For general electronic products, FR4 epoxy glass fiber substrate is used, for high ambient temperature or flexible circuit boards, polyimide fiberglass substrates are used, and for high-frequency circuits, PTFE fiberglass substrates are required; Electronic products with high heat dissipation requirements should use metal substrates.

　　(1) A substrate with a higher glass transition temperature (Tg) should be appropriately selected, and the Tg should be higher than the operating temperature of the circuit.

　　(2) The coefficient of thermal expansion (CTE) is required to be low. Due to the inconsistency of the thermal expansion coefficients in the X, Y, and thickness directions, it is easy to cause PCB deformation, and in severe cases, the metallized hole will break and the components will be damaged.

　　(3) High heat resistance is required. Generally, PCBs are required to have a heat resistance of 250°C/50S.

　　(4) Good flatness is required. The SMT PCB warpage requirement is "0.0075mm/mm.

　　(5) In terms of electrical performance, high-frequency circuits require materials with high dielectric constant and low dielectric loss. Insulation resistance, withstand voltage strength, and arc resistance must meet product requirements.

　　 The above are the factors that should be considered when selecting PCB materials, so remember to take them into consideration next time you choose.