Segmented Vertical Probes for High-Frequency Testing
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Solution Overview
Problem
Testing heads with short, rod-like probes less than 5000 μm in length face challenges in high frequency applications due to increased stiffness, which can lead to breaking of both the probes and contact pads, especially when attempting to establish electrical contact with devices under test.
Innovation Solution
The testing head incorporates vertical contact probes with openings along their length, reducing stiffness and pressure on contact pads, and includes auxiliary guides to define gaps where critical portions of the probes experience low bending stresses, thereby reducing the likelihood of breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the probe length is reduced to less than 5000 μm for high frequency applications, then the self-inductance is reduced improving high frequency performance, but the stiffness increases causing higher breaking risk and excessive contact force
Solution Approach 1:
The probe body is segmented by introducing longitudinal openings that divide the solid structure into multiple sections. This segmentation reduces the overall stiffness of the probe while maintaining its structural integrity, allowing the probe to be short enough for high frequency applications without becoming excessively rigid and prone to breaking.
Solution Approach 2:
The probe incorporates a porous or hollow structure through longitudinal openings along its body. This porous design reduces the mass and stiffness of the probe, enabling it to maintain adequate flexibility and reduce contact force on the device under test while still achieving the short length required for high frequency performance above 1000 MHz.
2Strength
If the probe stiffness is reduced to decrease contact force on contact pads, then the breaking risk is reduced, but the probe length must be increased which degrades high frequency performance
Solution Approach 1:
By segmenting the probe body through longitudinal openings, the probe achieves reduced stiffness and increased flexibility without requiring an increased length. The segmented structure allows the short probe to bend more easily and exert reduced contact force on the device under test while maintaining the short length necessary for high frequency performance.
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
This configuration allows for effective high-frequency testing with reduced risk of probe breakage and prolonged useful life, while maintaining adequate elasticity and minimizing the force exerted on contact pads, making it suitable for applications above 1000 MHz.
Implementation Method 1
The body of the contact probe may have a length less than 5000 μm and can have an opening extending along its length, suitable to define a plurality of arms parallel to each other and separated by the opening
Implementation Method 2
The auxiliary guide is suitable to define a gap not including the critical portion of the body of the contact probe, namely a zone more prone to breakings. Consequently, the critical portion of the body of the contact probe undergoes low or even no bending stresses with respect to the rest of the body
Data Source
AI summary
A testing head for functionality testing a device under test comprises a plurality of contact probes, each contact probe having a rod-like body having a preset length less than 5000 μm extending between a first and a second end, the second end being a contact tip and an opening extending all over its length and defining a plurality of arms, parallel to each other, separated by the opening and connected to the end portions of the contact probe, and an auxiliary guide, arranged transverse to the body and provided with suitable guide holes, the contact probes sliding through each of them, the auxiliary guide defining a gap including one end of the opening being a critical portion of the body and a zone more prone to breakings in the body undergoing low or even no bending stresses in the gap with respect to the rest of the body.