The hole metallization process of flexible PCB is basically the same as that of rigid PCB.
In recent years, instead of electroless plating, direct electroplating technology is adopted to form carbon conductive layer.Hole metallization of flexible PCB also introduced this technique.
Due to its softness, flexible printing plate needs special fixed jig. Jig can not only fix the flexible printing plate, but also must be stable in the plating solution, otherwise the thickness of copper plating is not uniform. This is also an important reason for line breakage and bridge in the etching process.To achieve a uniform copper plating, the flexible printing plate must be taut within the clamp and work on the position and shape of the electrode.
For the processing of hole metallization, we should try our best to avoid outsourcing to the factory without the experience of punching flexible PCB.
Cleaning of copper foil surface -FPC manufacturing process
In order to improve the adhesion of the mask, the surface of the copper foil should be cleaned before the mask is applied.
General cleaning has chemical cleaning process and mechanical grinding process, for the production of precision graphics, most of the occasion is to combine the two cleaning process for surface treatment.The mechanical grinding method USES the brush, the brush material is too hard will cause damage to the copper foil, too soft will be grinding insufficient.Usually nylon brush, the length and hardness of the brush must be carefully studied.
Two brush rollers are used to put on the conveyor belt. The rotation direction is opposite to that of the belt. However, if the roller pressure is too high, the base material will be stretched due to great tension, which is one of the important reasons for the size change.
If the surface treatment of the copper foil is not clean, the adhesion to the resist mask will be poor, which will reduce the qualification rate of the etching process.As the quality of the copper foil has improved recently, the surface cleaning process can be omitted in the case of single-sided circuits.However, surface cleaning is an essential process for the precision graphics below 100.