Multilayer Ceramic Capacitor Wall Structure for Acoustic Noise
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Solution Overview
Problem
Multilayer ceramic capacitors generate 'acoustic noise' due to piezoelectric and electrostrictive properties of dielectric layers, which cause stress and mechanical strain when an electric field is applied, leading to vibration transmission to the substrate through solder.
Innovation Solution
The multilayer ceramic capacitor design includes a multilayer body with external electrodes and wall portions that protrude from the main surface, covering the external electrodes and acting as a buffer to absorb vibrations, reducing the transmission of stress and mechanical strain to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder extends to the position of internal electrode layer, then electrical connection is improved, but acoustic noise generation increases
Solution Approach 1:
The patent introduces a resin layer as an intermediary substance between the solder and the internal electrode layer. This resin layer acts as a buffer that absorbs mechanical vibrations while maintaining electrical connection, thereby preventing acoustic noise generation without compromising reliability
Solution Approach 2:
The patent applies a resin coating beforehand on the external electrode before soldering. This pre-applied cushioning layer is designed to absorb vibrations during operation, preventing the transmission of mechanical stress to the internal electrode layer and thus preventing acoustic noise before it can occur
2Reliability
If dielectric layers have piezoelectric properties, then capacitance function is improved, but vibration transmission to substrate increases
Solution Approach 1:
The resin layer serves as a mediator between the piezoelectric dielectric layers and the substrate. It absorbs the vibrations generated by the piezoelectric effect while allowing the capacitance function to operate normally, thus decoupling the useful function from the harmful vibration transmission
Solution Approach 2:
The patent changes the physical parameters of the interface between the capacitor and substrate by introducing a resin layer with specific mechanical properties. This modifies the vibration transmission characteristics while preserving the electrical capacitance function of the dielectric layers
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 effectively reduces or prevents the generation of 'acoustic noise' by absorbing piezoelectric vibrations and preventing the transmission of stress and mechanical strain to the substrate, enhancing the stability and noise reduction of the multilayer ceramic capacitors.
Implementation Method 1
since the dielectric layers have piezoelectric and electrostrictive properties, stress and mechanical strain occur when an electric field is applied. Such stress and mechanical strain cause vibration
Implementation Method 2
since the dielectric layers have piezoelectric and electrostrictive properties, stress and mechanical strain occur when an electric field is applied
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body, two external electrodes, and two wall portions. The multilayer body includes a multilayer main body including an inner layer portion in which dielectric layers and internal electrode layers are stacked, and two outer layer portions on opposite sides of the inner layer portion in a stacking direction, two side gap portions on opposite sides of the multilayer main body in a width direction, two main surfaces on opposite sides in the stacking direction, two side surfaces on opposite sides in the width direction, and two end surfaces on opposite sides in a length direction. The two external electrodes each are provided at one of the two end surfaces of the multilayer body, and each extend from the one of the two end surfaces to a portion of the main surface. The wall portions cover portions of the external electrodes at the two end surfaces, and each include a protruding portion that protrudes from the main surface.