Laminations with polymer films and metal layers

Abstract

According to one aspect, a lamination comprises a polymer film and a first metal layer adhered to the polymer film. The polymer film contains an electrically conductive filler and has a surface resistance of no more than 1 megaohm / square. The first metal layer has a thickness of no more than 100 µm. The lamination contains less than 15 ppm of Pd. The metal layer is formed on the polymer film by direct electrochemical deposition.

Description

AREA OF REVELATION

[0001] The field of this disclosure is laminations with polymer films and metal layers. GENERAL STATE OF THE ART

[0002] Flexible copper claddings (FCCs) are required for a wide variety of applications, including consumer electronics circuits, electromagnetic shielding foil, battery current collectors, and resistance heaters for wind turbines. Typically, polyimide films, such as those used for FCCs, are metalized by lamination, by a pour-on-copper process, or by depositing a seed layer followed by electrolytic metal plating. As these applications evolve, thinner dielectrics and copper elements are required to provide either finer traces and switching areas, reduce overall device dimensions, or reduce device weight.The use of a conductive seed layer followed by electrolytic metal plating is an effective method for depositing copper thin films, as this technique allows for the deposition of copper at any desired thickness. However, depositing the seed layer can be costly or alter the electronic properties of the cladding.

[0003] Metal-clad laminates, such as copper-clad laminates, are used in electronic devices for a wide variety of electronic components intended for flexible circuits, as well as for circuit packages. Copper-clad laminates based on polyimide films are typically fabricated either by lamination, when metal thicknesses greater than 5 µm are desired, or by sputtering, when metal thicknesses less than 5 µm are desired. Electroplating (e.g., electroplating or electroless plating) is an alternative laminate fabrication method that has received some attention but is not widely used for producing laminates with a copper thickness of less than 5 µm. Furthermore, it is generally accepted that the reliability of electroplated polyimide copper laminates does not meet customer standards for electronic devices.

[0004] Metal-clad laminates produced by electroplating have traditionally exhibited poor thermal reliability compared to metal-clad laminates produced by sputtering or lamination of copper foils. The highest-reliability electroplating laminates have utilized nickel seed layers without external electroplating. Adhesion between electroplated copper and polyimide films is difficult due to the presence of volatiles in the film, the attack of the film surface by the electroplating chemicals, and the use of film materials that lack functional groups for strong chemical bonding to copper.

[0005] In addition, during operation of electronic devices, electric and magnetic fields are generated by the electronic components within the device, which can interfere with the operation of other electronic components in the same device or other nearby devices. This phenomenon is known as electromagnetic interference (EMI). Due to their high electrical conductivity, which allows them to absorb EMI waves, metals are often used for EMI shielding. The extent of shielding effectiveness is not constant for the respective shielding material but is influenced by the frequency of the incoming signal. The shielding effectiveness is determined by: a) the electrical conductivity of the shield; b) the thickness, uniformity, and smoothness of the shield; c) the physical properties of the shield; d) the frequency and impedance of the applied field; and e) the magnetic permeability of the material.Furthermore, thin shielding foils are required, which contain a thin metal layer for EMI shielding of electronic components. DETAILED DESCRIPTION

[0006] According to a first aspect, a lamination comprises a polymer film and a first metal layer adhered to the polymer film. The polymer film includes an electrically conductive filler and has a surface resistance of at most 1 megaohm / square. The first metal layer has a thickness of at most 100 µm. The lamination has less than 15 ppm of Pd. The metal layer is formed on the polymer film by electrochemically depositing the first metal layer directly onto the polymer film.

[0007] Polymer films adhered to metal layers can be used to form laminations. According to one embodiment, polymer compositions that can be suitably used for polymer films include polyimides (PI), poly(amide-imides) (PAI), poly(ester-imides), poly(amide-ester-imides), polycarbonates (PC), polyethylene naphthalates (PEN), polystyrenes (PS), poly(methyl methacrylates) (PMMA), polyethylene terephthalates (PET), polyethylene terephthalate glycols (PETG), polycyclohexylenedimethylene terephthalate glycols (PCTG), polyetherimides (PEI), polysulfones, polyethersulfones, polyarylsulfones, polyaryletherketone (PAEK) such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), and cyclic olefin copolymers. According to one embodiment, polymer compositions having an imide group are of particular use.Polymer compositions containing an imide group and aromatic monomers typically exhibit very high thermal, chemical and electrochemical stability at the low (anodic) and high (cathodic) potentials used in lithium-ion batteries.

[0008] Depending on the context, "diamine" is used herein to mean: (i) its unreacted form (i.e., a diamine monomer); (ii) its partially reacted form (i.e., a portion or portions of an oligomer or other polymer precursor derived from, or otherwise associateable with, a diamine monomer); or (iii) its fully reacted form (a portion or portions of the polymer derived from, or otherwise associateable with, a diamine monomer). The diamine may be provided with one or more functional building blocks, depending on the particular embodiment selected in the practice of the present invention.

[0009] Indeed, the term "diamine" should not be construed as limiting (or to be interpreted literally) the number of amine moieties in the diamine component. For example, paragraphs (ii) and (iii) above include polymer materials having two, one, or zero amine moieties. Alternatively, the diamine may be provided with additional functional amine moieties (in addition to the amines at the ends of the monomer that react with dianhydride to extend a polymer chain). Such additional amine moieties could be used to crosslink the polymer or to provide the polymer with further functional groups.

[0010] Similarly, the term "dianhydride," as used herein, should be understood to mean the component that reacts with (is complementary to) the diamine and, in combination, is capable of reacting to form an intermediate (which can then be cured to form a polymer). Depending on the context, "anhydride," as used herein, may refer not only to an anhydride building block per se, but also to a precursor to an anhydride building block, such as: (i) a pair of carboxylic acid groups (which can be converted to anhydride by dehydration or similar reactions), or (ii) an ester functional group of an acid halide (e.g., chloride) (or any other currently known or future developed functional group) which can be converted to an anhydride functional group).

[0011] Depending on the context, "dianhydride" may refer to: (i) the unreacted form (i.e., a dianhydride monomer, regardless of whether the anhydride functional group is in a true anhydride form or in a precursor to the anhydride form, as explained in the previous paragraph); (ii) a partially reacted form (i.e., the portion or portions of an oligomer or other partially reacted or precursor-like polymer composition obtained by reaction from, or otherwise attributable to, the dianhydride monomer); or (iii) a fully reacted form (the portion or portions of the polymer derived from, or otherwise attributable to, a dianhydride monomer).

[0012] The dianhydride may be provided with one or more functional building blocks, depending on the particular embodiment selected in the practice of the present invention. Indeed, the term "dianhydride" is not intended to be limiting (or to be interpreted literally) as to the number of anhydride building blocks in the dianhydride component. For example, (i), (ii), and (iii) (in the preceding paragraph) include organic materials that may have two, one, or zero anhydride building blocks, depending on whether the anhydride is a precursor or has already been reacted. Alternatively, the dianhydride component may be provided with additional functional anhydride-like building blocks (in addition to the anhydride building blocks that react with diamine to form a polymer).Such additional anhydride building blocks could be used to crosslink the polymer or to provide the polymer with additional functional groups.

[0013] Any of several polymer manufacturing processes may be used to produce polymer films. It would be impossible to discuss or describe all of the manufacturing processes potentially useful in practicing the present invention. It should be understood that the monomer systems of the present invention are capable of providing the advantageous properties described above in a variety of manufacturing processes. The compositions of the present invention can be prepared according to the present description, being readily prepared in any of many (perhaps innumerable) ways available to those of ordinary skill in the art using any conventional or non-conventional manufacturing technique.

