Inkjet ink, cured product, and method for forming cured film

Abstract

Provided is an inkjet ink having good room temperature stability due to using a monomer composition containing: a half ester (A) that can be obtained by reacting at least one acid dianhydride with an alcohol; a diamine (B); and a solvent (C). The good room temperature stability of the inkjet ink enables easy handling during production, supply, and distribution, and the inkjet ink can achieve a higher solid content compared to polyamic acid due to having a lower viscosity than polyamic acid.

Description

Inkjet ink, cured product, and method for forming a cured film

[0001] The present invention relates to an inkjet ink, a cured product, and a method for forming a cured film.

[0002] In the field of electronic components used in electronic communications and the like, various materials have been developed in response to the increasing integration of semiconductor chips, which correspond to the miniaturization and high performance of devices. For example, Patent Document 1 describes a composition containing an amine containing an SiO bond, such as a silane coupling agent, which has a low thermal expansion coefficient and excellent bonding strength to a substrate. In semiconductor chip manufacturing methods, patterns are generally formed using an etching resist material. In complex package structures such as MEMS (Micro Electro Mechanical Systems), when applying an etching resist material to specific locations, general photolithography is difficult to achieve, so inkjet printing, which forms a desired pattern film using an inkjet, is useful.

[0003] In order to eject and print inkjet inks, various parameters such as viscosity must be considered and adjusted. For example, in polyimide-based inkjet inks, because polyamic acid is a polymer, the proportion of solvent must be increased and the proportion of polyamic acid must be decreased to achieve optimal viscosity. However, decreasing the proportion of polyamic acid poses the problem of a thin film obtained in a single jetting run. Therefore, it has been proposed to lower the viscosity of the ink by controlling the weight-average molecular weight of the polyamic acid to 10,000 to 50,000 and increase the polyamic acid content (see, for example, Patent Document 2).

[0004] International Publication No. 2022 / 054839 Japanese Patent Application Laid-Open No. 2005-187596

[0005] The composition described in Patent Document 2 contains polyamic acid, which has poor room temperature stability and is sensitive to environmental temperatures, making it difficult to produce stably. Another problem is that the high viscosity of polyamic acid requires a low concentration. The present invention aims to provide an inkjet ink, a cured product, and a method for forming a cured film that have good room temperature stability, are easy to produce stably, and have a lower viscosity than polyamic acid, allowing for a high concentration of solids other than the solvent.

[0006] The present inventors have conducted extensive research and have completed the present invention, which comprises the following technical means.

[0007] [1] An inkjet ink comprising a half ester (A), a diamine (B), and a solvent (C). [2] The inkjet ink according to [1], wherein the molar ratio of the half ester (A):the diamine (B) is 1:0.5 or more and 1:2 or less.

[0008] [3] The ink-jet ink according to [1] or [2], wherein the half ester (A) is represented by formula (1a) or (1b). (R in formula (1a) or formula (1b) 1 is an organic group having 2 to 100 carbon atoms and an aliphatic hydrocarbon structure, or an organic group having 2 to 100 carbon atoms and an unsaturated hydrocarbon structure, and R 2 are independently alkyl having 1 to 30 carbon atoms or phenyl in which at least one hydrogen may be replaced by -F, -CH3, -OCH3, -OCH2F, -OCHF2, or -OCF3, and in the alkyl having 1 to 30 carbon atoms and alkyl having 1 to 10 carbon atoms, at least one -CH2- may be replaced by -CF2-, -CHF-, -O-, -CH=CH-, or -C≡C-, and at least one -CH3 may be replaced by -CH2F, -CHF2, or -CF3.

[0009] [4] The ink-jet ink according to [1] or [2], wherein the half ester (A) is represented by formula (1a) or (1b). (R in formula (1a) and formula (1b)1 is an organic group having one or two benzene rings or an organic group having one or two cyclohexane rings, and R in formula (1a) and formula (1b) 2 are independently methyl or ethyl.

[0010] [5] The ink-jet ink according to any one of [1] to [4], wherein the diamine (B) is represented by formula (2): (R in formula (2) 3 is an organic group having an unsaturated hydrocarbon structure and having 2 to 100 carbon atoms.

[0011] [6] The ink-jet ink according to any one of [1] to [4], wherein the diamine (B) is represented by formula (2): (R in formula (2) 3 is an organic group having one, two or three benzene rings.

[0012] [7] The ink-jet ink according to any one of [1] to [4], wherein the diamine (B) has one or more phenolic hydroxyl groups and / or carboxylic acid groups.

[0013] [8] The ink-jet ink according to any one of [1] to [7], wherein the half ester (A) is a half ester obtained by reacting at least one selected from the group consisting of pyromellitic anhydride (PMDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA), 4,4'-biphthalic anhydride (s-BPDA), 3,4'-biphthalic anhydride (a-BPDA), 4,4'-oxydiphthalic anhydride (ODPA), and dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (HBPDA) with an alcohol.

