Shielding Vertical Probe Heads Crosstalk

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Solution Overview

Problem

Crosstalk between probes in vertical probe arrays is a significant issue, especially at high frequencies, due to the fixed spacing of probes, which limits the ability to meet strict crosstalk requirements in RF device testing.

Innovation Solution

The introduction of a metal carrier with pockets between the guide plates, where probes are disposed, provides additional isolation by creating a grounded plane between probes, effectively reducing crosstalk by 10 dB or more.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If probes are spaced further apart to reduce crosstalk, then crosstalk is reduced, but probe array density and testing capability are degraded

Engineering Contradiction:
Improvecrosstalk between probesVSAvoidprobe array density
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent introduces a vertical dimension by placing a grounded metal carrier between the top and bottom guide plates, creating pockets that extend vertically through the carrier. This third-dimensional approach to shielding allows probes to remain closely spaced horizontally while achieving crosstalk reduction through vertical isolation, thus resolving the contradiction between probe density and crosstalk reduction.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The grounded metal carrier acts as an intermediary structure between adjacent probes, providing electromagnetic shielding through its grounded pockets. This intermediate element isolates probes from each other without requiring increased spacing, enabling both high probe density and low crosstalk by mediating the electromagnetic interaction between neighboring probes.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a metal carrier with pockets is added to reduce crosstalk, then crosstalk is reduced, but device complexity increases

Engineering Contradiction:
Improvecrosstalk between probesVSAvoidprobe array structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The metal carrier serves multiple functions simultaneously: it provides mechanical support for the probes, creates isolated pockets for electromagnetic shielding, and when grounded, acts as a reference plane for signal return paths. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving crosstalk reduction.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the shielding function with the existing guide plate structure by positioning the metal carrier between the top and bottom guide plates. The carrier integrates with the mechanical probe positioning system while adding electromagnetic shielding capability, thus combining structural support and crosstalk reduction into a unified structure that minimizes overall complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

This solution significantly reduces crosstalk between probes, enhancing the ability to meet stringent crosstalk requirements, thereby improving the performance of probe cards in high-frequency testing applications.

Implementation Method 1

disposing a metal carrier that has two or more pockets between the guide plates... the metal carrier itself is grounded... probes passing through different pockets are further isolated from each other by the intervening ground plane provided by the metal carrier

Methodology Applied
Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentEP3568705B1Shielding for vertical probe heads
Publication Date: 2025.05.28 FORMFACTOR INC
  • EP3568705B1 patent drawingFigure 1A~1B
  • EP3568705B1 patent drawingFigure 2A~2B
  • EP3568705B1 patent drawingFigure 3~4

AI summary

Crosstalk between probes in a vertical probe array is reduced by providing a grounded metal carrier disposed between the guide plates of the probe array. The metal carrier includes pockets that are laterally separated from each other by the metal carrier. Probes in different pockets are thereby electrically shielded from each other.