🟠 It blows up the physical size of the substrate.
SemiAnalysis Twitter · SemiAnalysis (@SemiAnalysis_) · 2026-07-03
SemiAnalysis explains that SPHBM4's high-speed serial lanes extend memory placement distance to 20mm from the GPU die, enabling larger chip packages with more HBM per unit and dramatically increasing substrate material consumption per chip.
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Extraction
Topics: sphbm4ai-chip-packagingsubstrateshbmchip-design
Claims
- Traditional HBM must be placed within microscopic millimeters of the GPU because wide parallel signals degrade instantly over distance.
- SPHBM4's high-speed serial lanes allow HBM to sit up to 20mm away from the GPU die.
- The extended placement distance enables more HBM stacks per package as chip packaging footprints expand significantly.
- Larger chip packaging footprints dramatically increase the total square footage of substrate material required per chip.
Key quotes
Traditional HBM must sit microscopic millimeters away from the GPU because wide parallel signals degrade instantly over distance.
Because SPHBM4 uses high-speed serial lanes, memory can sit up to 20mm away. This extra breathing room means there is room for more HBM per package, as chip packaging footprints get much larger, dramatically driving up the total square footage of substrate material needed per chip.