Disclosure of Invention
The invention aims to provide a polyimide composite resin with a low dielectric constant, a preparation method and application thereof, aiming at the defects of the prior art. By introducing a polyimide unit into the polyimide resin, the average dipole moment of a molecular chain is reduced, and the dielectric constant of the resin is reduced; by introducing the branched chain structure, not only molecular chain gaps are increased, the dielectric constant is further reduced, but also the molecular chain arrangement conditions of the polymethine unit in two different directions, namely the transverse direction and the longitudinal direction, can be improved, and certain mechanical properties in all directions are ensured. The introduction of the fluorine-containing group not only brings the effect of reducing the dielectric constant, but also increases the flexibility of the polyimide molecular chain; the flexible polyimide molecular chain unit and the high-rigidity polyimide molecular chain unit are mutually linked, so that the flexibility/rigidity of the molecular chain is in a proper range, and the processing performance, the mechanical performance and the linear thermal expansion coefficient performance are considered. Such a polyimide composite resin having a low dielectric constant property is widely used in the field of electronic information.
The purpose of the invention is realized by the following technical scheme: a polyimide composite resin with low dielectric constant is characterized in that the composite resin is composed of polyimide resin units and polyimide resin units which are linked in a copolymerization mode; the copolymer forms a network structure, the composite resin has a general formula of the following structure, and the units are mixed and copolymerized uniformly:
wherein Ar1 is a monomer represented by the following formula (I) and is selected from the group consisting of a residue of pyromellitic dianhydride, a residue of 3,3',4,4' -biphenyltetracarboxylic dianhydride, a residue of 4,4'- (hexafluoroisopropyl) bisphthalic dianhydride, a residue of 1, 4-difluoropyromellitic dianhydride, a residue of 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, a residue of 2,3,3',4 '-biphenyltetracarboxylic dianhydride, a residue of 3,3',4,4 '-diphenylethertetracarboxylic dianhydride, a residue of 3,3',4,4 '-benzophenonetetracarboxylic dianhydride, a residue of 4,4' -terephthalobiphthalic anhydride, a residue of bisphenol A type diether dianhydride, a residue of 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, and a residue of 2,3,6, one or more of residues of 7-tetracarboxyl-9, 9-bis (trifluoromethyl) xanthene dianhydride, residues of 1, 4-bis (trifluoromethyl) -2,3,5, 6-benzene tetracarboxylic dianhydride and residues of 1, 4-bis (3, 4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride are mixed according to any proportion;
ar2 is prepared by mixing one or more of residues of terephthalaldehyde, residues of o-phthalaldehyde, residues of m-phthalaldehyde, residues of 4, 4-biphenyldicarboxaldehyde, residues of 2, 3-naphthaldehyde and residues of 2,3,5, 6-tetrafluoroterephthalaldehyde according to any proportion;
b1 is composed of a residue of p-phenylenediamine, a residue of m-phenylenediamine, a residue of biphenyldiamine, a residue of 4,4' -diamino-2, 2' -dimethylbiphenyl, a residue of 4,4' -diamino-3, 3' -dimethylbiphenyl, a residue of 2,2' -bis (trifluoromethyl) diaminobiphenyl, a residue of 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, a residue of 2, 2-bis [4- (2-trifluoromethyl-4-aminophenoxy) phenyl ] propane, a residue of 2, 2-bis (4-aminophenyl) hexafluoropropane, a residue of 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, a residue of 2, 2-bis [4- (3-aminophenoxy) phenyl ] hexafluoropropane, a residue of 4, 2-bis [4- (3-aminophenoxy) phenyl ], A residue of 4,4' -diaminodiphenyl ether, a residue of 3,4' -diaminodiphenyl ether, a residue of 4,4' -diaminobenzophenone, a residue of 4,4' -diaminodiphenylmethane, a residue of 4,4' -diaminophenylsulfone, a residue of bis (3-amino-4-hydroxyphenyl) sulfone, one or more of a residue of 1, 3-bis (3-aminophenoxy) benzene, a residue of 1, 3-bis (4-aminophenoxy) benzene, a residue of 4,4 '-bis (4-aminophenoxy) biphenyl, a residue of 4,4' -bis (3-aminophenoxy) biphenyl, a residue of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane and a residue of bis [4- (3-aminophenoxy) phenyl ] sulfone are mixed according to any proportion;
b2 is formed by mixing one or more of residues of 1,3, 5-triaminobenzene, residues of tri (2-aminoethyl) amine, residues of tri (4-aminophenyl) amine and residues of 1,3, 5-tri (4-aminophenyl) benzene according to any proportion;
m1, m2 and n1 are natural numbers, n2 is an even number, 0.5-m 1/(m1+ m2) <1, 0.8-n 1/(n1+ n2) <1, 20-m 1+ m2+ n1+ n2) < 400, and n1+ 1.5-n 2 ═ m1+ m 2.
