Multi-Layer Ceramic Capacitor Terminal Structure for Reflow Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-voltage multi-layer ceramic capacitors face issues with creeping discharge and boundary separation between the ceramic body and external material during reflow soldering, leading to potential defects due to stress concentration at the external electrode tips.
Innovation Solution
A multi-layer ceramic electronic component design featuring a gap between the external electrodes and the ceramic body, covered with an external material, which reduces stress concentration and prevents separation by distributing stress vertically, thereby stabilizing the connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external electrode tip is in direct contact with the multi-layer body, then the electrical connection is good, but stress concentration occurs during reflow soldering causing boundary separation between the multi-layer body and external material
Solution Approach 1:
The patent introduces an external electrode as an intermediary element between the multi-layer body and the solder joint. This external electrode absorbs and distributes the thermal expansion stress, preventing direct stress transmission to the boundary between the multi-layer body and external material, thereby preventing boundary separation while maintaining electrical connection
Solution Approach 2:
The patent changes the physical state of the bonding material from solid to liquid during reflow soldering, allowing it to flow and fill gaps. This parameter change enables the bonding material to adapt to thermal expansion differences and reduce stress concentration at the external electrode tip, preventing boundary separation
2Reliability
If the bonding material is melted during reflow soldering, then the electrical connection is established, but stress is generated causing separation between the multi-layer body and external material
Solution Approach 1:
The patent utilizes the phase transition of the bonding material from solid to liquid during reflow soldering. This phase transition allows the bonding material to flow and fill gaps, establishing reliable electrical connection. After cooling, the bonding material solidifies, providing strong mechanical strength to prevent separation between the multi-layer body and external material
Solution Approach 2:
The patent designs the external electrode structure with sufficient length and appropriate geometry before soldering. This beforehand cushioning design ensures that the external electrode can absorb thermal expansion stress during the soldering process, preventing stress from reaching the boundary between the multi-layer body and external material, thereby maintaining both electrical connection and mechanical strength
3Stress or pressure
If the external electrode is long enough to prevent separation, then the stress distribution is improved, but the electrical connection reliability may be compromised
Solution Approach 1:
The patent applies different properties to different parts of the external electrode. The portion near the multi-layer body has optimized dimensions and material properties for stress distribution, while the terminal portion is designed for optimal electrical connection. This local quality differentiation allows the external electrode to simultaneously achieve good stress distribution and reliable electrical connection
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 design effectively prevents separation and creeping discharge, ensuring reliable mounting and reducing the risk of product defects by balancing stress distribution during reflow soldering.
Implementation Method 1
the external material is positioned in the gap... reduces stress concentration and prevents separation by distributing stress vertically
Data Source
AI summary
A multi-layer ceramic electronic component includes a multi-layer ceramic electronic component main body including a multi-layer body including stacked ceramic layers, stacked internal electrode layers, first and second main surfaces, first and second side surfaces, and first and second end surfaces, first and second external electrodes respectively on sides where the first and second end surfaces are located, and first and second metallic terminals respectively connected to the first and second external electrodes. The multi-layer ceramic electronic component main body and at least portion of the first and second metallic terminals are covered with an external material. The second main surface is connected to the metallic terminals. The first and second external electrodes cover a portion of the second main surface. A gap is provided between the multi-layer body and tips of the first and second external electrodes. The external material is in the gap.