Apparatus for shielding an electrical circuit from electromagnetic interference

Claim 1

The invention comprising a substantially flat, rectangular circuit board having extended upper and lower sides and first, second, third and fourth peripheral edges between said upper and lower sides; an electrical circuit which is surface mounted on a predetermined region on one of said upper or lower sides of said circuit board; an electrically conductive ground layer provided on the other side of said circuit board, said ground layer being at least coextensive with said predetermined region of said one side of said board and extending to the peripheral edges of said board; an open-sided rectangular enclosure of insulating material having a bottom wall and first, second, third and fourth contiguous side walls connected to said bottom wall, said enclosure having an electrically conductive inner layer covering the inner surfaces of said bottom wall and said first, second, third and fourth side walls of said enclosure; means for interfitting said circuit board within said enclosure, so that said predetermined region of said one side of said board, on which said electrical circuit is mounted, is enclosed by said conductive inner layer of said enclosure, and, so that said ground layer on said other side of said board, (1) is adjacent to the conductive inner layer on the inner surfaces of said first, second, third and fourth walls of said enclosure, and, (2) forms an electrically conductive wall closing off said open sided enclosure; and electrically conductive means for electrically connecting said ground layer on said circuit board to said conductive inner layer of said enclosure, to provide an effective shield for said electrical circuit on said board.