LED Package T-Shaped Electrodes Oxidation Resistance
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Solution Overview
Problem
Traditional LED packages face challenges with oxidation resistance due to weak bonding between the encapsulation layer and substrate, allowing humid air to penetrate and cause electrode oxidation, and poor heat dissipation, which accelerates degradation.
Innovation Solution
The LED package features a high heat conductive substrate with T-shaped electrodes and oxidation-resistant metal coating layers in grooves, along with a reflective cup and encapsulation layer to enhance oxidation resistance and heat dissipation by increasing contact areas and using Au for the metal coating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an encapsulation layer is formed on the substrate to encapsulate the LED die, then the LED die is isolated from humid ambient air, but humid air easily permeates into the inside of the LED package from the substrate-encapsulation layer interface due to weak bonding force, causing electrode oxidation
Solution Approach 1:
The patent applies preliminary action by forming oxidation-resistant metal coating layers (such as Au, Ag, or Ni) on the first and second electrodes before encapsulation. This pre-protection ensures that even if humid air permeates through the encapsulation layer interface, the electrodes are already protected from oxidation, thus resolving the contradiction between encapsulation effectiveness and interface bonding weakness.
Solution Approach 2:
The patent creates an inert environment by using oxidation-resistant metal coating layers on the electrodes. These coating layers act as a barrier that prevents oxygen and moisture from reacting with the electrode materials, effectively creating a locally inert atmosphere around the electrodes despite the presence of humid air in the package interior.
2Reliability
If the encapsulation layer is made of silicon resin or epoxy resin, then the LED die is encapsulated, but the bonding force between the encapsulation layer and substrate is weak, allowing humid air to penetrate easily
Solution Approach 1:
The patent employs composite materials by combining the encapsulation layer (silicon resin or epoxy resin) with oxidation-resistant metal coating layers on the electrodes. This composite structure addresses the weak bonding issue by providing an additional protection mechanism (metal coating) that compensates for the insufficient bonding strength at the encapsulation-substrate interface.
Solution Approach 2:
The oxidation-resistant metal coating layers are formed on the electrodes before the encapsulation process. This preliminary protective action ensures that even if the encapsulation layer develops weak bonding or allows humid air penetration over time, the electrodes remain protected from oxidation throughout the product lifecycle.
3Reliability
If the LED die is mounted on the substrate with electrodes, then electrical connection is achieved, but heat generated by the LED die is difficult to be dissipated, accelerating deterioration and degradation
Solution Approach 1:
The patent introduces a heat dissipation layer as an intermediary between the LED die and the substrate. This intermediate layer serves as a thermal conduit that efficiently transfers heat from the LED die to the substrate, resolving the contradiction between maintaining electrical connection and improving heat dissipation. The heat dissipation layer acts as a mediator that separates the electrical and thermal management functions.
Solution Approach 2:
The patent changes the thermal parameter of the package structure by introducing a heat dissipation layer with high thermal conductivity. This parameter change (increasing thermal conductivity in the heat dissipation path) enables efficient heat removal from the LED die without affecting the electrical connection between the die and electrodes.
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 design significantly improves oxidation resistance and heat dissipation, prolonging the LED package's lifespan by preventing air oxidation and effectively dissipating heat generated by the LED die.
Implementation Method 1
both the first and the second electrodes have T-shaped transverse cross sections along a thickness direction thereof; both the top faces of the first and second electrodes are exposed at the top surface of the substrate
Implementation Method 2
a high heat conductive substrate with T-shaped electrodes and oxidation-resistant metal coating layers in grooves
Data Source
AI summary
A light emitting diode (LED) package includes a substrate, a first electrode, a second electrode, an LED die mounted on the substrate and electrically connected to the first and the second electrodes, and an encapsulation layer encapsulating the LED die. Both the first and the second electrodes are embedded in the substrate and spaced from each other. Each of the first and the second electrodes includes a top face and a bottom face, with the top face and the bottom face thereof being exposed at a top surface and a bottom surface of the substrate, respectively. The top face of the first electrode defines a first groove therein. An oxidation-resistant metal coating layer is filled in the first groove. A positive bonding pad of the LED die directly contacts with a top face of the first oxidation-resistant metal coating layer.