Papers by Keyword: Surface Resistance

Abstract: This paper describes the characterization of conductive PDMS (CPDMS) composites. Composite have been achieved by filling the PDMS with CarbonBlack (CB). Two different methods were used to prepare the CPDMS composites: (A) direct mixing of CB with PDMS (CB-PDMS); (B) dissolving of CB in methanol before mixing with PDMS (CB-Methanol-PDMS). At a certain critical CB concentration, called percolation threshold, the membranes get conductive. Membranes of CPDMS (thickness ≈ 100µm) have been fabricated. CPDMS membranes of method (B) show a smoother surface profile as membranes of method (A). By means of a two–point resistivity measurement, the electrical resistance of CPDMS membranes was measured. With an increase of the CB concentration, the resistance decreases. Membranes of method (B) show a low percolation threshold and a low surface resistivity. Effects of pressure and temperature on the membrane resistance were investigated, too. Around the percolation threshold, the resistance shows the highest sensitivity on pressure and temperature variations. The Young’s modulus of CPDMS membranes exponentially increase with an increase of the CB concentration.

Abstract: Now insulation films are often prepared by smooth rubberroll on the surface of non-oriented silicon steel sheet. Though the surface resistance is enough high to ensure the quality, it will dramatically decrease after stress relief annealing. In order to understand the related mechanism, the film’s microstructure was characterized by SEM. The results show that the main composition of semi-inorganic coating is Cr, Mg C and O, in which C come from the organic polymer. According to the composition, the insulation film can be divided into two parts, the outer one is organic polymer and the inner one is chromate. The main reason for the unstable surface resistance is that the coating in the thickness direction is not uniformity.

Abstract: Printed electronic industry develops fast and has great potential. In order to prepare water-based nano-silver gravure conductive ink used for printed electronics, liquid chemical reduction method is used. Ag⁺ (5.89M) at high concentration acting as the precursor is reduced by hydrazine hydrate with PVP as the protecting agent. For one time of reaction, silver content of 9.25% is obtained. After washing and centrifuging the silver colloids for three times to purity, some amount of deionized water, resin and additives are added to the silver paste to fabricated water-based nano-silver conductive ink for gravure. Then, samples obtained by coating or proofing are dried and surface resistance and adhesion are measured. The results indicated that the silver particles prepared have size of about 50~100nm and most of the particles are spherical with small amount nanoplates. The nano-silver gravure conductive ink has 52.63% silver content and 3.58% PVP. Surface resistance of samples coated after sintering at 120°C for 30s can reach 129.5mΩ/sq and the resistivity is 1.49×10^-4Ω.cm. The ink layer surface has no drop after 3M method which indicating good adhesion. The ink is suitable for gravure and can be used in printed electronics.

Abstract: Graphene has unique structure and excellent performance , It has good optical, thermal, mechanical properties and electrical conductivity. In this article , based on elaborating the structure , characteristic and preparation methods of the graphene , the modification of graphene in polymer composite was discussed and the development and research direction of the graphene/polymer composite were proposed. The conductivity of poly (3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonate) (PSS) blended with different ratios of graphene/PVDF (polyvinylidiene fluoride) solution was measured. After dryness, we found that an addition of graphene/PVDF solution lowered the resistance by three or four orders of magnitude when the concentration are 25wt% and 50wt% , among them the Gb50 has the best surface conductivity, the magnitude is about 1.43 S/cm, and then we found that the second onset degradation temperature of PEDOT/PSS membrane blended with graphene/PVDF was 75°C higher than that of without blended with graphene/PVDF. All kind of dispersion has been studied using a four-point probe conductive meter, X-ray diffractometry (XRD), fourier transform infrared (FTIR), thermogravimetric analysis(TGA) and scanning electrical microscopy (SEM) in order to discuss the surface resistance, the crystallinity, the chemical structure , the thermal properties and morphology of the PEDOT/PSS-graphene/PVDF film. Conductive PEDOT/PSS-graphene/PVDF membrane has good electrical properties and thermal stability , which can be used for the electrolyte of lithium battery.

