UV LED Package Structure With Fluororesin Cover and Indentation Locking
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Solution Overview
Problem
Conventional deep-ultraviolet LED packaging structures are large in size and costly due to their U-shape design, leading to reduced light emission efficiency and potential damage from deep ultraviolet light, and inorganic encapsulants like fluororesins have poor adhesion, causing detachment and void formation.
Innovation Solution
A packaged ultraviolet light-emitting device with a support member featuring indentations and an encapsulating cover made from a fluorine-containing resin, which is tightly attached to the chip and support member, eliminating gaps and enhancing light transmission and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a U-shape support base is used to form a cavity for accommodating the LED chip, then the LED chip can be securely mounted, but the overall thickness increases and the packaging structure becomes large in size
Solution Approach 1:
The support base transitions from a conventional planar structure to a three-dimensional structure with indentations extending downward from the top surface. These indentations create mounting cavities without requiring the entire base to be thick, thus reducing overall thickness while maintaining secure mounting capability.
Solution Approach 2:
The support base is segmented into different functional regions: flat top surface areas for mounting components and indentation areas for forming cavities. This segmentation allows the base to perform multiple functions with reduced overall thickness.
2Device complexity
If a gap exists between the LED chip and the cover due to the U-shape section, then the cavity structure is formed, but light emission efficiency decreases due to multiple refraction interfaces
Solution Approach 1:
The refractive index parameter of the encapsulating material is changed from conventional silicone encapsulant to fluororesin, which has a refractive index closer to that of the LED chip substrate. This reduces the refractive index difference at the interface, minimizing total internal reflection and improving light extraction efficiency.
3Reliability
If silicone encapsulant is used to encapsulate the LED chip, then the chip is protected, but the encapsulant breaks after long-term irradiation by deep ultraviolet light
Solution Approach 1:
The material composition parameter of the encapsulant is changed from silicone-based organic material to fluororesin, which has superior resistance to deep ultraviolet light irradiation. This material substitution maintains protective function while dramatically extending service life under UV exposure.
4Loss of energy
If fluororesin is used as encapsulant, then transmittance for ultraviolet light is improved, but adhesion to components is poor causing detachment and void formation
Solution Approach 1:
The support base is designed with different surface characteristics in different locations: the top surface provides a stable mounting platform, while the downward-extending indentations create localized adhesion zones. The fluororesin encapsulant is contained within these indentations, creating strong localized bonding interfaces between the encapsulant, support base, and LED chip.
Solution Approach 2:
The adhesion interface is extended from a two-dimensional surface contact to a three-dimensional configuration where the fluororesin fills and bonds within the vertical indentations. This vertical dimension provides increased bonding surface area and mechanical interlocking, compensating for the inherently poor adhesion properties of fluororesin.
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 results in a smaller, more efficient, and cost-effective packaged ultraviolet light-emitting device with improved light emission and stability, as the encapsulating cover extends into the indentations, ensuring secure attachment and reducing total reflection.
Implementation Method 1
the light generated by the deep-ultraviolet LED chip 104 is required to travel from the substrate thereof (e.g. a sapphire substrate having a refractive index of 1.76) first to the air in the gap and then to the cover 102 (having a refractive index of 1.40 attributed to its quartz glass material), thus lowering the light emission efficiency
Data Source
AI summary
A packaged ultraviolet light-emitting device includes a support member, at least one ultraviolet light-emitting chip, and an encapsulating cover. The support member has opposite top and bottom surfaces, a side surface interconnecting the top and bottom surfaces, and at least one indentation. The ultraviolet light-emitting chip is disposed on the top surface of the support member. The encapsulating cover is made from a fluorine-containing resin, and is disposed over and in contact with the ultraviolet light-emitting chip and the top surface and the indentation of the support member. The encapsulating cover extends into the indentation. A production method of the packaged ultraviolet light-emitting device is also disclosed.