In re Ehrreich

590 F.2d 902, 200 U.S.P.Q. (BNA) 504, 1979 CCPA LEXIS 323
CourtCourt of Customs and Patent Appeals
DecidedJanuary 11, 1979
DocketAppeal No. 78-561; Serial No. 379,784
StatusPublished
Cited by16 cases

This text of 590 F.2d 902 (In re Ehrreich) is published on Counsel Stack Legal Research, covering Court of Customs and Patent Appeals primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
In re Ehrreich, 590 F.2d 902, 200 U.S.P.Q. (BNA) 504, 1979 CCPA LEXIS 323 (ccpa 1979).

Opinions

RICH, Judge.

This appeal is from the decision of the Patent and Trademark Office (PTO) Board of Appeals (board) affirming the rejection of claims 1-45, all of the claims in application serial No. 379,784, filed July 16, 1973, for reissue of U. S. Patent No. 3,583,930, entitled “Plastics Made Conductive With Coarse Metal Fillers.” The board affirmed the examiner’s rejection of all claims as obvious under 35 U.S.C. § 103. In addition, the examiner’s rejection of claims 1-8, 12-24, 26-31, 33-36, 38 — 43, and 45 under 35 U.S.C. § 112 was sustained by the board. We reverse.

The Invention

Appellants’ invention pertains to improved electrically-conductive coatings, gaskets, and caulking compounds useful for waveguide assemblies, weathertight R.F. (radio frequency) enclosures, and other applications requiring environmental sealing and electromagnetic radiation (EMR) shielding. A compressible or resilient plastic material is loaded with silver-coated metal particles which are held in electrically-conductive, metal-to-metal contact by the plastic binder or matrix. Appellants’ improvement resides in their discovery that high-volume loadings of the plastic material, in the order of 35 to 80 volume percent, utilizing large particles (0.5 to 40 mils) having a high surface area per unit volume, i. e., between 450 to 200,000 square feet/cubie foot, results in a product having high conductivity, and, hence, good EMR shielding capability. The invention may be better understood from an examination of claims 1, 9, and 12, the only independent appealed claims. Claim 12 is the broadest claim:

12. In an electromagnetic energy shield having a volume resistivity to be effective as an electromagnetic shield comprising a resin matrix loaded with particles coated with silver in an amount of about 40 to 80 volume percent, the improvement being that the silver coated particles are of a maximum size in the range of from 0.5 to 40 mils and wherein the resin in [sic] compressible.

Claim 1 is the same except for being limited to an EMR shield “in the form of a gasket or caulking compound.” Claim 9 is limited to an EMR shield in the form of a gasket wherein the particles are spherical:

9. An electromagnetic energy shield in the form of a gasket having a volume resistivity to be effective as an electro[904]*904magnetic energy shield comprising a compressible resin matrix loaded with substantially spherical particles coated with a layer of silver and ranging in size from 0.5 to 40 mils.

The Prior Art

The following references were cited by the examiner and relied on in various combinations to support the rejection of the claims under § 103:

Wood 2.313.379
McGrath 2,506,728
Coleman et al. 2.771.380
Price 3,030,237
Ueda 3,083,169
Hunter 3,099,578
March 9, 1943
May 9, 1950
Nov. 20, 1956
April 17, 1962
March 26, 1963
July 30, 1963
Cuming, W. R., “Materials for R. F. Shielded Chambers and Enclosures,” Symposium Digest. 4th National Symposium on Radio Frequency Interference, June 28-29, 1962.

Ueda discloses thermally and electrically-conductive plastics made by mixing a water-soluble phenolic resin with ultra-fine (approximately 0.1 n) powders of carbon in combination with similarly sized powders of various metals. His normally hard product may be made flexible by the addition of polyvinyl alcohol to the phenolic resin mixture. Ueda states that the superior conductivity of his composition is due largely to the presence of the water in the phenolic mixture. In that way, Ueda claims to overcome the prior art dilemma of how to increase conductivity without adverse effect on mechanical properties caused by addition of too large a proportion of conductive particles in the compositions. Otherwise, he is silent as to the amount of powdered mixture to be added to the resin.

Hunter discloses an electrically conductive, heat-producing coating composition made from finely powdered (particle size less than 4 mils) conductive substances, viz., carbon, silver iron, in combination with a flexible resin, wherein the concentration of the powdered conductive component is between 22-53% by volume. It is disclosed as having a resistance sufficient to enable its use as a heating element. Hunter teaches that a mixture of finely powdered carbon, granular silver, and granular iron particles must be used, and that the granule form of metal particles is superior to the flake form. In Example X, Hunter teaches that when the concentration exceeds 53% the coating becomes deficient in mechanical properties such as adherence and flexibility.

Coleman et al. disclose a method of coating copper particles with silver. The particles to be coated may be as large as 40 mils, and Coleman et al. state that such particles may be used in applications calling for electrically-conductive compositions or paints. The disclosure is not limited to any particular particle shape.

Wood discloses a thermally and electrically-conductive sponge rubber composition, used as a heat dissipator or electrostatic shield, in a mounting for electrical components. Particles, preferably in “fine dust” form (no size range is specified), are added to the sponge rubber in an amount determined by the degree of conductivity desired. Wood states that there is “no definite upper limit” to the amount of conductive material which may be added to the rubber and suggests he may use “50% or even more” but discloses no more than 20% by weight of powdered aluminum in any composition which he has “used successfully”

Price discloses the use of substantially spherical particles of gold, silver, copper, or aluminum in combination with flake-type particles of the same materials in conductive resinous coatings. The maximum particle size taught is approximately 44 microns, and Price directs that specified portions of the two different shapes of particles must be used to achieve the desired result.'

McGrath discloses a conductive sealing compound for metal joints which sets or vulcanizes when the surfaces to which it has been applied are heated by spot-welding. The compound is made conductive by inclusion of iron or copper filings, carbon black, and the like. The vulcanized composition forms a substantially gas and liquid-impervious seam or joint.

[905]*905Symposium Digest discloses that silver-coated particles can be added to plastic binders to make gaskets and caulking compounds with good R.F. shielding properties. Only the use of “finely divided” particles (size unspecified) is discussed, and no ingredient portions are given.

The Rejections

35 U.S.C. § 112

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590 F.2d 902, 200 U.S.P.Q. (BNA) 504, 1979 CCPA LEXIS 323, Counsel Stack Legal Research, https://law.counselstack.com/opinion/in-re-ehrreich-ccpa-1979.