Additive Fine-Line Circuit Process through Catalyst Induced Copper Electroless Plating

To response the demand for fine line in electronic products, additive manufacturing process integrated printing techniques and deposited methods to reach fine line circuit, with the merits of reduced material wastage, low fabrication costs, and mass production advantage capability. Recently, we have developed additive process in fabricating circuit on flexible substrate through catalyst induced copper electroless deposition (ELD) method. The additive processes that integrated printing, activation, and metallization were applied to produce fine-line circuit with 5 μm line width. The sample with ultraviolet (UV) activation shows better conductive property in comparison with the sample without activation after electroless deposited process. Accordingly, the results indicated that the reaction of catalyst induced electroless copper plating strongly depends on UV activation. The fine-line circuit exhibits a narrow line width circuit (around 5 μm), lower resistance (6.2 μΩ·cm), and mass production with low pollution in comparison with lithographic processes (with photoresist and acid pollution) with a high throughput system (R2R system) for the applications of double side flexible printed circuit board (FPCB).