What is the difference between epoxy resin board and epoxy glass cloth board?

FR-4 is the code name of a flame-resistant material grade. It represents a material specification that the resin material must be able to extinguish by itself after burning. It is not a material name, but a material grade. Therefore, the current general circuit There are many types of FR-4 grade materials used in the board, but most of them are composite materials made of so-called Tera-Function epoxy resin, Filler and glass fiber.