Non-metallic chassis structure with electromagnetic field attenuating capability

• US H526 H
• Filed: 10/19/1987
• Issued: 09/06/1988
• Est. Priority Date: 02/26/1985
• Status: Abandoned Application

• Current Assignee: Martin B. Miller
• Original Assignee: Martin B. Miller
• Inventors: Miller, Martin B.
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): Wallace, Linda J.
• Application Number:
  US71/120,07
• Time in Patent Office: 323 Days
• CPC Class Codes: H05K 9/0045 being rigid plastic containers having a coating of shielding material

Abstract

An electronic equipment chassis structure using non-metallic plastic material such as epoxy-impregnated fiberglass together with layers of shielding metal film, preferably of copper overlaid by nickel. Desirable radio frequency shielding is achieved in comparison with the metal chassis structures and in the presence of decreased chassis mass, lower fabrication cost and chassis change enabling flexibility. Examples of material characteristics, representative fabrication costs, and attained radio frequency attenuation properties are included.

Claims

1. Electronic apparatus comprising:

interference active radio frequency means emitting or spuriously responding to radio frequency energy signals;

low mass chassis means supporting, enclosing, and shielding said active radio frequency means, said chassis means including;

an organic material substrate member configured to support said active radio frequency means, said substrate member including a first exterior surface area portion and a second interior surface area portion;

a homogeneous first metallic film layer electrical shield coating disposed over said first exterior surface area portion of said substrate member; and

a homogeneous second metallic film layer magnetic shield coating differing in composition from said first metallic film layer coating and disposed over said first metallic film layer in intimate physical contact therewith.

2. The apparatus of claim 1 further including:

a homogeneous third metallic film layer electrical shield coating disposed over said said second interior surface portion of said organic material substrate member and identical in composition with said first metallic film layer electrical shield coating; and

a homogeneous fourth metallic film layer magnetic shield coating differing in composition from said third metallic film layer electrical shield coating and disposed over said third metallic film layer coating in intimate physical contact therewith, said fourth metallic film layer coating being identical in composition with said second metallic film layer coating.

3. The apparatus of claim 2 further including an additional homogeneous thin metallic film coating layer means located intermediate said substrate member and said first metallic film layer coating for enhancing the adhesion between said substrate and said first metallic film layer coating.

4. The apparatus of claim 2 wherein said first metallic film layer electrical shield coating is composed of copper.

5. The apparatus of claim 4 wherein said second metalic film layer coating is composed of nickel.

6. The apparatus of claim 5 wherein said substrate member is composed of epoxy-impregnated fiberglass.

7. A lightweight chassis for use with radio frequency electromagnetic interference active electronic apparatus comprising:

an organic material substrate member configured to a closable geometric shape and having a plurality of first intersecting planes surface portions;

closure means closing said substrate member, said closure means including second surface portions;

means located on selected of said first and second surface portions mounting components of said electronic apparatus;

a multi-layered elecromagnetic radiation energy shielding and physical protection coating located on said first and second surface portions, said coating also including;

a first homogeneous metallic copper film electrical shielding layer disposed over reverse faces of said substrate member and closure means in intimate physical contact therewith; and

a second homogeneous metallic nickel film magnetic shielding layer disposed over said first film layer on said substrate member and closure means in intimate physical contact therewith.

8. The chassis of claim 7 further including shielding divider elements located within said closable geometric shape and connected with one of said substrate member and closure means.

9. The chassis of claim 7 wherein said organic material substrate is comprised of fiberglass cloth impregnated with epoxy resin.

10. The chassis of claim 9 further including an adhesion-promotion thin coating layer intermediate said substrate member and closure means surface portions and said first metallic film layer.

11. The chassis of claim 10 further including a tin-lead solder electrical connection with said nickel metallic film layer.

19. The chassis of claim 10 wherein said adhesion-promoting thin coating layer comprises a layer of nickel.

12. A method for making a non-metallic electrostatic field and electromagnetic field shielding chassis for an electronic apparatus comprising the steps of:

forming an open sided closable chassis structure, having interior and exterior surfaces, from a pliable non-metallic substrate material;

adding electronic component supporting elements to said chassis structure;

ossifying said pliable material into a rigid fixed shape;

covering said chassis structure interior and exterior surfaces with a first metallic film layer of good electrical conductivity; and

coating said first metallic film layer with a second and different metallic film layer on both said interior and exterior surfaces.

13. The method of claim 12 wherein said step of adding electronic component supporting elements includes perforating said chassis structure.

14. The method of claim 12 further including the step of forming an open sided closure member capable of cooperating with said chassis in forming a closed structure and ossifying with said chassis in forming a closed structure and ossifying said closure members.

15. The method of claim 12 wherein said pliable substrate material includes fiber reinforcing material.

16. The method of claim 12 further including the step of applying an adhesion-promoting layer to said chassis structure prior to said covering step.

17. The method of claim 12 wherein said covering step includes depositing said first film layer using a chemical precipitation deposition sequence.

18. The method of claim 12 wherein said coating step includes electroplating.