Assertion: circuit board's layer | /r/AtLocation | hard base
Facets:
Source sentences:
text: In 1943, the Austrian Paul Eisler, working in the United Kingdom, patented a method of etching the conductive pattern, or circuits, on a layer of copper foil attached to a hard base that did not conduct electricity.
text: In 1943, the Austrian Paul Eisler, working in the United Kingdom, patented a method of etching the conductive pattern, or circuits, on a layer of copper foil attached to a hard base that did not conduct electricity.