Wafer-Level Optical Sensor Packaging with Light Path Blocking
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Solution Overview
Problem
Existing optical sensor packaging technologies face challenges in achieving a small range of incident angles with a wide angular field of view, requiring complex and costly adjustments of interference filters and diffusers, making high-volume manufacturing inefficient.
Innovation Solution
A method of producing optical sensors at the wafer-level using multiple molding steps with optically transparent and opaque materials to create a light path blocking structure that reduces stray light, allowing for flexible and cost-effective packaging with integrated diffusers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If interference filters and diffusers are precisely adjusted to achieve a small range of incident angles with a wide angular field of view, then optical performance is improved, but device complexity and production cost increase
Solution Approach 1:
The packaging structure is divided into distinct functional components: a housing defining an aperture, a diffuser element positioned within the housing, and interference filters arranged in specific configurations. This segmentation allows each component to be optimized independently for its specific function while simplifying the overall manufacturing process through modular assembly
Solution Approach 2:
The housing structure serves multiple functions simultaneously: it defines the aperture for light entry, provides mechanical support for the diffuser and filters, and establishes the geometric relationships between components. This multi-functionality reduces the number of separate parts needed and simplifies production
2Manufacturing precision
If interference filters and diffusers are precisely adjusted to achieve a small range of incident angles with a wide angular field of view, then optical performance is improved, but production time and cost increase
Solution Approach 1:
The housing, diffuser, and filter assemblies are pre-configured with precise geometric relationships established during manufacturing. The diffuser is positioned at a predetermined distance from the aperture, and filters are arranged at specific angles and positions. These preliminary actions eliminate the need for complex post-assembly adjustments, thereby improving production efficiency
Solution Approach 2:
The design specifies particular geometric parameters (aperture size, diffuser distance, filter angles) that can be standardized for mass production. By fixing these parameters in the design phase, the manufacturing process becomes more efficient and less time-consuming while maintaining optimal optical performance
3Adaptability or versatility
If a diffuser is placed close to the aperture to increase the outside field of view, then field of view is improved, but stray light blocking becomes more difficult
Solution Approach 1:
The housing includes light-blocking features positioned at specific locations to address stray light problems locally. The blocking structure is configured to prevent stray light from entering through the aperture while allowing the diffuser to maintain its close positioning for wide field of view. This localized approach to light blocking preserves the benefits of the close diffuser placement
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 enables efficient and cost-effective packaging of optical sensors with improved light shielding and a wider field of view, reducing production costs and mechanical damage risks while maintaining optical performance.
Implementation Method 1
A light path blocking structure is arranged on the top surface and/or in the first mold structure to block light from entering via the at least one runner structure
Data Source
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Figure 3A~3C
AI summary
A method is proposed to produce an optical sensor at wafer-level, the methods comprises the following steps. A wafer (10) is provided and has a main top surface (11) and a main back surface (12). At or near the top surface (11) of the wafer at least one integrated circuit (20) is arranged having a light sensitive component (21). A first mold tool (1) is placed over the at least one integrated circuit such that at least one channel (37) remains between the first mold tool (1) and the top surface (11) to enter a first mold material. A first mold structure (30) is formed by wafer-level molding the first mold material via the at least one channel (37). The first mold material creates at least one runner structure (35). A second mold tool (2) is placed over the first mold structure (30) and a second mold structure (40) is formed by wafer-level molding a second mold material by means of the second mold tool (2). A light path blocking structure (50) is arranged on the top surface (11) to block light from entering via the at least one runner structure (35).