Multilayer Substrate Mesh Ground Openings Signal Integrity
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Solution Overview
Problem
In multilayer substrates, the degradation of electrical characteristics in signal lines due to overlap with mesh ground openings leads to variations in high-frequency characteristics, restricting the performance of semiconductor devices.
Innovation Solution
The multilayer substrate design incorporates a mesh ground with differently shaped openings, where second openings have a shorter path length for return currents, reducing overlap and variation in electrical characteristics by altering their form based on signal line orientations and positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mesh ground with uniform openings is used, then the ground provides continuous electrical connection, but signal lines overlapping with openings experience degradation in electrical characteristics
Solution Approach 1:
The patent applies local quality by making the ground openings non-uniform - specifically, openings positioned beneath signal lines have different dimensions than other openings. This local modification ensures that signal lines do not overlap with openings, eliminating the harmful effect of electrical characteristic degradation while maintaining the mesh ground's overall functionality.
2Reliability
If signal lines are routed to avoid ground openings, then electrical characteristics are improved, but layout flexibility and routing options are reduced
Solution Approach 1:
Instead of routing signal lines to avoid ground openings, the patent inverts the approach by making the ground openings adapt to the signal line positions. The openings beneath signal lines are configured with different dimensions, effectively making the ground structure conform to the signal layout rather than vice versa, thus maintaining both electrical performance and layout flexibility.
3Reliability
If ground openings are made smaller to reduce overlap effects, then electrical characteristics improve, but the ground's ability to shield and provide return paths is reduced
Solution Approach 1:
The patent applies local quality by differentiating opening dimensions based on location: openings beneath signal lines have different dimensions to prevent overlap and maintain electrical characteristics, while other openings maintain standard dimensions to preserve shielding and return path functionality. This localized differentiation resolves the contradiction between electrical performance and ground effectiveness.
Data Source
AI summary
According to one embodiment, there is provided a multilayer substrate including a ground layer and a signal layer. The ground layer includes a mesh ground having multiple openings. The signal layer is laid above the ground layer and including multiple signal lines. The multiple openings include first openings and second openings. The first openings overlap a first signal line from among the multiple signal lines when seen through in a direction perpendicular to a surface of the multilayer substrate. The second openings overlap the first signal line when seen through in the direction perpendicular to the surface of the multilayer substrate. The first openings have a first form, and the second openings have a second form different from the first form.