Hybrid Optical-Electrical PCB Interconnects
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Solution Overview
Problem
Conventional high-speed printed circuit boards (PCBs) face limitations in achieving high bandwidth and low signal loss due to the high dielectric loss of materials like FR4, making it difficult to support increasing signal speeds and interconnection densities, especially as IC technologies evolve, and existing low-loss materials are costly and incompatible with standard manufacturing processes.
Innovation Solution
The integration of optical and electrical signals in a hybrid interconnect system using open tunnels or trenches in the PCB substrate, where optical signals are transmitted through air or low-loss materials, reducing dielectric loss and increasing bandwidth, while maintaining compatibility with conventional manufacturing processes and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional FR4 dielectric material is used in PCB, then manufacturing cost is low and manufacturing process is mature, but dielectric loss is high which limits bandwidth
Solution Approach 1:
The patent divides the PCB into multiple layers with different dielectric materials. Low-loss dielectric material is used specifically in the signal transmission path (between signal traces), while standard FR4 material is used in other layers for cost-effective manufacturing. This segmentation allows the system to achieve low dielectric loss where needed while maintaining overall manufacturing efficiency and cost-effectiveness.
2Speed
If signal speed is increased, then data rate is improved, but signal dispersion increases due to fixed dielectric material
Solution Approach 1:
The patent changes the dielectric parameter (loss tangent) in the signal transmission path by using low-loss dielectric material specifically between the signal traces. This parameter change reduces dielectric loss and signal dispersion, enabling higher signal speeds to be achieved without proportional increase in signal degradation. The low-loss material has a lower loss tangent that compensates for the higher frequency operation.
3Loss of energy
If low-loss dielectric material is used, then bandwidth is increased, but manufacturing cost increases and process compatibility is reduced
Solution Approach 1:
The patent applies low-loss dielectric material locally only in the critical signal transmission regions where dielectric loss directly impacts bandwidth performance. Other non-critical areas of the PCB continue to use standard FR4 material. This local quality approach ensures that the expensive low-loss material is used only where it provides the necessary performance benefit, while maintaining cost-effective manufacturing for the overall board.
4Productivity
If number of interconnections is increased, then integration level is improved, but cross talk increases due to conventional dielectric material
Solution Approach 1:
The patent changes the dielectric parameter (loss tangent) in the regions between adjacent signal traces to a lower value using low-loss dielectric material. This parameter change reduces the coupling between adjacent signals, thereby reducing cross-talk. The lower loss tangent material provides better electrical isolation between neighboring interconnections, enabling higher interconnection density without proportional increase in cross-talk interference.
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 achieves exponentially increased data rates, exceeding terabit per second interconnection speeds, reducing signal dispersion and power loss, and is cost-effective by utilizing standard dielectric materials and manufacturing techniques.
Implementation Method 1
optical signals are transmitted through air or low-loss materials
Implementation Method 2
reducing dielectric loss and increasing bandwidth
Data Source
AI summary
Disclosed herein is a technique for increasing bandwidth for super high speed interconnects. The invention combines an electrical signal with an optical signal to provide a bandwidth greater than is possible with each individual signal.