Self-Forming LED Encapsulation Dome via Surface Tension
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Providing a reproducible encapsulation structure for light-emitting diodes (LEDs) without the use of separate containment dams, especially in applications where a reflector cup is not utilized, is challenging due to the spreading of silicone encapsulant before it sets, which affects the consistency and efficiency of the light source.
Innovation Solution
A droplet of encapsulating material with surface tension is used, where the periphery is defined by a predefined feature on the substrate, such as a recess or raised ring, to contain and shape the silicone droplet into a reproducible dome shape, ensuring consistent encapsulation without the need for separate containment dams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a droplet of silicone encapsulating material is deposited over the LED die, then the die is protected and light efficiency is improved, but the silicone spreads out excessively on the substrate surface before solidifying, resulting in poor reproducibility of the encapsulation dome shape
Solution Approach 1:
A predefined feature (such as a recess or raised ring) is created on the substrate surface before depositing the silicone encapsulating material. This preliminary structural preparation provides a boundary that guides the silicone droplet's perimeter, ensuring consistent dome formation and preventing excessive spreading before the silicone solidifies.
2Reliability
If a reflector cup is used to contain the silicone encapsulant, then reproducible encapsulation is achieved, but the device complexity increases and the profile height is increased
Solution Approach 1:
The containment function previously performed by a separate reflector cup structure is extracted and integrated directly into the substrate surface through a predefined feature. This eliminates the need for a distinct containment structure, reducing overall device complexity while maintaining the ability to provide reproducible encapsulation domes.
Solution Approach 2:
The substrate and containment structure are merged into a single integrated component. The predefined feature on the substrate surface serves dual purposes: providing mechanical support for the LED die and defining the perimeter boundary for the silicone encapsulation dome, thereby eliminating the need for a separate reflector cup.
3Shape
If the silicone viscosity is increased to prevent spreading, then the droplet maintains its shape better, but the material's ability to conform to the die and provide proper encapsulation is reduced
Solution Approach 1:
Instead of modifying the silicone viscosity to control droplet spreading, a predefined feature is prepared on the substrate surface beforehand. This feature creates a physical boundary that contains the silicone droplet at the desired perimeter, allowing the silicone to maintain optimal viscosity for conforming to the die while still preventing excessive spreading.
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 method allows for a highly reproducible and efficient encapsulation of LEDs, maintaining light source performance and cost-effectiveness by utilizing the surface tension of the liquid precursor material to form a self-contained dome that solidifies into a consistent shape, enhancing the reliability and efficiency of LED light sources.
Implementation Method 1
The droplet is formed from a liquid precursor material that is characterized by a surface tension
Data Source
AI summary
A light source including a die, substrate, and droplet of encapsulating material is disclosed. The die includes a semiconductor light-emitting device that is connected to first and second conducting traces on a first surface of the substrate. The droplet of encapsulate material overlies the die and is formed from a liquid precursor material that is characterized by a surface tension. The droplet has a periphery in contact with the first surface, the periphery having a shape determined by a predefined feature on the first surface and the surface tension of the liquid precursor material. The feature can include a recess in the first surface or a ring having an area that is raised above the first surface.