Amkor Technology announced Phase 2 of its Arizona advanced packaging and test campus, expanding total investment to $12 billion. Phase 2 is scheduled to break ground in late 2027 and reach completion in late 2029.
The most informative part of this announcement is not the investment figure. It is that Phase 1's cleanroom capacity is already oversubscribed by customer commitments before it operates.
Spoken for before it is built
Phase 1's cleanroom covers 33,000 square meters. Customer commitments exceeding that capacity means demand to secure advanced packaging inside the US is running ahead of supply. The Phase 2 announcement reads naturally as a response to that excess demand.
Amkor's Arizona campus is the first US high-volume advanced packaging site operated by an OSAT (outsourced semiconductor assembly and test provider). Combined headcount across Phases 1 and 2 is expected to exceed 3,500.
Total investment
Expanded to $12 billion with the Phase 2 announcement.
Phase 1 status
33,000 square meters of cleanroom. Customer commitments exceed the capacity ceiling.
Phase 2 schedule
Groundbreaking planned for late 2027, completion expected late 2029.
Headcount
Over 3,500 expected at the Arizona site across Phases 1 and 2 combined.
Position
First US high-volume advanced packaging site operated by an OSAT.
Back-end remains the bottleneck
Advanced packaging has repeatedly surfaced as a constraint on AI semiconductor supply. We have covered ABF substrate capacity expansion and ASE's panel-level packaging production, and every layer — materials, equipment, assembly — remains tight against demand.
Amkor's oversubscription is a data point showing that pattern in a US context. As front-end fab investment advances across countries, the question of whether back-end capacity is keeping up gets an answer here: at Amkor's Arizona site, at least, it is not.
Implications for sourcing plans
Looking at the schedule, Phase 2 breaks ground in late 2027 and completes in late 2029. More than three years separate the announcement from capacity actually arriving. If advanced packaging demand keeps growing over that window, the squeeze continues.
For anyone planning procurement around US advanced packaging capacity, the fact that Phase 1 is already committed cannot be overlooked. Securing new allocation means either waiting for Phase 2 or negotiating with other sites and providers. In projects where geopolitical considerations make domestic production a requirement, this timeline becomes a binding constraint.
At the same time, an OSAT holding a high-volume site inside the US changes the structure of available options. High-volume advanced packaging has concentrated in Asia, with limited geographic diversity. Once Amkor's Arizona campus runs at full scale, the supply chain gains a geographic alternative — with the caveat that the effect arrives from late 2029 onward, a timeline worth building into plans.