Single layer polymer films and electronic devices

Abstract

In a first embodiment, the single-layer polymer film comprises 60 to 99 weight% of crosslinked polyimide having a gel fraction in the range of 20 to 100% and a refractive index of 1.74 or less, and 1 to 40 weight% of a coloring agent. The surface of the single-layer polymer film is textured, and has a maximum roughness (Spv) of 6 μm or more, an L* color of 30 or less, and a 60° glossiness of 15 or less. In a second embodiment, a coverlay for a printed circuit board comprises the single-layer polymer film of the first embodiment. In third and fourth embodiments, a method for forming a single-layer polymer film comprising a crosslinked polyimide film comprising a dianhydride and a diamine is disclosed.

Description

Technology Field

[0001] The present invention relates to a single-layer polymer film, a coverlay, and an electronic device, and a method for forming the same. Background Technology

[0002] The industry is increasingly demanding that polyimide films for electronic applications be matte in appearance, possess specific colors, be durable for handling and circuit processing, and provide security against unwanted visual inspection of the electronic components protected by the coverlay when used as a coverlay. Single-layer matte gloss films do not have an L* chromaticity of less than 30, which provides the deep, rich saturation colors required by the industry. Generally, the chromaticity of the film weakens as the amount of matting agent increases. The effect of increased surface roughness by the matting agent is to dilute the pigment color, making it appear brighter and less saturated. This is due to the dilution of diffuse reflection (where the pigment color is perceived) caused by increased scattering of specular reflection (white light). The rougher the surface, the lower the gloss and the greater the scattering of specular reflection. Therefore, as gloss decreases, L* (lightness) generally increases. Adding more colorants does not reduce L* chromaticity. Consequently, it is difficult to achieve both low gloss and low L* chromaticity simultaneously. To overcome these challenges, U.S. Patents 9,469,781, 9,481,150, and 9,481,809 use a multilayer structure in which a thin polyimide layer comprising a blend of a matting agent, carbon black, and submicron particles is attached to a thicker base polyimide layer so that the multilayer film can achieve a desired combination of low L* chromaticity and low gloss.

[0003] The success of multilayer coverlays in circuit production depends on the etching thickness during pumice, desmear, and plasma processes. If a very thin outer layer of a multilayer film is used, there is a risk that the outer layer of the film will be etched during these processes, exposing the base layer, which can cause significant changes in gloss and color. Therefore, the outer layer must be sufficiently thick to withstand removal during these processes.

[0004] As electronic devices and their components become increasingly thinner and smaller, forming coverlays that possess both low gloss and low chromaticity becomes much more difficult. In some cases, the need for thinner coverlays limits the use of matting agents that can have particle sizes comparable to film thickness, as well as limiting the overall thickness of the layers in multilayer coverlays. There is a need for a single-layer polymer film that is aesthetically matte and possesses deep, rich chromatic colors, as well as acceptable electrical properties (e.g., dielectric strength), mechanical properties, and durability for handling and circuit processing, while providing sufficient optical density to offer visual security when used as a coverlay. Such films must also withstand post-processing etching processes better.

[0005] In the first embodiment, the single-layer polymer film comprises 60 to 99 wt% of cross-linked polyimide having a gel fraction in the range of 20 to 100% and a refractive index of 1.74 or less, and 1 to 40 wt% of a coloring agent. The surface of the single-layer polymer film is textured, and the maximum roughness (S pv ) is 6 μm or more, L* color is 30 or less, and 60° gloss is 15 or less.

[0006] In a second embodiment, the coverlay for the printed circuit board comprises the single-layer polymer film of the first embodiment.

[0007] In a third embodiment, a method for forming a monolayer polymer film comprising a cross-linked polyimide film comprising a dianhydride and a diamine is disclosed. The dianhydride, the diamine, or both the dianhydride and the diamine comprise an alicyclic monomer, an aliphatic monomer, or both an alicyclic monomer and an aliphatic monomer. The polymer film has an L* color value of 30 or less and a 60° gloss value of 15 or less. The cross-linked polyimide film

[0008] (a) a step of obtaining a polyamic acid solution by polymerizing a dianhydride and a diamine in the presence of a solvent;

[0009] (b) a step of imidizing a polyamic acid solution to form a substantially imidized solution;

[0010] (c) a step of adding a crosslinking agent and a coloring agent to a substantially imidized solution;

[0011] (d) substantially imidized solution at maximum roughness (S pv A step of forming a film by casting it onto a removable substrate having a textured surface having a thickness of 6 μm or more;

[0012] (e) a step of crosslinking the polyimide while drying the film; and

[0013] (f) is formed by the step of removing a single-layer polymer film from a textured substrate.

[0014] In a fourth embodiment, a method for forming a monolayer polymer film comprising a cross-linked polyimide film comprising a dianhydride and a diamine is disclosed. The dianhydride, the diamine, or both the dianhydride and the diamine comprise an alicyclic monomer, an aliphatic monomer, or both an alicyclic monomer and an aliphatic monomer. The polymer film has an L* color value of 30 or less and a 60° gloss value of 15 or less. The cross-linked polyimide film is

[0015] (a) a step of obtaining a polyamic acid solution by polymerizing a dianhydride and a diamine in the presence of a first solvent;

[0016] (b) a step of imidizing a polyamic acid solution to form a first solution substantially imidized;

[0017] (c) a step of precipitating the first solution substantially imidized using an antisolvent;

[0018] (d) a step of filtering and drying the first solution substantially imidized to obtain a solid polyimide resin;

[0019] (e) a step of dissolving a solid polyimide resin in a second solvent and adding a crosslinking agent and low-conductivity carbon black to form a second solution substantially imidized;

[0020] (f) The substantially imidized second solution at maximum roughness (S pv A step of forming a film by casting it onto a removable substrate having a textured surface having a thickness of 6 μm or more;

[0021] (g) a step of crosslinking the polyimide while drying the film; and

[0022] (h) is formed by the step of removing a single-layer polymer film from a textured substrate.

[0023] The foregoing general description and the following detailed description are merely illustrative and for illustrative purposes only and do not limit the invention as defined in the appended claims. Specific details for implementing the invention

[0024] In the first embodiment, the single-layer polymer film comprises 60 to 99 wt% of cross-linked polyimide having a gel fraction in the range of 20 to 100% and a refractive index of 1.74 or less, and 1 to 40 wt% of a coloring agent. The surface of the single-layer polymer film is textured, and the maximum roughness (S pv ) is 6 μm or more, L* color is 30 or less, and 60° gloss is 15 or less.

[0025] In one embodiment of the first aspect, the single-layer polymer film further comprises a matting agent.

[0026] In another embodiment of the first aspect, the cross-linked polyimide comprises a dianhydride selected from the group consisting of aromatic dianhydrides, aliphatic dianhydrides, and mixtures thereof. In a specific embodiment, the dianhydride is selected from the group consisting of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), cyclobutane dianhydride (CBDA), 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA), bisphenol A dianhydride (BPADA), 4,4'-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl) sulfoxide dianhydride (DSDA) and hexahydro-4,8-ethano-1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetron (BODA), and mixtures thereof.

[0027] In another embodiment of the first aspect, the crosslinked polyimide comprises a diamine selected from the group consisting of aromatic diamines, aliphatic diamines, and mixtures thereof. In a specific embodiment, the diamine is selected from the group consisting of 1,6-hexamethylenediamine (HMD), trans-1,4-diaminocyclohexane (CHDA), 3-(4-aminophenyl)-1,1,3-trimethyl-5-indamine (PIDA), isophoronediamine (IPDA), m-tolidine (MTB), 2,2'-bis(trifluoromethyl)benzidine (TFMB), m-phenylenediamine (MPD), 1,3-bis-(4-aminophenoxy)benzene (RODA), 2,2-bis-(4-[4-aminophenoxy]phenyl)propane (BAPP), and 3,4'-diaminodiphenyl ether (3,4-ODA), and mixtures thereof.

[0028] In another embodiment of the first aspect, the single-layer polymer film has a thickness in the range of 2 to 125 μm.

[0029] In another embodiment of the first aspect, the cross-linked polyimide has a refractive index of 1.69 or less.

[0030] In an additional embodiment of the first aspect, the coloring agent comprises low-conductivity carbon black.

[0031] In a second embodiment, the coverlay for the printed circuit board comprises the single-layer polymer film of the first embodiment.

