Probe Card Test Probes with Grounded Wire Winding for Noise Reduction
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Solution Overview
Problem
Traditional cantilever probe cards experience noise interference from electromagnetic interference during high-frequency tests, leading to inconsistent results and reduced productivity.
Innovation Solution
The probe card assembly features test probes with a conductive wire winding on their middle sections, connected to the grounding end, which reduces inductance and noise by ensuring a specific length and diameter relationship (L1≧L2+3.14 D1) to effectively transmit high-frequency signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional cantilever probe card with closely arranged test probes is used, then the device structure is simple and easy to manufacture, but electromagnetic interference between probes causes noise and reduces measurement precision
Solution Approach 1:
The patent introduces an intermediate shielding structure (conductive shielding layer or ground probe) between adjacent signal probes. This intermediary element acts as a barrier to electromagnetic fields, preventing direct interference between neighboring probes while maintaining the overall probe card structure. The shielding layer is connected to ground potential, effectively diverting electromagnetic noise away from signal paths.
Solution Approach 2:
The patent modifies key geometric parameters of the probe structure, specifically increasing the spacing between adjacent probes or adjusting the probe tip dimensions and orientation. By changing these physical parameters, the electromagnetic coupling between probes is reduced, thereby decreasing noise and improving measurement precision without requiring complete structural redesign.
2Productivity
If test probes are closely arranged to increase testing capacity, then productivity is improved, but electromagnetic interference increases causing noise and requiring repeated tests
Solution Approach 1:
Ground probes or shielding structures are positioned between closely spaced signal probes to act as electromagnetic barriers. These intermediaries block or redirect electromagnetic fields, preventing noise coupling between adjacent signal probes while allowing the probes to remain closely arranged for high productivity.
Solution Approach 2:
The patent introduces ground probes that are maintained at ground potential between signal probes. By creating equipotential regions (grounded zones) between adjacent signal paths, electromagnetic interference is minimized as the ground probes provide a reference potential that stabilizes the electromagnetic environment and reduces noise coupling.
3Reliability
If traditional probe card structure is used for high-frequency testing, then device complexity is low, but signal transmission stability deteriorates due to increased noise and inductance
Solution Approach 1:
Conductive shielding layers or ground probes are introduced as intermediary elements between signal paths. These structures provide electromagnetic shielding and reduce inductance by providing alternative current paths and stabilizing the electromagnetic field distribution, thereby improving signal transmission stability for high-frequency applications.
Solution Approach 2:
The probe card structure employs composite construction combining signal-conductive materials (for probe tips and signal paths) with electromagnetic shielding materials (conductive shielding layers). This composite approach integrates both signal transmission functionality and noise protection within a unified structure, enhancing reliability without proportionally increasing complexity.
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 enhances the accuracy and reduces noise in high-frequency tests, stabilizing signal transmission and reducing inductance between power and grounding probes.
Implementation Method 1
The conductive wire winding on the test probe has a length L1 and a wound part of the middle section has a length L2 while the insulation layer at the middle section of the test probe has an outer diameter D1, wherein for the probe card assembly to smoothly transmit high-frequency signals, it is preferred that L1, L2 and D1 are in a relation shown by the formula below: L1≧L2+3.14 D1
Implementation Method 2
at least one of the test probes other than the grounding probe has an outer surface of its middle section wound by at least one conductive wire whose two ends are connected with a grounding end of the main body of the probe card assembly
Data Source
AI summary
Disclosed are a probe card assembly and test probes used therein. The probe card assembly includes a main body, a probe base provided at a center of the main body, and a plurality of test probes connecting the main body and the probe base. Therein, each of the test probes has a tip extending out from the probe base for contacting and testing a wafer. The test probes include at least one power probe, at least one grounding probe and a plurality of signal probes, wherein each of the test probes has a middle section between the main body and contains therein a core that is wrapped by an insulation layer.