The Kaukauna-based owner of four specialty paper mills in northeastern Wisconsin has been sold to a company in Finland. The 615-million dollar deal is expected to be complete by the second half of this year. Expera has a total of 18-hundred employees working at mills in Kaukauna, De Pere, Rhinelander, and Mosinee. No changes in operations are anticipated. New owner Ahlstom-Munksjo is based in Helsinki. Expera Specialty Solutions was formerly known as Thilmany, and also owns the Nicolet Mill in De Pere. The Kaukauna paper mill has been operating for 135 years.