IC Package Ground Via Clusters for Single-Ended Bus Crosstalk
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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 forming clusters of ground vias adjacent to each other, which can be surrounded by signal vias in specific patterns like hexagonal or triangular arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional ground pins are utilized for ground connections to isolate signals and reduce crosstalk, then crosstalk between signals is reduced, but package form factor increases and manufacturing cost increases
Solution Approach 1:
The patent transitions from adding ground pins in the horizontal plane (increasing package area) to stacking ground vias vertically in clusters (utilizing the vertical dimension). This allows multiple ground connections to be formed within the same footprint by arranging vias in layers above and below signal vias, effectively reducing crosstalk without expanding the package form factor.
Solution Approach 2:
The patent implements nested ground via clusters where ground vias are arranged in concentric patterns around signal vias, with inner ground vias surrounded by outer ground vias. This nested configuration maximizes the ground connection density within a compact area, providing effective signal isolation without requiring additional package area.
2Object-affected harmful factors
If additional ground pins are utilized for ground connections to isolate signals and reduce crosstalk, then crosstalk between signals is reduced, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple ground vias into clustered groups that are formed as integrated structures during the packaging process. By merging multiple ground connections into unified via clusters rather than treating them as separate pins, the manufacturing process is simplified and cost is reduced while still achieving effective signal isolation.
Solution Approach 2:
The patent utilizes the vertical dimension to stack ground vias in multiple layers, allowing more ground connections to be formed within the same horizontal footprint. This vertical stacking approach increases ground connection density without requiring additional package pins, thereby reducing manufacturing complexity and cost compared to adding more horizontal pins.
3Object-affected harmful factors
If ground via clustering is implemented to reduce crosstalk, then near-end and far-end crosstalk are reduced by 50% or more, but via cluster formation complexity increases
Solution Approach 1:
The patent applies ground via clustering selectively at specific locations where signal isolation is most critical, such as near signal sources and signal terminations. Rather than uniformly clustering all vias throughout the package, the invention focuses ground via clusters at key positions, effectively reducing crosstalk while minimizing the overall complexity of via formation.
Solution Approach 2:
The patent divides the ground via structure into discrete clusters that are independently formed and positioned around specific signal vias. Each ground via cluster is a self-contained unit that can be formed using standard via fabrication processes, making the overall complex structure manageable through modular segmentation rather than requiring a single complex formation process.
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.