Light-Emitting Package Structure for Heat and Light Extraction
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Solution Overview
Problem
Current light-emitting device packages face challenges in achieving high light extraction efficiency and heat resistance while maintaining stability, as the sizes of these devices have decreased, requiring advancements in both light extraction and heat dissipation mechanisms.
Innovation Solution
The proposed solution involves a light-emitting device package design with a lead frame surrounded by molding members, incorporating a heat conductive pad and fluorescent material to enhance heat dissipation and light extraction, where the heat conductive pad and lead frame efficiently discharge heat, and the fluorescent material increases light extraction efficiency by converting light emitted from the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of light-emitting devices is reduced, then device integration and miniaturization are improved, but light extraction efficiency and heat resistance deteriorate
Solution Approach 1:
The patent applies local quality by creating a reflective structure specifically at the side surfaces and bottom surface of the light-emitting device package. The molding member includes a reflective layer or reflective structure formed on its inner surface, which locally enhances light extraction efficiency without requiring the entire device to be larger. This localized reflective structure redirects light that would otherwise be trapped, improving light extraction in the miniaturized device configuration.
Solution Approach 2:
The patent addresses light extraction in miniaturized devices by utilizing the dimensional space created by the package structure itself. The molding member forms a three-dimensional encapsulation around the light-emitting device, with reflective surfaces positioned at multiple orientations (side surfaces and bottom surface). This dimensional approach allows light to be extracted and redirected through various spatial paths, compensating for the reduced device size and maintaining high light extraction efficiency.
2Volume of moving object
If the size of light-emitting devices is reduced, then device integration is improved, but heat dissipation capability deteriorates
Solution Approach 1:
The patent introduces a heat conductive pad as an intermediary thermal management component. This pad is positioned between the light-emitting device and the molding member, serving as a thermal interface that facilitates heat transfer from the device to the surrounding structure. The heat conductive pad has higher thermal conductivity than the molding member material, creating an efficient thermal pathway that enables effective heat dissipation in the miniaturized device configuration.
Solution Approach 2:
The molding member serves multiple functions simultaneously: it provides mechanical encapsulation and protection of the light-emitting device, acts as a structural support, and through its integrated heat conductive pad, functions as a thermal management component. This multi-functionality allows the compact device structure to maintain effective heat dissipation capabilities without requiring separate dedicated cooling systems that would increase device size.
3Ease of manufacture
If conventional molding members are used without reflective structures, then manufacturing simplicity is maintained, but light extraction efficiency deteriorates
Solution Approach 1:
The patent merges the molding member and reflective structure into a single integrated component. The reflective layer or reflective structure is formed as part of the molding member itself, either by incorporating reflective particles into the molding material or by forming a reflective coating on the inner surface of the molded cavity. This integration eliminates the need for separate reflective components and assembly steps, maintaining manufacturing simplicity while significantly improving light extraction efficiency through the added reflective functionality.
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 design effectively enhances both light extraction efficiency and heat resistance, leading to improved reliability and economic feasibility of the light-emitting device packages by stabilizing the light-emitting device and efficiently managing heat, thereby increasing product reliability and reducing defects.
Implementation Method 1
a heat conductive pad between a lower surface of the light-emitting device and an upper surface of the package substrate
Implementation Method 2
a fluorescent material on the upper surface of the light-emitting device
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Light-emitting device packages (10) include a package substrate (LF) surrounded by a lower molding member (MB), a light-emitting device (100) on the package substrate (LF) and surrounded by an upper molding member (MT), a heat conductive pad (100T) between a lower surface of the light-emitting device (100) and an upper surface of the package substrate (LF), a first electrode (100A) on an upper surface of the light-emitting device (100), a second electrode (100B) on the upper surface of the light-emitting device (100), a fluorescent material (100P) on the upper surface of the light-emitting device (100), and a plurality of bonding wires (BW) electrically connecting the package substrate (LF) with separate, respective electrodes of the first electrode (100A) and the second electrode (100B).