Further, Ar1 in the formula comprises one or two of residues of pyromellitic dianhydride, 3',4,4' -biphenyltetracarboxylic dianhydride, 4,4' - (hexafluoroisopropyl) bisphthalic dianhydride, 1, 4-difluoropyromellitic dianhydride and 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, and the total amount of the residues accounts for 50-100% of the total molar amount of Ar 1;
ar2 in the general formula comprises residues of 4, 4-biphenyldicarboxaldehyde and residues of 2,3,5, 6-tetrafluoroterephthalaldehyde, and the total amount of the residues accounts for 50-100% of the total mole amount of Ar 2;
b1 in the formula comprises any one or two of residues of p-phenylenediamine, 4 '-diamino-2, 2' -dimethyl biphenyl, 2 '-bis (trifluoromethyl) diamino biphenyl, 2' -bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2-bis (4-aminophenyl) hexafluoropropane and 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, and the total amount of the residues accounts for 50-100% of the total molar amount of B1;
b2 in the formula comprises residues of 1,3, 5-tris (4-aminophenyl) benzene and is present in a total amount of 50-100% based on the total molar amount of B2.
Further, Ar1 in the general formula comprises one or two of residues of 1, 4-difluoropyromellitic dianhydride and residues of 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, and the total amount of the residues accounts for 80-100% of the total mole amount of Ar 1;
b1 in the formula comprises any one or two of residues of 4,4' -diamino-2, 2' -dimethyl biphenyl, residues of 2,2' -bis (trifluoromethyl) diamino biphenyl and residues of 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, and the total amount of the residues accounts for 80-100% of the total molar amount of B1;
a preparation method of polyimide composite resin with low dielectric constant comprises the following steps:
(1) preparing a precursor solution of the polyimide composite resin: under the nitrogen atmosphere, dissolving a mol of diamine compound and b mol of triamine compound in a strong polar solvent while stirring in a container to obtain a solution, wherein the sum of the mass percentages of the diamine compound and the triamine compound in the solution is 5-13%; then d mol of dimethyl aldehyde compound is added, the temperature of the solution is controlled to be 0-50 ℃ under the nitrogen atmosphere, and the reaction is carried out for 4-24 h; then c moles of the tetracarboxylic dianhydride compound are added into the solution for three times, and the addition amount of each time respectively accounts for 60%, 30% and 10% of the total weight of the tetracarboxylic dianhydride compound; continuously reacting for 4-48h in nitrogen atmosphere, controlling the solution temperature at 0-50 ℃, and obtaining a precursor solution of the polyimide composite resin after reaction; wherein c/(c + d) is more than or equal to 0.5 and less than 1, a/(a + b) is more than or equal to 0.8 and less than 1, and (a + b + c + d) is more than or equal to 20 and less than or equal to 400, wherein (c + d) is (a + 1.5) b which is (0.95-1.05) to 1;
wherein the tetracarboxylic dianhydride compound is selected from pyromellitic dianhydride, 3,3',4,4' -biphenyltetracarboxylic dianhydride, 4,4'- (hexafluoroisopropyl) bisphthalic dianhydride, 1, 4-difluoropyromellitic dianhydride, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, 2,3,3',4 '-biphenyltetracarboxylic dianhydride, 3,3',4,4 '-diphenyl ether dianhydride, 3,3',4,4 '-benzophenone tetracarboxylic dianhydride, 4,4' -terephthaloylbisphthalic anhydride, bisphenol A type diether dianhydride, 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, 2,3,6, 7-tetracarboxyl-9, 9-bis (trifluoromethyl) xanthene dianhydride, One or more of 1, 4-bis (trifluoromethyl) -2,3,5, 6-benzene tetracarboxylic dianhydride and 1, 4-bis (3, 4-dicarboxy trifluoro phenoxy) tetrafluorobenzene dianhydride are mixed according to any proportion;
the diformaldehyde compound is formed by mixing one or more of terephthalaldehyde, o-phthalaldehyde, m-phthalaldehyde, 4-phthalaldehyde, 2, 3-naphthaldehyde and 2,3,5, 6-tetrafluoro-terephthalaldehyde according to any proportion;
diamine compounds selected from the group consisting of p-phenylenediamine, m-phenylenediamine, biphenyldiamine, 4' -diamino-2, 2' -dimethylbiphenyl, 4' -diamino-3, 3' -dimethylbiphenyl, 2' -bis (trifluoromethyl) diaminobiphenyl, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2-bis [4- (2-trifluoromethyl-4-aminophenoxy) phenyl ] propane, 2-bis (4-aminophenyl) hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2-bis [4- (3-aminophenoxy) phenyl ] hexafluoropropane, 4' -diaminodiphenyl ether, 4' -diaminodiphenyl ether, and mixtures thereof, One or more of 3,4 '-diaminodiphenyl ether, 4' -diaminobenzophenone, 4 '-diaminodiphenylmethane, 4' -diaminophenylsulfone, bis (3-amino-4-hydroxyphenyl) sulfone, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4 '-bis (4-aminophenoxy) biphenyl, 4' -bis (3-aminophenoxy) biphenyl, 2-bis [4- (4-aminophenoxy) phenyl ] propane and bis [4- (3-aminophenoxy) phenyl ] sulfone are mixed according to any proportion to form the composition;
the triamine compound is formed by mixing one or more of 1,3, 5-triaminobenzene, tri (2-aminoethyl) amine, tri (4-aminophenyl) amine and 1,3, 5-tri (4-aminophenyl) benzene according to any proportion;
the strong polar solvent is formed by mixing one or more of N, N-dimethylacetamide (DMAc), N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP) and m-cresol according to any proportion;
(2) coating the precursor solution of the polyimide composite resin prepared in the step (1) on a carrier, wherein the film thickness of the dried polyimide composite resin is 10-30 mu m; then volatilizing at 80-150 ℃ to ensure that the content of the strong polar solvent is between 15-25wt percent, thus obtaining a precursor dry film layer of the polyimide composite resin;
(3) carrying out thermal curing on the carrier coated with the precursor dry film layer of the polyimide composite resin at the temperature of 280-350 ℃ in the nitrogen atmosphere; curing the precursor dry film layer of the polyimide composite resin to form an insulating film base layer;
(4) and (4) removing the insulating film base layer in the step (3) from the surface of the carrier by a water boiling method to obtain the polyimide composite resin with low dielectric constant.
