Monolithic Capacitor Mounting Structure for Vibration Noise Reduction

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Solution Overview

Problem

Monolithic capacitors generate vibration noise due to piezoelectric or electrostrictive effects, which are not adequately reduced by existing mounting techniques, especially when using high dielectric constant ceramics, as they vibrate not only in the direction of thickness but also in the planar direction of inner electrodes.

Innovation Solution

A monolithic capacitor mounting structure is designed with specific shapes and positions of outer electrodes and bonding portions on a mounting substrate, where the length of bonding portions is between 0.2 to 0.5 times the length of the capacitor and centered differently from the capacitor's center, minimizing regions of volume change, thereby reducing vibration noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the monolithic capacitor is mounted with inner electrode surfaces oriented perpendicularly to the substrate surface, then vibration in the thickness direction is reduced, but vibration in the planar direction of inner electrodes is not reduced

Engineering Contradiction:

Improvevibration noiseVSAvoidmounting orientation flexibility

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent applies asymmetry by positioning the bonding portions asymmetrically with respect to the center of the monolithic capacitor in the lengthwise direction. The bonding portions are located at positions where the absolute value of the second-order partial derivative of volume change is minimized, which are not at the center position. This asymmetric positioning effectively reduces vibration noise in the planar direction while maintaining electrical functionality.

Inventive Principle:

Principle #4Asymmetry

2Quantity of substance

If high dielectric constant ceramics are used to increase capacitance, then the capacitance value is improved, but vibration noise is increased

Engineering Contradiction:

ImprovecapacitanceVSAvoidvibration noise

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful vibration effect into a beneficial outcome by strategically positioning the bonding portions at locations where volume change due to piezoelectric or electrostrictive effects is minimized. By using high dielectric constant ceramics that exhibit strong piezoelectric or electrostrictive effects and positioning the bonding portions where the second-order partial derivative of volume change is minimal, the patent reduces vibration noise transmission to the substrate while maintaining high capacitance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If the bonding portions are positioned at the center of the elementary body, then manufacturing is simplified, but vibration noise is not reduced

Engineering Contradiction:

Improvebonding alignmentVSAvoidvibration noise

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by identifying and utilizing specific regions within the monolithic capacitor where volume change is minimized. The bonding portions are positioned at locations where the absolute value of the second-order partial derivative of volume change with respect to the applied voltage is minimized, rather than uniformly at the center. This localized positioning strategy reduces vibration noise while maintaining ease of manufacturing through clear positional guidelines.

Inventive Principle:

Principle #3Local quality

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 configuration significantly reduces or prevents vibration noise by mounting the capacitor in regions with minimal distortion, effectively addressing the multi-directional vibration issue of monolithic capacitors.

Implementation Method 1

When an AC voltage or a DC voltage superimposed with an AC voltage is applied to the monolithic capacitor, vibration is generated with mechanical distortion due to the piezoelectric or electrostrictive effect

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

Methodology Applied

Scientific EffectElectrostrictive effect: Electrostriction

Data Source

PatentUS9374901B2Monolithic capacitor mounting structure and monolithic capacitor

Publication Date: 2016.06.21 MURATA MFG CO LTD

AI summary

In a monolithic capacitor mounting structure, assuming that a portion of a first outer electrode joined with a first bonding material is a first bonding portion and a portion of a second outer electrode joined with a second bonding material is a second bonding portion, a length of each of the first and second bonding portions in a lengthwise direction of the monolithic capacitor is about 0.2 times to about 0.5 times a length of an elementary body in the lengthwise direction, and a center of each of the first and second bonding portions in the lengthwise direction is located at a position different from a center of the elementary body in the lengthwise direction. Vibration noise is changed depending on positions of outer electrodes of the monolithic capacitor, the outer electrodes being used to bond the monolithic capacitor to a mounting substrate.