Coil Component Electrode Structure for Stress-Resistant Adhesion
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Solution Overview
Problem
The downsizing of coil components is hindered by the external electrodes, which generate stress that degrades adhesion between the electrodes and the component body, and reduce the contact area between the electrodes and the component body.
Innovation Solution
A coil component design featuring a magnetic base body with metal magnetic particles bonded by a first resin, a conductor inside or on the base body, and external electrodes with a first conductive resin layer on one surface and a second conductive resin layer on an adjacent surface, both containing different resin content rates and metal particle sizes to manage stress and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the coil component is reduced, then the component body volume must be increased to compensate, but the external electrode thickness must be reduced which decreases contact area and adhesion
Solution Approach 1:
The patent applies different resin content rates to different regions of the conductive paste. The first conductive paste (for the first external electrode) has a resin content rate of 5-20 wt%, while the second conductive paste (for the second external electrode) has a resin content rate of 20-40 wt%. This local variation in material composition allows the first electrode to have strong adhesion while the second electrode can be thinner with reduced stress, resolving the contradiction between electrode thickness and adhesion strength.
Solution Approach 2:
The patent changes the resin content rate parameter of the conductive paste to control the properties of external electrodes. By adjusting the resin content rate from 5-20 wt% to 20-40 wt%, the patent optimizes the balance between adhesion strength and electrode thickness, enabling component downsizing while maintaining sufficient adhesion.
2Strength
If conductive paste with resin is applied to ensure adhesion, then adhesion is improved, but the paste thickness must be increased to compensate for resistance, which increases electrode size
Solution Approach 1:
The patent optimizes the resin content rate parameter to achieve the desired balance between adhesion and thickness. By controlling the resin content rate within specific ranges (5-20 wt% for first paste, 20-40 wt% for second paste), the patent ensures sufficient adhesion while minimizing the thickness required to compensate for resistance, thus reducing overall electrode size.
Data Source
AI summary
A coil component includes a base body, a conductor inside the base body, and an external electrode electrically connected to the conductor. The base body has metal magnetic particles bonded by a first resin, and has a first surface that faces a mounting board, and a second surface adjacent to the first surface. The external electrode includes a first conductive resin layer on the first surface, which is made of a material that contains a second resin and first metal particles. The external electrode includes a second conductive resin layer on the second surface, which is made of a material that contains a third resin and second metal particles. A content rate of the third resin is smaller than a content rate of the second resin. The external electrode includes a metal layer covering the first and second conductive resin layers.