Polyimide (PI) film is an insulator and has been commonly used as a dielectric layer of a flexible printed circuit board (FPCB) due to its high thermal stability, good mechanical strength, and excellent chemical resistance. For FPCB fabrication, PI is a dielectric layer which means its surface has to be metallized. However, the copper line width and space is about 5/5 micrometer on FPCB, so FPCB with fine pitch has to be manufactured by semi-additive process (SAP). PI-SAP will not use copper foil anymore. Instead, PI will directly be metallized by electroless deposition and then copper electroplating to form the conducting lines. Because the copper line on the PI surface is very thin and micro-scaled, the peeling strength is a very critical target in the metallization. In this study, we used an overall wet process to directly metallize the PI film. Plating a barrier layer was performed on a PI film as seed and barrier layer followed by copper electroplating.

Polyimide (PI)、Flexible Printed Circuit Board (FPCB)、Electroless Copper Deposition、Metallization