A novel electrochemical deposition of copper conductor on flexible printed circuit boards

This study employs a screen-printed aluminum paste to form electrode patterns on a substrate. Subsequently, a galvanic displacement reaction is utilized to replace the surface of the printed aluminum electrode with a copper seed layer. Finally, copper electroplating is performed to deposit copper onto the seed layer. This innovative additive aluminum-displacement-plus-electroplating process utilizes upward electroplating from the displacement-formed copper seed layer to enhance the electrical properties and smoothness of the copper conductor, while the downward electroplating strengthens the mechanical properties of the copper conductors.To ensure the complete conversion of the printed aluminum electrodes into copper electrodes, crystalline copper sulfate powder is incorporated into the aluminum paste. After 20 min of displacement followed by 30 min of electroplating, the internal aluminum is fully converted into copper, producing a copper layer approximately 100 μm thick. The resulting copper exhibits a resistivity of 2 × 10−8 Ω·m.Compared with conventional subtractive copper foil conductor processes, this method achieves comparable mechanical, chemical, and electrical properties. Furthermore, the simplified process reduces material waste and supports the pursuit of net-zero carbon emissions.