LED Lighting Unit With Thermally Stable Microstructured Layer
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Solution Overview
Problem
Compact LED lighting units face challenges in miniaturization due to the limitations of Fresnel lens designs, which require a specific distance from the LED and are prone to damage during reflow soldering, limiting the package height and optical output while exposing optical components to high temperatures.
Innovation Solution
A microstructured layer made of thermally stable and optically transparent materials, such as silicone or silicate, is used to support the LED-based light emitting structure, allowing for a reduced height while maintaining optical collimation and withstanding high temperatures during soldering, enabling a more compact and efficient LED lighting unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a Fresnel lens is used to collimate light from the LED, then the beam profile is improved, but the package height increases and the optical components are exposed to high temperatures during reflow soldering
Solution Approach 1:
The patent changes the material parameter from conventional lens materials to thermally stable materials (silicone, silicate, glass, or ceramic) that can withstand reflow soldering temperatures. This parameter change allows the optical component to maintain its collimation function while surviving the high-temperature soldering process, eliminating the need for separate lens housings and reducing overall package height
Solution Approach 2:
The patent employs composite material structures where the microstructured optical layer is integrated with thermally stable substrate materials. This composite approach combines the optical collimation properties with thermal resistance, creating a single integrated component that performs both functions while maintaining compact dimensions suitable for thin device integration
2Length of stationary object
If the package height is reduced to make devices thinner, then the compactness is improved, but the optical output is limited due to the minimum distance required for Fresnel lens operation
Solution Approach 1:
The patent fundamentally changes the optical design parameter by replacing the Fresnel lens with a microstructured layer positioned at a reduced distance from the LED. This parameter change in both optical architecture and component positioning enables compact package heights while maintaining adequate optical output through the unique light-modifying properties of the microstructured thermally stable layer
3Ease of manufacture
If conventional lens materials are used, then the manufacturing is easier, but the optical components are damaged during reflow soldering due to high temperatures
Solution Approach 1:
The patent integrates optical functionality into thermally stable materials (silicone, silicate, glass, or ceramic) that inherently withstand reflow soldering temperatures. This material integration eliminates the reliability issue of thermal damage while maintaining manufacturability through established processes for forming microstructured layers in these thermally resistant materials
Solution Approach 2:
The patent changes the material composition parameter from conventional temperature-sensitive lens materials to thermally stable materials. This parameter change enables the optical component to survive high-temperature soldering processes, achieving both ease of manufacture through standard semiconductor packaging processes and high reliability under thermal stress
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 solution allows for a smaller and more efficient LED lighting unit with increased optical output, as the microstructured layer maintains dimensional stability and optical functionality, even under high temperatures, enabling integration into thinner devices without compromising performance.
Implementation Method 1
One example of Fresnel lens comprises optical elements in the form of facets that refract light in the center of the lens
Implementation Method 2
reflect light upwards at the periphery of the lens in order to collimate the light emitted by the LED
Implementation Method 3
These packages typically use a high power blue LED covered with a phosphor layer which converts a part of the radiation into the green-red spectral range to result in a white color point
Data Source
AI summary
An LED lighting unit comprising a support structure (14), an LED-based light emitting structure (10) mounted within the support structure and an optical beam shaping arrangement (50, 52) over the top of the support structure. The optical beam shaping arrangement comprises an optically transparent and thermally stable material, and the support structure supports the microstructured layer at a small height above the LED-based light emitting structure. This height may for example be less than 0.5 mm. The optical beam shaping arrangement enables a compact and low height lighting unit to be mounted on a carrier by reflow soldering without damaging the optical beam-shaping component.