FR-2
ASTM D709 Grade FR-2, D709 Type FR-2
FR-2 is a flame-retardant phenolic-paper laminate to ASTM D709 (Grade FR-2 / Type FR-2), supplied unclad or copper-clad in single- and double-sided constructions with 18, 35 and 70 µm foil, plus cold-punch (CP) and hot-punch (HP) grades.
Reference datasheet — FR-2 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the CCL-1S-35 condition
FR-2 grades and fills
FR-2 is supplied in 6 conditions, soft to hard. CCL-1S-35 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Cold-punch grade | Standard FR-2 formulation optimized for room-temperature blanking of small boards at high volume (equivalent of XXXPC + FR). | 78 | 1.3 | 100 HRM | |
Single-sided copper-clad, 18 µm (1/2 oz) foil | Fine-line, low-current consumer boards where etch definition matters more than current capacity. | 88 | 1.1 | 105 HRM | |
CCL-1S-35Default Single-sided copper-clad, 35 µm (1 oz) foil | The default FR-2 CCL for mass-market single-sided PCBs: room-temperature punchable, cheapest board stock. | 92 | 1.1 | 105 HRM | |
Warm-punch / higher-strength grade | Slightly higher resin content and strength for thicker boards (≥2 mm) or crack-sensitive blanking; needs pre-heating before punching. | 95 | 0.9 | 110 HRM | |
Double-sided copper-clad, 35 µm both faces | Used only where jumper/rivet interconnect is acceptable — FR-2 paper core cannot reliably support plated through-holes. | 98 | 1.2 | 105 HRM | |
Single-sided copper-clad, 70 µm (2 oz) foil | Higher current-carrying tracks for power supplies, ballasts and adapters; slightly harder to punch cleanly. | 100 | 1.2 | 105 HRM |
Supply forms, finishes and certifications
Ways FR-2 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
UNCLAD | Bare flame-retardant paper-phenolic laminate sheet | Surface finish |
What is FR-2?
FR-2 is a flame-retardant phenolic-paper laminate to ASTM D709 (Grade FR-2 / Type FR-2), supplied unclad or copper-clad in single- and double-sided constructions with 18, 35 and 70 µm foil, plus cold-punch (CP) and hot-punch (HP) grades. Density is about 1.55 g/cm³ and service temperature is limited to 105 °C. It is the low-cost substrate for single-sided consumer electronics boards because it blanks and pierces cleanly in shear dies instead of requiring routing. The paper core absorbs moisture, holes cannot be plated, and mechanical and thermal performance is well below glass-epoxy — use FR-3 or FR-4 for double-sided and plated-through designs. FR-2 has a density of 1.55 g/cm³ (0.056 lb/in³), lighter than 56% of composite grades. Its glass-transition temperature is 110°C (230 °F). FR-2 has a tensile strength of 92 MPa (13.3 ksi), weaker than 71% of composite grades. Elongation at break is 1.1% and the elastic modulus is 7.5 GPa (1.09 Msi).
What is FR-2 used for?
- single-sided PCBs
- low-cost consumer electronics substrates
- general electrical insulation boards
Advantages
- Easy to machine — 75/100, better than 79% of composite grades
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
Limitations
- Needs corrosion protection — 48/100, worse than 94% of composite grades
- Low fracture toughness — 1.7 MPa·√m (1.55 ksi·√in), worse than 93% of composite grades
- Limited service temperature — 105°C (221 °F), worse than 90% of composite grades
- Degrades in UV without stabilisers — 25/100, worse than 86% of composite grades
- Limited ductility — 1.1%, worse than 78% of composite grades
FR-2 properties
Typical room-temperature values for FR-2-CCL-1S-35; bars are the position among composite grades.
Physical4
FR-2 has a density of 1.55 g/cm³ (0.056 lb/in³), lighter than 56% of composite grades. Its glass-transition temperature is 110°C (230 °F).
Mechanical11
FR-2 has a tensile strength of 92 MPa (13.3 ksi), weaker than 71% of composite grades. Elongation at break is 1.1% and the elastic modulus is 7.5 GPa (1.09 Msi).
