Image Sensor Package Dam Structure Against Adhesive Penetration
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Solution Overview
Problem
Existing image sensor packages face issues with adhesive layers penetrating into the sensor unit, leading to reduced stability and reliability, particularly in structures like chip on board (COB), chip on flexible PCB (COF), chip on glass (COG), wafer level chip scale package (WLCSP), and image sensor ball grid array (IBGA).
Innovation Solution
The image sensor package incorporates a dam structure with multiple dams on the substrate, a glass plate on the dam structure, and an adhesive layer surrounding it, ensuring the adhesive does not penetrate into the sensor unit, and includes a redistribution layer with external connection terminals and a through electrode for improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional adhesive layer structure is used in image sensor packages, then the package can be assembled, but the adhesive layer penetrates into the sensor unit causing reduced stability and reliability
Solution Approach 1:
The adhesive layer is segmented into multiple discrete adhesive regions positioned at specific locations around the sensor unit rather than forming a continuous layer. This segmentation prevents the adhesive from penetrating into the sensor unit while still providing adequate bonding and structural support at critical points.
Solution Approach 2:
A reflective layer is introduced as an intermediary between the adhesive layer and the sensor unit. This reflective layer acts as a barrier that prevents adhesive penetration into the sensor unit while maintaining the structural integrity and bonding function of the adhesive layer.
2Reliability
If the sensor unit is made more stable by preventing adhesive penetration, then reliability improves, but the package structure becomes more complex
Solution Approach 1:
The reflective layer serves multiple functions simultaneously: it prevents adhesive penetration into the sensor unit, provides optical reflection functionality, and maintains structural support. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall package complexity.
3Volume of moving object
If the package size is reduced, then form factor improves, but the stability and reliability of the sensor unit may be compromised
Solution Approach 1:
The segmented adhesive layer configuration allows for reduced package size by eliminating the need for a continuous adhesive layer extending far from the sensor unit. Adhesive is placed only where structurally necessary, reducing overall material usage and package volume while maintaining stability.
Solution Approach 2:
The use of thin film structures and compact layer arrangements enables size reduction of the package while maintaining the functional integrity and stability of the sensor unit through the reflective layer barrier and optimized adhesive placement.
Data Source
AI summary
An image sensor package includes an image semiconductor chip, and an image sensor in the image semiconductor chip. The package includes a dam structure on a substrate of the image semiconductor chip, and the dam structure includes a plurality of dams. The package includes a glass plate on the dam structure. A top surface of the dam structure and a bottom surface of the glass plate are on a substantially same plane, and the plurality of dams are apart from one another by one or more air gaps.