XXX
Grade · default condition
ASTM D709 Grade XXX, D709 Type XXX · GB 3025
XXX = standard high-electrical paper-phenolic laminate
Pick for the best moisture and 1 MHz loss performance in the paper-base series where parts are machined, not punched.
Values for the XXX condition
Other XXX grades and fills
XXX is listed in 4 conditions; see the grade overview at XXX.
Compare all 4 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Cold-punchable high-electrical paper-phenolic | Choose when thin parts must be punched at room temperature without pre-heat; slightly lower stiffness and higher moisture pickup than XXX. | — | 95 | 1.6 | 95 HRM |
Hot-punchable high-electrical paper-phenolic | Same electrical class as XXX but formulated to punch cleanly when pre-heated (~90–130 °C); use for stamped washers and terminal strips. | — | 100 | 1.5 | 100 HRM |
Flame-retardant paper-phenolic | Flame-retardant version of the punchable paper-phenolic family, the classic single-sided copper-clad PCB substrate; use where UL 94V-0 is required. | — | 100 | 1.4 | 100 HRM |
XXXDefaultThis page Standard high-electrical paper-phenolic laminate | Pick for the best moisture and 1 MHz loss performance in the paper-base series where parts are machined, not punched. | — | 110 | 1.3 | 105 HRM |
What is XXX?
XXX is XXX in the XXX grade — pick for the best moisture and 1 MHz loss performance in the paper-base series where parts are machined, not punched. XXX has a tensile strength of 110 MPa (16 ksi), weaker than 64% of composite grades. Elongation at break is 1.3% and the elastic modulus is 8 GPa (1.16 Msi). XXX has a density of 1.36 g/cm³ (0.0491 lb/in³), lighter than 70% of composite grades.
Advantages
- Low embodied carbon — 4.5 kg CO₂/kg, better than 79% of composite grades
Limitations
- Low fracture toughness — 1.6 MPa·√m (1.46 ksi·√in), worse than 95% of composite grades
- Needs corrosion protection — 60/100, worse than 79% of composite grades
- Limited service temperature — 120°C (248 °F), worse than 78% of composite grades
- Poor heat conductor — 0.25 W/m·K (0.144 BTU/hr·ft·°F), worse than 76% of composite grades
- Hard to polish — 25/100, worse than 76% of composite grades
XXX properties
Typical room-temperature values for XXX; 19 are specific to this condition. Other listed values are XXX reference data and may not represent this condition. Bars are the position among composite grades.
Physical3
XXX has a density of 1.36 g/cm³ (0.0491 lb/in³), lighter than 70% of composite grades.
Mechanical13
XXX has a tensile strength of 110 MPa (16 ksi), weaker than 64% of composite grades. Elongation at break is 1.3% and the elastic modulus is 8 GPa (1.16 Msi).
Thermal8
XXX is rated for continuous service to 120°C (248 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), worse than 76% of composite grades. Thermal expansion is 22 µm/m·K (12.2 µin/in·°F).
Electrical7
XXX is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10¹¹ 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 XXX takes about 95 MJ of energy and emits 4.5 kg of CO₂ — less than 72% of composite grades. Typical recycled content is 0%.
Manufacturability2
XXX's machinability is good (60/100, better than 73% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with XXX
Is XXX easy to machine?
Saws, drills and mills readily with sharp carbide tooling and high speed/low feed; dust is abrasive and irritating so use extraction, and back up thin sheet to avoid edge delamination.
Can XXX be welded?
Thermoset — cannot be welded; join by mechanical fasteners or epoxy/phenolic adhesives after abrading and degreasing the surface.
Can XXX be formed, bent or molded?
Supplied as fully cured flat sheet, rod or tube — no post-forming; standard XXX must be machined, while XXXP (hot punch, part pre-heated ~90–130 °C) or XXXPC (cold punch) are chosen for stamped parts.
What surface finishes work on XXX?
Edges should be sealed with varnish or epoxy to keep moisture out and preserve insulation resistance; can be painted after light abrasion, and no plating or anodizing applies.
XXX 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 |
|---|---|---|
| phenol-formaldehyde resinresole/novolac phenolic binder, may contain plasticiser and moisture-resist additives | 40 – 55 | 48 |
| residual volatiles / moisture | 0 – 1.5 | 0.5 |
| bleached cellulose kraft insulating papealpha-cellulose electrical grade paper webs | ≥ 45 (balance) | — |
XXX — frequently asked
What is XXX used for?
XXX is typically used for high-grade electrical insulation boards, transformer components and terminal insulation. In short: highest insulation resistance, paper-base; machining grade, not punchable; low-cost electrical laminate.
What is the tensile strength of XXX?
XXX has a typical tensile strength of 110 MPa (16 ksi) — weaker than 64% of composite grades. Strength varies by condition: see the 4 listed tempers.
Is XXX easy to machine?
Reasonably — machinability is rated good (60/100, better than 73% of composite grades). Saws, drills and mills readily with sharp carbide tooling and high speed/low feed; dust is abrasive and irritating so use extraction, and back up thin sheet to avoid edge delamination.
Can XXX be welded?
Thermoset — cannot be welded; join by mechanical fasteners or epoxy/phenolic adhesives after abrading and degreasing the surface.
What surface finishes work on XXX?
Edges should be sealed with varnish or epoxy to keep moisture out and preserve insulation resistance; can be painted after light abrasion, and no plating or anodizing applies.
Can XXX be formed, bent or molded?
Supplied as fully cured flat sheet, rod or tube — no post-forming; standard XXX must be machined, while XXXP (hot punch, part pre-heated ~90–130 °C) or XXXPC (cold punch) are chosen for stamped parts.
What is the maximum service temperature of XXX?
XXX is rated for continuous use to about 120°C (248 °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)
- IEC 60893-3-4 — Insulating materials, rigid laminated sheets, cellulose paper/phenolic (PF CP 201/202) — IEC (2013)
- Engineered Materials Handbook Vol.2 — Engineering Plastics — ASM International (1988)
- Industrial paper-phenolic laminate (XXX/XXXP/XXXPC) datasheets — Norplex-Micarta / Franklin Fibre / (2023)
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.