XX FR-2
Flame-retardant grade
ASTM D709 Grade XX
FR-2 = flame-retardant paper-phenolic, UL 94 V-0
Specify when a V-0 rating is mandatory (consumer electronics, appliance insulation) in a paper-phenolic price class.
Values for the FR-2 condition
Other XX grades and fills
XX is listed in 7 conditions; see the grade overview at XX.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Thin cold-punch paper-phenolic | Thin-sheet grade that cold-punches cleanly at 0.8–1.6 mm; historic single-sided PCB substrate. | — | 85 | 2 | 95 HRM |
Cold-punching mechanical paper-phenolic | Use where room-temperature punching of gaskets/washers is the priority and electrical values are secondary. | — | 90 | 2 | 95 HRM |
FR-2This page Flame-retardant paper-phenolic, UL 94 V-0 | Specify when a V-0 rating is mandatory (consumer electronics, appliance insulation) in a paper-phenolic price class. | — | 95 | 1.8 | 100 HRM |
Hot-punching paper-phenolic | Choose when thin blanks must be punched at 80–130 °C without cracking, while keeping near-XX insulation values. | — | 105 | 1.7 | 100 HRM |
High-electrical punching grade paper-phenolic | Best combination of low dielectric loss and clean punching; classic terminal-board and coil-form material. | — | 105 | 1.6 | 100 HRM |
High-humidity electrical paper-phenolic | Pick for radio-frequency / high-humidity insulation where lower loss and lower moisture pickup matter more than strength. | — | 110 | 1.4 | 105 HRM |
XXDefault General-purpose mechanical/electrical paper-phenolic sheet | Default machining grade: best balance of strength, electrical properties and cost for milled or drilled insulation parts. | — | 120 | 1.5 | 105 HRM |
What is XX FR-2?
XX FR-2 is XX in the FR-2 grade — specify when a V-0 rating is mandatory (consumer electronics, appliance insulation) in a paper-phenolic price class. XX FR-2 has a tensile strength of 95 MPa (13.8 ksi), weaker than 69% of composite grades. Elongation at break is 1.8% and the elastic modulus is 7 GPa (1.02 Msi). XX FR-2 has a density of 1.35 g/cm³ (0.0488 lb/in³), lighter than 75% of composite grades. Its glass-transition temperature is 145°C (293 °F). XX is the default condition FabDigit quotes; FR-2 is available on request or by drawing note.
Advantages
- Easy to machine — 84/100, better than 90% of composite grades
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
- Lightweight — 1.35 g/cm³ (0.0488 lb/in³), better than 75% of composite grades
Limitations
- Low fracture toughness — 1.9 MPa·√m (1.73 ksi·√in), worse than 88% of composite grades
- Limited service temperature — 110°C (230 °F), worse than 87% of composite grades
- Degrades in UV without stabilisers — 25/100, worse than 86% of composite grades
- Absorbs moisture — dry before molding — 1.5%, worse than 81% of composite grades
- Needs corrosion protection — 60/100, worse than 79% of composite grades
XX FR-2 properties
Typical room-temperature values for XX FR-2; 19 are specific to this condition. Other listed values are XX reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
XX FR-2 has a density of 1.35 g/cm³ (0.0488 lb/in³), lighter than 75% of composite grades. Its glass-transition temperature is 145°C (293 °F).
Mechanical12
XX FR-2 has a tensile strength of 95 MPa (13.8 ksi), weaker than 69% of composite grades. Elongation at break is 1.8% and the elastic modulus is 7 GPa (1.02 Msi).
Thermal8
XX FR-2 is rated for continuous service to 110°C (230 °F). It conducts heat at 0.26 W/m·K (0.15 BTU/hr·ft·°F), worse than 71% of composite grades. Thermal expansion is 25 µm/m·K (13.9 µin/in·°F).
Electrical7
XX FR-2 is an electrical insulator with a dielectric strength of 13 kV/mm (330.2 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 79% of composite grades. UV resistance is poor.
Sustainability3
Producing a kilogram of XX FR-2 takes about 80 MJ of energy and emits 4.5 kg of CO₂ — less than 84% of composite grades. Typical recycled content is 0%.
Manufacturability2
XX FR-2's machinability is very good (84/100, better than 90% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with XX FR-2
Is XX easy to machine?
Cuts, drills and taps easily with carbide tooling and high rake; dust is abrasive and irritating, so use vacuum extraction and back-up plates to avoid exit-side delamination.
Can XX be welded?
Not weldable — thermoset; join by bolting, riveting or epoxy/phenolic adhesive bonding after abrasion and solvent wipe.
Can XX be formed, bent or molded?
Supplied fully cured and cannot be post-formed; blanking is done by punching (warm the sheet to 80–130 °C for XX/XXP, room temperature only for XP/XPC/thin stock).
What surface finishes work on XX?
Sanded or scraped to thickness; edges deburr readily; may be sealed with varnish or epoxy to limit moisture pickup, but plating and anodizing do not apply.
XX 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 |
|---|---|---|
| cellulose paper (kraft/alpha) reinforcemlayered paper webs, resin-impregnated | 45 – 60 | 55 |
| processing aids / plasticizer / release | 0 – 3 | 2 |
| phenol-formaldehyde (resole/novolac) resthermoset matrix, fully cured | ≥ 38 (balance) | — |
XX FR-2 — frequently asked
What is XX FR-2 used for?
XX FR-2 is typically used for punched insulating washers, terminal strips and low-voltage PCB substrates. In short: cleanest-punching paper phenolic; pre-FR-4 board material; low-cost punched insulation.
What is the tensile strength of XX FR-2?
XX FR-2 has a typical tensile strength of 95 MPa (13.8 ksi) — weaker than 69% of composite grades. Strength varies by condition: see the 7 listed tempers.
Is XX FR-2 easy to machine?
Yes — machinability is rated very good (84/100, better than 90% of composite grades). Cuts, drills and taps easily with carbide tooling and high rake; dust is abrasive and irritating, so use vacuum extraction and back-up plates to avoid exit-side delamination.
Can XX FR-2 be welded?
Not weldable — thermoset; join by bolting, riveting or epoxy/phenolic adhesive bonding after abrasion and solvent wipe.
What surface finishes work on XX FR-2?
Sanded or scraped to thickness; edges deburr readily; may be sealed with varnish or epoxy to limit moisture pickup, but plating and anodizing do not apply.
Can XX FR-2 be formed, bent or molded?
Supplied fully cured and cannot be post-formed; blanking is done by punching (warm the sheet to 80–130 °C for XX/XXP, room temperature only for XP/XPC/thin stock).
What is the maximum service temperature of XX FR-2?
XX FR-2 is rated for continuous use to about 110°C (230 °F), and briefly to 150°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM D709 — Standard Specification for Laminated Thermosetting Materials — ASTM International (2017)
- NEMA LI 1 — Industrial Laminated Thermosetting Products — NEMA (1998)
- Paper-phenolic laminate grade data (XX, XXP, XXX, XXXP, XPC) — Norplex-Micarta (2022)
- Engineered Materials Handbook, Vol. 2: Engineering Plastics — ASM International (1988)
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.