Laser soldering method and device

An automatic soldering device including a laser soldering device, a Z-axis drive device driving the laser soldering device in an up-down direction, and a control device controlling operations of the laser soldering device and the Z-axis drive device,

• wherein the laser soldering device comprises:
• a body having a lower opening, an image capturing hole in communication with the lower opening, and an irradiation hole in communication with the lower opening;
• a mirror guiding the laser light to the lower opening by reflecting the laser light or allowing the laser light to pass therethrough, and guiding light having entered the lower opening by reflecting the light or allowing the light to pass therethrough,
• an image capturing device capturing an image of a workpiece through the image capturing hole and the mirror;
• a laser device constituted by a single laser light source;
• and
• an optical fiber guiding laser light from the laser device to enter the irradiation hole;
• and
• wherein the control device executes:
• a first height adjustment step of adjusting, by the Z-axis drive device, a height of the laser soldering device to a position at which the laser light has a preset irradiation diameter D1 larger than a diameter of a solder droplet S when viewed from above;
• a preliminary heating step of sending an irradiation command to the laser device, and irradiating the solder droplet S with the laser light to heat the solder droplet S to a temperature at which a flux solvent component volatilizes and a solder powder does not melt;
• a second height adjustment step of adjusting, by the Z-axis drive device, the height of the laser soldering device to a position at which the laser light has a preset irradiation diameter D2 smaller than the diameter of the solder droplet S when viewed from above;
• and
• a main heating step of sending an irradiation command to the laser device, the irradiation command causing the laser device to emit the laser light with a higher output than in the preliminary heating step, irradiating the solder droplet S with the laser light to heat the solder droplet S to a temperature at which the solder powder melts, and performing soldering.