Borosilicate Glass Overcoat for LED Silver Conductor Corrosion
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Solution Overview
Problem
Existing light-emitting devices with silver conductor layers face corrosion issues leading to reduced light reflectance and require high-temperature processing, which increases production load and reduces reliability.
Innovation Solution
A light-emitting device with a borosilicate glass overcoat layer is used to protect the silver conductor layer, enhancing light reflectance and corrosion resistance, and allowing for co-firing with the silver conductor layer to reduce production complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a silver light reflection layer is used, then light reflectance is improved, but corrosion resistance deteriorates over time
Solution Approach 1:
A resin layer is introduced as an intermediary between the silver light reflection layer and the external environment. This resin layer acts as a protective barrier that prevents moisture and corrosive substances from reaching the silver layer, thereby maintaining both high light reflectance and corrosion resistance over time.
Solution Approach 2:
The device employs a composite structure combining silver material for high reflectance properties with resin material for corrosion protection. This composite approach allows the system to simultaneously achieve optical performance and environmental stability that neither material could provide alone.
2Illumination intensity
If alumina material is used for high reflectance, then light reflectance is improved, but manufacturing complexity increases due to high-temperature firing requirements
Solution Approach 1:
Instead of using expensive alumina material requiring high-temperature processing, the invention employs a more economical approach: a resin-coated silver layer. The resin layer provides sufficient protection for the silver to maintain reflectance without requiring extreme manufacturing conditions, thereby reducing production complexity and cost.
Solution Approach 2:
The invention changes the manufacturing parameters from high-temperature firing (required for alumina) to lower-temperature resin curing processes. This parameter change enables the use of silver-based reflectance layers while avoiding the substantial production load associated with high-temperature ceramic processing.
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 improves light extraction efficiency, prevents corrosion, and reduces production load by using a borosilicate glass overcoat layer that can be co-fired with the silver conductor layer, maintaining high reflectance and extending the device's service life.
Implementation Method 1
an overcoat layer is formed between the conductor layer and the light-emitting element, and the overcoat layer is a borosilicate glass which comprises... the solution improves light extraction efficiency, prevents corrosion
Implementation Method 2
a light reflection layer made of e.g. silver is formed on the substrate around the mounted LED chip. And, by such a light reflection layer, an emission from the LED chip radiated to the substrate side... is reflected to the forward direction thereby to improve the light extraction efficiency
Data Source
AI summary
Provided is a light-emitting device provided with a light reflection layer which has a high light reflectivity and which is less susceptible to deterioration of the reflectivity due to corrosion, and having an improved light extraction efficiency.A light-emitting device comprising a substrate having a conductor layer formed on its surface and a light-emitting element disposed on the conductor layer, characterized in that an overcoat layer is formed between the conductor layer and the light-emitting element, and the overcoat layer is a borosilicate glass which comprises, as represented by mol % based on oxides, from 62 to 84% of SiO2, from 10 to 25% of B2O3, from 0 to 5% of Al2O3 and from 0 to 5% in total of at least one of Na2O and K2O, provided that the total content of SiO2 and Al2O3 is from 62 to 84%, and may contain from 0 to 10% of MgO and at least one of CaO, SrO and BaO in a total content of at most 5%.