Multilayer Ceramic Capacitor Grain Boundary Composition
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in maintaining high reliability while minimizing crystal grain size in the dielectric layer, which can lead to a decrease in dielectric constant and capacitance.
Innovation Solution
A multilayer type electronic component with dielectric layers composed of Ba, Ti, Zr, Hf, and Re, where Re is selected from Gd, Dy, Ho, Er, and Y, featuring crystal grains with first and second regions, and a specific composition that suppresses the decrease in dielectric constant by controlling the median size and cross-sectional areas of the grains, ensuring high reliability even with a small number of crystal grains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of crystal grains is reduced to increase the number of grain boundaries, then reliability is improved, but the dielectric constant decreases due to size effect
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric layer by introducing rare earth elements (Gd, Dy, Ho, Er, or Y) and precisely controlling the ratios of Ba, Ti, Zr, Hf, Si, and Re. This compositional parameter adjustment allows maintaining high dielectric constant even with reduced crystal grain size, thus resolving the contradiction between reliability improvement and dielectric constant maintenance
Solution Approach 2:
The patent creates a composite dielectric material system combining multiple metal elements (Ba, Ti, Zr, Hf) with rare earth elements (Re) and silicon. This composite structure enables the dielectric layer to simultaneously achieve fine grain size for reliability and high dielectric constant through the synergistic effects of different elements, particularly the rare earth elements that enhance dielectric properties at grain boundaries
2Volume of moving object
If the dielectric layer is thinned to reduce size, then integration density is improved, but it becomes difficult to attain reduced crystal grain sizes while securing reliability and maintaining capacitance
Solution Approach 1:
The patent adjusts multiple composition parameters simultaneously - the total amount of Ti+Zr+Hf, the ratio of (Zr+Hf) to (Ti+Zr+Hf), the amount of Si, and crucially the amount of rare earth element Re. These parameter changes enable achieving ultra-thin dielectric layers (≤0.5 μm) while maintaining appropriate crystal grain sizes for reliability, as the compositional optimization compensates for the reduced thickness
Solution Approach 2:
The patent creates local compositional variations within the dielectric layer, particularly concentrating rare earth elements at grain boundaries and interfaces. This local quality enhancement ensures that even in ultra-thin layers with fewer grain boundaries, the critical regions have optimized properties for both reliability and capacitance maintenance
3Ease of manufacture
If the number of crystal grains is small in the thickness direction, then manufacturing is simplified, but reliability cannot be secured
Solution Approach 1:
The patent changes the chemical composition to include specific amounts of rare earth elements (0.5≤c≤10.0 when Ti+Zr+Hf=100) and optimizes the Ba:Re ratio (0.990≤m≤1.050). These parameter changes ensure that even with a small number of crystal grains in ultra-thin dielectric layers, the reliability is maintained through enhanced grain boundary properties and reduced defect formation
Solution Approach 2:
The rare earth elements act as intermediaries that mediate between the crystal grains and grain boundaries in ultra-thin dielectric layers. They accumulate at grain boundaries to improve adhesion and reduce defects, compensating for the reduced number of grain boundaries and ensuring reliability even when manufacturing produces fewer crystal grains
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 solution ensures high reliability and maintains capacitance by controlling the median size and distribution of crystal grains, achieving an average thickness of dielectric layers less than 0.5 μm and a coefficient of variation in thickness less than 15%, resulting in a mean time to failure of 50 hours or more under high temperature load tests.
Implementation Method 1
Each of the plurality of laminated dielectric layers has a plurality of crystal grains with first regions and second regions, each of the first regions having the Re dissolved in a solid state
Data Source
AI summary
A multilayer electronic component having a plurality of laminated dielectric layers and inner electrode layers. The dielectric layers have a plurality of crystal grains including first regions where Re is dissolved in a solid state; and second regions where Re is not dissolved in the solid state. A median size of the crystal grains to an average thickness of the dielectric layers is 0.5≤t≤0.7. A ratio of a sum of cross sectional areas of the first regions to those of the plurality of crystal grains is 0.7≤s≤0.9. When a total amount of Ti, Zr, and Hf is 100 molar parts in the dielectric layers, a sum of the Zr and the Hf is 0≤a≤1.0; an amount b of Si is 0.1≤b≤1.0; an amount c of Re is 0.5≤c≤10.0; and a ratio m of a total of Ba and Re to a total of Ti, Zr, and Hf is 0.990≤m≤1.050.