US5399295A
Expired / Lapsed
US
⏱️ 0.0 years remaining
EMI shielding composites
Assignee: Dow Chemical Co
•
Filing: 1993-07-29
•
Granted: 1995-03-21
•
Expires: 2013-07-29
Abstract
Abstract A composite sheet is disclosed comprising a continuous matrix of a synthetic resinous material having randomly dispersed therein conductive fibers and a particulate, conductive or semi-conductive filler. In addition to providing excellent EMI shielding properties, the composite sheets are formable and are of sufficient strength to act as structural components.
Inventors
- 👤 Jeffrey Gamble
- 👤 Larry D. Yats
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:37
CPC Classifications
H; H05; H05K; H05K9/00; H05K9/0073; H05K9/0081; H05K9/0088; C; C08; C08K; C08K7/00; C08K7/02; C08K7/04; H01; H01B; H01B1/00; H01B1/20; H01B1/22; H01B1/24; Y; Y10; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249924; Y10T428/24994; Y10T428/249948; Y10T428/25; Y10T428/30
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
95 words
A composite sheet comprising (a) a continuous matrix of a polymeric resin, having randomly dispersed therein; (b) from about 0.05 to about 30 weight percent of the composite of a fine particulate conductive or semi-conductive filler material, and (c) from about 0.25 to about 45 weight percent of the composite of conductive fibers having an aspect ratio from 25 to 2000, a diameter of from 2.5 μm to 50 μm, and a length from 1.6 mm to 25 mm, said fibers being randomly oriented in two dimensions substantially in the plane defined by the sheet.
Claim 2
Dependent Claim
95 words
A composite sheet comprising (a) a continuous matrix of a polymeric resin, having randomly dispersed therein; (b) from about 0.05 to about 30 weight percent of the composite of a fine particulate conductive or semi-conductive filler material, and (c) from about 0.25 to about 45 weight percent of the composite of conductive fibers having an aspect ratio from 25 to 2000, a diameter of from 2.5 μm to 50 μm, and a length from 1.6 mm to 25 mm, said fibers being randomly oriented in two dimensions substantially in the plane defined by the sheet.
Claim 3
Dependent Claim
29 words
The composite sheet of claim 1 wherein said conductive fibers have an average length of from 4.0 to 13.0 mm and a diameter of from 6.5 to 25.0 micrometer.
Claim 4
Dependent Claim
19 words
The composite sheet of claim 1 wherein the aspect ratio of said conductive fibers is from 200 to 1,800.
Claim 5
Dependent Claim
33 words
The composite sheet of claim 1 wherein said composite sheet comprises from 2 to 35 percent conductive fibers and from 0.1 to 5 percent filler material, based on the weight of the composite.
Claim 6
Dependent Claim
21 words
The composite sheet of claim 4 wherein said filler material has a resistivity of from 10 -2 to 10 9 ohms-cm.
Claim 7
Dependent Claim
23 words
The composite sheet of claim 5 wherein said filler material is a furnace carbon black having a resistivity of less than 10 ohm/cm.
Claim 8
Dependent Claim
31 words
The composite sheet of claim 1 wherein said conductive fibers are selected from selected from the group consisting of stainless steel, nickel, carbon, graphite, metallized glass, metallized graphite or metallized plastic.
Claim 9
Dependent Claim
23 words
The composite sheet of claim 1 wherein said conductive fibers are nickel-coated graphite or aluminum-coated glass and said filler material is carbon black.
Claim 10
Dependent Claim
22 words
The composite sheet of claim 1, wherein said composite sheet includes from 25 to 50 percent by weight of non-conductive reinforcing fibers.
Claim 11
Dependent Claim
13 words
The composite sheet of claim 9, wherein said reinforcing fibers are glass fibers.
Claim 12
Dependent Claim
30 words
The composite sheet of claim 1 wherein said sheet has an EMI shielding effectiveness of greater than 20 to 80 decibels under conditions as specified by ASTM Designation ES 7-83.
Claim 13
Dependent Claim
31 words
The composite sheet of claim 1 wherein said sheet is capable of dissipating an electrostatic charge of +5 kv or -5 kv to 0 percent of total charge within 2 seconds.
Claim 14
Dependent Claim
31 words
The composite sheet of claim 12 wherein said sheet is capable of dissipating an electrostatic charge of +5 kv or -5 kv to 0 percent of total charge within 0.5 seconds.
References Cited (Backward Citations)
US4435465A
Cited
EP0090432A2
Cited
EP0103695A1
Cited
US4566990A
Cited
US4973514A
Cited
US5004561A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-03-20 | 1998-09-19 | 1999-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-20 | 2002-09-19 | 2003-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-20 | 2006-09-19 | 2007-03-21 | $7700.00 | Window Closed / Lapsed |