Ground Via Cluster Layout for Low-Crosstalk IC Package Routing
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Solution Overview
Problem
High-speed signal-ended buses in integrated circuit assemblies face limitations in data rate due to crosstalk, particularly in vertical interconnects, which can be mitigated by additional ground connections but at the cost of increased package size and manufacturing costs.
Innovation Solution
Implementing ground via clustering, where multiple ground vias are clustered together to enhance coupling between signals and grounds, reducing crosstalk without increasing the package form factor, by using existing substrate design rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional ground connections are used to isolate signals and reduce crosstalk, then crosstalk between signals is reduced, but package form factor increases
Solution Approach 1:
Multiple ground vias are merged into a single clustered ground via structure. The patent combines several ground connections into one consolidated via cluster that serves multiple signal lines simultaneously, reducing the total number of individual ground vias needed while maintaining effective ground coupling for crosstalk mitigation.
Solution Approach 2:
The ground via cluster extends vertically through multiple substrate layers, utilizing the vertical dimension to provide enhanced ground coupling. By stacking ground vias across different layers in a clustered configuration, the patent achieves improved signal isolation without expanding the horizontal package footprint.
2Object-affected harmful factors
If additional ground connections are used to isolate signals and reduce crosstalk, then crosstalk between signals is reduced, but manufacturing cost increases
Solution Approach 1:
The patent consolidates multiple ground via functions into single via clusters, reducing the total via count and associated manufacturing steps. This merging approach simplifies the fabrication process by requiring fewer drilling, plating, and etching operations compared to implementing individual ground vias for each signal line.
Solution Approach 2:
Each ground via cluster serves multiple signal lines simultaneously, providing universal ground coupling functionality. A single via cluster can ground multiple adjacent signal traces, making the structure multi-functional and reducing the overall complexity of the ground distribution network.
3Reliability
If ground via clustering is implemented to reduce crosstalk, then signal-to-noise ratio improves, but device complexity increases
Solution Approach 1:
Ground via clusters are selectively placed at specific locations where crosstalk is most problematic, such as near high-speed signal lines or at transitions between layers. This localized approach provides enhanced ground coupling only where needed, rather than uniformly across the entire substrate, thereby reducing overall device complexity.
Solution Approach 2:
The ground via cluster structure nests multiple ground vias within a compact configuration, with vias positioned in close proximity to each other and to the signal lines they serve. This nested arrangement provides comprehensive ground coverage while maintaining a compact footprint and simplified routing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces both far-end and near-end crosstalk by 50% or more, improves signal-to-noise ratio, and maintains the package form factor without additional interconnect structures, effectively addressing the crosstalk challenge.
Implementation Method 1
the via cluster provides a low-inductance path to ground
Implementation Method 2
enhance coupling between signals and grounds, reducing crosstalk
Data Source
AI summary
Embodiments of the present disclosure are directed towards techniques and configurations for ground via clustering for crosstalk mitigation in integrated circuit (IC) assemblies. In some embodiments, an IC package assembly may include a first package substrate configured to route input/output (I/O) signals and ground between a die and a second package substrate. The first package substrate may include a plurality of contacts disposed on one side of the first package substrate and at least two ground vias of a same layer of vias, and the at least two ground vias may form a cluster of ground vias electrically coupled with an individual contact. Other embodiments may be described and/or claimed.