Wiring Substrate Layout Using Cable Links for Low-Loss Signals
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Solution Overview
Problem
Existing wiring substrates experience increased signal transmission loss and quality deterioration due to higher processing frequencies, with conventional solutions either increasing power consumption or substrate size, and struggling to effectively mitigate impedance mismatching and crosstalk.
Innovation Solution
A wiring substrate design featuring a first connector on one surface connected to a backplane, an opening portion for a cable, an integrated circuit on the opposite surface, and a second connector on the back surface connected via through holes to the cable, utilizing cables with lower transmission loss instead of substrate wiring, and air guiding plates to manage cooling air efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If substrate wiring is used for signal transmission, then the substrate structure is simple, but transmission loss increases and signal quality deteriorates at high processing frequencies
Solution Approach 1:
The substrate is divided into a first substrate and a second substrate that are bonded together, with the cable passing through an opening in the first substrate and connecting to a connector on the second substrate. This segmentation allows the use of cable transmission instead of substrate wiring, reducing transmission loss while maintaining a manageable structure.
Solution Approach 2:
A cable is introduced as an intermediary element to transmit signals between the connector on the second substrate and the integrated circuit on the first substrate. This cable acts as a mediator that provides lower transmission loss compared to substrate wiring at high frequencies, while connectors and through-holes facilitate the connection.
2Reliability
If cables are used instead of substrate wiring, then transmission loss is reduced, but the substrate requires additional openings and connectors increasing complexity
Solution Approach 1:
The opening for cable passage and the connector mounting area are integrated into a unified structure where the connector is mounted on the second substrate and electrically connected via through-holes. This merging reduces the number of separate components and simplifies the overall assembly process.
Solution Approach 2:
The cable connection is moved from a planar substrate wiring approach to a three-dimensional configuration where the cable passes through the substrate thickness direction. This dimensional change allows the cable to bypass the substrate wiring layer, reducing electromagnetic interference and transmission loss while the connector provides the necessary electrical interface.
3Ease of operation
If through-holes are used to connect connectors to integrated circuits, then cable connection is enabled, but through-hole crosstalk may occur
Solution Approach 1:
The signal transmission function is extracted from the substrate wiring and moved to the cable that passes through the opening. The through-holes are then used only for mechanical connection and electrical grounding, separating the high-frequency signal path from the potential crosstalk sources in the substrate layers.
Solution Approach 2:
The through-holes are designed as simple, inexpensive connection points that provide mechanical support and electrical reference planes, while the expensive and critical signal transmission function is handled by the dedicated cable with controlled impedance, which can be replaced or upgraded independently.
Data Source
AI summary
A wiring substrate is connected to a backplane, and includes: a first connector that is mounted on one surface of the wiring substrate and is connected to the backplane; an opening portion that is formed in the one surface on a side opposite to a side connected to the backplane of the first connector, and through which a cable having one end connected to the first connector is passed; an integrated circuit that is mounted on the one surface on a side opposite to a side on which the first connector is present relative to the opening portion; and a second connector that is mounted on the other surface on a side opposite to the one surface in the vicinity of the integrated circuit on the side opposite to the side on which the first connector is present relative to the opening portion, is connected to the integrated circuit via a through hole penetrating the wiring substrate, and is connected to the other end of the cable.