Surface Activated Bonding for Light Emitting Device
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Solution Overview
Problem
Conventional light emitting devices with a sapphire growth substrate and GaN nucleation layer exhibit weak bonding strength, leading to potential detachment during use.
Innovation Solution
A light emitting device with a sapphire substrate and a wavelength converting member made of aluminum oxide, featuring regions with irregular atomic arrangements for direct bonding, utilizing a surface activated bonding technique to enhance bonding strength without the need for adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermal compression bonding is used to bond the sapphire growth substrate and GaN nucleation layer, then the bonding process is simple, but the bonding strength is weak leading to detachment during use
Solution Approach 1:
The invention changes the bonding parameters from simple thermal compression to a more complex process involving surface activation, temperature control (50-200°C), and pressure application. This parameter change transforms the bonding mechanism to achieve much stronger bonding strength while maintaining reasonable manufacturing complexity
Solution Approach 2:
The invention replaces the purely mechanical thermal compression bonding with a chemical-physical bonding mechanism involving surface activation. The surface activation creates reactive groups on the bonding surfaces, enabling chemical bonding in addition to mechanical bonding, thereby significantly enhancing the overall bonding strength
2Strength
If adhesive materials are used to bond the light emitting element and wavelength converting member, then the bonding strength can be improved, but the device complexity and potential optical loss increase
Solution Approach 1:
The invention extracts and eliminates the adhesive material from the bonding structure. By directly bonding the light emitting element to the wavelength converting member through surface activation, the patent removes the intermediate adhesive layer, thereby reducing device complexity while maintaining strong bonding strength
Solution Approach 2:
The invention merges the light emitting element and wavelength converting member into a single bonded structure without intermediate materials. The direct bonding through surface activation combines these two components into an integrated assembly, reducing structural complexity and eliminating potential failure interfaces
3Strength
If adhesive materials are used for bonding, then bonding strength can be enhanced, but optical loss and reduced light extraction efficiency occur
Solution Approach 1:
The invention extracts and removes the adhesive material that causes optical loss. By achieving direct bonding between the light emitting element and wavelength converting member, the adhesive layer is eliminated, thereby removing the source of optical absorption and scattering that would reduce light extraction efficiency
Solution Approach 2:
The invention addresses optical properties by creating a bonding interface that is transparent to the relevant wavelengths. The direct bonding without adhesive materials ensures that the optical path remains clear, maintaining high light extraction efficiency and preventing energy loss through the bonding interface
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 solution provides a light emitting device with significantly improved bonding strength between the light emitting element and the wavelength converting member, reducing strain, stress, and optical loss, while enhancing light extraction efficiency and luminous flux.
Implementation Method 1
a step of bonding the light emitting element and the wavelength converting member by using a surface activated bonding technique
Data Source
Figure 1~2
Figure 3A~3C
AI summary
Provided is a light emitting device having strong bonding strength between the light emitting element and the wavelength converting member is provided. In the light emitting device, a light emitting element and a wavelength converting member are bonded. Particularly, the light emitting element has, from the wavelength converting member side, a first region and a second region, the wavelength converting member has, from the light emitting element side, a third region and a fourth region. The first region has an irregular atomic arrangement compared with the second region, the third region has an irregular atomic arrangement compared with the fourth region, and the first region and the third region are directly bonded.