[0014] [9] The ink-jet ink according to any one of [1] to [8], wherein the diamine (B) is at least one selected from the group consisting of 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)sulfone, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 5,5'-methylenebis(2-aminobenzoic acid), 3,5-bis(4-aminophenoxy)benzoic acid, and 3,5-diaminobenzoic acid.

[0015]

[10] A cured product obtained by heating the inkjet ink according to any one of [1] to [9].

[11] A method for forming a cured film, comprising the steps of applying the inkjet ink according to any one of [1] to [9] by an inkjet coating method and then drying the applied ink to form a film, and heating the film to form a cured film.

[0016] The ink-jet ink of the present invention is prepared by dissolving the half ester (A) and diamine (B) monomers in the solvent (C), and therefore has good viscosity stability at room temperature, making it possible to stably produce the ink-jet ink. Furthermore, since the viscosity is lower than that of ink-jet inks containing polyamic acid, the solid content other than the solvent can be increased in concentration.

[0017] 1 is a schematic diagram showing a photolithography process; 2 is a schematic diagram showing an example of a complex package structure; 3 is a schematic diagram showing a method for etching resistance and alkali peelability testing; 4 is a photograph substituting for a drawing showing the results of etching resistance and alkali peelability testing for one example; and 5 is a graph showing the results of a storage stability test.

[0018]

[0023] The present invention will be described below with reference to the accompanying drawings, in which:

[0024] Figure 1 is a schematic diagram showing a photolithography process;

[0025] In the manufacture of semiconductor chips, photolithography is generally performed to form a pattern using an etching resist material.

[0019] In photolithography, a film to be processed 2 is formed on a substrate (wafer) 1, a resist (etching resist material) 3 is applied in a resist coating process, and the resist 3 is heated in a pre-bake process. Thereafter, an exposure process is performed using a mask 4, and the resist is removed in the exposed portions (positive resist) or unexposed portions (negative resist) in a development process to expose the film to be processed 2. Then, a post-bake process is performed followed by an etching process to remove the exposed portions of the film to be processed 2, and the resist 3 covering the film to be processed 2 is then removed in a resist removal process. When photolithography is used, a pattern of the film to be processed 2 is formed on the substrate 1 as described above.

[0020] 2 is a schematic diagram showing an example of a complex package structure. In the case of a complex package structure, it is difficult to form a pattern of the film 2 to be processed on the substrate 1 using the general photolithography method described above, so inkjet printing, which can apply resist 3 to specific locations, is useful.

[0021] By using inkjet printing, a resist 3 is applied to a predetermined location on the workpiece film 2 by an inkjet process, the resist 3 is hardened, and then the parts of the workpiece film 2 that are not covered with the resist 3 are removed by etching using acid, and then the resist 3 is removed using alkali, thereby forming a pattern of the workpiece film 2 on the substrate 1.

[0022] Conventional polyimide-based inkjet inks have the problem of poor room temperature stability due to the inclusion of polyamic acid (amic acid). As shown using the schematic chemical formula below, in inkjet inks containing polyamic acid, polyamic acid is synthesized from a monomer, and a reversible reaction occurs between the synthesized polyamic acid, an intermediate, and the monomer. Therefore, when inkjet inks containing polyamic acid are stored at room temperature, the proportion of polyamic acid decreases, resulting in a decrease in viscosity.

[0023] The inventors have found that the room temperature stability of an ink-jet ink can be improved by using a composition of a half-esterified acid dianhydride and a diamine instead of a polyamic acid. That is, as shown in the following schematic chemical formula, by using a composition of monomers containing the half ester (A) and diamine (B) of the present invention, it is possible to suppress changes in viscosity when the ink-jet ink is stored at room temperature.

[0024] As described above, many conventional inkjet inks containing polyamic acid are sensitive to environmental temperature, making stable production difficult. However, the inkjet ink of the present invention uses a composition of half ester (A) and diamine (B), which makes it possible to suppress the influence of environmental temperature and ensure stable production.

[0025] Furthermore, since the inkjet ink of the present invention does not contain polyamic acid, which causes high viscosity, it has low viscosity, and the solid content can be increased by increasing the contents of half ester (A) and diamine (B).

[0026] For example, the solids concentration and viscosity are significantly different when a polyamic acid produced from pyromellitic anhydride (PMDA) and 3,3'-dihydroxybenzidine (HAB) in a molar ratio of 1:1 is used, and when a composition is used in which PMDA-ME, in which PMDA is converted into a half ester (A) with methanol, and HAB as a diamine (B) are mixed in a molar ratio of 1:1.

