UV Bonding Wire Composition for Reflectance and Electromigration Resistance
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Solution Overview
Problem
Light emitting devices for ultraviolet light emission face challenges in achieving high light extraction efficiency due to the absorption of ultraviolet light by bonding wires, and they also suffer from electromigration issues that lead to breakage failures.
Innovation Solution
The use of a bonding wire made from materials such as alloys containing Al and Cu, Mg and Cu, or Mg, or a wire structure with a Cu layer and an Al or Mg layer, which enhances reflectance and reduces electromigration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Al is used as a bonding wire to achieve high reflectance and light extraction efficiency, then light extraction efficiency is improved, but electromigration resistance deteriorates leading to breakage failures
Solution Approach 1:
The bonding wire is constructed as a composite structure with a core material (Al or Al alloy) providing high reflectance for UV light extraction, and a coating material (Mg, Mg alloy, or Cu) applied on the surface to provide electromigration resistance. This composite structure combines the advantages of both materials to resolve the contradiction between light extraction efficiency and reliability.
2Illumination intensity
If Al is used as a bonding wire, then high reflectance is obtained, but the bonding wire suffers breakage failure due to electromigration
Solution Approach 1:
The bonding wire combines Al or Al alloy core material with high reflectance properties and Mg, Mg alloy, or Cu coating material with high electromigration resistance and stability. This composite structure maintains high reflectance for UV light extraction while the coating layer prevents electromigration-induced degradation, extending the bonding wire's operational life span.
Solution Approach 2:
By changing the material composition parameters of the bonding wire from pure Al to Al-based or Al-Mg/Cu composite materials, the patent optimizes both optical properties (reflectance) and electrical stability (electromigration resistance), thereby extending the operational life span while maintaining high reflectance.
3Productivity
If a bonding wire material with high reflectance is used to improve light extraction efficiency, then light extraction efficiency is improved, but electromigration causes breakage failures
Solution Approach 1:
The bonding wire employs a composite material structure where the core (Al or Al alloy) provides high reflectance to improve UV light extraction efficiency, while the coating layer (Mg, Mg alloy, or Cu) provides high electromigration resistance to ensure reliability. This composite approach simultaneously achieves both improved productivity and reliability.
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 the light extraction efficiency of ultraviolet light while significantly reducing electromigration-induced failures, thereby extending the lifespan and enhancing the reliability of the light emitting device.
Implementation Method 1
Al, which has a high reflectance, for the bonding wire from the viewpoint of light extraction efficiency
Implementation Method 2
since Al is prone to electromigration, when Al is used as a bonding wire, there is a possibility that the bonding wire may suffer a breakage failure due to electromigration
Data Source
AI summary
A light emitting device includes: a light emitting element containing a group III nitride and configured to emit ultraviolet light; and a bonding wire electrically connected to the light emitting element, and the bonding wire contains at least one selected from the group consisting of: an alloy containing Al as a main component and containing Cu; an alloy containing Mg as a main component and containing Cu; Mg; and an alloy containing Mg, or includes a first layer containing Cu or an alloy containing Cu, and a second layer containing one selected from the group consisting of: Al; an alloy containing Al; Mg; and an alloy containing Mg.