Optical Sensor Packaging with Light Barrier and Hollow Cavity
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Solution Overview
Problem
Current manufacturing methods for optical sensor arrangements, such as proximity and time-of-flight sensors, are complex and costly due to the need for precise optical isolation and sealing of components, particularly the light barrier between measurement and reference SPAD arrays, which is challenging to achieve over uneven surfaces.
Innovation Solution
A method involving the formation of a light barrier using an optically opaque material along the integrated circuit profile, followed by encapsulation with an optically transparent mold layer and a casing made from opaque material, which optically isolates the detector and emitter while allowing mechanical decoupling to reduce thermomechanical stress and crosstalk, using transfer molding techniques for cost efficiency and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light barrier is formed using traditional sealing methods over uneven surfaces, then optical isolation between measurement and reference SPAD arrays is achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent merges the light barrier formation with the mold layer encapsulation process. The mold layer serves dual functions: it encapsulates the SPAD arrays and simultaneously forms the light barrier structure. This integration eliminates the need for separate sealing components and processes, reducing manufacturing complexity while maintaining optical isolation reliability.
Solution Approach 2:
The mold layer is designed to perform multiple functions: mechanical encapsulation of the SPAD arrays, optical isolation between measurement and reference detectors, and structural support. By making the mold layer multi-functional, the patent reduces the total number of components needed, simplifying the device structure and manufacturing process.
2Reliability
If multiple individual components are used for light barrier and sealing structures, then optical isolation is achieved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple functions (encapsulation and light barrier formation) into a single mold layer structure, eliminating the need for separate sealing components. This reduction in component count directly lowers manufacturing costs while maintaining the required optical isolation between measurement and reference SPAD arrays.
Solution Approach 2:
The mold layer is designed as a multi-functional component that simultaneously provides mechanical protection, optical isolation, and structural support. This consolidation of functions into a single component reduces the bill of materials and assembly complexity, thereby reducing overall manufacturing cost.
3Stability of the object's composition
If the casing is rigidly connected to the mold layer, then structural stability is improved, but thermomechanical stress and crosstalk increase
Solution Approach 1:
The patent introduces a hollow space between the casing and the mold layer, effectively segmenting the structural connection. This gap acts as a mechanical decoupling element that allows the casing and mold layer to move independently in response to thermal expansion, reducing thermomechanical stress while maintaining structural stability through distributed support.
Solution Approach 2:
The hollow space serves as an intermediary element between the casing and mold layer. It provides mechanical decoupling that prevents direct transmission of thermomechanical stresses while still allowing the structure to maintain overall stability. The hollow space acts as a buffer zone that accommodates differential thermal expansion.
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 results in a cost-effective, reliable optical sensor arrangement with improved accuracy and reduced thermomechanical stress, enabling flexible adaptation for various applications by allowing precise control over light guidance and isolation, and enhancing detection accuracy in low light conditions.
Implementation Method 1
A light barrier is formed between the first optical detector and the light emitter. Forming the light barrier involves dispensing a first optically opaque material along the profile of the integrated circuit
Implementation Method 2
a mold layer is formed by encapsulating the substrate, the integrated circuit and the light emitter with an optically transparent material
Data Source
AI summary
A method of manufacturing an optical sensor arrangement including the steps of providing a substrate having a surface and providing an integrated circuit comprising an optical detector arranged for detecting light of a desired wavelength range. The integrated circuit and a light emitter are mounted onto the surface, wherein the light emitter is arranged for emitting light in the desired wavelength range. The integrated circuit and the light emitter are electrically connected to each other and to the substrate. A light barrier is formed between the optical detector and the light emitter by dispensing a first optically opaque material along a profile of the integrated circuit. A mold layer is formed by at least partly encapsulating the substrate, the integrated circuit and the light emitter with an optically transparent material. A casing, made from a second optically opaque material, is mounted on the light barrier and thereby encloses a hollow space between the casing and the mold layer.