Cu-Ni-Si-based copper alloy plate having excellent deep drawing workability and method of manufacturing the same

A Cu—Ni—Si-based copper alloy plate comprising:

• 1.0 mass % to 3.0 mass % of Ni;
• 0.2 mass % to 0.8 mass % of Sn;
• 0.3 mass % to 1.5 mass % of Zn;
• 0.001 mass % to 0.2 mass % of Mg;
• and
• Si at a concentration of ⅙ to ¼ of a mass % concentration of Ni,
• with a remainder of Cu and inevitable impurities,
• wherein, an average value of aspect ratios (a minor axis of crystal grains/a major axis of crystal grains) of each crystal grains in an alloy structure is 0.4 to 0.6, an average value of GOS in all crystal grains, which is measured through an EBSD method using a scanning electron microscope equipped with an electron backscatter diffraction image system, is 1.2° to 1.5°, wherein a boundary for which an orientation difference between adjacent pixels is 5° or more as a crystal grain boundary, by measuring orientations of all pixels in a measurement area range;
• and a ratio (Lσ/L) of a total special grain boundary length Lσ of special grain boundaries to a total grain boundary length L of crystal grain boundaries is 60% to 70%, a spring bending elastic limit becomes 450 N/mm2 to 600 N/mm2, a solder resistance to heat separation is favorable and deep drawing workability is excellent at 150° C. for 1000 hours.