Multilayer Ceramic Capacitor Thin Electrode Design
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Solution Overview
Problem
Reducing the thickness of internal electrode layers in multilayer ceramic capacitors to achieve downsizing while maintaining high continuity modulus and preventing the diffusion of co-materials into dielectric layers, which lowers the relative dielectric constant.
Innovation Solution
Incorporating a second-phase with an average diameter of 150 nm or less at the interfaces between dielectric and internal electrode layers, and using ceramic grains in the internal electrode layers, along with a manufacturing method involving specific grain size distributions and sintering conditions to suppress co-material diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of internal electrode layers is reduced to achieve downsizing, then the chip size is reduced, but the continuity modulus becomes difficult to achieve at high levels
Solution Approach 1:
The internal electrode layer is constructed as a composite material containing both metal particles (conductive phase) and ceramic particles (insulating phase). This composite structure allows the metal continuous phase to provide high continuity modulus while the ceramic particles prevent excessive grain growth and maintain structural integrity at reduced thicknesses.
Solution Approach 2:
The patent specifies precise parameter ranges: metal particle size of 100 nm or less with standard deviation of 1.5 or less, and ceramic particle size of 10 nm or less with standard deviation of 5 or less. These controlled parameters ensure optimal packing density and continuous metal phase formation, achieving high continuity modulus in thin layers.
2Strength
If co-material is added to internal electrode layers to delay contraction and maintain continuity modulus, then the continuity modulus is improved, but the co-material may diffuse into dielectric layers during sintering, reducing the relative dielectric constant
Solution Approach 1:
A barrier layer is introduced as an intermediary between the internal electrode layer and dielectric layer. This barrier layer prevents diffusion of co-material (ceramic particles) from the internal electrode into the dielectric layer during sintering, thereby maintaining the high relative dielectric constant of the dielectric while allowing the internal electrode to contain co-material for improved continuity modulus.
Solution Approach 2:
The problematic diffusion pathway is separated by extracting the co-material containment function into a distinct barrier layer. This isolates the co-material within the internal electrode structure and prevents its unwanted migration into the dielectric layer, resolving the contradiction between maintaining continuity modulus and preserving dielectric constant.
3Volume of moving object
If the thickness of dielectric layers is reduced to achieve downsizing, then the chip size is reduced, but the relative dielectric constant may be compromised
Solution Approach 1:
The patent specifies that ceramic particles in the dielectric layer have an average size of 10 nm or less with a standard deviation of 5 or less. This fine particle size control increases the density of ceramic grains, enhancing the relative dielectric constant even in thin dielectric layers, while maintaining electrical insulation properties.
Solution Approach 2:
The dielectric layer is formulated as a composite containing ceramic particles with controlled size distribution. This composite structure maximizes the dielectric constant by optimizing particle packing and minimizing voids, allowing thin dielectric layers to maintain high electrical performance.
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
This approach maintains high continuity modulus and relative dielectric constant, prevents crack formation, and enhances the reliability of multilayer ceramic capacitors even with reduced thickness, by effectively managing the distribution and sintering of ceramic and metal components.
Implementation Method 1
a second-phase having an average diameter of 150 nm or less is in at least one of interfaces between the dielectric layers and the internal electrode layers
Implementation Method 2
forming dielectric layers by sintering the ceramic powders of the green sheet
Implementation Method 3
forming internal electrode layers by sintering the metal powders
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer structure in which each of dielectric layers and each of internal electrode layers are alternately stacked, a main component of the dielectric layers being ceramic, wherein: a second-phase has an average diameter of 150 nm or less and is in at least one of interfaces between the dielectric layers and the internal electrode layers; and at least one of the internal electrode layers includes a grain of which a main component is ceramic.