Conductive Plastic Shield for Signal Integrity
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Solution Overview
Problem
Shielded electrical cables with metal foil wrapping suffer from discontinuities and geometrical changes that affect signal integrity and bandwidth, leading to a trade-off between signal integrity, flexibility, and manufacturing costs, while also complicating the electrical connection of shield layers.
Innovation Solution
An electrical cable design featuring a conductive plastic shield layer with a molded body that surrounds a dielectric insulator, providing consistent signal integrity and flexibility, and allowing for electrical commoning of shield layers between conductor assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If metal foil is spiral wrapped around the insulation layer with overlay, then EMI/RFI leakage is prevented, but signal integrity deteriorates due to discontinuities and geometrical changes
Solution Approach 1:
The patent changes the fundamental parameter of shield layer construction from spiral-wrapped metal foil to a continuous molded plastic shield with embedded conductive elements. This parameter change eliminates the discontinuities and geometrical variations inherent in spiral wrapping, while maintaining EMI/RFI shielding effectiveness through the continuous conductive path provided by the molded shield structure.
Solution Approach 2:
The patent employs composite materials by integrating conductive elements (such as metal foil or conductive plastic) within a molded plastic shield layer. This composite structure combines the shielding effectiveness of conductive materials with the structural stability and continuity of molded plastic, eliminating the discontinuities associated with spiral wrapping while maintaining EMI/RFI protection.
2Loss of energy
If overlay length is increased to push attenuation outside operational bandwidth, then insertion loss improves, but cable rigidity and manufacturing time increase
Solution Approach 1:
The patent changes the shielding mechanism from relying on overlay length to relying on the continuous conductive path and geometry of the molded shield. This parameter change allows for reduced overlay length without compromising shielding effectiveness, thereby reducing cable rigidity and manufacturing time while maintaining low insertion loss across the operational bandwidth.
3Stability of the object's composition
If adhesive tape is used to hold the wrapped metal foil, then shield layer stability is improved, but electrical connection of shield layers becomes complicated
Solution Approach 1:
The patent merges the functions of shield layer stabilization and electrical connection by integrating conductive elements directly into the molded shield structure. This eliminates the need for separate adhesive tape layers and drain wires, as the molded shield itself provides both structural stability and continuous electrical pathways for connecting shield layers between conductor assemblies.
Solution Approach 2:
The patent extracts and eliminates the adhesive tape layer from the cable construction. By using a molded plastic shield with embedded conductive elements, the patent removes the need for tape to hold the shield in place, thereby simplifying the overall structure and eliminating the complexity of penetrating or removing tape to access the shield layer for electrical connections.
4Object-affected harmful factors
If metal foil and adhesive tape layers are wrapped over the foil, then shielding effectiveness is improved, but manufacturing time and material usage increase
Solution Approach 1:
The patent merges multiple separate layers (metal foil and adhesive tape) into a single integrated molded plastic shield structure with embedded conductive elements. This consolidation maintains shielding effectiveness while eliminating the sequential wrapping and adhesive application steps, thereby reducing manufacturing time and material usage.
Solution Approach 2:
The patent changes the manufacturing approach from sequential layering (foil wrapping then tape wrapping) to a single-step molded construction. This parameter change in the manufacturing process eliminates the time-consuming sequential operations while maintaining the shielding effectiveness through the integrated conductive structure.
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 design enhances signal performance by reducing insertion loss and EMI/RFI leakage, improves flexibility, and simplifies manufacturing by eliminating the need for adhesive tapes and reducing material usage and manufacturing time.
Implementation Method 1
The shield layer is formed of a conductive plastic material to provide electrical shielding for the at least one inner conductor
Implementation Method 2
The insulator is composed of a dielectric material
Data Source
AI summary
An electrical cable includes at least one conductor assembly. Each conductor assembly includes at least one inner conductor that extends along a length, an insulator, and a shield layer. The insulator engages and surrounds a surface of the at least one inner conductor. The insulator is composed of a dielectric material. The shield layer engages and surrounds an outer perimeter of the insulator. The shield layer is formed of a conductive plastic material to provide electrical shielding for the at least one inner conductor and flexibility.