Package Substrate Ground Stub Layout for Signal Crosstalk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor memory module products require higher signal density, crosstalk interference occurs between signals, distorting them and degrading product characteristics, and maximizing signal line distance to minimize crosstalk is limited by spatial constraints.
Innovation Solution
A package substrate with sequentially stacked insulating layers, including a first signal line, a ground line, and a ground stub that extends from the ground pad toward the signal via or pad, with a length-to-wavelength ratio of 0.005 to 0.05, to reduce noise and provide a return path for signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If signal density is increased to meet higher specifications, then productivity and device functionality improve, but crosstalk interference increases causing signal distortion and degraded characteristics
Solution Approach 1:
The patent introduces a ground stub as an intermediary element between signal lines to mitigate crosstalk interference. The ground stub acts as a mediator that provides a controlled impedance path and reduces electromagnetic coupling between adjacent signal lines, thereby maintaining high signal density while minimizing harmful interference effects.
Solution Approach 2:
The patent modifies the ground line structure by adding a ground stub with specific dimensional parameters (length, width, position) to change the electrical characteristics of the grounding system. By adjusting these parameters, the impedance matching and noise reduction performance are optimized, allowing high signal density without excessive crosstalk.
2Object-affected harmful factors
If distance between signal lines is maximized to reduce crosstalk, then signal characteristics improve, but spatial constraints and device area increase
Solution Approach 1:
The patent addresses the spatial constraint by introducing the ground stub that extends in a direction perpendicular to the main signal line orientation. This dimensional approach allows noise reduction without increasing the planar footprint, as the ground stub utilizes the vertical or lateral dimension to provide shielding and impedance control.
Solution Approach 2:
By carefully controlling the parameters of the ground stub (length ratio L/λ between 0.005 to 0.05, width, and position relative to signal lines), the patent achieves effective crosstalk reduction within compact dimensions. The parameter optimization allows noise mitigation without requiring excessive spacing between signal lines.
3Object-affected harmful factors
If ground stub length is increased to improve noise reduction, then signal characteristics improve, but device complexity and manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges for the ground stub, particularly limiting the length-to-wavelength ratio (L/λ) to 0.005 to 0.05. This parameter constraint provides an optimal balance between noise reduction effectiveness and manufacturing feasibility, ensuring that the ground stub is sufficiently long to provide shielding but not so long as to create excessive manufacturing complexity.
Data Source
AI summary
A package substrate includes a plurality of sequentially stacked insulating layers, a first signal line configured to transmit a first signal therethrough, and a ground line. The first signal line including a first signal via at least partially penetrating the plurality of insulating layers, a first signal pad provided at one end of the first signal via in any selected one of the insulating layers, and a first signal wiring extending from the first signal pad in the selected insulating layer. The ground line including a ground via at least partially penetrating the plurality of insulating layers, a ground pad provided at one end of the ground via in the selected insulating layer, a ground wiring extending from the ground pad in the selected insulating layer, and a ground stub extending from the ground pad toward the first signal via or the first signal pad.