Light Emitting Device Heat Spreading and Insulation
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Solution Overview
Problem
Conventional light emitting devices face challenges in achieving both good heat dissipation and dielectric strength, especially at high output levels, due to limitations in thermal conductivity and creepage distance, which affect efficiency and service life, and result in larger, less compact designs.
Innovation Solution
A light emitting device configuration featuring a heat spreading member mounted with light emitting elements and an insulating member with a recess portion, allowing for efficient heat dissipation and dielectric strength, using materials with high thermal conductivity and dielectric strength, such as aluminum or ceramic, to ensure effective heat management and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating sheet is sandwiched at the rear face of the light emitting device to ensure good dielectric strength, then dielectric strength is improved, but heat dissipation performance suffers
Solution Approach 1:
The insulating structure is segmented into multiple layers: a first insulating layer between the light emitting element and the heat dissipation fin, and a second insulating layer between the heat dissipation fin and the substrate. This segmentation allows each layer to be optimized for its specific function, with the first layer providing electrical insulation and the second layer providing mechanical support and additional insulation, thereby maintaining both dielectric strength and heat dissipation performance
Solution Approach 2:
A heat dissipation fin is introduced as an intermediary component between the light emitting element and the substrate. This fin serves multiple functions: it provides a thermal conduction path for heat dissipation, acts as an insulating barrier to prevent direct thermal contact with the substrate, and provides mechanical support. The fin resolves the contradiction by mediating between the light emitting element and the substrate, allowing both dielectric strength and heat dissipation to be achieved simultaneously
2Reliability
If the sheet surface area is made large enough to achieve adequate creepage distance to the end of the metal substrate, then dielectric strength is improved, but device compactness is hampered
Solution Approach 1:
The creepage distance is extended by utilizing the vertical dimension through the heat dissipation fin structure. Instead of requiring a large horizontal surface area, the insulating layers wrap around the fin, providing creepage distance in both the horizontal and vertical directions. This dimensional transition allows adequate insulation with a more compact footprint
Solution Approach 2:
The insulating layers are nested around the heat dissipation fin, with the first insulating layer positioned between the light emitting element and the fin, and the second insulating layer positioned between the fin and the substrate. This nested configuration maximizes the use of available space while maintaining adequate creepage distance, achieving compactness without compromising dielectric strength
3Reliability
If ceramic substrate package with high dielectric strength is used, then dielectric strength is improved, but thermal conductivity decreases causing heat to become trapped inside the light emitting device
Solution Approach 1:
The device employs a composite structure combining different materials with complementary properties: the substrate provides high dielectric strength, while the heat dissipation fin (made of metal or thermally conductive material) provides high thermal conductivity. The insulating layers are positioned strategically to maintain dielectric isolation while allowing thermal conduction paths, creating a composite system that achieves both high dielectric strength and good thermal management
Solution Approach 2:
The thermal management function is segmented from the dielectric function. The substrate is dedicated to providing dielectric strength, while the heat dissipation fin is dedicated to providing thermal conduction. By separating these functions into different components rather than relying on a single material to perform both functions, the design achieves both high dielectric strength and good thermal conductivity simultaneously
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 enables both effective heat dissipation and dielectric strength, even at high output levels, by optimizing the thermal conductivity and dielectric properties of the materials used, resulting in improved efficiency and extended service life while maintaining a compact design.
Implementation Method 1
heat spreading member on which the plurality of light emitting elements are mounted
Implementation Method 2
insulating member having a recess portion that includes side walls and a bottom wall, a top face of the bottom wall being in contact with the bottom face of the heat spreading member
Data Source
AI summary
A light emitting device has a plurality of light emitting elements, a heat spreading member on which the plurality of light emitting elements are mounted, and having a bottom face, an insulating member having a recess that includes side walls and a bottom wall, a top face of the bottom wall being in contact with the bottom face of the heat spreading member, and a circuit board having a circuit that is provided on the heat spreading member and supplies power to the plurality of light emitting elements.