Multilayer Capacitor External Electrode Stress Distribution
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Solution Overview
Problem
Multilayer capacitors face challenges in achieving high flexural strength, which is essential for miniaturized and high-integration electronic components, particularly in automotive and infotainment systems, where they are subjected to mechanical stress and reduced spacing.
Innovation Solution
A multilayer capacitor design featuring a capacitor body with a laminated dielectric and internal electrodes, an external conductive electrode with a conductive resin layer, and a plating layer, where the conductive resin layer's inner and outer band portions are strategically extended to enhance bending strength by distributing stress and preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the multilayer capacitor is miniaturized to meet high integration requirements, then the space occupied is reduced, but the flexural strength and resistance to mechanical stress deteriorate
Solution Approach 1:
The external electrode is segmented into multiple functional portions: inner connecting portion, inner band portion, outer connecting portion, and outer band portion. This segmentation allows each portion to perform specific functions - the inner portions provide electrical connection while the outer portions extend beyond the capacitor body to provide mechanical reinforcement and stress distribution, thereby improving flexural strength without increasing the overall capacitor volume.
Solution Approach 2:
The external electrode uses a composite structure combining conductive materials (for electrical connection) with conductive resin materials (for mechanical strength). The conductive resin layer provides flexibility and mechanical reinforcement, while the conductive layer ensures electrical conductivity. This composite approach enables the miniaturized capacitor to maintain high flexural strength despite reduced dimensions.
2Productivity
If the spaces between mounted multilayer capacitors are reduced for high integration, then the integration density increases, but the reliability under mechanical stress decreases
Solution Approach 1:
The outer band portions of the external electrode are designed to extend beyond the capacitor body boundaries in advance, creating a mechanical reinforcement structure before the capacitor is mounted. This preliminary extension of the conductive resin layer provides pre-existing stress distribution capability, preventing crack propagation during subsequent mounting and operation, thereby ensuring reliability even in high-density integrated configurations.
3Strength
If the conductive resin layer is extended to improve bending strength, then the flexural strength increases, but the device complexity increases
Solution Approach 1:
The conductive resin layer is designed to perform multiple functions simultaneously: it provides mechanical reinforcement for bending strength, ensures electrical conductivity through the resin's conductive properties, and facilitates stress distribution across the electrode structure. By making the conductive resin layer multi-functional, the patent avoids adding separate components for each function, thereby improving bending strength without proportionally increasing device complexity.
Data Source
AI summary
A multilayer capacitor includes a capacitor body including a multilayer structure of a dielectric layer and a plurality of internal electrodes; and an external electrode including a conductive layer and a conductive resin layer covering the conductive layer. The conductive layer includes an inner connecting portion disposed on a surface of the capacitor body and connected to the internal electrodes, and an inner band portion extending from the inner connecting portion to a portion of a mounting surface of the capacitor body. The conductive resin layer includes an outer connecting portion disposed on the inner connecting portion, and an outer band portion extending from the outer connecting portion to a portion of the mounting surface and covering the inner band portion. A ratio of a length of the inner band portion to a length of the outer band portion is 0.3 to 0.7.