[0032] In a third embodiment, a method for forming a monolayer polymer film comprising a cross-linked polyimide film comprising a dianhydride and a diamine is disclosed. The dianhydride, the diamine, or both the dianhydride and the diamine comprise an alicyclic monomer, an aliphatic monomer, or both an alicyclic monomer and an aliphatic monomer. The polymer film has an L* color value of 30 or less and a 60° gloss value of 15 or less. The cross-linked polyimide film

[0033] (a) a step of obtaining a polyamic acid solution by polymerizing a dianhydride and a diamine in the presence of a solvent;

[0034] (b) a step of imidizing a polyamic acid solution to form a substantially imidized solution;

[0035] (c) a step of adding a crosslinking agent and a coloring agent to a substantially imidized solution;

[0036] (d) substantially imidized solution at maximum roughness (S pv A step of forming a film by casting it onto a removable substrate having a textured surface having a thickness of 6 μm or more;

[0037] (e) a step of crosslinking the polyimide while drying the film; and

[0038] (f) is formed by the step of removing a single-layer polymer film from a textured substrate.

[0039] In a fourth embodiment, a method for forming a monolayer polymer film comprising a cross-linked polyimide film comprising a dianhydride and a diamine is disclosed. The dianhydride, the diamine, or both the dianhydride and the diamine comprise an alicyclic monomer, an aliphatic monomer, or both an alicyclic monomer and an aliphatic monomer. The polymer film has an L* color value of 30 or less and a 60° gloss value of 15 or less. The cross-linked polyimide film is

[0040] (a) a step of obtaining a polyamic acid solution by polymerizing a dianhydride and a diamine in the presence of a first solvent;

[0041] (b) a step of imidizing a polyamic acid solution to form a first solution substantially imidized;

[0042] (c) a step of precipitating the first solution substantially imidized using an antisolvent;

[0043] (d) a step of filtering and drying the first solution substantially imidized to obtain a solid polyimide resin;

[0044] (e) a step of dissolving a solid polyimide resin in a second solvent and adding a crosslinking agent and low-conductivity carbon black to form a second solution substantially imidized;

[0045] (f) The substantially imidized second solution at maximum roughness (S pv A step of forming a film by casting it onto a removable substrate having a textured surface having a thickness of 6 μm or more;

[0046] (g) a step of crosslinking the polyimide while drying the film; and

[0047] (h) is formed by the step of removing a single-layer polymer film from a textured substrate.

[0048] In one embodiment of the method of the fourth aspect, after step (e) and before step (f), the substantially imidized second solution is filtered to remove the insoluble components of the solution.

[0049] In another embodiment of the method of the fourth aspect, the first solvent and the second solvent are the same or different.

[0050] Although many aspects and embodiments have been described above, they are merely illustrative and not limiting. After reading this specification, those skilled in the art will understand that other aspects and embodiments are possible without departing from the scope of the invention. Other features and advantages of the invention will become apparent from the following detailed description and claims.

[0051] In one embodiment, a single-layer polymer film having a cross-linked polyimide can form a very thin coverlay that is more resistant to etching than a film using a conventional coverlay material. Using a soluble polyimide that is cross-linked after film formation produces a single-layer polymer film with improved chemical resistance that maintains the low L* color and low gloss characteristics required for such films.

[0052] Depending on the context, "diamine" as used herein means (i) an unreacted form (i.e., a diamine monomer), (ii) a partially reacted form (i.e., a portion or parts of an oligomer or other polymer precursor derived from or attributed thereto a diamine monomer), or (iii) a fully reacted form (a portion or parts of a polymer derived from or attributed thereto a diamine monomer). The diamine may be functionalized into one or more moieties according to specific embodiments selected in practice of the invention.

[0053] In practice, the term "diamine" is not limited (or interpreted literally) to the number of amine moietyes within the diamine component. For example, (ii) and (iii) above include polymeric materials that may have two, one, or zero amine moietyes. Alternatively, the diamine may be functionalized into additional amine moietyes (in addition to the monomer-terminal amine moiety that reacts with the dianhydride to propagate the polymer chain). These additional amine moietyes may be used to crosslink the polymer or to provide other functional groups to the polymer.

[0054] Similarly, the term “anhydride” as used herein refers to a component capable of reacting with a diamine (which is complementary to the diamine) and reacting in combination to form an intermediate (which can subsequently be cured into a polymer). Depending on the context, the term “anhydride” as used herein may refer not only to the anhydride moiety itself but also to a precursor of the anhydride moiety, such as (i) a pair of carboxylic acid groups (which can be converted to anhydrides by dehydration or similar types of reactions), or (ii) an acid halide (e.g., chloride) ester functional group convertible to an anhydride functional group (or any other functional group currently known or to be developed in the future that can be converted to an anhydride functional group).

[0055] Depending on the context, "anhydride" may mean (i) an unreacted form (i.e., a dianhydride monomer regardless of whether the anhydride functional group is in the true anhydride form or the precursor anhydride form as described in the previous paragraph), (ii) a partially reacted form (i.e., a portion or parts of an oligomer or other partially reacted or precursor polymer composition reacted from or derived therefrom a dianhydride monomer), or (iii) a fully reacted form (a portion or parts of a polymer derived from or derived therefrom a dianhydride monomer).

[0056] The dianhydride may be functionalized into one or more moiety according to specific embodiments selected in practice of the present invention. In practice, the term “dianhydride” is not limited (or interpreted literally) to the number of anhydride moietyes within the dianhydride component. For example, (i), (ii), and (iii) (of the paragraph above) include organic materials that may have two, one, or zero anhydride moietyes depending on whether the anhydride is in a precursor state or a reacted state. Alternatively, the dianhydride component may be functionalized into additional types of anhydride moietyes (in addition to the anhydride moiety that reacts with the diamine to provide the polymer). These additional anhydride moietyes may be used to crosslink the polymer or to provide other functional groups to the polymer.

[0057] Any one of the many polyimide manufacturing processes may be used to manufacture a single-layer polymer film. It would be impossible to discuss or describe all possible manufacturing processes useful for carrying out the present invention. It should be understood that the monomer system of the present invention can provide the aforementioned advantageous properties in various manufacturing processes. The composition of the present invention may be manufactured as described herein and may be readily manufactured by any of the many (perhaps numerous) ways of those skilled in the art using any conventional or unconventional manufacturing technique.

[0058] Methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention, but suitable methods and materials are described herein.

[0059] Where a quantity, concentration, or other value or parameter is given as a range, a preferred range, or a list of preferred upper and lower limits, it should be understood that this specifically discloses any range formed from any pair of any upper or preferred value and any lower or preferred value, regardless of whether the range is disclosed separately. Where numerical ranges are cited herein, unless otherwise specified, the range means both ends and all integers and fractions within the range. The scope of the invention is not limited to the specific values ​​mentioned when defining a range.

[0060] In describing a specific polymer, it should be understood that the applicant sometimes refers to the polymer by the monomer used to manufacture the polymer or by the amount of monomer used to manufacture the polymer. While such descriptions may not include specific nomenclature used to describe the final polymer or may not include terms of the invention that limit the preparation method, any such references to monomers and amounts should be interpreted to mean that the polymer is prepared from these monomers or amounts of monomers, and the corresponding polymer and its composition.

[0061] The materials, methods, and examples of the present invention are merely illustrative and are not limiting, except where specifically stated.

[0062] As used herein, the terms “include,” “includes,” “have,” “have,” or any other variations thereof mean non-exclusive inclusion. For example, a method, process, article, or device including a list of elements is not necessarily limited to such elements alone, but may include other elements unique to such method, process, article, or device or not explicitly enumerated. Also, unless explicitly stated otherwise, “or” means inclusive disjunction rather than exclusive disjunction. For example, condition A or B is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0063] Additionally, the singular form is used to describe the elements and components of the present invention. This is merely for convenience and to provide a general meaning of the invention. This description should be understood to include one or at least one, and the singular includes the plural unless it is evident otherwise.

[0064] Organic solvent

[0065] An organic solvent useful for synthesizing the polymer of the present invention is preferably capable of dissolving a polymer precursor material. Such a solvent should also have a relatively low boiling point, e.g., below 225°C, so that the polymer can be dried at a suitable (i.e., simpler and less expensive) temperature. A boiling point below 210, 205, 200, 195, 190, or 180°C is preferred.

[0066] The solvent of the present invention may be used alone or in combination with other solvents (i.e., co-solvents). Useful solvents include N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), N,N'-dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), tetramethyl urea (TMU), diethylene glycol diethyl ether, 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglame), 1,2-bis-(2-methoxyethoxy)ethane (triglame), bis[2-(2-methoxyethoxy)ethyl)] ether (tetraglame), gamma-butyrolactone, and bis-(2-methoxyethyl) ether, tetrahydrofuran. In one embodiment, preferred solvents include N-methylpyrrolidone (NMP) and dimethylacetamide (DMAc).

[0067] The co-solvent can generally be used in an amount of about 5 to 50 weight percent of the total solvent, and useful such co-solvents include xylene, toluene, benzene, "cellosolve" (glycol ethyl ether), and "cellosolve acetate" (hydroxyethyl acetate glycol monoacetate).

