LED Package Alignment via Asymmetric Lead-Pad Matching
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Solution Overview
Problem
Existing light emitting diode (LED) packaging technologies face challenges in maintaining proper alignment and preventing tilt during assembly, leading to issues with light emission efficiency and reliability.
Innovation Solution
A light emitting apparatus design featuring a light emitting device with external leads that match the shape and size of electrode pads on a flexible board, along with a stiffener, ensures secure electrical connection and prevents tilt, using surface mount technology (SMT) and a light guide plate to enhance light distribution and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light emitting device is mounted on a board using conventional packaging technology, then the assembly process is simple, but the light emitting device tilts and misalignment occurs
Solution Approach 1:
The packaging structure is divided into separate functional components: a rigid support structure for positional stability, a flexible circuit board for electrical connection, and a light-emitting component module. This segmentation allows each part to optimize its function while maintaining precise alignment through the modular assembly approach.
Solution Approach 2:
The patent introduces a vertical stacking dimension by placing the light emitting device upright on the board rather than flat mounting. The rigid support structure extends vertically to provide mechanical stability, while the flexible circuit board makes electrical connections at the base, resolving alignment issues by separating mechanical support and electrical connection functions into different spatial dimensions.
2Reliability
If the lead electrode shape does not match the pad shape, then the manufacturing process is simpler, but electrical connectivity and alignment are poor
Solution Approach 1:
The lead electrodes are designed with asymmetric shapes that precisely complement the asymmetric pad layouts on the flexible circuit board. This asymmetric matching ensures optimal electrical connectivity and mechanical alignment, with each lead electrode's shape tailored to its specific pad's geometry rather than using uniform standardized connectors.
Solution Approach 2:
The lead electrode shapes are designed as precise geometric copies or inverses of the pad shapes, ensuring perfect mating and alignment. This copying approach guarantees reliable electrical connectivity by making the electrical interface geometry identical between corresponding male and female connection elements.
3Reliability
If a rigid board is used for mounting, then structural stability is good, but light leakage increases and heat dissipation is reduced
Solution Approach 1:
The patent replaces the conventional rigid board with a flexible circuit board that has inherent light-shielding properties. The flexible substrate acts as a light trap, preventing light leakage from the edges while maintaining structural stability through its flexible-rigid composite construction. This flexible film approach also improves heat dissipation by allowing thermal management structures to conform closely to the light emitting device.
Solution Approach 2:
The flexible circuit board is designed to provide uniform mechanical support and thermal conduction across the mounting area, creating equipotential conditions for both structural stability and heat dissipation. The board's flexible nature allows it to conform to thermal expansion differences while maintaining consistent electrical and thermal pathways.
Data Source
AI summary
Provided are a light emitting apparatus and a light unit having the same. The light emitting apparatus includes a light emitting device includes a light emitting element and a plurality of external leads, and a plurality of electrode pads under the light emitting device.