Flexible Membrane Probe Card for High-Frequency Signal Integrity
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Solution Overview
Problem
Probe cards with short contact probes used for high-frequency applications face challenges in maintaining proper contact without causing breakage of the probes or the contact pads due to increased rigidity and self-inductance issues, leading to potential damage during testing.
Innovation Solution
The probe card incorporates micro contact probes with one end abutting a flexible membrane, where contact elements act as damping support, allowing for reduced pressure and flexibility to prevent breakage, and conductive tracks for signal routing, ensuring effective high-frequency signal transmission without noise addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact probes are made short for high-frequency applications, then self-inductance is reduced and signal quality is improved, but rigidity increases causing breakage risk
Solution Approach 1:
The patent introduces a flexible membrane with conductive tracks that replaces traditional rigid contact probes. The membrane's flexibility allows it to deform during contact, absorbing stress and preventing breakage, while the conductive tracks maintain low self-inductance for high-frequency signal transmission. This directly resolves the contradiction by providing both flexibility and electrical performance.
Solution Approach 2:
The patent changes the physical state and material properties of the contact structure from rigid metal probes to a flexible membrane with specific mechanical and electrical characteristics. By adjusting the membrane's thickness, material composition, and conductive track geometry, the system achieves optimal balance between flexibility (to prevent breakage) and electrical performance (low self-inductance) for high-frequency applications.
2Reliability
If contact probes are made short for high-frequency applications, then self-inductance is reduced, but contact pressure control becomes difficult leading to pad damage
Solution Approach 1:
The flexible membrane inherently provides compliance through its ability to deform during contact. This flexibility allows the membrane to adapt to surface variations and distribute contact pressure evenly, preventing localized stress concentrations that could damage contact pads. The membrane's elastic properties enable it to absorb excess force while maintaining reliable electrical contact for high-frequency signals.
Solution Approach 2:
The flexible membrane acts as an intermediary between the rigid probe card structure and the device under test. It mediates the interaction by providing a compliant interface that controls contact pressure, protecting both the probe and the device while ensuring reliable signal transmission. The membrane's intermediate position allows it to absorb mechanical stress and regulate force distribution.
3Stability of the object's composition
If traditional rigid probe structures are used, then structural stability is maintained, but high-frequency signal transmission is degraded due to self-inductance
Solution Approach 1:
The flexible membrane with integrated conductive tracks replaces traditional rigid probe structures. The membrane provides sufficient structural stability through its tensioned configuration and support mechanisms, while the thin-film conductive tracks minimize self-inductance for high-frequency signal transmission. This configuration maintains mechanical stability while enabling reliable high-frequency performance.
Solution Approach 2:
The patent transitions from three-dimensional rigid metal probe structures to a two-dimensional flexible membrane configuration. This dimensional change allows the conductive paths to be optimized as thin traces with minimal loop areas, significantly reducing self-inductance. The membrane's planar structure maintains stability while enabling superior high-frequency signal transmission 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 solution effectively reduces the risk of breakage of both the micro contact probes and contact pads while maintaining proper contact, enabling reliable high-frequency signal transmission and extending the working life of the probes.
Implementation Method 1
a flexible membrane which comprises a first face and a second and opposite face, the first portion of the flexible membrane being arranged on at least one support and comprising a plurality of strips extending between a proximal end and a distal end
Implementation Method 2
contact elements of a testing head of the probe card also have an end portion abutting onto such end of the strips but onto an opposite face of the flexible membrane, in this way acting as damping support elements for the corresponding micro contact probes
Data Source
AI summary
A probe card for a testing apparatus of electronic devices comprises a testing head, which houses a plurality of contact elements extending along a longitudinal axis (H-H) between a first end portion and a second end portion, a support plate, onto which the first end portion is adapted to abut, and a flexible membrane which comprises a first face and a second and opposite face. Conveniently, the first portion of the flexible membrane is arranged on at least one support and comprises a plurality of strips extending between a proximal end and a distal end, the probe card further including a plurality of micro contact probes comprising a body extending along the longitudinal axis (H-H) between a first end portion and a second end portion, the second end portion of each contact element abutting onto the first face of the flexible membrane at the distal end of a respective strip, and the first end portion of each micro contact probe abutting onto the second face of the flexible membrane at a respective contact element, the flexible membrane being electrically connected to the support plate through a second portion thereof, the second end portion of the micro contact probes being apt to contact the contact pads of a device to be tested, wherein the at least one support is provided with a plurality of guide holes for the housing of the plurality of micro contact probes.