Study On Preparation And Properties Of RFID Conductive Ink

With the rapid development of Internet of Things and RFID technology, the demand for RFID electronic label is growing and its application form extends with each passing day. As a key component of the electronic label, most of RFID electronic label antenna is prepared through traditional etching process. However, a large number of metal waste is produced in etching processing and may pollute the environment. Conductive ink printing method in RFID electronic tag preparation has the advantages of low cost, high efficiency, no pollution etc, which is the future development direction of RFID tag antenna manufacturing technology. The paper has chose screen printable RFID conductive ink as the object of study. A systematic study of RFID conductive ink was developed from three aspects: conductive phase silver powder preparation and application in conductive ink, the design of binder system in conductive ink and its performance, research on rheology of conductive ink.Different sheet sizes of flake silver powder were prepared by mechanically ball milling process. The effect of silver particle size on ball milling process and the properties of flake silver powder was studied. Silver flake diameter was increasing with milling time firstly. However, when the flaking process reached the limit, sheet size of flake silver powder decreased. The smaller sizes of silver particles, the shorter time sheet size reaching the limit and the more irregular flake silver powder with the same balling process. A steel-assisted polyol method has been proposed for high-concentration and large-scale preparation of screen printable 1D silver wires with low aspect ratios(10~20). Conductive properties, viscosity and solvent release property of conductive ink with different types of silver powder were investigated.A thermoset-thermoplastic resin blend was designed. Epoxy resin was used as the thermosetting resin and PVB(Polyvinyl butyral) was used as the thermoplastic resin. The curing process was 120℃in blast drying box for 30min according to the curing behavior of epoxy binder system and chosed solvents. The effect of silver content, binder resin components in conductive ink on volume resistivity, adhesion, printing and anti-bending performance of cured films were investigated. The higher silver content of conductive ink, the better conductive property and the bigger brittleness of cured film; The higher PVB content of Binder system, the better bending resistant performance and stronger adhesive force of cued membrane. In addition, conductive ink with higher PVP content had higher viscosity and more viscous components, so the pattern printed had the irregular edges and appeared many burrs.Shear-thinning characteristics, dynamic yield stress, thixotropy, thixotropic structure recovery rate and dynamic viscoelastic properties were measured using a rheometer. Rheological properties and anti-settling performance of conductive ink with different silver content, different silver types and thixotropic agent content were studied. Yield stress, zero shear viscosity and infinite shear viscosity of conductive ink obtained by curve fitting of viscosity measurable using Cross and Herschel-Bulkley rheological model were proved right and would play great important roles in conductive formulation design.