Adhesive composition comprising maleimide moieties and methods of wet etching

Abstract

A method of wet etching is described comprising providing an article comprising: i) a conductive metallic substrate (221); ii) an insulating resin layer (222); and iii) a cured adhesive layer (230) disposed between the substrate (221) and insulating resin layer (222). The cured adhesive layer (230) comprises the reaction product of at least 50 wt.% of polyimide resin comprising maleimide moieties; at least 0.25 wt.% of amine and / or thiol compound(s), and optionally a free-radical initiator. The method further comprises contacting the article with at least one liquid, wherein the liquid comprises an organic solvent, an alkaline solution, or an acidic solution. The article may be a component of a printed circuit board or integrated circuit comprising (e.g., through) holes and residual insulating resin within the holes. The step of contacting the article with at least one liquid may remove the residual insulating resin from the holes. Also described are articles, methods of making articles, and adhesive compositions.

Description

ADHESIVE COMPOSITION COMPRISING MALEIMIDE MOIETIES AND METHODS OF WET ETCHING

[0001] Summary

[0002] In one embodiment, a method of wet etching is described comprising providing an article comprising: i) a conductive metallic substrate; ii) an insulating resin layer; and iii) a cured adhesive layer disposed between the substrate and insulating resin layer. The cured adhesive layer comprises the reaction product of at least 50 wt.% of polyimide resin comprising maleimide moieties; at least 0.25 wt.% of amine and / or thiol compound(s), and optionally a free-radical initiator. The method further comprises contacting the article with at least one liquid, wherein the liquid comprises an organic solvent, an alkaline solution, or an acidic solution.

[0003] In some embodiments, the article is a component of a printed circuit board or integrated circuit comprising (e.g., through) holes and residual insulating resin within the holes. In some embodiments, the step of contacting the article with at least one liquid removes the residual insulating resin from the holes.

[0004] When the article is subject to wet etching or otherwise exposed to such types of liquids, the cured adhesive layer is resistant to such liquids. In some embodiments, the cured adhesive layer disposed on the conductive metallic substrate has a cross hatch adhesion of at least 2B, 3B, 4B, or 5B before and after contact with at least one of the liquids.

[0005] In another embodiment, a composition is described comprising at least 50 wt.% of polyimide resin comprising maleimide moieties; and at least 0.25 wt.% of amine and / or thiol compound(s). The amine and / or thiol compound(s) are aliphatic, lacking an aromatic group and typically comprising a C4- C60 hydrocarbon moiety. In some embodiments, the backbone of the hydrocarbon moiety is substituted with sulfur or NH. The amine and / or thiol compound(s) that are resistant to liquids of wet etching typically lack ether, carbonyl moieties, and hydroxyl moieties (with the exception of siloxane moieties that condense during curing of the composition). In typical embodiments, the amine or thiol compound(s) comprise at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 7075, 80, 85, or 90 wt.% methylene (CH2) and / or methine (CH). In some embodiments, the amine and / or thiol compound comprises at least one terminal alkoxy silane group and a hydrocarbon moiety with at least four carbon atoms. The composition is suitable for use as an adhesive or a (e.g., protective) coating.

[0006] In another embodiment, an electronic article (e.g., component thereof) is described comprising at least one conductive metallic substrate comprising a cured composition as described herein. In some embodiments, the cured composition is an adhesive that bonds the conductive metallic substrate or metallic layer to an insulating resin layer.

[0007] Also described are methods of making articles.

[0008] Brief Description of the Drawings

[0009] Fig.1 is a cross-section of a two-layer article;

[0010] Fig.2 is a cross-section of a three-layer article; and

[0011] Fig.3 is a cross-section of a portion of an integrated chip 300.

[0012] Detailed Description of the Drawings

[0013] Polyimide with Maleimide Moieties

[0014] The (e.g., adhesive or coating) composition comprises a polyimide comprising maleimide moieties. Polyimides comprise imide groups, -O=C-N-C=O-, in the polymer backbone. The maleimide moieties have the following formula.

[0015] may as a maleimide terminated polyimide. Such a polyimide may have the following Formula 1:

[0016] wherein R1is hydrogen or methyl; and

[0017] and Q and R are independently organic linking groups.

[0018] Q and R are typically independently an aliphatic, cycloaliphatic, alkenyl, aromatic, or heteroaromatic group. Such a group may be substituted or unsubstituted.

[0019] In some embodiments, Q is a (e.g., a tetravalent) aromatic group.

[0020] The maleimide terminated polyimides are derived from the reaction of a diamine with an acid dianhydride. The R group is typically the reaction product of one or more diamines.

[0021] Suitable diamines include for example 4,4'-methylenebis(2,6-diethylaniline); tricyclodecane diamine (TCD-diamine); bisaniline-P; 2.2-bis [4-( 4-aminophenoxy )phenyl] hexafluoropropane; 1, 10- diaminodecane; 1,12-diaminododecane; dimer diamine; hydrogenated dimer diamine; 1,2-diamino-2- methylpropane; 1,2-diaminocyclohexane; 1,2-diaminopropane; 1,3-diaminopropane; 1,4-diaminobutane; 1,5-diaminopentane; 1,7-diaminoheptane;1,8-diaminomenthane; 1,8-diaminooctane; 1,9-diaminononane; 3,3' -diamino-N-methyldipropyl amine; diaminomaleonitrile; 1,3-diaminopentane; 9, 10-diaminophenanthrene; 4,4'-diaminooctafluorobiphenyl; 3,5-diaminobenzoic acid; 3,7-diamino-2- methoxyfluorene; 4,4'-diaminobenzophenone; 3,4-diaminobenzophenone; 3,4-diaminotoluene; 2,6- diaminoanthroquinone; 2,6-diaminotoluene; 2,3-diaminotoluene; 1,8-diaminonaphthalene; 2,4- diaminotoluene; 2,5-diaminotoluene; 1,4-diaminoanthroquinone; 1,5-diaminoanthroquinone; 1,5- diaminonaphthalene; 1,2-diaminoanthroquinone; 2,4-cumenediamine; 1,3-bisaminomethyl benzene; 1,3- bisaminomethylcyclohexane; 2-chloro-1,4-diamino benzene; 1,4-diamino-2,5-dichloro benzene; 1, 4- diamino-2, 5-dimethyl benzene; 4, 4'-diamino-2,2'-bistrifluoromethyl biphenyl; bis( amino-3- chlorophenyl)ethane; bis( 4-amino-3 ,5-dimethylphenyl)methane; bis( 4-amino-3 ,5-diisopropylphenyl)methane; bis( 4-amino-3,5-methyl-isopropylphenyl) methane; bis( 4- amino-3,5-dieth lphenyl)methane; bis( 4-amino-3-ethyl phenyl)methane; diaminofluorene; 4, 4' -(9- fluorenylidene)dianiline; diaminobenzoic acid; 2,3-diaminonaphthalene; 2,3-diaminophenol; -5- methylphenyl)methane; bis( 4-amino-3-methylphenyl)methane; bis( 4-amino-3-ethylphenyl)methane; 4, 4' -diaminopheny lsulfone; 3, 3 ' -diaminophenyl sulfone; 2,2-bis( 4,-( 4-aminophenoxy )phenyl)sulfone; 2,2-bis( 4-(3- aminophenoxy)phenyl)sulfone; 4,4'-oxydianiline; 4,4'-diaminodiphenyl sulfide; 3,4'-oxydianiline; 2,2- bis( 4-(4-aminophenoxy)phenyl)propane; 1 ,3-bis(4-aminophenoxy )benzene; 4,4'-bis( 4- aminophenoxy)bipheny l; 4,4'-diamino-3,3'-dihydroxybiphenyl; 4,4'-diamino-3,3'-dimethylbiphenyl; 4, 4' -diamino-3,3 '-dimethoxy biphenyl; bisaniline M; bisaniline P; 9 ,9-bis( 4-aminophenyl)fluorene; o-tolidine sulfone; methylene bis(anthranilic acid); 1,3-bis( 4- aminophenoxy)-2,2-dimethylpropane; 1,3-bis(4-aminophenoxy propane; 1,4-bis( -aminophenoxy)butane; 1,5-bis(4-aminophenoxy)butane; 2,3,5,6-tetramethyl-l,4-phenylenediamine; 3,3',5,5'-tetramehylbenzidine; 4,4'-diaminobenzanilide; 2,2- bis(4-aminophenyl)hexafluoropropane; polyoxyalkylenediamines; 1,3-cyclohexanebis(methy l amine); mxylylenediamine; p-xylylenediamine; bis( 4-amino-3-methylcyclohexyl)methane; l,2-bis(2- aminoethoxy)ethane; and 3(4),8(9)-bis(aminomethyl)tricyclo(5.2.1.02,6)decane.

