O-ring Centering for Probe Substrate Thermal Stability
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Solution Overview
Problem
Existing modular probe arrays face issues with non-uniform thermal contact and hysteresis during temperature cycling due to the use of setscrews, leading to undesirable temperature variations and reduced probe performance.
Innovation Solution
The use of an O-ring to center the substrate within the mounting block, providing equal compression on all sides and eliminating the need for external forces, combined with set screws for positioning, enhances thermal isolation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If setscrews are used to position the substrate in the mounting block, then the substrate can be positioned and held in place, but non-uniform thermal contact and hysteresis occur during temperature cycling leading to undesirable temperature variations
Solution Approach 1:
The patent introduces a thermal interface material (TIM) as an intermediary between the substrate and mounting block. This TIM layer provides uniform thermal contact across the interface, eliminating the non-uniform thermal contact and hysteresis that occurred with direct setscrew contact. The TIM acts as a mediator that distributes thermal energy evenly while still allowing mechanical positioning.
Solution Approach 2:
The patent changes the physical state and properties of the contact interface by replacing direct rigid contact with a compliant thermal interface material. This parameter change allows the interface to adapt to thermal expansion and contraction during cycling, maintaining uniform contact pressure and eliminating hysteresis effects.
2Manufacturing precision
If setscrews are used to center the substrate, then positioning can be achieved, but lateral motion and hysteresis occur during thermal cycling reducing probe performance
Solution Approach 1:
The patent uses a compliant mounting material as an intermediary between the setscrews and the substrate. This material allows the setscrews to apply positioning forces while accommodating thermal expansion and contraction, preventing lateral motion and hysteresis that would otherwise occur with rigid direct contact.
Solution Approach 2:
The patent employs a flexible compliant mounting material that can deform elastically during thermal cycling. This flexibility absorbs dimensional changes without allowing the substrate to shift laterally, maintaining precise centering and probe alignment throughout temperature variations.
3Strength
If the substrate is in direct contact with the vertical face of the mounting block, then mechanical support is provided, but temperature variations in the springhead position occur
Solution Approach 1:
The patent replaces direct rigid contact between the substrate and mounting block with a flexible compliant mounting material. This material provides mechanical support through elastic deformation while thermally isolating the substrate, preventing temperature variations from affecting springhead position precision.
Solution Approach 2:
The compliant mounting material acts as a cushioning layer that absorbs and isolates thermal shocks and variations before they can affect the substrate and springhead assembly. This beforehand cushioning prevents temperature-induced position variations while maintaining mechanical support.
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 configuration maintains precise centering and reduces temperature variations, extending the life of interposer springs and improving thermal cycling performance by minimizing lateral motion and temperature-related issues.
Implementation Method 1
The O-ring provides equal and opposite compression on all four sides of the substrate at all temperatures
Implementation Method 2
The O-rings also help to thermally isolate the substrate from the mounting-block (as it is no longer in direct contact on the vertical surface). It lowers the temperature of the interposer springs
Data Source
AI summary
A modular probe array for making temporary electrical contact to devices under test is provided. The probe array includes multiple probe heads each having a substrate disposed within a mounting block. Improved thermal cycling performance is obtained by using an O-ring between the substrate and the mounting block. Optionally, set screws can be used in combination with the O-ring to set the position of the substrate in its mounting block.