Tiled Membrane Space Transformer for Vertical Probe Arrays

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Solution Overview

Problem

Conventional vertical probe assemblies face issues with thermal stress and low fabrication yield due to monolithic fabrication of guide plates and space transformers, which limits their performance and reliability, especially in testing electronic devices and circuits.

Innovation Solution

The space transformer and metal ground plane plates are fabricated in several small pieces and assembled to form the complete structure, allowing for better thermal management and increased manufacturing yield, while maintaining signal integrity and repairability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the space transformer and guide plates are fabricated as single monolithic parts, then structural integrity is improved, but thermal stress increases and fabrication yield decreases

Engineering Contradiction:
Improvestructural integrityVSAvoidfabrication yield
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The space transformer is divided into multiple separate guide plates instead of being fabricated as a single monolithic part. Each guide plate can be independently fabricated and assembled, which reduces thermal stress and improves fabrication yield while maintaining structural integrity through the stacked configuration.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If the space transformer is fabricated as a single monolithic part, then manufacturing simplicity is improved, but thermal stress management deteriorates

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidthermal stress
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The monolithic space transformer is segmented into multiple guide plates that can be fabricated separately using standard PCB processes. This segmentation allows each plate to expand and contract independently with temperature changes, significantly reducing thermal stress while maintaining manufacturing simplicity through modular assembly.

Inventive Principle:
Principle #1Segmentation

3Reliability

If the space transformer is fabricated in multiple pieces, then fabrication yield is improved, but device complexity increases

Engineering Contradiction:
Improvefabrication yieldVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The space transformer is segmented into multiple guide plates that are stacked and secured together. While this improves fabrication yield by allowing independent manufacturing of each plate, it increases assembly complexity. The patent addresses this by providing a systematic stacking and securing method that manages the complexity of assembling multiple pieces into a functional unit.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3676619B1Vertical probe array having a tiled membrane space transformer
Publication Date: 2023.09.27 FORMFACTOR INC
  • EP3676619B1 patent drawingFigure 1~2
  • EP3676619B1 patent drawingFigure 3~4
  • EP3676619B1 patent drawingFigure 5~6

AI summary

Vertical probe heads having a space transformer laterally tiled into several sections are provided. This change relative to conventional approaches improves manufacturing yield. These probe heads can include metal ground planes, and in embodiments where the ground planes are provided as separate metal plates parallel to the guide plates, the metal plates can also be laterally tiled into several sections. Such tiling of metal plates improves manufacturing yield and alleviates thermal mismatch issues. Probes are not mechanically connected to the space transformer, which facilitates replacement of individual probes of an array.