | — | 85 | — | 108 HRM |
NEMA Grade LE | Fine-weave fabric phenolic laminate of electrical quality — best machining/finish of the cotton grades with usable dielectric strength. | — | 85 | — | 110 HRM |
NEMA Grade XXX (PBE) | Paper/phenolic electrical-grade laminate with minimum cold flow and low loss under humidity — classic radio/terminal-board material. | — | 100 | — | 105 HRM |
NEMA Grade XX | Paper/phenolic laminate of mechanical-and-electrical quality — better moisture resistance and dielectric behaviour than Grade X. | — | 110 | — | 105 HRM |
NEMA Grade X | Paper-reinforced phenolic laminate, mechanical grade — highest strength of the paper grades, electrical properties not guaranteed. | — | 125 | — | 105 HRM |
NEMA G-7 (GSG) | Silicone-resin / woven glass laminate — Class H thermal endurance (~220 °C), excellent arc resistance and low dielectric loss, modest strength. | — | 145 | — | 100 HRM |
NEMA G-3 (GPG) | Phenolic-resin / woven glass laminate — tough and impact resistant with fair electricals; largely superseded by G-10/FR-4. | — | 170 | — | 100 HRM |
NEMA G-5 (GMG) | Melamine-resin / woven glass laminate — very hard, high arc- and track-resistance, self-extinguishing; used for arc barriers and switchgear. | — | 205 | — | 120 HRM |
NEMA G-9 (GME) | Electrical-grade melamine / woven glass laminate — G-5 mechanicals with better dielectric performance under humidity and high arc resistance. | — | 215 | — | 120 HRM |
tracking-resistant grade (CTI ≥ 600 V) | Specify for high-voltage / EV / solar boards where creepage distances are set by IEC 60664 material group I. | — | 300 | 1.7 | 110 HRM |
Epoxy MatrixDefault standard difunctional FR-4 (Tg 130–140 °C) | Default choice for general PCB substrates, insulating plates, spacers and fixtures below ~130 °C. | — | 310 | 1.8 | 110 HRM |
Halogen-FreeThis page phosphorus/nitrogen flame retarded | Use when RoHS-plus / halogen-free (Br, Cl < 900 ppm) declarations are required by the customer or end market. | — | 310 | 1.7 | 110 HRM |
High-Tg FR-4 | Pick for lead-free reflow, multilayer/HDI boards or parts running above 130 °C where Z-axis expansion and via reliability matter. | — | 320 | 1.7 | 112 HRM |
NEMA FR-5 (GEB-F) | Heat-resistant multifunctional epoxy / woven E-glass laminate, flame-retardant (UL 94 V-0), retains strength to ~155 °C. | — | 320 | — | 112 HRM |
NEMA G-11 (GEB) | High-temperature epoxy / woven E-glass laminate (non flame-retardant, UL 94 HB) retaining ≥50 % of flexural strength at 150 °C. | — | 340 | — | 112 HRM |
What is FR-4 Halogen-Free?
FR-4 Halogen-Free is FR-4 in the Halogen-Free grade — use when RoHS-plus / halogen-free (Br, Cl < 900 ppm) declarations are required by the customer or end market. FR-4 Halogen-Free has a tensile strength of 310 MPa (45 ksi), stronger than 56% of composite grades. Elongation at break is 1.7% and the elastic modulus is 23 GPa (3.34 Msi). FR-4 Halogen-Free has a density of 1.85 g/cm³ (0.0668 lb/in³), heavier than 67% of composite grades. Its glass-transition temperature is 155°C (311 °F). Epoxy Matrix is the default condition FabDigit quotes; Halogen-Free is available on request or by drawing note.
Advantages
- Low moisture uptake — 0.12%, better than 78% of composite grades
FR-4 Halogen-Free properties
Typical room-temperature values for FR-4 Halogen-Free; 23 are specific to this condition. Other listed values are FR-4 reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
FR-4 Halogen-Free has a density of 1.85 g/cm³ (0.0668 lb/in³), heavier than 67% of composite grades. Its glass-transition temperature is 155°C (311 °F).
Mechanical12
FR-4 Halogen-Free has a tensile strength of 310 MPa (45 ksi), stronger than 56% of composite grades. Elongation at break is 1.7% and the elastic modulus is 23 GPa (3.34 Msi).
