Coil Component Electrode Structure for Adhesion and Low Stress
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Solution Overview
Problem
The downsizing of coil components is hindered by external electrodes, which require adhesion to the component body while maintaining low resistance and reducing stress, and the reduction of contact area between electrodes and the component body leads to decreased adhesion.
Innovation Solution
A coil component with a magnetic base body containing metal magnetic particles bonded by resin, featuring conductive resin layers with varying resin content and metal particle sizes on opposite surfaces, and a metal layer covering these layers to enhance adhesion and reduce stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the external electrode is made thin to reduce component size, then the coil component size is reduced, but the adhesion between the external electrode and component body deteriorates
Solution Approach 1:
The patent uses a composite conductive paste containing resin and metal particles (such as silver or copper) to form the external electrode. This composite structure allows the electrode to maintain adequate adhesion through the resin component while keeping the overall electrode thickness reduced for miniaturization. The metal particles provide conductive pathways through the resin matrix, enabling both mechanical bonding and electrical conductivity in a thin layer.
2Strength
If the conductive paste contains resin to ensure adhesion, then the adhesion between external electrode and component body is improved, but the electrical resistance increases
Solution Approach 1:
The conductive paste is formulated as a composite material where resin and metal particles work synergistically. The resin provides the adhesive bonding to the component body, while the metal particles (such as silver, copper, or their alloys) create conductive networks within the resin matrix. This composite approach allows the external electrode to simultaneously achieve good adhesion and low electrical resistance, resolving the contradiction between mechanical bonding and electrical conductivity.
3Volume of moving object
If the contact area between external electrode and component body is reduced to one or two surfaces, then the coil component size is reduced, but the adhesion between external electrode and component body deteriorates
Solution Approach 1:
The patent applies different conductive paste formulations to different surfaces of the component body. Specifically, the paste applied to the bottom surface (facing the circuit board) has different properties from the paste applied to the side surfaces. This local differentiation allows optimization of adhesion on each surface based on its specific functional requirements, enabling reduced contact area while maintaining adequate adhesion strength through targeted material properties.
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.