Multilayered Ceramic Capacitor Noise Reduction via Dummy Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multilayered ceramic capacitors generate acoustic noise due to piezoelectric vibrations when mounted on printed circuit boards, and existing measures to reduce this noise are insufficient.
Innovation Solution
A multilayered ceramic capacitor design featuring a ceramic body with alternating internal electrodes, external electrodes, dummy electrodes, and piezoelectric members with a higher dielectric constant, where the thickness ratios of the cover layers and active layer are optimized to minimize vibration transfer to the circuit board, and the inclusion of dummy patterns and piezoelectric members within the lower cover layer to offset expansion and shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a multilayered ceramic capacitor is mounted on a printed circuit board with internal electrodes having directivity perpendicular to the board, then acoustic noise is reduced compared to horizontal mounting, but a predetermined level of noise remains and further reduction is required
Solution Approach 1:
The patent introduces dummy electrodes as intermediary elements between the internal electrodes and the external electrodes. These dummy electrodes serve as mediators that absorb and dissipate the piezoelectric vibrations, preventing them from being transmitted to the external electrodes and ultimately to the printed circuit board. This intermediary structure effectively reduces acoustic noise while maintaining the capacitor's electrical functionality.
Solution Approach 2:
The patent modifies the physical parameters of the capacitor structure by adding dummy electrodes with specific dimensions and positions. By changing the structural parameters (length, width, position of dummy electrodes), the vibration characteristics are altered to reduce acoustic noise emission while maintaining the perpendicular mounting orientation that already provides some noise reduction.
2Object-affected harmful factors
If piezoelectric members with higher dielectric constant are added to connect internal electrodes and dummy electrodes, then vibration is reduced, but device complexity increases
Solution Approach 1:
The piezoelectric members serve multiple functions simultaneously: they provide electrical connection between internal and dummy electrodes, they act as vibration dampers due to their piezoelectric properties, and they contribute to the overall capacitance of the device. This multi-functionality reduces vibration effectively while minimizing the increase in device complexity, as the same components perform multiple roles.
3Object-affected harmful factors
If dummy electrodes are extended from external electrodes toward the inner portion to oppose internal electrodes, then acoustic noise is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The dummy electrodes are pre-configured with specific dimensions and positions during the manufacturing process to predetermined values that are optimized for noise reduction. By establishing these parameters in advance (preliminarily), the actual manufacturing tolerances can be relaxed, as the noise reduction effect is achieved within a defined parameter range rather than requiring extremely precise positioning.
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
Significantly reduces acoustic noise by offsetting the expansion and shrinkage of external electrodes, resulting in lower noise levels and improved capacitor performance.
Implementation Method 1
a plurality of piezoelectric members connecting the first internal electrode and the first dummy electrode or the second internal electrode and the second dummy electrode, respectively, inside the active layer, the piezoelectric members having a higher dielectric constant than the dielectric layer
Implementation Method 2
Since dielectric layers have piezoelectric properties and electrostrictive properties, a piezoelectric phenomenon may occur, thus causing vibrations among the internal electrodes when alternating current (AC) or direct current (DC) voltage is applied to the multilayered ceramic capacitor
Implementation Method 3
Since dielectric layers have piezoelectric properties and electrostrictive properties, a piezoelectric phenomenon may occur, thus causing vibrations among the internal electrodes
Data Source
AI summary
There is provided a multilayered ceramic capacitor, including a ceramic body, an active layer including a plurality of first and second internal electrodes alternately exposed through both end surfaces of the ceramic body while having the dielectric layer therebetween, to form capacitance; upper and lower cover layers formed above and below the active layer; first and second external electrodes covering both end surfaces of the ceramic body; a plurality of first and second dummy electrodes extended from the first and second external electrodes; and a plurality of piezoelectric members connecting the first internal electrode and the first dummy electrode or the second internal electrode and the second dummy electrode, inside the active layer, the piezoelectric members having a higher dielectric constant than the dielectric layer.