[0014] While methods and materials similar or equivalent to those described herein may be used to practice or test the invention, suitable methods and materials are described herein.

[0015] When an amount, concentration, or other value or parameter is given as a range, a preferred range, or a list of maximum and minimum preferred values, this is to be construed as a specific disclosure of all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether the ranges are separately disclosed. When a range of numerical values ​​is recited herein, that range includes its endpoints and all integers and fractions within the range, unless otherwise stated. It is not intended to limit the scope of the invention to the specific values ​​recited when establishing a range.

[0016] In describing specific polymers, it should be understood that applicants sometimes refer to the polymers by the monomers used to prepare them or the amounts of monomers used to prepare them. Although such a description may not include the specific nomenclature used to describe the final polymer, or it may not include process-specific product designations, any reference to monomers and amounts should be construed to refer to the polymer produced from those monomers or amounts of monomers, and the corresponding polymers and compositions thereof.

[0017] The materials, methods, and examples in this document are for illustrative purposes only and are not to be construed as limiting unless expressly stated.

[0018] The terms "comprises," "comprising," "includes," "containing," "has," "having," or any variation thereof, are used herein to cover inclusion without exclusion. For example, a method, process, article, or device that includes a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or that are inherent in that method, process, article, or device. Furthermore, "or" refers to an inclusive or, not an exclusive or, unless expressly stated otherwise.For example, a condition A or B is satisfied by any of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0019] Furthermore, 'a' or 'an' is used to describe elements and components of the invention. This is done solely for convenience and to convey the general spirit of the invention. This description should be construed as including one or at least one of them, with the singular form also covering the plural form unless another meaning is obvious.

[0020] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, it is to be understood that these elements, components, regions, layers, and / or sections are not limited by these terms. These terms are used merely to distinguish one element, component, region, layer, and / or section from another element, component, region, layer, and / or section. Thus, a first element, component, region, layer, and / or section could also be referred to as a second element, component, region, layer, and / or section without departing from the teachings of the present invention. Similarly, the terms "upper" and "lower" apply only relative to one another.When an element, component, layer, or the like is reversed, the one that was "on the bottom" before being reversed will be "on top" after being reversed, and vice versa. When an element is described as being "on" or "disposed upon another element," this means that it is on top of or below the object portion, but does not imply that it is substantially on top of the object portion with reference to any direction of gravity; it may be directly on top of the other element or there may be intervening elements. On the other hand, when an element is described as being "directly on" or "directly upon" another element, no intervening elements are present.

[0021] Furthermore, it is understood that when an element, component, region, layer and / or section is referred to as being “between” two elements, components, regions, layers and / or sections, it may represent the only element, component, region, layer and / or section between the two elements, components, regions, layers and / or sections, or there may be one or more intervening elements, components, regions, layers and / or sections. Organic solvents

[0022] Organic solvents that can be conveniently used to synthesize polymers of the present invention are preferably capable of dissolving the polymer precursor materials. Such a solvent should also have a relatively low boiling point, such as less than 225°C, so that the polymer can be dried at moderate (i.e., convenient and more cost-effective) temperatures. A boiling point of less than 210, 205, 200, 195, 190, or 180°C is preferred.

[0023] Suitable organic solvents include: N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), methyl ethyl ketone (MEK), N,N'-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetramethylurea (TMU), glycol ethyl ether, diethylene glycol diethyl ether, 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), 1,2-bis-(2-methoxyethoxy)ethane (triglyme), gamma-butyrolactone and bis-(2-methoxyethyl) ether, tetrahydrofuran (THF), ethyl acetate, hydroxyethyl acetate, glycol monoacetate, acetone, and mixtures thereof. In one embodiment, preferred solvents include N-methylpyrrolidone (NMP) and dimethylacetamide (DMAc). Diamine

[0024] In one embodiment, an aromatic diamine may be used to form a polymer having a polyimide group. Aromatic diamines may include fluorinated aromatic diamines such as 2,2'-bis-(trifluoromethyl)benzidine (TFMB), 2,2'-bis-(4-aminophenyl)hexafluoropropane, 4,4'-diamino-2,2'-trifluoromethyldiphenyl oxide, 3,3'-diamino-5,5'-trifluoromethyldiphenyl oxide, 9,9'-bis-(4-aminophenyl)fluorene, 4,4'-trifluoromethyl-2,2'-diaminobiphenyl, 4,4'-oxy-bis-[2-trifluoromethyl)benzenamine] (1,2,4-OBABTF), 4,4'-oxy-bis-[3-trifluoromethyl)benzenamine], 4,4'-thiobis-[(2-trifluoromethyl)benzenamine], 4,4'-thiobis-[(3-trifluoromethyl)benzenamine], 4,4'-sulfoxyl-bis-[(2-trifluoromethyl)benzenamine, 4,4'-sulfoxyl-bis-[(3-trifluoromethyl)benzenamine], 4,4'-keto-bis-[(2-trifluorothyl)benzenamine], 1,1-bis-[4'-(4"-amino-2"-trifluoromethylphenoxy)phenyl]cyclopentane, 1,1-bis-[4'-(4''-amino-2''-trifluoromethylphenoxy)phenyl]cyclohexane, 2-trifluoromethyl-4,4'-diaminodiphenyl ether;1,4-(2'-Trifluormethyl-4',4''-diaminodiphenoxy)benzol, 1,4-bis-(4'-Aminophenoxy)-2-[(3',5'-Ditrifluormethyl)phenyl]benzol(6F-amin), 1,4- bis-[2'-Cyano-3'(''4-aminophenoxy)phenoxy]-2-[(3',5'-ditrifluormethyl)phenyl]benzol (6FC-Diamin), 3,5-Diamino-4-methyl-2',3',5',6'-tetrafluor-4'-trifluormethyldiphenyloxid, 2,2-bis-[4(4-Aminophenoxy)phenyl]phthalein-3',5'-bis-(trifluormethyl)anilid (6FADAP) und 3,3',5,5'-Tetrafluor-4,4'-diaminodiphenylmethan (TFDAM).;

[0025] Other suitable diamines include 4,4'-diaminobiphenyl, 4,4''-diaminoterphenyl, 4,4'-diaminobenzanilide (DABA), 4,4'-diaminophenyl benzoate, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylmethane (MDA), 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, bis-[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 4,4'-bis-(4-aminophenoxy)biphenyl (BAPB), 4,4'-diaminodiphenyl ether (ODA), 3,4'-diaminodiphenyl ether, 4,4'-isopropylidenedianiline, 2,2'-bis-(3-aminophenyl)propane, 2,2-bis-(4-aminophenyl)propane, 3,3'-Dimethyl-4,4'-diaminobiphenyl, 4-aminophenyl 3-aminobenzoate, bis-(p-beta-amino-t-butylphenyl) ether, p-bis-2-(2-methyl-4-aminopentyl)benzene. In one embodiment, the diamine is a triamine, such as N,N-bis-(4-aminophenyl)-n-butylamine, N,N-bis-(4-aminophenyl)methylamine, or N,N-bis-(4-aminophenyl)aniline.

[0026] Other suitable diamines include 1,2-bis-(4-aminophenoxy)benzene, 1,3-bis(-4-aminophenoxy)benzene (RODA), 1,2-bis-(3-aminophenoxy)benzene, 1,3-bis-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)-3-(3-aminophenoxy)benzene, 1,4-bis-(4-aminophenoxy)benzene, 1,4-bis-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)-4-(3-aminophenoxy)benzene, 2,2-bis-(4-[4-aminophenoxy]phenyl)propane (BAPP), 2,2'-bis-(4-phenoxyaniline)isopropylidene.

