Dual-Layer Braided Shield for EMI Reduction and Crimp Integrity
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Solution Overview
Problem
Conventional braided metallic shields for electronic devices suffer from holes that allow electromagnetic radiation to penetrate, leading to interference and galvanic corrosion, and unraveling that weakens the crimp and reduces pull strength.
Innovation Solution
A dual-layer braided shield with an inner layer integrally formed with the outer layer and a support, reducing holes and preventing unraveling, achieved through a method involving a housing with a passage and end portion compression to secure the crimp band without nuts or bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solid metal support is crimped to the terminal end of the shield, then the shield is secured to the support, but the terminal end expands creating holes that allow electromagnetic radiation to penetrate
Solution Approach 1:
The shield is segmented into multiple layers (first braid layer and second braid layer) that are disposed at different radial positions. This segmentation allows the terminal end to be secured without requiring expansion that would create holes, as each layer provides independent shielding coverage.
Solution Approach 2:
The second braid layer is nested within or alongside the first braid layer, with both layers terminating at the same longitudinal position. This nested configuration allows the terminal end to be secured to the support without expanding the shield structure, maintaining continuous shielding coverage.
2Reliability
If the terminal end of the shield is expanded to secure it, then the shield is fixed in place, but the wires that form the braid begin to unravel causing additional holes
Solution Approach 1:
The shield structure is designed with the terminal end configuration predetermined, where the first and second braid layers are arranged to terminate at the same longitudinal position. This preliminary arrangement prevents unraveling during subsequent crimping or securing operations, as the wires are already in their final stable configuration.
Solution Approach 2:
The dual-layer structure provides a buffer against unraveling by distributing the mechanical stress of securing across multiple layers. The nested configuration of the braid layers cushiones against forces that would cause individual wires to unravel, maintaining braid integrity over time.
3Adaptability or versatility
If the shield wires are allowed to move freely, then the shield remains flexible, but the crimp to the metal support weakens over time reducing pull strength
Solution Approach 1:
The shield structure incorporates both flexible braid layers and a rigid terminal end configuration. The braid layers maintain flexibility for adaptability, while the terminally secured configuration provides dynamic stability that prevents progressive weakening of the crimp over time, balancing flexibility with long-term strength.
4Reliability
If the terminal end is secured with a metal support, then the shield is fixed, but galvanic corrosion occurs between the shield and the metal support
Solution Approach 1:
The shield structure uses an intermediate configuration where the braid layers are terminated and secured in a manner that minimizes direct galvanic contact between dissimilar metals. The nested dual-layer structure acts as an intermediary that reduces the electrochemical interaction between the shield and metal support, preventing galvanic corrosion while maintaining secure fixation.
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 blocks electromagnetic radiation and prevents corrosion, maintaining a strong and consistent crimp, thereby reducing interference and ensuring reliable signal transmission.
Implementation Method 1
A braided shield includes a housing having a dual-layer configuration... The inner layer and outer layer reduce the amount of electromagnetic radiation that leaks into or out of the housing
Implementation Method 2
compressing the end portion transverse to the longitudinal axis, and forcing the end portion into the passage to define the housing having an outer layer and an inner layer integrally formed with the outer layer
Data Source
AI summary
A braided shield includes a housing formed from a plurality of wires braided together and having a dual-layer configuration. The housing has an outer layer integrally formed with an inner layer. A support is at least partially disposed in the housing, and the inner layer is disposed between the support and the outer layer. The inner layer and outer layer reduce electromagnetic radiation leakage into/out of the housing by reducing the number of holes in the housing. Forming the braided shield includes providing the housing, which defines a longitudinal axis and a passage extending along the longitudinal axis. The housing has an end portion, and the end portion is compressed transverse to the longitudinal axis. The end portion is then forced into the passage. Accordingly, the braid shield reduces or eliminates electromagnetic radiation while providing a strong and consistent crimp with the support.