Papers by Keyword: MLCC

Abstract: Multilayer ceramic capacitors (MLCC) have wide application in electronic due to its electrical characteristics: low equivalent series resistance (ESR) and high volume efficiency. One of the MLCC manufacturing problems is the choice of composition for the end pastes. The experimental results of the termination pastes composition influence on the quality high-voltage MLCC investigation are presented. The causes of the defects appearance in the termination are determined, the composition of the termination paste, which ensures the quality contact of the internal electrode with the external, is proposed.

Abstract: Two different BaTiO₃ (160nm) nanopowders coated with Y and with Dy were fabricated by an aqueous chemical coating method, and their dielectric properties and microstructures were investigated with X-ray diffraction, Impedance analyzer, SEM and TEM. Y and Dy were coated on the BaTiO₃ powder using nitrates. Coated BaTiO₃ powders were pressed in a disk shape and sintered at 1150~1200°C for 2 hours in reduced atmosphere of 10%H₂ - 90%N₂. Coating layer of the BaTiO₃ particle was thin with a thickness of 3 ~ 5nm. Coated BaTiO₃ sintered sample exhibited a larger lattice parameter (a, c) and smaller tetragonality (c/a) than pure BaTiO₃ one. Y coated BaTiO₃ sample sintered at 1200°C showed good dielectric properties with a high dielectric constant of around 2000 and a stable temperature coefficient of capacitance (TCC).

Abstract: We present the technology of the solid solution with formula (1-y)[(1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃]-yPb(Fe_1/2Nb_1/2)O₃ where x=0.25, y=0.1 i.e. 0.9(0.75PMN-0.25PT)-0.1PFN. The addition of PFN decreases the temperature of final sintering and as a result such composition is interesting material for multilayer ceramic capacitors (MLCC). The powder of 0.9(0.75PMN-0.25PT)-0.1PFN has been obtained in three steps. In first step we obtained MgNb₂O₆. In second step FeNbO₄ was obtained. In final third step the 0.9(0.75PMN-0.25PT)-0.1PFN was obtained from mixed powders MgNb₂O₆, FeNbO₄ and PbO and TiO₂. For obtained ceramics the following investigations have been made: XRD patterns, microstructure, EDS and main dielectric properties v.s. temperature. It has been stated that obtained ceramic powder is a good material for obtaining MLCC

Abstract: We performed first-principles calculations to examine the interaction among rare-earth (RE), alkaline-earth (AE) elements and oxygen vacancy (V_O) in BaTiO₃, in order to clarify the combined effects of V_O trapping by two different elements. It was found that there is a synergistic effect of V_O trapping by RE at Ba site and AE at Ti site, so that the co-doping is effective to improve insulating reliability of BaTiO₃. We also verified that the local atomic structures around dopants obtained by calculations well agree with that obtained experimentally by extended X-ray absorption fine structure (EXAFS) analyses. The present work is the first one to clarify the structural environment around dopants including V_O by both theoretical and experimental approaches.

Abstract: When designing the capacitance of a Multi-Layer Ceramic Capacitor (MLCC), engineers used to focus on the way to find appropriate combination of the design parameters. These design parameters usually include materials, layer numbers and thicknesses of the electrodes and the dielectrics. However, not considering the mechanical strength in the design stage may lead the manufactured MLCC prototypes to fail in material test, and a redesign is very often needed. Such a design-and-redesign process is inefficient and needs to be improved. The present paper proposes a simple and efficient design approach to replace the traditional one. It first identifies an empirical equation correlating the capacitance of a MLCC to the design parameters based on specifications. The strength of the MLCC can be evaluated in advance with the help of mechanics of material. A design platform which considers simultaneously the capacitance and the material strength under various design parameters can be established. Demonstration of a MLCC design by the developed platform indicates the proposed approach does help engineers improving and speeding their designs.