Light-emitting Device Lead Segmentation for Flux Corrosion
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Solution Overview
Problem
The existing light-emitting devices face reliability issues due to flux entering the device through interfaces between the resin portion and leads, which can lead to corrosion and affect the electrical connection of the protection element.
Innovation Solution
A light-emitting device design featuring a resin package with a recessed portion, where the first and second leads have metal layers on their top surfaces and are integrated with a resin portion, including a stepped portion that extends the path for flux to reduce its reach to the protection element, thereby discouraging corrosion and maintaining a reliable electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the resin package includes interfaces between resin portion and leads, then the structure allows for integration of components, but flux can enter the device from outside via these interfaces, reducing reliability
Solution Approach 1:
The lead structure is segmented into multiple portions (first lateral portion, second lateral portion, third lateral portion) with different exposure configurations. The second lateral portion is exposed on the lateral surface while the first and third lateral portions are covered by the resin portion, creating segmented protection zones that block flux entry paths while maintaining manufacturing integration.
Solution Approach 2:
The resin portion acts as an intermediary protective barrier between the external environment (flux) and the internal components (protection element, light-emitting element). The resin portion strategically covers specific lead portions to mediate protection without completely exposing any lead surfaces, thereby blocking flux entry while maintaining electrical functionality.
2Reliability
If leads are fully exposed for electrical connection, then electrical connectivity is ensured, but flux can reach the protection element and cause corrosion
Solution Approach 1:
Different portions of the lead structure have different exposure qualities: the second lateral portion is exposed on the lateral surface for electrical connection, while the first and third lateral portions are covered by the resin portion for protection. This local differentiation ensures electrical connectivity where needed while providing corrosion protection where harmful factors are present.
Solution Approach 2:
The protection strategy extends into the spatial dimension by utilizing the lateral surface exposure of the second lateral portion for electrical connections while the resin portion covers other lateral portions from the bottom surface and side entry paths, creating a multi-dimensional protection architecture that blocks flux from reaching the protection element.
Data Source
AI summary
A light-emitting device includes: a resin package including: a first lead, a second lead, and a resin portion, wherein each of the first lead and the second lead has a top surface and a bottom surface and comprises a metal layer formed at least at the top surfaces; a light-emitting element electrically connected to the first lead and the second lead; and a protection element located on a first surface portion of the top surface of the first lead. The first lead includes: a first lateral portion and at least one second lateral portion. A second surface portion is formed at the top surface of the first lead between the protection element and at least one of the first lateral portion and the at least one second lateral portion, the second surface portion being embedded in the resin portion and extending in a height direction.