LED Package Lens Structure for Thermal Stress and Crack Resistance
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Solution Overview
Problem
Conventional resin-structure deep ultraviolet (DUV) LED packages face reduced light extraction efficiency due to UV-induced transparency decline in resin materials, and glass-lens-structure packages are prone to thermal stress and cracking, increasing packaging costs.
Innovation Solution
The LED package incorporates a packaging substrate with an LED chip and a light-transmissible unit featuring an indentation-defined by a curved or inclined surface, reducing edge stress and cracking risk through arc-shaped connections, while maintaining light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin-structure is used for DUV LED packaging, then the packaging cost is reduced, but the light extraction efficiency deteriorates due to UV-induced transparency decline
Solution Approach 1:
The patent employs a composite structure combining resin material with a microlens array. The microlens array is integrated into the resin packaging substrate to enhance light extraction efficiency while maintaining the cost benefits of resin packaging. This composite approach allows the resin to provide low-cost packaging while the microlens array compensates for the transparency degradation issue.
2Reliability
If a glass-lens-structure is used for DUV LED packaging, then the light extraction efficiency is maintained, but the structural strength deteriorates due to thermal stress and cracking risk
Solution Approach 1:
The patent modifies the geometric parameters of the packaging structure by introducing a microlens array with specific curvature radii and pitch dimensions. This parameter optimization enables the resin structure to achieve light extraction efficiency comparable to glass while maintaining the inherent strength advantages of resin materials.
3Ease of manufacture
If a right angular portion is used in the lens structure, then the manufacturing is simplified, but the stress concentration increases causing cracking
Solution Approach 1:
The patent replaces right angular portions with curved surfaces in the microlens array structure. The microlenses are formed with spherical or aspherical surfaces that eliminate sharp corners and edges, thereby distributing stress more evenly and preventing stress concentration that would lead to cracking under thermal load.
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 reduces edge stress and cracking risks, enhancing the durability and cost-effectiveness of the LED package by distributing stress evenly and maintaining light extraction efficiency.
Implementation Method 1
the indentation-defining wall includes a base part, a peripheral part, and a first connecting part that interconnects the base part and the peripheral part and that includes one of a curved surface, an inclined flat surface, and a combination thereof
Data Source
AI summary
A light-emitting diode (LED) package includes a packaging substrate having a first surface, an LED chip disposed on the first surface, and a light-transmissible unit disposed on the first surface and formed with an indentation defined by an indentation-defining wall which cooperates with the first surface to form a cavity in which the LED chip is enclosed. The indentation-defining wall includes a base part, a peripheral part, and a first connecting part that interconnects the base part and the peripheral part and that includes one of a curved surface, an inclined surface, and a combination thereof. Other two LED packages are also disclosed.