Method for producing circuit boards with deposited metal patterns and circuit boards produced thereby

Claim 2

In a process for producing circuit boards having a metallized circuit pattern firmly bonded to a resinous substrate, the steps comprising: (a) coating an initial substrate with a fluid mixture of a formulation containing: (i) a low molecular weight polyfunctional reactive rubber component comprising an interpolymer of butadiene and acrylonitrile; and (ii) an epoxy polymer component, said components being interactive at temperatures of at least l80° F., said rubber component comprising 50-200 percent by weight of the epoxy polymer component, said coating having a thickness of 0.0005-0.015 inch; (b) drying said coating on said initial substrate to produce a transfer coating member, said dried coating exhibiting limited adhesion to said initial substrate; (c) disposing said dried coating of said transfer coating member against a resinous substrate and applying heat to transfer said coating from said initial substrate to said resinous substrate; (d) partially curing the coating to produce partial cross-linking of said epoxy polymer component, further polymerization of the rubber, and interaction of said rubber and epoxy polymer components; (e) etching the exposed surface of the coating to produce a microporous surface; (f) depositing metal on the microporous surface of the coating to form a conductive layer with microformations extending into the recesses of said microporous surface; (g) electrodepositing metal on said conductive layer to form a conductive pattern therewith; and (h) applying heat and pressure to at least said conductive layer and coating to fully cure said coating, thereby firmly bonding said coating to said metal layer and thereby said conductive pattern through said coating to said resinous substrate.

Claim 3

The process in accordance with claim 1 wherein said initial substrate is release paper.

Claim 4

The process in accordance with claim 1 wherein the resinous substrate is preheated to 200°-300° F. before said coating member is disposed thereagainst.

Claim 5

The process in accordance with claim 1 wherein said partial curing step is effected after transfer of the coating to said resinous substrate.

Claim 6

The process in accordance with claim 1 wherein said partial curing step is partially effected on said initial substrate prior to transfer to said resinous substrate.

Claim 7

The process in accordance with claim 1 wherein said step of applying heat and pressure is effected after said step of electrodepositing metal.

Claim 8

The process in accordance with claim 1 wherein said step of applying heat and pressure is effected before said step of electrodepositing metal.

Claim 9

The process in accordance with claim 1 wherein said rubber interpolymer has terminal functional groups selected from vinyl and carboxyl.

Claim 10

The process is accordance with claim 1 wherein said rubber interpolymer has a Brookfield viscosity of 100,000-400,000 cps at 27° C.

Claim 11

The process in accordance with claim 1 wherein said functional terminal groups interact with the epoxy polymer component during curing thereof.

Claim 12

The process in accordance with claim 1 wherein said etching step utilizes a chemical etchant to attack the exposed surface of said coating and produce the microporous characteristic.

Claim 13

The process in accordance with claim 1 wherein said etching step utilizes a plasma to attack the exposed surface of said coating and produce the microporous characteristic.

Claim 14

The process in accordance with claim 1 wherein said metal layer is deposited by a process of vacuum metallizing.

Claim 15

The process in accordance with claim 1 wherein said metal layer is deposited by electroless chemical deposition from a metallic solution.

Claim 16

The process in accordance with claim 1 wherein said terminal functional group is a vinyl group and wherein said rubber component comprises 100-200% by weight of the epoxy prepolymer component.

Claim 17

The process in accordance with claim 1 wherein said step of partially curing the coating comprises developing a temperature of 250°-280° F. in the coating for a period of at least 5 minutes, and wherein said step of fully curing the coating comprises developing a temperature in the coating of 280°-350° F. for a period of at least 2 hours.

Claim 18

The process in accordance with claim 1 wherein said step of applying heat and pressure at least partially embeds said conductive layer in the coating.

Claim 19

The process in accordance with claim 1 wherein a continuous layer of metal is initially deposited on said coating and thereafter selectively etched to remove said layer between said elements of said conductive pattern.

