LED Package Microstructures for Light Extraction

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Solution Overview

Problem

Conventional LED packages with smooth surfaces suffer from reduced efficiency due to total internal reflection, leading to a higher chance of light being reflected back rather than escaping, which decreases the overall light extract efficiency.

Innovation Solution

The implementation of microstructures on the top and side surfaces of LED packages, formed through compression molding or sandblasting processes, reduces total internal reflection by creating rough surfaces that allow more light to escape, thereby enhancing light extract efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If smooth surfaces are used for LED package encapsulating layer, then manufacturing process is simple, but light extract efficiency is reduced due to total internal reflection

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidlight extract efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent changes the surface parameter from smooth to rough by introducing microstructures (protrusions or recesses) on the encapsulating layer. This parameter change reduces total internal reflection and improves light extract efficiency by approximately 5%, while maintaining compatibility with existing manufacturing processes like compression molding and sandblasting.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces curved microstructures (protrusions or recesses) on the encapsulating layer surface. These curved features alter the angle of light incidence and reduce total internal reflection, enabling more light to escape from the LED package while maintaining manufacturing feasibility through processes like sandblasting or molding.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Loss of energy

If microstructures are added to improve light extract efficiency, then light escape is improved, but device complexity increases

Engineering Contradiction:

Improvelight extract efficiencyVSAvoidsurface structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent modifies the surface parameter by adding microstructures, but keeps the modification process simple by using existing manufacturing techniques like compression molding with textured molds or sandblasting. This approach improves light extract efficiency without significantly increasing device complexity or manufacturing difficulty.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The microstructures on the encapsulating layer automatically reduce total internal reflection through their geometric configuration. The structures passively alter light paths without requiring additional active components or complex control mechanisms, thereby improving light extract efficiency while maintaining relatively simple device architecture.

Inventive Principle:

Principle #25Self-service

3Loss of energy

If sandblasting process is used to create rough surfaces, then light extract efficiency is improved, but manufacturing precision control becomes more difficult

Engineering Contradiction:

Improvelight extract efficiencyVSAvoidsurface roughness control

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent applies sandblasting as a preliminary surface treatment step after the encapsulating layer is formed. This preliminary action creates the desired rough surface texture that improves light extract efficiency. By controlling parameters like blasting media size, pressure, and duration, the process achieves consistent surface roughness without requiring ultra-precise control, thereby improving light extraction while maintaining manufacturing feasibility.

Inventive Principle:

Principle #10Preliminary action

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 introduction of microstructures on LED package surfaces increases light extract efficiency by approximately 5% compared to smooth-surfaced packages, improving the overall performance of LED lighting.

Implementation Method 1

The LED light has relatively higher chance to be reflected back from the smooth surfaces due to total internal reflection. It, thereby, decreases the efficiency of the SMT LED package.

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS11217735B2LED package with surface textures and methods of formation

Publication Date: 2022.01.04 LUMINUS INC

AI summary

Methods and apparatus are provided for LED packages with surface textures. In one novel aspect, microstructures are formed on surfaces of the LED package such that light extract efficiency is improved. In one embodiment, the LED package has a silicone-encapsulating layer scattered with phosphors. In another embodiment, the LED package has a leadframe substrate. The microstructure can be micro lens, micro dents, micro pillars, micro cones, or other shapes. The microstructures can be periodically arranged or randomly arranged. In one novel aspect, the compression molding process is used to form rough surfaces. The molding block or the release film is modified with microstructures. In another novel aspect, sandblasting process is used. In one embodiment, microstructures are formed on sidewalls using the sandblasting process. The hardness, the angle, and/or the size of the blasting media are selected to improve the efficiency of the LED package.