Hot Chips 2026: SK hynix pushes hybrid bonding to HBM5 as AI memory hits 775-micron ceiling — firm extends MR-MUF through Nvidia Rubin
- ID
- 17329
- Status
- summarized
- Published
- 25 Aug 2026, 1:55 AM
- Fetched
- 25 Aug 2026, 6:15 AM
- Provider
- Tom's Hardware
- Category
- technology
- Original URL
- https://www.tomshardware.com/tech-industry/semiconductors/sk-hynix-says-hybrid-bonding-wont-be-ready-for-hbm4e-as-ai-memory-runs-into-a-775-micron-ceiling
- Source URL
- https://www.tomshardware.com/feeds/all
Summary
- Score
- 5.5
- Created
- 25 Aug 2026, 6:16 AM
- Tags
- Audience
- ai-ml-learnerssaas-startup-founders
What happened
SK hynix VP Jaesik Lee confirmed at Hot Chips 2026 that hybrid bonding won't be ready for HBM4E, pushing the transition to HBM5 at the earliest. HBM cubes are physically capped at 775 microns (a 300mm wafer's thickness), so adding layers requires thinner dies and narrower gaps — 16-Hi HBM4 already thins core dies to ~50 microns and halves inter-die gaps versus 12-Hi. SK hynix is extending its MR-MUF packaging through Nvidia Rubin, with 12-Hi HBM4 in mass production and 16-Hi at 48GB per cube in customer qualification.
Why it matters
If you're budgeting AI infrastructure or planning GPU procurement over the next 18-24 months, the delayed hybrid bonding transition means HBM supply constraints and per-cube capacity gains will come from increasingly aggressive die thinning rather than a packaging breakthrough — expect continued tight supply and high prices for high-capacity HBM variants through the Rubin generation.
Discussion angle
What does a 775-micron physical ceiling mean for AI memory scaling — are we approaching diminishing returns on HBM capacity, and how does that affect GPU pricing and availability for builders who can't lock in enterprise supply deals?