Non-yellowing Silicone Reflective Layer for LED Substrates
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) suffer from non-directional and non-uniform light emission, leading to reduced optical efficiency due to back-emission and scattering from light diffusion lenses and phosphor particles, and existing reflective materials degrade over time, especially when exposed to blue light.
Innovation Solution
A light emitting device with a substrate coated by a stable, non-yellowing reflective layer comprising a silicone carrier with dispersed reflective particles, which effectively redirects back-emitted and scattered light, maintaining reflectivity and emission efficiency over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If epoxy-based reflective materials are used in PCB and substrate technology, then light reflection and redirection is achieved, but the materials yellow during prolonged use and degrade in the presence of blue light
Solution Approach 1:
The patent changes the material parameters by transitioning from epoxy-based reflective materials to silicone-based materials. This parameter change fundamentally alters the chemical composition and properties, making the material resistant to yellowing and degradation from blue light exposure while maintaining reflective capabilities.
Solution Approach 2:
The invention uses composite materials by combining silicone as the base material with specific additives and formulations. This composite approach creates a reflective material that maintains optical properties while achieving superior durability and resistance to environmental degradation compared to conventional epoxy-based materials.
2Illumination intensity
If light diffusion lenses, light scattering particles, and phosphor particles are disposed over the chip(s) to achieve more uniform light emission, then light uniformity is improved, but a fraction of brightness is lost due to back-emission, scattering and back-reflection
Solution Approach 1:
The patent converts the harmful back-emitted and scattered light into beneficial light output by using reflective materials to redirect these photons. Instead of allowing the scattered light to be lost, the reflective substrate captures and redirects it toward the viewing direction, transforming energy loss into useful light output.
Solution Approach 2:
The invention utilizes materials with specific optical properties that affect light color and direction. The reflective materials are designed to maintain color fidelity while redirecting light, and the silicone material itself has optical properties that enhance light extraction and reduce wavelength-dependent losses.
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 enhances light output by redirecting scattered light, improving luminous flux and color mixing, with the reflective coating remaining stable and resistant to discoloration, even under prolonged use and adverse conditions.
Implementation Method 1
reflective materials have been disposed on the substrate of various light emitting devices. The reflective layer is substantially non-yellowing
Implementation Method 2
The reflective coating can comprise a silicone carrier with light reflective particles dispersed in the carrier
Data Source
AI summary
Apparatuses and methods for producing light emitting devices maximizing luminous flux output are disclosed. In one possible embodiment, a light emitting device comprises a substrate and a reflective layer at least partially covering the substrate. The reflective layer is non-yellowing, and may be substantially light transparent. One or more light emitting diode (LED) chips are disposed on the substrate. The light emitting device may emit white light. The reflective layer may comprise a silicone carrier with light reflective particles dispersed in the silicone carrier. A light diffusion lens may also be disposed on the substrate and surrounding the LED chips. Furthermore, one or more microspheres, light scattering particles, and/or phosphor particles may be dispersed in the lens. In one possible method for producing a light emitting device, a substrate is provided. One or more LED chips are coupled with the substrate, and a high reflective, non-yellowing coating is applied on at least a portion of the top surface of the substrate. The coating comprises a carrier with reflective particles dispersed throughout.