Further, the tetracarboxylic dianhydride group compound comprises one or two of pyromellitic dianhydride, 3',4,4' -biphenyltetracarboxylic dianhydride, 4,4' - (hexafluoroisopropyl) bisphthalic dianhydride, 1, 4-difluoropyromellitic dianhydride and 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, and the total amount of the compounds accounts for 50-100% of the total molar amount of the tetracarboxylic dianhydride group compound; the diformaldehyde compound comprises one or two of 4, 4-biphenyldicarboxaldehyde and 2,3,5, 6-tetrafluoroterephthalaldehyde, and the total amount of the diformaldehyde compound accounts for 50-100% of the total molar amount of the diformaldehyde compound; the diamine compound comprises any one or two of p-phenylenediamine, 4 '-diamino-2, 2' -dimethyl biphenyl, 2 '-bis (trifluoromethyl) diamino biphenyl, 2' -bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2-bis (4-aminophenyl) hexafluoropropane and 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, and the total amount of the diamine compound accounts for 50-100% of the total mole amount of the diamine compound; the triamine compound comprises 1,3, 5-tri (4-aminophenyl) benzene, and the total amount of the triamine compound accounts for 50-100% of the total mol amount of the triamine compound.
Further, the tetracarboxylic dianhydride compound comprises one or two of 1, 4-difluoro pyromellitic dianhydride and 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, and the total amount of the tetracarboxylic dianhydride compound accounts for 80-100% of the total mole amount of the tetracarboxylic dianhydride compound; the diamine compound comprises 4,4' -diamino-2, 2' -dimethyl biphenyl, 2' -bis (trifluoromethyl) diamino biphenyl and 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, and the total amount of the diamine compound accounts for 80-100% of the total mole amount of the tetracarboxylic dianhydride compound.
The application of the polyimide composite resin with the low dielectric constant is characterized in that the polyimide composite resin with the low dielectric constant is applied to prepare a single-sided flexible copper clad laminate, the single-sided flexible copper clad laminate comprises a copper foil layer and a polyimide layer positioned on the copper foil layer, and the polyimide layer can be composed of a layer of polyimide composite resin with the low dielectric constant or a multilayer structure formed by multiple polyimide composite resins with the low dielectric constants; the thickness of the copper foil layer is not more than 105 mu m, and the thickness of the polyimide composite resin layer is 5-35 mu m.
The application of the polyimide composite resin with the low dielectric constant is characterized in that the polyimide composite resin with the low dielectric constant is applied to prepare a double-sided flexible copper clad laminate, the double-sided flexible copper clad laminate comprises two copper foil layers and a polyimide layer positioned between the two copper foil layers, and the polyimide layer can be composed of a layer of polyimide composite resin with the low dielectric constant or a multilayer structure formed by multiple polyimide composite resins with low dielectric constants; the thickness of the copper foil layer is not more than 105 mu m, and the thickness of the polyimide composite resin layer is 10-70 mu m.
