LED Electrode Sulfurization Resistance via Composite Layering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emission devices using Au or AgPt electrodes face issues with durability and corrosion resistance, especially in environments with vibration and sulfur-containing gases, leading to reliability concerns.
Innovation Solution
The use of a conductive material with higher hardness and sulfurization resistance than Au and Ag, such as AgPd, for the electrodes, which are formed in a multi-layer structure with a low-resistance first layer and a high-hardness, high-corrosion-resistant second layer, to secure conduction and prevent damage from vibration and sulfurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are made of Au with low hardness, then corrosion resistance is improved, but strength and resistance to rubbing damage deteriorates
Solution Approach 1:
The patent applies composite materials by forming a multi-layer electrode structure where a soft, corrosion-resistant layer (Au or AgPt) is combined with a hard, wear-resistant layer (diamond-like carbon or similar material). This composite structure simultaneously provides both corrosion resistance from the Au/AgPt layer and resistance to rubbing damage from the hard coating layer, resolving the contradiction between these two properties.
2Quantity of substance
If electrodes are made of AgPt, then cost is reduced compared to Au, but sulfurization resistance deteriorates
Solution Approach 1:
The patent uses composite materials where AgPt serves as the base layer providing cost-effectiveness and inherent sulfurization resistance, while adding a protective hard coating layer that further enhances sulfurization resistance and mechanical durability. This combination allows the electrode to maintain lower cost compared to pure Au while achieving superior sulfurization resistance through the multi-layer structure.
3Ease of manufacture
If electrodes are formed by printing, then ease of manufacture is improved, but resistance to rubbing damage deteriorates due to sparse structure
Solution Approach 1:
The patent applies preliminary action by forming the electrode pattern through printing first, then subsequently applying a hard protective coating layer over the printed electrode. This sequence allows the easy manufacturing advantage of printing to be retained while the later-added hard coating provides the necessary resistance to rubbing damage, compensating for the sparse structure inherent in printed electrodes.
4Reliability
If Au is used for thick electrodes, then corrosion resistance is improved, but cost increases
Solution Approach 1:
The patent applies local quality by using Au or AgPt only in specific locations where corrosion resistance is critical (such as the electrode pattern areas that contact connectors), while using cheaper materials for the protective coating layers and non-critical areas. This localized use of expensive materials maintains corrosion resistance where needed while significantly reducing overall cost compared to using thick Au throughout.
Data Source
AI summary
A light emission device includes: an insulating substrate; a light emitting section including a plurality of LED chips mounted on the insulating substrate; and land electrodes for supplying power to the LED chips. At least a surface of each of the land electrodes is made of a conductive material which is harder than Au and Ag and which has sulfurization resistance to such an extent that secures conduction of each land electrode when a current in a working current range is applied on the land electrode.