[0068] diamine

[0069] In one embodiment, the diamine suitable for forming the polyimide may include aliphatic diamines, such as 1,2-diaminoethane, 1,6-diaminohexane (HMD), 1,4-diaminobutane, 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. Other aliphatic diamines suitable for carrying out the present invention include those having 6 to 12 carbon atoms, or a combination of longer-chain and shorter-chain diamines as long as both developability and flexibility are maintained. Long-chain aliphatic diamines increase flexibility.

[0070] In one embodiment, the diamine suitable for forming the polyimide is a fluorinated aromatic diamine, such as 2,2'-bis(trifluoromethyl)benzidine (TFMB), trifluoromethyl-2,4-diaminobenzene, trifluoromethyl-3,5-diaminobenzene, 2,2'-bis-(4-aminophenyl)-hexafluoropropane, 4,4'-diamino-2,2'-trifluoromethyl diphenyloxide, 3,3'-diamino-5,5'-trifluoromethyl diphenyloxide, 9.9'-bis(4-aminophenyl)fluorene, 4,4'-trifluoromethyl-2,2'-diaminobiphenyl, 4,4'-oxy-bis-[2-trifluoromethyl)benzeneamine](1,2,4-OBABTF), 4,4'-oxy-bis-[3-trifluoromethyl)benzeneamine], 4,4'-thio-bis-[(2-trifluoromethyl)benzene-amine], 4,4'-thiobis[(3-trifluoromethyl)benzene amine], 4,4'-sulfoxyl-bis-[(2-trifluoromethyl)benzene amine, 4,4'-sulfoxyl-bis-[(3-trifluoromethyl)benzene amine], 4,4'-keto-bis-[(2-trifluoromethyl)benzene amine], 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; It may further comprise 1,4-(2'-trifluoromethyl-4',4"-diaminodiphenoxy)-benzene, 1,4-bis(4'-aminophenoxy)-2-[(3',5'-ditrifluoromethyl)phenyl]benzene, 1,4-bis[2'-cyano-3'("4-aminophenoxy)phenoxy]-2-[(3',5'-ditrifluoro-methyl)phenyl]benzene (6FC-diamine), 3,5-diamino-4-methyl-2',3',5',6'-tetrafluoro-4'-tri-fluoromethyldiphenyloxide, 2,2-bis[4'(4"-aminophenoxy)phenyl]phthalein-3',5'-bis(trifluoromethyl)anilide (6FADAP), and 3,3',5,5'-tetrafluoro-4,4'-diamino-diphenylmethane (TFDAM). Specific In an embodiment, the fluorinated diamine is 2,2'-bis(trifluoromethyl)benzidine (TFMB).In one embodiment, the fluorinated aromatic diamine may be present in a range of 40 to 95 mol% based on the total diamine content of the polyimide. In a more specific embodiment, the fluorinated aromatic diamine may be present in a range of 50 to 75 mol% based on the total diamine content of the polyimide.

[0071] In one embodiment, p-phenylenediamine (PPD), m-tolidine (MTB), m-phenylenediamine (MPD), 3-(4-aminophenyl)-1,1,3-trimethyl-5-indaneamine (PIDA), 2,5-dimethyl-1,4-diaminobenzene, 2,5-dimethyl-1,4-phenylenediamine (DPX), 2,2-bis-(4-aminophenyl)propane, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 4,4'-diaminobiphenyl, 4,4'-diaminoterphenyl, 4,4'-diaminobenzanilide, 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-(aminophenoxy)biphenyl (BAPB), 4,4'-Diaminodiphenyl ether (ODA), 3,4'-Diaminodiphenyl ether (3,4-ODA), 4,4'-Diaminobenzophenone, 4,4'-Isopropylidenedianiline, 2,2'-Bis-(3-aminophenyl)propane, N,N-Bis-(4-aminophenyl)-n-butylamine, N,N-Bis-(4-aminophenyl)methylamine, 1,5-Diaminonaphthalene, 3,3'-Dimethyl-4,4'-Diaminobiphenyl, m-aminobenzoyl-p-aminoanilide, 4-aminophenyl-3-aminobenzoate, N,N-Bis-(4-aminophenyl) Several additional diamines, including aniline, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 2,4-diamine-5-chlorotoluene, 2,4-diamine-6-chlorotoluene, 2,4-bis-(beta-amino-t-butyl)toluene, bis-(p-beta-amino-t-butylphenyl)ether, p-bis-2-(2-methyl-4-aminopentyl)benzene, m-xylylene diamine, and p-xylylene diamine, can be used to form polyimides.

[0072] Other useful diamines are 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, 2,4,6-trimethyl-1,3-diaminobenzene, and It contains 2,4,6-trimethyl-1,3-diaminobenzene.

[0073] Imusumul

[0074] In one embodiment, several suitable dianhydrides may be used to form the polyimide. The dianhydride may be used in the form of tetraacid (or as a mono, di, tri, or tetraester of tetraacid) or as a diesteric acid halide (chloride). However, in some embodiments, the dianhydride form may be preferred because it is generally more reactive than the acid or ester.

[0075] Examples of suitable dianhydrides are 3,3',4,4'-biphenyl tetracarboxylic acid dianhydride (BPDA), 1,2,5,6-naphthalene tetracarboxylic acid dianhydride, 1,4,5,8-naphthalene tetracarboxylic acid dianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride, 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'-benzophenone tetracarboxylic acid dianhydride, 2,3,3',4'-Benzophenone tetracarboxylic acid dianhydride, 3,3',4,4'-Benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2',3,3'-Biphenyl tetracarboxylic acid dianhydride, 2,3,3',4'-Biphenyl tetracarboxylic acid dianhydride, Bicyclo-[2,2,2]-octene-(7)-2,3,5,6-tetracarboxylic acid-2,3,5,6-dianhydride, 4,4'-Thio-diphthalic anhydride, Bis (3,4-Dicarboxyphenyl)sulfone dianhydride, Bis (3,4-Dicarboxyphenyl)sulfoxide dianhydride (DSDA), Bis (3,4-Dicarboxyphenyl oxadiazole-1,3,4) p-phenylene dianhydride, Bis (3,4-Dicarboxyphenyl) 2,5-Oxadiazole 1,3,4-Dianhydride, Bis 2,5-(3',4'-Dicarboxydiphenyl Ether) 1,3,4-Oxadiazole Dianhydride, 4,4'-Oxydiphthalic Anhydride (ODPA), Bis (3,4-Dicarboxyphenyl) Thio Ether 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, Cyclopentadienyl Tetracarboxylic Acid Dianhydride, Cyclopentane Tetracarboxylic Acid Dianhydride, Ethylene Tetracarboxylic Acid Dianhydride, Perylene 3,4,9,10-tetracarboxylic acid dianhydride, pyromellitic acid dianhydride (PMDA), tetrahydrofuran tetracarboxylic acid dianhydride, 1,3-bis-(4,4'-oxydiphthalic anhydride) benzene, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,6-dichloronaphthalene-1,4,Includes 5,8-tetracarboxylic acid dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, benzene-1,2,3,4-tetracarboxylic acid dianhydride, and thiophene-2,3,4,5-tetracarboxylic acid dianhydride.

[0076] In one embodiment, suitable dianhydrides may include cyclobutane dianhydrides, such as cyclohexane dianhydride (CBDA), cyclohexane dianhydride, 1,2,3,4-cyclopentane tetracarboxylic acid dianhydride (CPDA), hexahydro-4,8-ethano-1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetron (BODA), 3-(carboxymethyl)-1,2,4-cyclopentane tricarboxylic acid 1,4:2,3-dianhydride (TCA), and meso-butane-1,2,3,4-tetracarboxylic acid dianhydride.

[0077] In one embodiment, the dianhydrides suitable for forming the polyimide may include fluorinated dianhydrides, such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 9,9-bis(trifluoromethyl)-2,3,6,7-xanthen tetracarboxylic acid dianhydride.

[0078] crosslinking agent

[0079] In one embodiment, a crosslinking agent may be used in the polymer film. By crosslinking the polyimide, the polymer film can have improved mechanical properties as well as improved chemical resistance. Crosslinking agents include polyetheramines such as Jeffamine® D-230, Jeffamine® D-400, Jeffamine® D-2000, Jeffamine® D-2010, Jeffamine® D-4000, Jeffamine® ED-600, Jeffamine® ED-900, Jeffamine® D-2003, Jeffamine® EDR-148, Jeffamine® THF-100, Jeffamine® THF-170, Jeffamine® SD-2001, Jeffamine® D-205, and Jeffamine® RFD-270, piperazine, secondary amines such as N,N'-diisopropylethylenediamine, N,N'-diisopropyl-1,3-propanediamine, and N,N'-dimethyl-1,3-propanediamine, and 2,4,6-triaminopyrimidine (TAP), melamine, diethylenetriamine, Jeffamine® T-403, It may include triamines such as Jeffamine® T-3000 and Jeffamine® T-5000. In addition, many diamines that can be used as diamine monomers for polyimides as described above may also be useful as crosslinking agents.