A positive photosensitive covering film is prepared by mixing precursor solution of polyimide composite resin with diazonaphthoquinone photosensitizer; the weight percentage of the diazonaphthoquinone sensitizer in the positive photosensitive covering film is 10-40%; the film thickness of the positive photosensitive covering film is 5-50 um; the precursor structural formula of the polyimide composite resin is shown as the following general formula:
wherein Ar1 is a monomer represented by the following formula (I) and is selected from the group consisting of a residue of pyromellitic dianhydride, a residue of 3,3',4,4' -biphenyltetracarboxylic dianhydride, a residue of 4,4'- (hexafluoroisopropyl) bisphthalic dianhydride, a residue of 1, 4-difluoropyromellitic dianhydride, a residue of 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, a residue of 2,3,3',4 '-biphenyltetracarboxylic dianhydride, a residue of 3,3',4,4 '-diphenylethertetracarboxylic dianhydride, a residue of 3,3',4,4 '-benzophenonetetracarboxylic dianhydride, a residue of 4,4' -terephthalobiphthalic anhydride, a residue of bisphenol A type diether dianhydride, a residue of 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, and a residue of 2,3,6, one or more of residues of 7-tetracarboxyl-9, 9-bis (trifluoromethyl) xanthene dianhydride, residues of 1, 4-bis (trifluoromethyl) -2,3,5, 6-benzene tetracarboxylic dianhydride and residues of 1, 4-bis (3, 4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride are mixed according to any proportion;
ar2 is prepared by mixing one or more of residues of terephthalaldehyde, residues of o-phthalaldehyde, residues of m-phthalaldehyde, residues of 4, 4-biphenyldicarboxaldehyde, residues of 2, 3-naphthaldehyde and residues of 2,3,5, 6-tetrafluoroterephthalaldehyde according to any proportion;
b1 is composed of a residue of p-phenylenediamine, a residue of m-phenylenediamine, a residue of biphenyldiamine, a residue of 4,4' -diamino-2, 2' -dimethylbiphenyl, a residue of 4,4' -diamino-3, 3' -dimethylbiphenyl, a residue of 2,2' -bis (trifluoromethyl) diaminobiphenyl, a residue of 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, a residue of 2, 2-bis [4- (2-trifluoromethyl-4-aminophenoxy) phenyl ] propane, a residue of 2, 2-bis (4-aminophenyl) hexafluoropropane, a residue of 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, a residue of 2, 2-bis [4- (3-aminophenoxy) phenyl ] hexafluoropropane, a residue of 4, 2-bis [4- (3-aminophenoxy) phenyl ], A residue of 4,4' -diaminodiphenyl ether, a residue of 3,4' -diaminodiphenyl ether, a residue of 4,4' -diaminobenzophenone, a residue of 4,4' -diaminodiphenylmethane, a residue of 4,4' -diaminophenylsulfone, a residue of bis (3-amino-4-hydroxyphenyl) sulfone, one or more of a residue of 1, 3-bis (3-aminophenoxy) benzene, a residue of 1, 3-bis (4-aminophenoxy) benzene, a residue of 4,4 '-bis (4-aminophenoxy) biphenyl, a residue of 4,4' -bis (3-aminophenoxy) biphenyl, a residue of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane and a residue of bis [4- (3-aminophenoxy) phenyl ] sulfone are mixed according to any proportion;
b2 is formed by mixing one or more of residues of 1,3, 5-triaminobenzene, residues of tri (2-aminoethyl) amine, residues of tri (4-aminophenyl) amine and residues of 1,3, 5-tri (4-aminophenyl) benzene according to any proportion;
m1, m2 and n1 are natural numbers, n2 is an even number, 0.5-m 1/(m1+ m2) <1, 0.8-n 1/(n1+ n2) <1, 20-m 1+ m2+ n1+ n2) < 400, and n1+ 1.5-n 2 ═ m1+ m 2.
The method for preparing the positive photosensitive cover film comprises the following steps:
(1) preparing a precursor solution of the polyimide composite resin: under the nitrogen atmosphere, dissolving a mol of diamine compound and b mol of triamine compound in a strong polar solvent while stirring in a container to obtain a solution, wherein the sum of the mass percentages of the diamine compound and the triamine compound in the solution is 5-13%; then d mol of dimethyl aldehyde compound is added, the temperature of the solution is controlled to be 0-50 ℃ under the nitrogen atmosphere, and the reaction is carried out for 4-24 h; then c moles of the tetracarboxylic dianhydride compound are added into the solution for three times, and the addition amount of each time respectively accounts for 60%, 30% and 10% of the total weight of the tetracarboxylic dianhydride compound; continuously reacting for 4-48h in nitrogen atmosphere, controlling the solution temperature at 0-50 ℃, and obtaining a precursor solution of the polyimide composite resin after reaction; wherein c/(c + d) is more than or equal to 0.5 and less than 1, a/(a + b) is more than or equal to 0.8 and less than 1, and (a + b + c + d) is more than or equal to 20 and less than or equal to 400, wherein (c + d) is (a + 1.5) b which is (0.95-1.05) to 1;
wherein the tetracarboxylic dianhydride compound is selected from pyromellitic dianhydride, 3,3',4,4' -biphenyltetracarboxylic dianhydride, 4,4'- (hexafluoroisopropyl) bisphthalic dianhydride, 1, 4-difluoropyromellitic dianhydride, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride, 2,3,3',4 '-biphenyltetracarboxylic dianhydride, 3,3',4,4 '-diphenyl ether dianhydride, 3,3',4,4 '-benzophenone tetracarboxylic dianhydride, 4,4' -terephthaloylbisphthalic anhydride, bisphenol A type diether dianhydride, 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, 2,3,6, 7-tetracarboxyl-9, 9-bis (trifluoromethyl) xanthene dianhydride, One or more of 1, 4-bis (trifluoromethyl) -2,3,5, 6-benzene tetracarboxylic dianhydride and 1, 4-bis (3, 4-dicarboxy trifluoro phenoxy) tetrafluorobenzene dianhydride are mixed according to any proportion;
