Typical Laser Parameters for Welding Thin Copper Foils

Laser welding of thin copper foils is a refined process that requires precise control of laser parameters owing to copper's high reflectivity and thermal conductivity. This article details common laser settings used for welding copper foils typically ranging in thickness from about 50 to 500 micrometers.

Laser Wavelength and Laser Source

Traditional infrared lasers (around 1000 nm wavelength) have low absorption rates in copper (around 5-6%), making welding thin foils challenging. In contrast, blue diode lasers operating near 445-450 nm offer substantially higher absorption (~60-65%), enabling efficient energy coupling and melting of copper foils. Green lasers at approximately 515-532 nm are also effective, offering better absorption and heat input control than infrared lasers.

Laser Power

For welding thin copper foils, power levels typically range from 50 to 300 watts with blue diode lasers. Studies have shown using around 200 to 275 watts sufficient for welding foils up to 500 micrometers thick. The improved absorption with blue lasers means that lower power can achieve full penetration with less heat distortion.

Welding Speed

Welding speeds vary considerably depending on foil thickness and laser power but generally range between 1 mm/s and 100 mm/s. For example, stable keyhole and conduction welding of 0.2 mm thick copper was achieved at speeds from 1 mm/s to 5 mm/s with a 200-watt blue laser. Higher speeds of several hundred mm/min are also possible in optimized systems.

Beam Spot Size and Focus

Typical laser beam spot diameters for copper foil welding are from 50 to 200 micrometers, enabling a narrow heat-affected zone and reducing thermal damage. Maintaining precise focal position ensures a stable melt pool and consistent weld quality.

Laser Mode and Power Modulation

Continuous wave (CW) lasers are commonly used, but modulated or pulsed laser outputs can enhance weld quality by controlling heat input and minimizing defects. Fast modulation of blue laser power within milliseconds facilitates adaptation to surface condition variations, reducing oxide formation and spatter.

Shielding Gas

Inert gases like argon or nitrogen are used as shielding gases to prevent oxidation during welding, ensuring clean, smooth weld seams.

Summary of Typical Parameters

Advantages of Using Blue Diode Lasers

Blue lasers significantly improve process stability and weld quality when working with thin copper foils. Their higher absorption leads to better energy coupling and melting, which produces weld seams with excellent mechanical strength and electrical conductivity. Furthermore, blue lasers reduce heat distortion and heat-affected zones, yielding high surface quality with minimal spatter and oxide formation. These features are critical for electrical contacts, battery components, and thin sheet applications.

Conclusion

Laser welding of thin copper foils is best performed using blue diode or green lasers due to their superior absorption characteristics in copper. Optimizing key parameters like laser power (50-275 W), welding speed (1-100 mm/s), beam spot size (50-200 µm), and maintaining proper shielding gas allows for defect-free, high-quality welds with minimal heat damage. Continuous advancements in blue diode laser technology continue to expand the applications and reliability in welding copper foils, crucial for industries like electronics and battery manufacturing.

This concise guide provides a practical reference for engineers and technicians aiming to employ laser welding on thin copper materials with modern laser sources.