LED Package Layout for Lower Optical Loss and Corrosion
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Solution Overview
Problem
Conventional LED packages face challenges with optical losses due to internal reflection and corrosion of metal components, which affect light emission efficiency and reliability in various environmental conditions.
Innovation Solution
The LED package design incorporates a submount with a metal pattern, including die attach and bond pads, and features a light-altering material such as fused silica or titanium dioxide particles in silicone to reduce optical losses and corrosion, along with a wavelength conversion element and electrostatic discharge (ESD) chips for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LED packages use metal reflectors to direct light, then light direction control is improved, but optical losses occur due to less than 100% reflectivity
Solution Approach 1:
The patent removes the metal reflector component entirely from the LED package design. Instead of using a separate reflector element, the package utilizes the submount structure itself with optimized geometry and light-altering materials integrated directly into the packaging architecture, eliminating the reflective interface and its associated optical losses.
Solution Approach 2:
The patent employs light-altering materials such as white paint, titanium dioxide, or other high-refractive-index materials applied to the submount surface to achieve light redirection without metal reflection. These composite material solutions provide the necessary optical functionality while avoiding the inherent reflectivity limitations of metal surfaces.
2Reliability
If metal components are used in LED packages for electrical connections, then electrical conductivity is improved, but corrosion occurs in various environmental conditions
Solution Approach 1:
The patent employs composite material structures for electrical connections, such as using solder bumps with protective coatings or multi-layer metal systems (e.g., copper with nickel and gold plating) that combine high conductivity with corrosion resistance. The submount itself may use ceramic or composite materials that are inherently resistant to environmental degradation.
Solution Approach 2:
The patent creates protective environments for metal components through encapsulation materials and sealing structures that isolate electrical connections from corrosive atmospheric elements. The package design incorporates hermetic or semi-hermetic sealing that maintains an inert or controlled environment around sensitive metal interconnects.
3Illumination intensity
If LED packages use conventional encapsulants and reflectors, then light extraction is improved, but internal reflection limits external quantum efficiency
Solution Approach 1:
The patent modifies optical parameters by changing the refractive index matching between components, using encapsulants with refractive indices optimized for minimal internal reflection. The submount geometry is optimized with specific angles and surface treatments that reduce total internal reflection effects at material interfaces.
Solution Approach 2:
The patent replaces traditional metal mechanical reflector systems with optical solutions based on refractive index management and surface optics. Instead of relying on mechanical reflection surfaces, the design uses material property optimization and geometric configuration to control light paths, eliminating the harmful reflective interfaces.
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 design enhances light emission efficiency by minimizing optical losses and corrosion, providing improved luminous intensity and reliability for applications like automotive and aerospace lighting, while also reducing the forward voltage and increasing the durability of the LED package.
Implementation Method 1
Light extraction and external quantum efficiency of an LED can be limited by a number of factors, including internal reflection. According to the well-understood implications of Snell's law, photons reaching the surface (interface) between an LED surface and the surrounding environment are either refracted or internally reflected.
Implementation Method 2
The reflective cup 14 may be filled with an encapsulant material 20, which may contain a wavelength conversion material such as a phosphor. At least some light emitted by the LED chip 12 at a first wavelength may be absorbed by the phosphor, which may responsively emit light at a second wavelength.
Implementation Method 3
The metal reflector 30 is mounted on the submount 28 and surrounds the LED chips 26 to reflect light emitted by the LED chips 26 away from the LED package 24.
Data Source
AI summary
Solid state light emitting devices including light-emitting diodes (LEDs), and more particularly packaged LEDs are disclosed. In some embodiments, an LED package includes electrical connections that are configured to reduce corrosion of metals within the LED package; or decrease the overall forward voltage of the LED package; or provide an electrical path for serially-connected electrostatic discharge (ESD) chips. In some embodiments, an LED package includes at least two LED chips and a material between the two LED chips that promotes homogeneity of composite emissions from the two LED chips. In this manner, LED packages according to the present disclosure may be beneficial for various applications, including those where a high luminous intensity is desired in a variety of environmental conditions. Such applications include automotive lighting, aerospace lighting, and general illumination.