Conductive elastomers and methods for fabricating the same

• US 5,949,029 A
• Filed: 10/28/1996
• Issued: 09/07/1999
• Est. Priority Date: 08/23/1994
• Status: Expired due to Fees

• Current Assignee: Thomas & Betts International Incorporated (ABB Limited)
• Original Assignee: Thomas & Betts International Incorporated (ABB Limited)
• Inventors: Goodwin, Jonathan W., Michaud, Arthur G., Crotzer, David R., DeDonato, David A.
• Primary Examiner(s): Sough, Hyung Sub
• Assistant Examiner(s): SILVERIO, WILLIAM R
• Application Number:
  US08/736,830
• Time in Patent Office: 1,044 Days
• Field of Search: 428/209, 428/901, 428/323, 174/254, 174/256, 174/250
• US Class Current: 174/254
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: H01H 1/029 comprising conducting material dispersed in an elastic support or binding material
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 2209/014 composed of different layers; Lubricant in between
• CPC Class Codes: H01H 2239/034 Environmental protection
• CPC Class Codes: H01L 2224/29099 Material
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00013 Fully indexed content
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01R 12/52 connecting to other rigid printed circuits or like structures
• CPC Class Codes: H01R 12/714 with contacts abutting directly the printed circuit; Button contacts therefore provided on the printed circuit
• CPC Class Codes: H01R 13/035 Plated dielectric material
• CPC Class Codes: H01R 13/2414 conductive elastomers
• CPC Class Codes: H01R 13/6599 Dielectric material made conductive, e.g. plastic material coated with metal
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 2201/0133 Elastomeric or compliant polymer elastomeric conductor H05K2201/0314
• CPC Class Codes: H05K 2201/0245 Flakes, flat particles or lamellar particles
• CPC Class Codes: H05K 2201/0329 Intrinsically conductive polymer [ICP]; Semiconductive polymer
• CPC Class Codes: H05K 2203/1168 Graft-polymerization
• CPC Class Codes: H05K 3/102 : by bonding of conductive powder, i.e. metallic powder H05K3/12 takes precedence
• CPC Class Codes: H05K 3/325 : by abutting or pinching, i.e. without alloying process; mechanical auxiliary parts therefor adaptations of leads inserted in holes for press-fit connections H05K3/308
• CPC Class Codes: H05K 3/38 : Improvement of the adhesion between the insulating substrate and the metal
• CPC Class Codes: H05K 3/386 : by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: H05K 9/0039 : Galvanic coupling of ground layer on printed circuit board [PCB] to conductive casing printed shielding conductors, ground planes or power planes for reduction of cross-talk or noise in printed circuits H05K1/0218
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Abstract

Several different types of electrically conductive elastomers are disclosed along with the methods for their fabrication. In one particular embodiment, a layered composition is disclosed which comprises a substrate, a first layer, and a second layer. The substrate is formed of a non-conductive elastic material and it has an outer surface. The first layer, which is formed with a non-conductive elastic material, is grafted to the outer surface of the substrate. The second layer, which is formed with a non-conductive elastic material having a quantity of conductive flakes interspersed therein, is grafted to an outer surface of the first layer. The second layer can further be formed with a quantity of rounded or jagged conductive particles interspersed in the non-conductive elastic material such that some of the conductive particles are present along an outer surface of the second layer. Alternatively, a quantity of rounded or jagged conductive particles may be imbedded in an outer surface of the second layer.

Claims

1. A layered composition comprising:

a substrate, said substrate having an outer surface, said substrate being formed of a non-conductive elastically resilient material;

a first layer having a first surface and a second surface, the first surface thermally grafted directly to at least a portion of said outer surface of said substrate, said first layer being formed of a non-conductive elastically resilient material; and

a second layer having a first surface and a second surface, said first surface thermally grafted directly to at least a portion of said second surface of said first layer, said second layer being formed of a non-conductive elastically resilient material having a quantity of conductive flakes interspersed therein.

2. The layered composition as defined in claim 1, wherein the thermal grafting of said first layer and said second layer is performed by a single process.

3. The layered composition as defined in claim 1, wherein said conductive flakes are formed of a solid conductive material.

4. The layered composition as defined in claim 1, wherein said conductive flakes are formed of a semiconductive material that is coated with a conductive material.

5. The layered composition as defined in claim 1, wherein said conductive flakes are formed of a non-conductive material that is coated with a conductive material.