Wiring Substrate Ground Layer Openings for Noise Suppression
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Solution Overview
Problem
Existing wiring substrates fail to adequately suppress radiation noise and crosstalk noise, especially when transmitting high-speed differential signals, due to insufficient shielding effects from conventional ground layers with mesh patterns.
Innovation Solution
A wiring substrate design featuring a ground layer with openings arranged in a specific configuration, where the length of the openings along the signal lines (L1) is four times or more than the length orthogonal to it (L2), and L2 is equal to or less than the distance between differential signal lines (L3), reducing return route inductance and increasing mutual inductance for effective noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional mesh pattern ground layer is used, then the shielding effect is provided, but the radiation noise and crosstalk noise are not adequately suppressed
Solution Approach 1:
The ground layer is segmented into multiple isolated ground lines instead of a continuous mesh pattern. These ground lines are arranged in a specific configuration with spacing and dimensions designed to provide effective noise suppression while maintaining signal integrity
Solution Approach 2:
The ground lines are positioned specifically adjacent to differential signal line pairs, creating localized shielding zones where noise suppression is most critical. The ground lines have specific width and spacing dimensions optimized for their local electromagnetic environment
2Loss of energy
If the ground layer has a mesh pattern, then shielding is provided, but return route inductance is not sufficiently reduced
Solution Approach 1:
The continuous ground layer is divided into discrete ground lines with controlled dimensions and spacing. This segmentation allows optimization of the return current path inductance by creating multiple localized return routes rather than relying on a single mesh structure
Solution Approach 2:
The ground lines have specific width and spacing parameters that are optimized to reduce return route inductance. The dimensions and spacing are carefully controlled to achieve the desired electrical characteristics while simplifying the overall ground layer structure
3Speed
If high-speed differential signals are transmitted, then data communication speed is improved, but radiation noise and crosstalk noise increase
Solution Approach 1:
Ground lines are positioned adjacent to differential signal line pairs before noise can radiate or couple to adjacent signals. This preliminary shielding arrangement prevents noise generation at its source by providing localized reference planes and return current paths
Solution Approach 2:
The ground lines are designed to interact with the electromagnetic fields of the differential signals in a controlled manner, converting potential harmful radiation into beneficial localized shielding effects that actually improve signal integrity at high speeds
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
The proposed configuration significantly reduces radiation noise and crosstalk noise, even at high-speed signal transmission rates, while maintaining flexibility and communication integrity.
Implementation Method 1
reducing return route inductance and increasing mutual inductance for effective noise suppression
Data Source
AI summary
A wiring substrate which includes a base member having a first surface, a first differential signal line disposed on the first surface of the base member and a second differential signal line disposed adjacent to the first differential signal line on the first surface of the base member. A ground layer which faces the first and second differential signal lines, has a plurality of openings continuously arranged along a predetermined direction. In a planar view of the wiring substrate, where a length of each of the plurality of openings in a direction along the signal lines is a length L1, a length of the opening in a direction orthogonal to Li is a length L2, and a distance between the first and second differential signal lines is a length L3, L1 is equal to or greater than four times L2, and L2 is equal to or less than L3.