Claim 20

In a process for producing circuit boards having a metallized circuit pattern firmly bonded to a resinous substrate, the steps comprising: (a) coating an initial substrate with a fluid mixture of a formulation containing a rubber component and an epoxy polymer component which are interactive at temperatures of at least 180° F., said rubber component comprising 50-200 percent by weight of the epoxy polymer component, said coating having a thickness of 0.0005-0.015 inch; (b) drying said coating on said initial substrate to produce a transfer coating member, said dried coating exhibiting limited adhesion to said initial substrate; (c) disposing said dried coating of said transfer coating member against a resinous substrate and applying heat to transfer said coating from said initial substrate to said resinous substrate; (d) partially curing the coating to produce partial cross-linking of said epoxy polymer component, and interaction of said rubber and epoxy polymer components to form a matrix of the interacted rubber and epoxy components; (e) etching the exposed surface of the coating to produce a microporous surface; (f) depositing metal on said microporous surface of the coating to form a conductive layer with microformations extending into the recesses of said microporous surface; (g) electrodepositing metal on said conductive layer to form a conductive pattern therewith; and (h) applying heat and pressure to at least said conductive layer and coating to fully cure said coating, thereby firmly bonding said coating to said conductive layer and thereby said conductive layer through said coating to said resinous substrate, said heat and pressure embedding said conductive pattern in said coating to a depth of at least 10 percent of the thickness of the conductive pattern.

Claim 21

In a process for producing circuit boards having a metallized circuit pattern firmly bonded to a resinous substrate, the steps comprising: (a) coating an initial substrate with a fluid mixture of a formulation containing a rubber component and an epoxy polymer component which are interactive at temperatures of at least 180° F., said rubber component comprising 50-200 percent by weight of the epoxy polymer component, said coating having a thickness of 0.0005-0.015 inch; (b) drying said coating on said initial substrate to produce a transfer coating member, said dried coating exhibiting limited adhesion to said initial substrate; (c) disposing said dried coating of said transfer coating member against a resinous substrate and applying heat to transfer said coating from said initial substrate to said resinous substrate; (d) partially curing the coating to produce partial cross-linking of said epoxy polymer component, and interaction of said rubber and epoxy polymer components to form a matrix of the interacted rubber and epoxy components; (e) etching the exposed surface of the coating to produce a microporous surface; (f) depositing metal on said microporous surface of the coating to form a conductive layer with microformations extending into the recesses of said microporous surface; (g) electrodepositing metal on said conductive layer to form a conductive pattern therewith; and (h) applying heat and pressure to at least said conductive layer and coating to fully cure said coating, thereby firmly bonding said coating to said conductive layer and thereby said conductive layer through said coating to said resinous substrate, said heat and pressure embedding said conductive pattern in said coating to a depth of at least 10 percent of the thickness of the conductive pattern.

Claim 22

The process in accordance with claim 19 wherein the resinous substrate is preheated to 200°-300° F. before said coating member is disposed thereagainst.

Claim 23

The process in accordance with claim 19 wherein said rubber component has functional terminal groups which interact with the epoxy prepolymer components during the final curing step.

Claim 24

The process in accordance with claim 19 wherein said etching step utilizes a chemical etchant to attack the exposed surface of said coating and produce the microporous characteristic.

Claim 25

The process in accordance with claim 19 wherein said metal layer is deposited by a process of vacuum metallizing.

Claim 26

The process in accordance with claim 19 wherein said rubber component is a low molecular weight polyfunctional reactive rubber comprising an interpolymer of butadiene and acrylonitrile which is terminated by a functional vinyl group and wherein said rubber component comprises 100-200% by weight of the epoxy polymer component.

Claim 27

The process in accordance with claim 24 wherein said rubber interpolymer has terminal functional groups selected from vinyl and carboxyl.

