Selective Reflective Coating for LED Substrates via Bond Strength
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Solution Overview
Problem
Existing methods for providing a reflective coating to LED substrates are complex, time-consuming, and compromise between thermal conductivity and light reflectivity, as they often require chemical mechanical polishing and alignment of masks, which are cumbersome and prone to contamination.
Innovation Solution
A method involving a substrate with distinct surface materials, where a reflective compound forms a stronger bond with one surface material than the other, allowing for self-developing patterning through mechanical treatment after partial curing, using a sol-gel binder with hydrolyzed silane monomers to create a reflective coating that adheres better to ceramic than metal surfaces, optimizing thermal conductivity and reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the porosity of the ceramic is increased to improve light reflectivity, then the light reflectivity is improved, but the thermal conductivity is considerably reduced
Solution Approach 1:
The substrate is designed with different surface materials in different regions: a first surface portion with ceramic material for thermal management and a second surface portion with metal material for electrical connections. This local differentiation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The substrate surface is segmented into distinct functional zones with different materials (ceramic and metal), allowing the reflective coating to be selectively applied only to the ceramic portion where reflectivity is needed, while the metal portion remains exposed for its electrical and thermal functions.
2Manufacturing precision
If a mask is used to protect electrodes during reflective coating application, then the reflective coating is applied only to desired areas, but the process becomes complicated and time consuming
Solution Approach 1:
The substrate is pre-configured with distinct surface materials (ceramic and metal) in specific patterns before coating application. This preliminary structuring eliminates the need for masks during coating, as the material differences themselves guide selective coating adhesion and removal.
Solution Approach 2:
The different surface materials self-differentiate during the coating process: the reflective coating naturally adheres to the ceramic surface while being easily removed from the metal surface, allowing the substrate materials themselves to guide the coating pattern without external masking.
3Manufacturing precision
If chemical mechanical polishing is used to remove coating from metal surfaces, then the coating is removed from electrodes, but the process is time consuming and prone to contamination
Solution Approach 1:
The mechanical chemical mechanical polishing process is replaced with a simpler mechanical treatment that exploits the inherent differences in coating adhesion to ceramic versus metal surfaces. The coating is removed from metal areas through less intensive mechanical means, reducing time and contamination risk.
Solution Approach 2:
The treatment intensity for removing coating from metal surfaces is optimized to be less intensive than chemical mechanical polishing. By adjusting the mechanical treatment parameters, the coating is effectively removed from metal areas while preserving the coating on ceramic areas, reducing processing time and contamination.
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 method simplifies the application of a reflective coating, reduces contamination risks, and enhances light-output efficiency by ensuring a strong bond on the ceramic surface while easily removing the coating from metal surfaces, thus improving the reliability and thermal management of LED packages.
Implementation Method 1
applying a reflective compound configured to attach to the first surface material to form a bond with the substrate in the first surface portion that is stronger than a bond between the reflective compound and the substrate in the second surface portion
Implementation Method 2
using a sol-gel binder with hydrolyzed silane monomers to create a reflective coating that adheres better to ceramic than metal surfaces
Implementation Method 3
The reflective coating is advantageous for enhancing the light-output of the LED package reducing light losses in the parts covered by the reflector
Implementation Method 4
The mounting substrate is often of a high density polycrystalline ceramic having a relatively high thermal conductivity
Data Source
AI summary
The present invention relates to a method for providing a reflective coating (114) to a substrate (104) for a light-emitting device (112), comprising the steps of: providing (201) a substrate (104) having a first surface portion (116) with a first surface material and a second surface portion (106, 108) with a second surface material different from the first surface material; applying (202) a reflective compound (401) configured to attach to said first surface material to form a bond with the substrate (104) in the first surface portion (116) that is stronger than a bond between the reflective compound (401) and the substrate (104) in the second surface portion (106, 108); curing (203) said reflective compound (401) to form a reflective coating (114) having said bond between the reflective coating (114) and the substrate (104) in the first surface portion (116); and subjecting said substrate (104) to a mechanical treatment with such an intensity as to remove (205) said reflective coating (114) from said second surface portion (106, 108) while said reflective coating (114) remains on said first surface portion (116).