FR-4 is a designation for a flame-retardant material grade, meaning that the resin material must be able to self-extinguish after being burned. It is not a material name, but a material grade. Therefore, there are many types of FR-4 grade materials used in general circuit boards, but most of them are composite materials made of so-called four-function epoxy resin, filler, and glass fiber.
FR-4 Classification:
FR-4 epoxy glass cloth laminate surface colors include: Yellow FR-4, White FR-4, Black FR-4, Blue FR-4, etc.
FR-4 is a substrate used in PCBs, a type of board material. Board materials are mainly classified into the following four types according to the reinforcing material:
1) FR-4: Glass cloth substrate
2) FR-1, FR-2, etc.: Paper substrate
3) CEM series: Composite substrate
4) Special material substrates (ceramic, metal, etc.) FR-4 is a plate-shaped laminate product made by impregnating special electronic cloth with epoxy phenolic resin and other materials, and then hot-pressing it under high temperature and pressure.
Features: High mechanical and dielectric properties, good heat and moisture resistance, and good machinability.
Applications: Used as insulating structural components in motors and electrical equipment, including various types of switch FPC reinforcement, electrical insulation carbon film printed circuit boards, computer drilling pads and molds (PCB test fixtures), and can be used in humid environments and transformer oil.
Basic Characteristics
Vertical Layer Bending Strength A: Normal state: E-1/150, 150±5℃ ≥340Mpa
Parallel Layer Impact Strength (Simply Supported Beam Method): ≥230KJ/m
Insulation Resistance After Immersion (D-24/23): ≥5.0×10⁸Ω
Vertical Layer Electrical Strength (in transformer oil at 90±2℃, plate thickness 1mm): ≥14.2MV/m
Parallel Layer Breakdown Voltage (in transformer oil at 90±2℃): ≥40KV
Relative Permittivity (…) 50Hz: ≤5.5
Relative permittivity (1MHz): ≤5.5
Dielectric loss factor (50Hz): ≤0.04
Dielectric loss factor (1MHz): ≤0.04
Water absorption (D-24/23, plate thickness 1.6mm): ≤19mg
Density: 1.70-1.90g/cm³
Flammability: FV0
Process characteristics
(1) Melting point of FR-4 process platen (203℃)
(2) High chemical resistance
(3) Low loss factor (Df) 0.0025)
(4) Stable and low dielectric constant (Dk 2.35)
(5) Thermoplastic material
What is FR-4?
FR-4 is a designation for a flame-retardant material grade. It represents a material specification where the resin material must be self-extinguishing after combustion. It is not a material name, but a material grade. Therefore, there are many types of FR-4 grade materials used in general circuit boards, but most are composite materials made of so-called four-function (tera-function) epoxy resin plus filler and glass fiber.
FR-4 epoxy glass cloth laminate, depending on its application, is generally referred to in the industry as: FR-4 Epoxy Glass Cloth, insulating board, epoxy board, epoxy resin board, brominated epoxy resin board, FR-4, glass fiber board, fiberglass board, FR-4 reinforcing board, FPC reinforcing board, flexible circuit board reinforcing board, FR-4 epoxy resin board, flame-retardant insulating board, FR-4 laminate, epoxy board, FR-4 plain board, FR-4 fiberglass board, epoxy glass cloth board, epoxy glass cloth laminate, and circuit board drilling pad. Main technical features and applications: Electrical insulation [1] is stable, flat, smooth, without pits, and has standard thickness tolerance. It is suitable for products with high-performance electronic insulation requirements, such as FPC reinforcing boards, PCB drilling pads, glass fiber spacers, potentiometer carbon film printed glass fiber boards, precision planetary gears (wafer grinding), precision test boards, electrical (electrical) equipment insulation support strips, insulation pads, transformer insulation boards, motor insulation parts, grinding gears, electronic switch insulation boards, etc.
