Light Emitting Device Lead Electrode Coating for Solder Bonding
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Solution Overview
Problem
Existing light emitting devices face issues with contamination and corrosion of lead electrodes due to solder components, which affect light absorption and electrical performance, and current solutions do not adequately address these problems.
Innovation Solution
A light emitting device design featuring a resin molded body with lead electrodes, where inward surfaces of the outer lead portions are covered by a light-transmissive coating film to reduce contamination and corrosion, while outward surfaces are exposed for solder bonding, facilitating reliable performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inward surface of the outer lead portion is exposed, then solder bonding is facilitated, but contamination and corrosion from solder components occur
Solution Approach 1:
The patent applies different surface treatments to different regions of the lead electrode. The inward surface is covered with a light-transmissive covering film to prevent contamination and corrosion, while the outward surface remains exposed to facilitate solder bonding. This local differentiation of surface properties resolves the contradiction between protection and bonding capability.
2Reliability
If the inward surface of the outer lead portion is covered by a light-transmissive covering film, then contamination and corrosion are reduced, but solder bonding becomes more difficult
Solution Approach 1:
The patent selectively applies the light-transmissive covering film only to the inward surface of the outer lead portion, leaving the outward surface exposed. This localized application ensures that the protective function is provided where needed while maintaining solder bonding capability on the outward surface.
3Ease of manufacture
If lead electrodes are exposed to solder components, then solder bonding is achieved, but light absorption and electrical performance deteriorate
Solution Approach 1:
The patent protects the inward surface of the outer lead portion with a light-transmissive covering film that prevents absorption of solder components, thereby maintaining light absorption and electrical performance. The outward surface remains exposed to enable solder bonding, thus resolving the contradiction between bonding and performance maintenance.
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 effectively reduces contamination and corrosion of lead electrodes, maintaining initial performance and reliability by preventing solder component absorption and discoloration, and enhancing solder bonding.
Implementation Method 1
the inward surface faces the first outer surface and is covered by a light-transmissive covering film
Data Source
AI summary
A light emitting device includes lead electrodes, and a housing including a resin molded body. The resin molded body has a first outer surface facing toward a first direction, a second outer surface facing toward a second direction perpendicular to the first direction, and a recess having an opening on the second outer surface and a bottom opposite to the opening in the second direction. Each of the lead electrodes includes an outer lead portion, and an inner lead portion to define the bottom of the recess. The outer lead portion is provided on the first outer surface and includes an inward surface and an outward surface opposite to the inward surface. The inward surface faces the first outer surface and is covered by a light-transmissive covering film. The outward surface is opposite to the inward surface in the first direction and is exposed from the light-transmissive covering film.