SK hynix and SanDisk unveil first High-Bandwidth Flash (HBF) standard specification with Google and ecosystem partners adopting the new storage standard designed for AI accelerators.

On August 3, marking the opening day of the Flash Memory Summit 2026 in California, SK Hynix and SanDisk jointly released the first standard specification for High Bandwidth Flash (HBF). The two companies had reached an intent to cooperate in August 2024 and officially established the HBF Alliance under the OCP (Open Compute Project) framework in February 2025. The move from formal alliance establishment to standard specification took just six months.

The HBF Alliance brings together SK Hynix, SanDisk, Google, and AI chip startup Tenstorrent. Google's participation is significant, as it signals that HBF was designed from inception to address the actual needs of hyperscale data centers rather than remain a laboratory concept.

HBF occupies a new storage tier between HBM (high bandwidth memory) and SSDs. As the AI industry transitions from model training to inference, a critical tension has emerged: HBM offers high bandwidth but limited capacity at high cost, making it difficult to support large model parameters, while SSDs provide abundant capacity but face hardware bottlenecks in read and write speeds that cannot meet real-time inference requirements. HBF combines NAND flash with 3D stacking technology derived from HBM manufacturing processes, aiming to deliver both high bandwidth and substantial capacity for AI inference servers.

The specification defines two capacity configurations based on 8-layer and 16-layer NAND chip stacking, supporting up to 512GB. Bandwidth is available in three grades, ranging from approximately 0.4TB/s to 3.0TB/s. HBF uses the industry-standard UCIe interconnect interface, enabling flexible adaptation to different processor architectures including GPUs and CPUs. OCP released the specification as an open industry standard rather than a proprietary solution.

At the summit, SK Hynix also unveiled its 10th-generation (V10) 375-layer 4D NAND flash for the first time, achieving 2.5 times greater energy efficiency than its previous generation, with mass production expected in early 2026. The company indicated it will leverage this opportunity to drive large-scale HBF implementation across the AI storage market.

Google's participation has been instrumental in building HBF ecosystem momentum. The success of HBF ultimately depends on how quickly and widely hyperscale data center operators adopt the technology. The finalized standard specification provides a clear foundation for achieving this goal.