Hynix launched 36-layer 128Gb 3D NAND chips in April 2016, started production of 48-layer 256Gb 3D NAND chips last November and says it will start mass production of 72-layer 3D NAND in H2.

The 72-layer device stacks 1.5x more cells than a 48-level device, says Hynix, read and write are 20% faster

Hynix reckons the NAND flash market will be worth $46.5 billion this year and $56.5 billion in 2021.