Planar Spiral Coil With Variable Line Widths
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Solution Overview
Problem
The miniaturization of electronic devices has led to a need for compact, high-performance power inductors with reduced thickness and cost, while maintaining reliability and efficiency, as existing thin-film inductors face challenges in uniform plating growth and increased aspect ratios, which can result in short circuits and reduced coil efficiency.
Innovation Solution
A coil component design featuring a planar spiral coil pattern with a first conductive layer and a second conductive layer, where the line width of the outermost and innermost patterns differs from the internal patterns, allowing for uniform plating growth and reduced process variations, thereby increasing the coil area and inductance while minimizing direct current resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thin-film inductor structure is used to reduce thickness, then the device thickness is reduced, but plating uniformity deteriorates and short circuits increase
Solution Approach 1:
The coil structure is divided into multiple segments with different line widths. The outermost and innermost patterns have a first line width, while intermediate patterns have a second line width that is different from the first. This segmentation allows each segment to be optimized independently, with narrower outer patterns reducing aspect ratio and improving plating uniformity, while maintaining overall coil functionality and reducing short circuit risk in thin-film structures
Solution Approach 2:
Different regions of the coil pattern are assigned different line widths based on their specific requirements. The outermost and innermost patterns use a first line width optimized for plating uniformity and aspect ratio control, while intermediate patterns use a second line width optimized for inductance and coil area. This local quality approach ensures each region contributes optimally to overall performance while maintaining reliability in the reduced-thickness structure
2Power
If the coil area is increased to improve inductance, then the inductance increases, but the device thickness increases
Solution Approach 1:
The coil pattern utilizes planar dimensionality optimization by varying line widths across different radial positions. Instead of increasing thickness to achieve higher inductance, the design optimizes the two-dimensional coil area through strategic line width variations, with narrower outer patterns and wider intermediate patterns maximizing the effective coil area within the planar footprint while maintaining thin-film thickness
Solution Approach 2:
The line width parameter is changed across different coil patterns to optimize performance. By varying the line width from outermost to innermost patterns, the design achieves higher effective coil area and inductance within the same planar space without increasing thickness, effectively using parameter variation to decouple inductance enhancement from thickness increase
3Power
If the aspect ratio is increased to improve coil efficiency, then the coil efficiency improves, but manufacturing precision deteriorates
Solution Approach 1:
The coil is segmented into patterns with different aspect ratios. Outermost and innermost patterns have a first aspect ratio with narrower line widths, while intermediate patterns have a second aspect ratio with wider line widths. This segmentation prevents any single high-aspect-ratio pattern from dominating, thereby maintaining plating uniformity while preserving overall coil efficiency through the combined effect of multiple patterns with optimized aspect ratios
Solution Approach 2:
The aspect ratio parameter is varied across different coil patterns rather than maintaining a uniform high aspect ratio throughout. By changing the line width parameter in different radial positions, the design achieves optimal coil efficiency through increased effective area while keeping individual pattern aspect ratios at manageable levels that ensure good plating uniformity and manufacturing precision
Data Source
AI summary
A coil component includes a body including a magnetic material, a support member disposed inside the body, and a coil pattern disposed on the support member inside the body. The coil pattern includes a first conductive layer, having a planar spiral shape, and a second conductive layer, having a line width greater than a thickness thereof, while covering the first conductive layer. When viewed from a surface of the body cut in thickness and width directions, a line width of each of outermost and innermost patterns of the first conductive layer is different from a line width of at least one internal pattern disposed between the outermost and innermost patterns.