Modular LED Illumination with Segmented Lead Frames
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Solution Overview
Problem
The existing methods for mounting light emitting diodes (LEDs) on lead frames result in a low yield rate and increased costs due to the need for multiple soldering spots and the risk of defective LEDs causing the entire array to be discarded if one is faulty.
Innovation Solution
A modular illuminating apparatus is created using LEDs, lead frames, and a transparent sealer, where LEDs are mounted on lead frames, tested, and sealed, allowing for easy replacement of defective LEDs, reducing the number of mounting spots and increasing yield rates through a method that includes a testing step and additional spare lead frames for re-mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light emitting diodes are packaged and mounted on a printed circuit board, then the mounting cost increases due to multiple soldering spots, but the yield rate improves because each package can be tested independently before final assembly
Solution Approach 1:
The patent divides the LED array into multiple independent packages, where each package contains a subset of LEDs connected in series. This segmentation allows independent testing and replacement of individual packages, improving yield rate while reducing the number of soldering spots needed for final assembly compared to mounting each LED individually on a PCB.
Solution Approach 2:
The patent performs preliminary assembly of LED arrays on lead frames before final mounting. Multiple LEDs are connected in series on the lead frame and tested as a complete unit, allowing defective arrays to be identified and replaced as a single component, thereby reducing the number of soldering operations and improving manufacturing efficiency.
2Ease of manufacture
If light emitting diodes are mounted on a series of lead frames, then the mounting cost reduces due to fewer soldering spots, but the yield rate decreases because all LEDs are discarded if one is defective
Solution Approach 1:
The patent segments the LED array into multiple independent packages mounted on the lead frame. Each package contains a specific number of LEDs connected in series and can be independently tested and replaced. This segmentation maintains the cost advantage of lead frame mounting while improving yield rate by isolating defects to individual packages rather than the entire array.
Solution Approach 2:
The patent applies different functional characteristics to different parts of the lead frame structure. Specific areas are designated for mounting LED packages, while other areas serve as connection points or spares. This local differentiation allows for targeted replacement of defective packages without affecting the entire array, improving yield rate while maintaining manufacturing efficiency.
3Reliability
If spare lead frames are included for re-mounting defective LEDs, then the yield rate increases through replacement capability, but the device complexity increases due to additional components
Solution Approach 1:
The patent incorporates spare LED packages as integral parts of the lead frame assembly. These spare packages are positioned and connected in the same manner as functional packages, allowing direct replacement without additional wiring or structural modifications. This approach increases yield rate through replacement capability while minimizing the increase in device complexity.
Solution Approach 2:
The lead frame structure is designed to serve multiple functions: mounting functional LED packages, providing electrical connections, and housing spare replacement packages. The same structural elements and connection methods are used for both functional and spare packages, reducing overall complexity while enabling yield improvement through replacement.
Data Source
AI summary
An illuminating apparatus has a reduced number of mounting spots by soldering or the like to permit an increased yield rate and a reduced cost. The illuminating apparatus has light emitting diodes, lead frames, and a transparent sealer. N light emitting diodes, N sets of lead frames mounted with the N light emitting diodes, and one set or more of lead frames each not mounted with a light emitting diode are sealed by the transparent sealer for integration into a modular illuminating apparatus. Also provided are a method for fabricating the illuminating apparatus, and a display apparatus using the illuminating apparatus.