[0022] In some embodiments, the diamine is 4,4'-methylenebis(2,6-diethylaniline); bisaniline-P; tricyclodecane diamine (TCD-diamine); 2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane; a fatty (e.g., dimer) diamine such as PRIAMINE™ 1075 or PRIAMINE™ 1074; or a combination thereof.

[0023] In some embodiments, combinations of diamines are utilized. Thus, the polyimide comprises reactions products of at least two different amines. For example, the repeat unit may comprise the reaction product of one diamine and the endcapping group may comprise a different diamine.

[0024] Suitable anhydrides include for example bisphenol-A-dianhydride (e.g., 4,4′-(4,4′- isopropylidenediphenoxy)bis(phthalic anhydride); biphenyl tetracarboxylic dianhydride; pyromellitic dianhydride; maleic anhydride; polybutadiene-graft-maleic anhydride; polyethylene-graft-maleic anhydride; polyethylene- alt-maleic anhydride; polymaleic anhydride-alt-1-octadecene; polypropylene- graft-maleic anhydride; poly(styrene-co-maleic anhydride); maleic anhydride; succinic anhydride; 1,2,3,4- cyclobutene tetracarboxylic dianhydride; 1,4,5,8-naphthalenetetracarboxylic dianhydride; 3,4,9,10- perylenentetracarboxylic dianhydride; bicyclo(2.2.2)oct-7-ene-2,3,5,6-tetracarboxylicdianhydride; diethylenetriaminepentaacetic dianhydride; ethylenediaminetetraacetic dianhydride; 3,3',4,4'- benzophenone tetracarboxylic dianhydride; 3,3',4,4'-biphenyl tetracarboxylic dianhydride; 4,4'- oxydiphthalic anhydride; 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride; 2,2'-bis(3,4- dicarboxyphenyl)hexafluoropropane dianhydride; 4,4'-bisphenol A diphthalic anhydride; 5-(2,5- dioxytetrahydro)-3-methy1-3-cyclohexene-l ,2-dicarboxylic anhydride; ethylene glycol bis(trimellitic anhydride); hydroquinone diphthalic anhydride; allylnadic anhydride; 2-octen-1-ylsuccinic anhydride; phthalic anhydride; 1,2,3,6-tetrahydrophthalic anhydride; 3,4,5,6-tetrahydrophthalic anhydride;1,8- naphthalic anhydride; glutaric anhydride; dodecenylsuccinic anhydride; hexadecenylsuccinic anhydride; hexahydrophthalic anhydride; methylhexahydrophthalic anhydride; and tetradecenylsuccinic anhydride.

[0025] In some embodiments, the anhydride is bisphenol-A-dianhydride; biphenyl tetracarboxylic dianhydride; pyromellitic dianhydride; maleic anhydride; or a combination thereof.

[0026] In some embodiments, combinations of anhydrides are utilized. Thus, the polyimide comprises reactions products of two different anhydrides. For example, the repeat unit may comprise the reaction product of one anhydride and the endcapping group may comprise a maleic anhydride.

[0027] Maleimide terminated polyimides are commercially available. Some representative maleimide terminated polyimides are depicted in WO2021 / 113415; incorporated herein by reference.

[0028] In some embodiments, the (e.g., adhesive or coating) composition comprises a high Tg maleimide terminated polyimide such as depicted by Compounds 1 and 5-7, wherein R comprises an aromatic or cycloaliphatic group. Any one or combination of such compounds may be utilized. In some embodiments, composition can further comprise polyphenylene ether (PPE).

[0029] The glass transition temperature, Tg, of the maleimide terminated polyimides lacking a fatty diamine is typically greater than 170°C, 175°C, 180°C, 195°C, 190°C, 200°C. The Tg is typically no greater than about 210°C. However, the Tg of the composition can be increased by including other (e.g., aromatic) maleimide capped compounds having a high Tg.

[0030] In some embodiments, the (e.g., adhesive or coating) composition comprises a lower Tg maleimide terminated polyimide, such as depicted by Compounds 3 and 8-12, wherein R comprises an aliphatic moiety comprising 4-60 carbon atoms. In this embodiment, the melt temperature of the maleimide terminated polyimide and composition can be less than 100, 90 or 80°C.

[0031] The (e.g., adhesive or coating) composition typically comprises up to 5, 10, 15, 20, 25, or 30 wt.% of moieties comprising an aliphatic moiety comprising 4-60 carbon atoms. When the content is too high, the crosshatch adhesion values to copper can be low. The aliphatic moiety can be saturated, as depicted in the above compounds, or may comprise ethylenic unsaturation. The aliphatic moiety may be linear or branched and may comprise a cycloaliphatic moiety. The aliphatic moiety is typically the reaction product of a fatty acid, fatty acid anhydride, or fatty diamine; including dimers thereof. The aliphatic moiety is typically divalent (e.g., derived from a dianhydride or diamine). In some embodiments, the aliphatic moiety comprises at least 6, 8, 10, 12, 14, 16, 18, 20, 24, or greater than 24 carbon atoms. In some embodiments, the aliphatic moiety comprises less than 60, 50, or 40 carbon atoms. This moiety is typically derived from utilizing a maleimide terminated polyimide, such as depicted by Compounds 3 and 8-12, wherein R comprises an aliphatic moiety comprising 4-60 carbonatoms. However, this moiety can also be derived from use of a maleimide terminated compound with such moiety and / or by use of a diamine with such moiety.

