FR-4 is a flame retardant material grade code, representing a composite material based on epoxy resin and glass fiber cloth, which is widely used in PCB manufacturing and electronic insulation.

FR-4 is a key material widely used in the electronics industry. Its core characteristics and applications are as follows:

1. Definition and essence

• Material grade rather than specific name: FR-4 is a flame retardant grade code established by NEMA (National Electrical Manufacturers Association), indicating that the resin is epoxy resin, the reinforcement material is glass fiber cloth, and the flame retardant grade reaches UL94 V-0 standard.

• Composition: It is mainly composed of four-functional epoxy resin, filler (Filler) and electronic grade glass fiber cloth, and is made by high temperature and high pressure lamination process.

2. Key features

• Flame retardancy: Meets UL94 V-0 standard and can self-extinguish when burning.

• Electrical performance: Stable dielectric constant (Dk) (e.g. 4.5), excellent insulation, suitable for high-frequency circuits.

• Mechanical strength: High rigidity, heat resistance and moisture resistance, can be precisely processed.

• Thermal management: Low coefficient of thermal expansion (CTE), suitable for high temperature environments.

3. Application areas

• PCB manufacturing: As the mainstream substrate, it is used for multi-layer circuit boards (such as four-layer LED driver boards) to provide electromagnetic compatibility and current carrying capacity.

• Insulation components: including transformer insulation boards, motor insulation parts, FPC reinforcement boards, etc.

• Industrial equipment: such as grinding gears, testing boards, etc., which require high mechanical strength.