Wafer-Level Packaging Cover Dike Structures for Image Sensor Separation
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Solution Overview
Problem
Conventional Wafer Level Packaging (WLP) technologies for image sensors face challenges in easily separating the packaging cover from the wafer without damaging the wafer, which affects the mechanical strength and cavity ratio, and can impact the performance of the image sensors.
Innovation Solution
A wafer level packaging structure that includes first dike structures covering the pads and scribe line regions on the wafer and second dike structures on the packaging cover, arranged corresponding to the scribe line regions, which are fixedly jointed via direct bonding or viscose, allowing the packaging cover to automatically separate during the cutting process without damaging the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a packaging cover is formed at photosensitive regions to protect them during packaging, then the photosensitive regions are protected from damage and contamination, but the light transmission is affected and the packaging cover must be separated from the wafer at the end of the packaging process
Solution Approach 1:
The packaging cover is segmented into multiple regions: a transparent region corresponding to the photosensitive region that allows light transmission, and an opaque region corresponding to the non-photosensitive region that blocks light. This segmentation resolves the contradiction by allowing light to pass through where needed while maintaining protection where not needed.
Solution Approach 2:
Different regions of the packaging cover have different optical properties - the region over the photosensitive area is made transparent to allow light transmission, while the region over non-photosensitive areas is made opaque to block light. This local differentiation resolves the contradiction between protection and light transmission.
2Object-generated harmful factors
If the packaging cover is separated from the wafer after packaging, then light transmission is restored, but it is difficult to separate without damaging the wafer
Solution Approach 1:
The bonding between the packaging cover and wafer is segmented to occur only at non-photosensitive regions through the opaque regions of the packaging cover. This allows the cover to be easily separated from the wafer at these bonding locations without requiring damage to the wafer, while maintaining protection over the photosensitive regions during packaging.
Solution Approach 2:
The packaging cover acts as an intermediary structure that provides protection during packaging but can be easily removed afterward. By designing the cover with transparent and opaque regions, it maintains protection where needed while allowing easy separation at non-photosensitive regions without damaging the wafer.
3Reliability
If conventional WLP technology is used with a packaging cover, then photosensitive regions are protected, but the mechanical strength and cavity ratio are affected
Solution Approach 1:
The packaging cover is segmented into transparent and opaque regions, with bonding occurring only at the opaque regions corresponding to non-photosensitive areas. This segmentation allows the cover to provide protection while maintaining the mechanical strength and cavity ratio of the wafer, as the bonding is localized to areas that do not interfere with the overall structural integrity.
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
Ensures the packaging cover separates from the wafer without damaging it, maintaining mechanical strength and cavity ratio, thus protecting the image sensors and facilitating efficient packaging.
Implementation Method 1
bottoms of the second dike structures and tops of the first dike structures adhered to each other through a direct bonding or by a viscose
Implementation Method 2
bottoms of the second dike structures and tops of the first dike structures adhered to each other through a direct bonding or by a viscose
Data Source
AI summary
A wafer level packaging structure for image sensors and a wafer level packaging method for image sensors are provided. The wafer level packaging structure includes: a wafer to be packaged including multiple chip regions and scribe line regions between the chip regions; pads and image sensing regions located on a first surface of the wafer and located in the chip regions; first dike structures covering surfaces of the pads and the scribe line regions; a packaging cover arranged facing the first surface of the wafer; and second dike structures located on a surface of the packaging cover. The second dike structures are arranged corresponding to the scribe line regions. The packaging cover and the wafer are jointed fixedly via the second dike structures and the first dike structures.