Lead Frame Slots Enhance LED Package Coupling
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Solution Overview
Problem
Conventional light-emitting device packages face reliability issues due to property differences between metal lead frames and plastic molding materials, leading to unstable coupling and potential bending or widening, which affects light extraction efficiency and overall package reliability.
Innovation Solution
The design incorporates a lead frame with strategically formed slots that are filled by the molding structure, enhancing coupling reliability and light extraction efficiency by alleviating stress from property differences and improving the molding process's injection properties, while also using a reflective plating layer and a structured molding material with reflective powders to maximize light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal lead frames and plastic molding materials are directly coupled, then the package structure is simple, but the property differences cause unstable coupling and potential bending or widening
Solution Approach 1:
A buffer layer is introduced between the metal lead frame and plastic molding material to act as an intermediary that reduces the property differences between these two materials. This buffer layer prevents direct coupling issues while maintaining overall structural simplicity, resolving the contradiction between coupling stability and package structure complexity.
Solution Approach 2:
The package employs a composite material structure consisting of metal lead frame, buffer layer, and plastic molding material. This multi-material composite approach leverages the advantages of each material while mitigating their disadvantages, particularly using the buffer layer to harmonize the property differences between metal and plastic, thereby improving coupling stability without significantly increasing structural complexity.
2Ease of manufacture
If slots are formed in the lead frame, then the molding process injection properties improve, but the lead frame structure becomes more complex
Solution Approach 1:
The lead frame is segmented by forming slots that divide the continuous metal structure into separated regions. This segmentation improves molding injection properties by providing pathways for molten plastic to flow and distribute evenly, while the slots are designed to be minimal in number and strategic in placement to avoid excessive structural complexity.
3Reliability
If the molding structure fills all slots, then the coupling between lead frame and molding material is enhanced, but the light extraction efficiency may be reduced due to metal obstruction
Solution Approach 1:
The lead frame is designed with non-uniform slot distribution and varying slot dimensions at different locations. Areas where light extraction is critical have different slot characteristics compared to areas where coupling strength is prioritized. This local quality variation allows the structure to simultaneously achieve good coupling reliability and maintain light extraction efficiency by minimizing metal obstruction in critical optical paths.
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 improves the reliability and light extraction efficiency of the light-emitting device package by stabilizing the coupling between the lead frame and molding material, minimizing light loss, and enhancing the structural integrity and reflectivity of the package.
Implementation Method 1
enhancing coupling reliability and light extraction efficiency by alleviating stress from property differences
Implementation Method 2
using a reflective plating layer and a structured molding material with reflective powders to maximize light reflection
Data Source
AI summary
A light-emitting device package includes a lead frame, a light-emitting device chip, a molding structure, and a plurality of slots. The lead frame includes a first lead and a second lead including metal and spaced apart from each other. The light-emitting device chip is mounted on a first area of the lead frame, which includes a part of the first lead and a part of the second lead. The molding structure includes an outer barrier surrounding an outside of the lead frame and an inner barrier. The plurality of slots are formed in each of the first lead and the second lead. The inner barrier divides the lead from into the first area and a second area. The inner barrier fills between the first lead in the second lead. The second area is located outside of the first area. The plurality of slots are filled by the molding structure.