FPC plating pretreatment
The surface of the copper conductor exposed by the flexible printed board FPC after the coating process may be contaminated by adhesive or ink, and there may be oxidation and discoloration caused by the high temperature process. In order to obtain a tight adhesion with good adhesion, it is necessary to Contamination of the conductor surface and removal of the oxide layer clean the conductor surface. However, some of these pollutions are very strong in combination with copper conductors, and they cannot be completely removed with weak cleaning agents. Therefore, most of them are often treated with a certain amount of alkaline abrasive and brushing. The covering adhesives are mostly rings. Oxygen resin and poor alkali resistance, which will lead to a decrease in bonding strength. Although it is not obvious, in the FPC plating process, the plating solution may infiltrate from the edge of the coating layer, and in severe cases, the coating layer may be peeled off. . In the final welding, the phenomenon of soldering the drill to the underside of the cover layer occurs. It can be said that the pre-treatment cleaning process will have a significant impact on the basic characteristics of the flexible printed board FPC, and the processing conditions must be given full attention.
Flexible circuit board FPC electroless plating
When the line conductor to be plated is isolated and cannot be used as an electrode, only electroless plating can be performed. Generally, the plating solution used for electroless plating has a strong chemical action, and the electroless gold plating process is a typical example. The electroless gold plating solution is an alkaline aqueous solution having a very high pH. When such an electroplating process is used, it is easy to occur under the coating of the plating liquid, especially if the quality of the lamination process is not strict and the bonding strength is low, which is more likely to occur.
The electroless plating of the displacement reaction is more likely to occur under the coating layer due to the characteristics of the plating solution, and it is difficult to obtain ideal plating conditions by electroplating using this process.
Flexible circuit board FPC hot air leveling
The hot air plain is a technology developed for the coating of lead-tin on rigid printed circuit boards. Because of this technology, it is also applied to flexible printed board FPC. The hot air leveling is to directly immerse the board in the molten lead-slot, and the excess solder is blown off by hot air. This condition is very demanding for the flexible printed board FPC. If the flexible printed board FPC cannot be immersed in the solder without any measures, the flexible printed board FPC must be clamped to the middle of the screen made of titanium steel. Then, it is immersed in the molten solder. Of course, the surface of the flexible printed board FPC is also cleaned and coated with flux.