Multilayer Ceramic Electrode Structure for Solder Stress Relief
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Solution Overview
Problem
Multi-layer ceramic electronic components face cracking issues due to stress caused by solder accumulation during mounting, especially in environments with significant temperature changes, where the ceramic body experiences thermal expansion and contraction, leading to deflection stress that conventional conductive resin external electrodes cannot adequately mitigate.
Innovation Solution
The use of a multi-layer ceramic electronic component design featuring external electrodes with conductive resin layers that cover corners and sides, guiding molten solder to distribute it evenly and reducing stress concentration, thereby preventing cracks. These conductive resin layers have L-shaped configurations on the side and end surfaces to direct solder toward the center, ensuring it covers a wide area and minimizes accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive resin external electrodes are used, then the component structure is simple, but the ceramic body generates cracks due to solder stress concentration
Solution Approach 1:
The external electrode is segmented into multiple functional layers: a base layer covering the end surface, and L-shaped conductive resin layers covering corners and side surfaces. This segmentation allows each layer to perform specific functions in distributing solder stress, preventing crack propagation while maintaining overall structural integrity.
Solution Approach 2:
The conductive resin layers extend from the end surface onto the side surfaces in an L-shaped configuration, adding a dimensional element that guides solder distribution from the end surface outward to the side surfaces. This dimensional extension creates multiple stress distribution pathways, preventing stress concentration at any single location.
2Reliability
If solder accumulates at certain locations during mounting, then the mounting process is simple, but stress concentrates causing ceramic body cracks
Solution Approach 1:
The L-shaped conductive resin layers act as intermediaries between the solder and the ceramic body. These layers receive the solder and guide its distribution across wide areas of the side surfaces, preventing direct stress concentration on the ceramic body while maintaining ease of the soldering process.
Solution Approach 2:
The conductive resin layers change the physical parameters of the external electrode surface by providing extended coverage areas on the side surfaces. This increases the effective solder attachment area and alters the stress distribution pattern, spreading forces over larger areas rather than concentrating them at the end surface.
3Reliability
If the external electrode has high deflection strength, then crack resistance improves, but the electrode structure becomes more complex
Solution Approach 1:
The external electrode uses a composite structure combining a base layer (metal or conductive material) with conductive resin layers. This composite construction provides high deflection strength and crack resistance while maintaining electrical conductivity, achieving enhanced reliability without excessive structural complexity.
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 the generation of cracks in the ceramic body by distributing solder stress evenly, enhancing the reliability and durability of the component under varying temperature conditions.
Implementation Method 1
The first conductive resin layer includes a first side surface resin portion disposed on the first side surface to cover the first corner and extending from the first corner to the direction of the first axis and a direction of the second axis, and covers at least a part of the base layer. This configuration can guide the molten solder at the time of mounting toward the center of the first side surface from the end surface along the inner edge of the first side surface resin portion.
Implementation Method 2
Solder in a molten state wets and spreads upwardly on the external electrode, and then cooled to be solidified. The solder contracts in the process of solidification and gives stress to the ceramic body.
Implementation Method 3
If the circuit board is subjected to a large temperature change, the substrate undergoes thermal expansion and thermal contraction, which may cause deflection stress in the multi-layer ceramic electronic component.
Data Source
AI summary
A multi-layer ceramic electronic component includes: a ceramic body having a substantially rectangular parallelepiped shape, the ceramic body including a first corner connecting a first main surface, a first side surface, and an end surface, a second corner connecting a second main surface, the first side surface, and the end surface, a third corner connecting the first main surface, a second side surface, and the end surface, a fourth corner connecting the second main surface, the second side surface, and the end surface, and a plurality of internal electrodes; and a pair of external electrodes each including a base layer and a first conductive resin layer including a first side surface resin portion disposed on the first side surface to cover the first corner and extending from the first corner to first and second axis directions, and covers at least a part of the base layer.