Embedded Optical Waveguides in Flexible PCBs for Low-Loss Signaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional flexible printed circuit boards (FPCBs) face issues with high signal loss and reduced transmission distance due to copper wire limitations, and existing optical waveguide designs increase board thickness and limit stackable layers, necessitating improvements in waveguide density and thickness reduction.
Innovation Solution
The integration of optical waveguides within flexible layers through a build-up process, allowing simultaneous formation of reflective structures with electrical circuits, reducing thickness and complexity, and enhancing alignment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical waveguides are mounted on the surface of flexible layer, then optical signal transmission is achieved, but the thickness of entire flexible printed circuit board is substantially increased
Solution Approach 1:
The optical waveguide structure is embedded within the flexible insulation layer, nesting the optical transmission function inside the existing flexible layer structure rather than adding it as a separate external component, thereby achieving optical transmission without substantially increasing overall thickness
Solution Approach 2:
The invention transitions from surface-mounted optical components (2D plane) to embedded optical waveguides within the flexible layer (3D volume utilization), changing the dimensional arrangement to achieve compact integration
2Adaptability or versatility
If dies are mounted on flexible layer, then optoelectronic units are integrated, but layer build-up process cannot be performed, reducing the number of stackable waveguide layers
Solution Approach 1:
The optical waveguide structures are formed within the flexible insulation layer during the build-up process before final assembly, performing the waveguide creation action in advance while the layer structure is still being constructed, enabling subsequent stacking operations
Solution Approach 2:
The invention merges the waveguide formation process with the flexible PCB build-up process, combining what were previously separate manufacturing sequences into a unified process flow that enables both optoelectronic integration and multi-layer stacking
3Reliability
If reflective components are mounted separately on flexible layer, then optical reflection is achieved, but process complexity and steps are increased
Solution Approach 1:
The reflective structures are formed simultaneously with the circuit patterns during the same manufacturing process step, merging two separate fabrication operations into one, thereby reducing process complexity and steps while ensuring precise alignment
Solution Approach 2:
The reflective structures are formed as part of the circuit pattern fabrication process, performing the reflection function preparation in advance during the standard PCB manufacturing sequence rather than as a separate post-processing step
4Length of stationary object
If optical waveguides are embedded in flexible layers through build-up process, then thickness is reduced, but manufacturing precision requirements are increased
Solution Approach 1:
The optical waveguide structures are formed during the build-up process with predetermined positions and orientations, establishing precise alignment references in advance that guide subsequent assembly steps and ensure accurate positioning of optoelectronic 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 approach reduces signal loss and thickness while increasing waveguide density, improving signal quality and transmission efficiency in high-speed applications.
Implementation Method 1
an optical waveguide structure stacked with the flexible insulation layer for transmitting optical signal
Implementation Method 2
a first metal bump adjacent to the optical waveguide structure and in optical alignment with the first optoelectronic unit to provide a reflection plane for optical signal, a second metal bump adjacent to the optical waveguide structure and in optical alignment with the second optoelectronic unit to provide a reflection plane for optical signal
Implementation Method 3
a first optoelectronic unit embedded in the photoelectric transmission unit and configured to convert electrical signal into optical signal
Implementation Method 4
a second optoelectronic unit embedded in the photoelectric transmission unit and configured to convert optical signal into electrical signal
Data Source
AI summary
A flexible printed circuit board with embedded optical waveguide structure, including a photoelectric transmission unit, wherein the photoelectric transmission unit includes a flexible insulation layer, a first optoelectronic unit and a second optoelectronic unit embedded in the photoelectric transmission unit, at least one redistribution layer having at least one conductive structure stacked with the flexible insulation layer and electrically connected with the first optoelectronic unit and second optoelectronic unit, an optical waveguide structure stacked with the flexible insulation layer, a first metal bump and a second metal bump adjacent to the optical waveguide structure and in optical alignment respectively with the first optoelectronic unit and the second optoelectronic unit to provide reflection planes for optical signal, wherein first metal bump and second metal bump are solid structures made of the same material as the one of redistribution layer.