LED Substrate TIR Dielectric Ring for Light Extraction
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Solution Overview
Problem
Conventional LED packaging techniques suffer from light absorption and scattering due to the use of metal reflective rings, which are complex to form and costly, and do not achieve 100% light reflection efficiency.
Innovation Solution
A dielectric ring utilizing total internal reflection (TIR) is employed, with a low-index material having good adhesion to the substrate and lens, extending beyond the lens edge to ensure 100% reflection, or an air layer is formed to create a TIR interface, eliminating edge scattering and electrode misalignment concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metal reflective ring is used to reflect light, then light reflection efficiency is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the metal reflective ring with a dielectric mirror structure that uses total internal reflection instead of metallic reflection. This substitution eliminates the need for complex metal deposition processes while achieving superior light reflection efficiency through optical physics principles
Solution Approach 2:
The patent changes the refractive index parameter by introducing a low-index dielectric material layer, creating the conditions for total internal reflection at the dielectric-lens interface. This parameter change enables 100% reflection efficiency without the manufacturing complexity of metal rings
2Loss of energy
If a metal reflective ring is used to reflect light, then light reflection is achieved, but light scattering and absorption occur at the edge
Solution Approach 1:
The patent extends the dielectric material layer beyond the lens edge in the radial dimension, creating a continuous optical interface that eliminates edge scattering. This dimensional extension ensures that all light rays, including those at extreme angles, encounter the TIR interface before reaching the lens edge
Solution Approach 2:
The patent converts the previously harmful edge effect into a beneficial extended TIR interface. By extending the dielectric layer beyond the lens edge, the structure that could have caused scattering now provides additional reflection opportunities for oblique light rays
3Loss of energy
If a metal reflective ring is used, then light reflection is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive metal reflective materials with inexpensive dielectric materials that can be applied through standard semiconductor fabrication processes. The dielectric mirror structure achieves superior performance at lower material and manufacturing costs
4Reliability
If the ring material ends prior to the lens edge to ensure hermetic seal, then sealing is improved, but light scattering and absorption increase
Solution Approach 1:
The dielectric material layer acts as an intermediary optical element that extends beyond the lens edge, providing a continuous reflection interface. This intermediary structure eliminates the gap between the reflective element and lens edge, preventing light scattering while maintaining hermetic sealing capabilities
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 achieves maximum light reflection with no edge scattering, reducing costs and improving light extraction efficiency while being simpler to implement than metal reflective rings.
Implementation Method 1
a dielectric ring using total internal reflection (TIR) is used. With TIR, there is 100% reflection
Implementation Method 2
Any phosphor or LED light impinging on the interface of the lens and the low-index material at greater than the critical angle reflects off the interface with substantially 100% reflectance
Data Source
Figure 1~2
Figure 3~4
AI summary
A packaged LED module includes an LED die mounted on a substrate surface. Formed on the substrate surface and surrounding the die is a first layer of a low index of refraction material. A lens of a higher index of refraction material is molded over the LED die and the first layer. The interface of the lens and the first layer reflects light by total internal reflection (TIR), in accordance with Snell's Law, when the LED light impinges at greater than the critical angle. The first layer may be a low index epoxy, silicone, or other material. In another embodiment, a layer surrounding the LED die is processed after the lens is formed to create an air/lens interface for TIR. The LED die may include a phosphor layer, which results in even more side light being reflected off the interface and not absorbed by the substrate surface.