Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Differentdefect on circuit board surface

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Differentdefect on circuit board surface | 10 July, 2020

From the poor bonding strength of the board, the surface quality problems of the board are divided into: 1. The cleanliness of the board surface; 2. The problem of micro graphite (or surface energy) on the surface. PCB circuit board proofing Youke board summary may cause board surface quality during production and processing is divided into: 1. The problem of substrate processing: Especially for some thin substrates (generally less than 0.8mm), it is not suitable to use a brushing machine to brush the board because the rigidity of the substrate is poor. In this way, the protective layer specially treated to prevent oxidation of the copper foil on the board surface during the production process of the substrate may not be effectively removed. Although this layer is thin and the brush plate is easier to remove, it is only difficult to apply chemical treatment, so it is important in production and processing Pay attention to control, so as not to cause the blistering problem of the board surface caused by the poor bonding force between the substrate copper foil and the chemical copper; this problem will also exist when the thin inner layer is blackened, and the blackening and browning will be poor, the color Uneven, partial black browning is not superior. 2. The phenomenon of poor surface treatment caused by oil stains or other liquids contaminated with dust caused by the surface of the board during machining (drilling, crushing, milling, etc.). 3. Bad Immersion Copper Brush Plate: The pressure of the grinding plate before the Immersion Copper is too high, causing the orifice deformation to brush out the copper foil fillet of the orifice or even the leakage of the substrate, so that it will be caused in the process of electroplated tin plating and soldering The blistering phenomenon of the orifice; unless the brush plate does not cause liquid leakage, but the excessively heavy brush plate will increase the displacement of the copper of the orifice, so that the copper foil is prone to excessive roughening during the micro-etching roughening process. There will also be certain quality hidden dangers; therefore, we must pay attention to strengthening the control of the brush plate process, and the brush plate process parameters can be adjusted to the best through the wear scar test and the water film test. 4. Water washing problem: Because the copper plating process is subject to a large amount of chemical treatment, various types of acid and alkali electrodeless organic solvents and other pharmaceutical solvents are dissolved, and the board surface is not cleaned, especially the copper plating adjustment degreaser, otherwise it will cause cross-contamination. At the same time, it will also cause partial treatment of the surface of the board or poor treatment effect, uneven defects, causing some problems in binding force; therefore, it is necessary to pay attention to strengthening the control of washing, mainly including the washing water flow, water quality, washing time, And the control of the dripping time of the board; especially when the temperature is reduced in winter, the washing effect will be greatly reduced, and more attention should be paid to the strong control of washing;

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