Optical Interconnects for Printed Wiring Boards
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Solution Overview
Problem
Current optical backplane interconnects face challenges in replacing copper interconnects due to high implementation costs and large component sizes, which hinder their adoption in high-density applications, especially in stacked printed wiring boards (PWBs) where space and alignment precision are critical.
Innovation Solution
The development of an electro-optical system comprising an optically transmissive substrate with lenses and opto-electronic devices that can be surface-mounted on PWBs, allowing for efficient optical data communication between stacked boards, using components like VCSELs and photodetectors flip-chip mounted on transparent substrates, with electrical connections for alignment tolerances compatible with existing manufacturing infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional copper-based interconnects are used for high-speed data transmission between PWBs, then signal transmission capability is maintained, but the system suffers from increased EMI, routing complexity, and physical size constraints
Solution Approach 1:
The patent replaces copper-based electrical interconnects with optical interconnects using VCSELs, photodetectors, and optical waveguides. This substitution eliminates electromagnetic interference (EMI) inherent in copper-based systems while maintaining high-speed data transmission capabilities. The optical system uses light instead of electrical signals to transmit data between stacked PWBs, fundamentally resolving the EMI issue.
2Manufacturing precision
If optical interconnect components are implemented with high precision alignment requirements, then optical coupling efficiency is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent transitions from planar optical coupling to three-dimensional vertical stacking with optical through-silicon vias (TSVs). By utilizing the vertical dimension, the system achieves optical interconnect between stacked PWBs without requiring complex lateral alignment. The optical path is established through vertically aligned holes in the substrate, simplifying the manufacturing process while maintaining coupling efficiency.
Solution Approach 2:
The patent introduces optical bonding layers and alignment marks as intermediary elements to facilitate precise optical coupling. These intermediaries provide reference points and coupling media that simplify the alignment process during manufacturing, reducing the direct complexity of achieving precise optical alignment between components.
3Area of moving object
If compact optical components are used to reduce physical size, then space efficiency in stacked PWBs is improved, but component integration density and routing complexity increase
Solution Approach 1:
The patent divides the optical interconnect system into modular segments: VCSEL arrays on one PWB, optical waveguides through the substrate, and photodetector arrays on the opposing PWB. This segmentation allows each component to be optimized independently and simplifies the overall routing complexity by creating a systematic approach to optical signal distribution across multiple stacked boards.
Solution Approach 2:
The patent implements universal optical interconnect structures that can handle multiple data channels through a single optical path infrastructure. The optical waveguide system and TSV architecture provide a multi-functional platform that supports high-density data transmission without proportionally increasing routing complexity, as the same structural elements serve multiple signaling functions.
4Weight of moving object
If heavy electrical cabling is replaced with optical interconnects, then weight reduction is achieved, but implementation cost and component size initially increase
Solution Approach 1:
The patent employs thin-film optical waveguides and bonding layers integrated directly into the PWB substrate structure. These thin-film structures replace bulky traditional optical components and heavy electrical cabling, achieving weight reduction while maintaining compact form factor. The optical interconnect structure becomes part of the board itself rather than adding separate heavy components.
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 solution enables efficient, lightweight, and compact optical data communication between PWBs, reducing the need for heavy electrical cabling and allowing for easy replacement of defective components, while maintaining compatibility with existing backplane formats and manufacturing processes.
Implementation Method 1
a lens disposed on a first side of the substrate; at least one of an optical emitter and optical receiver disposed on a second side of the substrate, substantially in axis with the lens
Data Source
AI summary
A component system and method is described that is made of components for transmitting, routing and receiving “in-air” optical signals for placement on printed wiring boards (PWBs). The transmitters are components including a light source attached to a transparent substrate and aligned to a coupling lens. The transparent substrate can contain circuitry for controlling the light source, or the circuitry could be attached to the transparent substrate. The receivers include a light detector attached to a transparent substrate with circuitry for converting optical signals to electrical circuitry (integrated onto the transparent substrate or separately attached). The routing components include a lens for coupling light into an optical waveguide, an optical waveguide and, optionally, a second lens for coupling light from the optical waveguide. The component system allows in-air optical communication between PWBs, without requiring traditional connections and harnesses between the PWBs, thus increasing their reliability and throughput.