Lead Frame Bending for LED Package Integrity

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Solution Overview

Problem

The compact size of side view type light emitting device packages limits the size and number of mountable devices, and the resin material is prone to thermal degradation due to heat and light exposure, with the lead frame bending causing potential damage to the package body.

Innovation Solution

The lead frame is extended outward and bent to be level with the package body's surface, and light emitting devices are aligned on the longitudinal center axis to enhance luminance uniformity and prevent damage during bending, while an electrostatic discharge device is used to protect the devices from external shocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the lead frame is bent toward the outer surface of the package body, then the lead frame can be mounted and connected, but the package body may be damaged due to the bending force

Engineering Contradiction:
Improvelead frame mountingVSAvoidpackage body integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The lead frame is extended beyond the outer surface of the package body before bending, creating a buffer zone that allows the bending force to be applied away from the body. This preliminary extension prevents direct transmission of bending stress to the package body, thereby enabling lead frame mounting while maintaining body integrity.

Inventive Principle:
Principle #10Preliminary action

2Volume of moving object

If the package body is reduced in size to achieve a compact design, then the overall package becomes smaller and slimmer, but the lead frame size and thickness are limited which may cause damage during bending

Engineering Contradiction:
Improvepackage sizeVSAvoidlead frame bending resistance
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The lead frame is extended in the longitudinal direction beyond the outer surface of the package body, utilizing the length dimension to provide additional bending margin. This dimensional extension allows the lead frame to accommodate bending forces without requiring increased thickness, thus maintaining compact package size while improving bending resistance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If light emitting devices are disposed off-center in the package body, then the packaging process is simplified, but the luminance uniformity of emitted light is reduced

Engineering Contradiction:
Improvepackaging processVSAvoidluminance uniformity
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent specifies that light emitting devices should be disposed symmetrically on the longitudinal center axis of the package body. This asymmetric positioning requirement (relative to off-center placement) ensures that light is emitted uniformly from the center, improving luminance uniformity while still allowing for simplified packaging processes through standardized mounting locations.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP2402993B1Lead frame used in a light emitting device package
Publication Date: 2019.09.18 LG INNOTEK CO LTD
  • EP2402993B1 patent drawingFigure 1
  • EP2402993B1 patent drawingFigure 2~3
  • EP2402993B1 patent drawingFigure 4~5

AI summary

A light emitting device package is provided comprising a light emitting device (30,40,50) including at least one light emitting diode and a body (10) including a first lead frame (92) on which the light emitting device is mounted and a second lead frame (91) spaced apart from the first lead frame, wherein at least one of the first and second lead frames is extending to a bending region (BD) in a first direction by a predetermined length on the basis of an outer surface of the body and is bent in a second direction intersecting the first direction.