Granted Patent
Utility
US 4,933,158 · App. 07/425,957
Method for purifying nitrogen trifluoride gas
Inventors:
Makoto Aritsuka, Naruyuki Iwanaga
Patented Case
View Patent ↗
Granted: Jun 12, 1990
Filed: Oct 24, 1989
Inventors
Makoto Aritsuka
Naruyuki Iwanaga
Assignee (at issue)
Mitsui Toatsu Chemicals, Incorporated
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.