UVLED Package Groove Structure for Thermal Stress Buffering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional UVLED packages face reliability issues due to organic package adhesive degradation from UV exposure and thermal mismatch between substrates, leading to reduced service life and device failure.
Innovation Solution
The UVLED package structure incorporates a groove structure on the package cover filled with an organic binder, which acts as a buffer for thermal stress and protects against UV degradation, using a ceramic or plastic support with a cup surrounding the LED chip and a reflective or absorption layer to enhance adhesion and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic package adhesive is used to bond the package cover to the LED chip, then bonding is achieved, but the adhesive degrades due to UV exposure and thermal stress, reducing reliability
Solution Approach 1:
The package structure is divided into distinct functional zones: a UV-transparent or UV-resistant package cover, an organic binder layer for bonding, and a reflective layer. This segmentation allows each component to be optimized for its specific function, with the package cover protecting against UV while the binder provides bonding.
Solution Approach 2:
The organic binder serves as an intermediary layer between the package cover and the LED chip substrate. It mediates the bonding function while also providing stress relief due to its flexibility, preventing direct transmission of thermal expansion stresses between the rigid package cover and substrate.
2Object-affected harmful factors
If inorganic materials like glass are used to replace organic package adhesive, then UV resistance is improved, but bonding between substrate and glass becomes difficult and CTE mismatch occurs
Solution Approach 1:
The organic binder acts as an intermediary between the inorganic package cover (glass or quartz) and the substrate. This intermediary layer provides both bonding functionality and compliance with CTE mismatch, allowing the rigid inorganic cover to be securely attached while accommodating thermal expansion differences.
Solution Approach 2:
The package structure employs a composite design combining inorganic materials (UV-resistant glass or quartz cover) with organic materials (binder layer). This composite approach leverages the UV resistance of inorganic materials while utilizing the bonding capability and stress compliance of organic materials.
3Strength
If AuSn eutectic package is adopted for bonding, then strong bonding is achieved, but new machinery and processes are required for plating metals
Solution Approach 1:
The organic binder provides sufficient bonding strength for the application without requiring permanent metallization processes. This approach accepts a less durable but easier-to-apply bonding method, eliminating the need for complex plating machinery and processes while achieving adequate bonding for the package's service life.
4Illumination intensity
If the package cover is made UV-transparent to allow UV light output, then light transmission is improved, but the organic binder degrades from UV exposure
Solution Approach 1:
The package structure applies local quality by making different regions have different UV properties. The package cover is designed to be UV-transparent or UV-resistant depending on the specific wavelength requirements, while the organic binder is positioned and formulated to resist UV degradation, creating localized functional zones with optimized properties.
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 extends the service life and reliability of UVLED packages by preventing organic binder degradation and mitigating thermal expansion mismatches, ensuring consistent performance in various environments.
Implementation Method 1
the groove structure surface is provided with a reflective layer or an absorption layer
Implementation Method 2
the groove structure surface is provided with a reflective layer or an absorption layer
Implementation Method 3
the organic binder layer can serve as a buffer layer for stress release due to small Young modulus, which resolves mismatch in coefficient of thermal expansion
Data Source
AI summary
A light-emitting diode (LED) package structure includes: a support; an LED chip; and a package cover, wherein: a support circuit is formed over the support; the LED chip is arranged over the support and electrically coupled to the support circuit; a lower surface periphery of the package cover is provided with a groove structure filled with organic binder; and the package cover is arranged over the LED chip and connected to the support via the organic binder.