Abstract: The article prepares the jet ink with nano-silver synthesized by the lab and then adjusts the parameters of the silver colloid to fabricate nano-silver conductive ink suitable for ink-jet. Then patterns are obtained on the photo paper through EPSON ME 70 jet printing, and treated by three post-processing methods include laser sintering, heating, and solution soaking, which measured by four- point probe measurement and observed by SEM. It shows that after treatment the surface resistance of the patterns all decrease obviously. Patterns heated at 120°C for 10min, the resistance is 815mΩ/□, while the surface changes of silver layers can be observed obviously from SEM images. But the surface of the photo paper is destroyed with some bubbles on the coating surface. After 10min of laser sintering, the resistance of the silver layer reaches 890mΩ/□ from infinity. And when immersed in the NaCl solution for 5min, the patterns’ surface resistance decrease to 2.7Ω/□.

Abstract: This paper investigates the physical properties of conductive paste which is used for print engineering. The conductivity of poly (3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonate) (PSS) containing various organic solvents was measured. The different dielectric constant solvents are isopropanol, N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, dimethyl sulfoxide with different concentration. After drying, they were prepared many kinds of films. It was found that an addition of organic solvent lowered the resistance by two or three orders of magnitude when the concentration is 25wt% , among them the larger dielectric constant solvent has the best surface conductivity, the magnitude is about 7.03×10^－1 S/cm, and then we blend every two solvents by 25wt% concentration, prepared six blend films. Among them has the best effect, the magnitude is about 1.94×10^-1S/cm. All kind of PEDOT/PSS films have been studied using four point probe conductive meter, X-ray diffractometry (XRD), fourier transform infrared (FTIR), thermogravimetric analysis(TGA) in order to discuss the surface conductivity, the crystallinity, the chemical structure and the thermal properties of the PEDOT/PSS film. Conducting PEDOT/PSS-IPA/DMSO solution mix with polymethyl-methacrylate (PMMA) resin to coat hydrophobic fabrics, which can be used for the dissipation of electrostatic charge.

Abstract: The application of interference microscopy (IFM) and infrared microscopy (IRM) to monitor the evolution of the concentration of guest molecules in nanoporous host materials opens a new field of diffusion research in condensed matter. It combines the methodical virtues of the profiling methods of solid-state diffusion studies with the benefit of the mobility enhancement in fluids. We are going to illustrate the rich options of diffusion studies provided by this novel experimental approach.

Abstract: Organoclay has a low electrical conductivity and a proper dielectric constant which makes it to be used as a gate insulator. In a dry form, the organoclay exists in aggregates of montmorillonite platelets and very little surface area of the montmorillonite is exposed. For uniform dispersion of the clay aggregated, PA-66 and organically modified Na-montmorillonite (OMMT) were melting blended by using an internal mixer. The crystalline change and effects of intercalation were investigated with X-ray diffraction. Results of thermal properties, micro-structure, surface resistance and crystallization behavior indicated that OMMT had obviously effects on PA-66. DSC results showed that the existent of OMMT had effect on PA-66/OMMT nanocomposites and OMMT content had important effects on the scatter of OMMT in PA-66 matrix.

Abstract: To prepare the nano-scale silver carboxylate emulsions and investigate their applications in the preparation of nano-scale silver films, the silver citrate emulsion was synthesized through the reaction of silver nitrate with sodium citrate in the presence of polyvinylpyrrolidone (PVP) as a surface modification agent in water. The emulsion was coated onto the surface of the PET substrate to form a thin latex layer of silver citrate. And this was followed by drying at about 100 °C. Then, the silver citrate thin film was deoxidized by aqueous ascorbic acid. Finally, a translucent silver thin film was formed on the surface of the PET substrate. Properties of the silver citrate emulsion and the silver film on the PET were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), laser particle size analysis, scanning electron microscopy (SEM), thermogravimetry(TG) ,UV-visible absorption spectroscopy, atomic force microscopy(AFM) and digital multimeter analysis. It was found that the silver citrate particle surface-modified by PVP has a nano-rod structure and homogeneous size distribution. The nano-rod was about 20 nm in diameter and 200 nm in length. For the UV-visible absorption spectrum of the thin film exhibited an absorption peak at 430 nm, the silver thin film prepared on the surface of the PET substrate was a typical nano-scale sliver film. Measurements of the sliver thin film at room temperature indicated that the silver film was electrically conductive, and the surface resistance was 2.42 k5/cm.

Abstract: We observed the surface resistance of metal thin films by a nondestructive characterization method using a near-field scanning microwave microprobe (NSMM). The NSMM system was coupled to a dielectric resonator with a distance regulation system. To demonstrate the ability of local microwave characterization, the surface resistance dependence of the metallic thin films has been mapped nondestructively.