Multilevel Package Substrate Box Shield for Low-Crosstalk Routing
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Solution Overview
Problem
High-speed electronic devices and systems face challenges in achieving low crosstalk and electromagnetic interference (EMI) performance, especially with increasing multi-channel capability and higher IO counts, particularly in compact designs where traditional shielding methods like stitched via arrays are insufficient.
Innovation Solution
A multilevel package substrate with a conductive box shield that surrounds conductive signal traces, comprising multiple levels of conductive trace and via features with dielectric layers, providing contiguous metal shielding similar to a coaxial cable structure, effectively reducing crosstalk and EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If stitched via arrays are used to shield electric fields, then some EMI reduction is achieved, but the vias leak electrical fields and do not provide complete shielding
Solution Approach 1:
The shielding structure is segmented into multiple discrete conductive elements (via features and trace features) distributed across multiple levels of the package substrate. These segmented conductive elements work together to block electromagnetic fields while maintaining substrate functionality.
Solution Approach 2:
The shielding approach transitions from a two-dimensional via array to a three-dimensional multi-level structure with conductive elements on different substrate levels connected by conductive vias, creating volumetric shielding that more effectively blocks electromagnetic field leakage.
2Adaptability or versatility
If multi-channel capability and higher IO counts are added to high-speed devices, then device functionality is improved, but crosstalk and EMI performance deteriorate
Solution Approach 1:
Conductive shielding features are selectively placed in specific locations around high-speed signal traces where crosstalk is most problematic. The shielding density and configuration are optimized locally based on the specific signal routing and interference patterns of each multi-channel interface.
Solution Approach 2:
Conductive shielding structures serve as intermediary elements between adjacent high-speed signal channels, acting as electromagnetic field barriers that prevent direct coupling between channels while allowing the multi-channel functionality to operate.
3Volume of moving object
If compact system designs are implemented, then device size is reduced, but EMI shielding becomes more difficult
Solution Approach 1:
The shielding structure is nested within the compact package substrate itself, with conductive shielding elements integrated into the substrate layers rather than adding external shielding components. This nested approach provides effective EMI shielding while maintaining the compact form factor.
Solution Approach 2:
The shielding solution utilizes the vertical dimension by implementing conductive shielding elements on multiple substrate levels connected through vias, creating three-dimensional shielding within the compact lateral footprint of the device.
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
The solution achieves low crosstalk and EMI performance comparable to coaxial cables, with crosstalk reduced by up to 12 dB at 10 GHz, enhancing shielding effectiveness in high-speed digital video interface circuits and RF amplifiers without increasing manufacturing complexity or cost.
Implementation Method 1
a conductive box shield that surrounds a portion of the conductive signal trace
Implementation Method 2
a first dielectric layer on and between the first conductive trace features and between the first conductive via features
Data Source
AI summary
An electronic device includes a multilevel package substrate having a first level, a second level, a third level, a conductive signal trace that extends in the second level, and a conductive box shield that surrounds a portion of the conductive signal trace. The electronic device includes a semiconductor die attached to the multilevel package substrate and having a conductive structure coupled to an end of the conductive signal trace. The electronic device includes a package structure that encloses the semiconductor die and a portion of the multilevel package substrate.