Light Emitting Device Package Lead-Frame Thin Regions
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Solution Overview
Problem
Conventional light emitting device packages face challenges in enhancing stress tolerance near the gap region between lead-frames, leading to issues such as molded resin cracking and lead-frame delamination, which affect the reliability of the package.
Innovation Solution
The design incorporates two lead-frames lined up in the lengthwise direction with molded resin formed as a single unit, featuring thin regions and extensions that are positioned opposite each other, increasing package strength and suppressing delamination by embedding these extensions within the molded resin and using recesses to enhance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lead-frames are molded as a single unit resin package with a cavity, then manufacturing efficiency is improved, but stress tolerance near the gap region deteriorates leading to molded resin cracking and lead-frame delamination
Solution Approach 1:
The patent applies local quality by creating thin regions at specific locations of the lead-frames where stress concentration occurs near the gap region. These thin regions are formed by removing material selectively at stress-prone areas while maintaining the overall single-unit molded structure, thereby improving stress tolerance without sacrificing manufacturing efficiency
Solution Approach 2:
The patent segments the lead-frame structure by dividing it into multiple regions with different thicknesses - thin regions at stress concentration points and thicker regions elsewhere. This segmentation allows the package to withstand stress better while maintaining the integrated molded construction for efficient manufacturing
2Reliability
If lead-frames are thinned by establishing recesses, then stress tolerance is improved, but structural strength deteriorates
Solution Approach 1:
The thin regions are created only at specific locations where stress concentration occurs near the gap region, rather than thinning the entire lead-frame. This localized approach improves stress tolerance while preserving structural strength in other critical areas of the lead-frame
Solution Approach 2:
The patent applies partial action by removing material only to the extent necessary at specific thin regions to relieve stress concentration, rather than uniformly thinning the entire lead-frame structure. This partial material removal achieves stress tolerance improvement without excessive loss of structural strength
Data Source
AI summary
The light emitting device package has a lengthwise direction as viewed from above and a lateral or widthwise direction perpendicular to the lengthwise direction, and is provided with two lead-frames lined-up in the lengthwise direction and molded resin formed as a single unit with the two lead-frames. The package is characterized in that each of the two lead-frames has a first thin region that is thinned by establishing a recess in the lower surface and/or the upper surface of the lead-frame, and that recess is covered with molded resin. Further, each lead-frame has an extension that narrows as it extends towards the opposite lead-frame. Both extensions are entirely within first thin regions, and as viewed from above, at least parts of the opposing extensions are positioned opposite each other in the lateral direction.