Green laser has various advantages in copper welding, such as high reproducibility, high welding quality, and highly stable processing regardless of the surface condition of copper. Taking advantage of this feature, it is becoming an important tool for welding EVs key components, motors and batteries, that contribute to carbon neutrality. The latest green laser, 3 kW green laser, is equipped with a beam profile control technology “BrightLine Weld” that is highly effective in reducing spatter. With this technology, green laser has expanded its application. The latest green laser technology that contributes to carbon neutrality with high-quality copper welding is introduced in this paper.

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Due to considering about SDGs in the world, the recent well-known revolution is a changing from conventional mobility to “E-mobility”. In the environment, the motivation of develop lasers process is very high and key because of non-contact, selective and less heat affected zone for the manufacturing of car itself and the related components. Example, one of new application for contribution of the reduction of CO₂ is laser drying of Battery slurry. BMBF in Germany has started project about this application and aiming to improve manufacturing efficiency to save energy. This laser drying application is not completely new idea, but it is result of the change of viewpoint. The laser source for this application is direct diode laser which has high WPE, and homogeneous top hat beam, so, it contributes for Carbon neutral society. Another important laser application is welding process of copper material and dissimilar metal material like a aluminum with copper for motor, inverter, secondary battery. For conventional IR laser systems with keyhole welding is not possible to have smooth surface and high-quality welding due to the low absorption and the high heat conductivity of copper. Due to this, new CW blue laser that is wavelength of 450 nm enables a reproducible of pure copper material with a precise energy deposition. In direct comparison between the IR and the blue, the IR depicts instable welding conditions resulting in a missing weld or highly varying welding depth. With the application of the wavelength of 450 nm, a melting of copper material in the heat conduction mode is possible for the first time, allowing the precise adjustment of the melt pool geometry. Processing these materials with near infrared wavelength is possible but requires a high average power and has further disadvantages as soon as the copper melts. Absorption and heat conductivity change substantially when melting copper making the process instable. To overcome this problem green wavelength had been initially investigated, the results had been better than IR lasers, but still the complex optical set-up required for the frequency conversion to generate green laser light poses challenges. On the other hand, there is another solution for these material welding is about IR+blue Hybrid laser solutions. Also, Laserline has introduced 3 kW blue laser in the market in April 2022, so, this power range can expand applications for EV development.

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EV/LIB, which is noted for the CN contribution, has been growing steadily year after year due to corona trouble. I visited the Shenzhen headquarters of China UW, which has Occupancy of China NO.1 as a laser for EV/LIB. This paper reports the current status and future development of the CN contribution by the EV/LIB laser in China, the visible hybrid laser represented by the blue laser, and the invisible hybrid laser by near Red LD and fiber laser. In the UW, we have succeeded in commercializing a blue DDL hybrid laser equipped with a super compact 500W blue laser in the head for the first time in the world, and we report its workability and future possibility.

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The spread of xEVs is expected to increase due to the green growth strategy associated with carbon neutrality. Blue diode lasers are expected to be a very effective solution to the surging demand for processing motors, batteries and inverters where many copper materials are used. In this technical review, examples of copper welding and copper coating using the blue diode laser of Shimadzu Corporation are presented, and the results of verification of processing quality using our microfocus X-ray CT system are reported.

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In recent years, the electrification of automobiles has been accelerating against the backdrop of global tightening of regulations to reduce CO₂ emissions, but there are issues for the spread of EVs, such as short cruising range and high body prices. To overcome these problems, miniaturization and weight reduction of batteries and motors that are power sources are being studied, and laser processing technology with high precision and high work efficiency in the manufacturing process, especially fiber laser processing technology, is attracting attention. On the other hand, copper processing using a fiber laser has problems such as a large amount of spatter. Therefore, we have developed the Blue-IR hybrid laser BRACE®X, an industrial laser optimized for copper processing by combining a near-infrared fiber laser and a blue direct diode laser. In this explanation, based on the experimental result about basic processing principle in copper processing using a Blue-IR hybrid laser, the four features of “spatter suppression”, “penetration stability”, “robustness to surface state”, and “low heat input processing” are explained. Furthermore, as an introduction of processing application examples, the results of copper plate lap welding simulating the busbar welding process, flat wire welding simulating the motor manufacturing process, and laminated copper foil and plate welding simulated battery manufacturing process are reported.

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High-quality copper welding is particularly important for variable devices in next generation automotive application, for example, motor core, lithium-ion battery, power semiconductor devices. Conventional IR laser in not suitable for copper welding because of its low optical absorption ratio. On the other hand, optical absorption ratio of copper in 450 nm wavelength is 65%, which is highly effective for laser welding. I this paper, copper welding results by utilizing blue and IR hybrid system are described. Attention is paid to improvement of optical absorption ratio of IR laser by assistance of blue laser.

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The flux-wall guided transfer mode in submerged arc welding was mo deled by a particle method and simulated in two dimensions. Moreover, numerical experiments were conducted to investigate the effect of driving forces acting on the molten metal on this transfer mode. As a result, the flux-wall guided transfer was successfully simulated, in which the molten metal droplet left the wire tip while impacting a cavity wall. This computational result showed that a liquid column was formed at the wire tip by the Lorentz force, and then the column was pushed up by the cavity pressure and grown horizontally. Then, molten metal droplets collided with the cavity wall, detached from the wire tip, and were transported toward weld pool and base metal. In addition, from numerical experiments using this computational model, it was suggested that both Lorentz force and cavity pressure were important factors for this metal transfer mode.

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