Coil Component Electrode Layout for Low-Resistance Mounting
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Solution Overview
Problem
Two-terminal type coil components with a single coil conductor embedded in an element body experience increased connection resistance when mounted on a circuit board due to the use of conductive resin in a five-surface electrode structure.
Innovation Solution
A coil component design featuring an element body with specific side surfaces and conductive resin layers that expose and connect bump conductors and dummy bump conductors to reduce connection resistance, while maintaining mounting characteristics similar to a four-terminal type coil component, using conductive resin layers strategically to enhance stress relaxation and wettability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a five-surface electrode structure with conductive resin is used, then the coil component can be mounted on a circuit board, but the connection resistance increases
Solution Approach 1:
The patent applies local quality by making different parts of the electrode structure have different properties: the mounting surface has conductive resin for stress relaxation and wettability, while the side surfaces have exposed bump conductors for low resistance connections. This resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The electrode structure is segmented into multiple functional parts: bump conductors for electrical connection, dummy bump conductors for mechanical support, and conductive resin layers for stress relaxation. This segmentation allows each part to optimize its function, reducing overall connection resistance while maintaining mounting reliability.
2Reliability
If conductive resin is used to connect bump conductors, then stress relaxation is enhanced, but connection resistance increases
Solution Approach 1:
The conductive resin acts as an intermediary material that connects the bump conductors to the circuit board while providing stress relaxation. The resin layer absorbs mechanical stress and improves wettability, while the exposed side surface portions of the bump conductors provide direct low-resistance electrical pathways, thus resolving the contradiction between stress relaxation and connection resistance.
3Reliability
If all side surfaces are covered with conductive resin, then wettability is improved, but connection resistance increases
Solution Approach 1:
The patent applies local quality by selectively covering only the mounting surface with conductive resin while leaving the side surfaces exposed. The mounting surface benefits from improved wettability and stress relaxation, while the side surfaces provide direct electrical connections with low resistance, thus resolving the contradiction.
Data Source
AI summary
Disclosed herein is a coil component that includes a coil conductor embedded in the element body; a first bump conductor exposed to the mounting surface and the first and side surfaces; a second bump conductor exposed to the mounting surface and the second and fourth side surfaces; a first dummy bump conductor exposed to the mounting surface and the first and fourth side surfaces; a second dummy bump conductor exposed to the mounting surface and the second and third side surfaces; a first conductive resin layer connecting the first bump conductor and first dummy bump conductor; and a second conductive resin layer connecting the second bump conductor and the second dummy bump conductor. The first and bump conductors and the first and second dummy bump conductors are not covered at least partly with the first conductive resin layer.