Car Security System circuit board
The following are some of the factors that can contribute to poor board quality during PCB manufacturing and PCBA assembly.
1，the substrate processing problems: especially for some thinner substrates (generally 0.8mm below), because the substrate less rigid, should not be used brush plate machine.1, this may not be able to effectively remove the substrate during the production process to prevent oxidation of the surface of the copper foil and special protection layer, although this layer is thin, easy to remove the brush plate, but the use of chemical treatment there is a big difficulty, so Important attention to control in the production and processing, so as not to cause the surface of the substrate copper foil and the poor bonding between the board caused by foaming problems; this problem in the thin inner layer of black, there will be black , Poor browning, uneven color, partial dark brown not on the issue.
2, the board in the machining (drilling, laminating, milling, etc.): In the process caused by oil or other liquid contaminated with dust pollution surface treatment is not good.
3, bad copper brush plate: copper before grinding plate pressure is too large, resulting in distortion of the hole brush hole copper foil or even orifice leakage of the substrate, so in the process of copper plating tin spray welding will result in Hole blisters phenomenon; even if the brush does not cause leakage of substrate, but excessive brush will increase the rough copper aperture, and therefore roughening in the process of micro-roughening prone to excessive roughening phenomenon , There will be some hidden dangers of quality; therefore, we should pay attention to strengthening the control of the brush plate process, and can adjust the brush plate process parameters to be the best through the abrasion test and the water film test.
4, the problem of washing: Because the copper plating process to go through a lot of chemical treatment, so all kinds of acid-base electrodeless organic solvents and other drugs more, the board is not washed, especially copper adjustment degreaser, not only will cause cross Pollution, at the same time will also result in poor processing of the board surface or poor treatment, uneven defects, resulting in some binding force in the PCBA assembly problems; therefore, we should pay attention to strengthen the control of the washing, including the cleaning water flow , Water quality, washing time, and board dripping time and other aspects of control; special winter temperatures are lower, the washing effect will be greatly reduced, but also pay attention to the strong control of the washing.
5. Per-treatment of copper plating and micro-etching in pre-treatment of pattern plating: Micro-erosion should not be excessive, otherwise it will cause leakage of the substrate, resulting in foaming phenomenon around the orifice; Under-etching will also result in insufficient binding force, causing Foaming phenomenon; Therefore, to strengthen the control of micro-etching; general immersion copper per-treatment of micro-etching depth of 1.5 --- 2 microns, micro-etching before the pattern plating 0.3 --- 1 micron, the best conditions through the chemical Analysis and simple test Weighing method controls the thickness of micro-etching or etching rate; Under normal circumstances, the plate surface after micro-etching bright color, uniform pink, no reflections; if the color is uneven, or there is reflection of per-processing quality Hidden dangers; pay attention to strengthen the inspection; other micro-etching tank copper content, bath temperature, load, micro-enchant content are items to be noticed.
Some of the above can be said that in the actual circuit board production and PCBA assembly process, the more common causes of the surface blistering. Of course, there are many reasons that cause the foaming of the board, and foaming phenomenon may occur due to different reasons for the technical level of different manufacturers' equipment, so this needs specific analysis of specific situations.