LED Electrode Passivation Structure Against Moisture Leakage
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Solution Overview
Problem
Conventional light-emitting devices face issues with water vapor permeation through insulative and protective layers, leading to current leakage and electrode damage, especially in harsh environments with high humidity and salt exposure, which affects their reliability and longevity.
Innovation Solution
A light-emitting device design featuring a semiconductor light-emitting stack with a passivation layer and insulating layer that reduces water vapor permeation and built-in electric field effects, using a silicon-rich insulating layer and a passivation layer with small-sized pin-holes to cover the semiconductor stack and electrodes, thereby enhancing hydrophobicity and preventing electrode separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon oxide or silicon nitride is used as the insulative and protective layer, then the device structure is simple and manufacturing is easier, but water vapor permeation occurs leading to electrical failures
Solution Approach 1:
The patent uses a composite protective layer structure combining silicon oxide (or silicon nitride) with organic protective materials such as silicon resin, acrylic resin, or epoxy resin. This composite structure leverages the excellent adhesion and hydrophobicity of organic materials while maintaining the electrical insulation properties of the inorganic layer, thereby preventing water vapor permeation and improving device reliability without significantly complicating the manufacturing process.
Solution Approach 2:
The patent modifies the chemical composition and surface properties of the protective layer by incorporating organic materials with specific hydrophobic characteristics. This parameter change in material composition transforms the surface energy and contact angle properties, creating a water vapor barrier that prevents permeation while maintaining manufacturing feasibility through established coating processes.
2Area of stationary object
If the distance between electrodes is reduced to minimize device size, then the device area is smaller, but the built-in electric field strength increases causing water vapor to form currents
Solution Approach 1:
The composite protective layer structure serves as an effective barrier against water vapor ingress, preventing the formation of conductive paths even in the high electric field environment created by closely spaced electrodes. The hydrophobic organic material component specifically addresses the water vapor issue while the inorganic component maintains electrical insulation.
Solution Approach 2:
The protective layer is applied in advance to prevent water vapor from reaching the electrode region. By establishing this protective barrier before the device operates in harsh environments, the patent preemptively counteracts the harmful effect of water vapor formation and current leakage that would otherwise be exacerbated by the high electric field strength.
3Device complexity
If conventional insulative layers are used, then the device structure is simpler, but pin-holes form allowing water vapor to permeate through
Solution Approach 1:
The patent employs a composite protective layer combining inorganic materials (silicon oxide or silicon nitride) with organic protective materials (silicon resin, acrylic resin, or epoxy resin). This composite structure addresses the pin-hole issue by using the organic material to fill and seal defects in the inorganic layer, creating a continuous barrier against water vapor permeation while maintaining relatively simple device architecture.
Solution Approach 2:
The organic protective material specifically targets and addresses the local缺陷 (pin-holes) in the inorganic insulative layer. By applying the organic material as a coating over the inorganic layer, the patent locally reinforces the protective function at the defect sites without requiring complete restructuring of the entire device, thus maintaining simplicity while improving reliability.
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 effectively prevents water vapor permeation and electrode damage, improving the reliability and longevity of the light-emitting device by reducing built-in electric field effects and maintaining electrode integrity under harsh environmental conditions.
Implementation Method 1
The insulating material may include silicon oxide (SiO2), aluminum oxide (Al2O3), or a combination thereof... the passivation layer is disposed on the insulating layer... to prevent water vapor ingress
Implementation Method 2
utilizing silicon-rich insulating materials and silicon nitride-based passivation layers to reduce built-in electric fields
Data Source
AI summary
A light-emitting device includes a semiconductor light-emitting stack, first and second electrodes, an insulating layer, and a passivation layer. Each of the first and second electrodes is disposed on the semiconductor light-emitting stack. The insulating layer at least partially covers the semiconductor light-emitting stack. The passivation layer is disposed on the insulating layer, and covers the semiconductor light-emitting stack and a side surface of each of the first and second electrodes, to expose an upper surface of each of the first and second electrodes. The first electrode and the second electrode are separated by a distance that is greater than 0 μm and that is not greater than 80 μm.