Surface treatment process in FPC PCB production process

- May 22, 2017-

In the increasing development of the electronics industry today, as the electronic products to the light, thin, short trend, improve the welding technology development of high performance and multifunctional and electronic device, flexible circuit board (FPC) as well as the circuit board for electronic interconnection has been in the past two years in China PCB industry to develop rapidly because of the electronic products, light, thin, short, soft PCB is applied to more and more wide, soft PCB and other type of printed circuit board, a lot of wiring in the narrow space, need repeated bending parts because of the use of special materials, so compared to other cable bending life has longer.

Because of the characteristics of lightweight, soft plate surface treatment in the process of selection of equipment and processing method of the special requirements, soft board production, cleaning the surface of a link is very important, because it requires not only the surface is in good condition, and the size stability of plate is also strictly requirements, the size stability depends on the size change in laminated copper foil layer rate, but also has very big effect in the production process and mechanical grinding, grinding brush roller running direction and transfer board in the opposite direction, is to ensure that the grinding effect is uniform, but the soft base is thin and soft, the pressure is too large when the substrate polishing will be under great tension and extended or broken, which is one of the important causes of size change, avoid scratches, tear and substrate pallets should be in the grinding process, if the device is not specialized in soft board production conditions, construction The pallet is adopted to avoid the deformation of the material board, or even the scrap due to the large distance between the driving wheel of the machine, the flushing of the high-pressure water and the drying of the hot air.

According to the production process of soft board requirements and grinding wheel, the soft PCB production process using chemical cleaning method and nylon brush roll is acicular pattern transfer, metallization and paste ideal film surface treatment process, not only to remove the copper oxide layer can do surface has good roughness.

In the electroless gold surface process before processing, can choose low cutting force non woven roller, because of its fine grinding effect, can ensure the removal of surface residue, butt welding disc fine grinding processing, this is the effect of surface treatment of nylon brush needle is not up to, because of its soft board general pads are smaller and less common needle nylon brush can not fully grinding to the pad, and the grinding strip will leave scratches, influence of welding and surface appearance.

Soft board for surface cleaning and grinding processing before metallization, in order to improve the binding force of the metallization layer and substrate, and the metallization patterns after imaging on copper surface effectively, to enhance the adhesion strength of copper foil and the resist layer is also very important, FPC hole metallization the front surface is not clean, the metallization coating may be layered and bubble image to clean the copper surface roughening is not enough, a combination of strength and corrosion resistance of the layer is not enough, the production of fine line patterns behind the electroplating process occurring leakage short-circuit plating, defects caused by plate scrap.

The chemical cleaning method is to remove the organic debris surface and organic pollutants by chemical agents, then the surface roughening treatment with micro etching solution, the copper surface treatment has good smoothness, and does not have any mechanical scratches and residual abrasive particles, so it is the fine line printing clean rough surface treatment method comparison the ideal processing board, but this method in removing copper foil surface is not easy to complete leveling of copper particles and the material is easy to oxidation, roughness of no mechanical polishing effect is good, suitable for mulching film paste treatment process before coating.

Flexible printed circuit board as the rapid growth of the industry, many materials and equipment still need to continuously explore, mass production needs on the field of technology and equipment, materials continuously complete, this paper extracted from a part of discussion on the factors influencing the quality of soft board, only to master the essentials of each link, in order to production a performance more reliable, more beautiful appearance of the product, China's growing soft PCB industry.

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