Definition

Multi-Chip Module (MCM) substrates require PCB fabrication with HDI-class features: fine lines (≤75 µm), micro-vias, and tight tolerances for interconnecting multiple dies. When you receive an MCM design for fabrication, expect requirements similar to BGA substrate builds: thin cores, sequential lamination, and often embedded passives. MCM-L (laminate-based) substrates use standard PCB processes but at the high end of capability.