Contactless soldering process using semiconductor laser diode with 915 nm wavelength

Laser technology has gained an important place in industrial production processes today and offers various advantages in many areas. Lasers attract attention with their high energy density, precise control, contactless operation and effective processing capabilities on various materials. In particular, the use of lasers in applications such as processing, cutting, welding and soldering of materials stands out with features such as high precision, fast processing, non-contact operation and low thermal deformation. These properties are of great importance, especially in fields such as microelectronics, optoelectronics, medical devices and the automotive industry. In addition, advantages of lasers operating with 915 nm wavelength, such as compact structure, energy efficiency and low maintenance requirements, are among the reasons why they are preferred in industrial applications. In this study, the laser beam coming from the fiber of a fiber-coupled laser diode with a wavelength of 915 nm was narrowed through a plano-convex lens. Pieces of SAC305 solder scattered on a piece of ceramic were positioned under this narrowed laser light. A continuous wave current between 10 W and 80 W was applied to the laser diode and it was aimed to melt these solder pieces with the laser. Then, a series of experiments were carried out by giving quasi-continuous wave currents to the laser diode. The fact that a laser operates on quasi-continuous wave means that the power supply is only on for certain periods of time. These intervals are short enough to significantly reduce thermal effects, but still long enough to allow laser processing. Various parameters were determined with the data obtained from these trials. These parameters that will change the way the laser diode drives are different pulse width, different frequency, different duty cycle and different peak current values. Soldering experiments were carried out on a circuit board using leaded and lead-free solder wires with a 915 nm wavelength fiber-conjugated laser diode driven by these different parameters. Laser beams with a wavelength of 915 nm coming from the fiber-coupled laser diode were directed to the solder pad on the circuit board through a plano-convex lens. A series of experiments were carried out by driving the laser diode with different driving parameters in order to solder the legs of the resistors attached to the solder pad to the circuit board. These experiments were recorded with a thermal camera. Thanks to the data obtained from the thermal camera, the temperature change occurring during the soldering process was analyzed. The graphs of these temperature changes and the visuals of the soldering processes were interpreted and a conclusion was drawn. This study aims to experimentally analyze the effectiveness and performance of lasers with a wavelength of 915 nm in soldering processes. The 915 nm wavelength has high absorption properties, especially in metal materials, which provides high efficiency in soldering processes. As a result of this study, using a semiconductor laser diode with a wavelength of 915 nm (driven by a correct peak current in a semi-continuous waveform with the correct pulse width, correct frequency and correct duty cycle parameters), it has been observed that, thanks to the local and instantaneous heating process, non-contact soldering processes can be carried out, especially for thermally sensitive components. The results obtained will provide a detailed evaluation of the general importance of laser soldering and the performance of lasers with a wavelength of 915 nm in soldering processes.