Image Sensor Package Dam Structure for Stress Crack Relief
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Solution Overview
Problem
Image sensor packages, particularly those with an IBGA structure used in vehicles, face reliability issues due to stress-related cracks and delamination phenomena during the curing process of the dam layer, which affects the package's integrity and performance.
Innovation Solution
Incorporating a stress relaxation layer (SRL) with lower viscosity than the body layer in the dam structure of the image sensor package, which relieves stress and prevents cracks and delamination, thereby enhancing the package's reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dam layer is formed during the curing process, then the package structure is established, but stress-related cracks and delamination occur reducing reliability
Solution Approach 1:
The dam layer is segmented into multiple layers with different viscosities. The lower layer has higher viscosity to provide structural support, while the upper layer has lower viscosity to allow stress relaxation. This segmentation prevents stress-related cracks and delamination while maintaining package reliability.
Solution Approach 2:
The viscosity parameter of the dam layer is changed by forming a multi-layer structure. The upper layer uses a material or formulation with lower viscosity compared to the lower layer, enabling stress relaxation during curing while the lower layer maintains structural integrity.
2Reliability
If a multi-layer dam structure with stress relaxation layer is used, then stress-related defects are reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The dam layer is divided into two distinct layers with different viscosity characteristics. This segmentation allows each layer to perform its specific function (structural support and stress relaxation) while maintaining overall simplicity in the manufacturing process through sequential application.
Solution Approach 2:
The dam structure uses a composite of two materials or formulations with different viscosity properties. The lower layer uses a higher viscosity material for structural stability, while the upper layer uses a lower viscosity material for stress relaxation, creating a composite structure that balances reliability and manufacturability.
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
The use of a stress relaxation layer with lower viscosity in the dam structure significantly improves the reliability of the image sensor package by reducing stress-related defects and ensuring the package's integrity and performance.
Implementation Method 1
The dam includes a stress relaxation layer (SRL) and a body layer on the SRL, and the SRL has a lower viscosity than a viscosity of the body layer
Data Source
AI summary
Provided are an image sensor package with improved reliability and a method of fabricating the same. The image sensor package includes: a package substrate; an image sensor chip provided on the package substrate, and including a pixel area and a peripheral area surrounding the pixel area; a dam in the peripheral area, the dam having a rectangular ring shape and surrounding the pixel area; a transparent cover provided on the dam and covering an upper portion of the image sensor chip; and a sealing material sealing the image sensor chip and covering side surfaces of the transparent cover. The dam includes a stress relaxation layer (SRL) and a body layer on the SRL, and the SRL has a lower viscosity than a viscosity of the body layer.