[0027] When the above polyamic acid was dissolved in KJCMPA (registered trademark)-100 (manufactured by KJ Chemicals Co., Ltd.) at a solids concentration of 10% by weight, the viscosity was 32,250 (mPa·s). In contrast, when a composition of PMDA-ME and HAB was dissolved in KJCMPA-100 at a solids concentration of 20% by weight, the viscosity was 12 (mPa·s). In this way, by using a monomer composition of half ester (A) and diamine (B) in place of polyamic acid, the viscosity of the inkjet ink can be reduced and the solids concentration can be increased.

[0028] The inkjet ink of the present invention contains the half ester (A), the diamine (B), and the solvent (C), and therefore is an inkjet ink that is stable at room temperature, has a low viscosity suitable for inkjet ejection, has a high solids concentration, and provides a cured film with excellent etching resistance and releasability (solubility).

[0029] (Half Ester (A)) The half ester (A) is a compound obtained by reacting an acid dianhydride with an alcohol, and examples thereof include the compounds represented by formula (1a) or (1b) described in the section "Means for Solving the Problems." The compound represented by formula (1b) includes the compound represented by the following formula (1b').

[0030] The half ester (A) may be used alone or in combination of two or more thereof, as well as the diamine (B), solvent (C), and other components described below.

[0031] (Synthesis of Half Ester (A)) The half ester (A) can be synthesized using an acid dianhydride and an alcohol. (In the above chemical formula, R represents a hydrocarbon group such as methyl or ethyl.)

[0032] Specific examples of the acid dianhydride used in the synthesis of the half ester (A) include copolymers of a radically polymerizable monomer having an anhydride group with another radically polymerizable monomer, such as a styrene-maleic anhydride copolymer and a methyl methacrylate-maleic anhydride copolymer, and tetracarboxylic acid dianhydride. Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,2',3,3'-diphenylsulfone tetracarboxylic dianhydride, 2,3,3',4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-diphenylether tetracarboxylic dianhydride, 2,2',3,3'-diphenylether tetracarboxylic dianhydride, 2,3,3',4'-diphenylether tetracarboxylic dianhydride, 2,2-[bis(3,4-dicarboxyphenyl)]hexafluoropropane dianhydride, Water, ethylene glycol bis(anhydrotrimellitate), cyclobutane tetracarboxylic dianhydride, methylcyclobutane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, ethane tetracarboxylic dianhydride and butane tetracarboxylic dianhydride, p-phenylene bis(trimellitic acid monoester anhydride), 4,4'-[(isopropylidene)bis(p-phenyleneoxy)]diphthalic dianhydride, ethylenediaminetetraacetic dianhydride, 3,3',4,4'-bicyclohexyl tetracarboxylic dianhydride, 3,3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene succinic dianhydride, tetracarboxylic dianhydrides such as compounds represented by the following formulas a1-1 to a1-73, and the like.

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] The half ester (A) is preferably a half ester obtained by reacting at least one of pyromellitic anhydride (PMDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA), 4,4'-biphthalic anhydride (s-BPDA), 3,4'-biphthalic anhydride (a-BPDA), 4,4'-oxydiphthalic anhydride (ODPA), and dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (HBPDA) with an alcohol.

[0047] The acid dianhydride used as a raw material for the half ester (A) is not limited to the acid dianhydride described in this embodiment, and various other forms of acid dianhydrides can be used as long as the object of the present invention is achieved.

[0048] (Diamine (B)) The diamine (B) is not particularly limited as long as it has two amino groups, and examples thereof include those represented by formula (2) described in the section on means for solving the problems.

[0049] From the viewpoint of obtaining an inkjet ink that forms a cured product that exhibits good etching resistance and alkali removability, the diamine (B) preferably has at least one phenolic hydroxyl group or carboxylic acid group.

[0050] Examples of the diamine (B) having one or more phenolic hydroxyl groups or carboxylic acid groups include 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)sulfone, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 5,5'-methylenebis(2-aminobenzoic acid), 3,5-bis(4-aminophenoxy)benzoic acid, and 3,5-diaminobenzoic acid.

[0051] Examples of the diamine (B) include 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, p-xylylenediamine, 2,2'-diaminodiphenylpropane, benzidine, 1,1-bis[4-(4-aminobenzyl)phenyl]methane, and compounds represented by the following formulas (II) to (VIII).

[0052]

[0053] In formula (II), A 1 is -(CH2) m -, where m is an integer of 1 to 6. In formulas (IV), (VI) and (VIII), A 1 represents a single bond, -O-, -S-, -S-S-, -SO2-, -CO-, -CONH-, -NHCO-, -C(CH3)2-, -C(CF3)2-, -(CH2) m -, -O-(CH2) m -O-, -S-(CH2) m -S-, where m is an integer of 1 to 6. In formulas (VII) and (VIII), A 2is a single bond, —O—, —S—, —CO—, —C(CH3)2—, —C(CF3)2— or alkylene having 1 to 3 carbon atoms, and a hydrogen atom bonded to the cyclohexane ring or the benzene ring may be replaced with —F or —CH3.

