Electronic Component External Electrode Stress Distribution

Solution Overview

Problem

Electronic components face issues with crack occurrence and moisture resistance due to external forces and infiltration paths, particularly when solder-mounted on devices, as existing conductive resin layers do not effectively distribute stress and prevent moisture ingress.

Innovation Solution

The electronic component design features a conductive resin layer that continuously covers the mounting surface, end surface, and side surfaces, with a smaller length in the direction of external force application, reducing stress concentration and moisture infiltration paths, and optionally includes a sintered metal layer with a thicker portion on the mounting surface to distribute stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the conductive resin layer covers the entire end surface and principal surfaces, then the coverage area is maximized, but the number of moisture infiltration paths increases and stress concentration occurs

Engineering Contradiction:

Improvecoverage area of conductive resin layerVSAvoidmoisture resistance reliability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The conductive resin layer is selectively applied only to specific regions where stress concentration occurs (corner portions and ridge portions of the element body), rather than covering the entire surface. This localized application reduces the overall coverage area while preventing stress concentration and blocking moisture infiltration paths at critical locations, thereby improving moisture resistance reliability without excessive coverage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The conductive resin layer is divided into multiple discrete regions corresponding to different stress-prone areas of the element body (corner portions and ridge portions). Each segment independently addresses local stress concentration and moisture infiltration risks, achieving effective protection through distributed coverage rather than continuous full-surface coverage

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If the conductive resin layer covers the entire end surface and principal surfaces, then the coverage area is maximized, but stress concentration occurs leading to crack formation

Engineering Contradiction:

Improvecoverage area of conductive resin layerVSAvoidresistance to crack formation

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

The conductive resin layer is selectively applied only to specific regions where stress concentration occurs (corner portions and ridge portions of the element body), rather than covering the entire surface. This localized application reduces the overall coverage area while preventing stress concentration and blocking moisture infiltration paths at critical locations, thereby improving moisture resistance reliability without excessive coverage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The conductive resin layer is divided into multiple discrete regions corresponding to different stress-prone areas of the element body (corner portions and ridge portions). Each segment independently addresses local stress concentration and moisture infiltration risks, achieving effective protection through distributed coverage rather than continuous full-surface coverage

Inventive Principle:

Principle #1Segmentation

3Area of stationary object

If the first length of the conductive resin layer in the first direction is equal to or larger than the second length in the third direction, then the coverage on the mounting surface is maximized, but the number of moisture infiltration paths increases

Engineering Contradiction:

Improvecoverage area on mounting surfaceVSAvoidmoisture infiltration paths

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The conductive resin layer is selectively applied only to specific regions where stress concentration occurs (corner portions and ridge portions of the element body), rather than covering the entire surface. This localized application reduces the overall coverage area while preventing stress concentration and blocking moisture infiltration paths at critical locations, thereby improving moisture resistance reliability without excessive coverage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The conductive resin layer is divided into multiple discrete regions corresponding to different stress-prone areas of the element body (corner portions and ridge portions). Each segment independently addresses local stress concentration and moisture infiltration risks, achieving effective protection through distributed coverage rather than continuous full-surface coverage

Inventive Principle:

Principle #1Segmentation

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 effectively suppresses crack formation and enhances moisture resistance reliability by minimizing stress concentration and infiltration paths, improving the durability and reliability of the electronic component.

Implementation Method 1

The conductive resin layer continuously covers one part of the first principal surface, one part of the end surface, and one part of each of the pair of side surfaces. Therefore, the external force applied onto the electronic component from the electronic device tends not to act on the element body.

Methodology Applied

Scientific EffectStress distribution:

Implementation Method 2

The stress acting on the element body tends to concentrate on the end edge of the sintered metal layer. In a configuration in which the third length is larger than the fourth length, volume of the portion positioned on the first principal surface is large, as compared with an electronic component in which the third length is equal to or smaller than the fourth length. Therefore, this configuration reduces the stress concentrating on the end edge of the sintered metal layer.

Methodology Applied

Scientific EffectStress concentration reduction:

Implementation Method 3

A region between the element body and the conductive resin layer may include a path through which moisture infiltrates. In a case in which moisture infiltrates from the region between the element body and the conductive resin layer, durability of the electronic component decreases. The one aspect includes few paths through which moisture infiltrates, as compared with an electronic component in which the conductive resin layer covers the entire end surface, one part of each of the principal surfaces, and one part of each of the pair of side surfaces.

Methodology Applied

Scientific EffectMoisture infiltration barrier:

Data Source

PatentUS11011310B2Electronic component with external electrode including sintered layer and conductive resin layer on the sintered layer

Publication Date: 2021.05.18 TDK CORP

AI summary

An element body of a rectangular parallelepiped shape includes a first principal surface arranged to constitute a mounting surface, a second principal surface opposing the first principal surface in a first direction, a pair of side surfaces opposing each other in a second direction, and a pair of end surfaces opposing each other in a third direction. An external electrode is disposed on the element body. The external electrode includes a conductive resin layer. The conductive resin layer continuously covers one part of the first principal surface, one part of the end surface, and one part of each of the pair of side surfaces. A length of the conductive resin layer in the first direction is smaller than a length of the conductive resin layer in the third direction.