Back-Illuminated Light Sensor Masking for Stray Light Shielding
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Solution Overview
Problem
Back-illuminated light detection devices face degradation in detection accuracy due to stray light incident from the side surface of the light receiving element, and existing light shielding underfills are insufficient in preventing this issue.
Innovation Solution
A light detection device configuration that includes a frame-shaped light shielding mask with a narrowing opening and a light shielding layer on its inner surface, where the underfill reaches the gap between the light receiving element and the light shielding layer, providing stable fixing strength and effective light shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a resin containing filler having light shielding property is used as underfill, then light shielding capability is improved, but detection accuracy is still degraded due to insufficient shielding across all wavelengths
Solution Approach 1:
The patent uses a resin containing filler particles with light shielding property to create an underfill material that provides comprehensive wavelength coverage. The composite structure combines the adhesive properties of resin with the optical shielding properties of filler particles, achieving both reliable bonding and effective light shielding across different wavelengths.
Solution Approach 2:
The patent modifies the optical parameters of the underfill by incorporating filler materials with specific light shielding characteristics. This changes the refractive index and light absorption properties of the underfill, enabling it to prevent stray light from reaching the light receiving element's side surface while maintaining its bonding function.
2Reliability
If underfill reaches side surface of light receiving element to ensure reliable bonding, then bonding reliability is improved, but detection accuracy is degraded due to stray light incident from side surface
Solution Approach 1:
The patent uses the underfill as a flexible bonding material that can adapt to the interface between the light receiving element and circuit element. The underfill forms a thin film layer that provides mechanical bonding while its light shielding properties prevent stray light from reaching the side surface of the light receiving element.
Solution Approach 2:
The underfill acts as an intermediary material between the light receiving element and the circuit element. It simultaneously provides bonding functionality and light shielding, mediating between the mechanical connection requirement and the optical isolation requirement.
3Object-affected harmful factors
If frame-shaped light shielding mask with narrowing opening is used, then light shielding effectiveness is improved, but manufacturing complexity increases
Solution Approach 1:
The light shielding mask is segmented into a frame-shaped structure with a narrowing opening, dividing the shielding function into different spatial zones. The frame portion provides structural support and peripheral shielding, while the narrowing opening provides focused shielding at the critical interface region.
Solution Approach 2:
The mask features an asymmetric narrowing opening that is wider at the first opening edge and narrower at the second opening edge. This asymmetric geometry is optimized to match the light propagation paths and provide enhanced shielding effectiveness where stray light is most problematic.
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
The configuration effectively prevents stray light from degrading detection accuracy, ensures stable fixing strength, and protects the light receiving element from external forces and moisture, while maintaining mechanical strength and uniformity among light receiving portions.
Implementation Method 1
the light shielding mask includes a frame having an opening in which the light receiving element is located and a light shielding layer formed on an inner surface of the opening
Implementation Method 2
a resin containing a filler having a light shielding property is used as an underfill
Implementation Method 3
an underfill disposed between the light receiving element and the circuit element
Data Source
AI summary
A light detection device includes: a back-illuminated light receiving element; a circuit element; a connection member; an underfill; and a light shielding mask. The light shielding mask includes a frame having an opening and a light shielding layer formed on an inner surface of the opening. A first opening edge on the side of the circuit element in the opening is located at the outside of an outer edge of the light receiving element. A second opening edge opposite to the circuit element in the opening is located at the inside of the outer edge of the light receiving element. The opening is narrowed from the first opening edge toward the second opening edge. A width of the frame increases from the first opening edge toward the second opening edge. The underfill reaches a gap between the light receiving element and the light shielding layer.