Glossary term
Substrate
The foundation layer in chip packaging connecting the die to the circuit board; advanced substrates are constrained alongside CoWoS.
A Substrate is the foundation layer in chip packaging that connects the silicon die to the printed circuit board, routing power and signals between them. Advanced substrates for high-end accelerators are a supply constraint in their own right, alongside CoWoS packaging capacity. The substrate layer is a quieter but real bottleneck in the advanced-packaging chain. See Packaging Bottleneck 101.