[0080] coloring agent

[0081] In one embodiment, the polymer film contains about 1 to about 40 wt% of a coloring agent, such as a pigment or dye. In some embodiments, the polymer film contains about 1 to about 40 wt% of a mixture of pigment and dye. In some embodiments, the polymer film contains a coloring agent in a range between any two values ​​(including both ends) of 1, 5, 10, 15, 20, 25, 30, 35, and 40 wt%.

[0082] Almost any pigment (or combination of pigments) can be used to carry out the present invention. In some embodiments, useful pigments include, but are not limited to, barium lemon yellow, cadmium yellow lemon, cadmium yellow lemon, cadmium yellow light, cadmium yellow middle, cadmium yellow orange, scarlet lake, cadmium red, cadmium vermilion, alizarin crimson, permanent magenta, van Dyke brown, raw umber greenish, or burnt umber. In some embodiments, useful black pigments include cobalt oxide, Fe-Mn-Bi black, Fe-Mn oxide spinel black, (Fe,Mn)2O3 black, copper chromite black spinel, lamp black, bone char, bone ash, bone carbide, hematite, black iron oxide, mica-like iron oxide, black composite inorganic colored pigment (CICP), (Ni,Mn,Co)(Cr,Fe)2O4 black, aniline black, perylene black, anthraquinone black, chrome green-black hematite, chrome iron oxide, pigment green 17, pigment black 26, pigment black 27, pigment black 28, pigment brown 29, pigment brown 35, pigment black 30, pigment black 32, pigment black 33, or mixtures thereof.

[0083] In some embodiments, the pigment is lithopone, zinc sulfide, barium sulfate, cobalt oxide, yellow iron oxide, orange iron oxide, red iron oxide, brown iron oxide, hematite, black iron oxide, mica-like iron oxide, chrome(III) green, ultramarine blue, ultramarine violet, ultramarine pink, cyanide blue, cadmium pigment, or lead chromate pigment.

[0084] In some embodiments, the pigment is a composite inorganic colored pigment (CICP), such as spinel pigment, rutile pigment, zircon pigment, or bismuth vanadate yellow. In some embodiments, useful spinel pigments include, but are not limited to, Zn(Fe,Cr)2O4 brown, CoAl2O4 blue, Co(AlCr)2O4 blue-green, Co2TiO4 green, CuCr2O4 black, or (Ni,Mn,Co)(Cr,Fe)2O4 black. In some embodiments, useful rutile pigments include, but are not limited to, Ti-Ni-Sb yellow, Ti-Mn-Sb brown, Ti-Cr-Sb buff, zircon pigment, or bismuth vanadate yellow.

[0085] In other embodiments, the pigment is an organic pigment. In some embodiments, useful organic pigments include, but are not limited to, aniline black (pigment black 1), anthraquinone black, monoazo, diazo, benzimidazolone, diallylide yellow, monoazo yellow salt, dinitroaniline orange, pyrazolone orange, azo red, naphthol red, azo condensation pigment, lake pigment, copper phthalocyanine blue, copper phthalocyanine green, quinacridone, diallyl pyrrolopyrrole, aminoanthraquinone pigment, dioxazine, isoindolinone, isoindoline, quinophthalone, phthalocyanine pigment, indantron pigment, pigment violet 1, pigment violet 3, pigment violet 19, or pigment violet 23. In another embodiment, the organic pigment is a vat dye pigment such as (but not limited to) perylene, perylene black, perinone, or thioindigo. Uniform dispersion of isolated individual pigment particles (aggregates) tends to produce uniform color intensity. In some embodiments, the pigment is milled. In some embodiments, the average particle size of the pigment is in the range between any two values ​​of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 μm (optional including both ends). In some embodiments, the luminescent (fluorescent or phosphorescent) or pearlescent pigment may be used alone or in combination with other pigments or dyes.

[0086] In one embodiment, the coloring agent may comprise low-conductivity carbon black. In some embodiments, the coloring agent comprises low-conductivity carbon black in a range between any two values ​​of 1, 5, 10, 15, and 20 wt% (including both ends). In another embodiment, the coloring agent comprises about 2 to about 9 wt% of low-conductivity carbon black.

[0087] Low-conductivity carbon black refers to channel black, furnace black, or lamp black. In some embodiments, low-conductivity carbon black is surface-oxidized carbon black. One method to evaluate the degree of surface oxidation (of carbon black) is to measure the volatile content of the carbon black. The volatile content can be measured by calculating the weight loss upon calcination at 950°C for 7 minutes. Generally speaking, highly surface-oxidized carbon black (high volatile content) can be easily dispersed in a polyamic acid solution (polyimide precursor), which can eventually be imidized into the (well-dispersed) charged polyimide-based polymer of the present invention. It is generally believed that if carbon black particles (aggregates) do not come into contact with each other, electron tunneling, electron hopping, or other electron flow mechanisms are suppressed, resulting in lower electrical conductivity. In some embodiments, low-conductivity carbon black has a volatile content of 1% or more. In some embodiments, the low-conductivity carbon black has a volatile component content of 5, 9, or 13% or more. In some embodiments, the furnace black may be surface-treated to increase the volatile component content. Generally, the low-conductivity carbon black has a pH of about 6 or less.

[0088] Uniform dispersion of isolated carbon black particles (aggregates) tends not only to reduce electrical conductivity but also to produce uniform color intensity. In some embodiments, the low-conductivity carbon black is milled. In some embodiments, the average particle size of the low-conductivity carbon black is in the range between any two values ​​of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 μm (optional including both ends).

[0089] Matting agent

[0090] In one embodiment, the polymer film contains about 0.5 to about 20 wt% of a matting agent selected from the group consisting of silica, alumina, zirconia, boron nitride, barium sulfate, polyimide particles, calcium phosphate, talc, or mixtures thereof. In some embodiments, the polymer film contains a matting agent in a range between any two values ​​of 0.5, 1, 5, 10, 15, and 20 wt% (including both ends). In one embodiment, the matting agent has a particle size in the range of about 2 to about 10 μm, or about 3 to about 9 μm, or about 5 or about 7 μm.

[0091] submicron particles

[0092] In one embodiment, the polymer film contains at least one submicron particle, such as a submicron dry metal oxide (also known as an exothermic metal oxide) or a submicron colloidal metal oxide, or a mixture thereof, in an amount of up to about 39 wt%. In some embodiments, the submicron dry metal oxide is dry alumina, dry silica, or a mixture thereof. The addition of submicron dry metal oxides surprisingly reduces the amount of coloring agent (e.g., submicron carbon black) required to produce a polymer film with an L* color value of less than about 30. Since submicron dry alumina and dry silica in PI films are, by themselves, sometimes white or cloudy, it was not predicted that the amount of coloring agent required to produce deep and rich colors would actually be lowered by the addition of these dry oxides. Also, surprisingly, other submicron metal oxides do not have the same effect. In one embodiment, the polymer film comprises at least one submicron particle of up to about 20 wt% or up to about 10 wt%. In one embodiment, the submicron particles have a particle size of less than about 1 μm. In one embodiment, the submicron particles have a particle size in the range of about 0.01 to about 1 μm, or about 0.05 to about 0.5 μm.

[0093] The particle sizes of submicron particles, carbon black, and matting agents can be measured in the slurry by laser diffraction using a particle size analyzer such as the LA-930 (Horiba, Instruments, Inc., Irvine, CA), Mastersizer 3000 (Malvern Instruments, Inc., Westborough, MA), or LS-230 (Beckman Coulter, Inc., Indianapolis, IN). However, due to the tendency of submicron particles to aggregate, it is sometimes more accurate to measure the particle size of such milled slurries by observing them with an optical microscope.

[0094] Single-layer polymer film

[0095] As used herein, the term “single-layer polymer film” means a layer of polymer film having an essentially homogeneous composition throughout the layer such that the monomer used to form the polymer is present throughout the thickness of the layer and any filler, such as a matting agent, carbon black, and submicron particles, is also distributed throughout the thickness of the layer. Although a single-layer polymer film is essentially homogeneous, it may exhibit slight stepwise variations in the composition of the layer over a certain region or thickness, particularly at the surface of the film. Conversely, a polymer film having distinct variations in composition over a certain region or thickness of the film will not be a single-layer polymer film. For example, a polyimide film having a core layer of one composition and an outer layer of a different composition (e.g., a different monomer used to form the polymer of the outer layer or a different filler of the outer layer) will not be a single-layer polymer film.

