Multilayer Ceramic Capacitor Electrode Structure for Acoustic Noise Reduction
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Solution Overview
Problem
Multilayer ceramic capacitors generate 'acoustic noise' due to piezoelectric and electrostrictive properties of dielectric layers, which is not effectively suppressed by increasing the thickness of the lower outer layer portion, as this impairs reduction in size and increase in capacitance.
Innovation Solution
Adjusting the coverage of the main component metal in the lower internal electrode layer by using solid solution layers with a higher concentration of a subcomponent metal at interfaces between the internal electrode layers and dielectric layers, allowing for reduced 'acoustic noise' without significant thickness increase or capacitance reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the lower outer layer portion is increased to suppress acoustic noise, then acoustic noise is reduced, but the reduction in thickness (reduction in size) and increase in capacitance are significantly impaired
Solution Approach 1:
The patent applies local quality by creating asymmetric thickness distribution of the outer layer portions, specifically making the lower outer layer portion thicker than the upper outer layer portion. This localized structural modification targets the specific region where vibration suppression is needed while minimizing the overall thickness increase of the capacitor.
Solution Approach 2:
The patent employs asymmetry by intentionally designing the lower outer layer portion with greater thickness compared to the upper outer layer portion. This asymmetric structure creates a mechanical imbalance that suppresses vibrations and acoustic noise generation, resolving the contradiction between noise reduction and size reduction.
2Object-affected harmful factors
If the thickness of the lower outer layer portion is increased to suppress acoustic noise, then acoustic noise is reduced, but the increase in capacitance is significantly impaired
Solution Approach 1:
By localizing the thickness increase to only the lower outer layer portion rather than uniformly increasing the entire capacitor thickness, the patent minimizes the impact on capacitance while achieving acoustic noise suppression. The asymmetric design allows the thicker lower portion to serve as a vibration damper without proportionally reducing the volume available for capacitance-generating dielectric layers.
Solution Approach 2:
The asymmetric thickness distribution allows the lower outer layer portion to function as a vibration suppression element while preserving more volume for the inner layer portion containing dielectric and electrode layers, thereby maintaining higher capacitance compared to a symmetric design with the same overall thickness constraint.
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
Effectively reduces or prevents 'acoustic noise' in multilayer ceramic capacitors while maintaining their size reduction and capacitance increase, by optimizing the internal electrode layer composition and structure.
Implementation Method 1
since such dielectric layers have piezoelectricity and an electrostrictive property, stress and mechanical strain are generated when an electric field is applied
Implementation Method 2
since such dielectric layers have piezoelectricity and an electrostrictive property, stress and mechanical strain are generated when an electric field is applied
Data Source
AI summary
A multilayer ceramic capacitor includes dielectric layers and internal electrode layers. Internal electrode layers adjacent to a first main surface define first main surface-side internal electrode layers, and internal electrode layers adjacent to the second main surface define second main surface-side internal electrode layers, first solid solution layers including a second metal as a solid solution is provided at interfaces between the first main surface-side internal electrode layers and the dielectric layers, the interfaces being in the first main surface-side internal electrode layers, and second solid solution layers including the second metal as a solid solution is provided at interfaces between the second main surface-side internal electrode layers and the dielectric layers, the interfaces being in the second main surface-side internal electrode layers. A concentration of the second metal in the second solid solution layer is higher than that of the second metal in the first solid solution layer.