LED Substrate Conducting Portion Geometry for Soldering

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Solution Overview

Problem

Conventional LED units face issues with burr formation during singulation, leading to poor soldering adhesion and inadequate bonding strength between plastic packaging material and metallic die-bonding areas, resulting in reduced production yield and reliability due to poor soldering and moisture contamination.

Innovation Solution

The LED substrate structure features a conducting portion with oblique sides and an expansion region to facilitate easier soldering material flow, reducing burr length and improving soldering strength, while the interface layer with similar properties to the packaging material enhances bonding and prevents material leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the rear metal portion is made with triangular or cuplike shape to enhance fixing effect, then soldering ability is improved, but burr formation during singulation increases and creates long unsmooth segments that reduce soldering material adhesion

Engineering Contradiction:

Improvesoldering abilityVSAvoidsurface smoothness of metal portion

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The metal portion is divided into multiple segments along the cutting path, with each segment having optimized geometry. By segmenting the structure and positioning cutting lines strategically, the patent reduces the length of any single cutting segment, thereby minimizing burr formation while maintaining overall soldering effectiveness through the distributed segment structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the metal portion are given different geometric properties. The patent designs specific local areas with enhanced smoothness and optimized shapes that are specifically positioned to interact with soldering material, while other regions can tolerate more variation. This local optimization allows burr reduction in critical areas without compromising overall structural integrity.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If low temperature soldering process is used to reduce viscosity, then soldering material flowability is improved, but burr-related adhesion problems persist and production yield decreases

Engineering Contradiction:

Improvesoldering material flowabilityVSAvoidproduction yield

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent converts the harmful effect of burrs into a beneficial situation by designing the metal portion geometry such that burrs, when formed, are minimized in length and positioned in areas where they do not interfere with soldering material flow. The oblique side design causes burrs to form on shorter segments, transforming the inevitable burr formation into a less problematic condition that does not significantly impact production yield.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Adaptability or versatility

If packaging material is made of plastic and die-bonding area is made of metal, then material properties are optimized for各自 functions, but bonding strength at the interface is inadequate and allows moisture penetration

Engineering Contradiction:

Improvematerial functionalityVSAvoidbonding strength and moisture resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs composite material structure at the interface between packaging material and die-bonding area. By creating a composite construction that combines properties of both plastic and metal materials, the patent achieves adequate bonding strength while maintaining the functional advantages of each material. The composite structure prevents moisture penetration by eliminating the direct plastic-metal interface that causes reliability issues.

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design enhances soldering ability, reduces burr-related issues, and improves bonding strength, achieving 100% successful soldering in low-temperature processes and preventing moisture and soldering material intrusion into the packaging.

Implementation Method 1

The conducting portion has oblique sides to facilitate a soldering material climbing from a carrier board

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

The conducting portion has an expansion region adjacent to a first cutting segment formed along a bottom surface of the substrate

Methodology Applied

Scientific EffectGeometry optimization: Geometry

Data Source

PatentUS8803186B2LED substrate structure, LED unit and lighting module having the same

Publication Date: 2014.08.12 LITE ON TECH CORP

AI summary

An LED substrate structure has a substrate and a conducting portion. The substrate has a bottom surface and two opposite first lateral surfaces connected with the bottom surface. The bottom surface has the conducting portion formed thereon, and the conducting portion has a first cutting segment located on a contact border defined between one of the two first lateral surfaces and the bottom surface. The conducting portion further has an expansion region connected with the first cutting segment. The length of the first cutting segment is shorter than any segment taken on the expansion region parallel thereto.