[0096] In one embodiment, the single-layer polymer film may comprise a polyimide that can be produced by combining a diamine and a dianhydride (in the form of a monomer or other polyimide precursor) with a solvent to form a polyamic acid (also called a polyamic acid) solution. The dianhydride and the diamine may be combined in a molar ratio of about 0.90 to about 1.10. The molecular weight of the polyamic acid formed therefrom can be adjusted by adjusting the molar ratio of the dianhydride and the diamine.

[0097] A useful method for manufacturing a polymer film containing polyimide includes the following:

[0098] (a) A method of mixing the diamine component and the dianhydride component together beforehand and then adding the mixture little by little while stirring it in a solvent.

[0099] (b) A method of adding a solvent to a stirred mixture of a diamine component and a dianhydride component (opposite to (a) above).

[0100] (c) A method of dissolving a diamine alone in a solvent and then adding a dianhydride in a ratio that can control the reaction rate.

[0101] (d) A method of dissolving a dianhydride component alone in a solvent and then adding an amine component in a ratio that controls the reaction rate.

[0102] (e) A method of dissolving the diamine component and the dianhydride component individually in a solvent and then mixing these solutions in a reactor.

[0103] (f) A method of forming a polyamic acid with an excess of amine component and another polyamic acid with an excess of dianhydride component in advance, and then reacting them with each other in a reactor in a manner that produces a non-random or block copolymer.

[0104] (g) A method of reacting a specific portion of the amine component with the dianhydride component first, and then reacting the remaining diamine component, or vice versa.

[0105] (h) A method of adding components to part or all of a solvent in any order, either partially or wholly, and also adding any component to part or all of the solvent as a solution.

[0106] (i) a method of first reacting one of the dianhydride components with one of the diamine components to provide a first polyamic acid, then reacting another dianhydride component with another amine component to provide a second polyamic acid, and then combining the amic acid in any one of the following ways.

[0107] In one embodiment, the polyamic acid solution may be combined with the following conversion chemicals: (i) one or more dehydrating agents, e.g., aliphatic acid anhydrides (acetic anhydrides, etc.) and / or aromatic acid anhydrides; and (ii) one or more catalysts, e.g., aliphatic tertiary amines (triethylamine, etc.), aromatic tertiary amines (dimethylaniline, etc.), and heterocyclic tertiary amines (pyridine, alpha, beta, and gamma picoline (2-methylpyridine, 3-methylpyridine, 4-methylpyridine), isoquinoline, etc.). The anhydride dehydrating agent is typically used in an excess molar amount relative to the amount of amic acid groups in the polyamic acid. The amount of acetic anhydride used is generally about 2.0 to about 4.0 moles per equivalent (repeating unit) of the polyamic acid. Generally, a similar amount of tertiary amine catalyst is used.

[0108] In one embodiment, the conversion chemical may be an imidation catalyst. The use of an imidation catalyst can help lower the imidation temperature and shorten the imidation time. Common imidation catalysts may be bases, such as imidazole, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, benzimidazole, isoquinoline, or substituted pyridines, such as methylpyridine, rutidine, and trialkylamines. A combination of tertiary amines and acid anhydrides may be used. Such dehydrating agents that can act as co-catalysts include acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, etc. The ratio and concentration of these catalysts in the polyamic acid solution will affect the imidation reaction rate.

[0109] In one embodiment, the polyamic acid solution may be converted into polyimide by heating, if necessary, in the presence of an imidation catalyst to partially or completely imidize the polyamic acid. Temperature, time, and the concentration and selection of the imidation catalyst may affect the degree of imidization of the polyamic acid solution. Preferably, the solution should be substantially imidized. In one embodiment, for a substantially imidized polyimide solution, more than about 85%, more than about 90%, or more than about 95% of the amic acid groups are converted into polyimide when measured by infrared spectroscopy.

[0110] In one embodiment, a substantially imidized polyimide solution is formed using monomers (diamines or dianhydrides) having structural properties important to solubility, including aliphatic spacers, flexible linkers such as (but not limited to) ethers, thioethers, substituted amines, amides, esters, and ketones, weak intermolecular interactions, bulk substitution, non-coplanarity, nonlinearity, and asymmetry. Examples of diamines having some of these properties are aliphatic diamines such as HMD, CHDA, and IPDA, and aromatic diamines such as MTB TFMB, MPD, RODA, BAPP, and 3,4-ODA. Examples of dianhydrides having some of these properties are 6FDA, BPADA, ODPA, DSDA, and BODA.

[0111] In one embodiment, the solvated mixture (a substantially imidized solution) may be mixed with a crosslinking agent and a coloring agent, such as a pigment or dye, and then cast to form a single-layer polyimide film. In one embodiment, the coloring agent may be low-conductivity carbon black. In another embodiment, the solvated mixture (a first substantially imidized solution) may be precipitated using water or an antisolvent such as an alcohol (e.g., methanol, ethanol, isopropyl alcohol). In one embodiment, the precipitate may be washed to remove the catalyst. After washing, the precipitate may be substantially dried, but does not need to be completely dried. The polyimide precipitate may be redissolved in a second solvent such as methyl isobutyl ketone (MIBK), methyl ethyl ketone (MEK), tetrahydrofuran (THF), cyclopentanone, ethyl acetate, acetone, DMAc, NMP, and mixtures thereof to form a substantially imidized second solution (casting solution). A crosslinking agent and a coloring agent may be added to the substantially imidized second solution, and then cast to form a single-layer polymer film. In one embodiment, the single-layer polymer film contains crosslinked polyimide in the range of about 80 to about 99 wt%. In some embodiments, the polymer film contains crosslinked polyimide in the range between any two values ​​of 80, 85, 90, 95, and 99 wt% (including both ends). In another embodiment, the polymer film contains about 91 to about 98 wt% crosslinked polyimide.

[0112] The crosslinking of polyimide can be confirmed by various methods. In one embodiment, the gel fraction of the polyimide can be measured by comparing the weight of the dried film before and after crosslinking using an equilibrium swelling method. In one embodiment, the crosslinked polyimide may have a gel fraction in the range of about 20 to about 100%, or about 40 to about 100%, or about 50 to about 100%, or about 70 to about 100%, or about 85 to about 100%. In one embodiment, the crosslinked network can be confirmed using a rheological method. The formation of the crosslinked network can be confirmed using oscillatory time sweep measurements at specific strain, frequency, and temperature. Initially, the loss modulus (G") value is higher than the storage modulus (G') value, indicating that the polyimide solution behaves like a viscous liquid. Over time, the formation of a cross-linked polyimide network is evidenced by the intersection of the G' and G" curves. This intersection, referred to as the "gel point," marks the point where the elastic component predominates over the viscous component and the polymer begins to behave like an elastic solid.

[0113] In one embodiment, a substantially imidized polyimide solution may be cast or applied onto a support, such as a circulating belt or a rotating drum, to form a film. Alternatively, the solution may be cast onto a polymer carrier, such as a polyethylene terephthalate (PET) film, other forms of Kapton® polyimide films (e.g., Kapton® HN or Kapton® OL films), or other polymer carriers. In one embodiment, the support or carrier layer may be textured, such as a textured PET substrate. Subsequently, the substantially imidized solution may be converted into a film by crosslinking the polyimide by heating and partially or completely removing the solvent. To initiate polyimide crosslinking and partially dry the polyimide film, the film is heated at a low temperature. Generally, a temperature of about 100°C or less is used for initial drying and crosslinking. Subsequently, to complete polyimide crosslinking and further remove the solvent, the film is heated to a higher temperature of up to about 300°C. In some embodiments of the present invention, the film is separated from the carrier before drying is completed. The final drying step may be performed while maintaining the dimensions of the film. In other embodiments, the film is heated directly on the carrier.

[0114] In one embodiment, the single-layer polymer film comprises a polyimide having a low refractive index, such as less than about 1.74, less than about 1.69, or less than about 1.60. Lowering the refractive index of the polyimide allows for the formation of a single-layer polymer film with both low L* and low gloss. Conventional polyimides exhibit a significantly higher refractive index (RI) than other common optical polymers due to a higher content of aromatic rings and imide structures. However, poor transparency in the visible region poses a serious obstacle to light trapping, increasing reflection at the film surface. Light absorption by polyimides in the visible region occurs primarily due to intramolecular and intermolecular charge transfer (CT) interactions between electron-donating diamine moiety and electron-accepting dianhydride moiety. In one embodiment, the average refractive index n of the material av It can be estimated by the following Lorenz-Lorenz equation.

[0115]

[0116] Among foods, α av is the average molecular polarization, and V int is the eigenvol of the repeating unit, ρ is the density, and N A ε₀ is Avogadro's number, and M is the molecular weight. This formula can be simplified as follows.

