Common Basic Concept in PCB Design
FR4 sheet is a glass fiber epoxy resin coating plate, a substrate in a circuit board, which can be divided into general FR4 plates and high Tg FR4 sheets, and Tg is a glass conversion temperature, i.e., melting point. The circuit board must be flame-resistant and cannot be burned at a certain temperature, only can be soften. At this time, the temperature point is called the glass transformation temperature (TG point), which is related to the size stability of the PCB board.