Reflective Layer Surface Roughness for LED Circuit Boards
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Solution Overview
Problem
Current light-emitting devices with LEDs on circuit boards face challenges in enhancing luminous efficiency, particularly in improving the reflectance of the reflective layer to maximize light reflection and minimize diffuse reflection.
Innovation Solution
A circuit board design featuring a reflective layer with specific surface roughness parameters (arithmetic mean roughness Ra < 0.2 μm, Rku/Rsk ratio between 5 and 15, and optimized material proportions) and a substrate with high reflectance, combined with a resin layer for enhanced reflectance, utilizing materials like gold and silver for the reflective layer and ceramic substrates for mechanical strength and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the surface of the reflective layer is made smoother to reduce diffuse reflection, then reflectance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent transforms the manufacturing challenge by defining specific parameter ranges that balance smoothness and manufacturability. By setting Ra ≤ 0.2 μm and 5 ≤ Rku/Rsk ≤ 15, the patent provides clear quantitative targets that guide manufacturing processes. These parameter specifications enable manufacturers to achieve the required surface quality through controlled processing while maintaining feasibility in production, thus resolving the contradiction between smoothness requirements and manufacturing precision.
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 design achieves high reflectance and improved luminous efficiency by suppressing diffuse reflection and promoting total reflection, resulting in a more efficient light-emitting device with enhanced long-term reliability and heat management.
Implementation Method 1
light can be totally reflected easily
Data Source
Figure 1
AI summary
A circuit board of the present disclosure includes a substrate, a conductor layer located on the substrate, a reflective layer located on the conductor layer, and a resin layer located on the substrate to be in contact with the conductor layer and the reflective layer. In a surface of the reflective layer, arithmetic mean roughness Ra obtained from a roughness profile is less than 0.2 µm, and a ratio of kurtosis Rku obtained from a roughness profile to skewness Rsk obtained from a roughness profile is 5 or more and 15 or less.