Hybrid Flip Chip LED Array Thermal Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LED devices face challenges with thermal efficiency due to the use of sapphire substrates, limited post-manufacturing color tunability, and fragile wire bonds, leading to non-uniform color emission and sensitivity to physical damage and dirt accumulation.
Innovation Solution
The integration of flip chip LEDs and chip scale package LEDs with a phosphor-containing encapsulant, arranged in alternating rows, and a variable current delivery circuit with a resistance device to achieve independent control of power delivery to different LED sets, enhancing thermal conductivity and color uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If phosphor material is placed directly on top of the p-n junction of the LED, then the LED structure is simplified, but thermal efficiency deteriorates because heat conduction through sapphire substrate is poor
Solution Approach 1:
The LED device is divided into multiple independent LED chips mounted on a circuit board, with each chip having its own heat dissipation path through the board rather than relying on sapphire substrate conduction. This segmentation allows each chip to manage its own thermal load independently.
Solution Approach 2:
A metal core circuit board is introduced as an intermediary thermal management component between the LED chips and the environment. The metal core provides superior thermal conduction compared to sapphire, acting as a heat sink and thermal pathway that improves overall thermal efficiency.
2Ease of manufacture
If wire bonds are used to make electrical connections, then electrical connectivity is achieved, but reliability deteriorates due to fragility and sensitivity to physical damage
Solution Approach 1:
The wire bonds are completely removed from the LED chip structure. Instead, electrical connections are made directly through the mounting board using conductive traces and solder bumps on the LED chip electrodes, eliminating the fragile wire bond component entirely.
Solution Approach 2:
The mechanical wire bond connection system is replaced with a solder-based electrical connection system. The LED chips are mounted with their electrodes directly contacting conductive paths on the circuit board, using solder joints instead of mechanical wire bonding.
3Illumination intensity
If phosphor materials are located on the LED chip, then color conversion is achieved, but thermal management deteriorates because heat is conducted to the phosphor materials
Solution Approach 1:
The phosphor materials are moved from a two-dimensional position on the LED chip surface to a three-dimensional location within the encapsulating material surrounding the chip. This spatial relocation separates the phosphor from the heat-generating junction while maintaining optical interaction.
Solution Approach 2:
The encapsulating material serves as an intermediary medium between the LED chip and the phosphor materials. This material allows optical energy transfer for color conversion while providing thermal isolation, preventing direct heat conduction from the junction to the phosphor.
4Quantity of substance
If LED chips are closely spaced in arrays, then luminous flux is increased, but manufacturing complexity increases due to additional processing steps
Solution Approach 1:
Multiple LED chips are mounted in close proximity on a single circuit board and electrically connected through conductive traces on the board. This merging approach allows high luminous flux output while simplifying manufacturing by eliminating the need for individual packaging and complex inter-chip connections.
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 improves thermal efficiency, allows for post-manufacturing color tunability, reduces the risk of physical damage, and enhances color uniformity and light distribution, while eliminating the need for fragile wire bonds and reducing dirt depreciation.
Implementation Method 1
A portion of the light emitted by the LED chip is absorbed by the phosphor material(s) and re-emitted at different wavelengths.
Implementation Method 2
Heat may be conducted through a sapphire substrate to the mounting material of the LED chip
Implementation Method 3
Electrical contact is made using thermosonic bonding or a type of solder attach.
Data Source
AI summary
A LED device is disclosed. The device has a LED area, a boundary element surrounding the LED area, a plurality of chip scale package LEDs in the LED area, a plurality of flip chip LEDs in the LED area, an encapsulate, a first conductive path, and a second conductive. The encapsulate covers the plurality of chip scale package LEDs and the plurality of flip chip LEDs in the LED area. The encapsulate has phosphor. The first conductive path connects the plurality of chip scale package LEDs. The second conductive path connects the plurality of flip chip LEDs. The plurality of chip scale package LEDs and the plurality of flip chip LEDs in the LED area are arranged in rows. Each row comprises alternating chip scale package LEDs and flip chip LEDs.