Flexible circuit board plating
(1) FPC electroplating pre-treatment Flexible printed board FPC may have adhesive or ink contamination on the surface of exposed copper conductors after the coating process, but also oxidation and discoloration due to high temperature process. A tightly adherent, closely plated layer must remove conductor surface contamination and oxide layers and clean the conductor surface.
However, these contaminants and copper conductors are very strong, and can not be completely removed with a weak cleaning agent, so most often use a certain intensity of alkaline abrasives and throwing brush and used for processing, most of the overlay adhesive are ring Oxygen resins and poor alkali resistance, which will lead to a drop in bond strength, although not obviously visible, but in the FPC plating process, the plating solution may infiltrate from the edge of the cover layer, in severe cases, the cover will be stripped . In the final welding, the phenomenon of solder drilling under 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, and must give full attention to the processing conditions.
(2) FPC electroplating thickness When electroplating, the electroplating metal deposition rate has a direct relationship with the electric field strength, and the electric field strength changes with the shape of the circuit pattern and the positional relationship of the electrodes. According to the coating online knowledge, the line width of the general wire is greater. Finer, the sharper the terminal at the terminal, the closer the distance to the electrode is, the stronger the electric field strength is, and the thicker the plating at this position is.
In applications related to flexible printed boards, in the case where many wire widths are extremely different in the same wire, it is more likely to cause uneven plating thickness. In order to prevent this from happening, a shunt cathode pattern can be attached around the wire. It absorbs uneven current distributed in the plating pattern and maximizes the uniform thickness of the plating on all parts. Therefore, we must work hard on the structure of the electrode. A compromise solution is proposed here, strict standards are applied to areas with high coating thickness uniformity, and relatively relaxed standards for other parts, such as the lead-tin soldering of fusion welding and the gold plating layer of the metal wire (welded). High, but for the general use of anti-corrosion plating tin, its plating thickness requirements are relatively relaxed.
(3) FPC electroplating stains, dirt plating state just after electroplating, especially the appearance is not a problem, but soon some of the surface appears stains, dirt, discoloration and other phenomena, especially when the factory inspection did not find What is different, but when the user receives a check, it is found that there is a problem with the appearance. This is due to insufficient drifting, residual plating on the surface of the coating, and chemical reactions that occur slowly over a period of time.
In particular, a flexible printed board, which is soft and not very smooth, is susceptible to accumulation of various solutions in the recesses, and then reacts and discolors at this site. In order to prevent this from happening, not only sufficient drifting is required, but also It should also be fully dried, and high temperature thermal aging test can be used to confirm whether sufficient drifting has occurred.
Flexible circuit board electroless plating
When the line conductor to be plated is isolated and cannot be used as an electrode, electroless plating can only be performed. The electroless plating bath used has a strong chemical effect. The electroless gold plating process is a typical example. Electroless gold plating is an alkaline aqueous solution with a very high pH. According to coating online, when using this plating process, it is very easy for the plating solution to drill under the mantle layer, especially if the quality of lamination film lamination process is not strict and the bonding strength is low, this problem is more likely to occur.
The electroless plating of the displacement reaction is more likely to cause the phenomenon that the plating solution penetrates under the covering layer due to the characteristics of the plating solution, and it is difficult to obtain the ideal electroplating conditions by electroplating in this process.
Flexible circuit board hot air leveling
This process, developed for the application of lead and tin on PCBs with rigid printed boards, is also applied to flexible printed boards FPC due to its simplicity. Hot air leveling is to dip the board directly into the molten lead-tin bath and the excess solder is blown away with hot air. This condition is very severe for a flexible printed circuit board (FPC). If no measures are taken to prevent the FPC from being immersed in the solder, the flexible printed circuit board (FPC) must be sandwiched between the screens made of titanium steel. Then, dip into the molten solder. Of course, the surface of the FPC printed on the flexible printed board must be cleaned and coated with flux.
Due to the harsh process conditions of hot air leveling, the phenomenon that the solder is drilled from the end of the covering layer to the underlaying layer is likely to occur. Particularly, when the bonding strength between the covering layer and the copper foil surface is low, this phenomenon is more likely to occur frequently. Because the polyimide film is easy to absorb moisture, when the hot air leveling process is used, the moisture-absorbing moisture may cause foaming or even peeling of the cover layer due to the rapid evaporation of heat, so the coating line is recommended to be performed before the FPC hot air leveling is performed. Drying and moisture management.
This kind of power supply is also called industrial switching mode power supplies (SMPS) – It is a type of AC to DC, it obtains energy from the power grid, a DC high voltage is obtained through high voltage rectifier filtering, DC/DC Converter obtains one or more stable DC voltage at the output end, and the power can be produced from several watts to several kilowatts for different occasions. The specifications of switching power supply are various, the standard are 5V 12V 24V LED Power Supply, including single output, dual output and triple output power supply. They are widely used for LED strip, led module, led lamp and CCTV camera.
Power Supply,Switching Power Supply,Switch Mode Power Supply,12V DC Power Supply
Shenzhen Yidashun Technology Co., Ltd. , https://www.ydsadapter.com