China's 15th five-year plan elevates PCB role in AI supply chains

Reclassifying PCB from passive substrate to strategic AI compute node is a structural policy redefinition, not incremental subsidy. The technical ripple is immediate: upstream low-Dk resins and ultra-thin copper foil jump in domestication priority, while downstream CoWoS-class packaging lines accelerate localization. Mirroring the 2019 photoresistor substitution arc, expect a functional-but-suboptimal domestic substrate window within 18 months. Risk calculus: Ibiden and Unimicron's oligopoly over ABF substrates, compounded by US bonding-equipment export controls, creates a structural break risk in China's design-to-package chain. Dual-sourcing mandates before 2026 will push per-line compliance costs up 15-25%. Strategic positioning: Ibiden will likely lock in mainland capacity to hedge policy exposure; Shennan and WUS ride the subsidy tailwind into mid-tier HDI; NVIDIA and AMD face an uncomfortable bifurcation between de-risking and localizing. Twelve-to-twenty-four-month outlook: advanced packaging substrates will replicate the 2020-22 memory chip overbuild-glut-consolidation cycle, compressed by roughly 30%. The real inflection point is 2027—whether domestic 16+ layer ABF substrates pass reliability qualification at leading AI chip fabs will define the ceiling of China's compute sovereignty.