Vertical Probe Card Impedance Matching via Flexible Probes
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Solution Overview
Problem
Existing vertical-type probe cards fail to maintain characteristic impedance for high-frequency signal transmission without damaging semiconductor wafers, due to impedance mismatch and rigid probe structures that can cause damage to test contacts and internal circuits.
Innovation Solution
A vertical-type probe card design featuring a circuit board with parallel signal and grounding circuits, a probe assembly with flexible signal and grounding probes, and a compensation probe to maintain impedance and prevent stress on the test sample, using a conducting layer and guide plates to ensure reliable high-frequency signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid probe structures are used to maintain structural stability, then the probe card can maintain characteristic impedance for high-frequency signal transmission, but the probes may damage the test contacts on the test wafer or destruct internal circuit devices
Solution Approach 1:
The patent makes the probe structure dynamic by allowing the probe to flexibly bend through a receiving chamber defined between upper and lower guide plates. This dynamic capability enables the probe to adapt to contact variations without damaging the test wafer, while the overall structure maintains characteristic impedance for high-frequency signal transmission.
Solution Approach 2:
The patent employs a flexible probe structure that can bend within the receiving chamber formed by the guide plates. This flexible design allows the probe to conform to the test contact surface without applying excessive force, preventing damage to delicate test contacts and internal circuit devices while maintaining electrical connection integrity.
2Object-affected harmful factors
If flexible probe structures are used to prevent damage to test samples, then the probes can adapt to contact variations, but the characteristic impedance for high-frequency signal transmission cannot be maintained
Solution Approach 1:
The patent introduces guide plates as intermediary structures that define a receiving chamber. These guide plates serve as mediators between the flexible probe and the rigid circuit board, allowing the probe to flexibly bend while the guide plates maintain the overall structural integrity and characteristic impedance required for high-frequency signal transmission.
Solution Approach 2:
The patent segments the probe structure into distinct functional zones: the flexible probe portion that can bend within the receiving chamber, the guide plates that provide structural support and maintain impedance, and the connection points to the circuit board. This segmentation allows each component to perform its specific function without compromising the overall system performance.
3Device complexity
If individual conducting probes without outer shielding are used to simplify the probe structure, then the probe card design becomes simpler, but parasitic capacitors induce dielectric loss of high-frequency signals
Solution Approach 1:
The patent uses the guide plates as intermediary shielding structures that surround the flexible probe within the receiving chamber. These guide plates act as electromagnetic shields without requiring complex outer shielding on each individual probe, thus maintaining signal integrity and reducing dielectric loss while keeping the overall structure relatively simple.
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 achieves excellent impedance matching and low return loss, with the signal probes and grounding probes being flexible to prevent damage to the test sample, allowing for high-quality high-frequency signal transmission up to GHz frequencies.
Implementation Method 1
maintain the characteristic impedance for the transmission of the applied high-frequency test signal
Implementation Method 2
accompanied with the grounded current flow through the grounding circuits and the compensation probe
Implementation Method 3
The signal probe and the grounding probe are flexible in the receiving chamber
Data Source
AI summary
A vertical-type probe card includes a circuit board, which has signal circuits and grounding circuits arranged in such a manner that each signal circuit is disposed in parallel and adjacent to one grounding circuit and kept a predetermined distance from the grounding circuit, and a probe assembly, which is arranged at the bottom side of the circuit board and has an upper guide plate, a lower guide plate, a conducting layer provided on the lower guide plate, a plurality of signal probes respectively electrically connected to the signal circuits and adjacent to a plurality of compensation probes, and at least one grounding probe electrically connected to the grounding circuits in a manner that the signal, compensation and grounding probes are vertically inserted through the upper and lower guide plates, and the conducting layer is conducted with the compensation probe and the grounding probe while electrically insulated to the signal probe.