onsemi Mountain Top wafer fab (formerly Fairchild Semiconductor)
Large load · 125 CRESTWOOD DRIVE, Mountain Top, PA
The 200 mm wafer fab in Mountain Top, Pennsylvania is being sold by onsemi to Silex Microsystems, a Swedish MEMS foundry. The deal was announced on July 7, 2026 for USD 40 million, with closing expected around year-end 2027 or January 2028, subject to CFIUS approval. onsemi says it will move the site's current products to other facilities during an extended transition. The fab currently employs about 130 people.
Overview
Silex Microsystems entered into a definitive agreement to acquire the 200 mm integrated circuit fab from Semiconductor Components Industries, LLC, onsemi's entity, for USD 40 million. The purchase is an asset deal covering the production facility, real estate, infrastructure and manufacturing equipment, with USD 10 million paid as a deposit at signing and USD 30 million at closing. Silex describes the transaction as a lower-risk alternative to a greenfield build, since it is buying and converting an existing fab. Closing is subject to customary conditions and approval from the Committee on Foreign Investment in the United States. Silex plans to convert the site into a MEMS fab it calls Silex U.S. Fab.
Profile
- Facility size and workforce
- The fab has about 3,000 square metres of existing cleanroom space, with roughly 12,000 square metres available for future expansion. Evertiq reports that the cleanroom is about double the footprint of Silex's existing facility in Järfälla, Sweden. Silex will not assume onsemi's existing revenue from integrated circuit production. About 130 people currently work at the site, and Silex intends to offer them employment once it owns the assets. Silex's target is EBIT break-even between 2029 and 2030, with revenue and profitability comparable to its Swedish 200 mm fab by 2034.
- onsemi's transition and cost savings
- onsemi announced the Mountain Top sale on July 7, 2026 as part of its Fab Right manufacturing strategy, which directs resources to its most competitive and scalable operations. The company said the extended transition period is intended to allow an orderly transfer of the products currently manufactured at the site to other facilities within its network. onsemi also agreed to divest a second facility, and it has a long-term supply agreement for its Tarlac, Philippines site. The two divestitures together are expected to save about $35 million a year, with savings starting in 2027 and the full benefit in 2028.
Facility
- Activity
- 200 mm integrated circuit wafer fabrication
- Industry
- Manufacturing
- Site type
- Facility
- Operating status
- Operating
Related records
Timeline
- Jul 7, 2026
- onsemi and Silex Microsystems announced a definitive agreement for the Mountain Top fab at USD 40 million.
Silex establishes U.S. manufacturing capacity – acquires semiconductor fab in Pennsylvania | Placera.se
- Jul 7, 2026
- onsemi said the transaction is expected to close in January 2028, with transition of current products to other sites.
onsemi Advances Fab Right Strategy with Agreements to Divest Two Manufacturing Facilities | Placera.se