Multilayer Resin Substrate Layout for Flatness and Low Stray Capacitance
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Solution Overview
Problem
Existing multilayer flexible substrates face issues with deteriorated flatness and increased stray capacitance due to changes in via porosity or shape, which affect their performance and functionality.
Innovation Solution
A multilayer resin substrate design featuring floating electrodes positioned between signal and ground electrodes, with enlarged via-receiving joints and controlled electrode distances, to maintain substrate flatness and reduce stray capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the porosity of vias is increased to ensure flexibility in the flexible region, then flexibility is improved, but substrate flatness deteriorates due to distortion
Solution Approach 1:
The patent applies different via structures to different regions: the rigid region has via-conductors with smaller cross-sectional areas, while the flexible region has via-conductors with larger cross-sectional areas. This local differentiation allows each region to have optimal properties for its function while maintaining overall substrate flatness.
Solution Approach 2:
The patent changes the cross-sectional area parameter of via-conductors based on location. By adjusting this physical parameter, the patent achieves both flexibility in the flexible region (larger via-cross-sectional area) and flatness in the rigid region (smaller via-cross-sectional area), resolving the contradiction between these two requirements.
2Adaptability or versatility
If the shape of via-receiving portion is changed to ensure flexibility, then flexibility is improved, but stray capacitance increases
Solution Approach 1:
The patent introduces floating electrodes specifically in the flexible region between signal electrodes and ground electrodes. This local addition provides flexibility while the floating electrode's electrical isolation prevents increased stray capacitance, as it does not form capacitive coupling with adjacent conductors.
Solution Approach 2:
The floating electrode acts as an intermediary structure that mechanically enables flexibility while electrically preventing harmful capacitive effects. By being electrically isolated (floating), it mediates between the mechanical requirement for flexibility and the electrical requirement to minimize stray capacitance.
Data Source
AI summary
A multilayer resin substrate includes first and second substrates joined to overlap each other, a first signal electrode on a joint surface between the first and second substrates, a first via-conductor in the first substrate and joined to the first signal electrode, a first ground electrode in or on the second substrate and overlapping the first signal electrode, a first floating electrode in the second substrate and between the first signal electrode and the first ground electrode. The first signal electrode includes a first joint joined to the first via-conductor and a wiring portion extending in a signal transmission direction. In a line-width direction transverse to the signal transmission direction, the first joint has a line width greater than that of the wiring portion. When viewed in the thickness direction, the first floating electrode overlaps the first joint of the first signal electrode.