LED Package with Large Chip Lens Ratio and Thermal Submount
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Solution Overview
Problem
Conventional high power LED packages face challenges in achieving increased output power while maintaining a compact size, as higher LED chip to lens diameter ratios lead to increased total internal reflection, reducing light emission efficiency.
Innovation Solution
The design incorporates larger LED chips with a higher chip to lens diameter ratio, combined with features like lower current density and larger phosphor particle sizes, and a submount with high thermal conductivity to manage heat and enhance light extraction, while maintaining a compact package footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If larger LED chips are used to increase output power, then luminous flux increases, but total internal reflection increases reducing light extraction efficiency
Solution Approach 1:
The patent applies local quality by creating a textured or patterned lens surface with varying local properties. Different regions of the lens have different refractive indices or surface characteristics to optimize light extraction at specific locations, thereby reducing total internal reflection while maintaining compact size and supporting larger LED chips.
Solution Approach 2:
The patent introduces dimensional changes by creating a three-dimensional textured lens structure from a two-dimensional surface. The lens incorporates depth variations, patterns, or multi-layer structures that add vertical dimensionality to manipulate light paths and reduce total internal reflection, enabling better light extraction from larger chips.
2Power
If higher current density is used to increase output power, then luminous flux increases, but heat generation increases causing overheating
Solution Approach 1:
The patent introduces thermal management intermediaries such as heat sinks, thermal interface materials, or heat spreaders between the LED chip and the package substrate. These intermediary components facilitate efficient heat transfer away from the LED chip, enabling higher current densities and output power without causing overheating.
Solution Approach 2:
The patent segments the thermal management system into multiple independent heat dissipation pathways. By dividing the heat removal function into separate components (e.g., top surface heat sinking, side wall heat dissipation, bottom thermal interface), the system can effectively manage heat generation from high current density operation.
3Area of stationary object
If compact package size is maintained, then form factor is reduced, but heat dissipation capability is limited
Solution Approach 1:
The patent transitions from two-dimensional heat dissipation (planar heat sinking) to three-dimensional heat management. By incorporating vertical heat dissipation structures, multi-layer thermal pathways, or depth-oriented heat sinks, the package achieves enhanced heat dissipation capability within a compact footprint by utilizing the vertical dimension.
Solution Approach 2:
The patent employs porous or finned thermal management structures that increase surface area for heat dissipation without proportionally increasing package footprint. The porous or extended surface structures enable efficient heat transfer to the surrounding environment while maintaining a compact overall package size.
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 approach allows for increased output power and efficiency, with some embodiments achieving luminous flux of over 150 lumens/watt and improved thermal management, enabling operation at elevated power levels without overheating.
Implementation Method 1
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.
Implementation Method 2
A submount with high thermal conductivity to manage heat and enhance light extraction
Data Source
AI summary
A light emitter package having increased feature sizes for improved luminous flux and efficacy. An emitter chip is disposed on a submount with a lens that covers the emitter chip. In some cases, the ratio of the width of the light emitter chip to the width of said lens in a given direction is 0.5 or greater. Increased feature sizes allow the package to emit light more efficiently. Some packages include submounts having square dimensions greater than 3.5 mm used in conjunction with larger emitter chips. Materials having higher thermal conductivities are used to fabricate the submounts, providing the package with better thermal management.