Hole metallization double faced FPC manufacturing process
The hole metallization of flexible printed boards is basically the same as that of rigid printed boards.
In recent years, the electroless plating process has been replaced by electroless plating. The technique of hole metallization for flexible printed boards also introduces this technique.
Flexible printed circuit board because of its soft, needs a special fixture, the fixture can not only put the flexible printed board is fixed, but also must be stable in the bath, or copper plating thickness is not uniform, which is an important cause of breakage and bridging in the etching procedure. In order to obtain a uniform copper plating layer, the flexible printed board must be tightened in the fixture, and the position and shape of the electrode must be worked hard.
Hole metal outsourcing processing, as far as possible to avoid outsourcing to no flexible printed circuit board hole experience factory, if there is no flexible printed circuit board special electroplating line, the quality of the hole is not guaranteed.
Cleaning process of copper foil surface by -FPC
To improve the adhesion of resist, it is necessary to clean the copper foil surface before coating the resist, even if such simple procedures require special attention to flexible printed boards.
General cleaning chemical cleaning process and mechanical grinding process for manufacturing precision graphic, is the two most occasions clean technology combined with surface treatment. Mechanical polishing using throwing brush method, throwing brush material is perfect, it will damage copper foil, too soft and will not fully grind. In general, a nylon brush must be carefully studied for the length and hardness of the brush.
Using two polishing brush roller, on top of the conveyor belt, and belt conveying direction of rotation in the opposite direction, but if the polishing brush roller pressure is too large, the substrate will be greatly elongated and tension, which is one of the important causes of size change.
If the copper foil surface is not clean, then the adhesion to the resist film is poor, which will reduce the rate of etching process. Recently, due to the improvement of the quality of copper foil panels, the surface cleaning process can also be omitted in the case of single-sided circuits. Surface cleaning is an essential step, however, for precise shapes below 1OO M.