Segmented LED Array with Thermally Conductive Substrate
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Solution Overview
Problem
High power LED light-emitting device arrays face efficiency decreases due to heat generation from phosphor-coated or filled covers, leading to reduced light-conversion efficiency and die efficiency, along with issues like light cross-talk and chemical reactions affecting reliability and production costs.
Innovation Solution
A thermally conductive support member with a phosphor-coated or filled cover attached to its upper face, allowing heat transfer to a thermally conductive substrate, combined with optimized cell design and reflective surfaces to minimize cross-talk and chemical reactions, and controlled phosphor usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphor-coated or filled covers are used to convert monochromatic light to desired light properties, then light conversion efficiency is improved, but heat generation increases causing efficiency decrease and reliability issues
Solution Approach 1:
The patent divides the light-emitting device array into individual cells, each with its own light-emitting die and phosphor coating. This segmentation allows heat to be dissipated at the source (substrate level) rather than concentrated in a single phosphor-coated cover, reducing the temperature rise that causes efficiency degradation while maintaining the light conversion function.
Solution Approach 2:
The patent introduces a thermally conductive substrate as an intermediary between the light-emitting dies and the external environment. This substrate acts as a heat sink that absorbs and dissipates heat generated by the phosphor conversion process, preventing excessive temperature rise that would otherwise reduce light conversion efficiency and reliability.
2Illumination intensity
If multiple light-emitting dies are arranged in a package to increase light intensity, then light intensity is improved, but heat generation and cross-talk increase reducing efficiency
Solution Approach 1:
The patent segments the light-emitting device array into individual cells with physical separations. Each cell contains one or more light-emitting dies with phosphor coating, and the cells are spaced apart to prevent light cross-talk. This segmentation allows high light intensity to be achieved through multiple cells while maintaining efficiency by eliminating cross-talk and distributing heat generation across multiple thermally conductive substrate contact points.
3Use of energy by moving object
If phosphor is applied to covers for light conversion, then desired light properties are achieved, but chemical reactions occur affecting reliability
Solution Approach 1:
The patent extracts the phosphor coating from the cover structure and applies it directly to the light-emitting dies or to the substrate within individual cells. This removes the phosphor from the cover environment where it would be exposed to chemicals and moisture, thereby preventing chemical reactions that would degrade reliability while maintaining the light conversion function.
4Use of energy by moving object
If conventional light-emitting device arrays are used with phosphor-coated covers, then light conversion is achieved, but production costs increase due to reliability issues
Solution Approach 1:
The patent employs a segmented cell structure that can be manufactured using standardized processes. Each cell is a modular unit that can be independently fabricated and then assembled into arrays, enabling economies of scale. The thermally conductive substrate serves as a common platform for all cells, simplifying the manufacturing process compared to conventional approaches requiring separate phosphor-coated covers for each light-emitting element.
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
Enhances heat dissipation, maintains efficiency, reduces light cross-talk, and decreases chemical reactions, thereby improving reliability and production economics while maintaining light quality.
Implementation Method 1
A substantially flat substrate in addition to being a mechanical support for the electrical and optical layers of the light-emitting device is often used as means for heat dissipation from the light-emitting device array
Implementation Method 2
use a phosphor material to convert monochromatic light from a blue or ultra-violet color emitting LED die or dice to a light with the desired properties
Implementation Method 3
phosphor-coated or filled cover attached to its upper face, allowing heat transfer to a thermally conductive substrate
Implementation Method 4
surfaces that are transparent to photons emitted at a particular wavelength or that have poor reflectivity of such photons in an undesirable direction of emission may be treated, e.g., by polishing, buffing, or any other process, to acquire a specific reflectivity
Data Source
AI summary
A light-emitting device and a method for manufacturing the light-emitting device is disclosed. Such a light-emitting device comprises a substrate, a plurality of cells disposed in the substrate, and a plurality of semiconductor dice, wherein each of the plurality of cells accommodates at least one of the plurality of dice. Each of the plurality of cells may be filled with an encapsulant, phosphor or a mixture of an encapsulant with phosphor to control light characteristics of the light-emitting device. In an alternative aspect, cells may be filled with an encapsulant, and comprise a transparent cover coated with or filled with phosphors to control light characteristics of the light-emitting device.