Cable Shield Termination Using Ferrule and Sock for EMI Control
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Solution Overview
Problem
Current cable and harness manufacturing techniques using drain-wires (pig tails) contribute to Electromagnetic Interference (EMI) outages due to higher impedance and larger loop areas, reducing the effectiveness of cable shielding against RF susceptibility and increasing EMI emissions.
Innovation Solution
Electrical connections of individual cable shields are made within the harness design without separate drain-wires, utilizing a ferrule and conductive sock to directly connect the shields to the backshell, eliminating the need for drain-wires and reducing impedance and loop area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If drain-wires (pig tails) are used to terminate cable shields, then the shielding structure is simpler to implement, but the impedance increases and loop area enlarges, reducing EMI protection effectiveness
Solution Approach 1:
The patent extracts and eliminates the drain-wire (pig tail) component from the shield termination system. By removing this intermediate element, the shield is directly connected to the connector backshell, reducing impedance and loop area while maintaining manufacturing simplicity through the integrated ferrule and sock structure
Solution Approach 2:
The patent merges the shield termination function directly into the connector backshell structure. The ferrule and conductive sock are integrated with the backshell, combining multiple functions (shield termination, grounding, and structural support) into a single unified assembly, eliminating the need for separate drain-wires
2Ease of operation
If drain-wires (pig tails) are used to terminate cable shields, then the assembly process is more traditional and familiar, but the loop area increases, increasing susceptibility to cross-coupling and EMI emissions
Solution Approach 1:
The drain-wire is extracted from the assembly process, eliminating the large loop area that causes cross-coupling susceptibility. The direct connection method maintains operational simplicity while significantly reducing the harmful electromagnetic loop area
3Ease of manufacture
If drain-wires (pig tails) are used to terminate cable shields, then the termination method is easier to implement, but the impedance increases, increasing EMI emissions
Solution Approach 1:
The shield termination is merged directly with the connector backshell through the ferrule and conductive sock integration. This eliminates the high-impedance drain-wire connection while maintaining ease of manufacture through the unified structure that requires no additional termination steps
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 improves EMI protection, reduces susceptibility to cross-coupling, enhances reliability, and simplifies assembly by eliminating the use of drain-wires, leading to improved manufacturability and field performance.
Implementation Method 1
Electrical connections of individual cable shields are made within the harness design without separate drain-wires, utilizing a ferrule and conductive sock to directly connect the shields to the backshell
Data Source
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Figure 5
AI summary
A connector assembly or wiring unit that includes one or more wiring cables (102), each cable unit including one or more wires surrounded by a cable shield, a connector backshell (140), and a ferrule (120) disposed such that the one or more wires are arranged on an outer surface of the ferrule (120). In one embodiment, the connector assembly or wiring unit also includes a conductive shield sock electrically coupled to the connector backshell (140). The shield sock surrounds the ferrule (120) and is in electrical contact with the cable shield of each of the one or more wiring cables (102).