Dual Reflecting Layer Layout for LED Package Light Extraction
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Solution Overview
Problem
Existing methods for manufacturing light emitting devices with reflecting materials face challenges in achieving continuous coverage from the bottom surface to the upper edges of lateral surfaces, leading to potential inefficiencies in light emission.
Innovation Solution
A method involving the sequential formation of first and second reflecting layers using resins with reflecting materials, where the second reflecting layer is applied under centrifugal force to ensure coverage of the bottom surface without contacting the lateral surfaces, and a phosphor-containing layer is added for enhanced light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a first resin containing reflecting material is injected into the recess and centrifugal force is applied to form a reflecting layer, then the reflecting material can be localized near the bottom surface and lateral surfaces, but high precision adjustment is required and there is a possibility that the reflecting material layer is not continuously disposed from the bottom surface to the upper edges of the lateral surfaces
Solution Approach 1:
The reflecting layer is divided into two separate layers: a first reflecting layer formed by injecting first resin containing first reflecting material and applying centrifugal force to cover lateral surfaces, and a second reflecting layer formed by injecting second resin containing second reflecting material and applying centrifugal force to cover the bottom surface. This segmentation allows each layer to be optimized for its specific function and position, ensuring continuous coverage without requiring high precision adjustment of a single layer.
Solution Approach 2:
The patent applies centrifugal force in different dimensional orientations for each reflecting layer. The first reflecting layer is formed by applying centrifugal force about an axis with lateral surfaces positioned outward, while the second reflecting layer is formed by applying centrifugal force about an axis with the bottom surface positioned outward. This dimensional change in the application of centrifugal force enables precise control over material distribution in different spatial dimensions, ensuring continuous coverage.
2Productivity
If the second reflecting layer is formed to cover the bottom surface, then light extraction efficiency is improved, but the reflecting material may contact the lateral surfaces of the light emitting element causing light absorption
Solution Approach 1:
The second reflecting layer is designed with non-uniform thickness, being thicker at the center portion and thinner at the peripheral portion. This local quality variation ensures that the reflecting material covers the bottom surface effectively for light extraction while preventing contact with the lateral surfaces of the light emitting element, thus avoiding light absorption losses.
Solution Approach 2:
The patent changes the thickness parameter of the second reflecting layer across different locations. By controlling the thickness to be greater at the center and smaller at the periphery, the design optimizes light extraction efficiency at the bottom surface while preventing the reflecting material from reaching and absorbing light from the lateral surfaces of the 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
This approach results in high emission efficiency by preventing light leakage and absorption, improving light extraction and color distribution, while maintaining precise control over the reflecting material placement.
Implementation Method 1
settling the second reflecting material in the second resin by a centrifugal force
Implementation Method 2
forming a first reflecting layer by covering lateral surfaces of the recess with a first resin containing a first reflecting material; forming a second reflecting layer by covering the bottom surface in the recess with a second resin containing a second reflecting material
Implementation Method 3
disposing a phosphor-containing layer, in which a third resin contains a phosphor, on the second reflecting layer and the light emitting element
Data Source
AI summary
A light emitting device includes: a package having an upper surface defining a recess; a light emitting element and a protection device respectively disposed on a bottom surface of the recess; a first reflecting layer covering a lateral surface of the recess; and a second reflecting layer covering the bottom surface of the recess. The first reflecting layer is apart from the light emitting element and covers the protection device. The second reflecting layer contacts with a lower portion of a lateral surface of the light emitting element. An upper surface of the light emitting element and an upper portion of the lateral surface of the light emitting element are exposed from the second reflecting layer.