the diformaldehyde compound is formed by mixing one or more of terephthalaldehyde, o-phthalaldehyde, m-phthalaldehyde, 4-phthalaldehyde, 2, 3-naphthaldehyde and 2,3,5, 6-tetrafluoro-terephthalaldehyde according to any proportion;
diamine compounds selected from the group consisting of p-phenylenediamine, m-phenylenediamine, biphenyldiamine, 4' -diamino-2, 2' -dimethylbiphenyl, 4' -diamino-3, 3' -dimethylbiphenyl, 2' -bis (trifluoromethyl) diaminobiphenyl, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 2-bis [4- (2-trifluoromethyl-4-aminophenoxy) phenyl ] propane, 2-bis (4-aminophenyl) hexafluoropropane, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2-bis [4- (3-aminophenoxy) phenyl ] hexafluoropropane, 4' -diaminodiphenyl ether, 4' -diaminodiphenyl ether, and mixtures thereof, One or more of 3,4 '-diaminodiphenyl ether, 4' -diaminobenzophenone, 4 '-diaminodiphenylmethane, 4' -diaminophenylsulfone, bis (3-amino-4-hydroxyphenyl) sulfone, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4 '-bis (4-aminophenoxy) biphenyl, 4' -bis (3-aminophenoxy) biphenyl, 2-bis [4- (4-aminophenoxy) phenyl ] propane and bis [4- (3-aminophenoxy) phenyl ] sulfone are mixed according to any proportion to form the composition;
the triamine compound is formed by mixing one or more of 1,3, 5-triaminobenzene, tri (2-aminoethyl) amine, tri (4-aminophenyl) amine and 1,3, 5-tri (4-aminophenyl) benzene according to any proportion;
the strong polar solvent is formed by mixing one or more of N, N-dimethylacetamide (DMAc), N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP) and m-cresol according to any proportion;
(2) adding diazonaphthoquinone sensitizer into the precursor solution of the polyimide composite resin prepared in the step (1), so that the weight percentage of the diazonaphthoquinone sensitizer in the final positive photosensitive cover film is 10-40%; after adding, controlling the temperature of the solution to be 0-50 ℃ in the nitrogen atmosphere, and continuously stirring for 4-24h to obtain a photosensitive mixture solution;
(3) film preparation: coating the photosensitive mixture solution obtained in the step (2) on a carrier to ensure that the film thickness of the dried photosensitive mixture is 5-50 μm; and then volatilizing at 60-90 ℃ to ensure that the content of the strong polar solvent is between 2-15 wt% to obtain a photosensitive mixture film, namely the positive photosensitive covering film.
The invention has the following beneficial effects:
1. the polyimide resin unit of the invention adopts fluorine-containing monomers, thereby not only reducing the dielectric constant of the polyimide resin, but also improving the flexibility of the polyimide molecular chain.
2. The flexible molecular chain of the polyimide can improve the high rigidity of the molecular chain of the polyimide, so that the rigidity of the molecular chain of the polymer is in a reasonable range. On one hand, the directional arrangement capability of molecular chains is ensured, and the linear thermal expansion coefficient of the polyimide resin is reduced; on the other hand, the rigidity and flexibility of the poly-azomethine molecular chain are adjusted, and the mechanical property and the processing property are improved.
3. The polyimide resin unit is composed of an imine group, and has a lower dipole moment than a five-membered imide ring. The introduction of the polyimide unit reduces the dipole moment of a polyimide molecular chain and the dielectric constant of the polyimide resin.
4. Optimizing a molecular chain of the polyimide composite resin, and introducing a triamine monomer to obtain a branched molecular chain; mechanical properties in all directions are averaged after branching, and transverse fibrosis splitting caused by high rigidity of a polymethine unit is avoided; branching also increases inter-molecular chain voids, further reducing the dielectric constant to some extent.
5. The polyimide unit and the polyimide unit are copolymerized, so that the dielectric constant is reduced, the good mechanical property is ensured, and the linear thermal expansion coefficient can be regulated and controlled. The material has better application in the field of 5G circuit boards in flexible copper clad plate materials.
Detailed Description
The following representative examples are intended to illustrate the invention, but are not intended to limit the scope of the invention described herein.
The abbreviations used in the examples represent the following:
and (3) PMDA: pyromellitic dianhydride;
BPDA: 3,3',4,4' -biphenyltetracarboxylic dianhydride;
6 FDA: 4,4' - (hexafluoroisopropyl) diphthalic dianhydride;
PF2 DA: 1, 4-difluoropyromellitic dianhydride;
BFDA: 2, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] hexafluoropropane dianhydride;
TPAL: terephthalaldehyde;
BDAL: 4, 4-biphenyldicarboxaldehyde;
NDAL: 2, 3-naphthalene dicarboxaldehyde;
TF-TPAL: 2,3,5, 6-tetrafluoroterephthalaldehyde;
p-PDA: p-phenylenediamine;
m-TB: 4,4 '-diamino-2, 2' -dimethylbiphenyl, m-tolidine;
TFMB: 2,2' -bis (trifluoromethyl) diaminobiphenyl;
6 FAP: 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane;
6 FDAM: 2, 2-bis (4-aminophenyl) hexafluoropropane;
4-BDAF: 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane;
TAB: 1,3, 5-triaminobenzene;
TAPA: tris (4-aminophenyl) amine;
TAPB: 1,3, 5-tris (4-aminophenyl) benzene;
NMP: n-methyl pyrrolidone;
DNQ: diazo naphthoquinone.