[0027] Other suitable diamines include p-phenylenediamine (PPD), m-phenylenediamine (MPD), 2,5-dimethyl-1,4-diaminobenzene, 2,5-dimethyl-1,4-phenylenediamine (DPX), 1,4-naphthalenediamine, 1,5-naphthalenediamine, 1,5-diaminonaphthalene, m-xylylenediamine and p-xylylenediamine.

[0028] Useful diamines having an imide group may further include an aliphatic diamine such as 1,2-diaminoethane, 1,6-diaminohexane (HMD), 1,4-diaminobutane, 1,5-diaminopentane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane (DMD), 1,11-diaminoundecane, 1,12-diaminododecane (DDD), 1,16-hexadecamethylenediamine, 1,3-bis-(3-aminopropyl)-tetramethyldisiloxane, trans-1,4-diaminocyclohexane (CHDA), isophoronediamine (IPDA), bicyclo-[2.2.2]octane-1,4-diamine and combinations thereof. Aliphatic diamines suitable for implementing the invention also include those with six to twelve carbon atoms or a combination of diamines with longer and shorter chains, as long as both the developability and flexibility of the polymer are maintained. Long-chain aliphatic diamines can increase flexibility.

[0029] The diamines suitable for forming a polymer having an imide group may further include an alicyclic diamine (which may be fully or partially saturated) such as a cyclobutanediamine (e.g., cis- and trans-1,3-diaminocyclobutane, 6-amino-3-azaspiro[3,3]heptane and 3,6-diaminospiro[3,3]heptane), bicyclo[2.2.1]heptane-1,4-diamine, isophoronediamine and bicyclo[2.2.2]octane-1,4-diamine. Alicyclic diamines may also include cis-1,4-cyclohexanediamine, trans-1,4-cyclohexanediamine, 1,4-bis-(aminomethyl)cyclohexane, 4,4'-methylene-bis-(cyclohexylamine), 4,4'-methylene-bis-(2-methylcyclohexylamine), bis-(aminomethyl)norbornane. Dianhydrides

[0030] According to one embodiment, aromatic dianhydrides can be used to form a polymer containing an imide group. The dianhydrides can be used in their tetraacid form (or as mono-, di-, tri-, or tetraesters of the tetraacid) or as their diester acid halides (chlorides). However, according to some embodiments, the dianhydride form may be preferred because it is generally more reactive than the acid or ester.

[0031] Examples of aromatic dianhydrides include 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2-(3',4'-dicarboxyphenyl)-5,6-dicarboxybenzimidazole dianhydride, 2-(3',4'-dicarboxyphenyl)-5,6-dicarboxybenzoxazole dianhydride, 2-(3',4'-dicarboxyphenyl)-5,6-dicarboxybenzothiazole dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 4,4'-thiodiphthalic anhydride, bis-(3,4-dicarboxyphenyl)sulfone dianhydride, bis-(3,4-dicarboxyphenyl) sulfoxide dianhydride (DSDA), bis-(3,4-dicarboxyphenyloxadiazole-1,3,4)-p-phenylene dianhydride, bis-(3,4-dicarboxyphenyl)-2,5-oxadiazole-1,3,4-dianhydride, bis-(3',4'-dicarboxydiphenyl ether)-2,5-oxadiazole-1,3,4-dianhydride, 4,4'-oxydiphthalic anhydride (ODPA), bis-(3,4-dicarboxyphenyl)thioether dianhydride, bisphenol A dianhydride (BPADA), bisphenol S dianhydride,bis-1,3-isobenzofurandione, 1,4-bis-(4,4'-oxyphthalic anhydride)benzene, bis-(3,4-dicarboxyphenyl)methane dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, 1,3-bis-(4,4'-oxydiphthalic anhydride)benzene, 2,2-bis-(3,4-dicarboxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 9,9-bis-(trifluoromethyl)-2,3,6,7-xanthenetetracarboxylic dianhydride.

[0032] Suitable dianhydrides also include 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, bicyclo-[2,2,2]-octene-(7)-2,3,5,6-tetracarboxylic dianhydride, cyclopentadienyltetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, pyromellitic dianhydride (PMDA), tetrahydrofurantetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, Phenanthrene-1,8,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride and thiophene-2,3,4,5-tetracarboxylic dianhydride.

[0033] According to one embodiment, the dianhydrides for forming a polymer having an imide group may include alicyclic dianhydrides such as cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride (CBDA), 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 1,2,3,4-cyclohexanetetracarboxylic acid dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride (CPDA), hexahydro-4,8-ethano-1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetrone (BODA), 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride (TCA), and meso-butane-1,2,3,4-tetracarboxylic acid dianhydride.

[0034] According to an embodiment wherein the polymer further comprises aromatic amide moieties, a suitable additional dicarbonyl chloride to form the polymer may include terephthaloyl chloride (TPCI), isophthaloyl chloride (IPCI), biphenyldicarbonyl chloride (BPCI), naphthalene dicarbonyl chloride, terphenyldicarbonyl chloride, 2-fluoroterephthaloyl chloride, and trimellitic anhydride.

[0035] According to one embodiment, poly(amide-ester-imides) can be prepared from polyols that can react with carboxylic acid or the ester acid halides to produce ester compounds.

[0036] The dihydric alcohol component can be virtually any alcoholic diol containing two esterifiable hydroxyl groups. Mixtures of suitable diols may also be included. Suitable diols for the present application include, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, etc.

[0037] The polyhydric alcohol component can be virtually any polyhydric alcohol containing at least three esterifiable hydroxyl groups to provide the above-described synthetic process advantages of the present invention. Mixtures of such polyhydric alcohols can be conveniently used. Examples of suitable polyhydric alcohols include tris-(2-hydroxyethyl)isocyanurate, glycerin, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, and mixtures thereof.

[0038] In some cases, useful diamine and dianhydride monomers contain ester groups. Examples of such monomers include diamines such as 4-aminophenyl 4-aminobenzoate and 4-amino-3-methylphenyl 4-aminobenzoate, and dianhydrides such as p-phenylene bis(trimellitate) dianhydride.

[0039] In some cases, useful diamine and dianhydride monomers contain amide groups. Examples of such monomers include diamines such as 4,4'-diaminobenzamide (DABAN) and dianhydrides such as N,N'-(2,2'bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)-bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid amide) and N,N'-(9H-fluoren-9-ylidenedi-4,1-phenylene)bis[1,3-dihydro-1,3-dioxo-5-isobenzofurancarboxylic acid amide].

[0040] Higher order copolymers containing an imide group may include any of the monomers described above. Imidization catalysts

[0041] According to one embodiment, an imidization catalyst (sometimes referred to as an "imidization accelerator") can be used as a conversion chemical, which can help lower the imidization temperature for the formation of a polymer having an imide group and shorten the imidization time. Thus, the polyamidocarboxylic acid casting solutions of the present invention comprise a polyamidocarboxylic acid solution in combination with a certain amount of conversion chemicals. Conversion chemicals that can be suitably used in the present invention include, but are not limited to, (i) one or more dehydrating agents and / or auxiliary catalysts such as aliphatic acid anhydrides (acetic anhydride, trifluoroacetic anhydride, propionic anhydride, monochloroacetic anhydride, bromoadipic anhydride, etc.)) and aromatic acid anhydrides; and (ii) one or more imidization catalysts, such as aliphatic tertiary amines (triethylamine, etc.), aromatic tertiary amines (dimethylaniline, N,N-dimethylbenzylamine, etc.), and heterocyclic tertiary amines (pyridine, alpha, beta, gamma, picoline, 3,5-lutidine, 3,4-lutidine, isoquinoline, etc.) and guanidines (e.g., tetramethylguanidine). In one embodiment, an imidization catalyst does not contain any diazole. Useful dehydrating agents may further include diacetyl oxide, butyryl oxide, benzoyl oxide, 1,3-dichlorohexylcarbodiimide, N,N-dicyclohexylcarbodiimide, benzenesulfonyl chloride, thionyl chloride, and phosphorus pentachloride. According to some embodiments, the dehydrating agent may also act as a catalyst to improve the reaction kinetics for imidization.The anhydride dehydrating material is typically used in a slight molar excess over the amount of polyamidocarboxylic acid present in the polyamidocarboxylic acid solution. In one embodiment, the amount of dehydrating agent used is typically about 2.0 to 4.0 moles per equivalent of polyamidocarboxylic acid formula unit. Generally, a comparable amount of tertiary amine catalyst is used. The ratio of these catalysts and their concentration in the polyamidocarboxylic acid solution influence the imidization kinetics and film properties. Polymer films can have imidization catalysts present in the polymer film in an amount of 1 part per billion (ppb) to 1 wt. %, from 10 ppb to 0.1 wt. %, or from 100 ppb to 0.01 wt. %. Electrically conductive fillers

