Inverted Cone Package Structure for Light Extraction
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Solution Overview
Problem
Light-emitting devices with flip-chip structures face low light extraction efficiency due to difficulty in guiding light emitted from the lateral side of the chip, and existing solutions like substrate lift-off or wavelength conversion films are costly and have limited heat resistance, making them unsuitable for high power applications.
Innovation Solution
A light-emitting device with a package structure featuring an inward recessed groove where the width decreases from the light exiting surface to the rear surface and the groove width increases from inside to outside, enhancing light extraction efficiency and reliability under high power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If substrate lift-off or surface roughening is adopted to guide light from the lateral side, then light extraction efficiency is improved, but manufacturing cost increases and heat resistance is limited
Solution Approach 1:
The patent transitions from planar light extraction to three-dimensional light guidance by creating an inverted cone structure with specific angular geometry. The cone angle of 60-80 degrees enables light to be guided through the lateral side of the chip and extracted from the bottom surface, utilizing spatial dimensionality to improve extraction efficiency without requiring costly substrate lift-off processes
Solution Approach 2:
The package structure employs asymmetric design with an inverted cone configuration that is tilted at 10-30 degrees relative to the vertical axis. This asymmetric geometry creates favorable light extraction paths while maintaining structural integrity and heat dissipation capabilities, avoiding the need for symmetric but costly solutions like complete substrate removal
2Illumination intensity
If wavelength conversion film is provided between lateral side and reflective structure, then light extraction is enhanced, but heat resistance is limited and light decay increases at high power density
Solution Approach 1:
The patent extracts the wavelength conversion function from a separate film layer and integrates it directly into the inverted cone package structure. The conversion material is positioned within the cone geometry itself, eliminating the need for additional films that would have limited heat resistance, while the tilted asymmetric structure provides favorable light extraction paths
Solution Approach 2:
The patent uses composite material structures where the inverted cone package combines reflective materials, wavelength conversion materials, and transparent encapsulants in a integrated geometry. This composite approach enables simultaneous achievement of light extraction enhancement and heat resistance without relying on separate films with limited thermal stability
3Ease of manufacture
If conventional package structure is used, then manufacturing is simple, but light extraction efficiency from lateral side is low
Solution Approach 1:
The patent introduces three-dimensional inverted cone geometry with 60-80 degree cone angles into the package structure, enabling light to be guided through the lateral side and extracted from the bottom surface. This dimensional transformation significantly improves light extraction efficiency while maintaining compatibility with conventional manufacturing processes through additive or integrated fabrication approaches
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 structural design increases light extraction efficiency and brightness by up to 14% compared to conventional structures, while maintaining reliability under high temperature and humidity conditions, with improved angular color uniformity and reduced light decay.
Implementation Method 1
the light emitted from the lateral side of the chip structure cannot be guided out easily
Implementation Method 2
the width of the package structure gradually decreases from a light exiting surface to a rear surface
Data Source
AI summary
A light-emitting device includes a package structure and a light-emitting chip. The package structure has a light exiting surface, a rear surface facing away from the light exiting surface, a groove inward recessed on the rear surface, and an outer surrounding side wall surrounding the groove. The light-emitting chip is disposed in the groove. The width of the package structure gradually decreases from the light exiting surface to the rear surface. The width of the groove gradually increases from inside to outside of the groove.