Relay Substrate Layout for Shielded Connector Cable Impedance Control
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Solution Overview
Problem
Conventional connector cables that connect a connector and a shielded cable via a relay substrate face issues with increased impedance and short circuits when the braided shield of the coaxial cable is removed to expose the core wire and intermediate insulator, as extending the ground pattern to address impedance increases risks short-circuiting with the core wire.
Innovation Solution
A connector cable design where the ground conductor layer on the relay substrate is arranged directly under the part where the shield member is removed, covered with an insulating member to prevent short circuits and impedance increases, allowing direct soldering connection between the connector and inner conductor without bending the inner conductor, and featuring a resist-coated insulating member to maintain insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ground pattern is extended to directly under the exposed part where the braided shield is removed, then the impedance increase is reduced, but the ground pattern may be short-circuited with the core wire soldered to the adjacent signal pattern
Solution Approach 1:
An insulating member is introduced as an intermediary between the ground conductor layer and the exposed inner conductor. This insulating member covers the ground conductor layer directly under the exposed inner conductor, preventing direct contact and potential short circuits while maintaining the ground reference for impedance control. The insulating member acts as a mediator that allows the ground pattern to extend close to the signal path without creating electrical contact.
Solution Approach 2:
The insulating member is applied selectively only in the specific region where the ground conductor layer is directly under the exposed inner conductor. This localized application provides insulation precisely where the short circuit risk exists, while allowing the ground pattern to maintain its impedance-matching function in other areas. The ground conductor layer remains exposed in regions where short circuit risk is minimal.
2Ease of operation
If the braided shield is removed to expose the core wire and intermediate insulator, then direct connection to the connector is enabled, but the impedance increases due to the exposed part being far from ground patterns
Solution Approach 1:
The insulating member serves as a mediator that enables the ground conductor layer to approach the exposed inner conductor closely for impedance control without causing short circuits. This allows the simplified direct connection structure to maintain proper impedance matching, combining the benefits of ease of connection with electrical precision.
Solution Approach 2:
The solution moves the grounding problem into a different dimensional space by using the insulating member to create vertical separation between the ground conductor layer and the inner conductor, while maintaining horizontal proximity. This dimensional approach allows the ground reference to be close to the signal path for impedance control without creating electrical contact.
Data Source
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AI summary
To prevent both increase in impedance and a short circuit, a connector cable 100 is configured such that a connector 10 and a shielded cable 20 are connected via a relay substrate 30. The shielded cable 20 includes at least an inner conductor 21, a dielectric 22 covering the inner conductor 21, and a shield member 23 covering the dielectric 22. The inner conductor 21 is connected to a contact 11 of the connector 10 at a part where the shield member 23 and the dielectric 22 are removed to expose the inner conductor 21. At least directly under a part where the shield member 23 is removed to expose the dielectric 22, a ground (GND) conductor layer 32 on a front surface of the relay substrate 30 is arranged. The GND conductor layer 32 on the front surface of the relay substrate 30, which is arranged directly under the part where the shield member 23 is removed, is covered with an insulating member 31.