Lead Frame Reflection Layer Sulfuration Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lead frames used in semiconductor devices experience a decrease in reflectivity due to sulfuration and oxidation over long-term use, especially when exposed to the environment or sealed with resin, which affects the emission efficiency of light-emitting devices.
Innovation Solution
A lead frame design featuring a reflection layer coated with a characteristic sustaining layer, typically made of inorganic or organic materials like fluorine-based, silicone-based, triazole-based, or Au thin film materials, which isolates the reflection layer from external substances, preventing degradation and maintaining reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the silver coating is exposed outside before mounting the light emitting device, then the light emission efficiency is enhanced, but the reflectivity of the silver lowers due to sulfuration and/or oxidation
Solution Approach 1:
The patent applies a thin film protective layer (characteristic sustaining layer) over the silver reflection layer. This thin film isolates the silver from environmental exposure (sulfur and oxygen) while allowing light to pass through, thus maintaining both high reflectivity and light emission efficiency. The protective layer acts as a barrier that prevents sulfuration and oxidation without significantly affecting optical performance.
Solution Approach 2:
The patent creates a composite structure consisting of the silver reflection layer combined with a protective characteristic sustaining layer. This composite material approach allows the silver to provide high reflectivity while the protective layer provides chemical stability and resistance to sulfuration/oxidation. The combination achieves both high light emission efficiency and long-term reliability.
2Loss of energy
If the silver coating is exposed to enhance light reflection, then emission efficiency improves, but the silver coating is sulfurated and/or oxidized by sulfur and/or oxygen penetrated through the resin due to long-term use
Solution Approach 1:
The patent applies the characteristic sustaining layer in advance, before the light emitting device is mounted and before long-term use begins. This preliminary protective action prevents sulfur and oxygen from reaching the silver layer during the device's operational life, thereby maintaining reflectivity and emission efficiency over extended periods without degradation.
Solution Approach 2:
The thin film protective layer serves as a permanent barrier that isolates the silver reflection layer from environmental contaminants throughout the device's operational lifetime. This continuous protection ensures that the silver coating maintains its reflectivity and that the light emitting device sustains high emission efficiency over long-term use.
3Reliability
If a protective layer is added to prevent sulfuration and oxidation, then reflectivity is maintained, but the device complexity increases
Solution Approach 1:
The patent employs a thin film protective layer that adds minimal structural complexity while effectively preventing sulfuration and oxidation. The thin film nature of the protective layer means it adds little thickness or mechanical complexity to the overall device structure, while still providing robust chemical protection to maintain silver reflectivity over time.
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 the deterioration of the reflection layer's characteristics over time, enhancing the bonding and thermal conductivity while maintaining high reflectivity, thus improving the performance and longevity of light-emitting devices.
Implementation Method 1
the reflectivity of the silver lowers due to sulfuration and/or oxidation
Implementation Method 2
the reflectivity of the silver lowers due to sulfuration and/or oxidation
Implementation Method 3
light emitted from the light-emitting device toward the lead frame can be efficiently reflected on the region with the silver coating to enhance the emission efficiency
Data Source
AI summary
A lead frame includes a base material, a reflection layer formed on a part of the base material, and a characteristic sustaining layer formed at least on the reflection layer to cover the reflection layer for sustaining a characteristic of the reflection layer by isolating the reflection layer from an outside. The reflection layer includes the characteristic to exhibit a predetermined reflectivity to light with a predetermined wavelength, and the characteristic sustaining layer prevents a decrease in the reflectivity of the reflection layer and transmits light reflected by the reflection layer.