LED Submount Meniscus Control Features for Optical Loss Reduction
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Solution Overview
Problem
Conventional LED packaging methods suffer from optical losses due to the reflection and absorption of light by the reflective cup, leading to inefficient light emission and reduced performance.
Innovation Solution
A submount with meniscus control features on a substrate is used to mount the LED, featuring a die attach pad and encapsulant regions defined by meniscus control features, allowing for precise encapsulation and wirebond connections, and potentially including wavelength conversion materials, to enhance light output and reduce optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective cup is used to mount the LED, then mechanical support and electrical connection are provided, but optical losses occur due to reflection and absorption of light
Solution Approach 1:
The patent removes the reflective cup component entirely from the packaging structure. Instead of using a reflective cup to mount the LED, the invention employs a substrate with a die attach pad that directly supports the LED chip, eliminating the source of optical losses caused by the reflective cup's reflection and absorption properties.
Solution Approach 2:
Rather than using a reflective cup that reflects light away from the desired path, the patent inverts the approach by using a substrate and encapsulant system that directly transmits and protects the light path. The meniscus control features and encapsulants are designed to manage light output without the intermediate reflective surfaces that cause losses.
2Illumination intensity
If conventional packaging methods are used, then environmental protection is provided, but light output efficiency is reduced due to optical losses
Solution Approach 1:
The patent introduces encapsulants as intermediary materials between the LED chip and the external environment. These encapsulants provide environmental protection while being optically transparent or designed to enhance light extraction, thus protecting the LED without significantly reducing light output efficiency like conventional reflective cups do.
Solution Approach 2:
The patent changes the optical parameters of the packaging materials by using encapsulants with specific refractive indices and optical properties that enhance light extraction and transmission. The meniscus control features are designed to optimize the optical interface between the encapsulant and air, improving illumination intensity while maintaining environmental protection.
3Manufacturing precision
If meniscus control features are added to the substrate, then encapsulation precision is improved, but manufacturing complexity increases
Solution Approach 1:
The meniscus control features are pre-formed on the substrate during substrate fabrication, before the encapsulant application step. This preliminary structuring of the substrate surface allows for precise encapsulation geometry to be achieved without adding complex manufacturing steps later in the process.
Solution Approach 2:
The meniscus control features utilize the natural surface tension and capillary action of the encapsulant material to self-form precise encapsulation geometries. When the encapsulant is applied, it automatically conforms to the meniscus control features, creating precise encapsulation without requiring additional precision manufacturing equipment or complex processing steps.
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 output by minimizing optical losses associated with traditional reflective cup mounting, resulting in a more efficient and effective LED packaging method that approximates an ideal point source of light.
Implementation Method 1
A first meniscus control feature on the substrate surrounds the die attach pad and defines a first encapsulant region of the upper surface of the substrate. A second meniscus control feature on the substrate surrounds the first encapsulant region and defines a second encapsulant region of the upper surface of the substrate.
Data Source
AI summary
A submount for mounting an LED chip includes a substrate, a die attach pad configured to receive an LED chip on an upper surface of the substrate, a first meniscus control feature on the substrate surrounding the die attach pad and defining a first encapsulant region of the upper surface of the substrate, and a second meniscus control feature on the substrate surrounding the first encapsulant region and defining a second encapsulant region of the upper surface of the substrate. The first and second meniscus control features may be substantially coplanar with the die attach pad. A packaged LED includes a submount as described above and further includes an LED chip on the die attach pad, a first encapsulant on the substrate within the first encapsulant region, and a second encapsulant on the substrate within the second encapsulant region and covering the first encapsulant. Method embodiments are also disclosed.