Circuit board surface bubbling is actually a problem of poor surface binding force, and then extended is the surface quality of the board, which contains two aspects:
1. The cleanliness of the board.
2. Surface micro roughness (or surface energy) problem.
All board surface bubbling problems on the PCB board can be summarized as the above causes.
The binding force between the coatings is poor or too low, and it is difficult to resist the coating stress, mechanical stress and thermal stress generated in the production and processing process in the subsequent production and assembly process, and finally cause the separation phenomenon of different degrees between the coatings.
1. The problem of base material processing
Especially for some thinner substrates (generally below 0.8mm), because the substrate rigidity is poor, it is not suitable to brush the plate machine. So may be unable to effectively remove the substrate in order to prevent the surface oxidation of copper foil in the process of production and processing and special processing layer, while the layer is thinner, brush plate is easy to remove, but the chemical processing is difficult, so the important note in production and processing control, lest cause panel substrate copper foil and copper chemical bonding force between the surface bubbles caused by bad; This problem in the thin inner layer of black, there will be bad black brown, uneven color, local black brown is not first-class problems.
2. the surface in machining (drilling, lamination, milling, etc.) caused by the process of oil or other liquid dust contaminated surface treatment of poor phenomenon.
3. Bad copper brush plate
The pressure of the grinding plate before copper precipitation is too large, resulting in deformation of the orifice, and the copper foil rounded corners and even the substrate leakage of the orifice are brushed out, so the orifice foaming phenomenon will be caused in the process of copper precipitation electroplating and tin-spraying welding. Even if the brush plate does not cause substrate leakage, the excessive brush plate will increase the roughness of copper at the mouth, so in the process of micro-etching and coarsening, the copper foil is easy to produce excessive coarsening phenomenon, and there will be a certain quality hidden trouble; Therefore, attention should be paid to strengthen the control of brush plate process, brush plate process parameters can be adjusted to the best through wear mark test and water film test.
4. Water washing
Want because of heavy copper electroplating processing through a large number of chemical liquid medicine processing, all kinds of acid-base the non-polar organic solvent such as drugs, board face wash not clean, especially heavy copper adjustment in addition to the agents, not only can cause cross-contamination, also will cause the board face local processing bad or poor treatment effect, the defect of uneven, cause some of the binding force; Therefore, we should pay attention to strengthen the control of water washing, mainly including the control of the flow of cleaning water, water quality, water washing time, and the dripping time of plates and other aspects; Especially in winter when the temperature is low, the effect of washing will be greatly reduced, and more attention should be paid to the control of washing.
