Interposer Ground Fencing for Harmonic Signal Isolation
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Solution Overview
Problem
Wireless communication devices face interference from harmonic signals generated by internal wired signals, which degrade communication quality by overlapping with wireless signals transmitted or received at antennas.
Innovation Solution
The use of an interposer with discontinuous inner and outer plating fences and strategically placed ground vias to block harmonic signals, forming a ground fence around signal vias, and optimizing the spacing between ground vias to reduce noise leakage and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If continuous plating fences are used to block harmonic signals, then signal interference is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The continuous plating fence is divided into multiple discrete segments with gaps between them. These segmented fences are positioned at specific locations around signal vias to block harmonic signals while allowing manufacturing processes to access underlying layers. The segmentation reduces manufacturing complexity compared to continuous plating while maintaining effective signal blocking through strategic placement.
Solution Approach 2:
Instead of applying uniform continuous plating throughout, the invention applies plating fences only at specific locations where harmonic signal blocking is needed. The plating fences are placed locally around signal vias that generate harmonic signals, with gaps in other areas to reduce manufacturing complexity and allow access to underlying circuit layers.
2Device complexity
If plating fences are made discontinuous with gaps, then manufacturing complexity is reduced, but signal blocking effectiveness decreases
Solution Approach 1:
The plating fences are positioned and configured in advance during PCB design and manufacturing to preemptively block harmonic signals before they can interfere with wireless signals. The fences are placed at strategic locations where harmonic signals are most likely to propagate, ensuring interference is blocked at the source rather than requiring complex post-manufacturing adjustments.
Solution Approach 2:
The plating fences act as intermediary structures between the signal vias that generate harmonic signals and the wireless signals that could be interfered with. These fences serve as a middle layer that blocks harmful harmonic signals while allowing the underlying signal vias to function normally and wireless signals to pass through unaffected areas.
3Object-affected harmful factors
If ground vias are placed close together to form effective ground fence, then signal blocking is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of requiring uniformly dense ground vias throughout the entire PCB, the invention applies ground fences only partially around specific signal vias that generate harmonic signals. The ground vias are concentrated at critical locations where harmonic signal blocking is most needed, providing effective interference reduction without requiring excessive manufacturing precision across the entire board.
Solution Approach 2:
The spacing between ground vias in the ground fence is optimized based on the specific frequency and characteristics of harmonic signals being blocked. Rather than using a fixed uniform spacing, the ground via parameters (spacing, diameter, depth) are adjusted to match the interference characteristics, achieving effective blocking with relaxed manufacturing tolerances.
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
Effectively reduces signal interference by blocking harmonic signals, maintaining communication quality above a certain threshold, particularly for millimeter wave frequencies, while minimizing additional component costs and manufacturing complexity.
Implementation Method 1
The discontinuous inner plating fence at least partially blocks the signal and includes a first gap. The discontinuous outer plating fence at least partially surrounds the discontinuous inner plating fence. The discontinuous outer plating fence at least partially blocks the signal and includes a second gap
Implementation Method 2
The multiple ground vias form a ground fence around the multiple signal vias. The spacing between each of the multiple ground vias is based at least in part on a degree of coupling between wireless signals communicated from the wireless communication board package and harmonic signals associated with the wired signals
Data Source
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AI summary
Techniques to reduce signal interference between wired signals communicated within an electronic device and wireless signals transmitted to or received from antennas of the electronic device are disclosed. The electronic device includes an interposer with an inner fence and an outer fence having offset gaps to prevent a pathway otherwise formed by overlapping tabs, where the pathway allows noise leakage from the wired signals. In some embodiments, the electronic device (e.g., in a main logic board package) includes a ground fencing of ground vias to prevent the noise leakage from harmonics associated with signal vias communicating the wired signals. The spacing between the ground vias is based on frequencies of signals that the ground vias are intended to block.