Wafer-Level Package Seal Rings for Contamination Control
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Solution Overview
Problem
Conventional wafer-level packaging methods face challenges in achieving uniform gaps and airtight seals between substrates, leading to contamination of the active region and inefficient sealant usage, which affects the reliability and lifespan of electronic devices.
Innovation Solution
The package structure incorporates a first and second seal ring on the substrate, forming a channel for the sealant, with the second seal ring having a smaller height than the first, to control sealant distribution and prevent contamination, and optionally includes a third seal ring on the lower surface to further reduce sealant usage and enhance bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealant is applied to bond two substrates together in conventional wafer-level packaging, then the substrates are joined, but the sealant is flowable and cannot be precisely controlled, leading to excessive sealant usage and potential contamination of the active region
Solution Approach 1:
The patent divides the bonding interface into multiple discrete bonding points using protrusions on the first substrate that correspond to recesses on the second substrate. This segmentation replaces the continuous sealant application with localized bonding zones, preventing sealant flow while maintaining adhesion and airtightness.
Solution Approach 2:
The patent introduces protrusions and recesses as intermediary structures between the two substrates. These features act as mechanical interlocks that mediate the bonding process, eliminating the need for flowable sealant while ensuring reliable adhesion and airtight sealing.
2Length of stationary object
If spacer balls are used to maintain the gap between substrates, then the gap is formed, but the spacer balls may roll or slide if the applied force is not uniform, causing misalignment and non-uniform gaps
Solution Approach 1:
The patent replaces the single-gap structure with multiple localized bonding interfaces defined by protrusions and recesses. This segmentation provides multiple stable contact points that prevent substrate misalignment and ensure uniform gap distribution without relying on spacer balls.
Solution Approach 2:
Instead of using spacer balls to maintain the gap from the sides, the patent inverts the approach by using protrusions and recesses that define the gap structure directly at the bonding interface, providing inherent alignment and positional stability.
3Object-affected harmful factors
If a sealant is applied around the periphery of the active region to protect it, then the active region is isolated from contamination, but the sealant may flow onto the active region during bonding, causing contamination
Solution Approach 1:
The patent extracts the sealing function from the sealant material and transfers it to the mechanical interlock structure formed by protrusions and recesses. This eliminates the harmful flowable property of sealant while maintaining the protective sealing function around the active region.
Solution Approach 2:
The patent converts the potential harm of sealant flow into a benefit by replacing it with a structure that inherently prevents flow. The protrusions and recesses create a mechanical barrier that directs and contains any remaining sealant, turning the flowable property into a controlled sealing mechanism that protects rather than contaminates the active region.
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 configuration effectively reduces sealant usage, prevents active region contamination, and enhances adhesion and airtight performance, thereby extending the lifespan and reliability of electronic devices by ensuring uniform gaps and strong substrate bonding.
Implementation Method 1
A first seal ring of a first height is disposed on the upper surface of the first substrate and around the periphery of the predetermined area... A second seal ring having a second height smaller than the first height is disposed on the upper surface of the first substrate and around the first seal ring. The area enclosed between the first and second seal rings defines a channel. A sealant is disposed in the channel.
Implementation Method 2
The two substrates 102, 108 are bonded together via the sealant 112... enhances adhesion and airtight performance
Data Source
AI summary
A package structure is provided herein. The package structure includes a first substrate and a second substrate. A first seal ring having a first height is disposed around a predetermined area of the first substrate and between the first and second substrates. A second seal ring having a second height is disposed on the first substrate and around the first seal ring. A sealant is provided between the first and second seal rings to seal up the package structure.