Multilayer Inductor Winding Layout to Reduce Resin Cracking
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Solution Overview
Problem
The existing inductor components with resin coating members are prone to cracking due to significant stress loads from resin expansion and contraction, and uneven thickness caused by winding return portions covering the winding core top surface.
Innovation Solution
The inductor component design includes winding return portions positioned to cover the outer peripheral surface excluding the winding core top surface, with multilayer winding portions distributed along the axial direction, ensuring adjacent turns of the wire form contact or gaps no larger than the wire radius, reducing resin volume and thickness unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resin coating member is made thick to fill large gaps between wire turns, then the gaps are filled and magnetic path is improved, but the stress load from resin expansion and contraction increases significantly
Solution Approach 1:
The patent applies local quality by making the resin coating member thin only in regions where wire turns are closely spaced (small gaps), rather than uniformly thick throughout. This localized thinning reduces resin volume and stress concentration in critical areas while maintaining adequate coating thickness where gaps are larger, thus balancing magnetic path continuity with stress reduction.
Solution Approach 2:
The patent changes the thickness parameter of the resin coating member from a constant value to a variable value that depends on the local gap size between wire turns. By adjusting the thickness parameter locally based on gap measurements, the design optimizes both magnetic path continuity (adequate thickness where needed) and stress reduction (thin thickness where gaps are small).
2Reliability
If the resin coating member thickness increases to cover winding return portions, then complete coverage is achieved, but thickness unevenness increases causing stress concentration
Solution Approach 1:
The patent applies local quality by varying the resin coating thickness according to the local topography of the wound wire. In regions with winding return portions where coverage is critical, the coating is made thicker. In regions where wire turns are closely spaced, the coating is made thinner. This spatially varying thickness achieves complete coverage while minimizing thickness unevenness and associated stress concentration.
3Reliability
If multilayer winding portions are distributed at multiple positions, then inductance is improved, but the complexity of wire arrangement increases
Solution Approach 1:
The patent applies segmentation by dividing the winding structure into multiple discrete multilayer winding portions distributed at different positions along the core. Each winding portion is a separate segment that contributes to the total inductance. This segmentation allows the wire to be arranged in a systematic pattern with regular spacing, reducing overall complexity compared to a single dense winding section.
Solution Approach 2:
The patent utilizes the axial dimension of the core by distributing multilayer winding portions along the length of the core rather than concentrating them at a single location. This spatial distribution in the axial dimension allows multiple winding sections to coexist without excessive wire crossing or complexity, while collectively providing the required inductance through additive magnetic effects.
Data Source
AI summary
In an inductor component, the winding return portions of multilayer winding portions that are embedded in a resin coating member present at positions that face a surface other than a winding core top surface of a winding core portion, and, of turns of a wire that constitute a first layer of each of the multilayer winding portions that is closest to the peripheral surface of the winding core portion, adjacent turns of the wire that are located between adjacent winding portions of the multilayer winding portions are in contact with each other or form a gap that is equal to or smaller than the radius of the wire.