Causes Of Bubble Of Board In PCBA Assembly

- Sep 08, 2017-

The following are possible in the PCB production and processing and PCBA assembly process caused by poor quality of some of the factors summarized.

1, the substrate process problems: In particular, for some of the thin substrate (generally 0.8mm below), because the substrate stiffness is poor, should not use brush board brush plate. This may not be able to effectively remove the substrate during the production process to prevent the plate copper foil oxidation and special treatment of the protective layer, although the layer is thin, easy to remove the brush, but the use of chemical treatment there is a big difficulty, Processing important attention control, so as not to cause the board substrate copper foil and chemical copper between the poor adhesion caused by the plate surface foaming problem; this problem in the thin inner layer of black, there will be blackening Bad, uneven color, local black brown is not on the issue.

2, the board in the machining (drilling, laminating, milling, etc.): in this process caused by oil or other liquid contamination of dust pollution caused by poor surface treatment.

3, Shen copper brush bad: Shen copper front plate pressure is too large, resulting in deformation of the orifice out of the mouth of the copper foil corners or even hole leakage substrate, so in the copper plating plating tin welding process will cause Hole blistering phenomenon; even if the brush plate does not cause leakage of substrate, but the heavy brush will increase the orifice of copper roughness, and thus in the micro-euthanization during the process of copper can easily produce over-rough phenomenon , There will be a certain quality hazard; so we should pay attention to strengthen the control of the brush plate process, through the wear test and water film test brush plate process parameters to adjust to the best.

4, washing problem: As the copper plating treatment to go through a large number of chemical treatment, so all kinds of acid and alkali and other organic solvents and more solvent, plate water is not clean, especially the copper adjustment of oil, not only will cause cross Pollution, but also cause poor processing of the board or poor handling, uneven defects, resulting in some PCBA assembly of the binding capacity of the problem; so pay attention to strengthen the control of the washing, including cleaning water flow , Water quality, washing time, and board drip time and other aspects of control; especially winter temperatures are low, washing effect will be greatly reduced, but also pay attention to the strong control of the washing.

5, Shen copper pretreatment and graphics plating in the pre-treatment of micro-eclipse: micro-erection should not be excessive, otherwise it will cause the hole leakage substrate, resulting in perforation around the bubble phenomenon; micro-corrosion will also cause insufficient joint strength, triggering Foaming phenomenon; therefore to strengthen the control of micro-erosion; general copper pretreatment of the micro-etching depth of 1.5 --- 2 microns, pre-treatment of micro-corrosion plating 0.3 --- 1 micron, the best conditions through the chemical Analysis and simple test Weighing method to control the thickness of micro-etching or erosion rate; under normal circumstances after the micro-corrosion of the board bright color, uniform pink, no reflection; if the color is not uniform, or reflective description of the process before the existence of quality Hidden trouble; pay attention to strengthen the inspection; another micro-etching tank copper content, bath temperature, load, micro-agent content, etc. are to pay attention to the project