SK hynix has shared a notable update on one of the most important packaging advances in the high bandwidth memory (HBM) race: the company says it has improved yields for its hybrid bonding technology, a next-generation method designed to build faster, denser HBM stacks. The news was revealed by SK hynix technical leader Kim Jong-hoon during an advanced packaging conference in South Korea, signaling that the company’s work on hybrid bonding is moving closer to practical, large-scale use.
Hybrid bonding matters because it changes how stacked memory is physically connected. Today’s HBM is made by stacking multiple DRAM dies (memory layers) and linking them using microscopic bumps, then completing the final package. Most current HBM stacks commonly use 8 to 12 layers. That approach works, but it becomes increasingly challenging as the industry pushes toward even more layers to boost bandwidth and capacity.
Next-generation standards such as HBM4 and HBM5 are expected to demand higher performance and larger capacities without allowing the overall package to grow much in size, since space on advanced accelerators and compute boards is limited. This is where hybrid bonding stands out. Instead of relying on bumps between layers, it bonds dies through direct contact, reducing the distance signals and heat have to travel. In simple terms, removing bumps can help enable tighter stacking, higher speeds, and better efficiency, while also limiting heat buildup.
According to SK hynix, progress is already tangible. Kim Jong-hoon said the company has verified a 12-die HBM stack using hybrid bonding. Just as important, he indicated that SK hynix is now focused on raising yield to a level suitable for mass production, adding that preparations are “much further along than in the past,” even though specific yield numbers were not disclosed. Yield is crucial because even impressive technical demos can remain stuck in the lab if manufacturing consistency isn’t strong enough for volume shipments.
Until hybrid bonding is fully ready for production, SK hynix plans to continue using its Mass Reflow-Molded Underfill (MR-MUF) process. MR-MUF still uses copper bumps, but it aims to reduce the gap between dies by heating the entire stack and filling the spaces with an underfill material. It’s an advanced approach that supports current HBM products while the company works toward a bump-less hybrid bonding future.
Although HBM is most often associated with data centers, AI accelerators, and enterprise-scale computing, progress in HBM packaging can eventually benefit consumers as well. Better bandwidth and efficiency can translate into faster performance in downstream products over time. That said, cutting-edge HBM is still likely to remain expensive and constrained in availability in the near term, largely due to intense demand from the data center market.
About the author: Ramish is a seasoned technology writer and editor with more than a decade of experience. He specializes in semiconductor fabrication and market analysis. With a background in finance and supply chain management—via a bachelors in Finance and a micromasters in supply chain management from MIT—Ramish combines financial rigor with deep industry insight to deliver accurate and authoritative coverage.