[0042] According to one embodiment, the electrically conductive fillers may include metals (such as gold, silver, copper, etc.), conductive mixed metal oxides (such as cuprates, superconducting oxides, indium tin oxide, antimony tin oxide, mixed titanium / tin / zirconium oxides, etc.), organic compounds such as polyaniline, polythiophene, polypyrrole, polyphenylenevinylene, polydialkylfluorenes, carbon black, graphite, graphene, multi-walled and single-walled carbon nanotubes and other nanotube structures, and carbon nanofibers. According to one embodiment, an electrically conductive filler may be an inorganic filler, an organic filler, or a mixture thereof.

[0043] According to one embodiment, an electrically conductive filler is carbon black. According to one embodiment, the electrically conductive filler is selected from the group consisting of acetylene black, highly abrasion-resistant furnace black, conductive furnace black, conductive channel-type carbon black, carbon nanotubes, carbon fibers, fine gap black, and mixtures thereof. In carbon black, oxygen complexes located on the surface of the carbon particles act as an electrically insulating layer. Thus, a low volatile content is generally desirable to achieve high conductivity. However, the difficulty of dispersing the carbon black must also be considered. Surface oxidation promotes the breakup of aggregates and the dispersion of carbon black.According to some embodiments, if the electrically conductive filler is carbon black, the carbon black has a volatile content of no more than 1%. Other fillers.

[0044] According to one embodiment, other fillers for a polymer film may include other inorganic and organic fillers not described above with respect to the electrically conductive fillers. The inorganic fillers may include thermally conductive fillers, such as metal oxides, inorganic nitrides, and metal carbides. According to one embodiment, the inorganic fillers may include diamond, clay, sepiolite, mica, dicalcium phosphate, metal oxides, including magnetic metal oxides, transparent conductive oxides, and fumed metal oxides.According to one embodiment, the inorganic fillers may include inorganic oxides such as oxides of silicon, aluminum, zinc, and titanium, hollow (porous) silicon oxide, antimony oxide, zirconium oxide, indium-tin oxide, antimony-tin oxide, mixed titanium / tin / zirconium oxides, and binary, ternary, quaternary, and higher valency oxides of one or more cations selected from silicon, titanium, aluminum, antimony, zirconium, indium, tin, zinc, niobium, and tantalum. According to one embodiment, particle composites (e.g., single or multiple core / shell structures) may be used in which one oxide encapsulates another oxide within a particle.

[0045] According to one embodiment, the inorganic fillers may include other ceramic compounds, such as boron nitride, aluminum nitride, ternary or higher valent compounds containing boron, aluminum and nitrogen, gallium nitride, silicon nitride, aluminum nitride, zinc selenide, zinc sulfide, zinc telluride, silicon carbide and combinations thereof, or higher valent compounds containing multiple cations and multiple anions, which may include oxycarbides and oxynitrides.

[0046] According to one embodiment, fillers for a polymer film may have an average particle size d 50in the range of 0.1 to 10 µm, 0.1 to 5 µm, 0.2 to 5 µm, or 0.2 to 3 µm. The filler size can be determined using a laser particle size analyzer, wherein the filler is dispersed in an organic solvent (possibly with the aid of a dispersant, adhesion promoter, and / or coupling agent). The median particle size d 50corresponds to the spherical diameter, which is based on the median value of the volume distribution of the particles. If the median value of the particle size is less than 0.1 µm, the filler particles may tend to aggregate or become unstable in the organic solvents used in polymer production. If the median value of the aggregated particles exceeds 10 µm, the dispersion of the filler component in the polymer film may be inhomogeneous (or have an unsuitable size for the thickness of the film). A relatively heterogeneous dispersion of the filler component in the film may lead to insufficient mechanical elongation of the film, insufficient flexural strength of the film, and / or low dielectric strength.According to one embodiment, fillers may require extensive milling and filtration to break up unwanted particle aggregates, such as those typically encountered when attempting to disperse certain fillers in a polymer matrix. Such milling and filtration can be costly and sometimes fails to remove all unwanted aggregates. According to one embodiment, the average aspect ratio of the filler may be at least 1. According to some embodiments, the filler is selected from the group consisting of acicular fillers, fibrous fillers, platelet fillers, polymer fibers, and mixtures thereof.According to one embodiment, the fillers may have an aspect ratio of at least 1, at least 2, at least 4, at least 6, at least 8, at least 10, at least 12, at least 15, at least 25, at least 50, at least 100, at least 200 or at least 300 to 1.

[0047] According to one embodiment, the filler comprises a mixture or a uniform mixture of fillers having any number of particle types, particle sizes and particle shapes, wherein a mixture or a uniform mixture may consist of the same type of filler or a different type of filler.

[0048] According to one embodiment, fillers can be coated with a coupling agent. For example, a filler particle can be coated with an aminosilane, phenylsilane, acrylic, or methacrylic coupling agent derived from the corresponding alkoxysilanes. By reacting the fillers with hexamethyldisilazane, the particle surface can be provided with trimethylsilyl surface capping agents. According to one embodiment, the fillers can be coated with a dispersant. According to one embodiment, the fillers can be coated with a combination of a coupling agent and a dispersant. Alternatively, the coupling agent, the dispersant, or a combination thereof can be added directly to the polymer film and need not necessarily be applied to the fillers. Polymer films

[0049] According to one embodiment, a polymer film, which is a polyimide film, can be prepared by combining a diamine and a dianhydride (monomer or other polyimide precursor form) with a solvent to form a solution of polyamidocarboxylic acid (also called polyamic acid). The dianhydride and diamine can be combined in a molar ratio of approximately 0.90 to 1.10. The molecular weight of the resulting polyamidocarboxylic acid can be adjusted by adjusting the molar ratio of dianhydride to diamine.

[0050] According to one embodiment, the polyamidocarboxylic acid casting solution originates from the polyamidocarboxylic acid solution. The polyamidocarboxylic acid casting solution and / or the polyamidocarboxylic acid solution are contacted with conversion chemicals such as: (i) one or more dehydrating agents, such as aliphatic acid anhydrides (acetic anhydride, etc.) and / or aromatic acid anhydrides; and (ii) one or more catalysts, such as aliphatic tertiary amines (triethylamine, etc.), aromatic tertiary amines (dimethylaniline, etc.), and heterocyclic tertiary amines (pyridine, picoline, isoquinoline, etc.). The anhydride dehydrating material is often used in a slight molar excess over the amount of polyamidocarboxylic acid present in the polyamidocarboxylic acid solution.The amount of acetic anhydride used is typically approximately 2.0 to 4.0 moles per equivalent (repeating unit) of polyamidocarboxylic acid. Generally, a comparable amount of tertiary amine catalyst is used. Fillers dispersed or suspended in solvent as described above are then added to the polyamidocarboxylic acid solution.

