Printed circuit board

Claim 1

A method for producing a circuit board having conductive circuit elements with a specific resistivity of less than .05 chm-cm patterned on a nonconductive substrate comprising: a) printing a U.V. curable ink onto the nonconductive substrate in a desired circuit pattern; and b) effecing U.V. radiation cure of the U.V. curable ink by exposing the U.V. curable ink to a U.V. source having an output in the reange of from 360 nm to 420 nm in a pulsing manner comprising 5 to 8 one-half second exposure periods, each exposure period followed by a non-exposure period of about 2 to 3 seconds.

Claim 2

A method for producing a circuit board having conductive circuit elements with a specific resistivity of less than .05 chm-cm patterned on a nonconductive substrate comprising: a) printing a U.V. curable ink onto the nonconductive substrate in a desired circuit pattern; and b) effecing U.V. radiation cure of the U.V. curable ink by exposing the U.V. curable ink to a U.V. source having an output in the reange of from 360 nm to 420 nm in a pulsing manner comprising 5 to 8 one-half second exposure periods, each exposure period followed by a non-exposure period of about 2 to 3 seconds.

Claim 5

A method as claimed in any one of the preceding claims wherein the U.V. curable ink comprises from 30 to 33 weight percent of a thermosetting resin binder and from 70 to 67 weight percent of spherical or spheroidal conductive particles having a particle size distribution in the range of from 1 to 30 micrometres.

Claim 7

A method as claimed in any one of the preceding claims wherein the U.V. curable ink also includes an effective amount of a ketone-amine curing agent, preferably Michler's ketone or a mixture of benzophenone and Michler's ketone.

Claim 16

A method for producing a circuit board having conductive circuit elements with a specific resistivity of less than 0.05 ohm/cm 2 patterned on a non-conductive substrate comprising: a) printing a film of U.V. curable ink onto the non-conductive substrate in a desired circuit pattern, the U.V. curable ink comprising a suspension of a silver-coated magnetite particles in a U.V. curable resin; b) subjecting the resulting printed circuit pattern to a magnetic field sufficient to move the magnetite particles to a position at or near the upper surface of the resin without breaking the surface tension thereof or substantially increasing the thickness of the ink film from the substrate; and c) effecting a U.V. radiation cure of the U.V. curable ink by exposing the U.V curable ink to a U.V. source having an output in the range of from 360 nm to 420 nm for a time sufficient to cure the U.V. curable ink.

Claim 17

A method for producing a circuit board having conductive circuit elements with a specific resistivity of less than 0.05 ohm/cm 2 patterned on a non-conductive substrate comprising: a) printing a film of U.V. curable ink onto the non-conductive substrate in a desired circuit pattern, the U.V. curable ink comprising a suspension of a silver-coated magnetite particles in a U.V. curable resin; b) subjecting the resulting printed circuit pattern to a magnetic field sufficient to move the magnetite particles to a position at or near the upper surface of the resin without breaking the surface tension thereof or substantially increasing the thickness of the ink film from the substrate; and c) effecting a U.V. radiation cure of the U.V. curable ink by exposing the U.V curable ink to a U.V. source having an output in the range of from 360 nm to 420 nm for a time sufficient to cure the U.V. curable ink.

Claim 27

A method of fabricating shielded plastic enclosure for housing electronic equipment comprising applying a layer to at least one interior surface of the enclosure of a shielding composition comprising a suspension of silver-coated magnetite particles in a U.V. curable resin and effecting a U.V. radiation cure of the U.V. curable shielding composition by exposing the U.V. curable shielding composition to a U.V. source having an output in the range of from 360 nm to 420 nm for a time sufficient to cure the U.V curable ink.

Claim 28

A method of fabricating shielded plastic enclosure for housing electronic equipment comprising applying a layer to at least one interior surface of the enclosure of a shielding composition comprising a suspension of silver-coated magnetite particles in a U.V. curable resin and effecting a U.V. radiation cure of the U.V. curable shielding composition by exposing the U.V. curable shielding composition to a U.V. source having an output in the range of from 360 nm to 420 nm for a time sufficient to cure the U.V curable ink.

Claim 31

A method as claimed in any one of claims 21 to 23 wherein the U.V. curable shielding composition contains 25 to 67 percent by volume silver-coated magnetite spheres based on the total volume of the curable shielding composition.