As a key material in the metal powder sector, copper and its alloys, with their exceptional electrical conductivity, thermal conductivity, and corrosion resistance, hold an irreplaceable position in high-end manufacturing fields such as aerospace, electronics, electric vehicles, and more. However, applying copper powder to Laser Powder Bed Fusion (LPBF), a mainstream metal additive manufacturing technology, has long faced a core challenge: the extremely low energy coupling efficiency between traditional infrared lasers and copper material. In recent years, with the maturation of green laser technology and the in-depth optimization of red laser solutions, domestic companies have introduced differentiated technological approaches based on these different wavelengths, offering the industry diverse solutions.
The difficulty in copper powder additive manufacturing stems from its material characteristics: high reflectivity and high thermal conductivity. For traditional near-infrared lasers with wavelengths around 1064nm, the reflectivity of solid copper exceeds 95%, meaning the vast majority of laser energy is directly reflected and cannot be effectively used for powder melting. Even if some energy is absorbed, copper's high thermal conductivity, reaching 390 W/(m·K) (approximately five times that of stainless steel), causes rapid heat dissipation, leading to an unstable melt pool and a high susceptibility to defects such as porosity, lack of fusion, and spatter. The core of solving this problem lies in utilizing the physical principle that copper's laser absorptivity varies with wavelength. Research shows that at room temperature, copper's absorptivity for 1064nm infrared laser is only 4%-5%, whereas for 515-532nm green light, it jumps to around 40%, an increase of nearly an order of magnitude. This significant difference in absorptivity stems from the distinct mechanisms of interaction between photons of different wavelengths and the free electrons in copper. Shorter wavelength (green) photons possess higher energy and are more readily absorbed by copper's electrons and converted into heat, fundamentally enhancing the utilization efficiency of laser energy.
Addressing Technical Challenges:
1. Low Absorptivity Issue: The inherently low absorptivity of copper for red laser light is a primary physical constraint. This is addressed through full-system high-reflection resistance design, involving deep customization from equipment architecture to process parameters to optimize energy transmission efficiency.
2. Narrow Process Window: Red laser printing of copper powder demands more precise process control. This is tackled by utilizing a self-developed GHA (Gas Atomization) powder manufacturing process to produce high-purity copper powder with a sphericity ≥95% and oxygen content <200 ppm, providing a material foundation for process optimization.
3. Thermal Management Challenge: Copper's high thermal conductivity causes rapid heat dissipation. Through "deep synergy" between the powder, equipment, and process, a breakthrough has been achieved in stabilizing thermal conductivity in the range of 400-410 W/(m·K), allowing the thermal performance of 3D-printed components to return to the ideal level typical of conventional pure copper.
Application Scenarios: The red laser solution is particularly well-suited for applications where cost sensitivity, large-format part batch production, and extremely high thermal conductivity requirements are paramount, such as data center liquid cooling plates, large-scale heat exchangers, and heat dissipation substrates for power electronics.