[0051] According to one embodiment, the polyamidocarboxylic acid solution is dissolved in an organic solvent at a concentration of approximately 5.0 or 10 percent to 15, 20, 25, 30, 35, or 40 percent by weight. According to one embodiment, a slurry comprising an electrically conductive filler is prepared, wherein the slurry has an electrically conductive filler content in the range of 0.1 to 70, 0.5 to 60, 1 to 55, 2 to 50, or 5 to 45 weight percent. The slurries may, but are not required to, be ground to the desired particle size using a ball mill. The slurries may, but are not required to, be filtered to remove remaining large particles. A polyamidocarboxylic acid solution may be prepared by methods well known in the art. The polyamidocarboxylic acid solution can be filtered, but this does not have to be done.According to some embodiments, the solution is mixed with the filler in a high-shear mixer. If a polyamidocarboxylic acid solution is prepared with a slight excess of diamine, additional dianhydride solution may be added to increase the viscosity of the mixture to the desired level for film casting. The amount of polyamidocarboxylic acid solution and filler slurry may be adjusted to achieve the desired levels in the cured film. According to some embodiments, the mixture is cooled to below 10°C and mixed with conversion chemicals prior to casting.

[0052] The solubilized mixture (the polyamidocarboxylic acid solution) can then be cast or applied onto a support, such as a continuous belt and a rotating drum, to obtain a partially imidized gel film. Alternatively, it can be cast onto a polymeric support such as PET, other forms of Kapton® polyimide film (e.g., Kapton® HN or Kapton® E films), or other polymeric supports. The gel film can be peeled from the drum or belt, placed on a stretching frame, and cured in an oven using convection and radiant heat to remove the solvent and complete the imidization to a solids content above 98%. The film can then be separated from the support and oriented, such as by stretching, and further heated (dried and cured) to obtain a polyimide film.

[0053] Convenient processes for producing polyimide films can be found in U.S. Patent Nos. 5,166,308 and 5,298,331, the entire teachings of which are incorporated herein by reference. Numerous modifications are possible, such as (a) A process in which the diamine components and dianhydride components are mixed together beforehand and the mixture is then added portionwise to a solvent with stirring. (b) A process in which a solvent is added to a stirred mixture of diamine and dianhydride components. (As opposed to (a) above) (c) A process in which only diamines are dissolved in a solvent and then dianhydrides are added in such a ratio that the reaction rate can be controlled. (d) A process in which only the dianhydride components are dissolved in a solvent and then the amine components are added in such a ratio that the reaction rate can be controlled. (e) A process in which the diamine components and the dianhydride components are dissolved separately in solvents and these solutions are then mixed in a reactor. (f) A process in which the polyamidocarboxylic acid with excess amine component and another polyamidocarboxylic acid with excess dianhydride component are formed in advance and then reacted with each other in a reactor, in particular in such a way that a non-random copolymer or a block copolymer is formed. (g) A process in which a certain portion of the amine components and the dianhydride components are first reacted and then the remaining diamine components are reacted, or vice versa. (h) A process in which the conversion chemicals (catalysts) are mixed with the polyamidocarboxylic acid to form a polyamidocarboxylic acid casting solution and then cast to form a gel film. (i) A process in which all or part of the components are added in any order to either a portion or all of the solvent, it being possible for a portion or all of the component to be added as a solution to a portion or all of the solvent. (j) A process in which one of the dianhydride components is first reacted with one of the diamine components to thereby obtain a first polyamidocarboxylic acid. Subsequently, the other dianhydride component is reacted with another amine component to obtain a second polyamidocarboxylic acid. The amidocarboxylic acids are then combined in any of a number of ways prior to the formation of the thin film.

[0054] According to one embodiment, the solubilized mixture (the polyamidocarboxylic acid casting solution) can be mixed with a crosslinking precursor, after which it is cast to form a polymer film. According to one embodiment, a polymer film contains a crosslinked polymer in a range of 80 to 99 wt. %. According to some embodiments, the polymer film contains between any two of the following values, including the following: 80, 85, 90, 95, and 99 wt. % of crosslinked polymer. According to yet another embodiment, the polymer film contains 91 to 98 wt. % of crosslinked polymer.

[0055] According to one embodiment, the crosslinking reaction involves chemical compounds, such as reactive amines, that can participate in a chemical reaction that crosslinks the polymer chains in the film. According to one embodiment, heat can be used to crosslink the polymer. According to one embodiment, irradiation with a light source can be used to crosslink the polymer via a photoinitiated process. According to one embodiment, an additional reactive chemical species can be used to crosslink the polymer. According to one embodiment, any combination of these approaches can be used to crosslink the polymer.

[0056] The crosslinking of the polymer can be determined using various methods. According to one embodiment, the gel fraction of the polymer can be determined using an equilibrium swelling method, wherein the weight of a dried thin film is determined before and after crosslinking. According to one embodiment, a crosslinked polymer can have a gel fraction in the range of 20 to 100%, 40 to 100%, 50 to 100%, 70 to 100%, or 85 to 100%. According to one embodiment, the crosslinked structure can be identified using rheological methods. An oscillatory time-course measurement at specific load, frequency, and temperature can be used to confirm the formation of a crosslinked structure. Initially, the loss modulus value (G") is higher than the storage modulus value (G'), indicating that the polymer solution behaves like a viscous liquid.Over time, the formation of a cross-linked polymer structure is illustrated by the crossing of the G' and G'' curves. This crossing, which corresponds to the so-called "gel point," occurs at the point at which the elastic component predominates over the viscous component.

[0057] According to one embodiment, electrically conductive filler is first dispersed in a solvent to form a slurry. The slurry is then dispersed in the polyamidocarboxylic acid solution. According to one embodiment, the concentration of electrically conductive filler to the polyimide (in the final film product) is in the range of 5 to 65 wt. %, 5 to 50 wt. %, 10 to 40 wt. %, or 15 to 35 wt. %, based on the total weight of the polymer film. According to one embodiment, the concentration of electrically conductive filler to the polyimide (in the final film product) is at least 5, at least 10, at least 15, at least 20, or at least 25 wt. %, based on the total weight of the polymer film.The composition of the cured film can be calculated from the composition of the ingredients in the mixtures, excluding the DMAc solvent (which is removed during curing) and taking into account the dehydration during the conversion of polyamidocarboxylic acid to polyimide. When using electrically conductive fillers, the conductivity of the polyimide film increases with increasing filler concentration. According to one embodiment, an electrically conductive polymer film can have a surface resistivity of 1 megohm / square or less, 0.5 megohm / square or less, 0.1 megohm / square or less, or 50,000 ohms / square or less. Those skilled in the art will understand that, in addition to the amounts added, the properties of electrically conductive fillers, such as particle size, morphology, aspect ratio, surface oxidation, etc., also play a role., influence the surface resistance of the polymer film in which they are contained.

[0058] According to one embodiment, the filler slurry is uniformly mixed with a polyamidocarboxylic acid solution to form the filled polyamidocarboxylic acid casting solution using a high-shear mixing process. According to this embodiment, if the filler is present at more than 65 weight percent in the final film product, the film may be too brittle and may not be sufficiently flexible to form an unsupported, mechanically robust, flexible sheet. Furthermore, if the filler is present at less than 5 weight percent, the resulting films may not be sufficiently conductive.

[0059] According to one embodiment, the casting solution may further contain a number of additives, such as processing aids (e.g. oligomers), antioxidants, light stabilizers, flame retardant additives, antistatic agents, heat stabilizers, UV absorbers or various reinforcing agents.

