Welding device for button-type secondary battery

1 . 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.

2 . The welding device of claim 1 , wherein a first gap is defined between the two probes through which the current flows, and a second gap is defined between the two probes connected to the voltmeter, and

wherein the first gap is larger than the second gap.

3 . The welding device of claim 2 , wherein the two probes through which the current flows are mounted on the jig, and the two probes connected to the voltmeter are mounted on the base.

4 . The welding device of claim 2 , wherein the two probes through which the current flows are mounted on the base, and the two probes connected to the voltmeter are mounted on the jig.

5 . The welding device of claim 1 , wherein the probes are disposed to be spaced a predetermined distance from a point at which the laser light is irradiated.

6 . The welding device of claim 1 , wherein the jig is capable of ascending and descending to approach the base when descends and to be away from the base when ascends.

7 . The welding device of claim 1 , wherein each of the probes includes a pogo pin that overcomes elastic force of a spring therein and is pressed.

8 . The welding device of claim 7 , further comprising a controller that calculates resistance of each of the welding portions by calculating the current supplied from the power source and the voltage measured by the voltmeter, and compares the calculated resistance with input data to determine whether a welding defect occur.

9 . The welding device of claim 7 , wherein, when the probes are mounted on the base or the jig, the probes are electrically insulated from the base and the jig.

10 . The welding device of claim 1 , further comprising a controller to calculate resistance of each of the welding portions by calculating the current supplied from the power source and the voltage measured by the voltmeter, and compares the calculated resistance with input data to determine whether a welding defect occur.

11 . The welding device of claim 3 , further comprising a controller to calculate resistance of each of the welding portions by calculating the current supplied from the power source and the voltage measured by the voltmeter, and compares the calculated resistance with input data to determine whether a welding defect occur.