[0032] The physical properties of various maleimide terminated polyimides are reported in literature (e.g., previously cited WO20121113415). The maleimide terminated polyimide typically has a molecular weight of at least 2,000; 4,000, 6,000, 8,000 or 10,000 Daltons. The molecular weight is typically no greater than 25,000 Daltons. In some embodiments, the molecular weight is no greater than 20,000; 15,000; 10,000 or 5,000 Daltons.

[0033] The glass transition temperature, Tg, of the maleimide terminated polyimides comprising fatty diamine moieties is typically less than 170°C, 160, 150, 140, 130, 120°C. The Tg is typically at least 50, 75, or 100°C. Thus, lower concentrations of such moieties is amenable to compositions with higher Tg.

[0034] The Coefficient of Thermal Expansion (CTE) of the cured film of maleimide terminated polyimides can be less than 50 or 25 ppm / °C. The Dielectric Constant (Dk) @20 GHz of the cured film of maleimide terminated polyimides can be less than 2.7, 2.6, 2.5, 2.4, 2.3 or 2.2. The Dissipation Factor (Df) @20 GHz of the cured film can be less than 0.0080, 0.0070, 0.0060, 0.0050, 0.0040, 0.0030, or 0.0020.

[0035] The uncured (e.g., adhesive or coating) composition typically comprises at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 98 wt.% of maleimide terminated polyimide based on the total amount of reactive organic components (i.e. excluding filler). In some embodiments, the composition comprises at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 98 wt.% of maleimide terminated polyimide wherein R comprises an aliphatic moiety comprising 4-60 carbon atoms, such as depicted by Compounds 3 and 8- 12. In some embodiments, the amount of maleimide terminated polyimide is no greater than 99, 95, 90, 85, 80, 75, 70, 65, 60 or 50 wt.% based on the total amount of reactive organic components (i.e. excluding filler).

[0036] In some embodiments, the composition comprises maleimide terminated compounds. In some embodiments, such components comprise at least two maleimide end groups bonded to an aliphatic moiety comprising 4-60 carbon atoms, as described above.

[0037] One representative compound, reported to have a molecular weight of 689 Da and a glass transition temperature of 20°C is depicted as follows:

[0038] Other compounds include:

[0039] Notably the aliphatic moiety of these compounds can be saturated or partially unsaturated as described above.

[0040] Other representative compounds include:

[0041] Other maleimide terminated polyimides are known in the literature, such as described in WO2017 / 002748; incorporated herein by reference.

[0042] When the (e.g., adhesive or coating) composition is subject to wet etching or exposed to acid or alkaline liquids or organic solvents, the maleimide terminated polyimides are preferably free of ether and / or (non-imide) carbonyl moieties.

[0043] However, when the composition is not subject to methods of wet etching or exposure to such liquids, the composition may further comprise ether and / or polyether moieties. Such polyether moieties may be the reaction product of an amine compound, as described in WO2024057206. However, the composition may comprise polyether moieties by utilizing a polyether diamine during the synthesis of the maleimide terminated polyimide. Some representative polyether maleimide compounds are as follows: .(with ether moieties), reported to have a Tg of 229°C is as follows

[0045] Thus, in some embodiments, the (e.g., adhesive or coating) composition may comprise up to 5, 10, or 15 wt.% of polyether moieties, based on the total amount of reactive components. When low Dk and Df values are desired the total amount of polyether moieties is typically no greater than 5, 4, or 3 wt.% of the composition. When the amount of polyether is too high, the Dk and Df values can increase.

[0046] Amine and Thiol Compounds

[0047] As illustrated by the forthcoming examples, adhesive and coating compositions comprising amine and / or thiol compound(s) thereof can provide good initial adhesion to conductive metallic substrates, such as copper. It is appreciated that these compounds can also react with the maleimide moieties and other optional components of the composition. Thus, the cured composition may comprise unreacted amine and / or thiol compound(s) as well as reaction products thereof. The composition also has good adhesion to insulating resin layers such an epoxy resin. Further, in some embodiments the composition is resistant to wet etching and thus also provides good adhesion between the conductive metallic substrate and insulating layer during and after wet etching.

[0048] Amine compounds comprise at least one amine group and more typically two or more amine groups. The amine compound may comprise amine groups that include a primary amine, a secondary amine, a tertiary amine, or a combination thereof. The amine compounds are preferably aliphatic since aromatic amines can increase the Dk. In some embodiments, the amine compound comprises at least 3, 4, 5, or 6 amine groups. In some embodiments, the amine compound comprises no greater than 6, 5, 4, 3, or 2 amine groups.

[0049] Thiol compounds comprise at least one thiol group and more typically two or more thiol groups. The thiol compound is also preferably aliphatic. In some embodiments, the thiol compound comprises at least 3, 4, 5, or 6 thiol groups. In some embodiments, the thiol compound comprises no greater than 6, 5, 4, 3, or 2 thiol groups.

[0050] The amine and / or thiol compound(s) is preferably aliphatic, lacking an aromatic moiety. The amine and / or thiol compound(s) typically comprises an aliphatic (e.g., hydrocarbon) moiety comprising 4-60 carbon atoms. The aliphatic (e.g., hydrocarbon) moiety of the amine and / or thiol compounds(s) can be alkyl, alkylene, alkene, alkyne, or combinations thereof. In some embodiments, the hydrocarbon moiety comprises at least 6 or 8 carbon atoms. In some embodiments, the hydrocarbon moiety comprises no greater than 50, 40, 30, or 24 carbon atoms. In some embodiments, the hydrocarbon moiety comprises no greater than 22, 20, 18, 16, 14, or 12 carbon atoms. The aliphatic (e.g., hydrocarbon) moiety of theamine and / or thiol compounds(s)may be straight-chained, branched, and may comprise cycloaliphatic groups. In some embodiments, the compound comprises a single aliphatic moiety (e.g., hydrocarbon chain). In other embodiments, the compound comprises at least two, three, or four aliphatic moieties (e.g., hydrocarbon chains).

[0051] The amine and / or thiol compound(s) comprise at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 75, 80, 85, or 90 wt.% methylene (CH2) and / or methine (CH). In some embodiments, the amine and / or thiol compound(s) comprise no greater than 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 30, 25 wt.% methylene (CH2) and / or methine (CH). Various compounds can be defined by a range formed by a minimum and maximum wt.% methylene (CH2) and / or methine (CH), as just described.

[0052] Examples of amines comprising more than one aliphatic moieties (e.g., hydrocarbon chains) include fatty diamines such as PRIAMINE™ 1071, PRIAMINE™ 1075 or PRIAMINE™ 1074. The structure of the fatty dimer diamine is as follows: .

[0053] 1075 comprises greater than 99% dimer diamine. Notably, such fatty dimer diamines are highly compatible with polyimide resin comprising maleimide moieties prepared from these same diamines.

[0054] In some embodiments, the (e.g., adhesive or coating) composition (e.g., suitable for wet etching) comprises the fatty diamine compound, as just described. In other embodiments, the composition utilizes other amine and / or thiol compounds and thus lacks the fatty diamine just described. In yet other embodiments, the composition may comprise a combination of compounds wherein a first compound comprises the fatty diamine, as just described and the second compound is a different amine and / or thiol compound as described herein.

