Method of improving adhesive properties of a surface comprising a cured epoxy

Claim 2

The method as defined in claim 2 which further comprises: prior to step (c) heating said etched surface to remove residual swellant.

Claim 3

The method as defined in claim 2 which further comprises thermally aging said species-deposited surface.

Claim 4

In an improved method of improving adherence of an electroless metal deposit to a surface of a substrate comprising a cured epoxy product resulting from curing a composition comprising from 0 to 20 weight percent of an uncured epoxylated novolac and a remainder of an uncured bisphenol A-epichlorohydrin epoxy resin, which comprises the steps of: a. sensitizing the surface to form a sensitized surface; b. activating the sensitized surface to form an activated surface; and c. exposing the activated surface to a suitable electroless bath to deposit the electroless metal thereon, the improvement comprising: a1. prior to step (a) above, exposing the cured epoxy surface to a suitable swellant selected from the group of swellants consisting of (1) a mixture comprising 1-methyl-2-pyrrolidinone and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone, anD formic acid, (2) a mixture comprising dimethylformamide and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone, formic acid, 1,1,1 trichloroethane, a mixture comprising methyl ethyl ketone and 1,1,2 trichloro-1,2,2 trifluoroethane and a mixture comprising acetone and 1,1,2 trichloro-1,2,2 trifluoroethane and (3) mixtures thereof, to swell the cured epoxy surface; and b1. prior to step (a) above, exposing said swelled surface at a temperature ranging from 40* to 50* C to an etchant for the cured epoxy surface comprising H2SO4 in a concentration ranging from 2.7 to 5.4 moles/liter of etchant and Cr6, added as CrO3 in a concentration ranging from a minimum of at least 60 grams/liter of etchant solution to saturation of said etchant solution at a particular temperature, to etch said swelled surface.

Claim 5

The method as defined in claim 5 which further comprises heating said etched surface prior to step (a) to remove residual swellant.

Claim 6

The method as defined in claim 5 which further comprises thermally aging said metal-deposited surface.

Claim 7

The method as defined in claim 5 which further comprises treating said etched surface with a suitable Cr 6 removing agent to remove Cr 6 therefrom.

Claim 8

In an improved method of producing an adherent metallic pattern on a surface of a substrate comprising a cured product resulting from curing an uncured epoxy composition comprising from 0 to 20 weight percent of an uncured epoxylated novolac resin and from 100 to 80 weight percent of an uncured bisphenol A-epichlorohydrin epoxy resin, which comprises the steps of: a. coating the surface with a photopromoter; b. producing a pattern capable of reducing a precious metal from a precious metal salt by selectively exposing a portion of the photopromoter-coated surface to a source of short wavelength ultraviolet light; c. immersing the substrate in a precious metal salt solution to reduce on the pattern the precious metal; and then d. placing the precious metal pattern in an electroless plating bath which is catalyzed by the reduced precious metal to produce the metallic pattern, the improvement comprising: a1. prior to step (a) above, exposing the cured epoxy surface to a suitable swelling agent selected from the group of swelling agents consisting of (1) a mixture comprising 1-methyl-2-pyrrolidinone and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone, and formic acid, (2) a mixture comprising dimethylformamide and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone, formic acid, 1,1,1 trichloroethane, a mixture comprising methyl ethyl ketone and 1,1,2 trichloro-1,2,2 trifluoroethane and a mixture comprising acetone and 1,1,2 trichloro-1,2,2 trifluoroethane and (3) mixtures thereof, to swell the cured epoxy surface; and b1. prior to step (a) above, exposing said swelled surface at a temperature ranging from 40* to 50* C to an etchant for the cured epoxy surface comprising H2SO4 in a concentration ranging from 2.7 to 5.4 moles/liter of etchant and Cr 6, added as CrO3 in a concentration ranging from a minimum of at least 60 grams/liter of etchant solution to saturation of said etchant solution at a particular temperature, to etch said swelled surface.

Claim 9

The method as defined in claim 9 which further comprises baking said etched surface prior to step (a) to remove residual swelling agent therefrom.

Claim 10

The method as defined in claim 9 which further comprises thermally aging said metallic patterned surface.

Claim 11

The method as defined in claim 9 which further comprises removing a deposit residing on said etched surface, said deposit being one of the group consisting of said etchant, an etchant-epoxy reaction product and mixtures thereof.

Claim 12

The method as defined in claim 9 which further comprises treating said etched surface with a suitable Cr 6 removing agent to remove Cr 6 ions therefrom.

