Multilayer Ceramic Component Edge Electrode Stress Control
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Solution Overview
Problem
Existing multilayer ceramic capacitors face challenges in reducing residual stress caused by external electrodes, which affects their mechanical strength and reliability.
Innovation Solution
A multilayer ceramic electronic component design featuring external electrodes with a specific composition and structure, including a metal (Cu) and inorganic (Si) components, and voids, extending around the edge of the ceramic body with a controlled occupancy area ratio of 25-75% and thickness of 5-10 μm, to reduce residual stress and enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external electrodes are formed with conventional conductive paste containing glass frit, then the external electrodes can be formed on end surfaces, but residual stress accumulates at the edge regions where electrodes extend onto side surfaces, reducing mechanical strength
Solution Approach 1:
The patent applies different occupancy area ratios at different locations of the external electrode. The edge region (within 50 μm of the leading edge) has an occupancy area ratio of 25-75%, while other regions have different ratios. This local variation in composition reduces residual stress at the critical edge region where stress concentration occurs, thereby improving mechanical strength while maintaining reliable electrode formation
Solution Approach 2:
The patent changes the chemical composition parameters of the conductive paste by controlling the occupancy area ratio of metal particles to inorganic particles. By adjusting this ratio to 25-75% in the edge region, the physical and mechanical properties of the external electrode are modified to reduce residual stress and improve overall mechanical strength
2Reliability
If the external electrode extends around from the end surface to the side surface, then electrical connection is improved, but residual stress increases at the edge region, leading to potential cracks
Solution Approach 1:
The patent implements local quality control by varying the occupancy area ratio at the edge region compared to other regions. The edge region within 50 μm of the leading edge has an occupancy area ratio of 25-75%, which specifically addresses the stress concentration problem at this location while maintaining the extending-around structure for electrical connection
3Strength
If glass frit composition is controlled to adjust coefficient of linear expansion, then bending strength is improved, but residual stress cannot be sufficiently reduced
Solution Approach 1:
The patent changes the composition parameters of the conductive paste by controlling the occupancy area ratio of metal to inorganic particles to 25-75% in the edge region. This parameter adjustment reduces residual stress more effectively than merely controlling glass frit composition, thereby improving mounting reliability while maintaining bending strength
Data Source
AI summary
A multilayer ceramic electronic component includes a ceramic body having an end surface and a side surface adjacent to thereto such that the end surface and the side surface meet at an edge. The ceramic body has a plurality of internal electrodes with adjacent pairs of the internal electrodes being separated by a respective ceramic layer. An external electrode containing a metal, an inorganic component and voids is electrically connected to at least some of the internal electrodes and both covers the end surface and extends over the edge onto the side surface to form an extending-around portion which extends at least 50 μm onto the side surface as measured in a direction perpendicular to the edge and ends at a leading edge remote from the edge. A portion of the extending-around area which extends 50 μm from the leading edge towards the edge has an average occupancy area ratio which is at least 25 but not greater than 75. The occupancy area ratio is the ratio between the area of the conductive component and an area of the inorganic component on the one hand to the area of the conductive component, the area of the inorganic component and the area of the voids on the other.