Monolithic Ceramic Capacitor Grain Boundary Insulation
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Solution Overview
Problem
Monolithic ceramic capacitors with reduced dielectric ceramic layer thickness face challenges in maintaining adequate insulation properties and life characteristics due to issues at grain boundaries, particularly when the thickness is less than 1 μm.
Innovation Solution
A monolithic ceramic capacitor design featuring dielectric ceramic layers with a perovskite-type compound as the main component, incorporating Mn and V as auxiliary components, and controlling their content to enhance insulation properties and life characteristics, while maintaining a reduced volume ratio of grain boundaries, thereby ensuring uniform diffusion and preventing segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of dielectric ceramic layers is reduced to less than 1 μm to reduce capacitor size, then the capacitance increases and size is reduced, but the insulation property and life characteristic deteriorate due to increased electric field stress and grain boundary issues
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric ceramic by incorporating specific auxiliary components (Mn: 0.05-0.75 molar parts, V: 0.05-0.75 molar parts, total 0.10-0.80 molar parts per 100 molar parts of main component) to improve grain boundary insulation. This compositional parameter change enables the ceramic to maintain high reliability even at ultra-thin layer thicknesses of less than 1 μm, resolving the contradiction between size reduction and reliability maintenance.
Solution Approach 2:
The patent creates a composite dielectric ceramic material by combining the main component (Ba or Ba with Ca/Sr, and Ti or Ti with Zr/Hf) with auxiliary components (Mn, V, and optionally rare-earth elements, Mg, Si). This composite material structure leverages the beneficial effects of each component: the main component provides dielectric properties while the auxiliary components specifically enhance grain boundary insulation and life characteristics, enabling ultra-thin layers to achieve both small size and high reliability.
2Quantity of substance
If the thickness of dielectric ceramic layers is reduced, then the capacitance increases, but the electric field applied to the dielectric ceramic layers increases, requiring better insulation property and life characteristic
Solution Approach 1:
The patent modifies the chemical composition parameters by adding specific auxiliary components (Mn and V within defined ranges) that specifically address grain boundary insulation. This parameter change enables the dielectric ceramic to withstand higher electric field stress resulting from ultra-thin layer construction, allowing the capacitor to achieve high capacitance while maintaining reliability under increased electric field conditions.
3Reliability
If the content of auxiliary components Mn and V is increased to enhance insulation property, then the grain boundary insulation improves, but segregation may occur affecting life characteristic
Solution Approach 1:
The patent precisely defines optimal parameter ranges for auxiliary components (Mn: 0.05-0.75 molar parts, V: 0.05-0.75 molar parts, total: 0.10-0.80 molar parts per 100 molar parts of main component) to achieve the best balance between grain boundary insulation and compositional stability. This optimized parameter setting ensures sufficient insulation improvement while preventing segregation, and the patent includes specific provisions for uniform mixing and controlled sintering to maintain compositional homogeneity.
Data Source
AI summary
A monolithic ceramic capacitor includes dielectric ceramic layers having a thickness of less than 1 μm. When this thickness is t and the crystal grains of a dielectric ceramic of the layers have a mean diameter of r, a mean number N of grain boundaries satisfies 0<N≦2 where N=t/r−1. The dielectric ceramic contains, as a main component, a perovskite type compound ABO3 (where A is Ba or Ba and at least one of Ca and Sr, B is Ti or Ti and at least one of Zr and Hf), and further contains Mn and V as auxiliary components. On the basis of 100 molar parts of the main component, the content of Mn is 0.05 to 0.75 molar parts, the content of V is 0.05 to 0.75 molar parts, and the total content of Mn and V is 0.10 to 0.80 molar parts.