Thermal8
FR-4 Halogen-Free is rated for continuous service to 140°C (284 °F). It conducts heat at 0.4 W/m·K (0.231 BTU/hr·ft·°F), better than 53% of composite grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical7
FR-4 Halogen-Free is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of composite grades. UV resistance is fair.
Sustainability4
Producing a kilogram of FR-4 Halogen-Free takes about 95 MJ of energy and emits 6 kg of CO₂ — less than 72% of composite grades. Typical recycled content is 0%.
Manufacturability2
FR-4 Halogen-Free's machinability is fair (40/100, better than 57% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with FR-4 Halogen-Free
Is FR-4 easy to machine?
Machine dry with carbide or diamond-coated tools at high speed/low feed; glass is highly abrasive, so expect rapid tool wear, and capture the dust (respirable glass/epoxy) with local extraction.
Can FR-4 be welded?
Not weldable — a thermoset; join by adhesive bonding (epoxy), riveting or threaded inserts.
Can FR-4 be formed, bent or molded?
Supplied only as pressed flat sheet/rod/tube; no post-forming — parts are machined, routed, drilled or laser/water-jet cut, and layer count is set during lamination.
What surface finishes work on FR-4?
Deburr edges to avoid delamination and glass splinters; can be silkscreened, epoxy-painted, copper-etched and plated (through-hole Cu/Ni/Au), but never anodized or polished to a mirror finish.
FR-4 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| E-glass woven fabric (7628/2116/1080 styreinforcement, wt % | 50 – 65 | 58 |
| brominated flame retardant (TBBPA-derivewt % of the resin phase; absent in halogen-free grades | 12 – 20 | 17 |
| inorganic filler (silica / ATH)grade dependent | 0 – 10 | 3 |
| epoxy resin (DGEBA / multifunctional, cumatrix incl. hardener (dicy or phenolic) | ≥ 30 (balance) | — |
FR-4 Halogen-Free — frequently asked
What is FR-4 Halogen-Free used for?
FR-4 Halogen-Free is typically used for printed circuit board substrate, electrical insulators, standoffs and barriers, terminal boards and switchgear panels, transformer and busbar spacers, motor and battery pack insulation plates and test fixture and bed-of-nails plates. In short: bullet-proof glass alternative.
What is the tensile strength of FR-4 Halogen-Free?
FR-4 Halogen-Free has a typical tensile strength of 310 MPa (45 ksi) — stronger than 56% of composite grades. Strength varies by condition: see the 19 listed tempers.
Is FR-4 Halogen-Free easy to machine?
Not especially — machinability is rated fair (40/100, better than 57% of composite grades). Machine dry with carbide or diamond-coated tools at high speed/low feed; glass is highly abrasive, so expect rapid tool wear, and capture the dust (respirable glass/epoxy) with local extraction.
Can FR-4 Halogen-Free be welded?
Not weldable — a thermoset; join by adhesive bonding (epoxy), riveting or threaded inserts.
What surface finishes work on FR-4 Halogen-Free?
Deburr edges to avoid delamination and glass splinters; can be silkscreened, epoxy-painted, copper-etched and plated (through-hole Cu/Ni/Au), but never anodized or polished to a mirror finish.
Can FR-4 Halogen-Free be formed, bent or molded?
Supplied only as pressed flat sheet/rod/tube; no post-forming — parts are machined, routed, drilled or laser/water-jet cut, and layer count is set during lamination.
What is the maximum service temperature of FR-4 Halogen-Free?
FR-4 Halogen-Free is rated for continuous use to about 140°C (284 °F), and briefly to 180°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in FR-4 Halogen-Free?
Yes — FR-4 Halogen-Free is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- IPC-4101 Specification for Base Materials for Rigid and Multilayer Printed Boards — IPC (2021)
- NEMA LI-1 Industrial Laminating Thermosetting Products — NEMA (1998)
- Isola / Shengyi / ITEQ FR-4 laminate datasheets (S1141, S1000-2, IT-180A) — Isola, , ITEQ (2023)
- Garolite FR-4 / G-10 sheet property tables — McMaster-Carr / Röchling (2024)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.