Semiconductor Package Via Layout for Differential Signal Integrity
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Solution Overview
Problem
Existing wiring boards face challenges in maintaining differential signal integrity due to limitations in via stacking, leading to increased signal loss and distortion, particularly when stacked vias are restricted to two or three per stack, necessitating improved routing techniques for differential signal transmission.
Innovation Solution
The implementation of staggered via structures in differential signal transmission lines, where connection structures are alternately disposed along vertical axes and spaced apart horizontally, ensuring electrical insulation and non-overlapping configurations to reduce signal loss and maintain differential mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stacked vias are continuously formed according to process rules, then signal transmission path is established, but signal loss increases when vias must be staggered
Solution Approach 1:
The patent transitions from a two-dimensional via arrangement (stacked vias in vertical columns) to a three-dimensional staggered via configuration where vias are offset both horizontally and vertically. This dimensional change allows the differential signal transmission line to maintain impedance control and reduce signal loss by distributing vias across multiple layers in a staggered pattern rather than stacking them directly, thereby resolving the contradiction between establishing continuous signal paths and minimizing signal loss.
2Adaptability or versatility
If staggered vias are used to reduce signal loss, then routing flexibility improves, but differential mode maintenance becomes more difficult
Solution Approach 1:
The patent employs asymmetric via placement within the staggered configuration, where vias are intentionally positioned at different horizontal offsets across multiple layers while maintaining overall symmetry in the differential pair structure. This asymmetric yet controlled placement provides routing flexibility to navigate around obstacles and maintain appropriate spacing, while the differential pair's overall symmetry ensures that both signals experience similar impedance conditions, thereby maintaining differential mode.
3Loss of energy
If vias are spaced apart horizontally to reduce signal loss, then routing area increases, but connection structure complexity increases
Solution Approach 1:
The patent segments the via connection structure into multiple discrete via holes distributed across different layers in a staggered pattern, rather than using a single continuous via. Each via is spaced apart horizontally from its counterparts on adjacent layers, which reduces signal loss by minimizing via-induced distortion. The segmentation approach allows each via to be independently optimized for impedance control while collectively forming the complete signal transmission path, thereby managing complexity through modular construction.
Data Source
AI summary
A semiconductor package includes a wiring board including at least one pair of connection structures electrically connecting at least one pair of differential signal transmission lines and at least one pair of differential signal transmission terminals, respectively. The at least one pair of connection structures includes first via structures staggered in a vertical direction, at least one first connection line electrically connecting the first via structures, second via structures staggered in the vertical direction, and at least one second connection line electrically connecting the second via structures. The at least one first connection line is spaced apart from the at least one second connection line in the vertical direction and electrically insulated therefrom, and intersects the at least one second connection line in the vertical direction.