Optoelectronic Module Wall Structure for Optical Isolation
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Solution Overview
Problem
Optoelectronic modules with multiple radiation-sensitive regions face challenges in preventing optical cross-talk due to the need for a light-tight divider that does not allow direct light transmission between sensitive areas, while also avoiding contamination of these regions by adhesives used in their fabrication.
Innovation Solution
The module employs a wall with a bridge region and adhesive-filled conduits that span across the image sensor, using a dual-cure adhesive to ensure the adhesive does not contaminate sensitive regions, and a spacer composed of the same material as the bridge, which is formed as a single contiguous unitary piece, to prevent light leakage and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wall is used to separate the image sensor into multiple optically isolated regions, then optical cross-talk between regions is prevented, but adhesive contamination of sensitive regions may occur during fabrication
Solution Approach 1:
The wall structure is segmented into a bridge portion and a distal portion, with the adhesive application area separated from the sensitive sensor regions. This segmentation allows adhesive to be confined to non-sensitive areas while maintaining optical isolation functionality.
Solution Approach 2:
The bridge portion acts as an intermediary structure that connects to the substrate while maintaining a controlled distance from the sensitive sensor regions. This intermediary structure enables adhesive application in the space between the bridge and sensor without direct contact with sensitive areas.
2Reliability
If a divider is used to separate sensor regions, then optical cross-talk is prevented, but the divider must be substantially light-tight which complicates the structure
Solution Approach 1:
The wall structure is merged with the bridge portion and spacer components to form an integrated assembly. The bridge portion and distal portion work together as a unified light-tight barrier, eliminating the need for separate divider components and reducing overall structural complexity.
Solution Approach 2:
The wall structure serves multiple functions: it provides optical isolation between regions, acts as a light-tight barrier, and integrates with the bridge and spacer to provide structural support. This multi-functionality reduces the need for additional components.
3Strength
If adhesive is used to secure the bridge portion to the substrate, then structural stability is achieved, but adhesive may contaminate optically sensitive regions
Solution Approach 1:
The adhesive is applied with specific local quality control, ensuring it fills only the space between the bridge portion and substrate in non-sensitive areas. The adhesive application is localized to specific regions that do not compromise optical sensitivity, achieving both structural stability and contamination control.
4Reliability
If the wall extends across the image sensor to prevent light leakage, then optical isolation is improved, but the risk of adhesive contamination to sensitive regions increases
Solution Approach 1:
The wall structure utilizes vertical dimensionality by extending from the substrate upward to meet the bridge portion, creating a three-dimensional light-tight barrier. This vertical extension achieves optical isolation without requiring horizontal expansion into sensitive sensor regions, thereby preventing adhesive contamination.
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 effectively prevents optical cross-talk between the regions and minimizes adhesive contamination, ensuring the module's sensitivity and accuracy in applications like proximity sensing and camera imaging.
Implementation Method 1
The wall further includes adhesive that fills an area between the bridge region and an upper surface of the image sensor
Implementation Method 2
The wall attenuates light at one or more wavelengths detectable by the image sensor
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
This disclosure describes optoelectronic modules that include an image sensor having at least two regions separated optically from one another by a wall. The wall can include a bridge portion that extends over the image sensor and further can include a cured adhesive portion, part of which is disposed between a lower surface of the bridge portion and an upper surface of the image sensor. Various techniques are described for fabricating the modules so as to help prevent the adhesive from contaminating sensitive regions of the image sensor. The wall can be substantially light-tight so as to prevent undesired optical cross-talk, for example, between a light emitter located to one side of the wall and a light sensitive region of the image sensor located to the other side of the wall.