Double-sided PCB as thin as 0.6mm

- Aug 31, 2018-

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What Is FR4 Material?

FR4, also written as FR-4, is both a name and a rating. The name is applied to the fiberglass-reinforced epoxy-laminated sheets used in printed circuit board manufacturing. However, the name also functions as a grade used to rate epoxy laminate sheets. The designation essentially indicates the base quality of a laminate sheet, meaning a variety of sheet materials and designs fall under the FR4 rating. The “FR” in the name stands for flame retardant, while the 4 differentiates the material from others of the same class.

The material widely referred to as FR4 is a composite structure. The most basic layer of the material is fiberglass woven into a thin, cloth-like sheet. The fiberglass gives FR4 its necessary structural stability. This innermost fiberglass layer is then surrounded and bound by a flame-resistant epoxy resin. This resin is what gives the material rigidity, among its other physical properties.

FR4 sheets are widely popular among electrical engineers and designers as a PCB base material. The low cost and versatility of the material, as well as its wealth of beneficial physical properties, accounts for that popularity. FR4 sheets are electrical insulators with high dielectric strength. They also feature a high strength-to-weight ratio and are lightweight and resistant to moisture. Add this to their relative temperature resistance, and FR4 can perform well in most environmental conditions.