Rigid Probe With Compliant Cantilever for High-Power Wafer Testing
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Solution Overview
Problem
Wafer probing of high power integrated circuits with compliant bumps faces challenges such as loss of electrical contact due to insufficient compliance in rigid probes and limited pitch capability in compliant probes, leading to overheating and mechanical stress issues.
Innovation Solution
A probe design featuring a cantilever mechanism that deflects to maintain contact with compliant bumps, providing both the necessary force to initiate and maintain electrical contact while accommodating thermal and mechanical stresses, and being compact enough for high-density arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rigid probes are used, then manufacturing cost is reduced and array density is increased, but electrical contact is lost due to insufficient compliance
Solution Approach 1:
The probe structure incorporates a compliant section with specific geometric parameters (length, width, thickness) that provide controlled flexibility. This compliant section allows the probe to deform elastically under load, maintaining electrical contact with bumps despite thermal expansion or mechanical stress, while the overall probe remains relatively rigid for structural support and electrical conduction.
2Reliability
If compliant probes are used, then electrical contact reliability is improved, but probe length must be increased which causes overheating and poor electrical performance
Solution Approach 1:
The probe structure differentiates between regions: the compliant section is designed with specific dimensional properties (length L, width W, thickness T) to provide localized flexibility for maintaining contact, while the base and shaft portions maintain rigid properties for structural support and efficient electrical conduction. This localized compliance allows short overall probe length while ensuring reliable contact.
3Reliability
If compliant probes are used, then contact with non-planar bumps is achieved, but probe array density is limited due to longer length
Solution Approach 1:
The compliant section dimensions (length L, width W, thickness T) are optimized to provide sufficient compliance for contact reliability while minimizing overall probe length. This allows tighter spacing between adjacent probes in the array, increasing array density and enabling higher productivity in wafer probing applications.
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
The probe effectively maintains electrical contact during testing by flexing to follow chip movement and applying sufficient force to deform bumps, ensuring reliable contact without overheating or mechanical failure, even in high power applications.
Implementation Method 1
the cantilever configured to deflect from a first position to a second position in which a second end opposite the first end is in contact with the substrate and to move between the second position and the first position based on a movement of a compliant bump
Data Source
AI summary
A probe conducts testing of a circuit. The probe includes a base coupled to a substrate. The probe also includes a cantilever attached to the base at a first end, the cantilever deflecting from a first position to a second position in which a second end opposite the first end is in contact with the substrate and to move between the second position and the first position based on movement of a compliant bump of the circuit, and a probe tip attached to the cantilever at the second end, the probe tip maintaining contact with the compliant bump of the circuit.