Optical Sensor Package Adhesive Layout for Low Stray Light
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Solution Overview
Problem
Conventional optical semiconductor devices face challenges in achieving high reliability in thermal shock tests while minimizing optical noise, particularly due to issues with bonding reliability between the rib member and semiconductor substrate, and the generation of optical noise such as flares and ghosts when exposed to intense light.
Innovation Solution
An optical semiconductor device design featuring a semiconductor substrate with a light-receiving element, a frame-shaped rib member, and a transparent substrate, where the adhesive layer surrounds the light-receiving element, protrudes outward from the rib member, and has a coverage ratio of 30% or less on the inner peripheral surface of the rib member, effectively reducing optical noise by minimizing stray light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesive layer coverage on the inner peripheral surface of the rib member is increased to improve bonding reliability, then bonding reliability is improved, but optical noise generation is increased
Solution Approach 1:
The adhesive layer is applied selectively to specific regions of the rib member's outer peripheral surface while deliberately excluding the inner peripheral surface. This local differentiation ensures bonding reliability at the bonding interface (outer surface) while preventing optical noise by avoiding adhesive presence on the light-exposed inner surface where it would cause stray light reflection.
2Strength
If the adhesive layer is applied extensively on the rib member to ensure bonding strength, then bonding strength is improved, but stray light reflection is increased
Solution Approach 1:
The rib member surface is segmented into two functional zones: the outer peripheral surface that requires adhesive coverage for bonding strength, and the inner peripheral surface that must remain free of adhesive to prevent stray light reflection. This segmentation allows each surface to fulfill its specific function without compromising the other.
3Reliability
If the adhesive layer protrudes outward from the rib member to enhance bonding, then bonding reliability is improved, but device complexity is increased
Solution Approach 1:
The adhesive layer is applied in excess relative to the minimum bonding requirement, deliberately protruding outward from the rib member's outer peripheral surface. This excessive application ensures sufficient bonding reliability and creates a visible bonding interface, while the excess adhesive is strategically positioned away from the inner peripheral surface to avoid optical noise.
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 design enhances the reliability of the optical semiconductor device in thermal shock tests and suppresses the generation of optical noise, ensuring improved imaging characteristics by stabilizing the bond between the rib member and semiconductor substrate and reducing stray light reflection.
Implementation Method 1
an adhesive layer bonding the rib member and the semiconductor substrate to each other
Implementation Method 2
the rib member includes a cured product of a photosensitive composition, the photosensitive composition containing a curable compound having a polymerizable group, and a photopolymerization initiator
Data Source
AI summary
An optical semiconductor device includes a semiconductor substrate provided with a light-receiving element, a frame-shaped rib member, and a transparent substrate in this order, and an adhesive layer bonding the rib member and the semiconductor substrate to each other. The rib member and the adhesive layer are provided so as to surround the light-receiving element. In the optical semiconductor device, the adhesive layer protrudes outward from an outer peripheral surface of the rib member when the rib member and the adhesive layer are viewed from a transparent substrate side. A coverage ratio of the adhesive layer on an inner peripheral surface of the rib member is 30% or less.