Planar PCB Transformer Module for Low-Height Magnetic Coupling
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Solution Overview
Problem
The existing printed circuit board modules in automotive DC-DC converters face challenges due to the high overall height of wire-wound components, which limits space, increases manufacturing costs, and results in resonance issues with parasitic capacitance and electromagnetic waves, as well as difficulties in securing leakage inductors.
Innovation Solution
A printed circuit board module configuration with multiple layers, including a first printed circuit board and additional layers with smaller cross-sectional area coils and cores, allowing for a wider space and reduced manufacturing costs by optimizing coil arrangement and using insulation layers and air gaps to manage electromagnetic interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire-wound components with iron cores are used, then magnetic coupling is achieved, but the overall height of components increases
Solution Approach 1:
The patent replaces traditional wire-wound mechanical components with planar coils fabricated on printed circuit boards. This substitution eliminates the need for bulky iron cores and wire winding, achieving magnetic coupling through flat spiral or rectangular coil patterns etched onto the PCB surface, thereby dramatically reducing component height while maintaining inductance functionality.
Solution Approach 2:
The invention transitions from three-dimensional wire-wound components to two-dimensional planar coils on PCB surfaces. By laying out coils in flat patterns (spiral, rectangular, or interdigitated designs) on the board surface, the magnetic field generation and coupling functions are achieved without vertical stacking, thus reducing overall height while preserving inductance values.
2Area of stationary object
If the printed circuit board is configured in multiple layers to increase coil arrangement area, then manufacturing cost increases
Solution Approach 1:
The patent divides the coil structure into multiple separate PCB layers, each containing partial coil patterns. These segmented coil sections are distributed across different layers and connected through vias, allowing the total inductance to be achieved without requiring a single large continuous area on one layer, thereby reducing manufacturing complexity and cost.
Solution Approach 2:
The invention implements nested coil configurations where smaller coil patterns are placed within or around larger coil patterns on the same or adjacent PCB layers. This nesting approach maximizes the use of available board area, allowing multiple inductors to share space efficiently and reducing the overall footprint without increasing manufacturing difficulty.
3Area of stationary object
If the coil arrangement area increases, then capacitance component increases causing resonance with parasitic components
Solution Approach 1:
The patent applies different trace widths, spacing, and pattern geometries to different regions of the coil structure to control local capacitance distribution. By optimizing the local geometry (such as using tighter spacing in critical areas and wider spacing elsewhere), the overall parasitic capacitance is minimized while maintaining the required inductance, thereby reducing resonance issues.
Solution Approach 2:
The invention introduces ground planes and shielding structures as intermediary elements between adjacent coils and between coil layers. These intermediary ground planes act as electromagnetic shields that reduce mutual capacitance and parasitic coupling between nearby conductors, thereby minimizing resonance effects while allowing closer coil placement.
4Reliability
If high magnetic coupling through core is used, then leakage inductor cannot be secured
Solution Approach 1:
The patent employs asymmetric coil configurations where the primary and secondary coils have different geometries, turn ratios, or coupling distances. This asymmetry allows independent optimization of coupled inductance (for power transfer) and leakage inductance (for current limit and protection functions), enabling both high magnetic coupling and adequate leakage inductance to coexist in the same transformer structure.
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 secures a wider space for metal patterns, lowers manufacturing costs, and reduces electromagnetic interference, while facilitating better magnetic coupling and leakage inductor management.
Implementation Method 1
a core passing through the first printed circuit board to the third printed circuit board, wherein the second printed circuit board includes a first coil, the third printed circuit board includes a second coil
Data Source
AI summary
A printed circuit board module comprises: a first printed circuit board; a second printed circuit board arranged on one surface of the first printed circuit board; a third printed circuit board arranged on the other surface of the first printed circuit board; and a core passing through the first printed circuit board to the third printed circuit board, wherein the second printed circuit board includes a first coil, the third printed circuit board includes a second coil, and the cross-sectional area of the second printed circuit board and the third printed circuit board is less than the cross-sectional area of the first printed circuit board.