Optical PCB Waveguide Obtuse Angle Curvature Design
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Solution Overview
Problem
Optical printed circuit boards (PCBs) face challenges in light transmission efficiency and structural integrity due to the need for right-angle bends in optical waveguides, which lead to increased thickness and potential breakage from high tension, as well as difficulties in light alignment with small sectional areas.
Innovation Solution
The implementation of an optical PCB with thermosetting insulating materials surrounding the optical waveguide to maintain an obtuse angle curvature, reducing tension and increasing the exposed aperture area, while using a multi-channel or multi-layer structure with a core layer and clad layers to enhance light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the optical wave guide is bent at a right angle to change the optical path, then the optical path changing function is achieved, but the optical wave guide is easily broken due to high tension and the thickness of the optical PCB is increased
Solution Approach 1:
The patent applies curvature by changing the bending angle of the optical wave guide from a right angle (90 degrees) to an obtuse angle (greater than 90 degrees). This curved path design reduces the tensile stress concentrated at sharp bends, preventing wave guide breakage while still achieving the optical path changing function. The smoother curvature distributes the mechanical stress more evenly along the wave guide structure.
Solution Approach 2:
The patent changes the geometric parameter of the bending angle from 90 degrees to an obtuse angle (e.g., 100-150 degrees). This parameter modification directly reduces the bending tension and associated light loss, while also decreasing the thickness requirement of the optical PCB. The angle parameter is optimized to balance optical performance, mechanical reliability, and structural compactness.
2Length of stationary object
If the thickness of the optical wave guide is reduced to reduce the thickness of the optical PCB, then the PCB thickness is reduced, but the optical wave guide must be bent with a smaller radius of curvature which increases breakage risk
Solution Approach 1:
By using an obtuse angle bend instead of a right angle, the effective bending radius is increased for a given PCB thickness reduction. This larger effective radius reduces the curvature stress on thin wave guides, enabling thickness reduction without proportionally increasing breakage risk.
Solution Approach 2:
The patent transitions from a two-dimensional planar bend to a three-dimensional obtuse angle configuration. This dimensional change allows the optical path to change direction while maintaining a larger bending radius, thus reducing stress on thin wave guides and enabling thinner PCB designs with improved reliability.
3Length of stationary object
If the optical wave guide has a small sectional area, then the thickness of the optical PCB is reduced, but light alignment becomes difficult
Solution Approach 1:
The obtuse angle configuration creates a more favorable geometric relationship between the wave guide and the optical components. The curved path allows for better spatial arrangement and larger effective alignment targets, making light alignment easier even when the wave guide has a small cross-sectional area and the PCB is thin.
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 configuration reduces the risk of waveguide breakage, allows for easier light alignment, and enhances the stability and reliability of the optical PCB by maintaining the obtuse angle and minimizing bending loss.
Implementation Method 1
The first and second optical path changing parts include thermosetting insulating materials surrounding the optical wave guide to keep the optical wave guide at the obtuse angle
Implementation Method 2
The core layer includes a material having a refractive index higher than a refractive index of a material for the clad layer
Data Source
Figure 1~5
Figure 6~10
Figure 11
AI summary
An optical printed circuit board according to the embodiment includes an insulating layer; an optical wave guide buried in the insulating layer to transmit an optical signal; and an optical path changing part provided on at least one end of the optical wave guide to change a transmission path of the optical signal defined by the optical wave guide such that the transmission path has a predetermined curvature.