[0117]

[0118] During the meal, K p is the molecular packing coefficient and V vdw is the molecular van der Waals volume (Reference [Y. Terui and S. Ando, J Polym Sci: Part B Polymer Physics, [Refer to 42, 2354-2366 (2004)]). Based on this equation, one method to minimize the refractive index of a polymer formulation is α av / V vdwThe goal is to minimize the contribution of the ratio. This ratio variable can be calculated empirically, semi-empirically, or from the first principles. Using this calculated ratio, monomers can be selected or removed with the goal of achieving a low refractive index. The objective is to lower the refractive index of the polymer by reducing the polarization of the polyimide molecular chains. The polarization of the polymer can be reduced by the introduction of electron-attracting fluorine atoms or fluorinated substituents, the incorporation of alicyclic moiety, and modification of the molecular backbone by meta-substitution structures and bulk side chains.

[0119] In one embodiment, the single-layer polymer film may have an L* of about 30 or less and a 60° gloss of about 15 or less. In one embodiment, the single-layer polymer film may have an L* of about 25 or less or about 20 or less. In one embodiment, the single-layer polymer film may have a 60° gloss of about 10 or less or about 8 or less or about 6 or less.

[0120] The thickness of the single-layer polymer film can be adjusted according to the intended purpose or final application specifications of the film. In one embodiment, the single-layer polymer film has a total thickness in the range of about 2 to about 125 μm, or about 4 to about 50 μm, or about 5 to about 20 μm.

[0121] In one embodiment, a single-layer polymer film may be textured using mechanical or chemical means. In one embodiment, mechanical texture treatment may include a process of physically removing a portion of the film surface, such as sandblasting or laser ablation. In one embodiment, in the case of sandblasting, the single-layer polymer film may be textured by spraying fine sand onto the film surface in an abrasive-blasting (centrifugal-blasting) process in which a rotating impeller sprays sand using centrifugal force. In one embodiment, texture treatment may be provided by embossing or imprinting a texture onto the film surface. In one embodiment, in the case of imprinting, the single-layer polymer film may be textured by casting the film onto a textured surface so that the texture is transferred to the surface of the polymer film. In one embodiment, chemical texture treatment may be provided through lithography.

[0122] In one embodiment, the textured film may have both low L* chromaticity and low gloss even if the film does not contain a matting agent. In one embodiment, a single-layer polymer film having a textured surface has a maximum roughness (S) of about 6 μm or more. pv It may have an L* of about 30 or less, and a 60° glossiness (60GU) of about 15 or less. In one embodiment, the single-layer polymer film having a textured surface has an S of about 7 μm or more or about 8 μm or more. pv It may have. In one embodiment, a single-layer polymer film having a textured surface may have an L* of about 25 or less or about 20 or less. In one embodiment, a single-layer polymer film having a textured surface may have a 60° glossiness of about 10 or less, about 8 or less, or about 6 or less. In one embodiment, both sides of the single-layer polymer film may have a textured surface.

[0123] Applications

[0124] In one embodiment, a single-layer polymer film is used in electronic device applications, such as a coverlay for a printed circuit board or other electronic components of an electronic device, to provide protection from physical damage, oxidation, and other contaminants that may adversely affect the function of the electronic components. A very thin coverlay of a single-layer polymer film using cross-linked polyimide has superior chemical resistance and can withstand etching during pumice, desmear, and plasma processes used in circuit production while maintaining excellent optical properties.

[0125] The advantageous features of the present invention can be understood by referring to the following examples, which illustrate but do not limit the invention. Unless otherwise specified, all parts and percentages are by weight.

[0126] Examples

[0127] Test method

[0128] CIE L*, a*, b* chromaticity

[0129] Chromaticity measurements were performed using a ColorQuest® XE dual-beam spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA) in specular reflection mode. The instrument was standardized before each use. The chromaticity data measured by the instrument was recorded as L*, a*, and b* on the CIELAB 10° / D65 system. An L* value of 0 is pure black, and an L* value of 100 is pure white. Generally, a difference of 1 unit in L* value is discernible to the naked eye.

[0130] Refractive index

[0131] Refractive index measurements were performed using a Metricon® Model 2010 Prism Coupler (Metricon Corporation, Pennington, NJ) utilizing a laser wavelength of 633 nm (632.8 nm). The instrument was referenced before each use. Refractive index measurements were performed in transverse electric field mode to record the refractive index in the plane of the film.

[0132] Gel fraction

[0133] The polyimide gel fraction was measured using the Soxhlet extraction method. A polymer film sample was placed in a glass thimble positioned in the main chamber of a Soxhlet extractor, which was placed over a nitrogen-purged, solvent-filled round-bottom flask. The extraction solvent (DMAc) was continuously circulated through the sample by boiling and condensation. After applying sufficient heat to the round-bottom flask, the solvent in vapor form was transferred to the main chamber of the Soxhlet extractor for condensation. Upon reaching the overflow level, the solvent was discharged back into the round-bottom flask through a siphon tube.

[0134] A polymer film of approximately 2 x 3 inches was used. The film sample was cleaned with acetone, air-dried, weighed, and creased before being placed in a glass thimble. The temperature of DMAc (approx. 300 ml) was set to 165–175°C, and extraction was performed for at least 7 hours. Afterward, the sample was retrieved from the apparatus, dried on a 50°C hot plate for up to 1 hour, and placed in a 120°C furnace. The furnace was heated from 120°C to 250°C (16°C / min) and maintained at 250°C for 20 minutes. After heating at 250°C for 20 minutes, the film was removed from the oven while "hot," cooled in the air, and the sample was weighed again. A new solvent was used for each sample.

[0135] 60° gloss

[0136] 60° gloss (60GU) was measured using a Micro-TRI-gloss gloss meter (BYK-Gardner USA, Columbia, MD). This instrument was calibrated before each use.

[0137] particle size

[0138] The particle size of the filler particles in the slurry was measured by laser diffraction using a particle size analyzer (Mastersizer 3000, Malvern Instruments, Inc., Westborough, MA). DMAc was used as the carrier fluid.

[0139] Surface roughness

[0140] The surface roughness is 167 x 167 μm area (0.28 mm 2 It was measured using a ZeGage™ Pro 3D Optical Profiler (Zygo Corp., Middlefield, CT) across ). Maximum roughness (S pv , S z or R z ) is the maximum peak height of the surface being measured (S p ) and maximum valley depth (S v As the sum of ), S pv = S p + S v am.

[0141] Low-conductivity carbon black

[0142] A carbon black solution was prepared consisting of 90 wt% DMAc and 10 wt% carbon black powder (Special Black 4, SB4, Orion Engineered Carbons LLC, Kingwood, TX). The components were thoroughly mixed using a portable high-shear mixer.

[0143] Comparative Example 1 and Example 1

[0144] In the case of Comparative Example 1 and Example 1 (CE1 and E1), a soluble thermoplastic polyimide (Matrimid® 9725, Huntsman Corp., The Woodlands, TX) having a monomer composition of 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride / / 3-(4-aminophenyl)-1,1,3-trimethyl-5-indaneamine (BTDA 1.0 / / PIDA 1.0) was used as a dry powder.

[0145] For CE1, 5 g of dried polymer resin was added to 17.4 g of dimethylacetamide (DMAc, HPLC grade) and mixed in a centrifugal-air-rotating mixer (THINKY USA, Laguna Hills, CA) to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using the centrifugal-air-rotating mixer at 2000 rpm for 10 minutes. 2.5 g of a 10 wt% solution of SB4 carbon (Orion Engineered Carbons) in DMAc was added to the polyimide solution along with a release agent to facilitate easy removal of the film from the casting substrate. The solution was mixed using the centrifugal-air-rotating mixer at 2200 rpm for 2 minutes, followed by degassing at 2000 rpm for 5 minutes.

[0146] A solution was cast onto a matte PET substrate (Kaisei Industries, Inc., Japan) at 25°C to produce a cured film of 1–2 mil. After heating the film on the matte PET substrate to 80°C for 15 minutes, the matte PET surface was lifted and mounted onto an 8 x 12 inch frame. The mounted film was placed in a furnace. The furnace was heated from 120°C to 250°C (16°C / min) and maintained at 250°C for 20 minutes. After heating at 250°C for 20 minutes, the film was removed from the oven while "hot" and cooled in the air.

[0147] For E1, a polyimide solution containing carbon black was prepared as described above for CE1. Before the final degassing step, 1.04 g of a 10 wt% solution of Jeffamine® D-230 (Huntsman) in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0148] A solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil. After heating the film on the matte PET substrate to 80°C for 10 minutes, the matte PET surface was lifted and mounted on an 8 x 12 inch frame. The mounted film was placed in a furnace as described above for CE1 and heated.

