In the PCBA assembly process, the board surface bonding force is poor, that is to say, the surface quality of the board surface is problematic, which will cause the circuit board surface to bubble, which contains two aspects: one is the cleanliness of the board; the other is On the one hand, there is the problem of surface micro-roughness (or surface energy). Basically all the blistering problems on the circuit board can be summarized into these two reasons.

The problem of poor board adhesion is mainly reflected in the poor or too low adhesion between the coatings, because it is difficult to resist the coating stress, mechanical stress and thermal stress generated during the production process during the subsequent production process and PCBA assembly process. And so on, causing it to cause different degrees of separation between the plating.

So what are the factors that affect the surface quality of the board in the PCBA production process and PCBA assembly process?

The problem of substrate processing: especially for some thinner substrates (generally less than 0.8mm), because the rigidity of the substrate is poor, it is not suitable to use a brushing machine to brush the plate. 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 kind of problem will also cause blackening and browning when the thin inner layer is blackened. Poor, uneven color, partial black browning and other problems.

Insufficient water washing after development during the image transfer process: too long after development or too much dust in the workshop, etc., will cause poor cleanliness of the board surface, and a slightly poor fiber processing effect may cause potential quality problems.

The surface of the board is oxidized during the production process: if the immersion copper plate is oxidized in the air, it may not only cause no copper in the hole and rough board surface, but also may cause blistering on the board surface; the immersion copper plate may be stored in acid for too long , The board surface will also be oxidized, and this oxide film is very difficult to remove; therefore, during the production process, the heavy copper plate should be thickened in time, and it is not suitable to store it for too long. Generally, the thickened copper plating should be completed within 12 hours at the latest.

The pickling tank before copper plating should not be replaced in time: there is too much pollution in the bath or the copper content is too high, and the pickling tank before copper plating should be replaced in time, otherwise it will not only cause the cleanliness of the board, but also cause the board to be rough. And other defects.

Washing problem: As the electroplating of heavy copper requires a lot of chemical treatment, there are many chemical solvents such as acid, alkali, non-polar organic, etc., and the surface of the board is not clean with water, especially the heavy 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 bonding problems in PCBA assembly; therefore, attention should be paid to strengthening the control of washing, mainly including the flow of cleaning water and water quality. , Washing time, and panel dripping time; 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.

The above content is a common cause of blistering on the board surface in the actual circuit board production and PCBA circuit board assembly process. In addition, there are many reasons for the blistering of the board. Different manufacturers may have blistering caused by different reasons due to the difference in equipment technology. Therefore, it is necessary to combine the actual situation and analyze the specific problems in detail.