Each company has some differences in the design of materials. Generally, the definition of materials focuses on the setting of the glass transition point. But for the long-term temperature resistance, it is only necessary to meet the standard, so the quality requirements in this regard are all Different. For long-term temperature resistance, most FR-4 materials should be able to withstand a high temperature of about 120 degrees for a long time. However, the glass transition point of general solder resist paint will fall at about 110 degrees. Therefore, if the high temperature parts are assembled ( SMD) on the circuit board surface, it is best to pay attention to its heat dissipation state, so as to ensure the long-term stable state of the electronic product and not damage the structure of the circuit board.