[0055] In some embodiments, the amine compound comprises a cycloaliphatic moiety. Representative amine compounds include, for example, 4,4'-methylenebiscyclohexylamine, isophorone diamine, and the PRIAMINE fatty diamines just described.

[0056] In some embodiments, the amine an / or thiol compound comprises a hydrocarbon moiety wherein carbon atoms of the hydrocarbon moiety are substituted with sulfur or -NH. Representative compounds include, for example, N-3-trimethoxysilylpropyldiethylene triamine and 2,3-bis-2-mercaptoethylthio-1- propanethiol.

[0057] In some embodiments, the amine and / or thiol compound comprises at least one amine or thiol group and at least one terminal alkoxy silane group. Such compound typically comprises a hydrocarbon moiety with at least 4, 5, 6, 7, or 8 carbon atoms. The at least one amine or thiol group can react with the polyimide (e.g., maleimide moieties). The alkoxy silane group can form a covalent bond with siliceous (e.g., filler) components of the composition or insulating layer. Representative compound of this typeinclude, for example, trimethoxysilyloctyldiamine, aminobutyltriethoxysilane, aminoundecyltriethoxysilane, N-3-trimethoxy-silylpropyldiethylene triamine, 3- mercaptopropyltrimethoxysilane and 3-mercaptooctyltrimethoxysilane.

[0058] Although polyether amine compounds, such as described in WO2024057206 can improve adhesion to metallic substrates, such as copper, it has been found that such compounds are not resistant to wet etching. Thus, when the composition, electronic article or component thereof is subject to wet etching or exposure to organic solvent, acids, or bases; the amine and / or thiol compound lacks oxygen substituents, such as ether, other carbonyl that is not an imide (e.g., ester), and hydroxyl moieties.

[0059] The (e.g., adhesive or coating) composition comprises an amine and / or thiol compounds(s) in an amount of at least 0.25, 0.5, 1, 2, 3, 4, or 5 wt.% based on the total amount of reactive components. In some embodiments, the composition comprises no greater than 15 or 10 wt.% of amine and / or thiol compound(s). In some embodiments, the composition comprises less than 10, 9, 8, 7, 6, 5, 4, or 3 wt.% of amine and / or thiol compounds(s). A single curing compound or combinations of two or more compounds can be utilized. Such combinations can include two or more amine compounds, two or more thiol compounds, or at least one amine compound and at least one thiol compound. Typically the minimum amount of compound that can provide the desired cross hatch adhesion is utilized. The preferred amount of amine and / or thiol compounds(s) can vary depending on the compound(s) utilized.

[0060] In some embodiments, the amine and / or thiol compound(s) or reaction product thereof may be uniformly distributed within the adhesive or coating layer.

[0061] In other embodiments, the amine and / or thiol compound(s) or reaction product thereof is concentrated at an interface with the conductive metallic substrate or an interface with the insulating resin layer, or a combination thereof.

[0062] Additional Components

[0063] The (e.g., adhesive or coating) composition may further comprise other components including for example a thermal initiator, an oligomer (e.g., polyimide oligomer), inorganic filler, epoxy resin, reactive diluent, oxidizing agent, and combinations thereof.

[0064] The (e.g., adhesive or coating) composition is typically a one-part composition comprising all the requisite and optional components combined with each other. However, it is also contemplated that some of the components may be added immediately prior to use. For example, the composition may have a longer shelf life when the amine compound and / or thermal initiator are added immediately prior to use. It is also contemplated that the composition is a two-part composition wherein the combination of first and second part comprises all the requisite and optional components. For example, the first part may be applied to the conductive metallic substrate and the second part applied to the insulating resin layer. In these embodiments, the first and second part are combined during manufacture of the article.

[0065] The (e.g., adhesive or coating) composition typically comprises a thermal free radical initiator such as an organoperoxide. Representative compounds include dialkyl peroxides and dicumyl peroxide available under the trade designation LUPEROX from Arkema.

[0066] In typical embodiments, the (e.g., adhesive or coating) composition may lack triazine compound curatives. In this embodiment, a bismaleimide-triazine (BT) resin is not formed.

[0067] The (e.g., adhesive or coating) composition may optionally comprise an epoxy resin. Various aromatic and aliphatic epoxy resins are known in the art. When present, the amount of epoxy resin is less than the amount of polyimide. Thus, the epoxy resin can be present in an amount less than 50, 40, 30, wt.% of the reactive components. In some embodiments, the composition comprises less than 25, 15, 10, 5, 4, 3, 2, 1, 0.5, or zero epoxy resin. Small amounts of epoxy resin may be beneficial to adjust the properties or co-cure with the B-stage epoxy pre-preg. In such embodiments, the amount of epoxy resin is typically at least 1, 2, 3, 4, 5, 10, 15, or 20 wt.% of the reactive components.

[0068] The (e.g., adhesive or coating) composition optionally comprises a reactive diluent. Representative reactive diluents include for example acrylates, methacrylates, styrenics, isopropenylbenzene derivatives, acrylamides, methacrylamides, maleates, cinnamates, vinyl pyridine; aldehydes; episulfides, cyclosiloxanes, oxetanes, lactones, acrylonitrile, cyanoacrylates, vinyl ketones, acrolein, vinyl sulfones, vinyl sulfoxides, vinyl silanes, glycidol, isocyanates and combinations thereof. The amount of reactive diluent can range from 0 to 30 wt.% of the reactive components. Minimizing the reactive diluent can maximize the concentration of polyimide, which in turn can contribute to the adhesive having suitable dielectric properties.

[0069] However, when the composition, electronic article or component thereof is subject to wet etching or exposure to organic solvent, acids, or bases; the composition may lack oxidizing agent, (meth)acrylate, (meth)acrylamide, lactone and triazine curatives.

[0070] In some embodiments, the (e.g., adhesive or coating) composition comprises inorganic filler including for example siliceous filler (e.g., fumed and / or fused silica), alumina, titanium dioxide, calcium carbonate, graphite, boron nitride, fluoropolymers such as polytetrafluoro- ethylene, and mixtures thereof. In some embodiments, the composition lacks fluorinated resins and fillers. When present, the amount of (e.g., inorganic) filler is typically at least 5, 10, 15, 20, 25, or 30 wt.% of the total composition. The amount of (e.g., inorganic) filler is typically less than 50, 45, 40, 35, or 30 wt.% of the total composition. The inclusion of (e.g., silica) filler can be amenable to reducing the dielectric constant, but when the concentration is too high it can be detrimental to adhesion.

[0071] The filler may optionally comprise a silane coupling agent . For example, it is common to apply a silane coupling agent to an inorganic filler as a surface treatment. Various silane coupling agents are known including amino silanes and epoxy silane. In some embodiments, the amino silanes typically comprise an alkylene moiety with no greater than 3 carbon atoms. In other embodiments, the amino silane comprises an alkylene moiety with at least 4, 5, 6, 7, or 8 carbons atoms. In this embodiment, the same class of amino silanes can be utilized as both an adhesion promoting agent and as a surface treatment for an inorganic (e.g., siliceous) filler.

