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Low Contact Impedance Shielding Film

IP.com Disclosure Number: IPCOM000073602D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Buschman, RG: AUTHOR [+2]

Abstract

Electrical equipment frames and covers can be coated to impart a low impedance characteristic which is desirable wherever electrical contact is to be made to the part, and particularly where RF shielding is desired.

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This is the abbreviated version, containing approximately 94% of the total text.

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Low Contact Impedance Shielding Film

Electrical equipment frames and covers can be coated to impart a low impedance characteristic which is desirable wherever electrical contact is to be made to the part, and particularly where RF shielding is desired.

An organic material for this purpose is prepared in accordance with the following formula:
(1) MIXING VEHICLE

5.5 oz. by wt. Base Solution (Epoxy Resin Solution)

3.0 oz. by wt. Amido-amine (Polyamide)

.3 oz. by wt. Trimethoxysilylpropylethylenediamine

(Silane)

1.0 oz. by wt. Ethylene glycol monoethyl ether
(2) 1.25 oz. by wt. Mixing Vehicle (shown in (1))

1.5 oz. by wt. Silver Flake

1.5 oz. by wt. Eutectic Powder (97% Tin and 3% Silver)

1.25 oz. by wt. Thinner : 50% by wt. MIBK

25% by wt. Diacetone alcohol

25% by wt. Xylol

The ingredients are mixed together at room temperature and applied, as by spraying or brushing. The resulting film cures at room temperature and, by operation of the silane, is strongly adherent directly to steel or tin without a nonconductive interface coating.

Since no baking is required, the material can be used readily to "touch up" tin plated finished products. However, curing in an oven for up to about 400 degrees F for up to about 20 minutes is desirable when practicable. This step improves the bulk conductivity of the film, apparently by rendering the eutectic plastic temporarily, in which state it contacts the silver flake more intimately.

In either case the use of tin-silver eutectic re...