Fabrication process of sio2 electrets and to the electrets obtained
CA 2113048 C · Owner: Lewiner, Jacques · Inventors: Lewiner, Jacques; Perino, Didier
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
For making an SiO2 electret, a layer of SiO2 is formed on a solid substrate (5) by direct deposition in vapor phase starting from a plasma containing silicon and oxygen and the layer so formed (10) is subjected to a thermal treatment by raising its temperature to above 100°C during a time period longer than 1 hour before being electrically charged.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed January 7, 1994 and granted August 7, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 7, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 7, 2016.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.