Optical Packaging Cap With Opaque Windows to Block Stray Light
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Solution Overview
Problem
Existing optical sensor systems face issues with mechanical stress and performance degradation due to the use of clear mold materials with high coefficients of thermal expansion and low glass transition temperatures, leading to potential device failure and light obstruction or scattering.
Innovation Solution
An optical system design featuring a cap with opaque and transparent regions on a transparent substrate, which encloses the optical emitter or detector devices without the need for clear mold materials, preventing stray light and allowing light to be emitted or received without obstruction, while providing mechanical protection and accommodating differences in thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clear mold material is used to encapsulate optical emitter and detector devices, then the devices are protected from the external environment, but high stress levels occur between the mold material and devices due to CTE mismatch and low Tg, leading to device failure
Solution Approach 1:
The patent removes the clear mold material encapsulation entirely, extracting the problematic component that caused stress. Instead of encapsulating the optical devices in mold material, the invention uses a different packaging approach with a cap and PCB structure that provides protection without the CTE mismatch and low Tg issues inherent in traditional mold materials.
Solution Approach 2:
The invention changes the material parameters by eliminating the clear mold material and replacing it with a cap structure and PCB assembly. This fundamental parameter change avoids the CTE mismatch and low glass transition temperature problems that caused high stress levels and device failure in the prior art.
2Reliability
If clear mold material is used to encapsulate optical devices, then devices are protected from environment, but the material absorbs moisture easily and creates artifacts such as voids and bubbles, negatively affecting optical transmission and device performance
Solution Approach 1:
The patent extracts and removes the clear mold material that caused moisture absorption and artifact formation. By eliminating this material entirely and using a cap-PCB packaging structure instead, the invention prevents the harmful effects of moisture uptake and void/bubble formation that degraded optical transmission quality.
Solution Approach 2:
The invention uses a composite packaging structure consisting of a cap and PCB assembly rather than a single mold material. This composite approach provides environmental protection while avoiding the moisture absorption and artifact issues inherent in clear epoxy mold materials.
3Reliability
If opaque cap is used to prevent stray light and reduce cross-talk, then cross-talk is reduced, but the cap structure adds complexity to the manufacturing process
Solution Approach 1:
The patent merges the cap structure with the PCB assembly, integrating the stray light prevention function into the existing packaging structure. By combining these elements, the invention reduces cross-talk without significantly increasing manufacturing complexity, as the cap and PCB work together as an integrated unit rather than separate 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 design enhances the reliability and performance of optical systems by reducing mechanical stress and light interference, preventing device failure, and maintaining light transmission quality.
Implementation Method 1
the one or more opaque regions of the cap are configured to prevent light emitted from the optical emitter device from travelling out of the chamber in one or more undesirable directions
Implementation Method 2
the one or more transparent regions of the cap are configured to allow light emitted from the optical emitter device to travel out of the chamber in one or more desirable directions
Implementation Method 3
the cap and the circuit board together define a chamber therebetween, the chamber enclosing the optical emitter device
Data Source
AI summary
An optical system includes a circuit board, an optical emitter device mounted on the circuit board, and a cap mounted on the circuit board. The cap and the circuit board together define a chamber therebetween, the chamber enclosing the optical emitter device. The cap includes one or more opaque regions and one or more transparent regions, wherein the one or more opaque regions of the cap are configured to prevent light emitted from the optical emitter device from travelling out of the chamber in one or more undesirable directions, wherein the one or more transparent regions of the cap are configured to allow light emitted from the optical emitter device to travel out of the chamber in one or more desirable directions. The cap is formed by rendering one or more selected regions of a transparent substrate to be opaque, or by forming one or more opaque features on a transparent substrate, so that the one or more opaque regions of the cap include the one or more opaque regions of the substrate or the one or more opaque features formed on the substrate, and so that the one or more transparent regions of the cap include one or more transparent regions of the substrate. The optical system may include one or more optical emitter devices and/or one or more optical detector devices.