[0072] Methods of Making Articles and Component Thereof

[0073] In one embodiment, the method of making an (e.g., electronic component) comprises providing a conductive metallic substrate; applying the (e,g., adhesive or coating) composition as described herein to the conductive metallic substrate; and curing the composition.

[0074] The adhesive composition can be used in various methods of bonding. The method generally comprises providing a first substrate, such as a conductive metallic substrate. The method further comprising providing a second substrate or layer, such as an insulating resin layer. The method further comprises providing an adhesive layer, as described herein, between the first substrate and second substrate or layer.

[0075] In some embodiments, a single layer of the adhesive is applied to the first (e.g., conductive metallic) substrate. In other embodiments, a single layer of the adhesive is applied to the second substrate (e.g., insulating resin layer). Although it is convenient to apply a single layer of adhesive, wherein the adhesive comprises all the requisite components, two-part or multiple layers of the adhesive composition are also contemplated. For example, an adhesive precursor comprising the amine compound may be applied to the first (e.g., conductive metallic) substrate and an adhesive precursor comprising the polyimide with maleimide moieties applied to the second substrate (e.g., insulating resin layer). The adhesive composition comprising both components is formed by contacting the adhesive precursors with each other.

[0076] In some embodiments, the polyimide with maleimide moieties, amine compound, and other components of the composition are dissolved in a solvent such as a hydrocarbon solvent, an ester, an ether, or a ketone solvent. In some embodiments, the components are dissolved in a mixture of two or more solvents. The hydrocarbon solvent can be pentane, hexane, heptane, cyclohexane, benzene, toluene, xylene, petroleum ether, or kerosene. The ester solvent can be methyl acetate, ethyl acetate, propyl acetate or butyl acetate. The ketone solvent can be acetone, methyl ethyl ketone, methyl propyl ketone, 3- pentanone, cyclopentanone, or cyclohexanone. The ether solvent can be diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1,2-dimethoxy ethane, or tetrahydropyran. In some embodiments, the solvent is a cyclic molecule containing at least one oxygen atom. This solvent-based (e.g., adhesive or coating) composition can be applied to a substrate or substrates.

[0077] In one embodiment, the composition in solvent may be applied (e.g., doctor bladed) onto a continuous moving substrate (e.g., thin copper sheet or prepreg) on a (e.g., heated) conveyor belt. On a continuous line, a second substrate (e.g., sheet of copper or prepreg) is applied on top of the adhesive composition followed by lamination between hot rollers to form a 3-layer laminate.

[0078] The prepreg typically comprises a fibrous material impregnated with epoxy resin. The fibrous material may be woven or nonwoven. The fibrous material typically comprises organic fibers such as polyimide fiber, polyaramide fiber, polyester fiber, and / or inorganic fibers such as glass fiber, carbon fiber, or other inorganic fibers. The fibrous material may have a thickness of at least 5 or 10 microns. This thickness is typically no greater than 100 or 50 microns.

[0079] Various insulating layers have been described in the literature. Insulating resin layers typically comprises at least 40, 50, 60 or 70 wt.% of inorganic filler including siliceous filler, fused silica, and boron nitride. In some embodiments, the insulting layer comprises an epoxy resin.

[0080] Various insulating layers, including those made from epoxy resin are known. See for example US 10,501,620; incorporated here by reference.

[0081] Various epoxy resins are known such as a cresol novolac type epoxy compound, phenol novolac type epoxy compound, aliphatic chain epoxy compound, glycidyl ester type epoxy compound, glycidyl amine type epoxy compound, biphenyl type epoxy compound, and epoxy-modified rubber.

[0082] In some embodiments, the epoxy resin comprises a bisphenol type epoxy compound, i.e. an epoxy derived from bisphenol, such as bisphenol A, bisphenol F, bisphenol AF, bisphenol S, bisphenol M, bisphenol E, bisphenol P, bisphenol AP, and bisphenol Z, etc. Depending on what compound is reacted with the hydroxy group of the bisphenol, the bisphenol type epoxy compound can include various divalent linking groups between the oxygen atom of the former -OH group and the epoxy group.

[0083] In some embodiments, the epoxy resin may comprise one or more cycloaliphatic groups. In some embodiments, the epoxy resin may comprise two or more (e.g., fused) cycloaliphatic groups such as norbornane, norbornene, norbornadiene, dicyclopentadiene, adamantane, or dicyclopentadiene.

[0084] In other embodiments, the solvent-based adhesive composition can also be coated onto a release (e.g., PET) film, dried, and wound into rolls forming a transfer tape / film. The rolls of polyimide are then cut to size and sandwiched between (e.g., copper foil) substrates or between a first (e.g., copper foil) and second different (e.g., insulating) layer. The polyimide film can be laminated onto the substrate with heat and / or pressure.

[0085] The (e.g., adhesive or coating) composition can be thermally cured at temperatures up to about 170oC. The heat causes polymerization of the maleimide moieties with each other and crosslinking of the maleimide moieties with the amine compound. Other reactions may also occur.

[0086] Articles and Components Thereof

[0087] Various articles can be formed from the (e.g., adhesive or coating) composition including printed circuit board and integrated circuit of electronic articles and intermediate components thereof. Illustrative electronic articles include for examples a mobile phone, PHS, laptop PCs, PDAs (personal digital assistants), mobile TV phones, PCs, super computers, servers, routers, liquid crystal projectors, engineering work stations (EWS), pagers, word processors, televisions, viewfinder type or monitor direct viewing type video tape recorders, electronic handheld devices, electronic desktop computers, car navigation systems, POS terminals, devices provided with touch panels, and other various electronic equipment.

[0088] With reference to FIG.1, various two-layer articles 100 can be formed. Such two-layer articles generally comprise a layer of the (e.g., adhesive or coating) composition 130, as described herein, disposed on a substrate 120.

[0089] The (e.g., adhesive or coating) composition layer typically has a thickness of at least 0.25, 0.5, 1, 1.5, or 2 microns. In some embodiments, the composition has a thickness no greater than 100, 50 or 25 microns.

[0090] In some embodiments, the substrate is a (e.g., PET) release liner. In this embodiment, the article may be a transfer tape or transfer film. In other embodiments, the substrate is a conductive metallic substrate (e.g., copper) or an insulating layer, such as an epoxy prepreg. In these embodiments, the articles may be components of an electronic article.

[0091] With reference to FIG.2, various three-layer articles 200 can be formed generally comprising the adhesive layer 230 disposed between a first 221 and second substrate or layer 222.

[0092] The presently described adhesive compositions are suitable for bonding to substrates such a metal (e.g., copper) and suitable for bonding to (e.g., epoxy resin) insulating layers. Bonding to such substrates is of importance for the manufacture of electronic telecommunication articles. As used herein, electronic refers to devices using the electromagnetic spectrum (e.g., electrons, photons); whereas telecommunication is the transmission of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio, optical or other electromagnetic systems. Electronic telecommunication articles include for example copper-clad laminates, printed circuit boards, integrated circuits, antennas, and optical cables.

