Multilayer Capacitor Insulating Layer Acoustic Noise Reduction
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Solution Overview
Problem
Multilayer ceramic capacitors generate acoustic noise due to piezoelectric vibrations, which cause discomfort and are a concern in electronic devices with voice communication functions, such as smartphones, as they radiate vibratory sound across a wide audio frequency range.
Innovation Solution
A multilayer capacitor design with a capacitor body featuring alternately disposed first and second internal electrodes, dielectric layers, and external electrodes, along with an insulating layer and terminal electrodes, is implemented to reduce piezoelectric vibrations by minimizing the area of piezoelectric activity on the mounting surface, thereby reducing acoustic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer capacitor is used to provide compactness and high capacitance, then the capacitor can be effectively mounted on printed circuit boards, but piezoelectric vibrations occur between internal electrodes causing acoustic noise
Solution Approach 1:
An insulating layer is introduced as an intermediary between the internal electrodes and the external environment. This insulating layer absorbs and dampens the piezoelectric vibrations generated between internal electrodes, preventing them from being transmitted to external electrodes and radiating as acoustic noise, while the capacitor maintains its full capacitance performance
Solution Approach 2:
The harmful piezoelectric vibration effect is extracted and isolated from the main capacitor structure by confining it within the insulating layer. The vibration energy is captured and dissipated locally rather than being transmitted outward, separating the useful capacitance function from the harmful noise generation
2Ease of manufacture
If the capacitor body structure is simplified for ease of manufacture, then production cost is reduced, but the area of piezoelectric activity on the mounting surface increases causing more noise
Solution Approach 1:
The insulating layer is applied selectively to specific regions of the capacitor body where piezoelectric activity occurs. By concentrating the noise-reducing insulating material only in the areas where internal electrodes are exposed and vibrations are generated, the design achieves effective noise reduction without unnecessarily complicating the overall manufacturing process
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 by minimizing vibrations transferred to the substrate, enhancing the reliability of the capacitor and improving the low noise design of electronic products by absorbing piezoelectric vibrations through the insulating layer's elastic force, thus reducing listener discomfort.
Implementation Method 1
absorbing piezoelectric vibrations through the insulating layer's elastic force
Implementation Method 2
The dielectric layers have piezoelectric and electrostrictive properties. Thus, when a direct current (DC) or alternating current (AC) voltage is applied to an MLCC, a piezoelectric phenomenon may occur between internal electrodes, thereby causing the occurrence of vibrations.
Data Source
AI summary
A multilayer capacitor includes a capacitor body including a plurality of first and second internal electrodes alternately disposed therein and a dielectric layer interposed therebetween, and having first to sixth surfaces, opposing each other, respectively; a plurality of external electrodes connected to the first and second internal electrodes; an insulating layer disposed on the first surface; first and second terminal electrodes spaced apart from each other in a direction in which the third and fourth surfaces are connected, on the insulating layer; and a connecting member electrically connecting the first and second terminal electrodes and the external electrodes.