Light-Emitting Device Wire Palladium Diffusion Barrier
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Solution Overview
Problem
Existing light-emitting devices with copper core wires coated with silver experience a decrease in light extraction efficiency over time due to thermal diffusion of copper into the silver layer.
Innovation Solution
A light-emitting device with a wire structure comprising a copper core material, a palladium intermediate layer, and a silver surface layer, where the intermediate layer is arranged between the core and surface layers, preventing thermal diffusion and maintaining light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If copper is used as the wire core material and silver is used as the surface layer to increase light extraction efficiency, then light extraction efficiency is improved, but copper thermal-diffuses into the silver over time causing efficiency to decrease
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the copper core material and the silver surface layer. This barrier layer prevents thermal diffusion of copper atoms into the silver layer while allowing the wire to maintain its electrical and optical functions, thereby resolving the contradiction between initial high light extraction efficiency and long-term stability.
Solution Approach 2:
The wire is designed as a composite structure with multiple layers: copper core material, diffusion barrier layer, and silver surface layer. This composite material approach combines the advantages of each material (copper's conductivity, silver's reflectance) while mitigating their disadvantages (copper's thermal diffusion) through proper material selection and layering.
2Reliability
If a diffusion barrier layer is added between copper core and silver surface layer, then long-term stability is improved, but wire structure complexity increases
Solution Approach 1:
The wire is segmented into distinct functional layers: copper core material for electrical conductivity, diffusion barrier layer for preventing thermal diffusion, and silver surface layer for light extraction. This segmentation allows each layer to perform its specific function optimally while maintaining overall wire performance.
Solution Approach 2:
The invention changes the structural parameters of the wire from a simple two-layer structure to a three-layer structure by introducing the diffusion barrier layer. This parameter change (adding a layer) resolves the stability issue while the thickness and material composition of each layer are optimized to minimize the impact on 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
The device maintains high light extraction efficiency over an extended period, as the palladium intermediate layer prevents copper thermal diffusion into the silver surface layer, ensuring stable performance.
Implementation Method 1
the copper in the core material tends to thermal-diffuse into the silver in the surface layer
Data Source
AI summary
A light-emitting device includes a light emitting element having a pad electrode, and a metal member connected to the pad electrode via a wire. The wire has a layered structure including at least a core material containing copper as a main component, an intermediate layer containing palladium as a main component, and a surface layer containing silver as a main component. The intermediate layer is arranged between the core material and the surface layer.