Overlapping Lead Frame Structure for LED Heat Dissipation
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Solution Overview
Problem
Conventional light emitting devices face challenges in durability, heat dissipation, and resistance to high pressure, with the need for improved mechanical strength and prevention of tarnishing of Ag-plated lead frames due to sulfuration, especially as they require higher output power and increased heat management.
Innovation Solution
A light emitting device design featuring a package with first and second lead frames made of different metals, where the lead frames are partially overlapped and embedded in a resin, providing enhanced mechanical strength and heat dissipation, and the second lead frame is coated with a metal layer for improved electrical conductivity and sulfuration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single lead frame is used, then the device structure is simple, but the mechanical strength and heat dissipation are insufficient
Solution Approach 1:
The patent combines multiple lead frames (first lead frame with Ag plating and second lead frame with Al plating) into a single integrated structure. The lead frames are overlapped and embedded together in the resin package, creating a composite structure that enhances mechanical strength and heat dissipation while maintaining electrical connectivity through the overlapping configuration.
2Reliability
If Ag-plated lead frame is used, then electrical conductivity is good, but tarnishing occurs due to sulfuration with aging
Solution Approach 1:
The patent divides the lead frame structure into two separate segments: a first lead frame with Ag plating for electrical connection purposes and a second lead frame with Al plating for structural support and sulfuration resistance. This segmentation allows each component to perform its specialized function without compromising the other, preventing tarnishing while maintaining conductivity.
3Power
If higher output power is required, then light amount increases, but heat dissipation becomes more difficult
Solution Approach 1:
The patent employs a composite material structure where lead frames with different metal platings (Ag and Al) are overlapped and embedded in resin. The Al-plated portions provide enhanced thermal conductivity for heat dissipation, while the Ag-plated portions maintain electrical conductivity. This composite approach enables the device to handle higher output power and heat generation effectively.
Data Source
AI summary
A light emitting device includes a light emitting element and a package. The package includes a first lead frame, a second lead frame, and a resin. The first lead frame has a first surface on which the light emitting element is provided. The first lead frame has a first overlap portion. The second lead frame is spaced apart from the first lead frame and has a second overlap portion. The first overlap portion and the second overlap portion overlap at an overlap position so that the first lead frame extends from the overlap position toward a first direction and a second direction opposite to the first direction and so that the second lead frame extend from the overlap position toward a third direction and a fourth direction opposite to the third direction as viewed along a line substantially perpendicular to the first surface.