LED Chip Eutectic Layer Passivation for Oxidation Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting diode (LED) chips experience oxidation of the eutectic material layer due to low melting point, leading to reduced electrical properties and bonding strength when using metal eutectic bonding methods.
Innovation Solution
A surface passivation layer with a metal material having an oxidation potential between -0.2 and -1.8 volts, such as gold or platinum, is applied to cover the eutectic layer, preventing oxidation and enhancing bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a eutectic material layer with low melting point is used to electrically connect LED electrodes, then bonding temperature can be reduced, but oxidation occurs after contact with air which affects electrical property and bonding strength
Solution Approach 1:
A surface passivation layer is introduced as an intermediary between the eutectic material layer and the external environment. This passivation layer prevents direct contact between oxygen and the eutectic material, thereby eliminating oxidation while maintaining the low melting point bonding advantage. The passivation layer acts as a protective mediator that preserves both the low-temperature bonding capability and the electrical/bonding strength reliability.
Solution Approach 2:
The surface passivation layer creates an inert protective environment around the eutectic material layer. By forming this protective barrier, the eutectic material is effectively isolated from oxygen in the ambient atmosphere, preventing oxidation reactions. This approach maintains the low melting point characteristic while ensuring long-term reliability of electrical properties and bonding strength.
2Strength
If a eutectic material layer is used for bonding, then bonding strength can be achieved, but oxidation reduces the bonding strength over time
Solution Approach 1:
The surface passivation layer serves as a protective intermediary that preserves the bonding strength of the eutectic material layer. By preventing oxidation, the passivation layer ensures that the bonding strength remains stable over time and under various environmental conditions, thereby improving the reliability of the bonding interface.
Solution Approach 2:
The surface passivation layer is applied in advance to the eutectic material layer before the bonding process or exposure to ambient environment. This preliminary protective action prevents oxidation from occurring, thereby preserving the bonding strength integrity throughout the product lifecycle.
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 surface passivation layer effectively prevents oxidation of the eutectic layer, maintaining superior electrical properties and bonding ability in LED chips, thereby improving their reliability and performance.
Implementation Method 1
the surface passivation layer covers the second surface of the eutectic layer... the eutectic layer is not easy to contact with air, the eutectic layer can prevent occurrence of an oxidation phenomenon
Data Source
AI summary
A light emitting chip includes a light emitting unit, a eutectic layer and a surface passivation layer. The eutectic layer has a first surface and a second surface opposite to each other. The light emitting chip connects to the first surface of the eutectic layer. The surface passivation layer covers the second surface of the eutectic layer. A material of the surface passivation layer includes at least a metal of an oxidation potential from −0.2 volts to −1.8 volts.