[0054] Examples of the diamine represented by formula (II) include diamines represented by formulas (II-1) to (II-3).

[0055]

[0056] Examples of the diamine represented by formula (III) include diamines represented by formulas (III-1) and (III-2).

[0057]

[0058] Examples of the diamine represented by formula (IV) include diamines represented by the following formulas (IV-1) to (IV-3).

[0059]

[0060] Examples of the diamine represented by formula (V) include diamines represented by formulas (V-1) to (V-5).

[0061]

[0062] Examples of the diamine represented by formula (VI) include diamines represented by formulas (VI-1) to (VI-30).

[0063]

[0064]

[0065]

[0066]

[0067]

[0068] Examples of the diamine represented by formula (VII) include diamines represented by formulas (VII-1) to (VII-6).

[0069]

[0070] Examples of the diamine represented by formula (VIII) include diamines represented by the following formulae (VIII-1) to (VIII-11).

[0071]

[0072]

[0073] The diamine (B) further includes a diamine represented by formula (IX). In formula (IX), A3 is a single bond, —O—, —COO—, —OCO—, —CO—, —CONH—, or —(CH2) p -, where p is an integer from 1 to 6. In formula (IX), R 6 is a group having at least one ring structure selected from the group consisting of a group having a steroid skeleton, a cyclohexane ring, and a benzene ring, and when the positions of the two amino groups bonded to the benzene ring are para-positioned, R 6 may be alkyl having 1 to 30 carbon atoms, or when the positional relationship is meta, may be alkyl having 1 to 10 carbon atoms or phenyl optionally substituted with -F, -CH3, -OCH3, -OCH2F, -OCHF2 or -OCF3, and in the alkyl having 1 to 30 carbon atoms and alkyl having 1 to 10 carbon atoms, any -CH2- may be replaced with -CF2-, -CHF-, -O-, -CH=CH- or -C≡C-, and any -CH3 may be replaced with -CH2F, -CHF2 or -CF3.

[0074] In formula (IX), the two amino groups are bonded to the carbon atoms of the phenyl ring, and the bonding position of the two amino groups is preferably meta or para. 6 -A 3 When the bonding position of "-" is considered to be position 1, it is preferable that they are bonded to positions 3 and 5, or positions 2 and 5. Examples of diamines represented by formula (IX) include diamines represented by formulas (IX-1) to (IX-11).

[0075]

[0076]

[0077] In formulas (IX-1), (IX-2), (IX-7) and (IX-8), R 18 is an organic group having 1 to 30 carbon atoms, and among these, alkyl having 3 to 12 carbon atoms or alkoxy having 3 to 12 carbon atoms is preferred, and alkyl having 5 to 12 carbon atoms or alkoxy having 5 to 12 carbon atoms is more preferred. 19 is an organic group having 1 to 30 carbon atoms, and among these, alkyl having 1 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms is preferred, and alkyl having 3 to 10 carbon atoms or alkoxy having 3 to 10 carbon atoms is more preferred.

[0078] Further examples of the diamine represented by formula (IX) include diamines represented by the following formulae (IX-12) to (IX-17).

[0079]

[0080] In formulas (IX-12) to (IX-15), R 20 is an organic group having 1 to 30 carbon atoms, preferably an alkyl group having 4 to 16 carbon atoms, and more preferably an alkyl group having 6 to 16 carbon atoms. 21 is an organic group having 1 to 30 carbon atoms, preferably an alkyl group having 6 to 20 carbon atoms, and more preferably an alkyl group having 8 to 20 carbon atoms.

[0081] Further examples of the diamine represented by formula (IX) include diamines represented by the following formulae (IX-18) to (IX-38).

[0082]

[0083]

[0084]

[0085] In the above formulas (IX-18), (IX-19), (IX-22), (IX-24), (IX-25), (IX-28), (IX-30), (IX-31), (IX-36) and (IX-37), R 22 is an organic group having 1 to 30 carbon atoms, preferably an alkyl having 1 to 12 carbon atoms or an alkoxy having 1 to 12 carbon atoms, and more preferably an alkyl having 3 to 12 carbon atoms or an alkoxy having 3 to 12 carbon atoms. In addition, in the above formulae (IX-20), (IX-21), (IX-23), (IX-26), (IX-27), (IX-29), (IX-32) to (IX-35) and (IX-38), R 23 is hydrogen, -F, alkyl having 1 to 12 carbon atoms, alkoxy having 1 to 12 carbon atoms, -CN, -OCHF, -OCHF or -OCF, and preferably alkyl having 3 to 12 carbon atoms or alkoxy having 3 to 12 carbon atoms. 9 is alkylene having 1 to 12 carbon atoms.

