UV LED Package Coating Layout for Light Extraction and Moisture Barrier
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Solution Overview
Problem
Semiconductor light emitting device packages face challenges in achieving reliable light extraction efficiency and protection from external moisture and gases, particularly when emitting ultraviolet light, due to limitations in existing packaging structures.
Innovation Solution
A semiconductor light emitting device package is designed with a circuit board, a light emitting diode chip configured to emit ultraviolet light, underfill resin covering the side surface of the chip, and a passivation layer extending over the underfill resin, using materials like fluoropolymer and aluminum oxide to enhance light output and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging structures are used for ultraviolet LED chips, then the device can be manufactured with standard processes, but light extraction efficiency is insufficient and protection from moisture and gases is inadequate
Solution Approach 1:
The patent employs composite materials including underfill resin (with fluoropolymer) for moisture barrier protection and passivation layer (with aluminum oxide) for enhanced chemical resistance. This combination of materials provides superior protection against moisture and gases while maintaining structural integrity, resolving the contradiction between reliability and device complexity by using material composition rather than structural complexity.
2Reliability
If the passivation layer is placed close to the semiconductor stack structure, then the protection coverage is maximized, but light extraction efficiency is reduced due to interference with the light path
Solution Approach 1:
The patent applies local quality by positioning the passivation layer to cover specific areas (electrode structures and connection bumps) rather than uniformly covering the entire chip surface. The underfill resin is applied selectively around the chip periphery. This localized application provides protection where needed while leaving the light extraction path clear, resolving the contradiction between protection coverage and light extraction efficiency.
Solution Approach 2:
The underfill resin acts as an intermediary material between the semiconductor chip and the external environment. It provides moisture barrier protection around the chip edges and supports the passivation layer, enabling the passivation layer to be positioned optimally for light extraction while maintaining comprehensive protection coverage through the combined system.
3Illumination intensity
If standard underfill resin is used, then the manufacturing process is simple, but ultraviolet light transmittance is insufficient, reducing light extraction efficiency
Solution Approach 1:
The patent changes the chemical composition parameters of the underfill resin by incorporating fluoropolymer, which has superior ultraviolet transmittance properties compared to conventional resins. This parameter change in material composition directly improves light extraction efficiency while the manufacturing process remains compatible with existing underfill application techniques, balancing performance improvement with ease of manufacture.
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 and reliability by using an underfill resin with high ultraviolet transmittance and a passivation layer to protect the device from external factors, ensuring consistent performance and longevity.
Implementation Method 1
an underfill resin disposed on the upper pad of the circuit board, covering a side surface of the LED chip and including a fluoropolymer
Implementation Method 2
a passivation layer covering the second surface of the LED chip and the underfill resin, extending onto an upper surface of the circuit board, and including at least aluminum oxide
Data Source
AI summary
A semiconductor light emitting device package includes a circuit board with an upper pad, a light emitting diode chip on the circuit board and having a first surface facing the circuit board and a second surface opposing the first surface, and the light emitting diode chip including a substrate, a semiconductor stack structure on the substrate that emits ultraviolet light, and electrodes connected to the semiconductor stack structure, connection bumps between the circuit board and the light emitting diode chip, the connection bumps connecting the upper pad and the electrodes, an underfill resin on the upper pad of the circuit board and covering at least a portion of a side surface of the light emitting diode chip, and a passivation layer on the light emitting diode chip and the underfill resin, the passivation layer covering the underfill resin and being spaced apart from the semiconductor stack structure.