Ceramic Electrode Structure Balancing Plating and Joint Strength

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Solution Overview

Problem

Existing ceramic electronic devices face challenges in achieving both favorable plating properties and high joint reliability for external electrodes, as reducing glass frits in baked electrodes improves plating but compromises joint strength, leading to potential peeling issues.

Innovation Solution

A ceramic electronic device design featuring a baked electrode layer with a first region containing glass frits for improved joint strength and a second region with Al-based oxides to prevent plating defects, where the Al-based oxides have a higher melting point than Cu and are non-vitrified, enhancing both plating properties and joint reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amount of glass frits in the baked electrode is reduced, then the plating property is improved, but the joint strength to the element body decreases

Engineering Contradiction:

Improveplating propertyVSAvoidjoint strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The baked electrode is divided into two regions with different compositions: the first region (near the joint boundary) contains glass frit as the main component to ensure strong joint strength, while the second region (outer surface) contains Al-based oxide to provide favorable plating properties. This local differentiation allows each region to optimize its function without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The baked electrode uses a composite structure combining glass frit and Al-based oxide in different regions. The glass frit provides adhesion and joint strength at the interface with the element body, while the Al-based oxide provides a suitable surface for plating. This composite approach resolves the contradiction by combining materials with complementary properties in appropriate locations.

Inventive Principle:

Principle #40Composite materials

2Strength

If glass frits are contained in the baked electrode to improve joint strength, then plating defects occur due to exposed glass frits on the outer surface

Engineering Contradiction:

Improvejoint strengthVSAvoidplating property

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The harmful component (glass frit) is extracted from the outer surface region where it causes plating defects, and concentrated in the first region near the joint boundary where it provides necessary adhesion. This extraction eliminates the harmful effect while preserving the beneficial function.

Inventive Principle:

Principle #2Taking out (Extraction)

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

The proposed design effectively prevents plating defects and ensures the external electrode does not peel from the element body, even under thermal shock, by maintaining strong joint reliability and favorable solder wettability.

Implementation Method 1

The glass frit is considered to spread wet in the conductor and between the conductor and the end surface of the element body and improve the joint strength

Methodology Applied

Scientific EffectWetting: Wetting

Implementation Method 2

Since an oxide including Al is present near the outer surface, it is considered to be able to prevent the vitrification and deposition of non-metal components on the outer surface of the baked electrode layer

Methodology Applied

Scientific EffectVitrification prevention: Vitrification

Data Source

PatentUS11984266B2Ceramic electronic device

Publication Date: 2024.05.14 TDK CORP

AI summary

A ceramic electronic device includes an element body and an external electrode. The element body includes a ceramic layer and an internal electrode layer. The external electrode is formed on an end surface of the element body and electrically connected to a part of the internal electrode layer. The ceramic layer includes a perovskite compound represented by ABO3 as a main component. The external electrode includes a baked electrode layer having a first region and a second region. The first region is contacted with the end surface of the element body and located near a joint boundary with the element body. The second region is located outside the first region and constitutes an outer surface of the baked electrode layer. The first region includes a glass frit including at least B and Si. The second region includes an Al based oxide mainly including Al.