Two-Stage Image Sensor Packaging Reduces Encapsulant Pressure
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Solution Overview
Problem
Conventional image sensor packaging methods face issues with excessive pressure from encapsulant formation, leading to position shifts and breakage of bonding wires, and contamination of the sensing area, which reduces yield and affects sensor functionality.
Innovation Solution
A two-stage packaging method where a first encapsulant layer is formed around the bonding wires and the image sensor chip, followed by a second encapsulant layer covering the outer portions, both with controlled pressure to minimize impact on the chip and wires, using a substrate and transparent board with an intermediate to enclose the sensing area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-stage encapsulant formation process is used, then the packaging process is simple and fast, but excessive pressure is generated causing position shift of the image sensor chip and breakage of bonding wires
Solution Approach 1:
The encapsulant formation process is divided into two stages: first forming a support structure (such as a mold or temporary support layer) to provide mechanical support, then forming the encapsulant layer in a controlled manner. This segmentation reduces the pressure exerted on the image sensor chip and bonding wires during encapsulant formation, preventing position shift and breakage while maintaining packaging efficiency
2Device complexity
If a single-stage encapsulant formation process is used, then the packaging process is simple, but the bonding wires are likely to break due to excessive pressure
Solution Approach 1:
A support structure or temporary support layer is formed beforehand before applying the encapsulant material. This cushioning structure distributes and reduces the pressure during encapsulant formation, protecting the bonding wires from breakage. The support structure is subsequently removed or integrated into the final package, maintaining bonding wire integrity throughout the process
3Strength
If the encapsulant is formed under high pressure, then the encapsulant layer is densely formed, but the image sensor chip may be contaminated through gaps between the chip and transparent board
Solution Approach 1:
A seal structure or barrier layer is formed preliminarily around the image sensor chip before applying the encapsulant material. This preliminary seal prevents encapsulant material from leaking into gaps between the chip and transparent board during the encapsulation process, avoiding contamination of the sensing area while still allowing dense encapsulant formation for protection
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 method reduces pressure on the image sensor chip and bonding wires, increasing packaging yield, quality, and reducing manufacturing costs while maintaining sensor sensitivity.
Implementation Method 1
the first encapsulant is subsequently cured to form the first encapsulant layer... and a second encapsulant covers an outer portion of the first encapsulant layer and is subsequently cured to form the second encapsulant layer
Data Source
AI summary
A two-stage packaging method of image sensors is disclosed. The packaging method includes the following steps: providing a substrate, fixing an image sensor chip on the substrate, fixing a transparent board on the image sensor chip, electrically connecting the image sensor chip and the substrate, forming a first encapsulant lay, and forming a second encapsulant layer. The two-stage packaging method prevents excessive pressure from being generated by formation of the encapsulant layers during the image sensor packaging process. Such excessive pressure, if generated, may result in position shift of the image sensor chip or damage of the bonding wires. The two-stage packaging method can increase the yield of the image sensor packaging process as well as the sensitivity of image sensors, thereby improving the quality and production of image sensor packaging while lowering the manufacturing costs.