High purity phenyl silicone ladder polymer and method for producing the same
CA 2008679 C · Owner: Okahashi, Kazuo · Inventors: Hayashi, Osamu; Adachi, Etsushi; Okahashi, Kazuo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
High purity phenyl silicone ladder polymer and a, method for producing such polymer suitable for use as, the protective film the interlayer insulating film, etc. in the fabrication of semiconductor elements which, polymer contains therein 1 ppm or below of each of sodium, potassium, iron, copper, lead and chlorine and 1, ppb or below of each of uranium and thorium and which is, represented by the following general formula (I): (I), (where: R1 to R4 denote respectively hydrogen or a lower alkyl group; n is an integer of from 8 to 1,000); or the following general formula (II):, (II), (where: n is an integer of from 8 to 1,600).
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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 26, 1990 and granted March 12, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 26, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 26, 2012.
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Timeline
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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.