FR-4 classification: The surface colors of FR-4 epoxy glass cloth laminate are include: Yellow FR-4, white FR-4, black FR-4, blue FR-4, etc. FR-4 is a type of sheet and used for PCB as the substrate. According to the different of reinforcement materials, the FR4 sheets are mainly classified into the following four types: 1) FR-4: glass cloth substrate 2) FR-1, FR-2, etc.: paper substrate 3) CEM series: composite substrate 4) Special material substrate (ceramic, metal base, etc.) FR-4 is a laminate board that obtained by immersing epoxy resin with alkali-free glass fiber cloth by pressing under high-temperature and high-pressure,it’s rigid insulating laminated sheet. Features: High mechanical and dielectric properties, good heat and moisture resistance and good machinability. Uses: Insulation structural parts in motors and electrical equipment, including various types of switches FPC reinforced, electrical insulating carbon film printed circuit boards, computer drillin...