Laser Copper Welding with
Blue High-Power Diode Laser

445 nm wavelength and 3000 W laser power (CW) open up new possibilities for the high-quality, spatter-free laser welding of copper and the effective processing of gold and other non-ferrous metals in industrial series production.

Copper, Gold and Other Non-Ferrous Metals

The industrial laser beam sources that were previously available required increased effort to satisfactorily process highly reflective metals, such as copper,in series production. Blue laser light offers new opportunities because copper and gold, above all, absorb the blue light spectrum seven to twenty times better thanlaser radiation in the infrared range (see diagram).

Now, the first high-power diode laser that considerably improves the laser material processing of non-ferrous metals has been developed. Thin foils and sheets, in particular, can be processed much more effectively with the blue laser, but the blue LDM diode laser offers even more advantages, too.

Edge Welding and Welding of Copper Foils

In addition to the high absorption of blue light, which makes it much easier to melt copper, the use of the intensity profile characteristic of diode lasers also contributes to the top-notch processing outcome. Furthermore, Laserline’s proven diode laser technology allows the laser power to be finely graduated within milliseconds, thus adapting it perfectly 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 was begun. They have excellent electrical conductivity and produce only a few spatters on adjacent areas of the material. Material efficiency is also particularly high, as the blue laser, on the one hand, does not require any overlap or material reinforcement in the seam area, and on the other hand, liquid copper has a high gap bridgeabilityfor processing with blue laser radiation. The option of controlled heat conduction welding enables copper to be used as the upper joining component when welding different metals, for the first time. Copper powder and thin copper foils can even be joined to other materials, such as steel and aluminum. When it comes to welding foils, considerable results have already been achieved in butt and edge welding.

The total energy consumption required for welding copper has been 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 enough for welding copper and 0.5 kW for welding gold, instead of 10 kW.

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

Copper Welding

Copper welding has been revolutionized by the development of a new blue diode laser. The blue laser beam copper and other non-ferrous metals to undergo high-quality processing within industrial processes.

The Process

For the first time, the blue laser makes it possible to undertake controlled heat conduction welding of copper and other non-ferrous metals with low material thicknesses: material thicknesses of less than one millimeter are no longer a problem. While 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. The blue laser beam melts the desired material along the joints, then 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. In principle, the process is the same as with an infrared laser – apart from the wavelength used.

Welding of Copper Pins with a Blue Diode Laser

Welding of two copper pins (approx. 0.5x1.5mm²) with 450nm wavelength and 100ms pulse time for electrical applications.

Heat conduction welding with the LDMblue blue diode laser leads to a very stable, homogeneous molten pool without any evaporation. The dominant surface tension of the liquid copper bridges the gaps between the pins, resulting in a homogeneous connection.

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Excellent Results

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

Various Surface Structures of Copper after Welding

Heat Conduction Welding of Copper with a wavelength of 450nm

Bead on plate weld on a pure copper sheet (0.5mm thickness) with the Laserline LDMblue 500-60.

Heat conduction welding with a wavelength of 450 nm and a focus diameter of 600 µm ensures a highly stable molten pool without spatters during the welding process.

Laser: LDMblue 500-60
Copper sheet: 0.5mm
Focus diameter: Ø0.6mm

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Journal

About welding copper components

In our series “Diode lasers and their applications”, we offer a regular insight into the most important applications based on diode lasers. And one field of application, in particular, should not be forgotten: copper welding.

But why is this special application so important? Copper is one of the most important raw materials for electrical signal transmission and thus a key component of many modern technologies. In battery cells of mobile devices, in induction coils or in accumulators of electric cars, copper segments can today be found everywhere. Often the components are exposed to a high current, high operating temperatures and strong vibrations. This significantly affects the production process: When components are made of several parts, the joining seams must be highly solid and must not create additional resistances in the signal flow to prevent an increased temperature in the component. As brazed joints often lack the required head resistance, weld seams created by lasers are the best option here.

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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 and Additive Manufacturing with Copper Powder

The blue laser is particularly well suited for deposition welding or additive manufacturing with copper. The low energy absorption (lower than 10%) of highly reflective metals such as copper or gold in the wavelength range of 1,000 nm, proves to be a major challenge for standard IR lasers. The high initial intensities required, induce processes often characterized by turbulent melt pools and spatter formation, which are critical factors in the processing of electrical components.

Here, the blue laser achieves excellent results in copper processing because more than 50% absorption is achieved. We obtain an enormously calm process that does not require any additional power control. A powder efficiency of more than 80% can be achieved during the process, which is exceptionally good for copper-based components. Thus, even workpieces made of steel materials can be processed outstandingly with copper powder.

However, the blue laser is not limited to processing non-ferrous metals. Excellent results can also be achieved when processing other metals, such as steel or nickel.

LDMblue

LDMblue revolutionizes the processing of copper, gold and other highly reflective metals in multiple ways

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