LED Chip Reflective Metal Layer Electro-Migration Mitigation
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Solution Overview
Problem
Conventional reflective metal layers in LED chips, such as those made of aluminum or silver, are prone to electro-migration under high-current operation, leading to reduced light efficiency and reliability.
Innovation Solution
A reflective metal layer comprising a combination of aluminum or silver with copper, silicon, tin, platinum, or gold, where the weight percentage of the secondary composition is between 0% and 20%, which reduces grain size and mitigates electro-migration, enhancing reflectivity and overdrive performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If aluminum or silver is used as the reflective metal layer, then the reflectivity and light efficiency are improved, but electro-migration occurs under high-current operation leading to reduced reliability
Solution Approach 1:
The patent applies composite materials by creating an alloy reflective metal layer combining aluminum or silver with small amounts of copper, silicon, tin, platinum, or gold. This composite structure maintains the high reflectivity of aluminum/silver while the added elements mitigate electro-migration, resolving the contradiction between light efficiency and reliability under high-current operation
Solution Approach 2:
The patent changes the compositional parameters of the reflective metal layer by controlling the weight percentage of secondary elements (copper, silicon, tin, platinum, or gold) to be between 0.1-20%. This parameter optimization allows the layer to maintain excellent reflectivity while achieving sufficient electro-migration resistance for improved reliability
2Reliability
If the reflective metal layer composition is modified to reduce electro-migration, then the reliability is improved, but the reflectivity may be reduced
Solution Approach 1:
The patent optimizes the concentration parameters of alloying elements, specifying that copper, silicon, tin, platinum, or gold should constitute 0.1-20% by weight. This precise parameter control ensures that electro-migration resistance is improved while the reflectivity remains high, as the primary aluminum or silver content (80-99.9%) is preserved
3Reliability
If alloying elements are added to the reflective metal layer, then the grain size is reduced and electro-migration is mitigated, but the manufacturing complexity increases
Solution Approach 1:
The patent employs composite materials with a straightforward formulation approach, combining aluminum or silver with limited selections of common alloying elements (copper, silicon, tin, platinum, or gold). The simple compositional specification (0.1-20% by weight) and standard deposition techniques keep manufacturing complexity manageable while achieving superior overdrive performance through grain size reduction and electro-migration mitigation
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 increases reflectivity, improves light efficiency, and reduces electro-migration, thereby maintaining the reliability of the LED chip during long-term operation by stabilizing the operating voltage.
Implementation Method 1
The electrode layer may include a reflective metal layer, which reflects light emitted from the LED to the outside environment
Implementation Method 2
the grain size of the reflective metal layer can be reduced by adding a few second compositions therein, thereby increasing the reflectivity
Implementation Method 3
Aluminum or silver, however, are prone to deterioration due to occurrence of electro-migration under high-current operation
Data Source
AI summary
A light-emitting diode (LED) chip is disclosed. The chip includes a light-emitting diode and an electrode layer on the light-emitting diode. The electrode layer includes a reflective metal layer. The reflective metal layer includes a first composition and a second composition. The first composition includes aluminum or silver, and the second composition includes copper, silicon, tin, platinum, gold or a combination thereof. The weight percentage of the second composition is greater than 0% and less than 20%.