Laser processing method, laser welding method, and laser processing apparatus

A laser welding method, comprising:

• a beam-splitting step for splitting a single laser beam into a plurality of laser beams including a zero-order diffracted laser beam by diffracting the single laser beam by a diffractive optical element;
• a direction setting step of turning an array of focused beam spots obtained from the plurality of laser beams about the zero-order diffracted laser beam in accordance with a direction of an array of a plurality of welding points at which parts mounted on a printed circuit board are welded to the board;
• an interval setting step for causing an interval between the focused beam spots in the array to be in agreement with an interval between the plurality of welding points in the array by adjusting the distance from the diffractive optical element to the board;
• and
• a connecting step for increasing the intensity of the plurality of laser beams to such an intensity that is necessary for welding, and connecting the parts to the board by simultaneously irradiating the plurality of welding points with the focused beam spots in the array having the direction and the interval determined in the preceeding steps.

A laser apparatus comprising:

• a laser oscillator;
• a diffractive optical element for splitting a single laser beam emitted from the laser oscillator into a plurality of laser beams that include a zero-order diffracted laser beam and are used in processing;
• a turning unit for setting the diffractive optical element at a a desired angle by turning it about the optical axis thereof;
• and
• a moving unit for positioning the diffractive optical element on the optical axis by sliding it over a desired distance along the optical axis;
• wherein:
• the diffractive optical element is one-dimensional relief grating;
• the zero-order diffracted laser beam is in alignment with the optical azis and in agreement with a processing point;
• and
• the moving unit positions the diffractive optical element such that the plurality of laser beams are in agreement with an interval between a plurality of processing points.