Multi-layer ceramic capacitor and method of manufacturing the same
AssigneeTaiyo Yuden Co., Ltd.
InventorsKoichiro MORITA, Youichi MIZUNO
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Abstract
A multi-layer ceramic capacitor is constituted by ceramic dielectric layers alternately laminated with conductive layers, wherein the ceramic dielectric layers are sintered in such a way that core-shell grains having a core-shell structure are mixed with uniform solid-solution grains resulting from uniform progression of the solid solution process. Such multi-layer ceramic capacitor is characterized in that the area ratio of the core-shell grains to all sintered grains constituting the ceramic dielectric layer is 5 to 15% and that the average grain size of all sintered grains including the core-shell grains and uniform solid-solution grains is 0.3 to 0.5 μm.
Claims5
A multi-layer ceramic capacitor constituted by ceramic dielectric layers alternately laminated with conductive layers, wherein:
- each of the ceramic dielectric layers is constituted by sintered grains comprised of core-shell grains each having a core-shell structure wherein a core of primary component is enclosed by a shell of auxiliary solid-solution component, and uniform solid-solution grains each constituted by solid solution without a core;
- an area ratio of the core-shell grains to all the sintered grains constituting each ceramic dielectric layer is 5 to 15% as measured in an observed area of cross section by a transmission electron microscope (TEM) of a randomly selected portion of the ceramic dielectric layer with interposing conductive layers;
- and
- a grain size representing an average grain size of all the sintered grains including the core-shell grains and uniform solid-solution grains is 0.3 to 0.5 μm.
A method of manufacturing a multi-layer ceramic capacitor constituted by ceramic dielectric layers alternately laminated with conductive layers, comprising:
- a step to mix a primary component powder of a first grain size constituted by relatively small-sized grains, with a primary component powder of a second grain size constituted by relatively large-sized grains, at a specified blending ratio;
- a step to add an auxiliary solid-solution component powder to the primary component powders of the first grain size and second grain size, to prepare a dielectric material powder;
- a step to prepare a green sheet by coating the dielectric material powder;
- a step to place a conductive paste on the green sheet to form electrode patterns corresponding to two electrodes, one on the left and the other on the right, respectively;
- a step to laminate the green sheets in such a way that the electrode patterns of the left and right electrodes alternate;
- and
- a step to sinter the green sheet laminate in such a way that an area ratio of core-shell grains to all sintered grains constituting the ceramic dielectric layer falls between 5 and 15% and that an average grain size of all sintered grains including the core-shell grains and uniform solid-solution grains falls between 0.3 and 0.5 μm.
Dependencies are inferred from the claim text.