Patterned Lumiramic Oxygen Channels for PCLED Adhesive Stability
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Solution Overview
Problem
Phosphor-converted LEDs (pcLEDs) experience transient and permanent degradation due to adhesive bond issues, particularly related to oxygen diffusion and thermal quenching, which affects their stability and efficiency.
Innovation Solution
Patterned ceramic wavelength-converting phosphor structures (lumiramics) with enhanced oxygen permeability features, such as holes and channels, are bonded to LEDs to improve adhesive bond quality and reduce degradation, while maintaining thermal pathways through a thin adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thin adhesive layer is used to maintain thermal pathways, then thermal management is improved, but oxygen diffusion is insufficient causing adhesive degradation
Solution Approach 1:
The lumiramic is designed with a porous structure containing multiple channels that extend from the first surface to the second surface. These channels allow oxygen to diffuse through the lumiramic and reach the adhesive bond region, preventing adhesive degradation while maintaining a thin overall structure for effective thermal management.
Solution Approach 2:
The lumiramic is segmented into multiple functional regions: phosphor-containing regions for wavelength conversion, channel regions for oxygen transport, and adhesive bond regions. This segmentation allows each region to perform its specific function optimally - phosphors convert light, channels transport oxygen, and the thin adhesive layer maintains thermal pathways.
2Reliability
If oxygen permeability is enhanced to prevent adhesive degradation, then reliability is improved, but thermal pathways may be disrupted
Solution Approach 1:
Different regions of the lumiramic have different properties: phosphor-containing regions are optimized for light conversion, while channel regions are optimized for oxygen transport. The channels are strategically positioned to provide oxygen permeability without disrupting the overall thermal pathways, as the thin adhesive layer still maintains thermal contact between the LED and heat sink.
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 reduces transient degradation and maintains conversion efficiency by enhancing oxygen diffusion and thermal management, as demonstrated by the comparison of patterned and unpatterned lumiramic pcLEDs, where the patterned lumiramic pcLEDs show no transient degradation and improved stability over time.
Implementation Method 1
LEDs may be combined with one or more wavelength converting materials (generally referred to herein as "phosphors") that absorb light emitted by the LED and in response emit light of a longer wavelength
Implementation Method 2
The enhanced oxygen permeability reduces transient degradation of the pcLED occurring in the region of the adhesive bond
Data Source
AI summary
Patterned ceramic wavelength-converting phosphor structures may be bonded to an LED to form a pcLED. The phosphor structures are patterned with features that provide enhanced oxygen permeability to an adhesive bond used to attach the phosphor structure to the LED. The enhanced oxygen permeability reduces transient degradation of the pcLED occurring in the region of the adhesive bond.