Opto-Electric Hybrid Board Alignment Marks for Shrinkage Compensation
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Solution Overview
Problem
The accuracy of alignment between a light receiving element and an optical path conversion mirror in optical waveguide devices is compromised due to shrinkage of the opto-electric hybrid board during production, leading to reduced positional accuracy and reliability of optical connections.
Innovation Solution
Incorporating alignment marks made of the same material as the optical waveguide, disposed at both outer sides of the mounting region in the width direction, which allows for calculation and consideration of shrinkage, ensuring accurate alignment by maintaining a sufficient distance and visibility from the thickness direction, and optionally using dummy mirrors or cores for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If alignment is based on a single alignment groove, then the structure is simple, but the alignment accuracy deteriorates due to board shrinkage
Solution Approach 1:
The alignment system is segmented from a single alignment groove into multiple alignment marks (first alignment mark and second alignment mark) positioned at different locations. This segmentation allows independent measurement of shrinkage at different positions, enabling calculation of shrinkage ratios that account for non-uniform board contraction, thereby maintaining high alignment accuracy despite board shrinkage during manufacturing.
2Ease of operation
If alignment marks are placed close to the mirror, then the alignment process is simplified, but the optical element may overlap with the alignment mark
Solution Approach 1:
The alignment marks are positioned in the width direction (lateral dimension) rather than being placed directly adjacent to the mirror in the optical path. By utilizing the width direction for mark placement and specifying that the optical element does not overlap with the marks when projected in the thickness direction, the solution separates the alignment function from the optical function spatially, preventing overlap while maintaining alignment effectiveness.
3Ease of manufacture
If the opto-electric hybrid board shrinks during heating, then the manufacturing process is standard, but the distance between alignment groove and mirror varies greatly
Solution Approach 1:
The system incorporates feedback through measuring the actual distances between the first alignment mark and the mirror, and between the second alignment mark and the mirror, after board shrinkage occurs. These measurements provide feedback on the shrinkage that has taken place, which is then used to calculate the shrinkage ratio and adjust the alignment process accordingly, compensating for the dimensional changes and maintaining positional accuracy.
Data Source
AI summary
An optical element device includes an opto-electric hybrid board sequentially including an optical waveguide having a mirror, and an electric circuit board having a terminal in a thickness direction, and an optical element optically connected to the mirror and electrically connected to the terminal. The opto-electric hybrid board includes a mounting region including the mirror and the terminal when projected in the thickness direction and mounted with the optical element. Furthermore, the opto-electric hybrid board includes an alignment mark for aligning the optical element with respect to the mirror. The alignment mark is made of a material for forming the optical waveguide, and disposed at both outer sides of the mounting region in a width direction.