Claim 28

In a circuit board, the combination comprising: (a) a resinous substrate; (b) an intermediate coating on one surface of said substrate of about 0.0005-0.015 inch and containing a rubber component and an epoxy polymer which have interacted to provide a matrix of the interacted rubber/epoxy polymer, said rubber component comprising at least 35 percent by weight of said coating; and (c) a metal conductive pattern on said coating providing a circuit, said conductive pattern having a base metal layer with microformations at the interface with said coating and extending thereinto, said conductive pattern being embedded in said coating to a depth at least substantially equal to the thickness of said base metal layer, said coating being firmly bonded to said base metal layer and said conductive pattern thereby being bonded through said coating and base metal layer to said substrate, said circuit board being produced by a process comprising the steps of: (i) coating a temporary substrate with a fluid mixture of a formulation containing a rubber component and an epoxy polymer component which are interactive at temperatures of at least 180° F., said rubber component comprising 50-200 percent by weight of the epoxy polymer component, said coating having a thickness of 0.0005-0.015 inch; (ii) drying said coating on said initial substrate to produce a transfer coating member, said dried coating exhibiting limited adhesion to said initial substrate; (iii) disposing said dried coating of said transfer coating member against a resinous substrate and applying heat to transfer said coating from said initial substrate to said resinous substrate; (iv) partially curing the coating to produce partial cross-linking of said epoxy polymer component, and interaction of said rubber and epoxy polymer components to form a matrix of the interacted rubber and epoxy components; (v) etching the exposed surface of the coating to produce a microporous surface; (vi) depositing metal on said microporous surface of the coating to form a conductive layer with microformations extending into the recesses of said microporous surface; (vii) electrodepositing metal on said conductive layer to form a conductive pattern therewith; and (ix) applying heat and pressure to at least said conductive layer and coating to fully cure said coating, thereby firmly bonding said coating to said metal layer and thereby said conductive pattern through said coating to said resinous substrate, said heat and pressure embedding said conductive pattern in said coating to a depth of at least 10 percent of the thickness of the conductive pattern.

Claim 29

In a circuit board, the combination comprising: (a) a resinous substrate; (b) an intermediate coating on one surface of said substrate of about 0.0005-0.015 inch and containing a rubber component and an epoxy polymer which have interacted to provide a matrix of the interacted rubber/epoxy polymer, said rubber component comprising at least 35 percent by weight of said coating; and (c) a metal conductive pattern on said coating providing a circuit, said conductive pattern having a base metal layer with microformations at the interface with said coating and extending thereinto, said conductive pattern being embedded in said coating to a depth at least substantially equal to the thickness of said base metal layer, said coating being firmly bonded to said base metal layer and said conductive pattern thereby being bonded through said coating and base metal layer to said substrate, said circuit board being produced by a process comprising the steps of: (i) coating a temporary substrate with a fluid mixture of a formulation containing a rubber component and an epoxy polymer component which are interactive at temperatures of at least 180° F., said rubber component comprising 50-200 percent by weight of the epoxy polymer component, said coating having a thickness of 0.0005-0.015 inch; (ii) drying said coating on said initial substrate to produce a transfer coating member, said dried coating exhibiting limited adhesion to said initial substrate; (iii) disposing said dried coating of said transfer coating member against a resinous substrate and applying heat to transfer said coating from said initial substrate to said resinous substrate; (iv) partially curing the coating to produce partial cross-linking of said epoxy polymer component, and interaction of said rubber and epoxy polymer components to form a matrix of the interacted rubber and epoxy components; (v) etching the exposed surface of the coating to produce a microporous surface; (vi) depositing metal on said microporous surface of the coating to form a conductive layer with microformations extending into the recesses of said microporous surface; (vii) electrodepositing metal on said conductive layer to form a conductive pattern therewith; and (ix) applying heat and pressure to at least said conductive layer and coating to fully cure said coating, thereby firmly bonding said coating to said metal layer and thereby said conductive pattern through said coating to said resinous substrate, said heat and pressure embedding said conductive pattern in said coating to a depth of at least 10 percent of the thickness of the conductive pattern.

Claim 30

The circuit board of claim 26 wherein said rubber interpolymer has terminal functional groups selected from vinyl and carboxyl.

Claim 31

The circuit board of claim 26 wherein said rubber interpolymer has a Brookfield viscosity of 100,000-400,000 cps at 27° C.

Claim 32

The circuit board of claim 26 wherein said rubber component is a low molecular weight polyfunctional reactive rubber comprising an interpolymer of butadiene and acrylonitrile which is terminated by a functional vinyl group and wherein said rubber component comprises 100-200% by weight of the epoxy polymer component.

Claim 33

The circuit board of Claim 26 wherein said rubber component comprises at least 50 percent by weight of said coating.