Probe Assembly Grounding Layer Removal for Bandwidth Preservation
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Solution Overview
Problem
Conventional probe structures for differential signal testing on printed circuit boards with no grounding points are not designed, leading to issues with radiation resonance and bandwidth reduction due to the presence of grounding probes.
Innovation Solution
A probe assembly with a dielectric layer, signal lines, and pogo pins, where the grounding layers are strategically positioned to avoid coupling with the pogo pins, reducing radiation resonance and maintaining effective bandwidth by minimizing the grounding layers on both sides of the pogo pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grounding probes are used in conventional probe structures, then signal reference and stability are improved, but the probe cannot be applied to printed circuit boards without grounding points and causes radiation resonance that reduces bandwidth
Solution Approach 1:
The patent removes the grounding probe component from the probe structure, extracting only the necessary signal testing functionality. The probe assembly includes signal probes but deliberately excludes grounding probes, allowing it to be applied to PCBs without grounding points while maintaining signal integrity through alternative design approaches.
Solution Approach 2:
The patent applies different structural characteristics to different parts of the probe assembly. The signal probes have specific geometric configurations and spacing arrangements optimized for differential signal testing, while the absence of grounding probes creates localized field distributions that reduce radiation resonance. The probe structure is tailored locally to match the specific requirements of ground-less PCB test contacts.
2Object-affected harmful factors
If grounding layers are positioned close to signal lines for shielding, then electromagnetic interference protection is improved, but radiation resonance occurs that reduces effective bandwidth
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the signal lines and any surrounding grounding structures. This dielectric medium provides electrical isolation and controls the electromagnetic field distribution, preventing direct coupling that would cause radiation resonance while still allowing for necessary shielding effects through controlled impedance design.
Solution Approach 2:
The patent optimizes geometric parameters of the probe structure, including signal line spacing, probe tip dimensions, and dielectric layer thickness, to control impedance and minimize radiation. By carefully adjusting these parameters, the design achieves electromagnetic interference protection without the resonant effects that occur in conventional grounded probe structures.
Data Source
AI summary
A probe assembly, adapted to test high-speed signal transmission lines of printed circuit boards, includes two pogo pins for providing high-frequency differential test signals, and both sides of the pogo pin include no metal layer (grounding layer). Experiments have found that when the two pogo pins test a to-be-tested object, the test signal will be coupled to the metal layers on both sides of the pogo pins to generate a radiation resonance, resulting in a loss of the test signal on a specific frequency band, and further reducing the effective bandwidth of the probe assembly. The metal layers on both sides of the pogo pins of the probe assembly are reduced, so that the foregoing radiation resonance phenomenon can be avoided.