Multilayer Ceramic Capacitor Grain Control for Insulation Stability
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Solution Overview
Problem
Multilayer ceramic capacitors with high dielectric ceramic layers face significant aging variation in insulation resistance during high temperature load tests, leading to reliability issues due to the material composition used in prior art.
Innovation Solution
A multilayer ceramic capacitor design incorporating a Ba and Ti containing perovskite compound with La, Mg, and Mn, where the molar ratios of La, Mg, and Mn relative to Ti are controlled between 1.2 to 6.0, 0.5 to 5.0, and 1.0 to 3.0 respectively, and the average number of crystal grains in each dielectric layer is reduced to three or less, enhancing insulation deterioration tolerance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-reducible dielectric ceramic composition with high relative dielectric constant is used to thin the dielectric layer, then the capacitance-temperature characteristics are improved and the dielectric layer can be made thinner, but the aging variation in insulation resistance in high temperature load test becomes great, making it impossible to obtain a multilayer ceramic capacitor with sufficient reliability
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by introducing specific amounts of MnO (0.3-1.5 parts by weight) and oxide glass (0.5-2.5 parts by weight) containing BaO, SrO, Li2O, and SiO2 into the non-reducible dielectric ceramic composition. This modifies the material properties to reduce aging variation in insulation resistance while maintaining the thin dielectric layer structure, thereby resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
The patent creates a composite dielectric ceramic material by combining the base non-reducible dielectric ceramic (BaTiO3 with rare earth oxide) with MnO and oxide glass components. This composite structure leverages the high dielectric constant of the base material while the added components suppress aging effects, enabling both thin dielectric layers and high reliability simultaneously.
2Volume of moving object
If the dielectric layer is thinned to achieve compact capacitor size, then the capacitor becomes smaller and lighter, but the insulation resistance deteriorates in high temperature load tests, reducing reliability
Solution Approach 1:
The patent modifies the compositional parameters of the dielectric ceramic by adding MnO and oxide glass in controlled amounts. This enables the use of extremely thin dielectric layers while maintaining insulation resistance stability through the protective effect of the added components against high temperature degradation.
Solution Approach 2:
The patent employs a composite dielectric ceramic formulation that combines the high dielectric constant material with MnO and oxide glass. This composite structure provides both the thinness required for compact size and the thermal stability needed to prevent insulation resistance deterioration, simultaneously achieving small volume and high reliability.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including a plurality of stacked dielectric layers including a dielectric ceramic that includes a plurality of crystal grains and a plurality of internal electrodes disposed at a plurality of interfaces between the dielectric layers, and external electrodes. The multilayer body includes a Ba and Ti containing perovskite compound, La, Mg and Mn, and satisfies conditions such that in a case in which a content of Ti is set to 100 molar parts, a fraction of each content of La, Mg and Mn relative to the content of Ti is such that La is about 1.2 to about 6.0 molar parts, Mg is about 0.5 to about 5.0 molar parts and Mn is about 1.0 to about 3.0 molar parts, and an average number of crystal grains included in each of the dielectric layers in the stacking direction is one or more to three or less.