Multilayer Ceramic Capacitor Lower Cover Layer Design
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Solution Overview
Problem
Multilayer ceramic capacitors generate acoustic noise due to piezoelectric vibrations, and increasing the thickness of the lower cover layer to mitigate this can lead to delamination issues, particularly at the boundary surface and longitudinal margin portions.
Innovation Solution
A multilayer ceramic capacitor design with a lower cover layer thicker than the upper cover layer, featuring alternately exposed dummy electrode terminals in the lower cover layer, which reduces delamination and noise by controlling the thickness ratios and deformation rates when voltage is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the lower cover layer is increased to reduce acoustic noise, then the acoustic noise is reduced, but delamination occurs at the boundary surface between the active layer and the lower cover layer
Solution Approach 1:
The patent applies local quality by creating a transition region in the lower cover layer where the thickness gradually changes from the active layer thickness to the maximum lower cover layer thickness. This gradual transition prevents sudden thickness changes that cause delamination, while still maintaining the increased thickness needed for noise reduction in the longitudinal margin portions.
Solution Approach 2:
The lower cover layer is segmented into different thickness regions: a first lower cover layer portion with thickness equal to the active layer thickness (preventing delamination at the boundary), and second lower cover layer portions with greater thickness (reducing acoustic noise). This segmentation allows simultaneous achievement of both noise reduction and delamination prevention.
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
The design effectively reduces acoustic noise while preventing delamination, maintaining capacitance integrity by controlling the thickness ratios and deformation rates within specific ranges, thereby enhancing the reliability of the multilayer ceramic capacitors.
Implementation Method 1
Since these dielectric layers have piezoelectricity properties and electrostrictive properties, a piezoelectric phenomenon may occur and thus cause vibrations between the internal electrodes when AC or DC voltage is applied to the multilayer ceramic capacitor
Implementation Method 2
Since these dielectric layers have piezoelectricity properties and electrostrictive properties, a piezoelectric phenomenon may occur and thus cause vibrations between the internal electrodes when AC or DC voltage is applied to the multilayer ceramic capacitor
Data Source
AI summary
There is provided multilayer ceramic capacitor including, a ceramic body including a plurality of dielectric layers laminated therein, an active layer including a plurality of first and second internal electrodes alternately exposed through both end surfaces of the ceramic body, with the dielectric layers interposed therebetween, and having capacitance formed therein, an upper cover layer formed on an upper portion of the active layer, a lower cover layer formed on a lower portion of the active layer and having a thickness greater than that of the upper cover layer, first and second dummy electrode terminals provided in the lower cover layer to be alternately exposed through both end surfaces of the lower cover layer, and first and second external electrodes covering the both end surfaces of the ceramic body.