FR-4 is the most commonly used base material for printed circuit boards (PCBs). It is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing). The "FR" stands for Flame Retardant, and it meets the UL94V-0 standard for flammability.
The material is created by impregnating a glass fiber cloth with an epoxy resin. This combination results in a laminate that provides excellent mechanical strength, good electrical insulation properties, and high thermal resistance.
FR-4 is used as the insulating substrate for the vast majority of rigid and multi-layer PCBs. Its versatility makes it suitable for a wide range of electronic applications, from consumer electronics to industrial controls.
There are different grades of FR-4 material, which can vary in thermal performance (Tg - Glass Transition Temperature), dielectric constant, and other properties to suit specific application requirements.
FR-4 remains the industry standard for PCB substrates due to its balanced performance, reliability, and cost-effectiveness. Its properties make it an ideal choice for the majority of electronic circuit applications.