[0149] Comparative Example 2 and Example 2

[0150] For the polyamic acid (PAA) solutions of Comparative Example 2 and Example 2 (CE2 and E2) having a monomer composition of BPADA 1.0 / / PIDA 1.0, 6.77 g of 3-(4-aminophenyl)-1,1,3-trimethyl-5-indaneamine (PIDA, Changzhou Sunlight Pharmaceutical Co., Ltd., China) was added to a 300 ml beaker in a nitrogen-purged glove box along with 180 g of DMAc. 13.20 g of 4,4'-Bisphenol A dianhydride (BPADA, Sabic, Riyadh, Saudi Arabia) was added in three fractions at 5–10 minute intervals. During these additions, the reaction mixture was maintained at 40°C. The reaction product had a weight-average molecular weight, M, with a dispersion of 1.85. w = 284,000 g / mol was maintained at 40℃ overnight.

[0151] For CE2 and E2, to prepare a substantially imidized polyimide solution (polyimide amic acid solution), 9.47 g of beta-picoline (Sigma Aldrich, Milwaukee, WI) and 10.38 g of acetic anhydride (Sigma Aldrich) were combined with the PAA solution. The reaction mixture was stirred at 40°C for 30 minutes, and then heated at 80°C for 3 hours to imidize the solution. 200 g of the room-temperature polymer solution was poured into 600 ml of methanol (Sigma Aldrich) in a blender and rapidly stirred to grind the polymer solid. The ground polymer solid was stirred in the blender for 10 minutes and then recovered by filtration. The polymer was air-dried overnight and then further dried overnight under vacuum at 35°C.

[0152] In the case of CE2, a polyimide solution containing carbon black was prepared as described above for CE1, cast, and heated to form a film.

[0153] For E2, a polyimide solution containing carbon black was prepared as described above for CE1. Before the final degassing step, 0.77 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0154] A solution was cast onto a matte PET substrate at 25°C to produce a cured film of approximately 2.5 mil. After heating the film on the matte PET substrate to 80°C for 15 minutes, the matte PET surface was lifted and mounted on an 8 x 12 inch frame. The mounted film was placed in a furnace as described above for CE1 and heated.

[0155] Table 1 summarizes the characteristics of E1-E2 and CE1-CE2. Both E1-E2 and CE1-CE2 exhibit excellent color and gloss characteristics, but as can be seen from the gel fraction measurements, the cross-linked films (E1 and E2) have superior chemical resistance. Additionally, the 60GU of the cross-linked films is lower than that of the non-cross-linked films.

[0156]

[0158] Comparative Example 3

[0159] In the case of Comparative Example 3 (CE3), the same Matrimid® 9725 polymer used in CE1 and E1 was used as a dry powder.

[0160] For CE3, 2.5 g of dried polymer resin was added to 8.7 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes, and then degassed at 2000 rpm for 10 minutes. 1.04 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0161] A solution was cast onto a Mylar® polyester film (DuPont Teijin Films USA, Chester, VA) substrate at 25°C to produce a cured film of 1–2 mil. After heating the film on the substrate to 80°C for 15 minutes, the surface of the polyester film was lifted and mounted on an 8 x 12 inch frame. The mounted film was placed in a furnace and heated as described above for CE1. The flat surface of the Mylar® polyester film (low S pv When polyimide is cast in ), a polymer film with high gloss is produced despite the high degree of crosslinking (see Table 1).

[0162] Example 3

[0163] For the polyamic acid (PAA) solution of Example 3 (E3) having a monomer composition of CBDA 0.6 / 6FDA 0.4 / TFMB 1.0, 2.268 kg of trifluoromethyl-benzidine (TFMB, Seika Corp., Wakayama Seika Kogyo Co., LTD., Japan) was added to a 72 L nitrogen-purged resin kettle along with 32.191 kg of DMAc. 1.252 kg of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, Daikin America Incorporated, Decatur, AL) and 0.829 kg of cyclobutane dianhydride (CBDA, Wilshire Technologies, Princeton, NJ) were added in three fractions at 60-minute intervals. During these additions, the reaction mixture was maintained at 40°C. A small amount of 6FDA powder was added to polymerize the polymer to 12 poise (completed).

[0164] For E3, to prepare a substantially imidized polyimide solution (polyimide amic acid solution), 2.787 kg of DMAc was additionally added and stirred for 60 minutes. 1.65 kg of beta-picoline and 1.808 kg of acetic anhydride were combined with the PAA solution. The reaction mixture was heated at 80°C for 2 hours to imidize the solution. 1,000 g of the room-temperature polymer solution was poured into 2 L of methanol in a blender and rapidly stirred to grind the polymer solid. The ground polymer solid was stirred in the blender for 10 minutes and then recovered by filtration. The polymer was air-dried overnight and then further dried overnight under vacuum at 50°C.

[0165] For E3, 2.5 g of dried polymer was added to 21.2 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes. 0.5 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0166] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0167] Example 4

[0168] For the polyamic acid (PAA) solution of Example 4 (E4) having a monomer composition of BPADA 1.0 / / 3,4-ODA 1.0, 5.56 g of 3,4-oxydiphenylamine (3,4-ODA, Seika Corp., Wakayama Seika Kogyo Co., LTD., Japan) was added to a 300 ml beaker in a nitrogen-purged glove box along with 180 g of DMAc. 14.415 g of BPADA was added in three fractions at 5–10 minute intervals. During these additions, the reaction mixture was maintained at 40°C. The reaction product was prepared with a weight-average molecular weight, M, having a dispersion of 2.00. w = 184,000 g / mol was maintained at 40℃ overnight.

[0169] For E4, to prepare a substantially imidized polyimide solution (polyimide amic acid solution), 10.34 g of beta-picoline and 11.33 g of acetic anhydride were combined with the PAA solution. The reaction mixture was stirred at 40°C for 30 minutes, and then heated at 80°C for 3 hours to imidize the solution. 200 g of the room-temperature polymer solution was poured into 600 ml of methanol in a blender and rapidly stirred to grind the polymer solid. The ground polymer solid was stirred in the blender for 10 minutes and then recovered by filtration. The polymer was air-dried overnight and then further dried overnight under vacuum at 35°C.

[0170] For E4, 2.5 g of dried polymer was added to 8.7 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes. 0.42 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0171] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0172] Example 5

[0173] For the polyamic acid (PAA) solution of Example 5 (E5) having a monomer composition of BPADA 1.0 / / RODA 1.0, 8.647 g of 1,3-bis(4-aminophenoxy)benzene (RODA) was added to a 300 ml beaker in a nitrogen-purged glove box along with 180 g of DMAc. 8.630 g of BPADA was added in a smaller aliquot and stirred until completely dissolved. During this addition, the reaction mixture was maintained at 40°C. The reaction product was prepared with a weight-average molecular weight, M, having a dispersion of 2.00. w = 184,000 g / mol was maintained at 40℃ overnight.

[0174] For E5, to prepare a substantially imidized polyimide solution (polyimide amic acid solution), 17.0 g of DMAc was additionally added to the PAA solution along with 10.31 g of beta-picoline and 11.31 g of acetic anhydride. The reaction mixture was stirred at room temperature for about 2 hours. During this time, the viscosity of the solution increased slightly, and 50 ml of DMAc was additionally added. The solution was left to be stirred overnight.

[0175] 200 g of polymer solution was mixed with approximately 600 ml of methanol and mixed in a laboratory blender until fine powder solid particles were produced. Subsequently, the resulting suspension was filtered, air-dried overnight at room temperature, and vacuum-dried overnight at 50°C.

[0176] For E5, 2.5 g of dried polymer was added to 12.9 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes. 0.42 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0177] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0178] Example 6

[0179] In the case of Example 6 (E6), the same Matrimid® 9725 polymer used in CE1 and E1 was used as a dry powder.

[0180] For E6, 2.5 g of dried polymer resin was added to 8.7 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes, followed by degassing at 2000 rpm for 10 minutes. 2.08 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0181] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0182] Example 7

[0183] In the case of Example 7 (E7), the same Matrimid® 9725 polymer used in CE1 and E1 was used as a dry powder.

[0184] For E7, 2.5 g of dried polymer resin was added to 8.7 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes, and then degassed at 2000 rpm for 10 minutes. 0.66 g of a 10 wt% solution of Jeffamine® T-403 (Huntsman) in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0185] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0186] Example 8

[0187] In the case of Example 8 (E8), the same Matrimid® 9725 polymer used in CE1 and E1 was used as a dry powder.

[0188] For E8, 2.5 g of dried polymer resin was added to 8.7 g of DMAc and mixed in a centrifugal-co-rotating mixer. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 1.25 g of a 10 wt% solution of SB4 carbon in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes, and then degassed at 2000 rpm for 10 minutes. 0.31 g of a 10 wt% solution of m-xylylenediamine (MXD, Sigma Aldrich, Milwaukee, WI) in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0189] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0190] Example 9

[0191] In the case of Example 9 (E9), the same Matrimid® 9725 polymer used in CE1 and E1 was used as a dry powder.

