Copper Welding with
Blue High-Power Diode Laser

450 nm wavelength and 1000 W laser power (CW) open up new possibilities for high-quality laser copper welding and the effective processing of gold and other non-ferrous metals in industrial series production.

Copper, Gold and Other Non-Ferrous Metals

With previously available industrial laser beam sources, it was only possible with increased effort to process non-ferrous metals such as copper satisfactorily in series production. The development of blue laser diodes opens up new possibilities because copper and gold in particular absorb the blue light spectrum seven to twenty times better than infrared radiation (see diagram).

Now a first high-power diode laser has been developed that considerably improves the laser material processing of non-ferrous metals. Especially thin foils and sheets can be processed much more effectively with the blue laser. But the blue LDM diode laser offers even more advantages.

In addition to the high absorption of blue light, which greatly simplifies the melting of copper, the use of the typical diode laser intensity profile also contributes to the optimum processing result. Furthermore, Laserline's proven diode laser technology allows a finely graduated regulation of the laser power within milliseconds and thus an optimal adaptation to the process requirements. The weld seams created during copper welding are extremely clean and very smooth – regardless of the surface quality of the material before the welding process. They have excellent electrical conductivity and only a few spatters on adjacent material areas. The material efficiency is also particularly high, as the blue laser does on the one hand not require any overlaps or material reinforcements in the seam area. On the other hand, liquid copper has a high gap bridging capacity when processing with blue laser radiation. The possibility of controlled heat conduction welding makes it possible for the first time to use copper as the upper joining component when welding different metals. Even copper powder and thin copper foils can be joined with other materials such as steel and aluminium. When welding foils, considerable results have already been achieved in butt and edge welding.

The total energy consumption required for welding copper has been mathematically reduced by 84 percent compared to infrared lasers, and by as much as 92 percent for gold. This is due to the fact that 1 kW is now sufficient for welding copper and 0.5 kW for welding gold instead of 10 kW.

For the user, the LDM platform provides a familiar and industrially proven system technology that can be used in conjunction with processing optics optimized for the wavelength. Otherwise, only a few modifications are necessary to integrate the laser into production. Only the sight protection windows of processing cells and protective goggles have to be replaced due to the changed wavelength range in order to meet the requirements of laser safety for the employees in the company.

High Performance Thanks to Laserline's Functional Principle

The development of a powerful blue diode laser bar with a wavelength of 450 nm for the first time enabled the construction of a directly blue high-power diode laser. The blue laser developed in this way is based on the proven Laserline LDM system technology. Single emitters currently have a laser power of only about 3 to 5 watts. Therefore Laserline also uses the specially designed diode bars with active cooling for the blue laser. Such a diode bar currently generates an output of about 50 watts. By using appropriate optical elements, it is possible to combine several diode bars into a stack, just as with infrared lasers. The output power of a diode stack can thus be scaled to 500 watts. For the 1 kW version of the blue high-power diode laser, two stacks are combined in one laser beam. This unique technology provides the flexibility, modularity and scalability already known from other laserline products.

Laser Welding of Copper

Laser welding of copper is revolutionized by the development of a new blue diode laser. The blue laser beam enables high-quality processing of copper and other non-ferrous metals in industrial processes.

Copper Welding – The Process

With the blue laser, controlled heat conduction welding of copper and other non-ferrous metals with low material thickness is possible for the first time. Material thicknesses of less than one millimeter are no longer a problem. Whereas thin foils were previously cut rather than joined with an infrared laser, the blue laser can now be used to process the material in a targeted and controlled manner. With the help of the blue laser beam, the desired material is melted along the joints. The liquefied materials flow into each other and form the weld seam when they cool down. This process results in particularly smooth seams that are of outstanding quality and therefore highly stable. Basically, the process is the same as with an infrared laser – apart from the wavelength used.

Excellent Results

Initial tests show that the structure of the surface has no influence on the welding process, especially when processing copper. No matter whether the copper has been finely brushed, oxidized or etched in advance – the positive properties of the seam are retained.

Copper Cladding

The initial tests show that with the blue laser, cladding with copper powder is also possible.

Copper Cladding – The Process

The blue laser was also able to convince in the first test runs of deposition welding with copper powder. In this process – also known as laser cladding – the blue laser beam creates a molten pool on the surface of the workpiece. With the aid of a powder nozzle, the copper is added at the same time so that it can be melted in the same beam. After a short cooling time, the workpiece and copper powder are now metallurgically bonded together. In addition, the welding process causes very little distortion and the coating is extremely durable. Here, too, the process is similar to that one of the laser in the infrared wave spectrum. Furthermore, the coating is electrically conductive due to the physical properties of copper.

Cladding with Copper Powder

Particularly good results were already achieved with the blue laser when cladding with copper powder on workpieces made of steel materials. Thanks to the high absorption of the blue laser beam, direct deposition welding of copper powder onto a copper substrate is now possible for the first time.

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