Coaxial Loopback Probe Head for 120 GHz Signal Integrity
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Solution Overview
Problem
Current probe cards fail to meet high-frequency loopback test requirements for electronic devices in high-speed networks due to inadequate control of signal reflection and loss, and are affected by dielectric effects in signal transmission channels.
Innovation Solution
A probe head design incorporating vertical and coaxial probes, where coaxial probes transmit signals with a ground signal path, providing improved signal integrity and flexibility for precise contact with devices under test, allowing for stable and accurate loopback testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If vertical probes or membrane probes are used for high-frequency testing, then the testing can be performed with simple probe structures, but the signal reflection and loss cannot be effectively controlled at frequencies like 120 GHz
Solution Approach 1:
The probe card is divided into multiple functional regions: a first region with vertical probes for general signal transmission, and a second region with coaxial probes specifically for high-frequency loopback testing. This segmentation allows each region to be optimized for its specific function, with the coaxial probes providing controlled impedance and reduced signal reflection for high-frequency applications.
Solution Approach 2:
Different probe types are used in different locations based on testing requirements. The coaxial probes are specifically deployed in the second region where high-frequency loopback testing is performed, providing local optimization of signal transmission quality where it is most needed, while maintaining simpler vertical probes in other areas.
2Device complexity
If traditional vertical probes and membrane probes are used, then the probe design is simple, but they cannot meet the geometric shape and impedance matching requirements for high-frequency signals
Solution Approach 1:
The probe card design segments the probing function into vertical probes for general use and coaxial probes for high-frequency applications requiring precise impedance matching. The coaxial probes are specifically designed with controlled geometric shapes and impedance characteristics to meet the stringent requirements of 120 GHz testing.
Solution Approach 2:
The design changes the geometric parameters and structural configuration of the probes in the second region to achieve proper impedance matching for high-frequency signals. The coaxial probe structure with its specific dimensions and configuration provides the necessary impedance control that traditional vertical probes cannot achieve.
3Device complexity
If traditional probe designs are used, then the structure is simple, but they cannot effectively handle the propagation characteristics of high-frequency signals affected by dielectric effects
Solution Approach 1:
The probe card is segmented into regions with different probe types optimized for different signal frequency ranges. The coaxial probes in the second region are specifically designed to handle high-frequency signals by providing controlled impedance pathways that minimize the impact of dielectric effects and improve signal propagation characteristics.
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 design achieves stable and precise high-frequency loopback testing by minimizing signal interference and ensuring accurate contact, meeting the requirements of high-speed network applications.
Implementation Method 1
The plurality of electrical conductors located close to each other, i.e. those electrically connected with the first and second tips respectively, can be used to transmit the ground signal and the testing signal respectively to attain the coaxial probe effect
Implementation Method 2
The lower end portion of the vertical probe is adapted to contact the electrically conductive contacts of the device under test
Data Source
AI summary
A probe head includes a probe seat, vertical probes, and coaxial probes. The vertical probes are slidably inserted in guiding holes of the probe seat, and have lower end portions for contacting electrically conductive contacts of a device under test. The coaxial probe includes a probe main body provided from the outside to the inside thereof coaxially with an outer conductor, a dielectric layer and an inner conductor in order, and a tip unit disposed at a lower end portion of the probe main body and including first and second tips electrically connected with the outer and inner conductors respectively for contacting electrically conductive contacts of the device under test. The coaxial probes include first and second loopback probes composing a loopback probe pair for being configured as a part of a loopback test path. As a result, the present invention meets the high-frequency loopback test requirements.