UV Light Transmitting Cap Seal for Hermetic LED Packages
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Solution Overview
Problem
Semiconductor light emitting devices, particularly those emitting ultraviolet light, face challenges with insufficient hermeticity when exposed to humid environments, leading to deterioration due to moisture susceptibility, especially with AlGaN-based elements, and issues with glass substrates having low adhesiveness with metal.
Innovation Solution
A semiconductor light emitting device design featuring a substrate with an annular metal layer and a light transmitting cap with a ceramic and metal flange fixation layer, providing high hermeticity through a ceramic layer welded to the flange and a metal layer, which enhances bonding with glass and improves environmental resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If glass with high purity and hardness is used for ultraviolet transmission, then light transmission is improved, but adhesiveness with metal is reduced
Solution Approach 1:
The ceramic layer serves as an intermediary between the metal bonding material and the high-purity glass. This intermediate layer improves the adhesiveness between metal and glass without compromising the ultraviolet light transmission properties of the glass. The ceramic layer acts as a bridge that enables reliable bonding while maintaining the optical performance of the glass cap.
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 achieves high reliability and environmental resistance, maintaining hermeticity and preventing moisture and corrosion, even in long-term use, by ensuring a strong bond between the substrate and the glass cap, thus protecting the AlGaN-based light emitting elements.
Implementation Method 1
a ceramic layer welded to the flange
Implementation Method 2
a metal layer formed on the ceramic layer... enhances bonding with glass
Data Source
AI summary
A semiconductor light emitting device has: a semiconductor light emitting element; a substrate on which the semiconductor light emitting element is mounted and which includes a substrate bonding surface to which a substrate metal layer having an annular shape is fixed; and a light transmitting cap including a window portion containing glass and transmitting radiation light of the semiconductor light emitting element and a flange having a bottom surface to which an annular flange fixation layer having a size corresponding to the substrate metal layer is fixed, and sealed and bonded to the substrate with a space housing the semiconductor light emitting element by bonding of the flange fixation layer to the substrate metal layer. The flange fixation layer contains a ceramic layer welded to the flange and a metal layer formed on the ceramic layer.