Plessey Semiconductors
Cheney Manor, Swindon, Wilts. SN2 2QW

GEC Plessey Semiconductors
Swindon

Set up in 1952, Plessy Semiconductors became Europe's largest semiconductor company, but was was taken over by by a consortium formed by GEC and Siemens in 1989.

In 2010, a new company using the previous name was set up, with products having nothing to do with old Plessey and GEC products.

One of the business units in the Plessey consortium of companies was Plessey Semiconductors, based in Swindon / Wiltshire County.

After Plessey's new Communications Division was formed in 1951, a licence was obtained from the US company Philco for the manufacture of semiconductors; the two companies set up a joint venture.

Factory and headquarters of the company were built on the new Cheney Manor Trading Estate in 1952. It became an important part of the Plessey operation with finally three new sites in Swindon. In 1957, manufacture of transistors began at Swindon, one of the first semiconductor factories in the UK. Three types of transistor – germanium alloy, diffused alloy and silicon alloy – were produced with the Philco Corporation process.

In 1958 Royal Radar Establishment placed a contract with Plessey for integrated circuits. Plessey's involvement with manufacturing IC’s began at the start of the 1960s.

In 1961, Philco pulled out of the Semiconductors Joint Venture, selling its shares to Plessey.
1966 MOS integrated circuits were produced at Swindon, making Plessey the first European manufacturer of such microcircuits.

Subsequently Plessey gained considerable experience with a wide range of planar diodes and transistors, developed entirely within Plessey. The original development and pilot production was done at the Allan Clark Research Centre at Caswell and the larger scale manufacture was undertaken at the semiconductor factory at Swindon which undertook a large expansion in 1967. Plessey believed that in 1967 it had Europe’s most advanced silicon integrated circuit production facility.

1988 Plessey acquired Ferranti Semiconductors, creating Europe's largest semi-custom chip company. A new state-of-the-art silicon chip production facility near Plymouth was opened.

From 1989, when Plessey was taken over by a consortium formed by GEC and Siemens, the semiconductor activities were known as 'GEC Plessey Semiconductors' . The chip-making operations of GEC, Plessey and Ferranti were folded into one medium-sized chip company – GEC Plessey Semiconductors (GPS) – with the analogue operation spun off separately as Zetex Semiconductor.

1996 with a new Managing Director of GEC a major reorganisation was aimed. This involved , among others , the sale of GEC Plessey Semiconductors to Mitel in Canada.

In 1998, Zarlink Semiconductors, originally part of Mitel, acquired GEC-Plessey Semiconductors and continued to run a design centre, sales office and manufacturing facility at Plessey's original factory in Cheney Manor.

In 2002, Zarlink sold the old GPS Roborough fab to X-Fab of Germany. After the sale of the Roborough site in Plymouth, the original Plessey Semiconductors site at Cheney Manor, Swindon continued to operate under the Zarlink Semiconductor name. Employing over 400 people, the factory survived until 2008 when under recessionary pressure it was sold by Zarlink to Plus-Semi, a company that continued in Swindon until 2010 when it was relaunched as Plessey Semiconductors.

The new Plessey Semiconductors Ltd, established in 2010, acquired their current Headquarters in Roborough, Plymouth.

Demolition of the former Plessey Semiconductors factory Cheyney Manor in Swindon occured in July 2012.