LED Leadframe Trench and Through-Hole for Stress Reduction
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Solution Overview
Problem
Existing light-emitting device manufacturing methods face challenges in achieving strong adhesion between resin and leads, stress distribution during cutting, and protection against environmental degradation, particularly due to sulfur ingress.
Innovation Solution
The design incorporates a through-hole continuous with a trench in the lead's main body portion, which enhances resin adhesion and stress absorption, and uses a transparent resin portion with light-scattering particles to protect the light-emitting element and improve color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a resin-molded leadframe is prepared with leads linked by link portions, then multiple light-emitting devices can be manufactured, but stress concentration occurs during cutting of the link portions
Solution Approach 1:
The lead structure is segmented into main body portions and extension portions connected by link portions. The through-holes are strategically positioned in the link portions to segment the stress distribution path, preventing stress concentration at single points during cutting operations.
Solution Approach 2:
Different regions of the lead are given different properties: the main body portions maintain structural integrity, while the link portions contain through-holes to specifically address stress concentration issues during cutting, creating local quality variations that optimize both manufacturing and strength.
2Ease of manufacture
If the lead structure is simplified for easy manufacturing, then production cost decreases, but adhesion between resin and lead deteriorates
Solution Approach 1:
The lead structure incorporates through-holes that create a porous configuration in specific regions. This porous structure increases the surface area and mechanical interlocking between the resin and lead, significantly improving adhesion strength while maintaining manufacturing simplicity through standard molding processes.
3Ease of operation
If leads are exposed to environment, then electrical connectivity is maintained, but sulfur ingress causes degradation
Solution Approach 1:
The resin molded body acts as a protective shell that encapsulates the leads, preventing sulfur ingress while maintaining electrical connectivity. The extension portions provide necessary electrical connections to external circuits while the resin shell provides environmental protection against harmful factors like sulfur.
4Device complexity
If standard lead configuration is used, then manufacturing process is simple, but stress distribution during cutting is poor
Solution Approach 1:
The through-holes are pre-formed in the lead structure before the cutting process. This preliminary action creates predetermined stress distribution paths that guide and分散 stress during subsequent cutting operations, preventing stress concentration and improving overall stress distribution without requiring complex post-processing.
Data Source
AI summary
A light-emitting device includes a package and a light-emitting element. The package includes a pair of leads each including a main body portion and an extension portion, a resin portion holding the pair of leads, and a concave portion having a bottom surface where an upper surface of each of the pair of leads is exposed. The extension portion extends from an outer edge of the main body portion to an outer surface of the package. The light-emitting element is mounted at the bottom surface of the concave portion. The main body portion has a trench and a through-hole in a portion of the main body portion buried in a sidewall of the concave portion. The through-hole is continuous with the trench. When viewed in top-view, the through-hole is provided inward of the outer edge of the main body portion at a vicinity of the extension portion.