[ examples 1 to 20 ]
[ polyimide composite resins A-T ] were prepared according to the raw material input in Table 1 and the following experimental procedures:
in a 100mL three-necked flask, quantitative amounts of diamine compounds and triamine compounds shown in Table 1 were dissolved in 40g of NMP under nitrogen atmosphere with stirring so that the sum of the mass percentages of the amine compounds was 5% to 13%. Then adding quantitative dimethyl aldehyde compounds shown in the table 1, controlling the temperature of the solution to be 0-50 ℃ under the nitrogen atmosphere, and reacting for 4-24 h. Then adding quantitative tetracarboxylic dianhydride compounds shown in the table 1 into the solution for three times, wherein the adding amount of each time respectively accounts for 60%, 30% and 10% of the total weight; continuously reacting for 4-48h under the nitrogen atmosphere, and controlling the solution temperature at 0-50 ℃. Finally obtaining the precursor solution of the polyimide composite resin.
The precursor solution of the polyimide composite resin was coated on a glass plate using a coater, and the film thickness of the polyimide composite resin after drying was about 10 to 30 um. Volatilizing for a certain time at 80-150 ℃ to ensure that the content of the solvent is between 15 and 25 percent, and obtaining the precursor dry film layer of the polyimide composite resin.
Thermally curing the glass plate coated with the polyimide composite resin precursor dry film layer at the temperature of 280-350 ℃ in the nitrogen atmosphere; the precursor dry film layer of the polyimide composite resin is cured to form a polyimide composite resin layer, and an insulating film base layer is formed.
And (3) removing the insulating film base layer from the glass plate by a water boiling method to obtain the polyimide composite resin film A-T with the low dielectric constant.
Comparative examples 21 to 22
Comparative [ polyimide resins U-V ] were prepared according to the raw material input amounts in table 1 and the following experimental procedure:
in a 100mL three-necked flask, a predetermined amount of the diamine compound shown in Table 1 was dissolved in 40g of NMP under nitrogen atmosphere with stirring so that the mass percentage of the amine compound was 5% to 8%. Then adding quantitative tetracarboxylic dianhydride compounds shown in the table 1 into the solution for three times, wherein the adding amount of each time respectively accounts for 60%, 30% and 10% of the total weight; the reaction was carried out for 48h under a nitrogen atmosphere, and the solution temperature was controlled at 25 ℃. Finally, a precursor solution of the polyimide resin is obtained.
The precursor solution of the polyimide resin was coated on a glass plate using a coater, and the film thickness of the polyimide resin after drying was about 10 to 30 um. Volatilizing at 150 ℃ for 10min to ensure that the content of the solvent is between 15 and 25 percent, and obtaining the precursor dry film layer of the polyimide resin.
Thermally curing the glass plate coated with the polyimide resin precursor dry film layer at 280 ℃ in a nitrogen atmosphere; the precursor dry film layer of the polyimide resin is cured to form a polyimide resin layer, forming an insulation film base layer.
And (3) taking off the insulating film base layer from the glass plate by a water boiling method to obtain the polyimide film U-V.
[ COMPARATIVE EXAMPLE 23 ]
Comparative [ polyimide composite resin W ] was prepared according to the raw material input amounts in table 1 and the following experimental procedures:
in a 100mL three-necked flask, 0.74g p-PDA and 3.28g of TFMB shown in Table 1 were dissolved in 40g of NMP under nitrogen atmosphere with stirring to give a total of 8% by mass of diamine compounds. Thereafter, 1.43g of BDAL shown in Table 1 was added, and the temperature of the solution was controlled to 0 ℃ under a nitrogen atmosphere, and the reaction was carried out for 4 hours. Then 4.55g of 6FDA shown in Table 1 is added into the solution in three times, and the adding amount of each time is respectively 60%, 30% and 10% of the total weight; the reaction was continued for 36h under nitrogen atmosphere with the solution temperature controlled at 0 ℃. Finally obtaining the precursor solution of the polyimide composite resin.
The precursor solution of the polyimide composite resin was coated on a glass plate using a coater, and the film thickness of the polyimide composite resin after drying was about 10 to 30 um. And volatilizing at 120 ℃ for 15min to ensure that the content of the solvent is 20 percent, thereby obtaining the precursor dry film layer of the polyimide composite resin.
Thermally curing the glass plate coated with the polyimide composite resin precursor dry film layer at 350 ℃ in a nitrogen atmosphere; the precursor dry film layer of the polyimide composite resin is cured to form a polyimide composite resin layer, and an insulating film base layer is formed.
And (3) taking off the insulating film base layer from the glass plate by a water boiling method to obtain the polyimide composite resin film W.
[ COMPARATIVE EXAMPLE 24 ]
[ Polyazomethine resin X ] was prepared according to the raw material input in Table 1 and the following experimental procedure:
in a 100mL three-necked flask, 1.14g p-PDA and 3.34g m-TB shown in Table 1 were dissolved in 40g of NMP under nitrogen atmosphere with stirring to give a total of 9% by mass of amine compounds. Thereafter, 5.52g of BDAL shown in Table 1 was added, and the solution was reacted for 20 hours under a nitrogen atmosphere at a controlled temperature of 20 ℃. Finally obtaining the precursor solution of the polymethine resin.
The precursor solution of the polyimide resin was coated on a glass plate using a coater, and the film thickness of the dried polyimide resin was about 10 to 30 um. And (3) volatilizing at 80 ℃ for 30min to ensure that the content of the solvent is 25 percent, thereby obtaining the precursor dry film layer of the poly-azomethine resin.