[0093] The adhesive composition and transfer tape film are particularly useful for bonding to metals, such as copper, for use for copper-clad laminates, printed circuit boards (PCBs), and bonding packaged integrated circuits to a PCB.

[0094] In some embodiments, the metallic substrate (e.g., copper) has a surface roughness (Ra or Rz) of less than 10 or 5 microns. In some embodiments, the metallic substrate (e.g., copper) has a surface roughness (Ra) of less than 2, 1, 0.5, 0.1, or 0.01 microns. The (e.g., adhesive or coating) may be suitable for bonding metallic substrate (e.g., copper) having an even lower surface roughness (e.g., less than 0.001. Copper having a roughness of 0.15 nm to 1.1 nm has been described in the literature. As the surface roughness decreases, the surface is more difficult to bond to. However, the composition can also be utilized with metallic substrates having a greater surface roughness.

[0095] A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from (e.g., copper) metal sheets laminated onto a non-conductive substrate. Such boards are typically made from an insulating layer such as glass fiber reinforced (fiberglass) epoxy resin or paper-reinforced phenolic resin. The pathways for electricity are typically made from a negative photoresist. An insulating layer is disposed on the surface of the (e.g., copper) metal substrate. Portions of insulating layer are removed to form the conductive (e.g., copper) pathways. The insulting layer (e.g., photoresist) remains present, disposed between the conductive (e.g., copper) pathways of the printed circuit board. Solder is used to mount components on the surface of these boards.

[0096] Numerous PCB and IC constructions are described in the literature.

[0097] One illustrative cross-section of a portion of an integrated chip 300 is depicted in Fig.3.

[0098] In this embodiment, an adhesive layer 330 is being utilized to bond smooth copper to a first insulating layer 323, e.g., an epoxy (e.g., build up) material. Such epoxy build up material comprises high concentration of silica and thus is difficult to bond to. The opposing surface of the copper may be bonded to a second insulting layer 324, such as an epoxy or polyimide prepeg. The adhesive may also be used to bond the copper to this second insulting layer.

[0099] Prior to (e.g., thermal) curing the adhesive can sufficiently flow and fill around copper traces up to an order of about 2 microns. After (e.g., thermal) curing, the adhesive layer can be removed along with the insulating layer using various patterning techniques including laser ablation, wet etching, dry etching, and electroless copper reception. Before and after (e.g., thermal) curing the adhesive can have high bond strength to copper and (e.g., filled) epoxy substrate.

[0100] Methods of Wet Etching

[0101] To make electrical connections between two or more circuit layers on opposite sides of a (e.g., double-sided) circuit board, “through holes” are formed through the two conducting circuit layers and the insulator board. In some embodiments, the through holes are at least 0.025 or 0.05 mm and often no greater than 5 or 6 mm. Multilayer circuit boards also use holes to complete circuits between opposite sides of the insulating layer, as well as intermediate layers. When intermediate conductive layers are electrically connected the holes do not extend through the entire circuit board, yet may still be characterized as “through holes” since the holes extend through a portion of the layers. The through holes can be formed by chemical treatment such as photolithography or by physical treatment such as drilling, laser irradiation, and plasma etching.

[0102] In some embodiments, the insulating layer further comprises a second cured adhesive layer on the opposite planar surface as the i) conductive metallic substrate. In other words the adhesive composition described herein is applied to both major surfaces of the insulating layer and cured. In this embodiment, the cured adhesive layer can protect the insulating layer from exposure to the liquid(s) during wet etching.

[0103] When a through hole is formed, a residue (also referred to as a “smear”) of insulating material remains on the exposed (inside surfaces) of the hole, including the conductive surface within the hole. As used herein, “residue” refers to a small amount of something that remains (after the main part has gone or been taken or used). This residue is removed prior to positioning or depositing the conductive material in the through hole. In typical embodiments, the residue is removed by wet etching (“wet desmear”). Such method involves contacting at least the residual insulating material of the article with at least one liquid. Common liquids include liquids comprising an organic solvent, alkaline liquids, or acidic liquids. One common method includes three chemical steps. In the first step, an organic solvent is applied to soften the residual insulating material. In the second step, a permanganate compound or other oxidizing agent is applied to remove the swelled resin. In a third step, a neutralizer (also described as a “reducer”) is applied to neutralize and remove the permanganate from the resin surface. Rinsing steps carried out by flooding, dipping, or spraying are often conducted between each step. Further, the steps may be conducted at temperatures greater than room temperature. For example, one or more stepsmay be conducted at a temperature of at least 30, 40, 50, 60, 70, or 80°C. The process steps may beperformed with conveyor equipment a n d / o r dip tanks as known in the art.

[0104] Various aqueous solutions comprising organic solvents, (e.g., permanganate) oxidizers and (e.g., acidic) neutralizers are described in the art. See for example, US 6,454,868; incorporated herein by reference; as well as the three chemical steps of the forthcoming examples.

[0105] Common organic solvents for softening the residual insulating material include for example propylene glycol ethers, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and tripropylene glycol methyl ether. In some embodiments, a mixture of at least two organic solvents may be utilized. The first solvent may be gamma-butyrolactone, ethyl-3-ethoxy-propionate, N-ethyl-2- pyrrolidone, N-(2-hydroxyethyl)-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-octyl-2-pyrrolidone, and mixtures thereof. The second organic solvent may be N-methyl-2-pyrrolidone, 2-pyrrolidone, tetrahydrofuran, N-ethy1-2-pyrrolidine, N-cyclohexyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, and mixtures thereof. Surfactants, including fluorochemical surfactants may be included with the organic solvent(s). Permanganate oxidizers include alkaline solutions of sodium, potassium or lithium permanganate. Neutralizers include oxalic acid or aqueous acidic solutions such as dilute sulfuric acid, hydrochloric acid, acidified stannous chloride, hydroxylamine hydrochloride, or formaldehyde.

[0106] When an insulating layer is bonded to a conductive metallic substrate or layer with an adhesive as described herein, the adhesive needs to be resistant to the wet etching process. As evident by the forthcoming examples, the cured adhesive layer disposed on a conductive metallic substrate(s) has a cross hatch adhesion of at least 2B, 3B, 4B, or 5B before and after contact with at least one, two, or all three the wet etching liquids.

[0107] It is appreciated that since the composition described herein has been found to be resistant to all three of these steps, the composition is also resistant to methods that comprise any one of these steps or combination of two steps without the third step. Thus, the composition is resistant to organic solvents, such as those previously described. The composition is also resistant to alkaline liquids. Alkaline liquids have a pH greater than 7, such as a pH of at least 8, 9, 10, 11, or 12. The composition is also resistant to acidic liquids. Acidic liquids have a pH of less than 7, such as a pH of no greater than 6, 5, 4, 3, or 2. The composition is also water resistant (i.e., neutral pH).

