Sintering of inkjet printed copper nanoparticles for flexible electronics

Inkjet printed patterns using copper nanoparticles (NPs) were sintered at 250 °C under reducing atmosphere. The size of NPs covered by organic capping molecules was 5 nm on average. A crack-free Cu film was obtained after sintering. The grain size of the film reached 500 nm upon grain growth. However, only agglomeration of NPs was observed at the bottom of the film. The resistance was 0.88 Ω on average and the patterns were electrically tested by light-emitting diodes.