LED Package Heat Sink and Reflector Design
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Solution Overview
Problem
Conventional light emitting device packages suffer from low heat radiation efficiency and optical characteristic deterioration due to inadequate heat dissipation and resin degradation, making it difficult to mount high-power LEDs and maintain optical performance.
Innovation Solution
A light emitting device package design featuring a thick copper lead frame acting as a heat sink, a metallic reflector with a hollow portion for improved light reflection, and a resin body with an insulation layer and protrusions for enhanced adhesion and protection, eliminating the need for a separate heat sink and reducing resin exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resin body is used to package the light emitting device, then the device is protected and mounted, but heat radiation efficiency is reduced and optical characteristics deteriorate
Solution Approach 1:
The resin body is segmented into multiple layers: a first resin layer that does not contact the light-emitting chip (reducing heat accumulation and discoloration), and a second resin layer that provides sealing protection. This segmentation allows the protective function to be maintained while reducing harmful thermal effects on the optical components.
Solution Approach 2:
A reflective layer is introduced as an intermediary between the light-emitting chip and the resin body. This reflective layer has high light reflectance and serves as a thermal barrier, preventing heat from the chip from directly heating the resin body, thereby maintaining heat radiation efficiency while preserving device protection.
2Duration of action of moving object
If the resin body is exposed to light for a long time, then the device operates continuously, but the resin body is discolored or deteriorated
Solution Approach 1:
The resin body is divided into a first resin layer positioned away from the light-emitting chip and a second resin layer for sealing. The first resin layer is not exposed to intense light and heat from the chip, preventing discoloration and deterioration while allowing continuous operation. This layered structure maintains optical characteristics over extended periods.
Solution Approach 2:
The reflective layer acts as an intermediary that protects the resin body from direct exposure to light and heat from the light-emitting chip. By reflecting light away from the resin body, this layer prevents photo-degradation and discoloration, enabling continuous operation without compromising optical characteristics.
3Illumination intensity
If the resin body area reflecting light is reduced, then light reflectance is improved, but device structure becomes more complex
Solution Approach 1:
A dedicated reflective layer is introduced as an intermediary component between the light-emitting chip and the resin body. This layer is specifically designed with high light reflectance properties, taking over the light reflection function from the resin body. While this adds a component, it simplifies the overall design by providing a specialized solution for light management.
Solution Approach 2:
The package structure uses composite materials including the reflective layer with specific optical properties and the resin body with optimized composition. The reflective layer can be made from materials with high light reflectance, while the resin body focuses on protection and sealing functions, creating a composite structure that optimizes both optical performance and structural integrity.
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 design enhances heat radiation efficiency, maintains optical performance, and reduces manufacturing costs by integrating the heat sink into the lead frame, while preventing resin degradation and improving reflection efficiency.
Implementation Method 1
a metallic reflector which is disposed on the lead frame, has a hollow portion in which the light emitting device is disposed, reflects light emitted from the light emitting device
Implementation Method 2
a thick copper lead frame acting as a heat sink
Data Source
AI summary
A light emitting device package may be provided that includes: a lead frame; a light emitting device disposed on the lead frame; a metallic reflector which is disposed on the lead frame, has a hollow portion in which the light emitting device is disposed, reflects light emitted from the light emitting device, and is formed by a mold; and a resin body which surrounds the lead frame and the reflector. The resin body includes an insulation layer disposed between the lead frame and the reflector, and a protrusion disposed on the reflector.