UV LED Package Oxygen Gas Sealing Carbide Deposition
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Solution Overview
Problem
Ultraviolet light-emitting LEDs experience reduced light output due to carbide deposition on their surfaces when sealed in packages, caused by flux residues from bonding materials, which are carbonized by the emitted light.
Innovation Solution
Incorporating an enclosed gas with an oxygen concentration of 5 vol. % or more within the package to prevent carbide deposition on the LED's surface, using a substrate with ceramic materials for heat dissipation and ultraviolet resistance, and employing a bonding material with grain boundaries and voids to manage flux residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ultraviolet light LED is sealed in a package with conventional bonding materials, then the LED can be hermetically mounted, but carbides are deposited on the LED surface causing light output reduction
Solution Approach 1:
The patent converts the harmful effect of flux residues by introducing oxygen into the sealed space. The oxygen causes the flux residues to oxidize and form a protective oxide layer instead of allowing them to carbonize and form harmful carbide deposits on the LED surface. This transforms a potentially harmful organic substance into a beneficial protective layer.
Solution Approach 2:
The patent changes the chemical composition parameter of the atmosphere inside the sealed space by introducing oxygen at a specific concentration (1-30 vol%). This parameter change prevents carbide formation by altering the chemical reaction pathway of the flux residues under ultraviolet irradiation.
2Object-generated harmful factors
If oxygen is introduced to prevent carbide deposition, then light output is maintained, but oxygen may react with hydrogen and form water causing short circuits
Solution Approach 1:
The patent precisely controls the oxygen concentration parameter within a specific range (1-30 vol%) to achieve sufficient oxidation of flux residues while minimizing water formation. Additionally, the moisture content is controlled to be 10 ppm or less, creating optimal conditions that prevent both carbide deposition and water condensation.
Solution Approach 2:
The patent creates a localized oxygen-rich environment specifically around the LED surface where flux residues are present, allowing oxidation to occur at the critical interface without requiring high oxygen concentrations throughout the entire sealed space, thus reducing water formation risk.
3Ease of manufacture
If bonding materials with flux are used to bond the LED, then hermetic mounting is achieved, but flux residues carbonize under ultraviolet light forming carbides
Solution Approach 1:
The patent accepts the presence of flux residues from conventional bonding materials but introduces oxygen to convert their degradation pathway from harmful carbide formation to beneficial oxide layer formation. This allows continued use of easy-to-manufacture bonding materials while eliminating their harmful effects.
Solution Approach 2:
The patent introduces oxygen as an intermediary substance that mediates between the flux residues and the ultraviolet light. Instead of allowing direct carbonization, the oxygen acts as a mediator that oxidizes the flux residues, preventing carbide formation while allowing the bonding material to remain in place.
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
Maintains light output and prevents carbide deposition on the LED's surface, ensuring stable performance over time without impairing electrical characteristics.
Implementation Method 1
an enclosed gas containing oxygen gas... prevents carbide deposition on the LED's surface
Implementation Method 2
a lid member that covers the LED, defines a space filled with the enclosed gas, transmits the ultraviolet light emitted from the LED
Implementation Method 3
a substrate that is hermetic to the enclosed gas
Data Source
AI summary
A light-emitting device includes an ultraviolet light LED sealed in a package. The LED is bonded to a substrate with an alloy bonding material. The LED is covered with an enclosed gas containing oxygen gas and further covered with a lid member that is hermetically bonded to the substrate. The lid member defines a space filled with the enclosed gas and constitutes the package. The lid member transmits the ultraviolet light emitted from the LED.