Image Sensor Package Layout for Low-Light Noise Reduction
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Solution Overview
Problem
Image sensor packages suffer from light-sensing noise issues such as ghost images and flare due to the matrix arrangement of filter units and high reflectivity of the adhesive layer, which degrade image quality.
Innovation Solution
Incorporating a black matrix among the filter units of the color filter and a black adhesive layer that covers the non-sensitive area, which absorbs incident light and prevents reflection, thereby reducing light-sensing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If filter units and photosensitive units are arranged in a matrix, then the image sensor can capture color information, but ghost images are formed due to light passing through adjacent filter units
Solution Approach 1:
The patent divides the color filter structure into separate filter units arranged in a matrix, with each filter unit corresponding to a specific photosensitive unit. This segmentation isolates the optical path for each color channel, preventing light from one filter unit from reaching adjacent photosensitive units and causing ghost images.
Solution Approach 2:
The patent introduces a black matrix as an intermediary structure between adjacent filter units. This black matrix absorbs stray light and prevents it from reaching photosensitive units, thereby eliminating the ghost image effect while maintaining the matrix arrangement for color sensing.
2Strength
If a transparent adhesive layer with high reflectivity is used to mount the glass cover, then the glass cover can be securely attached, but the adhesive layer causes flare due to diffusive reflection of incident light
Solution Approach 1:
The patent changes the color/reflectivity property of the adhesive layer from transparent (high reflectivity) to black (high absorption). This color change transforms the adhesive layer from a reflective surface that causes flare into an absorptive surface that eliminates the harmful diffusive reflection while maintaining bonding functionality.
3Difficulty of detecting and measuring
If the adhesive layer is made transparent for visibility, then the mounting structure can be inspected, but light-sensing noise increases due to high reflectivity
Solution Approach 1:
The patent changes the adhesive layer from transparent to black, transforming it from a reflective surface that generates light-sensing noise into an absorptive surface that eliminates noise. The black color provides high light absorption while the adhesive layer maintains its bonding function.
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 black matrix and black adhesive layer significantly reduce ghost images and flare, enhancing image quality by minimizing light-sensing noise.
Implementation Method 1
the black matrix formed among the filter units... the incident light passing through one of the filter units and traveling to one of the photosensitive units adjacent to the filter unit is absorbed by the black matrix
Implementation Method 2
the incident light passing through the glass cover and emitting to the non-sensitive area is directly absorbed by the black adhesive layer
Data Source
AI summary
An image sensor package with low light-sensing noise has a chip body having a photosensitive area and non-sensitive area. The photosensitive area includes a photosensitive layer having a plurality of photosensitive units. A color filter is disposed on the photosensitive layer and has a plurality of filter units corresponding to the photosensitive units and a black matrix. A black adhesive layer is disposed on the non-sensitive area for mounting a glass cover. A gap is kept between the glass cover and the first surface of the chip body. When an incident light passes through the glass cover and emits to the photosensitive area, the black matrix absorbs the light traveling through the filter unit toward the photosensitive units adjacent to the filter unit. Furthermore, a light emitting to the non-sensitive area can be absorbed by the black adhesive layer. Thus, a light-sensing noise of the chip can be effectively decreased.