Thermal9
FR-2 is rated for continuous service to 105°C (221 °F). It conducts heat at 0.35 W/m·K (0.202 BTU/hr·ft·°F), better than 50% of composite grades. Thermal expansion is 20 µm/m·K (11.1 µin/in·°F).
Electrical7
FR-2 is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10⁹ Ω·m.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 94% of composite grades. UV resistance is poor.
Sustainability4
Producing a kilogram of FR-2 takes about 85 MJ of energy and emits 4.5 kg of CO₂ — less than 79% of composite grades. Typical recycled content is 5%.
Manufacturability2
FR-2's machinability is very good (75/100, better than 79% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. FR-2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with FR-2
Is FR-2 easy to machine?
Blank, pierce and slot at room temperature with sharp shear-die tooling — this is FR-2's whole reason to exist; drill/rout with carbide, extract the abrasive paper dust and never plate the holes.
Can FR-2 be welded?
Not weldable — thermoset laminate; join mechanically with rivets, eyelets or screws, or bond with epoxy/cyanoacrylate.
Can FR-2 be formed, bent or molded?
Supplied fully cured and flat; cannot be post-formed or bent — design as flat blanks only, and bake before soldering if stored in humid conditions.
FR-2 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 |
|---|---|---|
| kraft cellulose paper (reinforcement)multiple plies of bleached/unbleached kraft | 42 – 58 | 50 |
| brominated flame retardanttetrabromobisphenol-A type or brominated phenolic | 3 – 10 | 6 |
| fillers / curing agents / pigments | 0 – 4 | 2 |
| electrodeposited copper foil (clad grade18/35/70 µm, additional to the laminate mass | ≈ 0 | 0 |
| phenol-formaldehyde (resole/novolac) resmatrix, may be epoxy-modified | ≥ 33 (balance) |
What surface finishes work on FR-2?
Copper is protected by HASL, OSP or roller-tinning; edges seal well with lacquer or conformal coat to limit moisture wicking into the paper core.
Equivalent designations
Standards and trade names that resolve to FR-2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- D709 Grade FR-2D709 Type FR-2
- Also called
- NEMA FR-2
How much does FR-2 cost?
FR-2 is a standard-cost composite ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
FR-2 — frequently asked
What is FR-2 used for?
FR-2 is typically used for single-sided PCBs, low-cost consumer electronics substrates and general electrical insulation boards. In short: cheapest punchable PCB substrate; cold-punchable phenolic paper; single-sided boards only.
What is the tensile strength of FR-2?
FR-2 has a typical tensile strength of 92 MPa (13.3 ksi) — weaker than 71% of composite grades. Strength varies by condition: see the 6 listed tempers.
Is FR-2 easy to machine?
Yes — machinability is rated very good (75/100, better than 79% of composite grades). Blank, pierce and slot at room temperature with sharp shear-die tooling — this is FR-2's whole reason to exist; drill/rout with carbide, extract the abrasive paper dust and never plate the holes.
Can FR-2 be welded?
Not weldable — thermoset laminate; join mechanically with rivets, eyelets or screws, or bond with epoxy/cyanoacrylate.
What surface finishes work on FR-2?
Copper is protected by HASL, OSP or roller-tinning; edges seal well with lacquer or conformal coat to limit moisture wicking into the paper core.
Can FR-2 be formed, bent or molded?
Supplied fully cured and flat; cannot be post-formed or bent — design as flat blanks only, and bake before soldering if stored in humid conditions.
What is the maximum service temperature of FR-2?
FR-2 is rated for continuous use to about 105°C (221 °F), and briefly to 260°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does FR-2 cost?
FR-2 is a standard-cost composite ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM D709 Standard Specification for Laminated Thermosetting Materials (Grade FR-2) — ASTM International (2017)
- NEMA LI 1 Industrial Laminated Thermosetting Products — NEMA (1998)
- IPC-4101 Specification for Base Materials for Rigid and Multilayer Printed Boards — IPC (2021)
- Engineered Materials Handbook Vol. 2 — Engineering Plastics (laminates section) — ASM International (1988)
- Paper-phenolic copper-clad laminate (FR-2 / XPC) technical data — Kingboard / Nan Ya Plastics / (2023)
- UL 796 / UL 746E Yellow Card listings for FR-2 copper-clad laminates — UL Solutions (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.