FR4 Epoxy Laminate and prepreg
FR-4 (or FR4) is a NEMA grade designation for glass-reinforced epoxy laminate material. FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing).
FR4 is the most popular PCB substrate material in the world. The denotation ‘FR4’ describes a class of materials that meet certain requirements defined by NEMA LI 1-1998 standards. FR4 materials have good thermal, electrical, and mechanical characteristics, as well as a favorable strength-to-weight ratio that makes them ideal for most electronic applications. FR4 laminates and prepreg are made from glass cloth, epoxy resin, and are usually the lowest cost PCB material available. It is especially popular for PCBs with lower layer counts – single, double sided into multilayered constructions generally less than 14 layers. Additionally, the base epoxy resin can be blended with additives that can significantly improve its thermal performance, electrical performance, and UL flame survival/rating – greatly improving its ability to be used in higher layer count builds, higher thermal stress applications, and greater electrical performance at a lower cost for high speed circuit designs. FR4 laminates and prepregs are very versatile, adaptable with widely accepted manufacturing techniques with predictable yields.