[0086] Further examples of the diamine represented by formula (IX) include diamines represented by the following formulae (IX-39) to (IX-48).

[0087]

[0088]

[0089] Among the diamines represented by formula (IX), diamines represented by formulas (IX-1) to (IX-11) are preferred, and diamines represented by formulas (IX-2), (IX-4), (IX-5) and (IX-6) are more preferred.

[0090] Further examples of the diamine (B) include compounds represented by the following formulas (XI) and (XII).

[0091] In formulas (XI) and (XII), R 10 is hydrogen or —CH3, and R 11 are each independently hydrogen, alkyl having 1 to 20 carbon atoms, or alkenyl having 2 to 20 carbon atoms; A 6are each independently a single bond, —C(═O)—, or —CH—. In formula (XII), R 13 and R 14 are each independently hydrogen, alkyl having 1 to 20 carbon atoms, or phenyl.

[0092] In formula (XI), two "NH2-Ph-A 6 Preferably, one of the —O— (-Ph- represents phenylene) is bonded to the 3-position of the steroid nucleus, and the other is bonded to the 6-position. In addition, the two amino groups are each bonded to a carbon atom of the phenyl ring, and A 6 It is preferable that the diamine represented by formula (XI) is bonded at the meta or para position relative to the bonding position of formula (XI). Examples of the diamine represented by formula (XI) include diamines represented by formulas (XI-1) to (XI-4).

[0093]

[0094] In formula (XII), two "NH2-(R 14 -) Ph-A 6 Each of the —O— (-Ph- represents phenylene) is bonded to a carbon atom on the phenyl ring, preferably at a meta or para position relative to the carbon atom to which the steroid nucleus is bonded. Also, each of the two amino groups is bonded to a carbon atom on the phenyl ring, preferably at a para or meta position relative to the carbon atom to which the steroid nucleus is bonded. 6 It is preferable that the diamine is bonded to the meta or para position relative to the diamine represented by formula (XII). Examples of the diamine represented by formula (XII) include diamines represented by formulas (XII-1) to (XII-8).

[0095]

[0096]

[0097] Further examples of the diamine (B) in this embodiment include compounds represented by formulas (XIII) and (XIV).

[0098] In formula (XIII), R 15is hydrogen or alkyl having 1 to 20 carbon atoms, and any —CH— in the alkyl having 2 to 20 carbon atoms may be replaced by —O—, —CH═CH— or —C≡C—; A 7 are each independently —O— or alkylene having 1 to 6 carbon atoms; A 8 represents a single bond or alkylene having 1 to 3 carbon atoms; ring T represents 1,4-phenylene or 1,4-cyclohexylene; and h represents 0 or 1.

[0099] In formula (XIV), R 16 is alkyl having 2 to 30 carbon atoms, and among these, alkyl having 6 to 20 carbon atoms is preferred. 17 is hydrogen or alkyl having 1 to 30 carbon atoms, and among these, alkyl having 1 to 10 carbon atoms is preferred. 7 are each independently —O— or alkylene having 1 to 6 carbon atoms.

[0100] In formula (XIII), two amino groups are bonded to the phenyl ring carbons, but A 7 Examples of the diamine represented by formula (XIII) include 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-methylcyclohexane, 1,1-bis[4-(4-aminobenzyl)phenyl]cyclohexane, 1,1-bis[4-(4-aminobenzyl)phenyl]4-methylcyclohexane, and diamines represented by formulas (XIII-1) to (XIII-9).

[0101]

[0102]

[0103] In formula (XIV), two amino groups are bonded to the phenyl ring carbons, but A 7 It is preferable that the diamine represented by formula (XIV) is bonded at the meta or para position relative to the diamine represented by formula (XIV), for example, diamines represented by formulas (XIV-1) to (XIV-3).

[0104] In formulas (XIV-1) to (XIV-3), R 26 is alkyl having 2 to 30 carbon atoms, and among these, alkyl having 6 to 20 carbon atoms is preferred, and R 27 is hydrogen or alkyl having 1 to 30 carbon atoms, and among these, hydrogen or alkyl having 1 to 10 carbon atoms is preferred.

[0105] As described above, the diamine (B) may be, for example, a diamine represented by any one of formulas (I) to (XIV), but diamines other than these may also be used. For example, a naphthalene-based diamine having a naphthalene structure, a fluorene-based diamine having a fluorene structure, or a siloxane-based diamine having a siloxane bond may be used alone or in combination with other diamines.

[0106] In formula (4), R 5 and R 6 are independently alkyl or phenyl having 1 to 3 carbon atoms, and R 7 are independently methylene, phenylene, or phenylene in which at least one hydrogen is replaced by alkyl; x is independently an integer of 1 to 6; and y is an integer of 1 to 70.

