1. The components are arranged in disorder.
2. The polarity direction consistency is not good.
3. The layout design of chip components does not meet the requirements of wave soldering.
4. The pitch of components is too small, easily continuous welding.
5. PCB is placed with less than 0603, the component spacing is less than or equal to 0.63mmQFP, the castle package, the socket height is higher than 3.2mm and glass package diodes and other components.
6. There are many metallized vias with a hole diameter greater than 0.4mm at the bottom.
7. No specific soldering is done in certain areas.
8. The component spacing is less than 1mm or the visible pad angle is less than 45°affecting the components placement, visual inspection, welding, rework and other operations.