Joining structure of thin metal plate and base material, and welding method of thin metal plate and base material

1. A welding method comprising:

overlapping a thin metal plate with a base material, the thin metal plate being coated with an insulator, and setting an annular welding schedule line on a welding schedule portion of the thin metal plate, the welding schedule portion being a metal exposed portion where the insulator is removed;

forming a welding line such that a continuous irradiation with a laser light from a fiber laser is performed while moving the laser light along the welding schedule line, and while vibrating the laser light across the welding schedule line; and

setting a length of the welding line such that an entire inside of the welding schedule line is welded.

2. The welding method according to claim 1 , further comprising

using a single-mode fiber laser as the fiber laser.

3. The welding method according to claim 1 , wherein:

the setting of the welding schedule line includes coaxially setting a plurality of the welding schedule lines, and

the setting of the length of the welding line includes setting the length of the welding line to a length to restrain a welding line of an outer welding schedule line from overlapping a welding line of an inner welding schedule line.

4. The welding method according to claim 1 , wherein

the forming of the welding line includes forming the welding line such that adjacent welding lines contact or overlap one another in a direction along the welding schedule line.

5. The welding method according to claim 1 , further comprising:

coating the thin metal plate with the insulator; and

removing the insulator on the welding schedule portion of the thin metal plate.