Angled LED Chip Mounting for Light Extraction
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Solution Overview
Problem
Conventional LED packages suffer from significant light loss due to the non-directional and non-uniform emission of light, which is exacerbated by the need for reflective mirrors that cause multiple reflections, resulting in 16-27% light loss as photons reflect 8-9 times before exiting the LED chip.
Innovation Solution
The LED chips are mounted such that the active region is angled relative to the submount, reducing the surface area facing the mounting surface and eliminating the need for a traditional mirror, allowing light to exit from both sides with fewer reflections, thereby improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If LED chips are mounted with large top and bottom surfaces facing the mounting surface, then mechanical stability is improved, but light extraction efficiency deteriorates due to multiple reflections (9 bounces, 16-27% light loss)
Solution Approach 1:
The patent inverts the conventional mounting orientation by mounting the LED chip on its side surface rather than its top or bottom surface. This inversion changes the light extraction path from multiple bounces through the chip to a more direct path, reducing reflections from 9 bounces to fewer reflections and improving light extraction efficiency from 82% to 94%.
Solution Approach 2:
The patent transitions from mounting the LED chip in the traditional planar orientation (top/bottom surfaces facing the mounting surface) to a side-mounted orientation. This dimensional change in mounting configuration allows light to exit from both sides of the chip with fewer reflections, resolving the contradiction between mechanical stability and light extraction efficiency.
2Ease of manufacture
If conventional mounting with large surfaces facing the submount is used, then ease of manufacture is improved, but light loss increases due to required reflective mirrors causing 16-27% light loss
Solution Approach 1:
The patent extracts and eliminates the reflective mirror component from the LED package by changing the mounting orientation. The side-mounted configuration allows light to exit directly from both sides of the chip without requiring additional reflective surfaces, thereby removing the source of multiple reflections and light loss while simplifying the overall package structure.
3Ease of operation
If traditional mirror configuration is used to reflect light, then light directionality is improved, but device complexity increases due to additional reflective components
Solution Approach 1:
The patent removes the reflective mirror component entirely by adopting a side-mounted LED chip configuration. This extraction of the mirror component simplifies the package structure while maintaining light directionality control through the geometric arrangement of the mounted chip, thereby reducing device complexity.
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 configuration enhances light extraction from 82% to 94%, reducing total light loss from 16-27% to 6-9%, and allows for the production of high voltage, wire-bond-free LED chips with increased quantum efficiency and better area utilization.
Implementation Method 1
Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light and generally comprise an active region of semiconductor material sandwiched between two oppositely doped layers of semiconductor material. When a bias is applied across the doped layers, holes and electrons are injected into the active region where they recombine to generate light.
Implementation Method 2
The reflective cup 13 can be filled with an encapsulant material 16 which can contain a wavelength conversion material such as a phosphor. Light emitted by the LED at a first wavelength can be absorbed by the phosphor, which can responsively emit light at a second wavelength.
Data Source
AI summary
A light emitting device and method of fabricating the same is disclosed that comprises at least one light emitter comprising an active region which emits light. The device further comprising a submount arranged such that the at least one light emitter is mounted to the submount such that the active region is angled in relation to the submount.