[0107] Further, examples of the diamine (B) include diamines represented by the following formulas (11) to (18): 30 and R 31 are independently alkyl having 3 to 20 carbon atoms.

[0108]

[0109] The diamine (B) is not limited to the diamine described in this embodiment, and various other forms of diamine can be used within the scope of achieving the object of the present invention.

[0110] (Molar Ratio) From the viewpoint of obtaining an inkjet ink that forms a cured product exhibiting good etching resistance and alkali removability, the molar ratio of the half ester (A) to the diamine (B) is preferably 1:0.5 or more and 1:2 or less, and more preferably 1:0.7 or more and 1:1.1 or less.

[0111] (Solvent (C)) The solvent (C) of the inkjet ink is not particularly limited as long as it can dissolve the half ester (A) and the diamine (B). Even if a solvent does not dissolve these components alone, it can be used as the solvent (C) contained in the inkjet ink by mixing it with another solvent.

[0112] Specific examples of the solvent (C) contained in the inkjet ink include 3-methoxy-N,N-dimethylpropanamide, N,N-dimethylacetamide, ethyl lactate, ethanol, ethylene glycol, propylene glycol, glycerin, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, cyclohexanone, 1,3-dioxolane, ethylene glycol dimethyl ether, 1,4-dioxane, propylene glycol dimethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, anisole, ethyl lactate, dipropylene glycol dimethyl ether, diethylene glycol isopropyl methyl ether, dipropylene Glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, triethylene glycol monomethyl ether, diethylene glycol dibutyl ether, propylene glycol monobutyl ether (1-butoxy-2-propanol), propylene glycol monoethyl ether (1-ethoxy-2-propanol), propylene glycol monomethyl ether (1-methoxy-2-propanol), triethylene glycol divinyl ether, tripropylene glycol monomethyl ether, tetramethylene glycol monovinyl ether, methyl benzoate, ethyl benzoate, 1-vinyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1-acetyl-2-pyrrolidone, N,N-diethylacetamide, N,Examples include N-dimethylpropionamide, N-methyl-ε-caprolactam, 1,3-dimethyl-2-imidazolidinone, and γ-butyrolactone.

[0113] The solvent (C) is preferably added and used so that the solid content concentration in the ink-jet ink is 10 to 50% by weight.

[0114] (Solid Content Concentration) The solid content concentration in the inkjet ink of the present invention is not particularly limited, but is preferably 10 to 50 parts by weight per 100 parts by weight of the inkjet ink. The solid content refers to components that constitute a cured product when the ink is cured by heating.

[0115] (Additives) Depending on the desired properties, the inkjet ink can be obtained by selecting and adding additives such as epoxy resins, acrylic resins, surfactants, antistatic agents, coupling agents, epoxy curing agents, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, antireducing agents, evaporation accelerators, chelating agents, water-soluble polymers, pigments, dyes, and imidizing agents as necessary, and mixing and dissolving them uniformly.

[0116] Examples of surfactants that may be added to inkjet inks from the viewpoint of improving coating properties include polyether-modified surfactants such as the KP series (manufactured by Shin-Etsu Chemical Co., Ltd.) under the trade name "KP-341"; silicone-based surfactants such as those under the trade names "Byk-300," "Byk-306," "Byk-335," "Byk-310," "Byk-341," "Byk-344," and "Byk-370" (manufactured by BYK-Chemie Co., Ltd.), "Silaplane FM-3311," "Silaplane FM-3321," and "Silaplane FM-3325" (manufactured by JNC Corporation); and acrylic-based surfactants such as those under the trade names "Byk-354," "ByK-358," and "Byk-361" (manufactured by BYK-Chemie Co., Ltd.). Surfactants include fluorine-based surfactants such as those under the trade names "DFX-18," "Ftergent 250," and "Ftergent 251" (manufactured by Neos Corporation), "Megafac F-410," "Megafac F-430," "Megafac F-444," "Megafac F-472SF," "Megafac F-475," "Megafac F-477," "Megafac F-552," "Megafac F-553," "Megafac F-554," "Megafac F-555," "Megafac F-556," "Megafac F-558," "Megafac F-563," "Megafac R-94," "Megafac RS-75," and "Megafac RS-72-K" (manufactured by DIC Corporation). Surfactants are used to improve wettability, leveling, or coatability to the underlying substrate, and are preferably added in an amount of 0.01 to 1 part by weight per 100 parts by weight of the ink-jet ink.

[0117] (Viscosity of Inkjet Ink) In the present invention, the viscosity of the inkjet ink is not particularly limited, but when jetting is performed at room temperature (25°C), a viscosity of 1 to 50 mPa·s is preferred in terms of improving the jetting accuracy by the inkjet coating method. Furthermore, the viscosity of the inkjet ink at 25°C is more preferably 5 to 30 mPa·s, and even more preferably 8 to 15 mPa·s (25°C). If the viscosity is less than 15 mPa·s (25°C), inkjet ejection defects will not occur.

