Fine Pitch Probe Card Interface Impedance Control
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Solution Overview
Problem
Current probe cards face challenges in interfacing fine pitch integrated circuit devices without sacrificing signal quality or efficiency, particularly due to the adverse effects of long transmission paths on signal distortion and noise susceptibility in high-frequency signaling.
Innovation Solution
A low-cost fine pitch interface is developed, incorporating an impedance control component with a dielectric material and a power/ground component formed from flexible PCB materials with copper-filled vias, which reduces signal reflections and noise by controlling impedance and shortening power transmission paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a low-cost space transformer made of wires is used to interface probe head pins with PCB traces, then manufacturing cost is reduced, but transmission path length increases causing signal distortion and impedance discontinuities in high-frequency signaling
Solution Approach 1:
The patent introduces a custom PCB trace pattern as an intermediary element between the probe head pins and the main PCB traces. This intermediate trace layer provides controlled impedance pathways that are optimally lengthed to match the probe head pin spacing, thereby reducing impedance discontinuities and signal reflections while maintaining cost-effectiveness through standard PCB fabrication processes
Solution Approach 2:
The patent modifies the physical parameters of the transmission path by creating custom trace patterns with specific widths, lengths, and geometries on the intermediate PCB layer. These parameter adjustments are designed to match the impedance characteristics of the probe head pins, thereby minimizing signal distortion and reflections without requiring expensive multilayer ceramic space transformers
2Ease of manufacture
If longer ground paths are used to connect to external power supply, then power delivery is simplified, but inductance increases causing radiation and susceptibility to external noise and interference
Solution Approach 1:
The patent segments the ground connection path into multiple localized ground pads distributed across the PCB, each connected to nearby power/ground pins on the probe head. This segmentation creates multiple short ground paths instead of a single long path, thereby reducing overall inductance and minimizing noise susceptibility while maintaining simple power delivery architecture
Solution Approach 2:
The patent transitions from a planar ground path approach to a three-dimensional ground reference system by incorporating ground pads at multiple vertical levels through vias. This vertical stacking of ground references reduces the effective inductance of ground paths and provides better electromagnetic shielding, thereby reducing noise susceptibility without complicating the power delivery system
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 improves signal quality and reduces noise interference, enabling reliable testing of fine pitch IC devices without increasing costs.
Implementation Method 1
an impedance control component with a dielectric material... which reduces signal reflections and noise by controlling impedance
Implementation Method 2
a power/ground component formed from flexible PCB materials with copper-filled vias
Data Source
AI summary
A probe card interface for interfacing a probe head with a first circuit. The probe card interface includes an impedance control element to interface a first set of pins of the probe head with the first circuit. The impedance control element is further configured to control the impedance of the first set of pins. The probe card interface includes a conductive plane to interface a second set of pins of the probe head with the first circuit. The conductive plane is further coupled to provide at least one of power or ground to the second set of pins.