Image Sensor Package Cavities for Pollution Protection
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Solution Overview
Problem
During the packaging process of image sensors, the image sensing areas are prone to pollution or damage due to exposure, which affects the reliability and stability of the resulting package structure.
Innovation Solution
A method and structure where a second substrate with through holes and a tape film is used to create cavities around the image sensing areas, protecting them from damage, and the pads are exposed through cutting and dry plasma or laser stripping processes, eliminating the need for mask layers and reducing pollution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If COB packaging technology is used to attach image sensor chip directly onto circuit board, then integration level and manufacturing simplicity are improved, but image sensing areas are exposed and prone to pollution or damage
Solution Approach 1:
The patent applies preliminary action by pre-forming cavities in the substrate before mounting the image sensor chip. These cavities are prepared in advance to accommodate and protect the image sensing areas, eliminating the need for post-mounting protection steps while maintaining process simplicity.
Solution Approach 2:
The patent introduces cavities as an intermediary structure between the substrate and the image sensor chip. These cavities serve as protective chambers that house the image sensing areas, acting as a mediator that shields sensitive components from environmental pollution and mechanical damage while allowing electrical connections to be made.
2Ease of manufacture
If image sensor chip is mounted without protection device, then manufacturing process is simplified, but image sensing areas are prone to pollution or damage
Solution Approach 1:
The cavities are formed in the substrate before the image sensor chip is mounted, providing pre-established protection for the image sensing areas. This preliminary structuring eliminates the need for complex post-mounting protection devices while maintaining manufacturing simplicity.
Solution Approach 2:
The patent extracts the image sensing areas from direct exposure to the external environment by placing them inside cavities. This separation isolates the sensitive sensing regions from harmful external factors such as dust, moisture, and mechanical damage while keeping the pads accessible for electrical connections.
3Device complexity
If distances between adjacent pads are reduced to increase integration, then manufacturing precision requirements increase, but packaging difficulty increases
Solution Approach 1:
The patent segments the substrate into multiple cavities, each housing image sensing areas and their associated pads. This segmentation allows for modular processing where precision requirements are localized to individual cavity-pad assemblies rather than across the entire substrate, making it easier to maintain manufacturing precision as integration increases.
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 approach effectively protects the image sensing areas from pollution and damage, improves packaging efficiency, and enhances the mechanical stability of the package structure by forming cavities that isolate the sensing areas and expose the pads without causing additional harm.
Implementation Method 1
forming a tape film on an upper surface of the second substrate to seal one end of each of the plurality of through holes
Implementation Method 2
removing portions of the tape film and portions of the second substrate by cutting
Implementation Method 3
removing portions of the remained second substrate to expose the plurality of pads
Implementation Method 4
removing portions of the remained second substrate to expose the plurality of pads
Data Source
AI summary
Image sensor package structure and method are provided. The method includes: providing first substrate having upper surface on which image sensing areas and pads are formed; providing second substrate having through holes; forming tape film on upper surface of second substrate to seal each through hole; contacting lower surface of second substrate with upper surface of first substrate to make image sensing areas in through holes; removing portions of tape film and second substrate, wherein remained tape film and second substrate form cavities including sidewalls made of second substrate and caps sealing sidewalls and made of tape film, and remained second substrate also covers pads; removing portions of remained second substrate to expose pads; slicing first substrate to form single image sensor chips including image sensing areas and pads; and electrically connecting pads with circuits on third substrate through wires. Pollution or damage to image sensing areas may be avoided.