[0118] When jetting is performed by heating the ink head, the viscosity of the inkjet ink at the heating temperature (preferably 40 to 120° C.) is preferably 1 to 50 mPa·s, more preferably 5 to 30 mPa·s, and particularly preferably 8 to 15 mPa·s. If the viscosity at the heating temperature is less than 15 mPa·s, poor inkjet ejection will not occur.

[0119] (Surface Tension of Inkjet Ink) The surface tension of the inkjet ink of the present invention is usually 20 to 70 mN / m, and preferably 20 to 40 mN / m. When the surface tension is in this range, good droplets can be formed by jetting, and a meniscus can be formed.

[0120] (Cured Product) The inkjet ink of the present invention is applied to the surface of a substrate by inkjet printing and then heated on a hot plate, oven, or the like, to obtain a polyimide film (cured film) as a cured product of the inkjet ink over the entire surface or in a predetermined pattern (e.g., line-like shape). The means for forming the cured film is not limited to heat treatment, and may also include UV treatment, treatment using an ion beam, an electron beam, or gamma rays, etc.

[0121] There are various types of inkjet ink application methods, depending on the ink ejection method. Examples of ejection methods include piezoelectric element type, bubble jet (registered trademark) type, continuous jet type, and electrostatic induction type. By appropriately selecting each component contained in the ink, the ink according to the present invention can be ejected in various ways, and the inkjet ink can be applied in a predetermined pattern.

[0122] The temperature for the heat treatment to cure the inkjet ink is typically about 100 to 350°C, and the substrate is set depending on the properties of the electronic product. A cured product can be obtained by heat treatment for 30 to 90 minutes when using an oven, or for 5 to 30 minutes when using a hot plate. When the inkjet ink film is formed in a pattern, a patterned cured product is formed. The cured film thus obtained has excellent etching resistance and alkali removability, making it useful as an etching resist material.

[0123] The inkjet ink of the present invention is a monomer composition with low viscosity, making it suitable for inkjet ejection, and has excellent viscosity stability at room temperature, making it easy to handle. Furthermore, since it exhibits good etching resistance and alkaline strippability over a wide temperature range of 120°C to 350°C, it can be used even in high-temperature processes. For example, it can be used as a highly acid-resistant etching resist for MEMS applications, which is in high demand in the market.

[0124] The present invention can also be implemented as a method for forming a cured film in the manufacture of electronic components. A resist film can be formed at a specific location by applying the inkjet ink of the present invention by an inkjet coating method, drying the ink, and then heating the film to form a cured film. This makes it possible to manufacture electronic components with complex package structures.

[0125] The present invention will be described in more detail below using examples, but the present invention is not limited to the examples specifically disclosed below. The names and abbreviations of the compounds used as components in the examples are shown below. These abbreviations will be used in the following description. In the compositions of the examples and comparative examples, the components other than KJCMPA (registered trademark)-100 used as a solvent and dehydrated DMAc are solid contents.

[0126] (Compounds used in synthesis of half ester (A)) PMDA: Pyromellitic anhydride manufactured by Tokyo Chemical Industry Co., Ltd. H-PMDA: PMDA-HS, 1R,2S,4S,5R-cyclohexanetetracarboxylic dianhydride manufactured by Iwatani Industrial Gases Corporation s-BPDA: 4,4'-biphthalic anhydride manufactured by Tokyo Chemical Industry Co., Ltd. H-s-BPDA: Dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride manufactured by Tokyo Chemical Industry Co., Ltd. ODPA: 4,4'-oxydiphthalic anhydride manufactured by Tokyo Chemical Industry Co., Ltd.

[0127] (Diamine (B)) HAB: 3,3'-dihydroxybenzidine manufactured by Tokyo Chemical Industry Co., Ltd. BAS: bis(3-amino-4-hydroxyphenyl)sulfone manufactured by Tokyo Chemical Industry Co., Ltd. 6FAP: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane manufactured by Tokyo Chemical Industry Co., Ltd. BHAPP: 2,2-bis(3-amino-4-hydroxyphenyl)propane manufactured by Tokyo Chemical Industry Co., Ltd. 2,2'-DCB: 4,4'-diamino-[1,1'-biphenyl]-2,2'-dicarboxylic acid manufactured by Ambeeed DABzA: 3,5-diaminobenzoic acid manufactured by Tokyo Chemical Industry Co., Ltd. BAPBA: 3,5-bis(4-aminophenoxy)benzoic acid manufactured by Tokyo Chemical Industry Co., Ltd. MBAA: manufactured by Seika Corporation 5,5'-methylenebis(2-aminobenzoic acid) O-dianisidine: manufactured by Tokyo Chemical Industry Co., Ltd. O-tolidine: manufactured by Tokyo Chemical Industry Co., Ltd. DDS: manufactured by Tokyo Chemical Industry Co., Ltd. Bis(4-aminophenyl)sulfone

