Method of making a gasket for an electronics enclosure to help keep out electrical interference

• US 4,662,967 A
• Filed: 09/10/1984
• Issued: 05/05/1987
• Est. Priority Date: 01/05/1983
• Status: Expired due to Fees

• Current Assignee: Keene Corp. (Steel Partners Holdings LP)
• Original Assignee: Keene Corp. (Steel Partners Holdings LP)
• Inventors: Meeks, Robert E., Bogan, John J.
• Primary Examiner(s): Weston, Caleb
• Application Number:
  US06/631,483
• Time in Patent Office: 967 Days
• Field of Search: 156/242, 156/245, 174/35 R, 174/35 GC, 174/35 MS, 252/511, 252/512, 252/514
• US Class Current: 156/242
• CPC Class Codes: B29C 70/78 Moulding material on one side only of the preformed part
• CPC Class Codes: B29C 70/882 partly or totally electrically conductive, e.g. for EMI shielding conductive floors or floor coverings H05F3/025; EMI shielding in general H05K9/00
• CPC Class Codes: B29K 2083/00 Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as moulding material
• CPC Class Codes: B29K 2105/16 Fillers
• CPC Class Codes: B29K 2995/0005 Conductive
• CPC Class Codes: B29L 2031/265 Packings, Gaskets
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H05K 9/0015 Gaskets or seals

Abstract

A method of making a shielding gasket integral with a surface comprising the steps of (a) preparing a gasket material consisting of a mixture of an elastomer, a conductive filler, a catalyst and a bonding agent; (b) filling a mold with the gasket material; (c) covering the mold with a surface chosen to be bonded to the gasket; and (d) curing the gasket material in contact with the surface to utilize the bonding agent to bond the gasket material to the chosen surface. The article fabricated by this method comprises a gasket (18b), consisting of a mixture of an elastomer (26), a conductive filler (30) and a bonding agent (28), bonded to a surface (38) by the bonding agent during curing and having the particles comprising the conductive filler held in physical contact with the surface and with one another by the elastomer to which the particles are bonded.

Claims

1. The method of making a shielding gasket integral with a surface comprising the steps of:

(a) preparing a gasket material consisting of a mixture of an elastomer, a conductive filler, a catalyst and a bonding agent;

(b) filling a mold with said gasket material;

(c) covering said mold with a surface chosen to be bonded to said gasket material; and

(d) curing said gasket material in contact with said surface to utilize said bonding agent to bond said gasket material to said surface;

said mold having at least one groove therein to receive said gasket material and at least one groove to receive a mixture of an elastomer, a catalyst and a bonding agent adapted to form an environmental gasket bonded to said surface upon being cured.

2. The method of claim 1 wherein said environmental gasket is cured simultaneously with said shielding gasket.

3. The method of claim 1 wherein said environmental gasket is cured subsequent to said shielding gasket.

4. A method of making a compressible shielding gasket integral with a mating surface, for repetitive use and reuse in compression contact between said surface and another closure surface;

in the finished gasket there being an electrically conductive filler dispersed throughout an elastomeric matrix, the filler being fixedly bonded in place to the elastomer;

said method comprising the steps of;

(a) preparing a mold as the reverse shape of a gasket;

(b) preparing an elastomer of relatively high compressibility;

(c) adding to the elastomer a catalyst;

(d) adding to the elastomer a conductive filler to impart electrical conductivity to the elastomer;

(e) adding to the elastomer a bonding agent;

(f) mixing the elastomer, catalyst, conductive filler and bonding agent to form a gasket material throughout which the elastomer and the bonding agent are in initmate contact with the filler and with one another;

(g) then filling the mold with said gasket material;

(h) covering the mold with such a mating surface chosen to be bonded to said gasket material so that one side only of the material contacts the surface; and

(i) then simultaneously;

(1) bonding, by virtue of the bonding agent, the elastomer to the conductive filler throughout the material,

(2) bonding, by virtue of the bonding agent, the elastomer to the surface where the material is in contact with the surface to form a unitary gasket-and-surface combination, at one side only of the material, that is repetitively reusable in a compression contact between the surface and such other closure surface, and

(3) curing the elastomer to form a free surface of the gasket material where the material is in contact with the mold to provide a gasket that is repetitively reusable in a compression joint.

5. The method of claim 4:

wherein the elastomer-to-filler bonding step (i)(1) imparts vibration resistance but also tends to decrease compressibility of the finished gasket; and

also comprising the step of;

(j) selecting for use as the elastomer in step (a) an elastomer of low durometer on the order of ten;

wherein the selecting step (j) counteracts the tendencies of the filler-adding step (d) and of the elastomer-and-filler-bonding step (i)(1) to decrease compressibility, and causes the gasket to be adequately compressible for use in such a compression joint.

6. The method of claim 4 wherein:

the elastomer-to-filler bonding step (i)(1) imparts vibration resistance but also tends to decrease compressibility of the finished gasket; and

said mold is the reverse shape of a gasket with a plurality of ribs;

whereby the method produces a gasket that has a plurality of ribs to enhance the overall compressibility of the gasket.

7. The method of claim 4 wherein:

steps (b) and (d) comprise adding approximately sixty percent by volume of the elastomer approximately forty percent by volume of the conductive filler;

step (c) comprises adding a quantity of a catalyst between one-half percent and five percent by weight of the elastomer;

step (e) comprises adding a quantity of a bonding agent between one-half percent and two percent by weight of said elastomer; and

step (f) comprises heating the gasket material to an elevated curing temperature, and maintaining said gasket material at that temperature while applying an elevated curing pressure.

8. The method of claim 7 wherein:

said mold is the reverse shape of a gasket with a plurality of ribs;

whereby the method produces a gasket that has a plurality of ribs to enhance the overall compressibility of the gasket.