Multi-Pass Laser Welding for Deep Joints With Fewer Blowholes
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Solution Overview
Problem
Conventional laser welding methods face challenges in minimizing sputtering and blowholes, which affect the quality and strength of the weld, particularly in semiconductor module manufacturing, where achieving a balance between welding depth and strength is difficult.
Innovation Solution
The method involves scanning a laser at a predetermined speed and output to create a keyhole between base materials, with multiple passes over a common region to deepen the weld and enhance bonding strength, while maintaining a shallow welding depth to reduce sputtering and blowholes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If laser welding is performed with high output and slow scanning speed to increase welding depth, then welding depth is improved, but sputtering and blowholes increase
Solution Approach 1:
The welding process is divided into multiple passes (first welding pass and second welding pass) with different parameter settings. The first pass uses higher output and slower scanning speed to achieve sufficient welding depth, while the second pass uses lower output and faster scanning speed to eliminate sputtering and blowholes without significantly increasing total processing time.
Solution Approach 2:
The laser welding is performed in periodic cycles with alternating parameter sets. Each cycle consists of a deepening pass followed by a cleaning pass, creating a periodic pattern of parameter variation that systematically addresses both welding depth and defect reduction throughout the welding process.
2Productivity
If laser scanning speed is increased to improve productivity, then productivity is improved, but welding depth decreases and weld quality deteriorates
Solution Approach 1:
The welding process is divided into multiple passes (first welding pass and second welding pass) with different parameter settings. The first pass uses higher output and slower scanning speed to achieve sufficient welding depth, while the second pass uses lower output and faster scanning speed to eliminate sputtering and blowholes without significantly increasing total processing time.
Solution Approach 2:
The multi-pass welding approach maintains continuous productive action by performing multiple welding passes over the same region. Rather than idle waiting or rework, each pass contributes useful work - the first pass creates the weld, and the second pass refines it - ensuring continuous value addition throughout the process.
3Length of stationary object
If laser output is increased to deepen the weld, then welding depth is improved, but sputtering increases
Solution Approach 1:
The welding process is divided into multiple passes (first welding pass and second welding pass) with different parameter settings. The first pass uses higher output and slower scanning speed to achieve sufficient welding depth, while the second pass uses lower output and faster scanning speed to eliminate sputtering and blowholes without significantly increasing total processing time.
Solution Approach 2:
The invention systematically changes laser parameters (output and scanning speed) between different welding passes. The first pass operates with high output and low scanning speed for depth, while the second pass uses reduced output and increased scanning speed for quality, demonstrating controlled parameter variation to resolve the contradiction.
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 approach effectively reduces sputtering and blowholes, achieving a strong and uniform bond with improved tensile shear strength and bonded area, even with faster scanning speeds that might otherwise degrade weld quality.
Implementation Method 1
a laser beam is applied on a lamination member 3 including a first base material 1 and a second base material 2 provided on the first base material 1
Implementation Method 2
both the first base material 1 and the second base material 2 are melted
Implementation Method 3
a keyhole is formed by vaporization of both the first base material 1 and the second base material 2
Implementation Method 4
a keyhole is formed by vaporization of both the first base material 1 and the second base material 2
Data Source
AI summary
Provide is a laser welding method of a lamination member including a second base material provided on a first base material, the laser welding method including forming a first scanning route by scanning a laser from a first point of the lamination member to a second point different from the first point, the first point being predetermined, and forming a second scanning route, at least a portion of which is shared with the first scanning route, by scanning the laser from a third point of the lamination member to a fourth point different from the third point, the third point being predetermined, and melting the first base material and the second base material in a common region between the first scanning route and the second scanning route, in which a welding depth of the first base material is 0.2 mm or more and 0.7 mm or less.