Apparatus for shielding an electrical circuit from electromagnetic interference

• US 4,829,432 A
• Filed: 12/28/1987
• Issued: 05/09/1989
• Est. Priority Date: 12/28/1987
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Stevens, Carl, Ozug, Peter, Hershberger, Marc
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): THOMPSON, GREGORY D
• Application Number:
  US07/138,276
• Time in Patent Office: 498 Days
• Field of Search: 174/35 R, 174/35 MS, 174/35 FC, 174/51, 361/212, 361/220, 361/393-395, 361/399, 361/422, 361/424
• US Class Current: 361/818
• CPC Class Codes: H05K 9/0045 being rigid plastic containers having a coating of shielding material
• CPC Class Codes: Y10S 174/34 PCB in box or housing

Abstract

Apparatus is disclosed for shielding an electric circuit, mounted on a circuit board, from electromagnetic interference (EMI). The electrical circuit is mounted on one side of a circuit board. A conductive layer on the other side of the circuit board functions as a ground plane. An enclosure of insulating material is open on one side and has an inside surface of electrically conductive material. The circuit board and enclosure are joined together so that the electrical circuit on the circuit board is substantially completely surrounded by the electrically conductive material on the inside surface of the enclosure and by the ground plane of the circuit board. Thus, there is provided an effective EMI shield for the electrical circuit.

Claims

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.

2. The invention of claim 1 wherein said interfitting means includes ledges which project inwardly from an opposing pair of walls of said side walls of said enclosure, said ledges supporting said circuit board within said enclosure.