In PCB, IPC is divided into 1 level, level 2 and level 3. 1 general electronic consumer products. Special service electronic products. 3 High-performance electronic products. The higher the grade, the stricter the quality inspection requirements. No matter in PCB, there are three levels, such as the accuracy of drilling hole diameter, the thickness and flatness of copper plating in the hole, and the thickness of solder resist oil. , more and stricter than the tolerance range and inspection items of Grade 2. Products judged strictly at level 3, whether civilian or military, must ensure the uninterrupted characteristics of high stability and long life.