Hole metallization of FPC and the cleaning process of copper foil surface

              Hole metallization of FPC and the cleaning process of copper foil surface


     Fabrication process of Hole Metallization and Double-sided FPC

     The  hole metallization process of FPC is same as therigid printed board.

     In recent years, instead of chemical plating, direct electroplating technology has been used to form a carbon conductive layer. This technology has also been introduced into the hole metallization of flexible printed board.


     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 layer, must be flexible the printed circuit board is tightened in the fixture, and we should also work hard in the position and shape of the electrode.


    If the hole metallization is outsourced, it is necessary to avoid outsourcing to the factory without flexible PCB perforation experience. If there is no special plating line for flexible PCB, the pore quality can not be guaranteed.

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    Cleaning the surface of copper foil-FPC manufacturing process

     In order to improve the adhesion of the resist mask , it is necessary to clean the surface of the copper foil before the resist mask is applied , even if such a simple process requires special attention for the flexible printed board .


   There are chemical cleaning process and mechanical grinding process in general cleaning. For the manufacture of precision graphics, most of the occasions are to combine the two cleaning processes for surface treatment. The method of brush is used in mechanical grinding. Too hard brushing material can cause damage to copper foil, too soft and insufficient grinding. Generally using nylon brush, the length and hardness of the brush must be carefully studied. Use two brush rollers on top of the conveyor belt. The direction of rotation is opposite to the direction of belt transfer, but if the pressure of throwing brush roller is too high, the substrate will be elongated by great tension, which is one of the important reasons for the change of dimension.


   If the surface treatment of the copper foil is not clean , the adhesion to the resist mask is poor , thus reducing the qualification rate of the etching process . Recently , the surface cleaning process can be omitted in the case of a single - sided circuit due to the improvement in the quality of the copper foil plate . However , the surface cleaning is necessary in the case of a precision pattern of less than 100 . mu.m or less .