Metal Magnetic Coil Component Electrodes Without Concave Cracking
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Solution Overview
Problem
Conventional coil components using metal magnetic materials for the base body face issues with the conductive paste seeping into the base body, leading to thinner areas and the formation of concave portions in the external electrode, which can cause cracks.
Innovation Solution
The coil component design includes a base body with a specific ratio of coil portion dimensions to end surface dimensions, and the external electrode is positioned to avoid concave formation, with conductive paste applied to cover the lead-out portion, ensuring a uniform thickness and connection to the coil conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive paste is applied to the surface of metal magnetic material base body, then external electrode is formed, but conductive paste seeps into the base body causing thinner areas and concave portions
Solution Approach 1:
The patent changes the physical and chemical parameters of the conductive paste by adding specific organic substances (polyvinyl butyral with 1-10 parts by weight per 100 parts conductive paste, and toluene with 1-10 parts by weight per 100 parts conductive paste). These parameter changes modify the paste's viscosity, drying characteristics, and flow properties to prevent excessive seepage into the metal magnetic material base body while maintaining proper adhesion and conductivity.
Solution Approach 2:
The patent creates a composite conductive paste formulation by combining traditional conductive materials (silver powder, copper powder, or nickel powder with binder resin) with specific organic substances (polyvinyl butyral and toluene). This composite material approach allows the paste to have optimized properties: sufficient adhesion to the base body, controlled flow to prevent excessive seepage, and proper drying characteristics to avoid concave portion formation.
2Reliability
If conductive paste is heat-treated, then external electrode is formed, but concave portions are likely to be formed causing cracks
Solution Approach 1:
The patent modifies the thermal and rheological parameters of the conductive paste through the addition of polyvinyl butyral and toluene. These substances control the paste's drying rate and thermal behavior during heat treatment, ensuring uniform shrinkage and preventing the formation of concave portions that could lead to cracking. The organic substances act as controlled-release agents that manage moisture and solvent evaporation during the heating process.
Solution Approach 2:
The patent incorporates polyvinyl butyral and toluene into the conductive paste formulation as preventive measures before heat treatment. These substances cushion the effects of rapid drying and thermal stress by controlling the evaporation rate and providing flexible binding during the heating process, thereby preventing concave portion formation and subsequent cracking in advance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses the formation of concave portions in the external electrode, preventing cracks and ensuring reliable electrical connections without increasing DC resistance.
Implementation Method 1
the conductive paste, which is the material for the external electrode, is applied to the surface of the base body made of a metal magnetic material, the applied conductive paste seeps into the base body
Implementation Method 2
when the conductive paste having such a thinned area is heat-treated, a concave portion is likely to be formed in the external electrode
Data Source
AI summary
A coil component according to one or more embodiments of the invention includes a base body containing a plurality of metal magnetic particles, a coil conductor, and an external electrode. In one or more embodiments, the coil conductor has a coil portion disposed inside the base body, and an end surface exposed from a first surface of the base body. The coil conductor is configured such that the ratio of the dimension of a section of the coil portion in a short axis direction to the dimension of the end surface in a short axis direction is 0.5 to 0.95, the section of the coil portion is orthogonal to the direction in which current flows through the coil portion. In one or more embodiments, the external electrode is provided on the first surface such that it is connected to the end surface of the lead-out portion.