Knowledge of FPC surface plating on flexible circuit board

- Sep 15, 2018-

1. Flexible circuit board FPC plating

(1) flexible PCB FPC FPC electroplating before processing after cladding coating exposed surface of the copper conductor may have adhesive or ink pollution, also there will be generated due to the high temperature process of oxidation, discoloration, to obtain good tight adhesion coating must remove pollution and oxide layer on the surface of the conductor, the conductor surface clean.But some of these pollution is combined with copper conductor is very strong, with weak detergent cannot completely remove, so that most often used with a certain intensity of alkaline abrasives and brush and used for processing, most layer adhesives is a kind of epoxy resin and alkali resistant performance is poor, so as to cause a decline in bonding strength, though not visible, but in FPC electroplating process, plating solution is likely from the edge of the cover, serious when overburden stripping.During the final soldering, the solder drillers appear under the overburden.It can be said that the pretreatment cleaning process will have a significant impact on the basic characteristics of flexible printing plate F{C. 

(2) the thickness of the FPC electroplating electroplating, plating metal deposition rate is directly related to the intensity of electric field and electric field intensity and with the shape of the line graph, the position relationship between electrodes, the general wire line width of the thinner, terminal parts of the terminal is pointed, the greater the closer the distance of the electric field intensity and electrode, the parts of the coating is thick.In with the flexible PCB related use, in the same line width difference many conductors in great conditions exist it's easier to produce coating thickness is not uniform, in order to prevent the happening of this kind of situation, can be in line attached diversion around the cathode graphics, absorb graphics on uneven current distribution in electroplating, coating thickness on the maximum guarantee all parts evenly.So you have to work on the structure of the electrode.Proposed a compromise here, for the part of the high standard strict coating thickness uniformity, for the other parts of the standard relatively relaxed, for example, the fusion welding lead, tin plating, metal wire by (welding) of gold plated layer standard is higher, and for general corrosion of lead, tin plating, the plating thickness required relatively relaxed. 

(3) FPC electroplating stains and dirt have just been electroplated on the coating state, especially there is no problem with the appearance. However, some surface stains, dirt, discoloration and other phenomena appear soon after. In particular, no abnormal appearance is found in the factory inspection.This is due to insufficient drift, coating surface on the residual liquid, after a period of slow chemical reaction caused.In particular, flexible printing plate, due to soft and not very smooth, its concave is easy to have various solutions "accumulated?In order to prevent the occurrence of this situation, not only sufficient drift, but also sufficient dry treatment should be carried out.The high temperature thermal aging test can confirm whether the drift is sufficient.