Because the soft and hard bonded plate is composed of several different materials laminated together, due to the inconsistency of its thermal expansion coefficient, the hole wall and the line connection between layers are prone to fracture and tear phenomenon, improve the reliability of the soft and hard bonded plate hole metallization and the bonding force between the line lamination, is the key technology of the soft and hard bonded plate quality. The traditional process uses chemical potions wet process, the characteristics of the potions are not strong acid or strong alkaline, which will be adverse to polyimide resin, acrylic resin and so on. The dry treatment technology using plasma to clean, coarser and activate the material surface can not only obtain good reliability and binding force, but also overcome the defects of the traditional process and realize the green environmental protection process without emission.

The main material of FPC printed circuit board (soft board) is composed of polyimide resin. Due to the heat generated during drilling, it is easy to leave a large amount of resin glue residue in the hole, resulting in poor connection between the copper plating layer of the hole wall and the inner line, and even open circuit fracture phenomenon. Currently, resin swelling agent and potassium permanganate potion are commonly used in the industry to remove the glue residue in the hole. Potassium permanganate has great destructive effect on polyimide resin properties. The low temperature plasma treatment can effectively remove the residual glue of the hole wall, and achieve the effect of cleaning, activation and uniform etching, which is conducive to the connection between the inner line and the copper plating layer of the hole wall, and enhance the binding force. Plasma treatment before chemical plating and electric plating can effectively remove the dirt on the surface of the pad and eliminate leakage plating. Before SMT, plasma treatment can effectively remove the dirt on the pad surface and eliminate virtual welding.