Blue Laser Copper Welding for Stable Spatter-Free Foil Joints
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Solution Overview
Problem
Laser welding of copper is challenging due to its high reflectivity, thermal conductivity, and heat capacity, leading to issues such as micro-explosions, spatter, and unpredictable weld quality, particularly in high-performance electronics and automotive applications, where better weld quality, speed, reproducibility, and reliability are needed.
Innovation Solution
A blue laser welding system with a wavelength of 450 nm, delivering at least 500 Watts of power, a beam parameter product of 44 mm mrad or less, and a spot size of 400 μm or less, combined with a non-oxidizing clearing gas to prevent oxidation and splatter, allowing for stable conduction or keyhole mode welding with high absorption rates and minimal porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IR laser welding is used on copper, then welding capability is achieved, but micro-explosions and spatter occur due to rapid vaporization
Solution Approach 1:
The patent changes the laser wavelength parameter from infrared (1030 nm) to blue (450 nm) to fundamentally alter the interaction with copper. This parameter change enables conduction mode welding without keyhole formation, eliminating the rapid vaporization that causes micro-explosions and spatter while maintaining reliable weld quality.
Solution Approach 2:
The patent employs periodic modulation of laser power to maintain stable welding conditions. By cycling the power delivery, the system prevents runaway heating and vaporization, thereby avoiding micro-explosions while sustaining the welding process and producing consistent weld quality.
2Length of stationary object
If high-power IR laser is used to initiate keyhole weld, then welding depth is improved, but process control becomes difficult and defects increase
Solution Approach 1:
The patent changes the laser wavelength from infrared to blue and operates in conduction mode rather than keyhole mode. This parameter change achieves sufficient penetration depth through controlled heat conduction into the copper, avoiding the instability and defects associated with keyhole formation while maintaining manufacturing precision.
Solution Approach 2:
The patent implements feedback control through periodic laser power modulation and process monitoring. This feedback mechanism maintains stable welding conditions, ensuring consistent weld penetration depth and quality while preventing the runaway effects that lead to defects in uncontrolled keyhole welding.
3Strength
If ultrasonic welding is used for copper foils, then bonding is achieved, but sonotrode wear causes process variability
Solution Approach 1:
The patent replaces the mechanical ultrasonic welding system with a blue laser welding system. This substitution eliminates the mechanical sonotrode that wears during production, thereby removing the source of process variability while maintaining strong bond strength through laser-induced metallurgical bonding.
Solution Approach 2:
The patent transitions from mechanical vibration-based welding to laser-based thermal welding. This parameter change from mechanical to optical/thermal energy delivery eliminates contact wear issues while achieving reliable bond strength and improved process reproducibility through non-contact welding.
4Use of energy by moving object
If blue laser with high power density is used, then absorption rate increases, but oxidation and splatter may occur
Solution Approach 1:
The patent introduces a shielding gas environment (typically argon or nitrogen) to protect the copper from oxidation during blue laser welding. This inert atmosphere prevents oxygen from reacting with the molten copper while allowing the high absorption rate to proceed, thereby eliminating oxidation and splatter hazards.
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 enables high-quality, spatter-free welds with consistent microstructure and hardness matching the base material, achieving deep penetration and reliable bonding of copper foils and thicker copper or aluminum parts with improved speed and reproducibility.
Implementation Method 1
Laser welding of copper has proven to be very challenging due to high reflectivity... When using an IR laser source at 1030 nm, the high reflectivity of the copper at this wavelength makes it difficult to couple power into the material to heat and weld it
Implementation Method 2
Laser welding of copper with current infrared lasers method and systems is challenging, and has problems, due to the high reflectivity, high thermal conductivity, low vaporization points and high heat capacity
Data Source
AI summary
A visible light laser system and operation for welding materials together. A blue laser system that forms essentially perfect welds for copper based materials. A blue laser system and operation for welding conductive elements, and in particular thin conductive elements, together for use in energy storage devices, such as battery packs.