Welding device for button-type secondary battery

A welding device, which welds an electrode tab protruding from an electrode assembly of a button-type battery to a can of the button-type battery in which the electrode assembly is mounted, the welding device comprising:

• a base configured to support a bottom surface of the can with an inner surface of the can facing in an upward direction, and the electrode tab with a lower surface of the electrode tab being in contact with the inner surface of the can;
• a jig disposed on the base to fix the electrode tab to the inner surface of the can, the jig having an opening hole through which a laser light for welding the electrode tab to the can passes;
• a laser irradiation device configured to irradiate the laser light to the opening hole when the jig fixes the electrode tab to the can;
• and
• four probes mounted on the base or the jig,
• wherein two probes of the probes are connected to a power source so that current flows to welding portions of the can and the electrode tab when the probes are in contact with the welding portions, and the remaining two probes are connected to a voltmeter to measure voltages at the welding portions to be in contact with the welding portions,
• wherein two probes of the four probes are on the jig at opposing sides of the opening hole and configured to contact an upper surface of the electrode tab, and
• wherein two probes of the four probes are on the base and configured to contact the bottom surface of the can.