Ceramic Electrode Structure for Plating and Joint Reliability
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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 frit content 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 and a second region with high-melting-point oxides, optimizing the composition and area ratios to enhance joint strength and prevent plating defects.
Engineering Contradictions & Design Principles
Engineering 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
Solution Approach 1:
The baked electrode is divided into a first region containing glass frits for strong bonding to the element body, and a second region containing high-melting-point oxides for good plating properties. This local differentiation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The baked electrode is segmented into distinct functional regions: a first region with glass frits (B, Zn, Si) for joint strength, and a second region with high-melting-point oxides for plating quality. This segmentation resolves the contradiction by spatially separating the competing requirements.
2Strength
If glass frits are contained in the baked electrode, then the joint strength is improved, but plating defects occur due to glass frit exposure
Solution Approach 1:
Glass frits are localized to the first region where they provide bonding strength, while the second region contains only high-melting-point oxides to prevent plating defects. This spatial separation eliminates the harmful effect of glass frit exposure while preserving the beneficial bonding effect.
Solution Approach 2:
The harmful glass frit components are extracted from the second region (outer surface area) and confined to the first region. This extraction eliminates plating defects on the outer surface while maintaining joint strength through glass frits in the bonding region.
3Ease of manufacture
If the baked electrode is formed with conventional composition, then the manufacturing process is simple, but the external electrode may peel off under thermal shock
Solution Approach 1:
The baked electrode uses a composite material structure with two distinct compositions: glass frits (B, Zn, Si) in the first region for bonding, and high-melting-point oxides in the second region for thermal stability. This composite approach enhances joint reliability under thermal shock while remaining manufacturable.
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 improves both plating properties and joint reliability, preventing peeling and ensuring robust bonding even under thermal shock, by strategically using glass frits and high-melting-point oxides in specific regions of the baked electrode layer.
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 of the baked electrode layer to the element body
Implementation Method 2
Since a predetermined high-melting-point oxide is present near the outer surface, it is considered to be able to prevent the deposition of non-metal components, such as glass frits, on the outer surface of the baked electrode layer
Data Source
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, Zn, and Si. The second region includes an oxide having a higher melting point than Cu.