Claim 13

In an improved method of depositing a metal deposit, having a peel strength of at least 8 lbs./in., on a surface of a substrate comprising a cured epoxy product resulting from curing an uncured epoxy composition comprising from 0 to 20 weight percent of an uncured epoxylated novolac resin and from 100 to 80 weight percent of an uncured bisphenol A-epichlorohydrin resin, which comprises the steps of: a. rendering the surface catalytic with respect to an electroless plating solution; b. exposing the catalytic surface to a suitable electroless bath, catalyzed by the catalytic surface, to deposit the electroless metal thereon; and c. electroplating the electroless metal deposit to obtain a metal deposit having a desired thickness, the improvement comprising: a1. prior to step (a) above, exposing the cured epoxy surface to a suitable swellant, selected from the group consisting of (1) a mixture comprising 1-methyl-2-pyrrolidinone and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone and formic acid, (2) a mixture comprising dimethylformamide and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone, formic acid, 1,1,1 trichloroethane, a mixture comprising methyl ethyl ketone and 1,1,2 trichloro-1,2,2 trifluoroethane, and a mixture comprising acetone and 1,1,2 trichloro-1,2,2 trifluoroethane, and (3) mixtures thereof, for a period of time ranging from 1 to 5 minutes at a temperature of 25* C, to swell the cured epoxy surface; b1. prior to step (a) above, exposing said swelled surface to an etching solution, comprising H2SO4 in a concentration ranging from 2.7 to 5.4 moles/liter of solution and Cr 6, added as CrO3, in a concentration ranging from 60 to 100 grams/liter of solution, at a temperature ranging from 40* to 50* C for a period of time ranging from 1 to 10 minutes, to etch said swelled surface; and c1. thermally aging the metal-deposited surface.

Claim 14

The method as defined in claim 14 which further comprises heating said etched surface prior to step (a).

Claim 15

The method as defined in claim 14 which further comprises treating said etched surface with a suitable Cr 6 removing agent to remove Cr 6 ions therefrom.

Claim 17

The method as defined in claim 17 wherein: in step (b) 60 to 100 grams of CrO3/liter of etching solution was added, and in step (c) said exposure ranged from 1 to 10 minutes at a temperature ranging from 40* to 50* C.

Claim 19

The method as defined in claim 19, wherein in step (c) said surface is heated to a temperature ranging from 100* to 180* C for a time period ranging from 10 minutes to 60 minutes.

Claim 20

The method as defined in claim 19 which further comprises exposing said catalytic surface to an electroless bath, catalyzed by said catalytic surface, to deposit the electroless metal thereon.

Claim 21

The method as defined in claim 19 which further comprises, prior to step (c), treating said etched surface with a suitable Cr 6 removing agent to remove Cr 6 therefrom.

Claim 22

The method as defined in claim 19 which further includes, prior to step (b), preparing said etchant by (1) adding H2SO4 to a water medium to form a first acid solution, (2) adding CrO3 to said first acid solution to form a second acid solution and (3) heating said second acid solution.

Claim 23

The method as defined in claim 21 which further comprises thermally aging said metal-deposited surface.

Claim 25

The method as defined in claim 25 wherein in step (c) said surface is baked at a temperature ranging from 100* to 180* C for a time period ranging from 10 minutes to 60 minutes.

Claim 26

The method as defined in claim 25 which further comprises exposing said catalytic selected portions of said surface to an electroless bath, catalyzed by said catalytic selected portions, to deposit the electroless metal thereon.

Claim 27

The method as defined in claim 25 which further comprises, prior to step (c), removing a deposit residing on said etched surface, said deposit being one of the group consisting of said etchant, an etchant-epoxy reaction product and mixtures thereof.

Claim 28

The method as defined in claim 25 which further comprises treating said etched surface with a suitable Cr 6 removing agent to remove Cr 6 therefrom.

Claim 29

The method as defined in claim 25 which further includes, prior to step (b), preparing said etchant by (1) adding H2SO4 to a water medium to form a first acid solution, (2) adding CrO3 to said first acid solution to form a second acid solution and (3) heating said second acid solution.

Claim 30

The method as defined in claim 27 which further comprises thermally aging said metal-deposited surface.