[0192] For E9, 2.5 g of dried polymer resin was added to 4.95 g of DMAc and mixed in a centrifugal-co-rotating mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-co-rotating mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc and 5 g of a 10 wt% solution of perylene black (Paliogen® Black L 0086, BASF SE, Germany) in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-co-rotating mixer at 2200 rpm for 2 minutes, followed by degassing at 2000 rpm for 10 minutes. 1.04 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0193] As described above for CE1, a solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1 to 2 mil.

[0194] Example 10

[0195] In the case of Example 10 (E10), the same Matrimid® 9725 polymer used in CE1 and E1 was used as a dry powder.

[0196] For E10, 2.5 g of dried polymer resin was added to 7.45 g of DMAc and mixed in a centrifugal-coil mixer to obtain a solution. The solution was degassed by forcibly ejecting gas from the polymer using a centrifugal-coil mixer at 2000 rpm for 10 minutes. 0.05 g of a 2.5 wt% solution of triphenyl phosphite belt release agent in DMAc, 1.25 g of a 10 wt% solution of SB4 carbon in DMAc, and 1.25 g of a 10 wt% solution of silica matting agent (Syloid® C807, WR Grace & Co., Columbia, MD) in DMAc were added to the polyimide solution. The solution was mixed using a centrifugal-coil mixer at 2200 rpm for 2 minutes, and then degassed at 2000 rpm for 10 minutes. 1.04 g of a 10 wt% solution of Jeffamine® D-230 in DMAc was added to the polymer solution. The solution was mixed using a centrifugal-rotating mixer at 2200 rpm for 30 seconds while cooling in a cold cup, then degassed at 2000 rpm for 5 minutes and maintained at a low temperature.

[0197] As described above for CE1, a cured film of 1 to 2 mil was produced by casting the solution onto a matte PET substrate at 25°C. As summarized in Table 2, E3-E10 show various cross-linked polymers of low refractive index with low color and gloss for films having sufficient surface roughness.

[0198] Comparative Example 4

[0199] For the polyamic acid solution of Comparative Example 4 (CE4) having a monomer composition of BPDA 1.0 / / PPD 1.0, 10.95 g of p-phenylenediamine (PPD) was added to a nitrogen-purged 300 ml reaction vessel along with 160.17 g of anhydrous DMAc. 28.89 g of 3,3',4,4'-biphenyl tetracarboxylic acid dianhydride (BPDA) was added over several minutes. The reaction mixture was stirred until all monomers had reacted. The total stoichiometric ratio of dianhydride to diamine was approximately 0.97:1. The mixture achieved a polymer viscosity of 75–250 Poise in approximately 20% polyamic acid solid. A small amount of the PMDA solution in DMAc was added to polymerize ("complete") the polymer to provide the desired viscosity and increase the molecular weight. The polymer solution was stored in a freezer until use.

[0200] A solution was prepared by adding 8.42 g of a 10 wt% solution of SB4 carbon in DMAc to 91.58 g of a polymer solution and mixed in a centrifugal-rotating mixer. The solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1–2 mil. After heating the film on the matte PET substrate at 90°C for 20 minutes, the matte PET surface was lifted and mounted on an 8 x 12 inch frame. The mounted film was placed in a furnace. After heating the furnace from 120°C to 320°C (16°C / min), the film was removed from the oven while "hot," placed at 400°C for 5 minutes, and then removed and cooled in the air.

[0201] Comparative Example 5

[0202] For the polyamic acid solution of Comparative Example 5 (CE5) having a monomer composition of 0.5 ODPA / 0.5 PMDA / 0.5 MPD / 0.5 BAPP, 20.48 g of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) and 5.40 g of m-phenylenediamine (MPD) were added to a nitrogen-purged 300 ml reaction vessel along with 148.2 g of DMAc. 10.45 g of pyromellitic dianhydride (PMDA) and 15.48 g of 4,4'-oxydiphthalic anhydride (ODPA) were added over several minutes. The reaction mixture was stirred until all monomers reacted. The total stoichiometric ratio of dianhydrides to diamines was approximately 0.98:1. The mixture achieved a polymer viscosity of 75–250 Poise in approximately 26% polyamic acid solid. A small amount of PMDA solution in DMAc was added to polymerize ("completed") the polymer to provide the desired viscosity and increase the molecular weight. The polymer solution was stored in a freezer until use.

[0203] A solution was prepared by adding 11.84 g of a 10 wt% solution of SB4 carbon in DMAc to 88.64 g of a polymer solution and mixed in a centrifugal-rotating mixer. The solution was cast onto a matte PET substrate at 25°C to produce a cured film of 1–2 mil. After heating the film on the matte PET substrate at 90°C for 20 minutes, the matte PET surface was lifted and mounted on an 8 x 12 inch frame. The mounted film was placed in a furnace. After heating the furnace from 120°C to 350°C (16°C / min), the film was removed from the oven while "hot" and cooled in the air. As summarized in Table 2, CE4 and CE5 show that it is difficult to achieve both low chromaticity and low gloss in a single-layer polymer film when the refractive index is too high (CE4) or the surface roughness is too low (CE5).

[0204]

[0206] It should be noted that not all actions described above are required in the general description, that parts of specific actions may not be necessary, and that additional actions beyond those described may be performed. Furthermore, the order in which the actions are listed is not necessarily the order in which they are performed. After reading this specification, a person skilled in the art will be able to determine which actions may be used for specific needs or requirements.

[0207] In the foregoing specification, the present invention has been described with reference to specific embodiments. However, those skilled in the art understand that various modifications and changes may be made without departing from the scope of the invention as set forth in the following claims. All features disclosed herein may be replaced by alternative features that provide the same, equivalent, or similar purposes.

[0208] Accordingly, this specification should be regarded as illustrative rather than restrictive, and all such variations are included within the scope of the invention.

[0209] Advantages, other advantages, and solutions to problems have been set forth in relation to specific embodiments. However, such advantages, advantages, solutions to problems, and any element(s) that may give rise to or make more apparent any advantage, advantage, or solution to problems shall not be interpreted as important, essential, or fundamental features or elements of any or all claims.

Claims

Claim 1 A single-layer polymer film comprising 60 to 99 wt% of cross-linked polyimide having a gel fraction in the range of 20 to 100% and a refractive index of 1.74 or less; and 1 to 40 wt% of a coloring agent, wherein the maximum roughness (S pv A single-layer polymer film having a textured surface with a thickness of 6 μm or more, an L* color intensity of 30 or less, and a 60° gloss intensity of 15 or less. Claim 2 A single-layer polymer film according to claim 1, further comprising a matting agent. Claim 3 Coverlay for a printed circuit board comprising the single-layer polymer film of claim 1. Claim 4 A method for forming a single-layer polymer film comprising a cross-linked polyimide film comprising a dianhydride and a diamine, wherein the dianhydride, the diamine, or both the dianhydride and the diamine comprise a cycloaliphatic monomer, an aliphatic monomer, or both a cycloaliphatic monomer and an aliphatic monomer, and the polymer film has an L* color value of 30 or less and a 60° gloss value of 15 or less, and the cross-linked polyimide film comprises: (a) a step of polymerizing the dianhydride and the diamine in the presence of a solvent to obtain a polyamic acid solution; (b) a step of imidizing the polyamic acid solution to form a substantially imidized solution; (c) a step of adding a cross-linking agent and a coloring agent to the substantially imidized solution; and (d) the substantially imidized solution to a maximum roughness (S pv A method formed by the steps of: (e) forming a film by casting it onto a removable substrate having a textured surface having a thickness of 6 μm or more; (f) crosslinking the polyimide while drying the film; and (f) removing the single-layer polymer film from the textured substrate. Claim 5 A method for forming a single-layer polymer film comprising a cross-linked polyimide film comprising a dianhydride and a diamine, wherein the dianhydride, the diamine, or both the dianhydride and the diamine comprise a cycloaliphatic monomer, an aliphatic monomer, or both a cycloaliphatic monomer and an aliphatic monomer, and the polymer film has an L* color value of 30 or less and a 60° gloss value of 15 or less, and the cross-linked polyimide film comprises: (a) polymerizing the dianhydride and the diamine in the presence of a first solvent to obtain a polyamic acid solution; (b) imidizing the polyamic acid solution to form a substantially imidized first solution; (c) precipitating the substantially imidized first solution using an antisolvent; (d) filtering and drying the substantially imidized first solution to obtain a solid polyimide resin; (e) dissolving the solid polyimide resin in a second solvent and a cross-linking agent and low-conductivity carbon black Step of forming a second solution substantially imidized by adding the substantially imidized second solution; (f) the second solution substantially imidized to a maximum roughness (S pv A method formed by the steps of: (g) forming a film by casting it onto a removable substrate having a textured surface having a thickness of 6 μm or more; (h) crosslinking the polyimide while drying the film; and (h) removing the single-layer polymer film from the textured substrate. Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete

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