What are the Manufacturing Technologies for Flexible Copper Clad Laminates

Whatever it is a 3 layer flexible copper clad laminate or 2 layer flexible copper clad laminate, there are three main manufacturing technologies. Each FCCL manufacturer will adopt different technologies according to its own characteristics. Do you know what manufacturing technologies are used in flexible copper clad laminates?

1. Coating Method

The coating method is a copper foil coated with adhesive, uniformly coated the prepolymer of liquid polyimide resin, such as the copper foil of the 2 layer flexible copper clad laminate without an adhesive layer, and then pass it through the adhesive layer, and then through heating and drying, the coating resin is imidized to form a polyimide resin film. For 2 layer flexible copper clad laminates, generally in order to improve the higher adhesion between the resin layer and the copper foil, some technologies first coat a layer of high-adhesion polyimide resin on the surface of the copper foil. Then, a polyimide resin layer with high dimensional stability is coated on it. Finally, imidization is performed to form a film.

The advantages of coating method is that it can obtain higher bonding strength between the resin and the copper foil. In addition, it is easy to produce FCCL with a thin base material. There is a high degree of freedom in the choice of metal foils.

2. Lamination Method

After the foils are laminated together, they are subjected to high-temperature and high-pressure lamination forming processes. Since the melting point of hot-melt polyimide resin is above 300°C, its lamination process needs to be carried out at a temperature close to 350°C and under vacuum pressing conditions. It is difficult to form roll-shaped products of the flexible copper-clad board by laminating method.

The lamination method of 3 layer flexible copper clad laminate is similar to this. However, some manufacturers can perform continuous heating.

3. Plating/Chemical Plating Method

On the polyimide film, plating (vacuum plating, etc.)/chemical plating is used to form a copper conductor layer. If chemical plating is used, a thinner conductor layer can be produced.  In the technology of forming a conductive layer by electroplating, a thin "base layer" is often electroplated on the film. It plays the role of stiffener the bonding between the copper layer and the film. The "base layer" is mostly composed of chromium or nickel metal. Due to the presence of chromium metal in the base material of FPC, residues are usually produced during etching of the copper layer in PCB manufacturing.

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