Semiconductor LED Lead Frame with Insulator for Heat Dissipation
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Solution Overview
Problem
Conventional semiconductor light emitting devices face challenges in achieving uniform optical characteristics due to weak adhesion between epoxy resin and resin portion, leading to peeling issues and difficulties in controlling light directivity, and they struggle with heat radiation and die molding due to limited thermal conductivity and substrate damage.
Innovation Solution
A semiconductor light emitting device with a lead frame made of high thermal conductivity metal, surrounded by an insulator with a thickness not exceeding the lead frame, allowing for efficient heat radiation and die molding, and incorporating a sealing resin that can be molded into specific shapes to ensure intended optical characteristics, such as a dome or cylindrical shape, using die or dam-sheet molding to prevent peeling and variations in resin sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy resin is used for sealing LED chip and metal wire, then sealing function is achieved, but adhesion force is weak causing peeling between epoxy resin and resin portion
Solution Approach 1:
A primer layer is introduced as an intermediary between the resin portion and epoxy resin. The primer enhances adhesion by chemically bonding to both substrates, preventing peeling between the epoxy resin and resin portion while maintaining the sealing function.
Solution Approach 2:
The sealing structure uses a composite material system consisting of resin portion, primer layer, and epoxy resin. This multi-layer composite structure combines the advantages of each material to achieve both strong adhesion and effective sealing.
2Manufacturing precision
If resin portion protrudes on main surface of lead frame, then shape control is improved, but die molding becomes difficult due to clamping issues
Solution Approach 1:
The resin portion is segmented into multiple regions with different functions: a first region that protrudes for shape control and optical characteristics, and a second region that is flush with the lead frame surface for die molding compatibility. This segmentation allows both shape control and easy die molding.
Solution Approach 2:
Different regions of the resin portion have different geometric properties tailored to their specific functions. The protruding region provides optical control while the flush region enables proper die clamping, achieving local optimization of both shape control and manufacturability.
3Ease of manufacture
If conventional lead frame structure is used, then manufacturing simplicity is maintained, but heat radiation capability is insufficient
Solution Approach 1:
The lead frame structure transitions from a conventional two-dimensional planar configuration to a three-dimensional structure with elevated regions and varied thickness. This dimensional change increases the heat radiation surface area and improves thermal management while maintaining manufacturing simplicity through standard lead frame fabrication processes.
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 enables excellent heat radiation and consistent optical characteristics, preventing peeling and resin variations, while allowing for efficient production and improved solder wettability, reducing thermal degradation and extending device life.
Implementation Method 1
a sealing resin molded by die molding or dam-sheet molding so as to completely cover the semiconductor light emitting element and the metal wire
Implementation Method 2
a lead frame including a plate-like semiconductor light emitting element mounting portion having a semiconductor light emitting element mounted on a main surface
Data Source
AI summary
A semiconductor light emitting device that is excellent in radiating heat and that can be molded into a sealing shape having intended optical characteristics by die molding is provided. The semiconductor light emitting device includes: a lead frame including a plate-like semiconductor light emitting element mounting portion having an LED chip mounted on a main surface, and a plate-like metal wire connecting portion extending over a same plane as the semiconductor light emitting element mounting portion; a metal wire electrically connecting the LED chip and the metal wire connecting portion; a thermosetting resin molded by die molding or dam-sheet molding so as to completely cover the LED chip and the metal wire; and a resin portion provided to surround the lead frame and having the thickness not greater than the thickness of the lead frame.