Multilayer Capacitor Insulating and Buffer Layers for Acoustic Noise Reduction
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) generate acoustic noise due to piezoelectric vibrations when a DC or AC voltage is applied, which is undesirable in electronic devices, particularly in those with voice communication functions like smartphones.
Innovation Solution
A multilayer capacitor design featuring a capacitor body with alternately stacked dielectric layers and internal electrodes, an insulating layer, a buffer layer, and terminal electrodes to absorb and reduce piezoelectric vibrations, thereby minimizing acoustic noise. The insulating layer primarily absorbs vibrations, and the buffer layer further reduces these vibrations by providing high rigidity and minimal deformation, ensuring minimal noise transmission to the board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multilayer capacitor is used to achieve high capacitance in a small size, then the capacitance density is improved, but piezoelectric vibrations generate acoustic noise
Solution Approach 1:
An insulating layer is introduced as an intermediary between the capacitor body and the buffer layer. This insulating layer absorbs piezoelectric vibrations generated by the capacitor, preventing direct transmission to the buffer layer and reducing acoustic noise while maintaining the high capacitance density of the MLCC structure
Solution Approach 2:
The patent employs a composite structure combining the capacitor body, insulating layer, and buffer layer with different material properties. The insulating layer has high vibration absorption capability, while the buffer layer provides structural support with high rigidity, creating a composite system that reduces acoustic noise without sacrificing capacitance performance
2Device complexity
If the capacitor body is directly mounted on the board, then the device complexity is reduced, but vibration transmission to the board increases
Solution Approach 1:
The insulating layer serves as a vibration-absorbing intermediary between the capacitor body and the buffer layer, reducing piezoelectric vibrations before they reach the mounting structure. This intermediary layer minimizes vibration transmission to the board while adding minimal structural complexity
Solution Approach 2:
The insulating layer is positioned beforehand between the capacitor body and the buffer layer to cushion and absorb vibrations before they can be transmitted to the board. This prior cushioning approach prevents vibration transmission at the source rather than attempting to mitigate it after transmission occurs
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 solution effectively reduces piezoelectric vibrations and subsequent acoustic noise, enhancing the low noise design of electronic products by absorbing vibrations through the insulating and buffer layers, resulting in a quieter operation.
Implementation Method 1
an insulating layer formed in the first surface of the capacitor body... The insulating layer primarily absorbs vibrations
Implementation Method 2
a buffer layer covering the insulating layer... the buffer layer further reduces these vibrations by providing high rigidity and minimal deformation
Implementation Method 3
Since the dielectric layer has piezoelectric and piezoresistive properties, when a direct current (DC) or alternating current (AC) voltage is applied to an MLCC, a piezoelectric phenomenon may occur between the internal electrodes, resulting in vibrations
Data Source
AI summary
A multilayer capacitor includes a capacitor body, dielectric layers and a plurality of first internal electrodes and second internal electrodes forming a portion of the capacitor body, the plurality of first internal electrodes and second internal electrodes alternately disposed with respective dielectric layers interposed therebetween, the capacitor body further having a first surface and a second surface opposing each other, a third surface and a fourth surface opposing each other, and a fifth surface and a sixth surface opposing each other, the first internal electrodes and the second internal electrodes being exposed through at least the third surface and the fourth surface, respectively, an insulating layer disposed in the first surface of the capacitor body, a buffer layer at least partially covering the insulating layer, and a first terminal electrode and a second terminal electrode spaced apart from each other.