Recessed Substrate Layout for Via-Free High-Speed Signal Routing
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Solution Overview
Problem
Electronic devices with high-speed interfaces face electromagnetic interference (EMI) issues due to reflections from via holes and reference ground asymmetry, which affect signal integrity and performance.
Innovation Solution
The electronic device system features a substrate with recess areas for the main processor chip and external device connecting portions, where signals are wired as an inner layer without via holes, ensuring direct contact and improved EMI characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via holes are used to wire signals between layers, then electrical connection between layers is achieved, but electromagnetic interference and signal reflections occur degrading signal integrity
Solution Approach 1:
The patent extracts and eliminates via holes from the signal path by implementing a substrate with recess areas that allow direct planar wiring. The connector and processor are positioned in recessed areas, enabling signal transmission through the substrate plane without penetrating via holes, thus removing the source of EMI and reflections.
Solution Approach 2:
The patent transitions from vertical signal routing through via holes to horizontal planar routing within the substrate plane. By creating recess areas and positioning components on the substrate surface, signals travel through the substrate thickness direction rather than requiring through-hole connections, changing the dimensional path of signal transmission.
2Reliability
If back-drilling is performed to remove via hole stubs, then signal reflections are reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the problematic via hole stubs from the design by eliminating via holes entirely from the signal path. Instead of manufacturing via holes and then performing back-drilling to remove stubs, the design directly avoids via hole creation in the signal transmission path, simplifying the manufacturing process.
Solution Approach 2:
The substrate structure is designed in advance with recess areas and planar wiring paths that prevent via hole stub formation from the beginning. This preliminary design approach eliminates the need for subsequent back-drilling operations, as the structure is configured to avoid the problem rather than correct it later.
3Reliability
If EMI shielding materials are added to reduce electromagnetic interference, then signal integrity improves, but device complexity and cost increase
Solution Approach 1:
The patent converts the substrate structure itself into the EMI solution by using the recess areas and planar wiring configuration to inherently reduce electromagnetic interference. Instead of adding separate shielding materials, the design uses the structural arrangement to minimize EMI generation and propagation, making the substrate structure beneficial for EMI reduction.
4Ease of manufacture
If reference ground asymmetry is present in via hole structures, then manufacturing is simplified, but signal integrity deteriorates due to EMI
Solution Approach 1:
The patent removes via holes from the signal path, eliminating the reference ground asymmetry problem associated with via hole structures. The planar wiring approach in recess areas provides symmetric reference grounds without the geometric asymmetries inherent in via hole configurations.
Data Source
AI summary
Provided is an electronic device system including a first electronic device including a first substrate, a second electronic device including a second substrate, and a data transferer including a first connector and a second connector, the data transferer configured to connect the first electronic device and the second electronic device, the first substrate including the first recess area and the second recess area spaced apart from the first recess area, and the first recess area and the second recess area are at a same depth.