PCB News - Causes of blistering on the surface of the copper-immersed electroplated circuit board

Board surface blistering is one of the more common quality defects in the circuit board production process, because the complexity of the circuit board production process and the complexity of the process maintenance, especially in the chemical wet treatment, make the prevention of the board surface blistering defect comparison difficulty. Next, let's analyze what causes this phenomenon.

1. The problem of substrate processing; especially for some thin substrates, (usually below 0.8mm), because the substrate has poor rigidity, it is not suitable to use a brushing machine to brush the substrate, which may not be able to effectively remove the substrate production and processing In the process, the protective layer specially treated to prevent the oxidation of the copper foil on the board surface. Although the layer is thin and easy to remove by brushing, it is more difficult to use chemical treatment. Therefore, it is important to pay attention to control in the production and processing to avoid causing the board surface. The problem of blistering on the board surface caused by the poor bonding force between the base material copper foil and chemical copper; this problem will also have poor blackening and browning when the thin inner layer is blackened, uneven color, and local black brown The problem is not superior.

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 hole to be deformed, brushing out the hole copper foil rounded corners or even the hole leaking the substrate, which will cause the sinking copper electroplating, spraying and soldering, etc. 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, 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 processing of the circuit board surface or poor processing effect, uneven defects, and cause some bonding problems; therefore, it is necessary to strengthen the control of washing, mainly including the flow of cleaning water, water quality, The washing time and the dripping time of the panel are controlled; especially in winter, the temperature is lower, the washing effect will be greatly reduced, and more attention should be paid to the control of the washing.

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