HBF – High Bandwidth Flash. This is the stacking of NAND dies one above the other with them all above a logic layer. The whole stack connecs to a GPU. CPU, TPU or other processor server via an interposer unit, just like high-bandwidth memory (HBM). Western Digital’s Sandisk business unit publicized the idea in February 2025.
The aim is to place higher-capacity NAND in the stack layers to replace lower capacity and more expensive HBM. The whole stack has interposer-class connectivity to the server host.
