NVIDIA Cancels Rubin Ultra Development After CoWoS-L Warping Failures
The cancellation explains Rubin Ultra's disappearance from NVIDIA's roadmap and the sudden NVL576 stopgap, signaling a manufacturing limit in TSMC's CoWoS-L that forced a redesign.
Reporting from 1 source: ASCII.jp.
NVIDIA canceled original Rubin Ultra development after CoWoS-L interposer warping made prototypes non-functional. The 180-layer CoWoS-L warped in multiple directions, causing dies and wiring to peel. NVIDIA shifted to calling a different configuration Rubin Ultra and introduced a stopgap NVL576 rack solution using eight NVL72 (V2) units.
Rubin Ultra was to pair four GPU dies with eight HBM4E stacks on a 9.5-reticle CoWoS-L interposer planned for 2027. The 180-layer wiring layer warped in multiple directions when manufactured, peeling dies and wiring and leaving the interposer non-functional. The first prototype failed in early 2026, and a second prototype also failed, prompting the cancellation.
NVIDIA and TSMC began redesigning after the first failure, but uncertainty persisted through March, which is why Rubin Ultra stayed on the roadmap at GTC. The current plan reuses the Rubin Ultra name for a different configuration. The NVL576 rack solution announced at GTC, built from eight NVL72 (V2) units on the Oberon Rack, appears to be a stopgap to reach 576 GPUs without the original Rubin Ultra.
Synthesized by Yomimono from the 1 cited source below, including Japanese-language reporting where cited, then editorially reviewed before publishing.