[0060] According to one embodiment, a coextrusion process can be used to form a multilayer polymer film with two or more layers, for example, a three-layer polymer film with an inner core layer between two outer layers. In this process, for a three-layer polyimide film, a finished polyamidocarboxylic acid solution is filtered and pumped to a slot die, where the stream is split to form the first outer layer and the second outer layer of a three-layer coextruded film. According to some embodiments, a second polymer stream is filtered and then pumped into a die to form the middle polymer core layer of a three-layer coextruded film. The flow rates of the solutions can be adjusted to achieve the desired layer thickness.According to one embodiment, the polymer composition and filler content of the first and second outer layers are the same, while according to another embodiment, the polymer composition and / or filler content of the first and second outer layers are different. According to some embodiments, the polymer composition and filler content of the core layer may be the same or different from those of one or both outer layers.

[0061] According to one embodiment, the multilayer film is produced by simultaneously extruding the first outer layer, the core layer, and the second outer layer. According to some embodiments, the layers are extruded through an extrusion die with one or more cavities. According to another embodiment, the multilayer film is produced using a single-cavity die. When a single-cavity die is used, the laminar flow of the material streams should have a sufficiently high viscosity to prevent mixing of the streams and ensure uniform stratification. According to some embodiments, the multilayer film is produced by casting from the slot die onto a moving stainless steel belt.According to one embodiment, for a polymer containing an imide group, the tape is then passed through a convection oven to evaporate the solvent and partially imidize the polymer, forming a "green" film. The green film can be peeled off the cast tape and wound onto a coil. The green film can then be passed through a stretching oven to obtain a fully cured polymer film. According to some embodiments, shrinkage during stretching can be minimized by holding the film at the edges (namely, using clamps or pins).

[0062] According to one embodiment, the outer layers of the present invention may also be applied to the core layer during an intermediate manufacturing stage of polymer films, such as gel films or green films.

[0063] In the formation of an imide-containing polymer, the term "gel film" refers to a polyamidocarboxylic acid film loaded with volatiles, primarily solvents, such that the polyamidocarboxylic acid transforms into a gel-like, swollen or rubbery state and can be formed in a chemical conversion process. The volatile content is typically in the range of 70 to 90% by weight, and the polymer content is typically in the range of 10 to 30% by weight of the gel film. The final film becomes self-supporting in the gel film state. It can be peeled off from the support onto which it was cast and heated to a final curing temperature. The gel film generally has an amidocarboxylic acid to imide ratio ranging from 10:90 to 50:50, with a most common ratio being 30:70.

[0064] The gel thin-film structure can be manufactured using the process described in U.S. Patent No. 3,410,826. This patent describes the addition of a chemical conversion agent and a catalyst, such as a lower fatty acid anhydride and a tertiary amine, to the polyamidocarboxylic acid solution at low temperatures. The polyamidocarboxylic acid solution is then cast in a thin film onto a casting drum. After casting, the thin film is gently heated, for example, to 100°C, to activate the conversion agent and catalyst and convert the cast thin film into a polyamidocarboxylic acid / polyimide gel thin film.

[0065] Another type of polymer thin film is a "green thin film," such as a polyimide thin film consisting partly of polyamidocarboxylic acid and partly of polyimide, and can be formed in a thermal conversion process. Green thin films generally contain 50 to 75% by weight of polymer and 25 to 50% by weight of solvent. In general, such a film should be strong enough to be essentially self-supporting. Green thin films can be prepared by casting the polyamidocarboxylic acid solution as a thin film onto a suitable support, such as a casting drum or casting belt, and removing the solvent by gentle heating up to 150°C. A small proportion of amidocarboxylic acid units in the polymer, e.g., up to 25%, may be converted to imide units.

[0066] The polymer films of the present invention can be applied in any number of ways. These methods include using a slot die, dip coating, or roll coating of a film followed by sizing with a doctor blade, doctor rolls, nip rolls, or an air jet. The coating can also be applied by brushing or spraying. The use of such techniques makes it possible to produce both single- and double-coated laminates. In producing double-coated structures, the coatings can be applied to both sides of a polymer either simultaneously or sequentially, prior to the polymer curing and drying step.

[0067] The thickness of the polymer film can be adjusted depending on the intended use of the film or the final application specifications. According to one embodiment, the polymer film has a total thickness in a range of 1 to 300 µm, 2 to 200 µm, 5 to 150 µm, 10 to 100 µm, or 20 to 80 µm.

[0068] According to one embodiment for a two- or three-layer polymer film, the core layer has a thickness in a range of 0.75 to 225 µm, 1.5 to 150 µm, 3.75 to 112.5 µm, or 7.5 to 75 µm, and the outer layer(s) each have a thickness in a range of 0.25 to 75 µm, 0.5 to 50 µm, 1.25 to 37.5 µm, or 2.5 to 25 µm. According to one embodiment, in a three-layer film, the thicknesses of the outer layers can be the same or different. Laminations

[0069] According to one embodiment, a lamination may comprise a polymer film and a metal layer adhered to the polymer film. According to one embodiment, a lamination may comprise a polymer film with metal layers adhered to both sides of the polymer film.

[0070] Laminations can be formed as single-sided or double-sided laminates using a number of known methods. In one embodiment, a metal electroplating process can be used to form a laminate, such as a polyimide film. In one embodiment, a polyimide film comprises a thermoplastic polyimide layer. A metal layer can be formed on the thermoplastic polyimide layer of the polyimide film by electroplating a metal layer. In one embodiment, a metal layer can be formed. In one embodiment, a metal layer can be 100 µm or less, 50 µm or less, 25 µm or less, 10 µm or less, 5 µm or less, 3 µm or less, or 1 µm or less thick. By using an electroplating process to form metal layers on polymer films, smoother interfaces can be formed.In the conventional lamination of metal foils to polymer films, the surface roughness of the films is important to ensure good adhesion to the polymer film, although roughnesses greater than the thickness of a thin metal layer may also be required.

[0071] According to one embodiment, a polymer film can be bonded to a first metal layer in an electroplating process to form a one-sided lamination. According to one embodiment, the surface of the polymer film to be electroplated can be plasma-treated before the metal layer is formed. Thus, once formed, the lamination comprises the polymer film and a thin conductive layer. According to one embodiment for a multilayer polymer film, the use of a thermoplastic polymer layer as an outer layer for bonding to the metal layer makes it possible to achieve strong adhesion between the polymer film and the metal layer, despite the smooth nature of the interface between the layers and without the use of additional primer or adhesive layers in between.

[0072] According to one embodiment, a polymer film can be bonded to a first metal layer by directly electrochemically depositing a metal layer onto a polymer film (direct metallization). The term "direct electrochemical deposition of a metal layer" or "direct electroplating" onto a polymer film means that an electrolytic coating process is used to form and build up a metal layer on a polymer film without first applying an electroless electroplating process, a physical vapor deposition process, or a chemical vapor deposition process to form a first metal layer on the polymer film. By eliminating such a seed layer from the process flow, direct metallization is faster and more cost-effective than conventional methods for producing copper cladding.According to one embodiment, the cladding is essentially free of Pd. "Essentially free of Pd" should be understood to mean that no significant amount of Pd is detectable in the cladding when analyzed by inductively coupled plasma mass spectrometry (ICP-MS) as described below. Essentially free of Pd means that less than 15 ppm, less than 10 ppm, or less than 5 ppm of Pd is detectable. In some cases, traces of Pd can be detected in the digested cladding using ICP-MS, even though no Pd catalyst was used in the metallization process. However, in the case of a Pd-catalyzed process, Pd values ​​above 5 ppm, 10 ppm, or 15 ppm can also be detected. For example, a process using a Pd catalyst could use 200 ppm of Pd metal, and concentrations of approximately 20 ppm can be detected in the cladding using ICP-MS.

