For - like electronic products using FR4 epoxy fiberglass substrate, or for the use of high ambient temperature polyimide flexible circuit board with fiberglass substrate is required for high-frequency circuits with PTFE fiberglass substrate; For cooling requirements of high electronic products should be used metal substrates.
When selecting PCB materials considerations:
(1) should be selected glass transition temperature (Tg) higher substrate, Tg should be higher than the circuit operating temperature.
(2) requires the coefficient of thermal expansion (CTE) is low. Since the X, Y, and coefficient of thermal expansion in the thickness direction is inconsistent, PCB likely to cause deformation, can cause severe breakage and damage to the metal hole components.
(3) high heat resistance is required. General requirements for PCB can have 250 ℃ / 50S heat resistance.
(4) requires good flatness. SMT of PCB warpage requirements <0.0075mm/mm.
(5) electrical performance, high-frequency circuit requires to select high dielectric constant material having a small dielectric loss. Insulation resistance, breakdown voltage, arc resistance must meet product requirements.
