Preparation Of Copper Based Particle-free Conductive Ink And Its Film Formation Investigation

Printed electronics is an emerging technology of manufacturingmicro-electronics. It makes the organic confluence of printing technology andelectronic technology, thus printing various electronic products on various substrates.The core of printed electronics is transferring functional ink materials onto substrates,suffering some post-treatments, making the ink materials own the necessary electricalproperties. The research of conductive inks guarantees the wide application of printedelectronics greatly. Recently, conductive inks based on copper have received more andmore attention because of their favorable conductivity and low cost. Among these,particle-free copper inks contain no nanosized copper particles which avoid theproblem of oxidization, and also have high stability.Thermal behaviors of organic-copper salts and their amine complexes wereinvestigated in this study. Due to the easily oxidization, complex decompositionproperties and high decomposition temperatures, it’s difficult to obtain pure coppersimply based on the decompositions of copper salts and their amine complexes.In this study, copper conductive ink with low post-treatments temperatures andhigh stability was prepared, taking copper (II) acetate monohydrate as conductivemetal precursor, organic amines as complexing agent, formic acid as reduction agentand alcohols as media adjusting the surface attention and viscosity. The influence ofalcohols, formic acid and amines on the thermal behaviors of conductive inks wasinvestigated. The results showed that methanol which acted as the main adjustingmedia of physical parameters showed little influence on the thermal behaviors of inks;there was an optimum amount of formic acid in the ink system, and more or less thanthis amount would make the decomposition temperature higher; the influence ofamine on the thermal behaviors was complex. Many factors should be considered, notonly the carbon chain structure, substituent group number. On the basis of theinvestigations above, taking the system of cyclohexane and N,N-dimethylethanolamine as examples, the film-forming capability of the inks was explored. Theresults showed that the ink of cyclohexane system could obtained a low resistivity of5.3μΩ·cm after sintering at250℃. And XRD showed the film contain pure copperparticles. The decomposition temperatures of copper-amine complexes were decreased greatly after the join of formic acid.