Embedded Image Sensor Package Hermetic Sealing
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Solution Overview
Problem
Conventional image sensor packages face challenges with moisture ingress, thermal dissipation, and reliability due to the use of liquid encapsulants, polymer dams, and wirebonds, which can lead to delamination, crack growth, and reduced longevity.
Innovation Solution
The development of embedded image sensor packages that utilize a transparent cover, an electrically conductive layer, and an image sensor chip with a hermetically sealed cavity formed using underfill material, eliminating the need for liquid encapsulants and polymer dams, and incorporating thermal dissipation metals and embedded devices like processors within the package structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid encapsulants and polymer dams are used to seal the package, then moisture protection is achieved, but delamination and crack growth occur reducing reliability
Solution Approach 1:
The patent removes liquid encapsulants and polymer dams from the package structure, replacing them with a hermetically sealed cavity formed by the transparent cover and underfill material. This extraction eliminates the sources of delamination and crack growth while maintaining moisture protection through the alternative sealing approach using the underfill material and cover configuration.
Solution Approach 2:
The patent employs a composite sealing structure combining the transparent cover, underfill material, and hermetically sealed cavity to achieve moisture protection without the harmful effects of traditional liquid encapsulants. The underfill material serves dual functions as both adhesive and hermetic sealant, creating a composite solution that improves reliability while preventing moisture ingress.
2Reliability
If conventional packaging structures with multiple layers and components are used, then protection is achieved, but package size increases and processing complexity increases
Solution Approach 1:
The patent merges multiple functions into the underfill material and hermetically sealed cavity structure. The underfill material simultaneously provides adhesive bonding, hermetic sealing, and mechanical support, eliminating the need for separate liquid encapsulant and polymer dam components. This consolidation reduces processing steps while maintaining or improving package reliability.
Solution Approach 2:
The hermetically sealed cavity structure serves multiple functions: it provides mechanical support for the image sensor chip, creates a protected environment against moisture and contaminants, and eliminates the need for wirebonds through direct electrical coupling. This multi-functional design reduces overall package complexity and processing requirements.
3Reliability
If wirebonds are used for electrical coupling, then electrical connection is achieved, but package reliability decreases due to crack growth
Solution Approach 1:
The patent extracts wirebonds from the package structure and replaces them with direct electrical coupling between the image sensor chip and the electrically conductive layer. This elimination of wirebonds removes the source of crack growth and reliability issues while simplifying the manufacturing process through direct bonding methods.
Solution Approach 2:
The patent replaces the mechanical wirebonding system with a direct electrical coupling system using bumps or conductive structures. This substitution eliminates the mechanical stress and potential for crack growth associated with wirebonds while achieving reliable electrical connection through more robust direct bonding methods.
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 solution enhances package reliability by preventing moisture ingress, improving thermal management, and reducing the risk of delamination, while allowing for a smaller package size and fewer processing steps, thus increasing the longevity and efficiency of the image sensor.
Implementation Method 1
the image sensor chip and the transparent cover at least partially define a cavity that is hermetically sealed using an underfill material
Implementation Method 2
the image sensor chip electrically coupled with the electrically conductive layer at the first side of the image sensor chip, the image sensor chip coupled over the first layer
Implementation Method 3
an electrically conductive layer coupled in or over the first layer and electrically coupled with one or more electrical contacts exposed on an outer surface of the package
Implementation Method 4
a transparent cover having a first side and a second side opposite the first side; the first side of the image sensor chip including an image sensor, the image sensor chip coupled over the first layer so that the first side of the image sensor chip faces the second side of the transparent cover through the opening
Data Source
AI summary
An embedded image sensor package including a transparent cover having a first side and an opposing second side. A first layer couples over the second side of the transparent cover and has an opening. An electrically conductive layer couples in or over the first layer and electrically couples with one or more electrical contacts exposed on an outer surface of the package. An image sensor chip having a first side with an image sensor and an opposing second side electrically couples with the electrically conductive layer at the first side of the image sensor chip. The image sensor chip couples over the first layer so the first side of the image sensor chip faces the second side of the transparent cover through the opening. The image sensor chip, first layer, and transparent cover at least partially define a cavity hermetically sealed using an underfill material. The package includes no wirebonds.