Stubless Fly-by Wiring for Semiconductor Signal Integrity
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Solution Overview
Problem
The fly-by topology in semiconductor devices faces challenges with signal integrity due to the need for multiple signal wires crossing over on the substrate, leading to increased stub lengths and crosstalk noise, especially in systems with fewer layers where fly-by wires cannot be provided on internal layers, resulting in degraded signal transmission at higher data rates.
Innovation Solution
The implementation of a stubless fly-by wiring structure where fly-by wires connect terminals on the rear surface of semiconductor packages without branching, allowing for non-branching signal paths that reduce stub length and prevent signal degradation, achieved by arranging terminals and signal regions on the semiconductor device to enable fly-by wires on the upper surface without internal vias or stubs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fly-by wires are provided on the upper surface of the substrate, then wire routing complexity is reduced, but stub length increases causing signal degradation
Solution Approach 1:
The patent moves fly-by wires from the upper surface to the rear surface of the substrate, utilizing the third dimension (substrate thickness) to resolve the conflict. This allows wires to be routed on the rear surface without creating stubs on the upper surface, thereby maintaining signal integrity while simplifying overall routing architecture.
Solution Approach 2:
Instead of routing fly-by wires from the front to the rear surface (conventional approach), the patent inverts the routing direction by extending wires from the rear surface to connect terminals. This inversion eliminates the need for stubs that would form if wires originated from the front surface.
2Adaptability or versatility
If multiple signal wires cross over on the substrate surface, then connectivity is achieved, but crosstalk noise increases
Solution Approach 1:
The patent extracts the fly-by wires from the upper surface where they would cross other signals and cause crosstalk. By moving these wires to the rear surface, the harmful crossing interactions are eliminated while the essential connectivity function is preserved through the substrate.
3Reliability
If internal layers are used for fly-by wires, then stub length is reduced, but manufacturing complexity increases in systems with fewer layers
Solution Approach 1:
The patent creates a copy of the routing architecture by providing similar wiring capabilities on the rear surface as would be available on internal layers. This allows systems with fewer layers to achieve the same signal integrity benefits without requiring complex multi-layer internal routing structures.
Data Source
AI summary
A device includes: a wiring board having first and second surfaces opposing each other; and a plurality of memory packages on the first surface. The wiring board includes: a first set of terminals on the first surface; a plurality of second sets of terminals on the first surface; and a plurality of first signal lines. The terminals of the first set receive respective ones of a plurality of first signals supplied from a control device. Each of the second sets is provided for a corresponding one of the memory packages. The terminals of each of the second sets contact the corresponding one of the memory packages. The first signal lines extend from respective ones of the terminals of the first set while coupling respective ones of the terminals of each of the second sets. The first signal lines extend on the first surface without extending in the wiring board.