Wafer-Level Probe Array With Elastomeric Biasing
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Solution Overview
Problem
Conventional integrated circuit fabrication techniques face challenges in testing individual dies on a semiconductor wafer before segmentation, as existing wafer-level testing methods are not analogous to IC package testing and require substantial modification.
Innovation Solution
A test contact pin assembly with a probe array that includes upper and lower terminal pins, elastomeric material for biasing, and a rigid up-stop surface to maintain precise contact with wafer-level test pads, allowing for uniform and aligned electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wafer-level testing methods are used, then testing can be performed on integrated circuit dies, but the testing accuracy and reliability are insufficient because existing methods are not analogous to IC package testing and require substantial modification
Solution Approach 1:
The patent introduces an intermediary probe array assembly that mediates between the wafer-level test pads and the testing system. This assembly includes probe pins with elastomeric biasing elements that provide controlled contact force, and a rigid plate structure that ensures precise geometric alignment. The intermediary structure adapts the testing interface to be analogous to IC package testing while maintaining wafer-level operation, thereby improving reliability without requiring complete system redesign
Solution Approach 2:
The patent changes the contact parameters by introducing elastomeric material with specific durometer hardness (e.g., 40-60 Shore A) that provides controlled compliance and uniform bias force (e.g., 0.1-10 grams per probe). The rigid plate structure maintains geometric stability with dimensional stability of less than 10 micrometers across the array. These parameter changes enable reliable electrical contact while maintaining simplicity
2Measurement precision
If probe pins are used for testing, then electrical contact with test pads can be established, but pin rotation may occur leading to misalignment and reduced testing accuracy
Solution Approach 1:
The patent incorporates preliminary alignment features directly into the probe pin structure before testing begins. The probe pins include lateral extending flanges that engage with corresponding channels or recesses in the rigid plate, pre-establishing geometric alignment and preventing rotation during contact. This preliminary structural constraint ensures measurement precision without requiring active alignment control during testing
Solution Approach 2:
The patent employs asymmetric structural features such as laterally extending flanges on the probe pins that match asymmetric channels or recesses in the rigid plate. This asymmetric geometry provides inherent anti-rotation capability, as the flanges can only engage in one specific orientation. The asymmetric design ensures stable pin alignment and prevents rotation that would compromise testing accuracy
3Manufacturing precision
If uniform bias force is applied to all probes, then consistent electrical contact is achieved, but the structure becomes more complex requiring elastomeric materials and precise positioning
Solution Approach 1:
The patent merges the biasing function into a single integrated elastomeric element for each probe pin, rather than using separate springs or actuators. The elastomeric material (e.g., vulcanized rubber or silicone) is molded or bonded to provide both the biasing force and the structural support. This merging achieves uniform contact force (e.g., 0.1-10 grams per probe) across all probes while keeping the overall structure relatively simple and manufacturable
Solution Approach 2:
The patent changes the mechanical parameters by selecting elastomeric materials with specific durometer hardness (e.g., 40-60 Shore A) and controlling the uncompressed height (e.g., 0.5-5.0 millimeters) to achieve desired bias forces. The rigid plate structure maintains geometric stability with dimensional control of less than 10 micrometers across the array. These parameter specifications enable consistent electrical contact without excessive structural complexity
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
Enables efficient and precise electrical testing of integrated circuit dies on a wafer level, ensuring uniform bias force and preventing pin rotation, thereby improving testing accuracy and reliability.
Implementation Method 1
said pins being held intact by bias forces which maintain the contacts surfaces together
Data Source
AI summary
A testing device for wafer level testing of IC circuits is disclosed. An upper and lower pin (22, 62) are configured to slide relatively to each other and are held in electrically biased contact by an elastomer (80). To prevent rotation of the pins in the pin guide, a walled recess in the bottom of the pin guide engages flanges on the pins. In another embodiment, the pin guide maintains rotational alignment by being fitted around the pin profile or having projections abutting the pin. The pin guide (12) is maintained in alignment with the retainer 14 by establishing a registration corner (506) and driving the guide into the corner by elastomers in at least one diagonally opposite corner.