Close-Packed LED Arrays with Thermal Vias
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Solution Overview
Problem
Conventional light-emitting diode (LED) arrays face challenges such as reduced luminance due to spaced LEDs, overheating, and poor thermal dissipation, particularly in close-packed configurations and vertical LED arrays with dielectric layers.
Innovation Solution
A light-emitting system with close-packed LEDs and electrically isolated substrates, where LEDs are configured with vias for thermal and electrical connection to a heat dissipation substrate, allowing operation at high current densities and reducing current crowding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LEDs are spaced far apart to avoid absorption of sidewall light emission, then light emission quality is improved, but luminance and area utilization deteriorate
Solution Approach 1:
The patent transitions from lateral LED emission to vertical LED emission, changing the dimension of light output. Vertical LEDs emit light upward through the top surface rather than sideways, allowing close-packed arrangements without light absorption issues while maintaining high area utilization and luminance.
Solution Approach 2:
The patent merges multiple LEDs into a close-packed array configuration where LEDs are positioned adjacent to each other with minimal spacing. This merging approach maximizes area utilization and luminance while the vertical orientation prevents light absorption problems that would normally require spacing.
2Illumination intensity
If LEDs are operated at high current densities to increase luminance, then light output is improved, but overheating and burnout worsen
Solution Approach 1:
The patent introduces a heat dissipation substrate as an intermediary between the LEDs and the mounting surface. This substrate provides enhanced thermal management, allowing LEDs to operate at high current densities for increased luminance while preventing overheating through efficient heat sinking.
Solution Approach 2:
The patent extracts the thermal management function by separating it from the standard mounting process. A dedicated heat dissipation substrate is used to remove heat from the LED array, enabling high current density operation without burnout while maintaining high luminance output.
3Reliability
If a dielectric layer is present between LEDs and substrate for electrical isolation, then electrical isolation is improved, but thermal dissipation worsens
Solution Approach 1:
The patent segments the functional layers by separating the electrical isolation function from the thermal management function. Electrical isolation is achieved through PCB trace routing and ground planes rather than a continuous dielectric layer, allowing direct thermal contact between LEDs and the heat dissipation substrate for improved thermal dissipation while maintaining electrical isolation.
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 system achieves high luminance and efficient heat dissipation, enabling LEDs to be operated at higher current densities without overheating, thereby enhancing performance and longevity.
Implementation Method 1
efficient heat dissipation
Implementation Method 2
light-emitting diodes (LEDs)
Data Source
AI summary
Aspects of the present disclosure relate to a light-emitting system comprising a plurality of LEDs having relatively small nearest-neighbor distances (e.g., a close-packed array of LEDs). In some cases, one or more LEDs of the plurality of LEDs comprise a via between a semiconductor layer (e.g., an n-type semiconductor layer forming part of a p-n junction) and a heat dissipation substrate. The presence of the vias may advantageously reduce or eliminate current crowding and may allow the LEDs to be operated at a high current density (e.g., at least 1A/mm2). In some cases, one or more LEDs of the plurality of LEDs comprise a first contact pad (e.g., an n-side contact pad) and a second contact pad (e.g., a p-side contact pad) positioned in any location, which may allow the LEDs to be configured in series or in parallel, or to be individually addressable. The first and second contact pads of the LEDs may be electrically connected to other elements of the light-emitting system (e.g., other LEDs, an anode, a cathode, a busbar) via one or more wire bonds, and at least a portion of the one or more wire bonds may be positioned outside light emission areas of the LEDs. Additionally, the light-emitting system may further comprise one or more anodes and one or more cathodes positioned in any location. In some cases, one or more LEDs of the plurality of LEDs are mounted on a substrate (e.g., a printed circuit board, a lead frame substrate, a composite substrate) that is electrically isolated from any anodes or cathodes of the light-emitting system.