[0108] After the insulating resin residue is removed (e.g., desmeared), the inside wall surfaces of the holes are filled with conductor material. In some embodiments, a second metallic layer is formed on the insulating layer concurrently with filling the desmeared holes. When the cured adhesive layer is disposed on both sides of the insulating layer, the method may further comprise applying a second conductive metallic layer to the second cured adhesive layer by electroless plating, electrolytic plating, or a combination thereof.

[0109] EXAMPLES

[0110] Unless otherwise noted or apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Table 1, below, lists materials used in the examples and their sources. Table 1 Material Abbreviation Description and Vendor Name 1,1-Bis(tert-butylperoxy)-3,3,5- Supplied by Arkema (Colombes, France) as L231 trimethylcyclohexane Luperox® 231 Imide extended bismaleimide Supplied by Designer Molecules, Inc. (San Diego, BMI-2500 oligomer CA, USA) as BMI-2500 Bismaleimide resin BMI-689 Supplied by Designer Molecules, Inc. as BMI-689 Amines Suitable for Wet Etch Resistance Supplied by Cargill (Wayzata, MN, USA) as Dimer diamine P1075 Priamine 1075 (high purity grade, amine value 205 mgKOH / g) Supplied by Cargill as Priamine 1071 (regular Dimer diamine P1071 grade, amine value 205 mgKOH / g) 4,4'- Methylenebiscyclohexylamine Supplied by BASF as Baxxodur® EC 330 MBCHA Isophorone diamine IPDA Supplied by BASF as Baxxodur® EC 201 Trimethoxysilyloctyldiamine Supplied by ShinEtsu (Tokyo, Japan) as KBM- TMSODA 6803 N-3- Trimethoxysilylpropyldiethylene triamine Supplied by Millipore-Sigma (Burlington, MA, TMSPDTA USA) as 413348 Comparative Amines Trifunctional polyetheramine Supplied by BASF (Florham Park, NJ, USA) as T403 T403 Baxxodur® EC 310Difunctional polyetheramine D230 D230 Supplied by BASF as Baxxodur® EC 301 3-Aminopropyltrimethoxysilane APTMS Supplied by Millipore-Sigma as 281778 Reactants Supplied by Millipore-Sigma (Burlington, MA, Cysteamine -- USA) as 30070 Diethyloxalate -- Supplied by Millipore-Sigma as 135364 Supplied by Alfa Aesar (Haverhill, MA, US) as 1-Hexene -- B20271 Thiols Suitable for Wet Etch Resistance 2,3-Bis-2-mercaptoethylthio-1- propanethiol Supplied by Bruno Bock GmbH (Marschact, DMPT Germany) as Thiocure DMPT 3- Mercaptooctyltrimethoxysilane Supplied by ShinEtsu (Tokyo, Japan) as KBM- MOTMS 8803 Comparative Thiols Dithiol oxamide M1 Synthesized as described below Thioether of DMPT M2 Synthesized as described below Pentaerythritol terakis(3- PETMP Supplied by Millipore-Sigma as 381462 MercaptopropionateBis(3- Supplied by Gelest (Morrisville, PA, US) as triethoxysilylpropyldisulfide BTESPDS SIB1824.6 3- Mercaptopropyltrimethoxysilane MPTMS Supplied by Alfa Aesar as B23726 2,4,6-Trimethylbenzoylphenyl- TPOL Supplied by BASF as TPO-L phosphinic acid ethyl ester Wet etch solutions NA Supplied by Atotech (Berlin, Germany) as Securiganth^MV Sweller, P-Etch and Reduction Conditioner concentrates

[0111] Synthesis of Dithiol Oxamide (M1)

[0112] A solution of cysteamine (3.08 g, 0.04 mol) in ethanol (20 mL) was cooled to 5^C in an ice bath. Diethyloxalate (2.92 g, 0.02 mol) was added dropwise with stirring, with the formation of a white precipitate. The mixture was heated at 60 ^C for 1 hr. The white precipitate was isolated by filtration (Whatman 4 paper), washed (3 x 20 mL ethanol) and dried (80 ^C / 1 hr). 1H NMR (CD3OD / 1 drop d7- DMF) showed loss of diethyloxalate methyl and methylene (1.3 and 4.3 ppm), and appearance two product methylenes (2.7 and 3.4 ppm).

[0113] Synthesis of

[0114] A mixture of DMPT (2.27g, 8.71 mmol), 1-hexene (2.19 g, 0.026 mol, 3 equiv.) and TPO-L (0.04g, 1 wt% relative to reagents) was stirred while exposed to UV (Clearstone CF1000 UV LED system, 395 nm, 100% intensity corresponding to 319 mW / cm2for 15 minutes at a distance of 10 cm from the flask). Excess hexene was removed in vacuo to give the product as a pale yellow odorless oil. The oil was dissolved in chloroform and a fine white precipitate of unreacted cysteamine was removed by filtration. Chloroform was removed in vacuo to isolate the target product as a viscous colorless oil.1H NMR (CDCl3) showed loss of the alkene-adjacent methylene in 1-hexene (2.00 ppm) and theof new methylene peaks (1.35, 1.55 and 2.50 ppm). (R = n-Hexyl)

[0115] Nuclear Magnetic Resonance (NMR) Spectroscopy

[0116] NMR samples were analyzed as solutions in deuterated chloroform. NMR spectroscopy was conducted using a Bruker AVANCE III 500 MHz NMR spectrometer equipped with a CPBBO gradient cryoprobe, a Bruker B-ACS 60 autosampler, and Bruker Topspin 3.04 software. Spectra were analyzed using Advanced Chemistry Development software (Toronto, Canada). Analysis of the chemical shifts and integrals in the proton spectra confirmed the formation of the target products.

[0117] Coating of Bonding Film Compositions Table. Components (pph) BMI-2500 BMI-689 L231 1,3-Dioxolane 26.91 2.99 0.302 69.80

[0118] BMI-2500 was formulated with BMI-689 at a ratio of 90 to 10, dissolved in 1,3-dioxalane at 30 wt,% solids, and peroxide initiator Luperox 231 was used at 1 wt.% relative to total solids. Various (amine or thiol) adhesion promoters were added and dissolved in this base formulation at a loading of 2 wt,% relative to total solids (unless otherwise specified). Smooth electro-deposited copper was obtained and its surface was washed with isopropyl alcohol (IPA). The copper substrate was used immediately. Its surface roughness was measured to be Ra 0.01. 0.5 mL of formulation was pipetted onto the copper substrate and allowed to spread into a circle ~2 cm in diameter. The coated sheets of copper were heated at 40 ^C for 30 mins (slow solvent removal step), and then heated at 130 ^C for 30 mins followed by 170 ^C for 30 mins (curing step). Cures were performed in a solvent-rated air oven.

