Sealing Ring Blowout Prevention in Electronic Device Packages
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Solution Overview
Problem
Existing electronic device packages, particularly those using chip scale packages for photosensors, face challenges in preventing moisture and particle ingress due to inadequate sealing, leading to defects such as sealing ring blowout during solder reflow processes, as conventional sealing rings with air vents or resin seals fail to maintain pressure equality and allow moisture penetration.
Innovation Solution
A sealed electronic device package is created using a stacked layer of a sealing layer and a low-melting-point material layer, forming a bonding layer through reaction between the low-melting-point material and the sealing layer and sealing ring pad, which prevents foreign substance ingress and sealing ring blowout by maintaining a solid state during high-temperature processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin sealing ring is used to seal the pixel region, then the pixel region is surrounded and protected, but moisture diffuses through the resin into the pixel region causing degradation
Solution Approach 1:
The patent changes the material parameter of the sealing ring from resin to solder material (SnAg), which has different moisture barrier properties. The solder material prevents moisture diffusion while maintaining sealing functionality, resolving the contradiction between sealing effectiveness and moisture resistance.
Solution Approach 2:
The patent uses a composite sealing ring structure combining solder material (SnAg) with specific structural features. This composite approach achieves both effective sealing and moisture blocking, overcoming the limitations of pure resin materials.
2Object-affected harmful factors
If a solder material sealing ring is used to prevent moisture ingress, then moisture blocking is improved, but high pressure during solder reflow causes the sealing ring to blow out
Solution Approach 1:
The patent segments the sealing ring into multiple parts: a closed loop shape with multiple air vents. This segmentation allows pressure equalization during reflow while maintaining the moisture-blocking sealed structure, resolving the contradiction between moisture blocking and pressure resistance.
Solution Approach 2:
The air vents create pressure equilibrium between the inside and outside of the sealing ring during solder reflow. By equalizing pressure (making both sides equipotential), the sealing ring avoids blowout while maintaining its moisture-blocking integrity.
3Stress or pressure
If air vents are added to the sealing ring to release pressure, then pressure equalization is achieved, but moisture can flow into the pixel region through the air vents
Solution Approach 1:
The patent applies local quality by making different parts of the sealing ring serve different functions: the closed loop portions provide moisture blocking, while the air vent portions provide pressure equalization. This local differentiation resolves the contradiction between pressure equalization and moisture ingress prevention.
4Reliability
If a closed loop sealing ring is formed on top of a polymer layer, then sealing is achieved, but moisture penetrates under the sealing ring during subsequent processing causing blowout
Solution Approach 1:
The patent changes the material parameter from polymer-based resin to solder material (SnAg), which has superior moisture barrier properties. This material parameter change prevents moisture penetration under the sealing ring during high-temperature processing, eliminating the blowout issue while maintaining sealing 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
The solution effectively prevents moisture and particle ingress, ensuring the integrity of the pixel region and preventing sealing ring blowout, thereby enhancing the reliability and longevity of the electronic device package by forming a strong, pressure-resistant bond between the device and substrate.
Implementation Method 1
a bonding layer is formed by the reaction between the low-melting-point material layer, and a sealing ring pad and the sealing layer when the low-melting-point material layer melts
Implementation Method 2
a bonding layer is formed by the reaction between the low-melting-point material layer, and a sealing ring pad and the sealing layer
Data Source
AI summary
An electronic device package includes a substrate assembly, an electronic device disposed to face the substrate assembly, and a sealing ring or rings including a sealing layer and a bonding layer that is disposed between the substrate assembly and the electronic device, wherein the sealing ring(s) has a closed loop shape surrounding a sealing region of the electronic device, and the bonding layer is formed through a reaction of the sealing layer and sealing layer pad with a low-melting-point material layer whose melting point is lower than that of the sealing layer and sealing ring pad. The bonding layer is formed of an intermetallic compound of the sealing layer, sealing ring pad and low-melting-point material that melts at a temperature greater than the melting temperature of the low-melting-point material. The device package also includes electrical connections in the form of joints between the substrate assembly and electronic device.