Wafer Scale Image Sensor Package Light Blocking Layer
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Solution Overview
Problem
Wafer scale packaging of image sensor chips using transparent materials like glass or epoxy allows ambient light to interfere with the operation of the image sensor, degrading its performance, as there is no black cavity to block external light.
Innovation Solution
A wafer scale image sensor package is designed with a die, an intermediate layer, and a transparent layer, incorporating a filter layer and a light blocking layer to secure the chip to a substrate, ensuring that only specific wavelengths of light are allowed to pass through while blocking unnecessary light, using a securing member with transparent areas acting as lens structures to guide light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transparent materials (glass or epoxy) are used to enclose the die in wafer scale packaging, then the manufacturing process is simplified and chip scale packaging is achieved, but ambient light can pass through to interfere with the image sensor chip operation
Solution Approach 1:
The transparent encapsulation layer is segmented into multiple functional layers: a first transparent layer for light transmission and a second transparent layer with light-blocking patterns. This segmentation allows the packaging to simultaneously achieve transparency for simplified manufacturing and light blocking for sensor protection.
Solution Approach 2:
The packaging structure transitions from uniform transparency to localized optical properties. The second transparent layer contains light-blocking regions at specific positions (such as around the active area) while maintaining transparency in other areas, providing local light blocking where needed without compromising overall light transmission functionality.
2Object-affected harmful factors
If a black cavity is used to block ambient light in traditional chip packaging, then light interference is prevented, but the packaging complexity increases and wafer scale packaging advantages are lost
Solution Approach 1:
The light-blocking function is merged into the transparent encapsulation layer itself through the second transparent layer with light-blocking patterns, rather than being a separate black cavity structure. This integration maintains the simplicity of wafer scale packaging while achieving light blocking functionality.
Solution Approach 2:
The packaging uses composite transparent materials with different optical properties - the first transparent layer provides general light transmission while the second transparent layer provides selective light blocking. This composite approach achieves both transparency and light blocking without requiring opaque materials or complex cavity structures.
3Adaptability or versatility
If the image sensor chip is exposed to ambient light through transparent packaging, then the sensor can detect reflected light for applications like optical mice, but unnecessary ambient light degrades sensor performance
Solution Approach 1:
The second transparent layer is configured with light-blocking patterns at specific locations (such as around the active area boundaries) while leaving other areas transparent. This local differentiation allows the sensor to receive useful reflected light from the target surface while blocking stray ambient light from directions that would cause interference.
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 configuration effectively prevents ambient light from interfering with the image sensor's operation, maintaining performance by securely mounting the image sensor chip and light source on a substrate while allowing desired wavelengths to pass through, thus enhancing the image sensor's functionality.
Implementation Method 1
a filter layer and a light blocking layer are formed on at least a partial surface of the transparent layer
Implementation Method 2
block or absorb unnecessary light
Implementation Method 3
transparent materials, e.g. glass or epoxy, to enclose the die to form a package structure
Implementation Method 4
a securing member with transparent areas acting as lens structures to guide light effectively
Data Source
AI summary
There is provided an optical mechanism including a substrate, an image chip, a light source and a securing member. The image chip and the light source are attached to the substrate. The securing member is secured to the substrate and includes a first containing space for accommodating the light source, a second containing space for accommodating the image chip and a blocking region between the first containing space and the second containing space.