Light Emitting Device Lead Frame Protrusion Heat Management
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Solution Overview
Problem
Existing light emitting devices face challenges in achieving high power efficiency and effective heat dissipation due to the exposure of lead frames with low reflectance, which affects the luminous efficiency and heat management.
Innovation Solution
The design incorporates lead frames with protrusions that have exposed upper surfaces for mounting light emitting elements, where at least half of the upper surface is covered, and the use of a resin to fill gaps between protrusions, reducing lead frame exposure and enhancing reflectance, while allowing for efficient heat dissipation through the lead frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the lead frame is exposed at the bottom surface of the recess to facilitate heat dissipation, then heat dissipation is improved, but the reflectance is reduced due to low reflectance of the metal frame
Solution Approach 1:
The invention applies local quality by creating protrusions with exposed upper surfaces at specific locations where heat dissipation is critical, while the resin portion covers other areas to maintain high reflectance. The lead frame protrusions are strategically positioned to expose only the necessary areas for heat management while minimizing the impact on overall reflectance.
Solution Approach 2:
The lead frame is segmented into multiple protrusions rather than a continuous exposed surface. This segmentation allows selective exposure of heat-generating areas while maintaining resin coverage in areas where reflectance is more critical, thus balancing heat dissipation and light reflection needs.
2Use of energy by moving object
If the lead frame is covered with resin to increase reflectance, then power efficiency is improved, but heat dissipation capability is reduced
Solution Approach 1:
The resin portion is applied selectively to cover areas where high reflectance is needed, while leaving the upper surfaces of lead frame protrusions exposed in areas where heat dissipation is prioritized. This localized application of resin creates different functional zones within the same package structure.
Solution Approach 2:
The package structure is segmented into resin-covered areas and exposed lead frame areas. The protrusions create distinct zones that separate the optical function (reflected by resin) from the thermal function (dissipated by exposed metal), allowing both requirements to be satisfied simultaneously.
3Ease of manufacture
If the light emitting element is mounted on a flat surface, then mounting is simple, but heat dissipation efficiency is reduced compared to protruding surfaces
Solution Approach 1:
The protrusions are pre-formed on the lead frame before the light emitting element is mounted. This preliminary structuring creates ready-made mounting surfaces that inherently provide both mechanical support and thermal pathways, eliminating the need for additional heat dissipation structures while maintaining mounting simplicity.
Solution Approach 2:
The protrusions serve multiple functions simultaneously: they provide mechanical mounting surfaces for the light emitting element, act as heat sinks for thermal management, and create electrical connection points. This multi-functionality simplifies the overall structure while improving heat dissipation.
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 configuration improves light emitting efficiency by increasing reflectance and facilitates effective heat management, leading to higher power efficiency and reliability in light emitting devices.
Implementation Method 1
light emitted from the light emitting element and reflected by the side walls or the bottom surface of the recess can be emitted outside of the light emitting device
Implementation Method 2
heat management
Data Source
AI summary
A light emitting device includes a package and a light emitting element. The package includes a resin portion and at least one lead frame arranged in the resin portion. The at least one lead frame has at least one protrusion which is surrounded by the resin portion and which has an upper surface exposed from the resin portion. The light emitting element is mounted on the upper surface of the at least one protrusion and is electrically connected to the at least one lead frame. At least a half area of the upper surface is covered with the light emitting element.