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New approaches on laser micro welding of copper by using a laser beam source with a wavelength of 450 nm
摘要： Laser micro welding is specified with welding geometries below 1 mm and is used with increasing demand for contacting electronic components such as battery and fuel cells. Fiber lasers with a wavelength in the near infrared range (IR, λ ≈ 1 μm) have established themselves for this purpose. The laser welding process allows processing of parts in the micron range but reduces the surface quality of the processed parts at the same time. Furthermore, weld defects can occur due to process instabilities caused by the low absorptivity (<5%) of copper for infrared radiation. Therefore, alternative laser beam sources and processes have to be established, to avoid these negative effects on the weld seam quality. Laser beam sources in the visible wavelength range (VIS) prove to be an alternative due to an increased absorption of the laser energy in copper-based alloys. This paper presents the observation of laser micro welding of Cu-ETP and CuSn6 specimen with a thickness between 150 μm and 1 mm. The diode laser is specified by a wavelength of 450 nm and a nominal output power of 150 W. The surface roughness of the weld seam and the overall weld seam geometry for heat conduction welding are investigated. The laser energy absorption is measured using two integrating spheres to compare the results quantitatively to measurements conducted with laser sources of 1070 nm and 515 nm. For detailed observation high speed imaging is used to observe the melt pool dynamics. Simulations are conducted, to optimize the dimensioning of optics and laser beam source. Finally, the possible use of the novel laser beam source for various technical joining applications is discussed and evaluated and the influence of the use of protective gas is observed.
关键词： heat conduction welding,scanner system,laser micro welding,copper,modelling,450 nm
更新于2025-09-23 15:21:01
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Process studies on copper laser beam welding over gap by using disc laser at green wavelength
摘要： The increasing demand for the substitution of the internal combustion engine vehicles to the battery electric vehicles requires beside battery cells high performance power electronic devices such as power control units (PCU). However, a combined requirement of high junction temperature stability and a large joint area of the interconnection on the PCU is a challenge for the conventional joining method such as soldering and wire bonding process. The Laser Impulse Metal Bonding (LIMBO) process enables a high temperature stable weld joint and large joint area. During the LIMBO process only minimized thermal stress is induced into the underlying substrate by a spatial separation between both joining partners in an overlap configuration with a gap. Hence, an energetic separation between the melting and joining phase is given. In this paper, the LIMBO process is firstly investigated with the disc laser at wavelength λ = 515 nm. Due to the enhanced absorptivity of the laser beam at this wavelength on copper material, the process duration of the LIMBO process is about the half compared to the LIMBO process with wavelength λ = 1064 nm.
关键词： Shadow projection,Green laser beam,Heat conduction welding mode,Laser beam micro joining,LIMBO
更新于2025-09-23 15:19:57
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Temperature distribution during laser based heat conduction welding of CFRP
摘要： For the implementation of carbon fiber reinforced (CFRP) parts, these need to be assembled to more complex structures. Therefore, laser transmission welding was transferred to heat conduction welding for joining thermoplastic CFRP to itself. The goal of these investigations was to determine the influence of the focal point geometry and the main fiber orientation within the CFRP on the temperature distribution at the upper joining member. A set-up was chosen consisting of two thermo cameras in order to measure the process temperatures on top and underneath the upper joining member. Furthermore, the heat affected width was determined and correlated to the process temperatures.
关键词： seam strength,carbon fiber,thermoplastic,contour welding,process temperture,heat conduction welding
更新于2025-09-12 10:27:22
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Laser welding of copper using a high power disc laser at green wavelength
摘要： The trend towards renewable energies and electromobility is increasing the demand for copper. Laser welding as a flexible and fully automatable process is being more frequently employed to join copper materials. The use of green laser radiation compared to infrared laser radiation has the advantage of a significantly higher absorption coefficient for copper materials. Therefore, high power laser sources emitting at a green wavelength promise a more stable and a more efficient process. In this paper, experimental investigations with a green continuous wave laser radiation at a maximum power of 1 kW are presented. Using design of experiments, the process limits are determined depending on the laser power and the welding velocity. Furthermore, the potential of heat conduction welding using this laser source is investigated.
关键词： Green wavelength,Laser material processing,Heat conduction welding,Process limit,Copper
更新于2025-09-12 10:27:22