Multilayer Capacitor Asymmetric Outer Layer for Acoustic Noise Reduction
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Solution Overview
Problem
Multilayer capacitors experience significant acoustic noise due to electrostriction phenomena, which is not adequately reduced by existing techniques, particularly when subjected to alternating-current voltages, causing substrate vibration and noise in electronic devices.
Innovation Solution
A multilayer capacitor design featuring a thicker second outer layer portion and internal conductors in the second outer layer portion, which do not contribute to capacitance, along with a concave or convex portion on the second principle surface, to increase the distance between the capacitance generating portion and the mounting substrate, reducing vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the size of the facing portion of internal electrode is reduced, then acoustic noise is reduced, but capacitance is reduced
Solution Approach 1:
The capacitor body is divided into three distinct portions along the thickness direction: a capacitance generating portion containing internal electrodes, a first outer layer portion, and a second outer layer portion. This segmentation allows the capacitance-generating region to be separated from the noise-transmission path to the substrate, reducing acoustic noise while preserving capacitance in the dedicated generating portion.
Solution Approach 2:
The first and second outer layer portions act as intermediary layers between the capacitance generating portion and the mounting substrate. These outer layer portions serve as buffer zones that interrupt the transmission path of vibration from the capacitance generating portion to the substrate, thereby reducing acoustic noise without affecting the capacitance generation function.
2Object-affected harmful factors
If the distance between capacitance generating portion and mounting substrate is increased, then vibration transmission is reduced, but device height is increased
Solution Approach 1:
The second outer layer portion is designed with a specific thickness that is greater than or equal to that of the first outer layer portion, creating asymmetric local quality in the structure. This localized thickening at the substrate-facing side optimally interrupts vibration transmission to the substrate while minimizing the overall height increase, as the asymmetry is concentrated only where needed for noise reduction.
3Manufacturing precision
If a concave or convex portion is provided on the principle surface, then mounting accuracy is improved, but manufacturing complexity is increased
Solution Approach 1:
A concave or convex portion is provided on one of the principle surfaces of the capacitor body, creating an asymmetric feature that serves as a mechanical stop or positioning element during mounting. This asymmetric structure prevents rotation or misalignment of the capacitor on the substrate, improving mounting accuracy without requiring complex active control systems or additional positioning components.
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 acoustic noise by minimizing vibration transmission to the substrate, maintaining insulation and capacitance properties, and facilitating easy mounting and direction identification.
Implementation Method 1
A multilayer capacitor expands and contracts by the application of voltage due to an electrostriction phenomenon
Data Source
AI summary
A multilayer capacitor that achieves reduced acoustic noise includes a capacitor body including a capacitance generating portion, a first outer layer portion, and a second outer layer portion. First and second internal electrodes are provided in the capacitance generating portion. The first outer layer portion is located between the capacitance generating portion and a first principle surface. The second outer layer portion is located between the capacitance generating portion and a second principle surface. The second outer layer portion is thicker than the first outer layer portion. At least one of a concave portion and a convex portion is provided on the second principle surface.