Multilayer Wiring Board Displacement Current Return Path
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Solution Overview
Problem
Current multilayer wiring boards face challenges in reducing signal attenuation and managing return currents efficiently, particularly due to high impedance in signal return paths, which affects the performance of semiconductor devices.
Innovation Solution
The multilayer wiring board design includes a first power supply layer adjacent to a ground layer with a dielectric interposed, allowing return currents to flow as displacement currents, reducing impedance and signal attenuation by providing a dedicated path for low-frequency components through capacitors, and an independent second power supply layer for the second element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ground layer is used as the return path for signal current, then the return current can be provided, but the impedance becomes high causing signal attenuation
Solution Approach 1:
The patent divides the return path into two segments: a ground layer for high-frequency signal return and a power supply layer for low-frequency return current. This segmentation allows each layer to optimize its function, with the power supply layer providing a low-impedance path for low-frequency components, thereby reducing overall signal attenuation.
Solution Approach 2:
The patent utilizes the vertical dimension by stacking the power supply layer adjacent to the ground layer with a dielectric layer in between. This three-dimensional arrangement creates a capacitive coupling that provides a low-impedance return path for low-frequency currents, effectively reducing signal attenuation without increasing lateral trace length.
2Object-affected harmful factors
If a power supply layer is placed adjacent to the ground layer with dielectric layer, then low-frequency return current path is provided, but the structure becomes more complex
Solution Approach 1:
The power supply layer serves dual functions: it provides power to mounted components and simultaneously acts as a return path for low-frequency displacement current. This multi-functionality reduces the need for separate dedicated return paths, thereby managing structural complexity while improving electrical performance.
3Object-affected harmful factors
If displacement current flows between ground layer and power supply layer, then return current is provided with lower impedance, but electromagnetic interference may increase
Solution Approach 1:
The dielectric layer acts as an intermediary between the ground layer and power supply layer, enabling capacitive coupling for displacement current while providing electrical isolation. This intermediary structure allows low-frequency return current to flow with low impedance while the ground layer continues to provide a stable reference potential, minimizing radiation noise.
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 reduces signal attenuation and improves current density in the return path, suppressing dissipation and radiation noise, while allowing continuous power supply to the second element even when the first element is stopped.
Implementation Method 1
The first power supply layer causes the return current that flows through the ground layer to return to the first element through the first power supply electrode as a displacement current between the ground layer and the first power supply layer
Data Source
AI summary
A multilayer wiring board includes a signal electrode, a first power supply electrode, and a ground electrode, which are connected to a first element that outputs a signal, an electrode connected to a second element that receives the signal, a ground layer that serves as a return path for a return current of the signal, a first power supply layer that is disposed adjacent to the ground layer with a dielectric layer interposed therebetween and supplies electric power to the first element, and a second power supply layer that is provided independently of the first power supply layer and supplies electric power to the second element. The first power supply layer causes the return current to return to the first element through the first power supply electrode as a displacement current between the ground layer and the first power supply layer.