[0073] According to one embodiment, a polymer film can be bonded to the first and second metal layers to form a double-sided lamination. One or both of the metal layers can be formed using an electroplating process. According to one embodiment, the surfaces of the polymer film to be electroplated can be plasma-treated prior to formation of the metal layers. According to one embodiment, the thicknesses of the first and second metal layers can each be 100 µm or less, 50 µm or less, 25 µm or less, 10 µm or less, 5 µm or less, 3 µm or less, or 1 µm or less. According to one embodiment, the thicknesses of the metal layers can be the same or different.According to one embodiment, a double-sided lamination may comprise a thin metal layer on one side and a metal foil on the other side, wherein the thin metal layer is formed using an electroplating process and the metal foil is subsequently laminated to the lamination on a side opposite the thin metal layer. According to one embodiment, a metal foil may have a thickness in a range of 5 to 200 µm, 5 to 100 µm, 10 to 75 µm, or 10 to 50 µm. According to one embodiment for a multilayer polymer film, the use of a thermoplastic polymer layer as an outer layer for bonding to the metal layer(s) makes it possible to achieve strong adhesion between the polymer film and the metal layer(s), despite the smooth nature of the interface between the layers and without the use of additional primer or adhesive layers in between. Applications

[0074] According to one embodiment, the laminations of the present invention are useful for die-pad bonding of flexible printed circuit boards or semiconductor devices or packaging materials for CSP (Chip Scale Package), Chip-on-Flex (COF), COL (Chip-on-Lead), LOC (Lead-on-Chip), Multi-Chip Modules (“MCM”), Ball Grid Arrays (“BGA” or Micro-Ball Grid Array) and / or Tape-Automated Bonding (“TAB”).

[0075] According to another embodiment, the laminations of the present invention can be used for wafer-level integrated circuit packages, wherein a composite material is fabricated using a polymer film according to the present invention sandwiched between a conductive layer (typically a metal) with a thickness of less than 100 µm and a wafer comprising a plurality of integrated circuit chips. According to one embodiment (for wafer-level integrated circuit packages), the conductive via is connected to the chips via a conductive via, such as a wire bond, a conductive metal, a solder pad, or the like.

[0076] According to another embodiment, the laminations of the present invention are used as a material for fabricating a planar transformer component. Such planar transformer components are commonly used in power supply devices.

[0077] According to another embodiment, the laminations of the present invention are used as a material for fabricating high-density integrated circuits (HDICs) that have ultrafine features such as very narrow pitches and very fine lines and pitches, which support good signal integrity during high-speed, high-frequency signal transmissions. Such circuits are used for the fabrication of display modules, touch-sensor surfaces, sensors, and camera modules in mobile electronic devices.

[0078] According to one embodiment, a shielding film that provides EMI shielding for electronic devices and components such as flexible circuit boards, antennas, and chip-on-flex devices comprises a lamination. To provide EMI shielding, the shielding film contains a uniform metal layer that is highly conductive, adheres tightly to the base material, and maintains high electrical conductivity over time.

[0079] According to another embodiment, the laminations of the present invention can be used with thick metal foils to form resistance heaters, as described in U.S. Patent Application No. 2011 / 0229680 A1. Such heaters are typically used in automotive and aerospace applications.

[0080] According to one embodiment, laminations comprising a polymer film and first and second metal layers adhered to the polymer film can be used as current collectors in electrochemical devices such as lithium-ion batteries, capacitors, supercapacitors, fuel cells, and redox flow batteries. Any electrochemical device in which the conductivity of a current collector can be useful to close an electrical circuit and power an external device could benefit from the use of current collectors comprising a polymer film and metal layers adhered to the polymer film. For example, a lithium-ion cell comprises a positive electrode (cathode), a negative electrode (anode), and a separator, at least one, preferably all, of which are in ionically conductive contact with an electrolyte solvent.

[0081] The advantageous properties of the present invention can be determined from the following examples, which illustrate but do not limit the invention. All parts and percentages are by weight unless otherwise stated. EXAMPLESTest methodsParticle size

[0082] The particle size of the filler particles in the slurries was measured by laser diffraction using a particle size analyzer (Mastersizer 3000, Malvern Instruments, Inc., Westborough, MA, USA). DMAc was used as the carrier fluid. Surface resistance

[0083] According to ASTM D257, a Loresta AX MCP-T370 instrument with a PSP linear 4-point probe (Mitsubiushi Chemical Analytech Co., LTD, Kanagawa, Japan) was used to measure surface resistivity at 15 locations evenly distributed across an approximately 12 x 12 inch piece of polymer film. The 15 readings were averaged to determine the surface resistivity of the film. Surface resistivity can be measured on both sides of the polymer film containing electrically conductive fillers. Detection of metals

[0084] Approximately 300 mg of the lamination was digested with aqua regia in closed microwave digestion vessels at 900 W for 15 minutes. The internal temperatures of the vessels reached ~250°C. After digestion, the samples were cooled to room temperature and checked for complete dissolution of the solids. The samples were then placed on a hot plate to expel the aqua regia. After reaching dryness, each sample was reconstituted in a 2% (v / v) HNO3 solution. The diluted samples were analyzed in triplicate for 105-Pd using He and H2 collision cell gas on an inductively coupled plasma mass spectrometer (7700 ICP-MS 6, Agilent Technologies, Santa Clara, CA, USA). Slurry of carbon black

[0085] For some embodiments, a carbon black slurry was prepared to provide an electrically conductive filler, consisting of 9.5 wt.% carbon black powder (Conductex® 7055U, Aditya Birla Group, Marietta, GA, USA), 17.25 wt.% polyamidocarboxylic acid (13.06 wt.% PMDA / ODA and 4.19 wt.% PMDA / BPDA / ODA / PPD), and 73.25 wt.% DMAc. To complete the uniform dispersion of the particles in the slurry, high-shear milling and mixing were used. The median particle size d 50 (corresponding to the sphere diameter based on a median value of the volume distribution of the particles) of the filler particles was less than 1 µm. Multilayer polymer film

[0086] Polyamidocarboxylic acid solutions for the core and outer layers were prepared separately by a chemical reaction between the corresponding molar equivalents of the monomers in the solvent dimethylacetamide (DMAc). Typically, the diamine dissolved in DMAc was stirred under a nitrogen atmosphere, and the dianhydride was added as a solid over a period of several minutes. Stirring was continued to achieve the highest possible viscosity of the polyamidocarboxylic acid. The carbon black slurry (in an appropriate amount to achieve the desired surface resistance) was added to the polyamidocarboxylic acid solutions and mixed using a high-shear mixer. The viscosity was adjusted by controlling the amount of dianhydride in the polyamidocarboxylic acid solution. Examples 1 to 3

[0087] For Examples 1 to 3 (E1 to E3), a two-layer polyimide film with an electrically conductive layer on one side and a dielectric insulator on the other side (DuPont™ Kapton® 200RS100, available from DuPont de Nemours, Inc., Wilmington, DE, USA) was used as the multilayer polymer film. Both layers contained a polyimide obtained from a molar ratio of dianhydride to diamine of approximately 1:1, where the dianhydride was PMDA and the diamine was ODA. For these films, the surface resistance was measured at the surface provided with the electrically conductive layer. Example 4

[0088] For Example 4 (E4), the polymer composition of the core layer contained a polyimide obtained from a dianhydride to diamine molar ratio of approximately 1:1. The dianhydride composition contained the monomers BPDA / PMDA in a molar ratio of 88:12, and the diamine composition contained the monomers PPD / ODA in a molar ratio of 95:5. The thermoplastic outer layers further contained a polyimide obtained from an approximately 1:1 molar ratio of dianhydride to diamine. The dianhydride composition contained the monomers PMDA and ODPA in a molar ratio of 20:80, and the diamine composition consisted of 100 mol% RODA monomer.

