Low-temperature calcination of convenient micro-sized copper ink with surface activation and synchronous protection by in-situ chemisorbed cupric formate

The main problem of copper nanoparticle inks is the oxidation of copper nanoparticles because of the high reactivity. Therefore, less oxidable micro-sized copper particles become an ideal alternative copper source. However, micro-sized copper particles cannot sinter at low temperatures. In this study, with the combination of formic acid treatment and complexation with amine, the low-temperature calcination of micro-sized copper ink is achieved. Formic acid treatment can activate the surface of micro-sized copper particles, immediately followed by in situ chemisorbed cupric formate (CuF) on the surface to protect it from oxidation. 3-Dimethylamino-1,2-propanediol (DMAPD) can coordinate with the chemisorbed CuF on the surface and serve as a reducing agent during the calcination process. When the chemisorbed CuF-DMAPD decomposes to generate copper nanoparticles, the activated copper surface is exposed and serves as nucleation sites to form nano-channels. Finally a copper film with the resistivity of 19 +/- 2 mu omega cm was obtained after calcined at 180 degrees C for 10 min under N-2 atmosphere.