Granted Patent
Utility
US 4,302,273 · App. 06/156,889
Etching tank in which the solution circulates by convection
Inventor:
Thomas B. Howard
Patented Case
View Patent ↗
Granted: Nov 24, 1981
Filed: Jun 4, 1980
Inventor
Thomas B. Howard
Assignee (at issue)
RCA Corporation
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.