XX sheet is the flat-panel form of NEMA Grade XX paper-phenolic laminate — a thermoset composite produced by laminating kraft paper with phenolic resin under heat and pressure into rigid, lightweight flat stock. Grade XX is the standard mechanical-electrical paper-phenolic grade, offering low cost, easy machinability, and good electrical performance under low-humidity conditions, making XX sheet a popular choice for general-purpose insulating panels, terminal boards, and prototyping plates.
XX sheet delivers tensile strength of 14,000 psi, flexural strength of 16,000 psi, and compressive strength of 26,000 psi. Rockwell hardness reaches M105, shear strength is approximately 11,000 psi, and water absorption over 24 hours is approximately 3.5% — reflecting paper-phenolic’s sensitivity to humidity. The material carries a UL 94HB flammability rating and operates continuously up to 250°F (121°C). Dielectric strength is approximately 500 V/mil short-time at 1/16″ thickness perpendicular to laminations. These properties make XX sheet a low-cost choice for terminal boards, insulating panels, prototyping plates, and equipment back-panels in dry environments.
Standards & compliance. XX sheet conforms to NEMA LI-1 Grade XX and meets defense specification MIL-I-24768/12 (Type PBE). Test methods follow ASTM D709. Ready Plastics stocks XX sheet in a range of thicknesses; custom cuts are available through our cut-to-size service.
Sister grades. For better dielectric performance under humid conditions, step up to Grade XXX paper-phenolic sheet. For higher mechanical strength and impact resistance, Grade C cotton-phenolic sheet or Grade CE cotton-phenolic sheet are preferred. When mechanical strength, low water absorption, and high dielectric performance are needed, see G-10 glass-epoxy sheet or FR-4 glass-epoxy sheet.
