Study On Preparation And Properties Of Silver Conductive Ink For Printed Electronics

With the need of the low cost and high efficiency in manufacturing, printed electronics technology has been rapidly developed and has a growing numbers of applications.Conductive ink is one of the priorities of the research.Traditional nanoparticle inks generally are composed of silver nanoparticles. In the process of synthesis and separation of nanoparticles, sintering and cleaning procedure, plenty of organic matters have to be used.On the one hand the use of organic matters is wasteful; on the other hand some of the toxic substances also cause environment pollution problem. And because of the property of nanoparticle is easy to sedimentation and coalescence, some restrictions may be concienced when chosing the proper printing equipment. It is also difficult to meet the requirements of linewidth of high desity circuit. Therefore, it is of great value to develop a non-nanoparitcles silver conductive ink that silver can deposite directly on the substrate by chemical reduction.In this thesis we used silver ammonia solution prepared from AgNO3 as the silver source, and Diethanolamine solution as the reducing agent.Mixed that two kinds of solutions, a clean and stable silver conductive ink was geted.The liquid phase chemical reaction and the procedure of silver crystal nucleation and growth mechanism was studied.The formation of conducive path using silver conductive ink and the conductive mechanism determinated by different theories was discussed. When heated the ink printed on the Substrate, diethanolamine was composed to formaldehyde which reacted with silver ammonia ions to form silver tracks.The variation of silver conductive ink in reaction precess and sintering process was discussed by UV-vis absorption spectroscopy, differential scanning calorimetry test(DSC), thermal gravimetric analysis test(TGA). Silver tracks were elemental silver with a face-centered cubic structure after sintering determined by X-ray diffraction(XRD).The silver conductive ink could improve the phenomenon that aqueous suspension deposed non-uniform explained by coffee ring effect. A more homogeneous silver particles deposition was obtained by microcope.The content of silver in the tracks and the affect condition was analysised by EDS test. The morphology of the sample and its influence was discussed, caused by reaction temperature, diethanolamine concentration, reaction time and concentration of silver nitrate. And the change of the morphology before and after sintering was also obtained. The resistivity of silver tracks was tested at different concentrations of the reactants, different reaction times and temperatures and different sintering temperature and times.The experiment explained that the preparation and application of silver conductive ink was simple and effective. The resistivity of printed tracks was 8.3×10-6?·cm found to be the best under the following conditions: The silver conductive ink was a mixed of silver ammonia solution(3.0 mol/L) and diethanolamine solution(3.0 mol/L). The ink printed on the substrate was heated at 95℃ for 6 hours and was sintered at 220℃ for 8 minutes.