Zn alloy plated steel sheet having excellent phosphatability and spot weldability and method for manufacturing same

A method of manufacturing a zinc alloy plated steel sheet, the method comprising:

• preparing a zinc alloy plating bath including 0.5 wt % to 2.8 wt % of Al and 0.5 wt % to 2.8 wt % of Mg, with a remainder of Zn and inevitable impurities;
• immersing a base steel sheet in the zinc alloy plating bath, and obtaining a zinc alloy plated steel sheet by performing plating;
• gas wiping the zinc alloy plated steel sheet;
• primary cooling the zinc alloy plated steel sheet at a primary cooling rate of 5° C./sec or less (excluding 0° C./sec) to a primary cooling end temperature of more than 380° C. to 420° C. or less, after the gas wiping;
• maintaining the zinc alloy plated steel sheet at a constant temperature for at least one second at the primary cooling end temperature, after the primary cooling;
• and
• secondary cooling the zinc alloy plated steel sheet at a secondary cooling rate of 10° C./sec or more to a secondary cooling end temperature of 320° C. or less, after the maintaining the zinc alloy plated steel sheet at a constant temperature.