Multilayer Ceramic Component Asymmetric Cover for Acoustic Noise Reduction
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Solution Overview
Problem
Multilayer ceramic electronic components generate acoustic noise due to piezoelectric vibrations, which are transferred to printed circuit boards through external electrodes and solder, causing discomfort as they produce sound in the audio frequency range of 20 to 20,000 Hz, and existing solutions do not effectively mitigate this noise.
Innovation Solution
A multilayer ceramic electronic component design featuring a ceramic body with alternately exposed internal electrodes, a thicker lower cover part, and external electrodes disposed on end surfaces and the lower surface but not on the upper surface, along with insulating layers to reduce solder height and vibration transfer, is implemented. The external electrodes are formed using a sheet transfer method to ensure uniform thickness and reliability, and the solder is limited to the lower surface to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of dielectric layers is increased and thickness is decreased to achieve miniaturization and high capacitance, then capacitance and size requirements are met, but acoustic noise increases due to piezoelectric vibrations
Solution Approach 1:
The patent applies asymmetry by making the lower cover part thicker than the upper cover part. This asymmetric thickness distribution changes the vibration characteristics of the ceramic body, suppressing piezoelectric vibrations that occur when voltage is applied. The thicker lower cover part acts as a vibration damper, reducing the transmission of vibrations to the printed circuit board and thereby decreasing acoustic noise while maintaining the required high capacitance in a miniaturized structure.
Solution Approach 2:
The patent applies local quality by positioning external electrodes specifically on the lower surface and end surfaces but not on the upper surface. This selective electrode placement creates different electrical field distributions and vibration patterns in different regions of the ceramic body. By avoiding electrodes on the upper surface, the design reduces the areas where vibrations can be generated and transmitted, thereby reducing acoustic noise while still achieving the required capacitance through the stacked multilayer structure.
2Reliability
If external electrodes are disposed on multiple surfaces including upper surface to ensure electrical connection, then electrical reliability is improved, but acoustic noise increases due to vibration transfer through solder
Solution Approach 1:
The patent applies asymmetry in electrode placement by positioning external electrodes on the lower surface and end surfaces but deliberately excluding the upper surface. This asymmetric configuration reduces the number of solder joints and vibration transmission paths to the printed circuit board. The lower surface electrode placement allows electrical connection while the thicker lower cover part suppresses vibrations at the electrode locations, thereby reducing acoustic noise while maintaining electrical reliability.
Solution Approach 2:
The patent applies the extraction principle by removing external electrodes from the upper surface of the ceramic body. This elimination of electrodes from the upper surface reduces the areas where vibrations can be generated and transmitted through solder to the printed circuit board. The necessary electrical connections are maintained through electrodes on the lower surface and end surfaces, achieving the required reliability with reduced acoustic noise.
3Reliability
If uniform thickness external electrodes are used for reliability, then electrical connection is improved, but acoustic noise transmission through solder is increased
Solution Approach 1:
The patent applies asymmetry by positioning external electrodes on the lower surface and end surfaces but not on the upper surface. This asymmetric electrode distribution, combined with the thicker lower cover part, creates a configuration where solder connections are made at locations with reduced vibration amplitude. The uniform thickness of external electrodes ensures reliable electrical connection, while their strategic asymmetric placement minimizes vibration transmission to the printed circuit board, thereby reducing acoustic noise.
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
This design significantly reduces acoustic noise to less than 25 dB by controlling the deformation and vibration transfer, maintaining high capacitance and reliability, and avoiding the need for distinguishing marks or colors on the ceramic body surfaces.
Implementation Method 1
Since the dielectric layers have a piezoelectric property and an electrostrictive property, a piezoelectric phenomenon occurs between the internal electrodes when direct current (DC) or alternating current (AC) voltages are applied to the multilayer ceramic electronic component, which may cause vibrations.
Implementation Method 2
Since the dielectric layers have a piezoelectric property and an electrostrictive property, a piezoelectric phenomenon occurs between the internal electrodes when direct current (DC) or alternating current (AC) voltages are applied to the multilayer ceramic electronic component, which may cause vibrations.
Data Source
AI summary
A multilayer ceramic electronic component includes: a ceramic body including: an active part with dielectric layers interposed with a plurality of first and second internal electrodes; an upper cover part above the active part; a lower cover part below the active part and having a thickness greater than that of the upper cover part; and first and second external electrodes electrically connected to the first and second internal electrodes, respectively, wherein the first and second external electrodes are disposed on respective end surfaces of the ceramic body in a length direction and on a lower surface of the ceramic body in a thickness direction and are not disposed on an upper surface of the ceramic body in the thickness direction.