PCB Technical - What are the reasons for blistering on the PCB surface?

What are the reasons for blistering on the PCB surface?
From the poor bonding force of the board surface, the surface quality problems of the board surface are divided into:
1. The cleanliness of the board surface
2. The problem of surface micro-roughness (or surface energy).
PCB circuit board proofing Youke board summarizes the poor quality of the board surface that may be caused during the production and processing process and is divided into:
1. The problem of substrate process processing: especially for some thin substrates (generally below 0.8mm), because the substrate has poor rigidity, it is not suitable to use a brushing machine to brush the board. This may not be able to effectively remove the protective layer specially treated to prevent the oxidation of the copper foil on the board surface during the production and processing of the substrate. Although the layer is thin and the brush is easier to remove, it is more difficult to use chemical treatment, so in production It is important to pay attention to control during processing, so as to avoid the problem of blistering on the board caused by the poor bonding between the copper foil of the board substrate and the chemical copper; this problem will also cause blackening and browning when the thin inner layer is blackened. Poor, uneven color, partial black browning and other problems.

2. The phenomenon of poor surface treatment caused by oil stains or other liquids contaminated with dust during the machining (drilling, lamination, milling, etc.) process of the board surface.
3. Poor sinking copper brush plate: the pressure of the sinking copper front grinding plate is too large, causing the orifice to be deformed, brushing out the copper foil rounded corners of the orifice or even leaking the substrate, which will cause the sinking copper electroplating, spraying tin welding and other processes. Foaming phenomenon at the orifice; even if the brush plate does not cause leakage of the substrate, the excessively heavy brush plate will increase the roughness of the orifice copper, so the copper foil at this place is likely to be over-roughened during the micro-etching roughening process, There will also be certain quality hidden dangers; therefore, attention should be paid to strengthening the control of the brushing process, and the brushing process parameters can be adjusted to the best through the wear scar test and the water film test.
4. Water washing problem: Because the electroplating treatment of copper sinking has to go through a lot of chemical treatment, various kinds of acid, alkali, non-polar organic and other pharmaceutical solvents are more, and the surface of the board is not clean with water, especially the sinking copper adjustment degreasing agent, which will not only cause cross-contamination At the same time, it will also cause poor local treatment of the board surface or poor treatment effect, uneven defects, and cause some binding problems; therefore, attention should be paid to strengthening the control of washing, mainly including the flow of washing water, water quality, and washing time., And the control of the dripping time of the panel; especially in winter, the temperature is lower, the washing effect will be greatly reduced, and more attention should be paid to the strong control of the washing
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