Dielectric Ceramic Composition for Multilayer Capacitors
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Solution Overview
Problem
Existing dielectric ceramic compositions for multilayer ceramic capacitors face challenges in achieving high specific permittivity and maintaining temperature characteristics and insulation resistance when dielectric layers are made thinner, leading to significant changes in capacitance over time.
Innovation Solution
A dielectric ceramic composition is developed using barium titanate with rare earth elements divided into two groups based on effective ionic radius, where oxides of these elements are added in specific ratios to improve specific permittivity and temperature characteristics, and additional subcomponents like MgO, SiO2, and V2O5 are included to enhance sinterability and capacitance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dielectric layers are made thinner to downsize multilayer ceramic capacitors, then the capacity increases, but the change of specific permittivity with time becomes remarkably large
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by incorporating specific rare earth elements (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium) in controlled amounts (0.1-10 wt%) into the barium titanate base material. This compositional parameter change stabilizes the specific permittivity over time even when dielectric layers are made thinner, thereby maintaining reliability while enabling downsizing.
2Volume of moving object
If dielectric layers are made thinner to achieve downsizing, then the capacity increases, but the temperature characteristic of capacitance deteriorates
Solution Approach 1:
The patent modifies the dielectric ceramic composition by adding rare earth elements that stabilize the perovskite crystal structure across a wide temperature range. These elements adjust the Curie temperature and broaden the stable temperature range, ensuring that capacitance temperature characteristics remain stable even when dielectric layers are thinned for downsizing applications.
3Volume of moving object
If dielectric layers are made thinner to increase capacity, then the device size decreases, but the insulation resistance accelerated lifetime becomes shorter
Solution Approach 1:
The patent changes the chemical composition by incorporating rare earth elements that passivate grain boundaries and reduce defect states in the dielectric ceramic structure. This compositional modification suppresses leakage current and stabilizes insulation resistance over time, thereby extending the accelerated lifetime even when dielectric layers are made thinner for capacity enhancement.
4Quantity of substance
If specific permittivity is increased to achieve larger capacity, then the capacity increases, but the manufacturing complexity increases
Solution Approach 1:
The patent combines multiple rare earth elements with complementary properties into a single dielectric ceramic composition system based on barium titanate. This merging approach achieves high specific permittivity through synergistic effects while maintaining a unified manufacturing process, avoiding the need for separate processing steps for different functional materials and thereby controlling manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves high specific permittivity, improved temperature characteristics, and extended insulation resistance, allowing for thinner dielectric layers while maintaining performance, thus addressing the challenges of capacitance stability and reliability.
Implementation Method 1
a main component comprised of barium titanate, a fourth subcomponent comprised of an oxide of R1 (note that R1 is at least one kind selected from a first element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of less than 108pm)
Implementation Method 2
divided into two groups based on a value of effective ionic radius for coordination number 9
Implementation Method 3
extended insulation resistance, allowing for thinner dielectric layers while maintaining performance
Data Source
Figure 1
AI summary
A production method of a dielectric ceramic composition, comprising a main component comprised of barium titanate, a fourth subcomponent comprised of an oxide of R1 (note that R1 is at least one kind selected from a first element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of less than 108pm), and a fifth subcomponent comprised of an oxide of R2 (note that R2 is at least one kind selected from a second element group composed of rare earth elements having a value of effective ionic radius for coordination number 9 of 108pm to 113pm); comprising the steps of obtaining a post-reaction material by bringing the main component material reacting with a part of the fourth subcomponent material and/or a part of the fifth subcomponent material, and adding remaining materials of the fourth subcomponent and the fifth subcomponent to be included in the dielectric ceramic composition to the post-reaction material; wherein a ratio M1/M2 of the number of moles M1 of R1 of the fourth subcomponent and the number of moles M2 of R2 of the fifth subcomponent in the finally obtained dielectric ceramic composition satisfies 4 < M1/M2 ≤ 100: by which specific permittivity and temperature characteristic of capacitance can be balanced even when the dielectric layers are made thin.