FR-4 is the code of refractory grade, which means that the resin material must extinguish itself after burning. It is not a material name, but a material grade. Therefore, there are many kinds of FR-4 materials currently used in ordinary PCB, but most of them are composites made of the so-called Tera Function epoxy resin, filler and glass fiber.

FR-4 epoxy glass cloth laminate is generally called FR-4 epoxy glass cloth, insulating board, epoxy board, epoxy resin board, brominated ring resin board, FR-4, glass fiber board, FR-4 reinforcement board, FPC reinforcement board, flexible circuit board reinforcement board, FR-4 epoxy resin board, flame retardant insulation board, FR-4 laminate, etc. Main technical features and applications: no pits, thickness in line with tolerance standards, applicable to fiberglass media, potentiometers, carbon film printed fiberglass boards, precision planetary gears (grinding discs), precision test boards, electrical (electrical) equipment insulation support diaphragms, insulation pads, etc.