Abstract
This research proposed a sequential copper nanoparticle sintering process, which includes low pressure drying, near infrared sintering, and intensive pulsed light reduction. This process was designed for copper nanoparticle inks with lower solid contents and larger particle sizes, making the reduced copper thin film by inkjet printing or coating having the sane order resistivity as the bulk one. The result proved that the low pressure drying accumulated copper nanoparticles during solvent evaporation, resulting flat surfaces for continuous sintering. The near infrared sintering was efficient because of similar near infrared and copper absorption spectra, improving the copper delamination resulted from intensive pulsed light-only sintering. The low intensive pulsed light dose was used for copper-oxide reduction and avoided uniformity issue of stitching multiple areas. The final copper thin film resistivity reached 7.1×10-8 Ω-m, which equals to 24 % of the bulk conductivity.