Wavelength Conversion Member With Thermally Conductive Filler
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Solution Overview
Problem
High-power LEDs and LDs cause temperature quenching in wavelength conversion members, leading to decreased luminescence intensity and potential melting of component materials, especially due to heat and high-energy light emission.
Innovation Solution
A wavelength conversion member composed of phosphor powder and thermally conductive filler dispersed in an inorganic binder with a refractive index difference of 0.2 or less, where the thermally conductive filler is predominantly used to efficiently dissipate heat and reduce light scattering, thereby maintaining luminescence intensity and preventing material melting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power of LED or LD is increased to provide higher power, then the excitation light intensity is improved, but the temperature of the wavelength conversion member rises causing luminescence intensity to decrease with time
Solution Approach 1:
A heat dissipation layer is introduced as an intermediary between the wavelength conversion member and the substrate. This layer has higher thermal conductivity than both the wavelength conversion member and the substrate, serving as a thermal bridge to efficiently conduct heat away from the wavelength conversion member, thereby reducing temperature rise and maintaining luminescence intensity under high-power excitation
Solution Approach 2:
The wavelength conversion member itself is designed as a composite material consisting of phosphor particles dispersed in a resin matrix. This composite structure allows optimization of both optical properties (through phosphor selection) and thermal properties (through resin selection), balancing light conversion efficiency with heat dissipation capability
2Power
If the power of LED or LD is increased to provide higher power, then the excitation light intensity is improved, but the temperature rise becomes significant causing component materials to melt
Solution Approach 1:
The heat dissipation layer acts as a thermal intermediary with superior thermal conductivity, positioned between the wavelength conversion member and the substrate. It efficiently conducts heat away from the wavelength conversion member, preventing significant temperature rise that would otherwise cause melting of component materials
Solution Approach 2:
The thermal conductivity parameter of the system is improved by introducing the heat dissipation layer. This changes the thermal transport characteristics, enabling the system to handle higher power densities without reaching melting temperatures of the phosphor or resin materials
3Ease of manufacture
If a resin matrix is used in the wavelength conversion member, then the manufacturing ease is improved, but the resin is degraded by light from the excitation light source causing discoloration or deformation
Solution Approach 1:
Instead of using organic resin materials, the invention uses inorganic materials (such as glass or ceramic matrices) to replace the resin. This substitution maintains the ability to form a matrix structure for phosphor dispersion while eliminating the light degradation and discoloration issues inherent to organic resins under high-energy excitation light
Solution Approach 2:
The material composition parameter is changed from organic resin to inorganic matrix materials. This fundamental material substitution preserves the manufacturing advantages of having a binder matrix while dramatically improving resistance to light-induced degradation, discoloration, and deformation under high-power excitation
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 luminescence intensity degradation and prevents material melting by enhancing thermal conductivity and light extraction efficiency, ensuring stable performance under high-power excitation light conditions.
Implementation Method 1
heat of excitation light itself and heat generated from the phosphor powder when the wavelength conversion member is irradiated with the excitation light transmit through the thermally conductive filler and is efficiently released to the outside
Implementation Method 2
light scattering due to reflection at the interface between the thermally conductive filler and the inorganic binder
Implementation Method 3
a wavelength conversion member in which a phosphor powder is dispersed in a resin matrix... absorbs part of the light from the LED to convert it to a yellow light
Data Source
AI summary
Provided are: a wavelength conversion member capable of reducing the decrease in luminescence intensity with time and the melting of component materials when irradiated with high-power excitation light; a method for manufacturing the same; and a light-emitting device using the wavelength conversion member. A wavelength conversion member 10 is made of a phosphor powder 2 and a thermally conductive filler 3 both dispersed into an inorganic binder 1, a refractive index difference between the inorganic binder 1 and the thermally conductive filler 3 being 0.2 or less, a volume ratio of a content of the inorganic binder 1 to a content of the thermally conductive filler 3 being 40:60 to 5:95.