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  • How to solve the problem of coating too thick on plating hangers?
    Date :2017-3-17

    PCB electroplating on coating thickness when there will be a variety of adverse effects, which mainly include the following:


    1 plating parts will appear at the hook
    The contact part of the plating part and the hook is thickened, and the plating part is covered by the covering surface, thereby affecting the normal deposition of the layer.
    2 hooks easily broken
    Rack coating is too thick, will inevitably lead to uneven coating thickness, especially the contact point hook directly linked to workpiece coating is thin, and its surrounding coating will be very thick, at this point where the force will break, hangs the workpiece will be scattered, or bad quality accident.
    3 increase production costs
    With the rack coating thickened, the surface area will increase accordingly, heavy metals on the increase, with the rack (workpiece) with the increase of solution at the same time, the consumption of energy increase.
    4 plating liquid contamination between each other
    Rack coating thickness, the coating surface roughness to improve cleaning quality, reduce. Adsorption hanger surface is difficult to clean, which will cause the bath between contaminated.




    On the rack coating stripping, general plating according to the plating plating on the plating stripping method for the same. Too thick chromium layer on the rack is often thick chrome, back takes a long time, then you can use the characteristic of brittleness, tapping with a hammer hammer removing method, chromium layer will went off on their own, sometimes with wire clamp plate coating that will fall off on their own. Hanging galvanized, cadmium plating, tin plating, plating black nickel plating on coating should be used once a refund, in order to avoid the pollution of other types of plating bath in the pretreatment process.


    The nickel layer steel rack can be used the following method: removing nitrate (HNO3 1000mL/L), sodium chloride (NaCl), 30~50g/L temperature 40~60. The disadvantage of the process is that the nitrogen oxides are generated, and the work needs to be carried out under the condition of good air exhaust, and the water is prevented from being brought into the liquid to avoid corrosion. In the process of containing the sodium cyanide, sodium sulfate and sodium sulfate in the main formula of the nickel layer, can be carried out at room temperature, so as to avoid the rapid decomposition of sodium cyanide and ammonia solution.


    Hanging anodized aluminum used must be used once to carry back membrane treatment, otherwise can no longer conduction current. Stripping can be carried out in acidic solution, can also be carried out in alkaline solution, acid stripping liquid film to film back back to do, basically no corrosion occurs on the substrate, thereby prolonging the service life of hanger. But the process is troublesome, need high temperature liquid, and the stripping speed is relatively slow, in addition to the two kinds of film removing treatment can be used, also available file will contact with the site file, the file after the film is part can be used; (non contact with the workpiece parts allows a film). Some of this rack used film removing method can also greatly improve the service life of the hanger.


    PS: Retired precious metal rack containing precious metal solution to safekeeping, if necessary for recycling.



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