1. Substrate processing problems, for some thinner pcb substrates, due to poor rigidity of the substrate, it is not appropriate to use the brush machine to brush the board, and attention should be paid to control the solid production and processing, so as not to cause the poor bonding force between the substrate copper foil and chemical copper caused by the board bubbling.

　　2. The surface of the plate in the machining (drilling, laminating, milling, etc.) process caused by oil, or other liquids contaminated with dust pollution surface, will cause the surface foaming phenomenon.

　　3. The copper brush plate is bad, the grinding plate pressure is too large before copper sinking, resulting in hole deformation, so that the hole foaming phenomenon will be caused in the process of copper plating and tin-spraying welding.

　　4. Washing problem, due to copper plating to go through a large number of chemical solution treatment, all kinds of acid and alkali inorganic, organic and other drug solvents, not only will cause cross pollution, but also may cause local poor treatment of the board, resulting in some problems in binding force.

　　5. The micro-corrosion in the pre-treatment of copper sedimentation and the pre-treatment of graphic electroplating, excessive micro-corrosion will cause the hole to leak the substrate, resulting in the foaming phenomenon around the hole, and the activity of the copper sedimentation liquid is too strong, and the content of the three major components in the newly opened cylinder or tank of the copper sedimentation liquid is high, resulting in the defects of the physical quality of the coating and poor bonding force.

　　6. The surface oxidizes during the production process, which will also cause the surface to bubble.

　　7. Poor copper rework, some copper rework board in the rework process, because of poor fading plating, rework method or improper control of micro-corrosion time in the rework process will cause foaming.