LED Package Heat-Spreading Submount With Molded Lens
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Solution Overview
Problem
Conventional LED packages face challenges in thermal management and manufacturing complexity, particularly for high-power operations, where heat dissipation is inefficient due to the use of separate metal reflectors and ceramic submounts that do not effectively conduct heat, leading to potential overheating and reduced package lifetime.
Innovation Solution
The development of LED packages with a submount featuring top and bottom surfaces equipped with thermally conductive elements that spread heat across the majority of the submount, combined with a lens molded directly over the LED for improved thermal management and optical protection, allowing for efficient heat dissipation and reduced manufacturing complexity through simultaneous package formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a separate metal reflector is used to direct light, then light direction control is improved, but manufacturing complexity and assembly steps increase
Solution Approach 1:
The patent combines the reflector and submount into a single integrated component. The submount includes a reflective surface that directs light upward while also providing mechanical support and electrical connection functions, eliminating the need for a separate metal reflector piece and reducing assembly steps.
Solution Approach 2:
The submount is designed to perform multiple functions simultaneously: it provides mechanical support for the LED chip, conducts heat away from the LED, provides electrical connection through conductive elements, and directs light through its reflective surface. This multi-functional design reduces the overall number of components needed.
2Strength
If ceramic submounts are used for high power operations, then mechanical robustness is improved, but heat dissipation efficiency deteriorates
Solution Approach 1:
The submount is constructed as a composite structure with a ceramic base providing mechanical robustness and a metal layer (such as copper or aluminum) deposited on top providing high thermal conductivity. This composite design combines the advantages of both materials: the ceramic provides strength and insulation while the metal layer efficiently conducts heat away from the LED.
Solution Approach 2:
The submount features localized thermal management with high thermal conductivity material concentrated in the heat spreader layer directly beneath the LED chip, while the surrounding ceramic structure provides mechanical support. The conductive elements are strategically positioned to create optimal heat flow paths from the LED junction through the submount.
3Ease of manufacture
If heat is localized below the LED chip, then manufacturing simplicity is improved, but package reliability deteriorates due to overheating
Solution Approach 1:
The heat spreader layer extends horizontally across the submount surface in addition to the vertical heat conduction path. This two-dimensional heat distribution approach spreads heat laterally across a larger area, increasing the effective heat dissipation surface while maintaining a simple planar submount structure that is easy to manufacture.
Solution Approach 2:
The submount is pre-designed with integrated heat spreading pathways and conductive elements positioned to actively conduct heat away from the LED chip as soon as it is generated. The reflective surface is pre-configured to direct light upward while the thermal pathways are pre-established in the submount structure, ensuring immediate heat management from the moment the LED operates.
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 solution enables efficient thermal dissipation, prolongs the operating life of LED packages, and simplifies the manufacturing process by integrating heat-spreading elements and optical protection, facilitating higher power operations without overheating and reducing production costs.
Implementation Method 1
Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light, and generally comprise one or more active layers of semiconductor material sandwiched between oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active layer where they recombine to generate light.
Implementation Method 2
The reflective cup may be filled with an encapsulant material 16 containing a wavelength conversion material such as a phosphor. Light emitted by the LED at a first wavelength may be absorbed by the phosphor, which may responsively emit light at a second wavelength.
Implementation Method 3
The entire assembly is then encapsulated in a clear protective resin 14, which may be molded in the shape of a lens to collimate the light emitted from the LED chip 12.
Implementation Method 4
An LED is included on one of the top elements such that an electrical signal applied to the top elements causes the LED to emit light. The electrically conductive elements also spread heat from the LED across the majority of the submount top surface.
Data Source
AI summary
An LED package comprising a submount having a top and bottom surface with a plurality of top electrically and thermally conductive elements on its top surface. An LED is included on one of the top elements such that an electrical signal applied to the top elements causes the LED to emit light. The electrically conductive elements also spread heat from the LED across the majority of the submount top surface. A bottom thermally conductive element is included on the bottom surface of said submount and spreads heat from the submount, and a lens is formed directly over the LED. A method for fabricating LED packages comprising providing a submount panel sized to be separated into a plurality of LED package submounts. Top conductive elements are formed on one surface of the submount panel for a plurality of LED packages, and LEDs are attached to the top elements. Lenses are molded over the LEDs and the substrate panel is singulated to separate it into a plurality of LED packages.