Image Sensor Package Lid Structure for Bond Pad Flare Reduction
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Solution Overview
Problem
Semiconductor device packages, particularly image sensor packages, face issues with light reflection and scattering from metal bond pads and bonding glue, leading to flare in images collected by the sensor, and obstructed visual inspection paths for packaging defects.
Innovation Solution
Incorporating an optically opaque layer directly coupled over the bond pads within an adhesive dam, which completely covers the bond pads, to prevent electromagnetic radiation from reaching them, thereby reducing reflection and scattering, and using an optically transmissive lid coupled with an adhesive dam to support the image sensor die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an optically opaque layer is added to cover bond pads, then light reflection and scattering is reduced, but device complexity increases
Solution Approach 1:
The optically opaque layer is nested within the adhesive dam structure, which itself is integrated into the packaging assembly. The adhesive dam contains both the optically opaque layer covering bond pads and the optically transmissive lid, creating a nested configuration where multiple functional layers are contained within each other without requiring separate external components.
Solution Approach 2:
The adhesive dam serves multiple functions: it provides structural support for the optically transmissive lid, contains the optically opaque layer to prevent light reflection from bond pads, and seals the packaging. This multi-functional design eliminates the need for separate components dedicated solely to light blocking, thereby reducing overall device complexity while still achieving the desired optical performance.
2Difficulty of detecting and measuring
If an optically opaque layer is added to cover bond pads, then visual inspection of packaging defects is improved, but manufacturing complexity increases
Solution Approach 1:
The optically opaque layer is merged with the adhesive dam structure, combining the light-blocking function with the existing sealing and support functions. This integration means that a single manufacturing process can deposit or apply the optically opaque material as part of the adhesive dam formation, rather than requiring a separate subsequent step to add a distinct light-blocking component.
Solution Approach 2:
The optically opaque layer is applied and positioned during the initial packaging assembly process, before final inspection and testing. By incorporating the light-blocking function early in manufacturing, the structure is prepared in advance for optimal visual inspection, eliminating the need for additional post-assembly modifications or separate inspection preparation steps.
3Illumination intensity
If an optically transmissive lid is used to support the image sensor die, then optical performance is maintained, but protection against moisture and contaminants is reduced
Solution Approach 1:
The packaging employs composite material strategies where the optically transmissive lid works in conjunction with the adhesive dam containing optically opaque layers. The adhesive dam material is selected to provide both mechanical sealing properties for moisture and contaminant protection and optical properties that allow it to contain the opaque layers effectively. This composite approach maintains optical transmission while enhancing protective functionality.
Solution Approach 2:
The packaging structure is segmented into distinct functional zones: the optically transmissive lid provides optical access and structural support, while the adhesive dam creates a separate sealed compartment that contains the bond pads and provides environmental protection. This segmentation allows each component to optimize its primary function without compromising the other, maintaining both optical performance and protective capabilities.
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
Significantly reduces observed flare by eliminating reflection from bond pads and improves reliability by allowing for better visual inspection of packaging defects, enhancing the long-term performance of image sensor packages.
Implementation Method 1
Incorporating an optically opaque layer directly coupled over the bond pads within an adhesive dam, which completely covers the bond pads, to prevent electromagnetic radiation from reaching them, thereby reducing reflection and scattering
Implementation Method 2
an adhesive dam including a first layer directly coupled to a largest planar surface of the optically transmissive lid and a second optically opaque layer coupled over the bond pad
Data Source
AI summary
An image sensor package may include an image sensor die including a bond pad and an optically transmissive lid coupled over the bond pad at an adhesive dam, the adhesive dam including a first layer directly coupled to a largest planar surface of the optically transmissive lid and a second optically opaque layer coupled over the bond pad.