[0089] The multilayer films were cast by coextrusion. Three separate streams of polyamidocarboxylic acid polymers were simultaneously extruded through a multi-extrusion die onto a heated, moving belt to form a coextruded three-layer polyimide film. The flow rates of the polyamidocarboxylic acid solutions were adjusted to produce a three-layer film in which the core layer was approximately 38 µm thick and the thermoplastic outer layers were each approximately 6 µm thick. The film of E4 contained enough carbon black slurry to provide a surface resistivity of approximately 100 Ω / square.

[0090] The extruded multilayer film was dried at an oven temperature ranging from approximately 95 to approximately 150 °C. The self-supporting film was peeled from the tape and heated with radiant heaters in a stretching oven to a temperature of approximately 110 to approximately 805 °C (radiant heater surface temperature) to completely dry and imidize the polymers.

[0091] Films E1 to E4 were metallized with copper to form a metal layer on a polymer film. Prior to metallization, film samples were heated to approximately 5 mm 2 or 25 in 2cut to size and clamped in a stainless steel frame. All foil surfaces were cleaned using a two-step plasma treatment process. Cleaning was performed under a 300 mTorr plasma exposure with an N2 / CF4 / O2 mixture for 5 minutes in the first step, followed by a 30-second exposure to O2 plasma in the second step. After plasma treatment, the foils were immersed in 1M sodium hydroxide solution at 45°C for 90 seconds with gentle stirring and then rinsed with running tap water for 2 minutes. Finally, the foils were electrolytically coated in a plating cell as described below.

[0092] Electroplating was performed using a DuPont MICROFILL™ EVF-II process. The copper plating baths were prepared by combining 200 g / L of copper in the form of copper sulfate pentahydrate, 100 g / L of sulfuric acid, 50 ppm of chloride ion, 1.25 mL / L of MICROFILL™ EVF-II XB, 33 mL / L of MICROFILL™ EVF-II XL, and 10 mL / L of MICROFILL™ EVF-II XC. The foils were electroplated in a 5.5-L or 1.5-L plating cell with a stirring air flow set at 2 L / min and a temperature controlled by a heated water bath at 24 °C (75 °F). The films were mounted between two 5 x 7 inch or 2 x 6 inch stainless steel frames with a 4.5 x 5.5 inch or 1.5 x 3.25 inch window and treated as follows: 1. The foils were electroplated in an acidic bright copper bath to a target thickness of 1 µm at a current density corresponding to the data in Table 1 for 10 minutes and 24 seconds. 2. After electrolytic copper plating, the foils were rinsed with deionized water for 120 seconds, removed from the frame, immersed in ANTITARNISH™ 7130 (DuPont) for 15 seconds, rinsed with deionized water for 30 seconds, and air dried. Comparison example 1

[0093] For Comparative Example 1 (CE1), the polymer composition contained the same polyimide as described for E4. The film was cleaned using the two-step plasma process described above, followed by a basic rinse after plasma exposure.

[0094] After plasma treatment, the CE1 foil was subjected to electroless plating prior to electroplating by successively processing the foil with a CIRCUPOSIT™ 6500 electroless copper plating process without an edge cleaning step and treating it as follows: 1. The film was immersed in CIRCUPOSIT™ 6520A Pre-Dip (DuPont de Nemours, Inc., Wilmington, DE, USA) at pH 2 for 30 seconds at room temperature with gentle stirring. 2. The film was then immersed in CIRCUPOSIT™ 6530 catalyst (DuPont) with a Pd 2+ -ion ​​concentration of 200 ppm. 3. The film was then rinsed under running tap water for 60 seconds. 4. The film was then immersed in a CIRCUPOSIT™ 6540 reducing solution (DuPont) at 32°C for 60 seconds with gentle stirring. 5. The film was then rinsed under running tap water for 60 seconds. 6. The foil was then immersed in an electroless copper plating bath of type CIRCUPOSIT™ 6550 (DuPont) for 2.5 minutes at approximately 34°C. 7. The film was then rinsed under running tap water for 60 seconds.

[0095] After electroless plating, the CE1 foil was dried and stored in a desiccator before being used for electroplating.

[0096] The electroless plating process forms a copper layer of approximately 80 to 120 nm on the polyimide film. The electroless plating process is followed by a plating process, which was carried out by subjecting the film to a stepwise treatment using the MICROFILL™ EVF-II process described above. Before being placed in the MICROFILL™ EVF-II bath, the film underwent a preparatory cleaning process, which proceeded as follows: 1. The film was pretreated with RONACLEAN™ LP-200 cleaner (DuPont) at 40°C for 120 seconds. 2. The film was then rinsed with deionized (DI) water for 120 seconds. 3. The foil was then treated in 40 g / L of sulfuric acid for 30 seconds before being transferred to the electroplating bath. Table 1 Example Polyimide outer layer Polyimide core layer Current density (ASD) Surface resistance and (Ω / sq) Coverage Pd content (ppm) E1 PMDA / ODA PMDA / ODA 0,54 96 complete 0,1 E2 PMDA / ODA PMDA / ODA 1,08 96 edge 0,0 E3 PMDA / ODA PMDA / ODA 0,27 96 complete 0,0 E4 PMDA / ODA PMDA / ODPA / / RODA 0,54 97 complete 0,0 CE1 PMDA / ODA PMDA / ODPA / / RODA 0,54 97 complete 11,7

[0097] Table 1 summarizes the film properties. The coverage by the metal layer is classified as "full" (complete coverage of the polymer film by the metal layer), "edge" (some coverage of the polymer film from the edges of the film toward the center, but with the polymer exposed in the center of the film), or "none" (essentially no metal covering the polymer film). E1 to E4 demonstrate that a direct electrolytic coating process, in which a metal layer is directly electrochemically deposited onto a polymer film, can be used to form a lamination with excellent coverage of the metal layer on the polymer film without the need for an initial electroless step using a seed layer. By adjusting the deposition parameters, such as the current density, complete coverage can be achieved. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 5,166,308

[0053] US 5,298,331

[0053] US 3,410,826

[0064] US 2011 / 0229680 A1

[0079]

Claims

[1] A lamination comprising a polymer film and a first metal layer adhered to the polymer film, wherein: the polymer film comprises an electrically conductive filler and has a surface resistance of not more than 1 megaohm / square; the first metal layer has a thickness of no more than 100 µm; the lamination contains less than 15 ppm of Pd; and the metal layer on the polymer film is formed by the first metal layer being deposited directly electrochemically on the polymer film. [2] The lamination of claim 1, wherein the polymer film comprises a polymer comprising an imide group. [3] The lamination of claim 1, wherein the polymer film comprises a multilayer film comprising: a first outer layer comprising a first polymer; a second outer layer comprising a second polymer; and a core layer comprising a third polymer, wherein the core layer is located between the first and second outer layers and the electrically conductive filler is present in one or more of the layers. [4] A lamination according to claim 3, wherein one or more of the first, second and third polymers comprise a polymer comprising an imide group. [5] Lamination according to claim 1, wherein the electrically conductive filler is present in the polymer film at a concentration in the range of 5 to 65 percent by weight, based on the total weight of the polymer film. [6] An electronic device comprising the lamination of claim 1. [7] An energy storage device comprising the lamination of claim 1, wherein the energy storage device is selected from the group consisting of lithium-ion batteries, capacitors, supercapacitors, fuel cells, and redox flow batteries. [8] Shielding film for electronic circuits comprising the lamination according to claim 1. [9] A resistance heating device comprising the lamination according to claim 1.