FPC hole metallization and copper foil surface cleaning process

* Fabrication technology of double sided FPC

The hole metallization of flexible printed circuit board is basically the same as that of rigid printed circuit board. In recent years, there has been a direct plating process, which is replaced by electroless plating and the formation of carbon conductive layer technology. This technique is also introduced in the fabrication of flexible printed boards.

Flexible printed circuit board needs a special fixture because of its soft, , 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 circuit board must be tightened in the fixture, and the position and shape of the electrode should be used.

* FPC cleaning process for copper foil surface

In order to improve the adhesion of the resist mask, it is necessary to clean the surface of the copper foil before coating the resist mask.

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 the method of throwing brush, polishing material will cause damage to the copper foil, too soft and will not be fully grinding. Nylon brush is generally, the length and hardness of the brush must be carefully studied.

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 surface treatment of copper foil is not clean, then the adhesion with the resist mask is poor, so it will reduce the pass rate of the etching process. Recently, due to the improvement of the quality of the copper plate, the surface cleaning process can be omitted in the case of a single circuit. But 1OO m below the precision graphics, surface cleaning is an essential process.