[0119] Crosshatch Adhesion & Wet Etch

[0120] Crosshatch adhesion tests on cured samples were performed as described in ASTM D3359-09 (Standard Test Methods for Measuring Adhesion by Tape Test) where a grid of 25 squares is cut, tape and pressure via roller are applied on top of the grid, the construction is left to dwell for two mins, the tape is peeled off, and the state of the grid and the residue on the tape are inspected. A crosshatch value of 0B denotes poor adhesion (greater than 65% of grid area detached upon tape removal) through a range of 1B (35-65% lost), 2B (15-35% lost), 3B (5-15% lost), 4B (< 5% lost) up to 5B which denotes the best adhesion (no detachment, no damage to scored crosshatch lines and no residue on tape upon tape removal). The term ‘zero adhesion’ denotes that it was not possible to conduct a crosshatch tape peel because the coating was detached from the substrate; hence ‘zero adhesion’ denotes worse adhesion performance than a 0B value. The crosshatch testing was conducted using 3M SCOTCH 232 Tape. Two grids / tests were run for a given formulation.

[0121] After the first crosshatch adhesion test, the copper constructions coated with the crosshatched layers underwent wet etch treatment through the following three baths based on AtotechSecuriganth^MV concentrates (a 2-(2butoxyethoxy)ethanol and ethylene glycol based sweller, a NaMnO4-based oxidizing etch and a hydroxylamine sulfate-based reducer).

[0122] Step 1 - Atotech Securiganth^MV Sweller concentrate based on 2-(2butoxyethoxy)ethanol and ethylene glycol (367.20 g), 25 wt.% sodium hydroxide (1.13g), deionized water (539.1 g) / 60^C / 10 mins.

[0123] Step 2 - Atotech Securiganth^MV P-Etch concentrate based on NaMnO4(183.6 g), 25 wt.% sodium hydroxide (162.0 g), deionized water (661.5 g) / 80^C / 20 mins

[0124] Step 3 - Atotech Securiganth^MV Reduction Conditioner concentrate based hydroxylamine sulfate (56.0 g), 50 wt.% sulphuric acid (62.78 g), deionized water (405.0 g) / H2SO4 / 50^C / 5 mins.

[0125] After completion of wet etch and drying, tape was applied to the crosshatched areas, a second tape peel was performed under the ASTM-D3359-09 conditions above, and any further damage and / or residue left on the tape was observed and recorded. Table 2 - Crosshatch tape peel results for various adhesion promoters at 2 wt.% loading before and after wet etch exposure. (* Approximate values for polydisperse materials based on repeat unit and excluding end groups.) Adhesion Amine Thiol Ether or 1st2ndCrosshatch Promoter groups groups carbonyl Crosshatch Adhesion (wt.% present Adhesion Tape Peel methylene Tape Peel (CH2) and methine (CH) Before wet After wet etch content) etch 1C None 0 0 None 0B Zero adhesion Amines 2C D230 2 0 Ether 5B 0B (47%)* 3C T403 3 0 Ether 5B 0B (47%)* 4C APTMS 1 0 None 1B Zero adhesion (23%) 5E P1075 2 0 None 5B 5B (94%) 6E P1071 2 0 None 5B 5B (94%) 7E MBCHA 2 0 None 4B 4B (85%) 8E IPDA 2 0 None 5B 3B (55%) 9E TMSODA 2 0 None 5B 4B (48%)10E TMSPDTA 3 0 None 5B 4B (37%) Thiols & Thioethers 11C PETMP 0 4 Carbonyl Zero NA (34%) adhesion 12C 70-30 PETMP- 0 2.8 Carbonyl Zero NA BTESPDS adhesion 13C 70-30 PETMP- 0 3.1 Carbonyl Zero NA MPTMS adhesion 14C Oxamide M1 0 2 Carbonyl 1B NA (27%) 15C Thioether M2 0 0 None 1B NA (60%) 16E DMPT 0 3 None 5B 5B (37%) 17E MOTMS(42%) 0 1 None 5B 5B 18E MPTMS 0 1 None 4B 4B (21%)

Claims

What is claimed is:

1. A method of wet-etching comprising: providing an article comprising: i) a conductive metallic substrate; ii) an insulating resin layer; and iii) a cured adhesive layer disposed between the conductive metallic substrate and insulating resin layer wherein the cured adhesive layer comprises the reaction product of: at least 50 wt.% of polyimide resin comprising maleimide moieties; at least 0.25 wt.% of amine and / or thiol compound(s), and optionally a free-radical initiator; contacting the article with at least one liquid, wherein the liquid comprises an organic solvent, an alkaline solution, or an acidic solution.

2. The method of claim 1 wherein the article is a component of a printed circuit board or integrated circuit comprising holes and residual insulating resin within the holes.

3. The method of claim 2 wherein the step of contacting the article with at least one liquid removes the residual insulating resin from the holes.

4. The method of claims 1-3 wherein at least one liquid comprises a permanganate compound or other oxidizing agent.

5. The method of claims 1-4 wherein the step of removing the residual insulating resin comprises contacting at least the residue with a first liquid comprising an organic solvent, a second liquid comprising an alkaline solution, and a third liquid comprising an acid.

6. The method of claims 1-5 wherein the insulating resin layer further comprises a second cured adhesive layer on the opposite planar surface as the i) a conductive metallic substrate.

7. The method of claim 6 further comprising applying a second conductive metallic layer to the second cured adhesive layer by electroless plating, electrolytic plating, or a combination thereof.

8. The method of claims 1-7 wherein the conductive metallic substrate(s) comprises copper including copper traces.

9. The method of claim 8 wherein the copper has a surface roughness (Ra) of less than 2, 1, 0.5, or 0.1 microns.

10. The method of claims 1-9 wherein the cured adhesive layer disposed on the conductive metallic substrate has a cross hatch adhesion of at least 2B, 3B, 4B, or 5B before and after contact with the at least one liquid.

11. The method of claims 1-10 wherein the polyimide has the formula:

12. The method of claim 11 wherein Q is an aromatic group including a reaction product of bisphenol-A- dianhydride; biphenyl tetracarboxylic dianhydride; and pyromellitic dianhydride.

13. The method of claim 1-12 wherein the amine and / or thiol compound(s) lack an aromatic group and comprise a C4-C60 hydrocarbon moiety.

14. The method of claim 13 wherein the hydrocarbon moiety is substituted with sulfur or NH.

15. The method of claim 13 wherein the compound does or does not comprise .

16. The method of claims 1-15 wherein the amine and / or thiol compound(s) lacks ether, carbonyl moieties, and hydroxyl moieties.

17. The method of claims 13-16 wherein the amine and / or thiol compound(s) comprise at least 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 7075, 80, 85 or 90 wt.% methylene (CH2) and / or methine (CH).

18. The method of claims 1-17 wherein the cured adhesive layer comprises at least one thiol compound.

19. The method of claims 13-18 wherein the amine and / or thiol compound(s) comprises at least one terminal alkoxy silane group and a hydrocarbon moiety with at least four carbon atoms.

20. A composition comprising: at least 50 wt.% of polyimide resin comprising maleimide moieties; and at least 0.25 wt.% of amine and / or thiol compound(s) according to claims 13-19.

21. The composition of claim 20 further characterized by claims 10-12.

22. An electronic article or component thereof comprising: at least one conductive metallic substrate or metallic layer comprising the cured composition according to claims 20-21.

23. The electronic article of claim 22 wherein the cured composition is a coating.

24. The electronic article of claim 22 wherein the cured composition is an adhesive that bonds the conductive metallic substrate or metallic layer to an insulating resin layer.

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