Cable Ground Plane Coupling via Insulator Openings
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Solution Overview
Problem
Traditional cable-to-circuit board connections using the hotbar process result in impedance drops due to parasitic capacitance at the cable-to-pad interface, which affects the performance of information handling systems.
Innovation Solution
A system and method where a differential cable is mechanically contacted to a circuit board with conductive pads and a ground plane, using openings in the insulating material to directly couple the drain conductor to the ground plane, reducing capacitance and impedance discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hotbar process is used to mechanically contact cable conductors to circuit board pads, then the connection reliability is improved, but parasitic capacitance increases causing impedance drops
Solution Approach 1:
The patent extracts the drain conductor from the traditional pad contact approach and directly contacts it to the ground plane through openings in the insulating material. This removes the parasitic capacitance-generating interface between drain conductor and pad, while maintaining the reliable mechanical connection through the hotbar process.
Solution Approach 2:
The patent introduces openings in the insulating material as an intermediary structure that enables direct contact between the drain conductor and ground plane. This intermediary pathway eliminates the need for the drain conductor to contact the pad through dielectric material, thereby reducing parasitic capacitance while preserving connection reliability.
2Ease of manufacture
If traditional cable-to-pad interface is used, then mechanical connection is achieved, but impedance discontinuities occur affecting signal integrity
Solution Approach 1:
The patent transitions from a two-dimensional pad-based interface to a three-dimensional structure where the drain conductor contacts the ground plane through vertical openings in the insulating material. This dimensional change allows direct ground contact while maintaining mechanical connection, eliminating impedance discontinuities at the interface.
3Object-affected harmful factors
If dielectric material is used between drain conductor and ground plane, then insulation is provided, but capacitance increases reducing signal efficiency
Solution Approach 1:
The patent removes the dielectric material from between the drain conductor and ground plane by creating openings in the insulating material layer. This extraction eliminates the capacitance-forming dielectric interface while the surrounding insulating material structure continues to provide necessary insulation and mechanical support.
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 approach reduces parasitic capacitance and impedance drops, enhancing signal integrity and efficiency in information handling systems by minimizing the use of dielectric material and allowing direct contact between conductors and the ground plane.
Implementation Method 1
impedance drops due to parasitic capacitance at the cable-to-pad interface
Data Source
AI summary
A system may include a circuit board comprising a plurality of electrically-conductive layers separated and supported by layers of insulating material laminated together, wherein the plurality of electrically-conductive layers comprises a ground plane and the layers of insulating material comprise a surface layer having one or more openings through which the ground plane is exposed through the one or more openings. The system may also include a plurality of electrically-conductive pads formed on a surface of the surface layer and a cable comprising a first signal conductor mechanically contacted to a first pad of the plurality of electrically-conductive pads and a first drain conductor mechanically contacted to the ground plane through the one or more openings.