Aircraft LED Light Unit Thermal Management via Segmented PCB
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Solution Overview
Problem
High power LEDs in aircraft lighting systems face thermal management challenges due to limited thermal transfer, leading to increased LED junction temperatures and reduced performance, especially when closely packed in arrays without electrically isolated thermal pads.
Innovation Solution
Incorporating a printed circuit board with a metal core layer and dielectric layer, where one anode or cathode of the LED is connected to an electrical conductor on the dielectric layer and the other to the metal core layer, enhancing thermal transfer and reducing junction temperatures through improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple LEDs are arranged closely in an array on a PCB without electrically isolated thermal pads, then the device complexity and manufacturing are simplified, but the thermal transfer from LED junctions is limited causing increased junction temperatures and reduced LED performance
Solution Approach 1:
The PCB is segmented into multiple electrically isolated thermal pads (first thermal pad, second thermal pad, etc.) that are electrically insulated from each other through dielectric layers. This segmentation allows each LED to have its own dedicated thermal pathway to a specific thermal pad, enabling independent thermal management for each LED while maintaining electrical isolation. The thermal pads are further segmented and connected to heat sinks through thermally conductive materials, creating a hierarchical thermal management structure.
Solution Approach 2:
Dielectric layers are introduced as intermediary elements between adjacent thermal pads to provide electrical isolation while allowing thermal transfer. These dielectric layers act as mediators that prevent electrical short circuits between adjacent LEDs and their thermal pads, yet still permit thermal energy to dissipate from the LED junctions through the thermal pads to the heat sinks. The dielectric layers enable the system to simultaneously achieve electrical isolation and thermal management.
2Illumination intensity
If high power LEDs are used to increase light emission, then the illumination intensity is improved, but the thermal load and junction temperatures increase leading to reduced LED lifetime and performance
Solution Approach 1:
The invention changes the thermal management parameters by introducing multiple electrically isolated thermal pads with dedicated thermal pathways to heat sinks. This parameter change in the thermal management architecture enables high power LEDs to operate at higher currents for increased light emission while maintaining acceptable junction temperatures through improved heat dissipation. The thermal resistance parameters are reduced by creating multiple parallel thermal pathways from each LED junction through its dedicated thermal pad to the heat sink.
3Temperature
If thermal pads are added to improve heat dissipation, then the thermal transfer is enhanced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The thermal pads serve multiple functions simultaneously: they provide thermal pathways for heat dissipation, act as electrical connection points for LEDs, and function as mounting surfaces for attaching heat sinks. The dielectric layers between thermal pads provide both electrical isolation and structural support. This multi-functionality reduces the need for separate components and simplifies the overall manufacturing process despite the enhanced thermal management capabilities.
Solution Approach 2:
The thermal management structure employs a nested architecture where thermal pads are embedded within the PCB layers, dielectric layers are nested between adjacent thermal pads, and heat sinks are nested onto the thermal pads through thermally conductive materials. This nested structure allows multiple functional elements to be integrated within a compact PCB footprint, enabling enhanced thermal management without proportionally increasing the overall device size or manufacturing complexity.
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 configuration results in higher LED performance and efficiency by maintaining lower junction temperatures, allowing for increased light emission and reduced thermal overload, even at higher operating currents.
Implementation Method 1
the metal core layer is coupled to a second terminal of the power source. Thus, there is increased thermal transfer of heat resulting from power dissipation from the LED junction to the metal core layer through one of the anode and cathode of the respective LED
Implementation Method 2
the dielectric layer electrically isolates the electrical conductor from the metal core layer
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
An aircraft LED light unit (1, 10) comprises at least one printed circuit board (2, 2-1-2-4) which comprises at least one metal core layer (21) and at least one dielectric layer (22), and at least one LED (3, 3-1-3-3, 3-111-3-43n) disposed on the printed circuit board and which comprises an anode (31) and a cathode (32) for electrically coupling to a power source (12). One of the anode and cathode (31, 32) of the at least one LED is connected to an electrical conductor (4) which is disposed on the dielectric layer (22) and is coupled to a first terminal of the power source (12), wherein the dielectric layer (22) electrically isolates the electrical conductor (4) from the metal core layer (21), and the other one of the anode and cathode (31, 32) of the at least one LED is connected to the metal core layer (21) of the at least one printed circuit board, wherein the metal core layer (21) is coupled to a second terminal of the power source (12).