Conductive Dome Probes for High Speed PCB Signal Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-density integrated circuits (ICs) with large pin counts pose challenges in signal routing on multilayer printed circuit boards (PCBs), leading to issues with signal integrity, increased surface area, layer count, and via-routed crosstalk due to conventional plated through-hole (PTH) technology.
Innovation Solution
The use of high-density interconnect (HDI) components such as microvias (μVias) and subcomposite vias, combined with strategic pin assignment and layout techniques, to reduce the number of PCB layers, minimize crosstalk, and enhance signal integrity by optimizing the placement of power and ground pins, and routing signals in a pyramidal escape profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plated through-hole (PTH) technology is used for signal routing, then signal routing is achieved, but signal integrity deteriorates and via-routed crosstalk increases
Solution Approach 1:
The patent divides the via structure into multiple segments: microvias for vertical interconnect and subcomposite vias for lateral routing. This segmentation allows signals to transition from conventional PTH to a hybrid structure that reduces crosstalk by separating the vertical penetration function from the lateral routing function, thereby improving signal integrity while reducing harmful via-routed crosstalk.
Solution Approach 2:
The patent applies different via structures in different locations: microvias are used where vertical interconnect is needed, subcomposite vias are used for lateral routing, and the combination creates localized optimized paths. This local quality approach ensures that each via structure performs its specific function optimally, reducing overall crosstalk while maintaining signal integrity.
2Ease of manufacture
If high-density interconnect (HDI) components are used, then manufacturing cost is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent transitions from conventional two-dimensional via routing to a three-dimensional hybrid structure combining microvias and subcomposite vias. This dimensional change allows signals to route vertically through microvias and laterally through subcomposite vias, reducing the need for multiple PTH vias and thereby reducing manufacturing cost while managing the increased precision requirements through structured implementation.
Solution Approach 2:
The patent nests the microvia structure within the subcomposite via structure, creating a hierarchical via system. The microvia is positioned at the bottom of the subcomposite via, allowing the combined structure to achieve complex routing functions while maintaining a compact footprint, thus reducing overall manufacturing cost despite the increased precision needed for the nested structure.
Data Source
AI summary
Methods and apparatus for accessing a high speed signal routed on a conductive trace on an internal layer of a printed circuit board (PCB) using high density interconnect (HDI technology) are provided. The conductive trace may be coupled to a microvia (μVia) having a conductive dome disposed above the outer layer pad of the μVia. In-circuit test (ICT) fixtures or high speed test probes may interface with the conductive dome to test the high speed signal with decreased reflection loss and other parasitic effects when compared to conventional test points utilizing plated through-hole (PTH) technology.