Probe Head Orientation for Impedance Matching and Contact Prevention
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Solution Overview
Problem
The challenge in high-frequency/high-speed testing is to improve impedance matching between probe pairs while preventing probe contact and short circuits, especially in differential pairs, due to the increasing demand for closer probe spacing with higher data transmission rates.
Innovation Solution
A probe head design with probes arranged perpendicular to their buckling direction, utilizing a guide plate system to accommodate probes, allowing for closer spacing and reducing the risk of interference and short circuits, while maintaining impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch between probe pairs is reduced to improve impedance matching for high-speed signal transmission, then the characteristic impedance decreases and signal transmission improves, but the risk of probe mutual contact and short circuits increases
Solution Approach 1:
The patent changes the arrangement dimension of probes by introducing a rotational angle θ relative to the buckling direction. Instead of arranging probes parallel or perpendicular to the buckling direction, the probes are arranged at an optimized angle θ that ranges from 0 to 90 degrees, creating a new dimensional parameter for probe positioning. This angular dimension allows simultaneous optimization of pitch distance for impedance matching and spatial separation for preventing probe contact.
Solution Approach 2:
The patent introduces a specific parameter θ (rotation angle) that defines the orientation of the probe pair relative to the buckling direction. By optimizing this parameter within the range of 0 to 90 degrees, the patent achieves a balance between minimizing pitch for impedance matching and maximizing separation for preventing probe contact. The cross-sectional shape parameter (rectangular with specific aspect ratio) is also optimized to reduce buckling while maintaining compact dimensions.
2Reliability
If the pitch between probe pairs is reduced to meet high-frequency testing requirements, then impedance matching improves, but manufacturing precision requirements increase to prevent short circuits
Solution Approach 1:
The patent adds a rotational angle dimension θ to the traditional linear pitch optimization. Instead of only adjusting the distance between probes, the system now optimizes both the pitch distance and the angular orientation relative to the buckling direction. This dual-parameter approach (pitch + angle θ) provides an additional degree of freedom that decouples the trade-off between impedance matching and manufacturing precision.
Solution Approach 2:
The patent employs a composite structural approach by combining rectangular cross-section probes (for reduced buckling) with guide holes that constrain probe movement. The guide plate structure with precisely positioned guide holes provides mechanical guidance that compensates for manufacturing tolerances, effectively reducing the impact of manufacturing precision variations on final probe positioning.
3Productivity
If probes are arranged closer together to accommodate more elements on the device under test, then testing capability increases, but the probability of probe contact during testing increases
Solution Approach 1:
The patent utilizes the angular dimension θ to arrange probe pairs at an optimized orientation relative to the buckling direction. This angular arrangement ensures that when probes experience buckling during contact with the device under test, the probes tend to buckle away from each other rather than toward each other, reducing contact probability. This allows denser probe arrangements while maintaining reliability.
Solution Approach 2:
The patent introduces asymmetry in the probe arrangement by using a specific rotation angle θ that is not 0 or 90 degrees. The rectangular cross-section of probes is also oriented at this angle relative to the pitch direction, creating an asymmetric configuration that optimizes both impedance characteristics and mechanical separation during operation, reducing the probability of mutual contact.
Data Source
AI summary
A probe head includes a pair of pre-bent probes and a guide plate. The pair of probes electrically connects the electronic device integrated within a semiconductor wafer to the testing equipment. Each probe includes a tip, bottom, and body. The tip has a contact tip that contacts the corresponding contact area on the electronic device during testing. The body extends between the tip and bottom along a longitudinal development axis, and the cross-section of the body is perpendicular to the longitudinal development axis. The guide plate has a pair of guide holes configured to slidably accommodate the pair of probes. The pair of probes is arranged in a direction parallel to the cross-section, and the direction is substantially perpendicular to the buckling direction of the probes. The cross-section of each probe is substantially rectangular, and the center line of the two cross-sections passes through the short sides of each cross-section.