Multilayer Ceramic Capacitor Internal Electrode Grain Control
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Solution Overview
Problem
The reduction in thickness of dielectric and internal electrode layers in multilayer ceramic capacitors leads to a lower continuity modulus due to differences in sintering temperatures between metal and ceramic components, making it difficult to maintain high dielectric properties and capacity.
Innovation Solution
Incorporating ceramic grains with a diameter of 40% or more of the average thickness of the internal electrode layers, and using a metal conductive paste with a sharp grain size distribution, along with ceramic co-materials, to suppress excessive sintering and diffusion during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thicknesses of dielectric layers and internal electrode layers are reduced to downsize the capacitor, then the chip size is reduced, but the continuity modulus of internal electrode layers becomes lower
Solution Approach 1:
The invention changes the grain size parameter of the co-material to 10 nm or less (standard deviation of 5 or less), which is significantly finer than conventional co-materials. This parameter change allows the co-material to remain dispersed in the internal electrode layer without excessive diffusion into dielectric layers, thereby maintaining continuity modulus even when layer thicknesses are reduced for downsizing.
Solution Approach 2:
The invention uses a composite conductive paste containing both metal powders (main component) and ceramic co-materials in specific grain size distributions. This composite structure allows the fine co-material to suppress metal powder sintering and contraction while the sharp grain size distribution prevents excessive diffusion, resolving the contradiction between downsizing and maintaining reliability.
2Reliability
If ceramic co-material is added to internal electrode layers to delay contraction, then the continuity modulus is improved, but the co-material diffuses to dielectric layers during sintering
Solution Approach 1:
The invention changes the grain size parameter of the co-material to 10 nm or less with a standard deviation of 5 or less. This ultra-fine grain size with sharp distribution creates a large number of grain boundaries that act as barriers to diffusion, preventing co-material from migrating into dielectric layers while still providing contraction delay functionality in the internal electrode layer.
Solution Approach 2:
The invention creates local quality differences by having the fine co-material predominantly distributed in the internal electrode layer rather than diffusing uniformly throughout the structure. The sharp grain size distribution ensures that co-material remains localized where it is needed (in the internal electrode layer) without contaminating dielectric layers, thus maintaining both continuity modulus and compositional stability.
3Volume of moving object
If the thickness of internal electrode layers is reduced, then the chip size is reduced, but the continuity modulus is further reduced
Solution Approach 1:
The invention changes multiple parameters simultaneously: the co-material grain size to 10 nm or less, the metal powder grain size to 100 nm or less, and the thickness ratio of internal electrode layer to dielectric layer to 1/30 or more. These coordinated parameter changes enable maintaining continuity modulus even when internal electrode layer thickness is reduced to 30 nm or less, achieving both downsizing and manufacturing precision.
Solution Approach 2:
The invention employs a composite conductive paste with specifically controlled grain size distributions for both metal powders and co-materials. This composite approach allows the fine co-material to provide structural support and delay contraction in the thinned internal electrode layer, preventing continuity modulus degradation while enabling further miniaturization of the capacitor chip.
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 enhances the continuity modulus of internal electrode layers, maintains desirable dielectric properties, and achieves a higher capacity by preventing excessive sintering and diffusion of co-materials into dielectric layers.
Implementation Method 1
a second step of forming internal electrode layers by sintering the metal powders and forming dielectric layers by sintering the ceramic powders of the green sheet
Implementation Method 2
forming internal electrode layers by sintering the metal powders and forming dielectric layers by sintering the ceramic powders of the green sheet
Implementation Method 3
The co-material tends to diffuse to the dielectric layers in the sintering
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, a main component of the internal electrode layers being a metal, wherein: at least one of the internal electrode layers includes a grain of which a main component is ceramic; and the grain has a diameter of 40% or more of an average thickness of the at least one of the internal electrode layers.