Wiring Board Ground Openings for RF Impedance Matching
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Solution Overview
Problem
Wiring boards struggle to transmit high-frequency radio-frequency signals with minimal loss and maintain impedance matching, particularly in structures with shield layers and insulating films.
Innovation Solution
A wiring board design featuring specific configurations of insulating layers, ground conductors, and signal conductors, including overlapping end portions and openings, to adjust impedance and maintain resonance frequency, with varying opening sizes and placements to reduce impedance decrease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shield layer with openings is provided to adjust impedance, then impedance matching is improved, but signal transmission loss increases due to discontinuities in the shield layer
Solution Approach 1:
The patent applies local quality by making the opening size variable along the signal conductor. The first opening (at the jointing portion) is larger than the second opening (along the signal line), creating different local impedance characteristics where needed. This resolves the contradiction by providing strong impedance matching at the jointing portion with the larger opening while minimizing signal loss along the transmission path with the smaller opening.
2Manufacturing precision
If the opening size is increased to reduce impedance decrease at jointing portions, then impedance matching is improved, but the shield effectiveness is reduced
Solution Approach 1:
The patent implements local quality by differentiating opening sizes at different locations. The larger first opening is positioned only at the jointing portion where impedance matching is critical, while the smaller second opening is positioned along the signal line where shield effectiveness is more important. This spatial differentiation resolves the contradiction between impedance matching and shield effectiveness.
Solution Approach 2:
The patent segments the opening structure into multiple distinct openings (first opening and second opening) with different sizes and positions. This segmentation allows independent optimization of each opening's function: the first opening addresses impedance matching at the jointing portion, while the second opening maintains shield effectiveness along the signal path.
Data Source
AI summary
A wiring board includes a first insulating layer, a second insulating layer, a first ground conductor, and a first signal conductor. The first insulating layer includes a first upper surface and a first lower surface. The second insulating layer is positioned on the first insulating layer and includes a second upper surface and a second lower surface. The first ground conductor is positioned on the first lower surface and includes a first opening and a second opening. The first signal conductor includes a first line positioned on the first upper surface and a second line positioned on the second lower surface. The first line includes a first end portion and a first line portion. The second line includes a second end portion electrically connected to the first end portion, and a second line portion. The first opening is larger in area than the second opening in a planar view.