Laminated electronic components such as laminated ceramic capacitors are widely used as compact, large-capacity and highly reliable electronic components. As electronic circuits have reached higher density in recent years, there has been an increasingly strong demand for miniaturization of dielectric elements. Furthermore, as miniaturization and increased capacity of laminated electronic components such as laminated ceramic capacitors have sharply advanced, so the range of applications has also expanded. As the range of applications of laminated electronic components has expanded, various characteristics have come to be required of these laminated electronic components.
For example, medium- and high-voltage capacitors which are used in devices such as engine control modules (ECMs), fuel injection devices, electronic control throttles, inverters, converters, high-intensity discharge (HID) headlamp units, hybrid engine battery control units and digital still cameras often have a rated voltage in excess of 100 V because they are used in circuits for providing a high voltage boost. Medium- and high-voltage capacitors such as these need a high dielectric constant and high capacitance when a high DC bias is applied. Furthermore, when these medium- and high-voltage capacitors are used in a motor vehicle or industrial equipment etc., there is also a need for a high dielectric constant and high capacitance not only for application of a high DC bias but also for use under a high-temperature environment.
However, conventional dielectric compositions are designed on the assumption that they will be used when a low DC bias is applied. This means that if an electronic component having a dielectric layer comprising a conventional dielectric composition is used when a high DC bias is applied, there is a problem in that the dielectric constant and the capacitance are reduced. This problem becomes more marked the higher the DC bias, especially in laminated ceramic capacitors which have very thin layers, because the dielectric constant and capacitance tend to decrease.
In order to solve the abovementioned problem, Japanese patent document JP 3334607 B2 mentioned below describes a dielectric porcelain composition which contains a main component comprising: barium titanate having an alkali metal oxide content of 0.02 wt % or less; at least one compound selected from among europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, and ytterbium oxide; barium zirconate, magnesium oxide and manganese oxide, said main component being represented by the following compositional formula: {BaO}mTiO2+αR2O3+βBaZrO3+γMgO+gMnO (where R2O3 is at least one compound selected from among Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3; and α, β, γ, and g represent a mole ratio and are within the following ranges: 0.001≤α≤0.06, 0.005≤β≤0.06, 0.001<γ≤0.12, 0.001<g≤0.12, γ+g≤0.13, and 1.000<m≤1.035); and said dielectric composition contains, as an auxiliary component, silicon oxide in an amount of 0.2-5.0 mol as SiO2 equivalent, with respect to 100 mol of the main component.
A dielectric porcelain composition such as that described in Japanese patent document JP3334607 B2 has a relatively large dielectric constant when a DC bias of 5 V/μm is applied. However, it is not possible to achieve satisfactory characteristics with the dielectric porcelain composition described in Japanese patent document JP3334607 B2 in a laminated electronic component having thinner layers in order to respond to an even greater degree of compactness and higher capacity in a medium- and high-voltage capacitor. It is not possible to achieve a high dielectric constant when a high DC bias of the order of 8 V/μm is applied at room temperature to the dielectric porcelain composition described in Japanese patent document JP 3334607 B2. In addition, a high dielectric constant cannot be achieved when a high DC bias of the order of 8 V/μm is applied at high temperature.
Furthermore, there is a possibility of breakdown of the dielectric composition occurring in a conventional dielectric composition due to the application of a high DC bias. A superior withstand field that does not produce breakdown is also required for when a high DC bias is applied.