Bent Substrate Inductor with Closed Magnetic Circuit
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Solution Overview
Problem
Existing inductor elements face challenges in reducing direct-current resistance (DCR) and increasing self-resonant frequency while maintaining a small size and thickness, leading to a narrowed frequency band for high-frequency applications.
Innovation Solution
The inductor element is designed with a plurality of coils arranged on the same plane, connected in series, and an insulating substrate is bent to create a closed magnetic circuit, reducing characteristic variations and allowing for a line-segment conductor pattern on a different layer to prevent breakage due to tensile stress, thereby reducing DCR and enhancing self-resonant frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the line width of conductor patterns is reduced to decrease the size of the inductor element, then the area occupied by the inductor element is reduced, but the direct-current resistance (DCR) is increased
Solution Approach 1:
The inductor element is divided into a first inductor and a second inductor that are connected in series. Each inductor has its own conductor pattern forming a coil, allowing the total inductance to be achieved with shorter individual conductor paths, thereby reducing DCR while maintaining a compact overall area.
Solution Approach 2:
The patent utilizes a bent insulating substrate to create a three-dimensional arrangement where conductor patterns are formed on different surfaces and layers. This spatial configuration allows the conductor patterns to achieve the required inductance with shorter path lengths by utilizing vertical and lateral dimensions, reducing DCR while keeping the footprint area small.
2Area of moving object
If conductor patterns are formed in multiple layers to reduce the size of the inductor element, then the area occupied is reduced, but the interlayer capacitance increases which lowers the self-resonant frequency
Solution Approach 1:
The inductor is segmented into two separate inductors connected in series, each formed on different layers of the insulating substrate. This segmentation reduces the interlayer capacitance between adjacent conductor segments compared to a single continuous multi-layer pattern, thereby maintaining a higher self-resonant frequency while achieving compact size.
Solution Approach 2:
The insulating substrate acts as an intermediary with controlled dielectric properties between the conductor patterns on different layers. By optimizing the insulating material and its thickness, the interlayer capacitance is minimized, allowing multi-layer construction without significantly lowering the self-resonant frequency.
3Stability of the object's composition
If the insulating substrate is bent to create a closed magnetic circuit, then the magnetic coupling between adjacent coils is improved, but the line-segment conductor pattern may break due to tensile stress
Solution Approach 1:
The insulating substrate has different mechanical properties in different regions: it is bent in specific areas to create the closed magnetic circuit geometry, while remaining flat or less stressed in areas where the line-segment conductor patterns are located. This localized bending approach maintains magnetic coupling benefits while avoiding stress concentration on conductor patterns.
Solution Approach 2:
The design anticipates the tensile stress that will occur when the insulating substrate is bent and positions the line-segment conductor patterns in regions that will experience minimal or compressive stress rather than tensile stress. This preemptive placement prevents conductor pattern breakage before the bending is applied.
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 configuration achieves a higher self-resonant frequency, widens the frequency band, reduces unwanted magnetic coupling, and allows for more flexible arrangement and reduced size and thickness of the inductor element.
Implementation Method 1
coils that are adjacent on the identical plane define a closed magnetic circuit (a magnetic flux that interlinks coils that are adjacent in the planar direction define a loop)
Implementation Method 2
a coil defined by the conductor pattern, in which the coil includes a plurality of coils arranged on an identical plane and connected in series
Implementation Method 3
An increase in interline capacitance and interlayer capacitance increases the floating capacitance per obtained inductance, which lowers the self-resonant frequency
Data Source
AI summary
An inductor element includes a resin substrate which is an insulating substrate including conductor patterns, and coils defined by the conductor patterns. Two coils are arranged on the same plane, and connected in series. Adjacent coils define a closed magnetic circuit. That is, the winding direction and the connection of the coils are determined such that magnetic flux that interlinks coils that are adjacent in the planar direction define a loop. There are also provided an inductor bridge and a high-frequency filter that include the inductor element.