Thermally curing the glass plate coated with the polyimide resin precursor dry film layer at the temperature of 280 ℃ in the nitrogen atmosphere; the dry film layer of the precursor of the polyimide resin is cured to form a polyimide resin layer, forming an insulating film base layer.
And (3) peeling off the insulating film base layer from the glass plate by a water boiling method to obtain the polyimide resin film X.
Comparative example 25
[ Polyazomethine resin Y ] was prepared according to the raw material input in Table 1 and the following experimental procedure:
in a 100mL three-necked flask, 3.99g m-TB and 1.07g of TAPB shown in Table 1 were dissolved in 40g of NMP under nitrogen with stirring to give a total of 10% by mass of amine compounds. Thereafter, 4.94g of BDAL shown in Table 1 was added, and the temperature of the solution was controlled to 45 ℃ under a nitrogen atmosphere, and the reaction was carried out for 24 hours. Finally obtaining the precursor solution of the polymethine resin.
The precursor solution of the polyimide resin was coated on a glass plate using a coater, and the film thickness of the dried polyimide resin was about 10 to 30 um. And volatilizing at 100 ℃ for 15min to ensure that the content of the solvent is 22 percent, thereby obtaining the precursor dry film layer of the poly-azomethine resin.
Thermally curing the glass plate coated with the polyimide resin precursor dry film layer at 320 ℃ in a nitrogen atmosphere; the dry film layer of the precursor of the polyimide resin is cured to form a polyimide resin layer, forming an insulating film base layer.
And (3) peeling off the insulating film base layer from the glass plate by a water boiling method to obtain the final polyimide resin film Y.
Table 1: raw material addition amount in examples and comparative examples
The advantages of the low dielectric constant polyimide composite resin of the present invention in terms of dielectric constant, mechanical properties, thermal expansion coefficient, etc. are illustrated by comparing the properties of examples with those of comparative examples.
The polyimide composite resins A to T of examples 1 to 20 and the polyimide resins U to V, the polyimide composite resin W and the polyimide resins X to Y of comparative examples 21 to 25 were subjected to performance tests under the following specific test conditions and methods:
the dielectric constant and dielectric loss are tested on a wide-temperature wide-frequency impedance analyzer of ONTROL at NOV ℃ in Germany, and the testing frequency is from 100Hz to 1 GHz.
Tensile strength and elongation at break were measured in a universal tester by the IPC-TM-6502.4.18B method.
Coefficient of thermal expansion, measured on a Q400TMA test instrument from TA, USA.
The properties of the films obtained by the test are shown in Table 2 below.
TABLE 2 comparison of Properties of resin films obtained in examples 1 to 20 and comparative examples 21 to 25
As can be seen from Table 2, the dielectric constant of the present invention is significantly reduced after blending and copolymerizing the polyimide resin and the polyimide resin: the dielectric constant of the conventional polyimide resin (U-V sample) is 3.3 to 3.4; after blending and copolymerization of the polyimide, the dielectric constant of the polyimide composite resin is reduced to below 3, and some dielectric constants are even reduced to 2.5. This is due to the fact that, after the copolymerization of the polymethine resin, the dipole moment of the molecular chain is reduced; also benefit from the use of fluoromonomers.
In addition, the rigidity of the polyethyleneimine molecular chain was too high, and although a partial film could be obtained in the comparative example, the film was very likely to crack, and directional fiberization was observed; after the triamine compound is added into the formula, the mechanical property after film forming is improved, and the polyethyleneimine modified resin Y with the tensile strength of 110MPa can be obtained. Further, it was also found that the CTE of the polyimide modified resin Y was also small, owing to the high rigidity of its molecular chain. The triamine compound monomer is added into the polyimide composite resin, so that the effect of improving the rigidity of a molecular chain is achieved, and the mechanical property of the polyimide resin is prevented from meeting the application requirement of a product.
The addition of the triamine compound can also reduce the dielectric constant of the polyimide composite resin to a certain extent. The dielectric constant of the polyimide composite resin H, P, Q, S is substantially 2.5 or less, when the amount of the triamine compound monomer added is high. Although the fluorine-containing monomer and the polyimide resin also act together, the dielectric constants of the composite resins are obviously lower than those of other samples, which can show that the triamine compounds still contribute to the reduction of the dielectric constant.
The specific implementation mode for preparing the single-sided flexible copper-clad plate is as follows:
(1) preparing a precursor solution. Precursor solutions of polyimide composite resins were prepared according to examples 1 to 20;
(2) uniformly coating the precursor solution of the polyimide composite resin obtained in the step (1) on a copper foil with the thickness of 12-105um, and enabling the film thickness of the dried polyimide composite resin to be about 5-35 um. And (3) putting the polyimide composite resin into an oven at the temperature of 80-150 ℃, keeping the temperature for a certain time, and volatilizing to remove the solvent to ensure that the content of the solvent is between 15 and 25 percent to obtain the precursor dry film layer of the polyimide composite resin. And (3) putting the copper foil sample into a 280-plus-350-DEG C high-temperature nitrogen oven, and performing thermocuring according to a certain temperature rise program to prepare the flexible copper clad laminate substrate coated with the polyimide composite resin layer on the copper foil.
