Probe Head Guide-Plate Routing for Loopback Signal Integrity
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Solution Overview
Problem
Existing circuit probe test systems suffer from poor signal integrity during loopback testing due to long loopback signal paths, which are typically routed through the substrate portion of the probe card, leading to poorer performance.
Innovation Solution
The implementation of a probe card design that routes loopback signals through conductive traces on and/or within a guide plate, reducing the total length of the loopback signal path by using probe pins that extend through openings in the guide plate and are electrically connected by these traces, thereby minimizing signal travel distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If loopback signals are routed through the substrate portion of the probe card, then the signal path is established, but the signal integrity deteriorates due to long signal path length
Solution Approach 1:
The patent routes loopback signals through the guide plate structure rather than through the substrate portion, effectively changing the spatial dimension and path of signal transmission. The conductive traces are formed on or within the guide plate, allowing signals to travel a shorter distance through a different structural dimension, thereby improving signal integrity while reducing path length.
Solution Approach 2:
The invention extracts the loopback signal routing function from the substrate portion and relocates it to the guide plate. By separating the signal routing function from the original substrate path and placing it in the guide plate structure, the patent achieves a shorter signal path while maintaining the necessary electrical connections between probe pins.
2Length of moving object
If probe pins extend through openings in the guide plate with conductive traces, then the loopback signal path length is reduced, but the device complexity increases
Solution Approach 1:
The guide plate is designed to serve multiple functions: it provides mechanical support for the probe pins, maintains alignment through openings, and simultaneously serves as the signal routing path through conductive traces. By making the guide plate multi-functional, the patent reduces the need for separate signal routing structures, thereby reducing overall device complexity while achieving shorter signal paths.
Solution Approach 2:
The patent merges the mechanical guide function and the electrical signal routing function into a single integrated structure. The guide plate combines both the physical guidance of probe pins and the conductive pathways for signals, eliminating the need for separate routing layers or structures and simplifying the overall probe head design.
Data Source
AI summary
A probe card for a circuit probe test system and methods of fabrication thereof. The probe card includes a substrate portion, and a probe head including a guide plate located below the substrate portion and having a plurality of openings through the guide plate, and a conductive trace on the guide plate that extends between a pair of the openings. A plurality of probe pins extend through the openings through the guide plate, where a pair of probe pins are electrically connected by the conductive trace to form a loopback signal path. Accordingly, the loopback signals may be routed through the conductive trace located on and/or within the guide plate rather than through the substrate portion of the probe card. This may significantly reduce the total length of the loopback signal path, which may thereby improve the signal integrity (SI) during loopback testing of a device-under-test.