LED Chip Package With Graded Refractive Index Optical Layer
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Solution Overview
Problem
Existing light-emitting diode chips suffer from low light extraction efficiency due to total reflection at the light-emitting surface.
Innovation Solution
A chip package design incorporating an optical layer with a graded refractive index, fluorescence powder for color conversion, scattering particles for light homogenization, and a metal reflection cup to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional light-emitting diode chip structure is used, then the device is simple to manufacture, but light extraction efficiency is low due to total reflection at the light-emitting surface
Solution Approach 1:
An optical layer with graded refractive index is introduced as an intermediary between the light-emitting diode chip and the external environment. This optical layer gradually transitions the refractive index from the high-index chip material to the lower-index external medium, eliminating abrupt refractive index mismatches that cause total internal reflection, thereby significantly improving light extraction efficiency while maintaining manufacturing simplicity
Solution Approach 2:
The refractive index parameter of the optical layer is designed to gradually change from the chip interface toward the external surface. This continuous parameter variation allows light rays to progressively adapt to the refractive index difference, preventing total internal reflection and enhancing light extraction without complicating the manufacturing process
2Illumination intensity
If the refractive index of the optical layer is uniformly high, then light concentration is improved, but total reflection at the interface increases
Solution Approach 1:
The refractive index of the optical layer is designed to gradually change from a higher value near the chip interface to a lower value toward the external surface. This gradient profile allows the optical layer to simultaneously achieve light concentration near the chip while reducing total reflection at the interface, optimizing both illumination intensity and light extraction efficiency
3Use of energy by moving object
If fluorescence powder with large particle size is used, then color conversion efficiency is improved, but light scattering and homogenization are reduced
Solution Approach 1:
The optical layer is designed with spatially varying properties: fluorescence powder with larger particle sizes is positioned in regions where color conversion is prioritized, while areas requiring better light homogenization incorporate smaller particles or different distributions. This local optimization allows simultaneous achievement of high color conversion efficiency and improved light homogenization throughout the optical layer
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 enhances light extraction efficiency by minimizing total reflection and improving light concentration, resulting in improved light emission intensity.
Implementation Method 1
A refractive index of the optical layer gradually decreases along the stacking direction
Implementation Method 2
Existing light-emitting diode chips are prone to total reflection at the light-emitting surface of the chip
Implementation Method 3
the chip package further includes fluorescence powder, disposed in the optical layer
Implementation Method 4
the chip package further includes a plurality of scattering particles, disposed in the optical layer
Implementation Method 5
the chip package further includes a metal reflection layer, disposed on a surface of the insulation structure facing the light-emitting diode chip and the optical layer
Data Source
AI summary
A chip package includes a substrate, a light-emitting diode chip, and an optical layer. The light-emitting diode chip is disposed on the substrate along a stacking direction. The optical layer is disposed on the light-emitting diode chip along the stacking direction. A refractive index of the optical layer gradually decreases along the stacking direction.