The Anandtech review says it's nickel plated. The sticker is also a copper heat spreader: "The Samsung Phoenix controller introduces a nickel-coated heatsprea

The Anandtech review says it's nickel plated. The sticker is also a copper heat spreader: "The Samsung Phoenix controller introduces a nickel-coated heatspreader, and the 970 EVO retains the copper foil layer in the label on the back of the drive that was introduced with the 960 generation, but there are no more serious cooling measures on the drive."