ALD Transparent Coating for LED Ceramic Bonding
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Solution Overview
Problem
The existing methods for manufacturing Light Emitting Devices using polymer glue between a light emitting diode (LED) and a ceramic phosphor plate result in optical inefficiency, thermal conductivity issues, and organic contamination, particularly in Thin-Film side coat LED architectures, due to the glue's low refractive index and poor thermal conductivity.
Innovation Solution
The use of Atomic Layer Deposition (ALD) to apply a transparent material with higher thermal conductivity and matched refractive index to fill the gap between the LED and the ceramic plate, eliminating the need for polymer glue and enhancing thermal conductivity and optical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer glue is used to bond the ceramic plate to the LED, then bonding is achieved, but thermal conductivity is poor and optical efficiency is reduced
Solution Approach 1:
The patent removes the polymer glue layer from the bonding interface between the LED and ceramic plate. By eliminating this intermediate layer with poor thermal and optical properties, the invention achieves direct bonding of the ceramic plate to the LED chip, thereby resolving the contradiction between bonding strength and thermal conductivity.
Solution Approach 2:
The patent introduces a novel bonding mechanism using atomic layer deposition (ALD) to create an inorganic intermediate layer that serves as both adhesive and thermal conduit. This ALD-derived layer acts as a superior mediator compared to polymer glue, providing both strong bonding and excellent thermal conductivity simultaneously.
2Strength
If polymer glue is used for bonding, then attachment is achieved, but optical efficiency is reduced due to low refractive index
Solution Approach 1:
The patent eliminates the polymer glue layer that causes optical inefficiency due to its low refractive index. By removing this optical barrier, light transmission from the LED through the ceramic plate is significantly improved, thereby resolving the contradiction between bonding strength and optical efficiency.
Solution Approach 2:
The patent changes the refractive index parameter of the bonding interface by replacing polymer glue (low refractive index) with an inorganic material deposited via ALD that has a refractive index matched to the surrounding materials. This parameter change optimizes optical coupling and light extraction efficiency.
3Strength
If polymer glue is used for bonding, then attachment is achieved, but organic contamination increases
Solution Approach 1:
The patent removes the organic polymer glue material from the device structure, thereby eliminating the source of organic contamination. This extraction resolves the contradiction between achieving bonding strength and minimizing harmful organic contaminants in the final device.
Solution Approach 2:
The patent replaces the disposable polymer glue with a permanent inorganic bonding layer deposited via ALD. This inorganic layer provides lasting bonding without the degradation and contamination issues associated with organic materials over time.
4Reliability
If ALD is used to deposit transparent material, then thermal conductivity improves, but manufacturing complexity increases
Solution Approach 1:
The patent employs atomic layer deposition (ALD) technology that can simultaneously achieve multiple functions: creating the bonding layer, providing thermal conduction pathway, and forming the optical interface. This multi-functionality resolves the contradiction between improved thermal conductivity and manufacturing complexity, as the same process delivers multiple benefits.
Solution Approach 2:
The patent replaces traditional mechanical bonding methods (using polymer adhesives applied and cured mechanically) with a vapor-phase deposition process (ALD). This substitution eliminates the need for separate bonding and thermal management steps, integrating multiple functions into a single manufacturing process.
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 increases the reliability and efficiency of Light Emitting Devices by improving thermal conductivity and reducing organic contamination, leading to enhanced optical output and color uniformity.
Implementation Method 1
Atomic Layer Deposition (ALD) is a process in which a thin film deposition method in which a film is grown on a substrate by exposing its surface to alternate precursor gases
Implementation Method 2
increase the efficiency of the optical output of the Light Emitting Device... improve the thermal conductivity between the ceramic plate and the LED
Implementation Method 3
providing optical coupling of blue light into the Lumiramic plate to form white light
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A method of manufacturing of a Light Emitting Device that has increased reliability and efficiency. Specifically, the disclosed methods uses Atomic Layer Deposition to improve the thermal conductivity between the ceramic plate and the LED, decrease the amount of organic contamination, and increase the efficiency of the optical output of the Light Emitting Device.