In the step (2), the copper foil can be coated with one polyimide composite resin, and can also be coated with a plurality of polyimide resins to improve other performances of the flexible copper clad laminate. When a plurality of polyimide resins are coated, a precursor solution of a first polyimide composite resin is coated and the solvent is evaporated, and then a precursor solution of a second polyimide composite resin is coated and the solvent is evaporated. The solvent volatilization conditions can be optimized by selecting the conditions listed in step (2). After the solvent is volatilized, putting the sample into a high-temperature nitrogen oven at the temperature of 280-350 ℃, performing thermal curing by a certain temperature-rising program, and performing thermal curing on the precursor dry films of the first polyimide composite resin and the second polyimide composite resin or other polyimide composite resins to obtain the flexible copper-clad plate base material coated with the polyimide composite resin layers on the copper foil.
The specific implementation mode for preparing the double-sided flexible copper-clad plate is as follows:
(1) preparing a precursor solution, which comprises the following substeps;
(1.1) preparing a precursor solution of a polyimide composite resin according to examples 1 to 20;
(1.2) preparing a precursor solution of a thermoplastic polyimide resin: under a nitrogen atmosphere, 1.00g of 1, 3-bis (3-aminophenoxy) benzene and 3.99g of 1, 3-bis (4-aminophenoxy) benzene were added to 40g of an NMP solvent and stirred until completely dissolved; then 5.02g of BPDA was added in three portions, followed by stirring for about 24 h; preparing a precursor solution of the thermoplastic polyimide resin;
(2) and preparing the pressable substrate. And (2) uniformly coating the precursor solution of the polyimide composite resin obtained in the step (1.1) on a copper foil with the thickness of 12-105um, and enabling the film thickness of the dried polyimide composite resin to be about 5-35 um. And (3) putting the polyimide composite resin into an oven at the temperature of 80-150 ℃, keeping the temperature for a certain time, and volatilizing to remove the solvent to ensure that the content of the solvent is between 15 and 25 percent to obtain the precursor dry film layer of the polyimide composite resin. Then, the precursor solution of the thermoplastic polyimide resin obtained in step (1.2) is further coated on the dry film precursor of the polyimide composite resin so that the film thickness of the thermoplastic polyimide resin after drying is about 0.5 to 3 um. Putting the mixture into an oven at the temperature of 80-150 ℃, keeping the mixture for a certain time, volatilizing to remove the solvent to ensure that the content of the solvent is between 15 and 25 percent, and forming a precursor dry film layer of the thermoplastic polyimide resin. And (3) putting the copper foil sample into a 280-350 ℃ high-temperature nitrogen oven, and performing thermosetting through a certain temperature rise procedure to prepare the pressable substrate coated with the polyimide composite resin layer and the thermoplastic polyimide resin layer on the copper foil.
(3) And (3) pressing and preparing the double-sided flexible copper-clad plate. Taking 2 laminated substrates obtained in the step (2), symmetrically laminating, and mutually contacting thermoplastic polyimide resin layers; and laminating for 10min at the temperature of 350 ℃ and under the pressure of 20Mpa to obtain the double-sided flexible copper-clad plate.
In the step (3), in addition to symmetrically attaching 2 same laminated substrates, 1 laminated substrate obtained in the step (2) and a copper foil can be attached to each other, and the thermoplastic polyimide resin layer and the other 1 copper foil are attached to each other in a contact manner; and laminating for 10min at the temperature of 350 ℃ and under the pressure of 20Mpa to obtain the double-sided flexible copper-clad plate.
Specific embodiments of the preparation of the positive photosensitive cover film are as follows:
(1) preparing a precursor solution of the polyimide composite resin according to the embodiments 1 to 20;
(2) adding diazonaphthoquinone DNQ into the precursor solution of the polyimide composite resin prepared in the step (1) to ensure that the weight percentage of DNQ in the final positive photosensitive cover film is 10-40%; after adding, controlling the temperature of the solution to be 0-50 ℃ under the nitrogen atmosphere, and continuously stirring for 4-24 h;
(3) preparing a film from the photosensitive mixture solution obtained in the step (2): coating the solution on a glass plate or other carriers to make the film thickness of the dried photosensitive mixture about 5-50 um; then volatilizing for a certain time at 60-90 ℃ to ensure that the content of the solvent is between 2-15 percent, and obtaining a photosensitive mixture film, namely the positive photosensitive covering film.
And (4) carrying out pattern exposure on the positive photosensitive covering film obtained in the step (3) through a film under the irradiation of light with a certain wavelength. Then developing in 0.1% by weight of tetramethylammonium hydroxide aqueous solution for 2-20 min. Suitable exposure energy, exposure time and development time are preferred so that areas not masked by the film are developed and removed completely, but areas protected by the film mask are left intact to obtain the desired pattern. And then, putting the cover film sample into a high-temperature nitrogen oven at the temperature of 280-350 ℃, and performing thermal curing by a certain temperature rise program to obtain a patterned cover film product required by the field of PCB/FPC.
In the above embodiments, there is no limitation on the content and formula of the polyimide composite resin of the present invention, and there is no limitation on the parameter conditions adopted when the polyimide composite resin is used to prepare the single-sided flexible copper clad laminate and the double-sided flexible copper clad laminate, and all the minor modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention are still within the scope of the technical solution of the present invention.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby. Any insubstantial changes and substitutions made by those skilled in the art based on the present invention are intended to be covered by the claims.