MLCC Bonding Layer Structure for Crack-Free External Electrodes
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Solution Overview
Problem
The development of ultra-small multilayer ceramic capacitors (MLCCs) faces challenges with radial cracks and non-uniform external electrode thickness due to the dipping method, which affects the strength and reliability of the ceramic body, and the dependency on temperature for capacitance implementation.
Innovation Solution
A ceramic electronic component design featuring a bonding layer between the ceramic body and the external electrode, where the external electrode is separately manufactured and thermally bonded, reducing the heat treatment temperature and ensuring uniform thickness, thereby minimizing radial cracks and binder-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external electrode is formed by dipping method and baked at high temperature, then the external electrode can be attached to the ceramic body, but radial cracks occur due to strain concentration at triple points
Solution Approach 1:
A bonding layer is introduced as an intermediary between the external electrode and the ceramic body. This bonding layer acts as a strain-absorbing interface that prevents stress concentration at triple points during the reduction process, thereby eliminating radial cracks while allowing the external electrode to be properly attached to the ceramic body.
Solution Approach 2:
The external electrode is separately manufactured and pre-baked before being attached to the ceramic body. This preliminary action ensures the external electrode achieves its final shape and density before bonding, reducing the need for high-temperature processing after assembly and minimizing thermal stress on the ceramic body.
2Manufacturing precision
If the external electrode is formed by dipping method, then the external electrode can be applied to the ceramic body, but the edge portion has reduced thickness due to three-dimensional reduction
Solution Approach 1:
The manufacturing process is segmented into separate steps: the external electrode is manufactured independently as a separate component with controlled thickness, then attached to the ceramic body via a bonding layer. This segmentation allows precise control of external electrode thickness without the distortion issues inherent in the dipping method, achieving uniform thickness while maintaining manufacturing feasibility.
3Reliability
If the external electrode includes glass and copper with high glass content, then the external electrode can be thermally bonded, but the capacitance becomes highly temperature-dependent
Solution Approach 1:
The glass content is distributed non-uniformly within the external electrode: a first region near the bonding interface contains high glass content for strong thermal bonding, while a second region toward the external surface contains low glass content for stable capacitance. This local quality differentiation allows the external electrode to achieve both strong bonding and temperature-independent capacitance performance.
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 approach reduces the risk of radial cracks, achieves uniform external electrode thickness, and decreases the temperature dependency for capacitance implementation, enhancing the reliability and performance of the MLCCs.
Implementation Method 1
a bonding layer disposed between the body and the external electrode... thermally bonded to a ceramic body using the bonding layer
Data Source
AI summary
A ceramic electronic component includes a body including a dielectric layer and an internal electrode; an external electrode disposed on the body; and a bonding layer disposed between the body and the external electrode. The bonding layer has a thickness less than a thickness of the external electrode.