Laser Welding Structure With Holed Overlap for Stronger Low-Resistance Joints

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Solution Overview

Problem

Existing welding methods face challenges in achieving high bonding strength and low electric resistance, particularly in laser welding techniques where the interface between metal members is irradiated with a laser beam.

Innovation Solution

A welding method involving a first metal member with a pre-formed hole superimposed on a second metal member, where the laser beam is applied in a spiral trajectory to create a melted interface with a eutectic portion, enhancing bonding strength and reducing electric resistance by forming a protruding interface and overlap portion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a laser beam is applied to weld a first metal member and a second metal member, then the welding process is simple and fast, but the bonding strength is insufficient and electric resistance is high

Engineering Contradiction:
Improvewelding speedVSAvoidbonding strength
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

A hole is formed in the first metal member before the welding process. This preliminary action creates a specific structure that guides the laser beam and promotes better metal fusion, resulting in improved bonding strength while maintaining the simplicity and speed of laser welding.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If a laser beam is applied to weld a first metal member and a second metal member, then the welding process is simple and fast, but the electric resistance is high

Engineering Contradiction:
Improvewelding speedVSAvoidelectric resistance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

A hole is formed in the first metal member before welding. This preliminary structure enables better electrical contact and lower resistance at the interface, while the welding process remains simple and fast using a laser beam.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If the laser beam is applied to melt the metal members, then welding is achieved, but the interface structure is insufficient for optimal bonding

Engineering Contradiction:
Improvewelding process simplicityVSAvoidinterface structure quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A hole is formed in the first metal member before the welding process. This preliminary action creates an optimized interface structure that enhances bonding quality while maintaining the simplicity of the laser welding process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The hole creates a localized structure at the welding interface that improves metal fusion and bonding characteristics. This local structural modification enhances the overall interface quality without complicating the global welding process.

Inventive Principle:
Principle #3Local quality

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

The method significantly improves bonding strength by 26% and reduces electric resistance by 34%, as demonstrated in the examples, by creating a robust interface and increasing the bonded area between the metal members.

Implementation Method 1

an interface between the two members is irradiated with laser light

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

the first metal member and the second metal member are melted by irradiation of the laser beam to form a liquid phase portion

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP3733339B1Welding structure, wiring board with metal piece
Publication Date: 2024.02.07 FUJIKURA LTD
  • EP3733339B1 patent drawingFigure 1A~1C
  • EP3733339B1 patent drawingFigure 1D
  • EP3733339B1 patent drawingFigure 2

AI summary

The welding structure includes a first metal member and a second metal member that are superimposed and welded together. The first metal member has a hole, and the second metal member has a nugget portion that is solidified again after being melted by heat of laser light. In which a peripheral portion of the hole in the first metal member covers the nugget portion, and a part of the nugget portion is exposed through the hole.