SK Hynix HBM4 Production Milestones and NVIDIA Requirements
SK Hynix has started HBM4 production because customers demand greater performance than existing products can deliver. SK Hynix has begun HBM4 mass production because the company reached its first production milestone for HBM4 on February 2026. The company needs to start production six months before its delivery date because NVIDIA requires extensive quality testing which creates complicated testing procedures.
The HBM4 development project faces its main obstacle which requires achieving performance standards that exceed existing benchmarks. HBM4 has a base standard which allows 8 Gbps per pin, but NVIDIA requires 11.7 Gbps to run its upcoming Rubin AI accelerators. The speed increase of 46% has caused stability problems during 2.5D packaging testing.
- Current Performance The initial batches needed to redesign circuits because they could not sustain stability at 11.7 Gbps.
- Market Adjustment Industry analysts suggest NVIDIA will lower its requirements to 10 Gbps (20 TB/s total bandwidth) for the first Rubin shipments because it needs to maintain stable supply chains.
- Supply Chain Outlook SK Hynix will remain the top HBM4 supplier because it maintains current yield stability despite facing technical challenges.
HBM4 now supports 2,048 input/output (I/O) ports which represents a twofold increase over the previous generation. The new density creates problems because it generates electrical noise which interferes with power delivery when power needs to be transmitted to the uppermost stack layers. SK Hynix has developed a specialized packaging solution.
Increased Die Thickness SK Hynix has stopped excessive DRAM layer thinning for certain DRAM layers. The company intends to ensure chip protection against performance decline through die maintenance by keeping a thick core die.
Reduced Inter DRAM Spacing The space between stacked DRAM layers must decrease because thicker dies require more space to stay within the 775 micrometer height limit. The space reduction directly impacts power efficiency and data latency while it creates challenges for Molded Underfill (MUF) material injection because it leads to potential defects.
Multiple companies compete against each other to develop HBM4 technology. SK Hynix currently operates 1b DRAM (5th Gen 10nm) with TSMC 12nm logic die. Samsung Electronics operates 1C DRAM with TSMC 4nm logic die. Two companies use different integration levels which requires SK Hynix to depend on its new packaging verification method to resolve potential I/O interference and power delivery issues.
The success of these packaging refinements is critical for the launch of NVIDIA’s Rubin chips in the second half of 2026. The AI hardware market will experience delayed product launches if memory performance fails to achieve the 22 TB/s bandwidth requirement. SK Hynix has reached the final verification stage for its packaging method which enhances HBM4 stability without needing any major new facility construction work.
