Light-emitting Device Curved Lead Frame Resin Cracking
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Solution Overview
Problem
Light-emitting devices with pressed lead frames can experience cracking in the resin portion due to sharp corners, leading to potential strength issues and inefficient light reflection.
Innovation Solution
A light-emitting device design featuring a resin package with curved portions on the leads that are buried in the resin, reducing the likelihood of cracking and enhancing adhesion and light reflection by eliminating sharp corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pressing process is applied to the lead frame to reduce friction during cutting, then ease of manufacture is improved, but corner portions may form sharp edges that cause cracking in the resin portion
Solution Approach 1:
The patent applies curvature to the corner portions of the lead frame by forming rounded corners instead of sharp edges. This is achieved through a pressing process that creates a curved surface at the corner portions, which eliminates stress concentration points and prevents resin cracking while maintaining the pressing benefits for cutting ease.
Solution Approach 2:
The patent changes the geometric parameters of the lead frame corner portions by controlling the pressing process to create specific curvature radii. The corner portions are pressed to form a curved surface with a controlled radius of curvature, transforming the sharp corner geometry into a rounded geometry that prevents resin cracking.
2Ease of manufacture
If corner portions are formed on pressed leads to facilitate cutting, then ease of manufacture is improved, but cracks are generated in the resin portion near the corner portions
Solution Approach 1:
The patent applies curvature to the corner portions of the lead frame by forming rounded corners instead of sharp edges. This is achieved through a pressing process that creates a curved surface at the corner portions, which eliminates stress concentration points and prevents resin cracking while maintaining the pressing benefits for cutting ease.
Solution Approach 2:
The patent changes the geometric parameters of the lead frame corner portions by controlling the pressing process to create specific curvature radii. The corner portions are pressed to form a curved surface with a controlled radius of curvature, transforming the sharp corner geometry into a rounded geometry that prevents resin cracking.
Data Source
AI summary
A light-emitting device includes: a resin package including: a lead part including a first lead and a second lead, each including a main body portion and a raised portion connected to the main body portion, wherein an upper surface of each of the first lead and the second lead includes a first primary surface portion in the main body portion and a curved portion in the raised portion in a cross-sectional view taken in a direction perpendicular to an upper surface of the lead part, and wherein the curved portion is continuous with and curved upward from an end portion of the first primary surface portion, a resin portion, and a recess defined by a portion of the upper surface of the lead part and the resin portion; and a light-emitting element mounted in the resin package. The curved portion is buried in the resin portion.