Cable Shield Tunnel for Signal Integrity
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Solution Overview
Problem
The signal integrity of signal conductors is diminished at the transition area between the cable core and the circuit card due to the lack of effective shielding in electrical devices with differential pairs of signal conductors.
Innovation Solution
A cable shield tunnel is provided, comprising a ground bus and a floor shim coupled to the circuit card, forming a tunnel to receive the cable end, with the ground bus extending along the sides and the floor shim positioned between the cable and the card to enhance electrical shielding and impedance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cable jacket, shield layer, and insulation are removed to expose signal conductors for mechanical and electrical coupling to contacts, then the signal conductors can be connected to the circuit card, but signal integrity is diminished at the transition area due to lack of effective shielding
Solution Approach 1:
A cable shield tunnel structure is introduced as an intermediary component between the cable and circuit card. The tunnel includes a ground bus with end wall and side walls, plus a floor shim positioned between the cable and circuit card, creating an enclosed tunnel that receives the cable end. This intermediary structure provides continuous shielding at the transition area where signal conductors connect to contacts, preventing signal integrity degradation while allowing mechanical and electrical coupling to proceed.
2Reliability
If a traditional shielding structure is used at the cable termination, then shielding is provided, but the structure becomes complex and difficult to manufacture
Solution Approach 1:
The shielding structure is segmented into two separate components: a ground bus assembly comprising an end wall and side walls, and a floor shim positioned between the cable and circuit card. These segmented parts are easier to manufacture individually and assemble than a monolithic shielding structure, while collectively forming an effective enclosed tunnel that maintains shielding effectiveness at the cable termination.
Solution Approach 2:
The shielding approach changes from traditional continuous shielding to a segmented tunnel structure with specific geometric parameters. The ground bus includes an end wall extending along the first end and side walls extending from the end wall, creating a tunnel with defined dimensions. The floor shim has a thickness selected based on tunnel height and cable height parameters, optimizing the shielding effectiveness while simplifying manufacturing.
Data Source
AI summary
A cable shield tunnel for an electrical device includes a ground bus and a floor shim, discrete from the ground bus, and coupled to a circuit card and forming a cable tunnel that receives an end of a cable. The ground bus includes an end wall extending along a first end of the cable tunnel, a first side wall extending from the end wall along a first side of the cable tunnel, and a second side wall extending from the end wall along a second side of the cable tunnel opposite the first side. The first and second side walls are configured to be coupled to the circuit card. The floor shim is provided at a second end of the cable tunnel opposite the first end and is positioned between the cable and the circuit card.