Coil Component Rounded Flange Reduces Wire Stress
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Solution Overview
Problem
The existing wire-wound coil components face issues with wire breakage due to stress concentration at the intersection of the mounting surface and inner end surface of the flange portion during thermocompression bonding, especially when the wire diameter reduces or the coil component is exposed to high temperatures, leading to instability in the bonding process.
Innovation Solution
The coil component design features a rounded surface on the mounting surface and a recess with a flat surface, allowing the wire to extend along the rounded surface and be received in the recess, with a thickness that gradually changes from thin to thick, reducing stress concentration and improving bonding stability by controlling pressure distribution during thermocompression bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermocompression bonding is performed at high temperature and high pressure to achieve stable bonding, then bonding strength is improved, but wire breakage occurs due to stress concentration
Solution Approach 1:
The patent applies a curvature principle by forming a rounded surface (specifically a spherical surface) at the corner portion of the flange where stress concentration occurs. This curved geometry redistributes the stress during thermocompression bonding, preventing stress concentration at sharp corners while maintaining effective bonding pressure on the wire. The spherical surface has a predetermined radius of curvature that optimizes stress distribution, allowing high-temperature bonding without wire breakage.
Solution Approach 2:
The patent applies local quality by modifying only the specific corner portion of the flange where stress concentration occurs, rather than changing the entire flange structure. The rounded surface is formed selectively at the intersection of the mounting surface and inner end surface, creating a localized stress-distributing feature that preserves the overall bonding process effectiveness while preventing wire breakage at the critical stress point.
2Volume of moving object
If wire diameter is reduced to decrease component size, then miniaturization is achieved, but wire becomes more susceptible to breakage during bonding
Solution Approach 1:
The rounded surface with predetermined curvature radius provides a gradual transition zone that reduces stress concentration on thinner wires. The curved geometry distributes bonding pressure more evenly across the wire cross-section, preventing stress peaks that would cause breakage in miniaturized components with finer wires.
Solution Approach 2:
The rounded surface acts as a pre-designed stress-distributing feature that cushions the wire against excessive bonding pressure before the actual bonding occurs. This preventive geometric feature is built into the flange structure in advance, protecting vulnerable thin wires from breakage during the high-pressure bonding process.
3Stability of the object's composition
If high pressure is applied during thermocompression bonding to ensure proper bonding, then bonding stability is improved, but stress concentration at the ridge line causes wire breakage
Solution Approach 1:
The spherical surface replaces the sharp ridge line geometry with a curved surface that has a predetermined radius of curvature. This geometric modification allows high bonding pressure to be applied stably while the curved surface distributes the stress, preventing concentration at the original ridge line location and avoiding wire breakage.
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 prevents wire breakage and ensures stable thermocompression bonding by distributing pressure more evenly, maintaining the wire's strength and adhesion to the terminal electrode, thereby enhancing the reliability of the coil component.
Implementation Method 1
The insulating film made of the resin is decomposed by, for example, heat, which is applied when thermocompression bonding is performed, and removed.
Implementation Method 2
apply heat at a relatively high temperature, which is, for example, about 300° C. to about 500° C., and a relatively high pressure to the wire 6 so as to cause moderate plastic deformation of the wire 6
Data Source
AI summary
Terminal electrodes are disposed on mounting surfaces of flanges of a substantially drum-shaped core that are directed to a mounting substrate. A rounded surface is formed on the mounting surface. An end portion of the wire extends along the rounded surface from a side on which the inner end surface is present toward a side on which the outer end surface is present.