Thin LED Package Structural Integrity via Segmented Lead Frame
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Solution Overview
Problem
Conventional thin/low profile LED packages face challenges with structural integrity during manufacture and use, experiencing deformation and separation of the package casing from the lead frame, and they often lack sufficient surface area for mounting multiple LEDs, leading to compromised image quality and compatibility issues with standard mechanical/electrical supports.
Innovation Solution
The development of thin/low profile emitter packages with a casing and integral lead frame, featuring robust connections through metal gaps, cuts, and through-holes, and a cavity design that increases the exposed surface area of the lead frame, allowing for improved adhesion and mounting of LEDs, while maintaining a compact profile and enhancing color emission uniformity across various viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the package profile is reduced to thin/low profile, then the package becomes more suitable for flat panel displays and compact applications, but the structural integrity is compromised leading to deformation and separation during manufacture and use
Solution Approach 1:
The lead frame is segmented into multiple sections with metal gaps, cuts, and through-holes that create interlocking regions between the lead frame and package casing. This segmentation allows the thin package to maintain structural integrity by creating multiple attachment points rather than relying on a continuous structure.
Solution Approach 2:
The lead frame is nested within the package casing with specific portions extending through the cavity to the exterior surface. This nested arrangement allows the lead frame to be securely held within the casing while maintaining the thin profile, as the interlocking features create a robust connection without requiring additional structural support.
2Area of stationary object
If the package size is reduced to accommodate thin profile requirements, then the package fits better in compact displays, but the surface area for mounting multiple LEDs is insufficient
Solution Approach 1:
The cavity design utilizes the vertical dimension by having the bottom of the cavity extend closer to the exterior surface, creating an angled or curved configuration that maximizes the exposed surface area of the lead frame within the constrained footprint. This allows multiple LEDs to be mounted on the exposed lead frame portions without increasing the package's horizontal footprint.
3Volume of stationary object
If conventional thin package designs are used, then the package achieves compact dimensions, but separation occurs between the package casing and lead frame during manufacture and use
Solution Approach 1:
The lead frame is pre-formed with metal gaps, cuts, and through-holes before being inserted into the package casing. These pre-formed features are designed to interlock with the casing during assembly, creating a robust connection that prevents separation during subsequent manufacturing processes like reflow soldering and during end-use conditions.
4Device complexity
If the package structure is simplified to reduce complexity, then manufacturing becomes easier, but the package lacks robustness and experiences deformation during reflow process
Solution Approach 1:
The lead frame has different structural characteristics in different regions: some portions are continuous for electrical connectivity, while other portions have metal gaps, cuts, and through-holes for structural interlocking. This local differentiation allows the package to maintain simplicity where needed while providing enhanced robustness in critical connection areas during the reflow process.
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 provides improved structural integrity and color emission uniformity at different viewing angles, enabling the packages to maintain robustness during manufacturing and use, while allowing for increased LED density and compatibility with standard supports, thus enhancing the performance and versatility of LED displays.
Implementation Method 1
The lead frame comprises features that cooperate with the casing to provide a robust connection between the lead frame and the casing
Implementation Method 2
The bottom of the cavity comprises a different shape than the top of the cavity, with the shape of the cavity bottom increasing the surface area of the exposed lead frame portions
Implementation Method 3
Light emitting diodes (LEDs) are solid state devices that convert electric energy to light, and generally comprise one or more active layers of semiconductor material sandwiched between oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active layer where they recombine to generate light
Data Source
AI summary
The present invention is directed to LED packages and LED displays utilizing thin/low profile LED packages with improved structural integrity, emission characteristics, and customizable attributes. In some embodiments the improved structural integrity is provided by various features in the lead frame that cooperate with the casing for a stronger package. Moreover, in some embodiments the improved emission characteristics are provided by cavity features such as shape and depth, which provide for increased surface bonding area for multiple LED chips and increased viewing angle, respectively. Some embodiments also provide for gradated packages having customizable top portions for applications using smaller packages, with bottom portions comprising dimensions compatible with customary mechanical/electrical supports.