What are the causes of blisters on the PCB surface

- Aug 18, 2018-

From the problem of poor adhesion of the board surface, the surface quality of the board surface can be divided into:

1. Cleanliness of board surface;

2. The problem of surface roughness (or surface energy).

PCB sample making uke board may cause poor board quality in the process of production and processing, which can be divided into:

1. Problems of substrate processing: especially for some thin substrates (generally under 0.8mm), as the rigidity of the substrates is poor, it is not suitable to brush the plates with the 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 important to pay attention to control in the production processing, lest cause panel substrate copper foil and copper chemical bonding force between the surface bubbles caused by bad;When the thin inner layer is blackened, there will be some problems such as poor Browning, uneven color, and partial Browning.

2. Poor surface treatment caused by oil pollution or dust contamination of other liquids during machining (drilling, lamination, edge milling, etc.) of the board surface.

3. Bad quality of the heavy copper brush plate: excessive pressure on the grinding plate before the heavy copper plate is applied, resulting in the distortion of the hole mouth. Brush out the copper foil circular corner or even the hole mouth to leak the base material.Even if the brush plate does not cause the leakage of base material, the overweighted brush plate will increase the roughness of the copper orifice, so the copper foil in the process of micro-corrosion coarsening will easily produce excessive coarsening, and there will also be some quality hidden trouble.Therefore, it is necessary to strengthen the control of the brush plate process, which can adjust the brush plate process parameters to the best by grinding mark test and water film test.

4, washing problem: because heavy copper electroplating processing should pass a lot 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, the control of water washing should be strengthened, mainly including the control of water flow, water quality, water washing time, and water dripping time of plate parts.Especially in winter, when the temperature is low, washing effect will be greatly reduced