FR5 sheet is the flat-panel form of FR-5 glass-epoxy laminate — a flame-retardant, high-temperature thermoset composite produced by impregnating woven fiberglass cloth with a brominated epoxy resin and laminating the assembly under heat and pressure into rigid, dimensionally stable flat stock. FR-5 combines the 355°F (180°C) continuous-use rating of G-11 with UL 94 V-0 flame performance, making FR5 sheet the go-to grade for high-temperature electrical panels and Class H insulation where self-extinguishing behavior is required.
FR5 sheet delivers tensile strength of 40,000 psi, an excellent flexural strength of 70,000 psi, and compressive strength of 60,000 psi. Rockwell hardness reaches M110, shear strength is approximately 19,000 psi, and water absorption over 24 hours is just 0.10%. The material carries a UL 94 V-0 flammability rating and operates continuously up to 180°C. These properties make FR5 sheet a preferred choice for transformer barrier boards, switchgear panels, motor slot insulation, and high-voltage standoffs in Class H-rated equipment.
Standards & compliance. FR5 sheet conforms to NEMA LI-1 Grade FR-5 and is tested per ASTM D709. The flame-retardant rating is established under UL 94 V-0. Ready Plastics stocks FR5 sheet in a range of thicknesses and standard panel dimensions; custom cuts are available through our cut-to-size service.
Sister grades. For 180°C service without flame-retardant requirements, G-11 glass-epoxy sheet offers the same thermal class at lower cost. Where 140°C service is sufficient and V-0 flame performance is required, FR-4 glass-epoxy sheet is the standard choice. For arc resistance at high temperature, see G-7 glass-silicone sheet.