Claim 31

In an improved method of making a printed circuit board having a metal pattern on a substrate surface comprising a cured epoxy product resulting from curing an uncured epoxy composition comprising from 0 to 20 weight percent of an uncured epoxylated novolac resin and from 100 to 80 weight percent of an uncured bisphenol A-epichlorohydrin resin, which comprises the steps of: a. sensitizing selected portions of the surface corresponding to the metal pattern; b. activating the selected portions; c. exposing the activated selected portions to an electroless bath, to deposit an electroless metal thereon, and d. electroplating the electroless metal deposit to obtain a metal deposit having a desired thickness, the improvement comprising: a1. prior to step (a) above, sweLling the cured epoxy surface with a suitable swellant, selected from the group consisting of (1) a mixture comprising 1-methyl-2-pyrrolidinone and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone and formic acid, (2) a mixture comprising dimethylformamide and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone, formic acid, 1,1,1,1 trichloroethane, a mixture comprising methyl ethyl ketone and 1,1,2 trichloro-1,2,2 trifluoroethane, and a mixture comprising acetone and 1,1,2 trichloro-1,2,2 trifluoroethane, and (3) mixtures thereof; b1. prior to step (a) above, preparing an etching solution by a method comprising (1) adding H2SO4 to water in an amount which gives a concentration ranging from 2.7 to 5.4 moles/liter of solution to form a first acid solution, (2) adding CrO3 to said first acid solution to form a second acid solution, said CrO3 being added in an amount which gives a concentration thereof ranging from 60 to 100 grams/liter of said second acid solution and (3) heating said second acid solution to a temperature ranging from 70* to 80* C for a period of time ranging from 20 to 60 minutes; c1. immersing said swelled surface in said etching solution, maintained at a temperature ranging from 40* to 50* C, for a period of time ranging from 1 to 10 minutes to etch said swelled surface; d1. prior to step (a) above, heating said etched surface to remove residual swellant; and e1. thermally aging the metal-deposited surface.

Claim 32

The method as defined in claim 32 wherein: in step (a1) said swelling is for a period of time ranging from 1 to 5 minutes at a temperature of 25* C.

Claim 33

In an improved method of making a printed circuit board having a metal circuit pattern on a substrate surface comprising a cured epoxy product resulting from curing an uncured epoxy composition comprising from 0 to 20 weight percent of an uncured epoxylated novolac resin and from 100 to 80 weight percent of an uncured bisphenol A-epichlorohydrin resin, which comprises the steps of: a. coating the surface with a photopromoter; b. producing a pattern, corresponding to the metal circuit pattern, capable of reducing a precious metal from a precious metal salt by selectively exposing selected portions of the photopromoter-coated surface to a source of short wavelength ultraviolet radiation; c. immersing the surface in a precious metal salt solution to reduce on the pattern the precious metal; d. placing the precious metal pattern in an eletroless plating bath, which is catalyzed by the reduced precious metal, to deposit electroless metal thereon; and e. electroplating the electroless metal deposit to obtain a metal deposit having a desired thickness, the improvement comprising: a1. prior to step (a) above, swelling the cured epoxy surface with a suitable swellant, selected from the group consisting of (1) a mixture comprising 1-methyl-2-pyrrolidinone and an organic component selected from the group consisting of ethylene glycol, 4-hydroxy-4-methyl-2-pentanone and formic acid, (2) a mixture comprising dimethylformamide and an organic component selected from the group consisting of ethylene gylcol, 4-hydroxy-4-methyl-2-pentanone, formic acid, 1,1,1 trichloroethane, a mixture comprising methyl ethyl ketone and 1,1,2 trichloro-1,2,2 trifluoroethane, and a mixture comprising acetone and 1,1,2 trichloro-1,2,2 trifluoroethane, and (3) mixtures thereof; b1. prior to step (a) above, preparing an etching solution by a method comprising (1) adding H2SO4 to water in an amount which gives a concentration ranging from 2.7 to 5.4 miles/liter of solution to form a first acid solution, (2) adding CrO3 to said first acid solution to form a second acid solution, said CrO3 being added in an amount which gives a concentration thereof ranging from 60 to 100 grams/liter of said second acid solution and (3) heating said second acid solution to a temperature ranging from 70* to 80* C for a period of time ranging from 20 to 60 minutes; c1. immersing said swelled surface in said etching solution, maintained at a temperature ranging from 40* to 50* C, for a period of time ranging from 1 to 10 minutes to etch said swelled surface; d1. prior to step (a) above, heating said etched surface to remove residual swellant; and e1. thermally aging the metal-deposited surface.

Claim 34

The method as defined in claim 34 wherein: in step (a1) said swelling is for a period of time ranging from 1 to 5 minutes at a temperature of 25*C.