Fabrication of flexible copper patterns by electroless plating with copper nanoparticles as seeds

Flexible conductive copper patterns with low electric resistance, good adhesion, and high stability were successfully prepared on heat-sensitive polyethylene terephthalate (PET) substrate by combining the inkjet print with copper nanoparticles (Cu NPs) conductive ink and electroless plating (ELP) copper at room temperature. The Cu NPs served as the catalysts to promote copper ions electroless deposition on PET surface. Dimethylaminoborane (DMAB) was used as the reductant to place poisonous formaldehyde in the electroless plating process. The Cu patterns had a strong adhesion with PET substrate modified by 3-Mercaptopropyltriethoxysilane (MPTES) and would not fall even after 4000 cycles bending test. The electric resistivity of patterns could be as low as 5.43 μΩ·cm, which is about three times that of bulk copper. The minimum sheet resistance of the patterns was 54 mΩ/sq and had little change in the atmosphere for five months, that showed the patterns had an excellent anti-oxidation performance.