Fine Pitch Probe Array With Enclosed Flexures
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Solution Overview
Problem
Existing probe arrays face significant challenges in preventing shorting when used with densely packed, fine-pitch 2-D contact arrays due to probe deformation during operation, as they are prone to making contact with each other.
Innovation Solution
The use of electrically insulating guide plates with vertically folded or coiled probe flexures, where the flexures are enclosed within guide plate holes, preventing contact between probes and ensuring they remain electrically isolated, along with rigid extensions beyond the guide plate to maintain alignment and prevent shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If probes are arranged in fine pitch for densely packed 2-D contact arrays, then probing capability is improved, but probe shorting increases due to deformation during operation
Solution Approach 1:
The probe structure is segmented into distinct functional zones: a flexible lower portion for contact compliance and a rigid upper portion for structural stability. This segmentation allows the flexible part to deform during probing while the rigid part maintains fixed positioning, preventing probe-to-probe shorting even at fine pitches
Solution Approach 2:
The flexible probe portion is nested within the guide plate hole, with the rigid extension protruding through. This nested configuration constrains the flexible section's movement space while allowing necessary deformation, effectively preventing lateral displacement that would cause shorting
2Reliability
If probe flexures are made flexible to accommodate contact force, then probing reliability is improved, but probe deformation increases leading to shorting
Solution Approach 1:
Different portions of the probe have different mechanical properties: the lower portion is made flexible to accommodate contact force variations and maintain reliable probing, while the upper portion is made rigid to maintain stable positioning and prevent deformation-induced shorting. This local differentiation of mechanical properties resolves the contradiction between flexibility and stability
3Ease of manufacture
If guide plate holes are enlarged to accommodate probe flexures, then probe fabrication is simplified, but probe isolation is reduced increasing shorting risk
Solution Approach 1:
The solution moves the isolation function from the horizontal plane (hole size) to the vertical dimension. The guide plate hole size can be larger for easier fabrication, while the rigid extension protruding through the plate provides vertical constraint and lateral isolation, effectively decoupling hole size from isolation performance
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 effectively prevents probe shorting at ultra-low pitches by keeping probe flexures isolated, allowing for reliable probing of densely packed 2-D contact arrays while maintaining mechanical integrity and thermal management through heat sink integration.
Implementation Method 1
Each probe includes an upper rigid portion and a lower flexible portion extending between the guide plate and the chip. The flexible portion may be formed as a spring or other elastic structure.
Data Source
AI summary
Probes suitable for use with densely packed fine-pitch 2-D contact arrays are provided by use of an electrically insulating guide plate in connection with vertical probes, where the vertical probes have probe flexures that are either vertically folded sections, or coils having a horizontal axis. Preferably, the probes are configured such that the probe flexures are inside the guide plate holes, and the parts of the probes extending past the guide plate are relatively rigid. This configuration alleviates problems associate with probe shorting, because the probe flexures are enclosed by the guide plate holes, and are therefore unable to come into contact with flexures from other probes during probing.