Light Emitting Device Package With Stepped Wall Thickness
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Solution Overview
Problem
Compact light emitting devices face challenges with low package strength, leading to bending or chipping, and issues like 'short shot' during molding, which affect yield and quality.
Innovation Solution
A light emitting device design featuring a package with protruding lead frames accommodated in a concave portion, and walls structured with a stepped thickness to enhance mechanical strength and prevent deformation, while minimizing size and mounting space, and using a translucent covering material to prevent material leakage during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the package is made thinner to achieve compact size, then the device becomes more compact and lightweight, but the package strength decreases causing bending or chipping
Solution Approach 1:
The package wall thickness is made non-uniform, with thicker portions positioned strategically at locations requiring enhanced strength (such as near lead frame mounting areas and corners), while other areas maintain thinner walls to preserve compactness. This local variation in thickness allows the package to achieve both compact size and adequate strength without uniform thickening throughout.
2Area of stationary object
If the package wall is made thinner to reduce device size, then mounting space is minimized, but the package becomes more susceptible to deformation during handling
Solution Approach 1:
Strategic thickening of package walls at specific locations (such as near lead frame mounting areas and corners) provides localized reinforcement that prevents deformation during handling, while maintaining thin walls in other areas to minimize overall mounting space and preserve device compactness.
3Ease of manufacture
If conventional molding methods are used, then manufacturing is simpler, but short shot occurs where molding material does not reach all corners
Solution Approach 1:
The package design incorporates pre-planned thick wall portions at strategic locations before the molding process begins. These pre-positioned thick sections act as material reservoirs that ensure adequate material flow and filling during conventional molding, preventing short shot defects without requiring complex molding process modifications.
4Length of stationary object
If the package is made thinner to achieve compact size, then device height is reduced, but yield decreases due to increased bending and chipping
Solution Approach 1:
The package employs variable wall thickness with strategic reinforcement zones positioned at locations prone to bending and chipping (such as corners and lead frame mounting areas). This allows the overall package height to remain compact while local thickening provides the necessary strength to prevent defects during handling and assembly, thereby maintaining high manufacturing yield.
Data Source
AI summary
A light emitting device comprises: a light emitting element; a plurality of lead frames to which the light emitting element is electrically connected; and a package that includes in its interior at least part of said lead frames which protrude outward at one end, that is equipped with an opening for taking off light from the light emitting element, and that extends in the lengthwise direction, wherein a concave portion is formed in the outer surface of at least part of the package wall, the lead frames protruding outward from the package are accommodated in this concave portion, and the walls that constitute said opening and are across from each other in the widthwise direction of the package comprise at least a first wall that is across from the light emitting element, a second wall that is raised up by a step from the first wall, and a third wall that links the first wall and the second wall, and the second wall and third wall are formed thicker than the first wall.