Hermetic Image Sensor Package Structure for Moisture Ingress Control
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Solution Overview
Problem
As image sensor packages become smaller, the risk of die handling defects and moisture/contaminant ingress increases, compromising their performance.
Innovation Solution
The implementation of an image sensor package design featuring an optically transmissive cover, a first layer with openings, and an encapsulant that covers the sidewalls and interfaces, forming a cavity and providing a hermetic seal, along with a redistribution layer and electrical contacts, to prevent moisture and contaminants from entering the package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the image sensor package size is reduced, then the compactness and portability are improved, but the risk of die handling defects and moisture/contaminant ingress increases
Solution Approach 1:
The package structure is segmented into distinct functional layers: an optically transmissive cover forming a sealed cavity, an encapsulant coating the sidewalls and interfaces, and a substrate. This segmentation allows each layer to perform its specific function optimally while maintaining hermetic sealing in a compact form factor.
Solution Approach 2:
The encapsulant acts as an intermediary material that coats all sidewalls and interfaces between components. This intermediate layer provides hermetic sealing protection against moisture and contaminants, resolving the reliability issue that arises from miniaturization.
2Ease of manufacture
If conventional sealing methods using dry film or resin are used, then the manufacturing process is simple, but the hermetic sealing effectiveness is insufficient to prevent moisture and contaminant ingress
Solution Approach 1:
The encapsulant is applied as a thin film coating that conforms to all sidewalls and interfaces. This thin film approach provides superior hermetic sealing compared to conventional dry film or resin methods, while maintaining ease of manufacture through standard coating processes.
Solution Approach 2:
The sealing system uses composite construction with the encapsulant material providing hermetic properties, combined with the optically transmissive cover and substrate materials. This composite approach achieves both hermetic effectiveness and manufacturing simplicity.
3Reliability
If the encapsulant covers all interfaces and sidewalls, then the hermetic sealing and protection against contaminants are improved, but the manufacturing complexity increases
Solution Approach 1:
The encapsulant performs multiple functions simultaneously: it seals interfaces between components, coats sidewalls for environmental protection, and provides structural support. This multi-functionality reduces the need for separate sealing components, thereby simplifying the overall manufacturing process while maintaining comprehensive protection.
Data Source
AI summary
Implementations of image sensor packages may include an image sensor chip, a first layer including an opening therethrough coupled to a first side of the image sensor chip, and a optically transmissive cover coupled to the first layer. The optically transmissive cover, the first layer, and the image sensor chip may form a cavity within the image sensor. The image sensor package may also include at least one electrical contact coupled to a second side of the image sensor chip opposing the first side and an encapsulant coating an entirety of the sidewalls of the image sensor package.