UV LED Package Venting and Shielding for Epoxy Reliability
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Solution Overview
Problem
Conventional packaging for UV LEDs is prone to deterioration due to the highly energetic UV light emitted, leading to material degradation and reliability issues, as the UV light can attack and degrade materials used in the packaging, affecting the integrity and lifespan of the device.
Innovation Solution
The packaging is designed with a vent to allow gaseous by-products of epoxy degradation to escape, and UV-opaque materials or shields are used to prevent UV light from reaching sensitive components, such as epoxy and voltage regulators, thereby reducing degradation and ensuring high reliability and long lifetime of UV light-emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealed packaging is used for UV LEDs, then the device is protected against environmental contamination, but the epoxy materials within the package deteriorate due to UV light exposure, reducing device reliability
Solution Approach 1:
A UV-opaque encapsulant material is introduced as an intermediary between the UV LED chip and the epoxy materials. This encapsulant blocks UV light from reaching the epoxy, preventing photo-degradation while allowing the package to remain sealed for environmental protection. The encapsulant acts as a mediator that protects the epoxy without compromising the sealing function.
Solution Approach 2:
The package is segmented into distinct functional regions: a UV-opaque encapsulant region that shields UV light, and a transparent lid region that allows UV light emission. This segmentation enables different parts of the package to have different optical properties, with the encapsulant protecting epoxy materials while the transparent lid maintains the sealing function.
2Reliability
If UV-opaque encapsulant material is added to block UV light from epoxy, then epoxy degradation is prevented, but package complexity increases
Solution Approach 1:
The UV-opaque encapsulant material combines multiple functions: it serves as both the protective coating for the UV LED chip and the UV-blocking barrier for the epoxy materials. By merging these functions into a single material layer, the package structure remains relatively simple while achieving both UV protection and epoxy preservation.
Solution Approach 2:
The UV-opaque encapsulant material performs multiple roles simultaneously: it protects the UV LED chip, blocks UV light from reaching epoxy materials, and maintains the sealed environment. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in package complexity.
3Stability of the object's composition
If transparent lid is used to seal the package, then environmental protection is maintained, but UV light propagates to and degrades the epoxy sealing material
Solution Approach 1:
The UV-opaque encapsulant material serves as an intermediary barrier between the UV light source and the epoxy sealing material. It allows the transparent lid to maintain its sealing function while preventing UV light from reaching the epoxy, thus protecting the sealing integrity without compromising environmental protection.
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 UV-induced degradation, enhancing the reliability and longevity of UV light-emitting devices by allowing gas exchange and using UV-opaque materials to block UV light from reaching critical components, resulting in high output power and long-lasting packaged UV LEDs.
Implementation Method 1
UV light from the light-emitter is prevented from propagating to, and therefore causing degradation of, the epoxy utilized to attach the lid to the package
Implementation Method 2
an 'opaque' material substantially does not transmit light of a particular wavelength or wavelength range (e.g., UV light), and instead is reflective and/or strongly absorptive
Implementation Method 3
the package is vented in order to provide an outlet for gaseous by-products of the degradation of the epoxy
Data Source
AI summary
In various embodiments, degradation of epoxy within packages for ultraviolet light-emitting devices is reduced or substantially eliminated via package venting, prevention of transmission of ultraviolet light to one or more regions of epoxy utilized in the package, and/or utilization of packaging schemes that reduce or avoid utilization of epoxy and/or specific metals.