Research On The Preparation And Printability Of Nickel Conductive Ink

Due to its low cost,abundant reserves,and excellent physical and chemical properties,metallic nickel was gradually replacing the dominant position of precious metals in electronic components.Nano-sized nickel powder is prone to agglomeration in ink application due to its huge surface effect and volume effect and its dispersion directly affects the conductivity and printability of nickel conductive ink.Thus,it was necessary to study the factors affecting the dispersion performance of nickel conductive ink.For the final application in multilayer ceramic capacitors(MLCC),using nickel powder with nano-sized as raw material,the dispersant,dispersion time,pH value and solid content of nickel powder were changed in the solvent terpineol to carry out the dispersion experiment by mechanical high-speed stirring.Based on the Stokes sedimentation formula and laser confocal microscope,the dispersion performance of nickel powder was characterized,analyzed and compared.At the same time,the nickel conductive ink obtained under the optimal dispersion conditions was gravure proofed on18 flexible substrates in order to study the printability of nickel conductive ink.A series of characterizations were performed on the printed samples to study and find the substrate suitable for nickel conductive ink printing.The study found:(1)When using PVP,T-154,7605 dispersant,the best dispersion time for nickel powder was 5 hours,and the best dispersion time for dispersant PEG,Citric Acid and no dispersant was 6 hours.Among them,PVP exhibits the best dispersibility of nickel powder due to it own anchor group and solvation chain at the same time,and the mass ratio of PVP to nickel powder should be controlled between 1%to 3%.(2)The pH value of the dispersion system and the solid content of the nickel powder were studied when using PVP as the dispersant of nickel conductive ink.When the pH value was 6,the Ni-OH groups with better lipophilicity was formed on the surface of the nickel powder particles.However,when the acidity was stronger,the poor lipophilic Ni-OH²⁺group was formed and the lower lipophilic Ni-O-group was produced under the alkaline condition.So the best dispersion performance of nickel powder was showed when the pH value was 6.At the same time,regardless of the solid content of the nickel powder,the optimal state of monodispersion of nickel powder in the dispersion system was reached when the pH was 6,and when the pH value was 2,4,8,the dispersion effect of nickel powder at a solid content of 50%was better than other solid content.(3)By comparing the line width,printing area coverage,color density and ink layer thickness of the printed samples,7 flexible substrates that were more suitable for nickel conductive ink were obtained.They were:Ceramic,Porcelain flake,PP high-gloss paper,PP matte paper,Crystal photo paper,PET film and Matting eco-solvent paper.Due to the excellent lipophilicity of the substrate surface or the adsorption and penetration effect of the microporous structure,the good printability of these substrates was appeared.