A facile and universally applicable additive strategy for fabrication of high-quality copper patterns based on a homogeneous Ag catalyst ink

Additive strategy has been regarded as a promising approach for fabricating electronic copper patterns, since it has predominance over traditional lithography technology (subtractive strategy) in process simplicity, material economizing, and environmental protection. At present, the key challenge for additive strategy is how to precisely fabricate high-quality copper patterns adhering tightly to substrates, by facile and universally applicable process. Here a novel additive copper patterning process is explored by adopting a homogeneous Ag-based catalyst ink. The catalyst ink can be facilely patterned and tightly attached on various substrates by different patterning techniques, without any pre-and post-treatment procedures. In the catalyst ink formula, epoxy matrix contributes high adhesiveness and fixes ink form, valen Schiff base acts as a medium anchoring Ag catalyst, ethanol serves as both reductant and diluent, and polyethylene glycol improves hydrophility. The copper coating, forming on the catalyst layer by further electroless copper deposition process, exhibits compact structure and high electrical conductivity comparable to bulk copper. Moreover, the copper coating can be partially inserted into substrate body by porous surface design for substrates, thus achieving strong adhesion and high flexibility. This research contributes to the progress of next-generation copper patterning techniques.