Laser welding copper is difficult mainly because copper has high thermal conductivity and high reflectivity. Heat spreads quickly, making it hard to maintain thermal balance. Reflection also leaves too little effective energy input.
High thermal conductivity causes rapid heat diffusion
Copper's thermal conductivity is much higher than common materials such as steel and aluminum. When the laser beam hits the copper surface, heat from the high energy density spreads quickly from the weld joint to the surrounding area. The local temperature cannot rise to the melting point fast enough. Copper's melting point is 1083°C. This rapid heat diffusion makes it hard to maintain a stable thermal balance in the weld area. Molten pool formation is difficult, and "lack of fusion" or "incomplete penetration" can occur. In micro welding, copper's thermal conductivity further amplifies heat loss, making the process very unstable.
High reflectivity reduces laser energy absorption
Copper has very high reflectivity at common welding laser wavelengths, such as 1064 nm Nd:YAG laser or 1070 nm fiber laser. Initial reflectivity can reach over 90%. Most laser energy is reflected directly and cannot be converted into heat for melting the material. Even when some energy is absorbed, copper's thermal conductivity quickly conducts it away. The actual energy density used to melt copper is insufficient. This combined reflection and conduction effect means welding needs higher energy input to achieve a reliable connection.
Maintaining thermal balance is difficult
Laser welding relies on local high temperature to melt material and form a molten pool. Copper's high thermal conductivity disrupts this process. When the laser beam moves, the already heated area cools quickly through conduction. The temperature at the front of the molten pool is insufficient, so a continuous weld cannot form. Copper also has poor liquid fluidity. When the molten pool solidifies, it easily produces porosity, cracks, and other defects, further increasing welding difficulty.
To address copper welding challenges, the industry commonly uses these methods:
Increase laser power: raise laser output power from the usual 1 to 2 kW to 4 to 6 kW. This compensates for reflection and conduction losses and ensures enough energy reaches the welding interface.
Optimize wavelength selection: use green laser at 532 nm or blue laser at 450 nm. These wavelengths have higher absorption in copper. Blue laser absorption can be more than twice that of green laser, greatly reducing reflection loss.
Pulsed laser mode: use pulsed laser instead of continuous laser. Short high-energy pulses heat the material quickly, reduce heat diffusion time, and lower the heat-affected zone.
Auxiliary process support:
Preheating: preheat copper locally or fully to reduce the gap between initial temperature and melting point, lowering energy demand.
Filler material: use copper-based filler wire containing phosphorus, nickel, and other elements. Alloying lowers the melting point and improves fluidity.
Shielding gas optimization: use an argon and helium mixture to reduce oxidation and porosity during welding.
We can machine custom nozzles, fixtures, protective lens holders, and other precision parts for laser welding machines from customer drawings, for single-piece or low-volume production.
Despite the difficulty, laser welding still has advantages for copper:
Non-contact processing avoids mechanical stress and suits precision micro welding.
Weld width is small, controllable within 0.1 mm. The heat-affected zone is small, and deformation is low.
Welding speed is fast, reaching several meters per minute. Efficiency is far higher than traditional TIG welding.
Weld surface is smooth and needs no later grinding, making it suitable for automated production lines.
As blue laser, hybrid laser, and other technologies mature, copper laser welding yield has improved clearly. It is widely used in new energy vehicle battery connections, 5G communication devices, and other fields.
Our custom precision component machining capability is not limited to laser welding equipment. Beyond welding nozzles, fixtures, and protective lens holders, we also machine yacht precision components, RC car structural parts, medical device parts, and non-standard parts for food machinery, textile machinery, and tobacco packaging machinery. Hansheng Automation works from customer drawings and production quantities to deliver single-piece or low-volume precision machining.
