Wafer Level Probe Array Pin Rotation Constraint
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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 bias force, and a rigid up-stop surface to maintain precise contact with wafer-level test pads, allowing for uniform and aligned electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wafer-level testing methods are used, then testing can be performed on semiconductor wafers, but the testing accuracy and reliability are insufficient compared to IC package testing
Solution Approach 1:
The patent changes the physical parameters of the contact structure by transitioning from conventional probe tips to pins with lateral flanges that engage with channels. This structural parameter change enables precise positioning and prevents rotation, thereby improving both measurement precision and testing reliability at the wafer level
Solution Approach 2:
The patent introduces an intermediary structure - the pin with lateral flange and channel engagement system - that mediates between the testing equipment and the wafer contact points. This intermediary provides mechanical constraint and alignment, enabling accurate and reliable electrical contact similar to IC package testing
2Manufacturing precision
If probe tips are used for wafer-level testing, then electrical contact can be made with test pads, but uniform bias force and alignment are difficult to maintain
Solution Approach 1:
The pin structure is segmented into distinct functional elements: the longitudinal pin body for electrical contact, lateral flanges for mechanical engagement, and the channel structure for positioning. This segmentation allows each element to perform its specific function optimally, achieving precise alignment without excessive overall complexity
Solution Approach 2:
The patent creates equipotential mechanical conditions by having multiple pins with lateral flanges engage with corresponding channels at the same depth. This ensures uniform bias force across all contact points, maintaining consistent electrical contact pressure and alignment throughout the array
3Measurement precision
If pins without rotational constraint are used, then simple contact can be made, but pin rotation occurs which compromises testing accuracy
Solution Approach 1:
The pin structure employs asymmetry through the lateral flanges that extend from one side of the pin body. This asymmetric feature engages with the channel to prevent rotation while maintaining simple insertion. The asymmetric design provides rotational constraint without complicating the basic pin-contact operation
Solution Approach 2:
The channel-flange engagement mechanism is self-aligning and self-constraining. As the pin is inserted into the channel, the lateral flange automatically engages with the channel walls, providing rotational constraint without requiring additional alignment steps or complex positioning mechanisms
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 before segmentation, ensuring uniform bias force and preventing pin rotation, thereby improving testing accuracy and reliability.
Implementation Method 1
an elastomeric material of predetermined height when in an uncompressed state, said material surrounding the pins to create said bias force
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.