[0128] (Solvent) KJCMPA (registered trademark)-100: 3-methoxy-N,N-dimethylpropanamide manufactured by KJ Chemicals Co., Ltd. Dehydrated DMAc: N,N-dimethylacetamide (super dehydrated) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Dehydrated methanol: Methanol (super dehydrated) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Dehydrated ethanol: Ethanol (super dehydrated) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (Surfactant) KP-341 (product name): Polyether type surface modifier manufactured by Shin-Etsu Chemical Co., Ltd. (Stripping liquid) Phosphoric acid: HF50% manufactured by Tokyo Chemical Industry Co., Ltd. Hydrofluoric acid: Semiconductor-grade hydrofluoric acid manufactured by Daikin Industries, Ltd. TMAH: Tetramethylammonium hydroxide (approximately 25% aqueous solution) manufactured by Tokyo Chemical Industry Co., Ltd.

[0129] (Device name) FT-IR: FT-IR 6700V manufactured by JASCO Corporation E-type rotational viscometer: VISCOMETER TV-22, TV-100E manufactured by Toki Sangyo Co., Ltd. GPC: LC-2000 series manufactured by JASCO Corporation

[0130] (Measurement conditions) Column: Shodex GF-510HQ, GF-310HQ (two columns in series) manufactured by Resonac Corporation Mobile phase: DMF (containing 0.63% phosphoric acid) Flow rate: 1.0 ml / min Temperature: 40°C Detector: RI Molecular weight standard sample: polystyrene resin with known molecular weight

[0131] (Synthesis of Half Ester (A)) (Synthesis Example 1) Synthesis of PMDA-ME 50.0 g of PMDA, 130.7 g of KJCMPA (registered trademark)-100, and 18.4 g of dehydrated methanol were placed in a 300 mL three-neck flask equipped with a thermometer, a stirrer, a raw material charging port, and a nitrogen gas inlet, and the mixture was stirred at 70° C. for 3 hours. FT-IR showed peaks of 1770 and 1850 cm attributed to the acid anhydride group. -1 After confirming that the peak in the vicinity had disappeared, heating was stopped to obtain a KJCMPA-100 solution of PMDA-ME (solid content 32.5%).

[0132] Synthesis Example 2 Synthesis of H-PMDA-ME 8.0 g of H-PMDA, 23.4 g of dehydrated DMAc, and 2.3 g of dehydrated methanol were placed in a 100 mL three-neck flask equipped with a thermometer, a stirrer, a raw material inlet, and a nitrogen gas inlet, and the mixture was stirred at 70° C. for 3 hours. -1 After confirming that the peak had disappeared, heating was stopped to obtain a DMAc solution of H-PMDA-ME (solid content 30.0%).

[0133] Synthesis Example 3 Synthesis of s-BPDA-ME 20.0 g of s-BPDA, 43.1 g of KJCMPA (registered trademark)-100, and 6.4 g of dehydrated methanol were placed in a 100 mL three-neck flask equipped with a thermometer, a stirrer, a raw material charging port, and a nitrogen gas inlet, and the mixture was stirred at 80° C. for 6 hours. FT-IR showed peaks of 1770 and 1850 cm attributed to the acid anhydride group. -1 After confirming that the peak in the vicinity had disappeared, heating was stopped to obtain a solution of s-BPDA-ME in KJCMPA-100 (solid content 35.0%).

[0134] Synthesis Example 4 Synthesis of H-s-BPDA-ME 5.0 g of H-s-BPDA, 16.8 g of KJCMPA (registered trademark)-100, 6.5 g of dehydrated DMAc, and 1.8 g of dehydrated methanol were placed in a 50 mL three-neck flask equipped with a thermometer, a stirrer, a raw material charging port, and a nitrogen gas inlet, and the mixture was stirred for 5 hours at 75° C. After confirming that the peaks at around 1770 and 1850 cm attributed to the acid anhydride group had disappeared in FT-IR, heating was stopped, and a mixed solution of H-s-BPDA-ME in KJCMPA-100 and DMAc (solids content 20.1%) was obtained.

[0135] Synthesis Example 5 Synthesis of ODPA-ME 40.0 g of ODPA, 41.2 g of KJCMPA (registered trademark)-100, and 10.3 g of dehydrated methanol were placed in a 300 mL three-neck flask equipped with a thermometer, a stirrer, a raw material charging port, and a nitrogen gas inlet, and the mixture was stirred at 80° C. for 7 hours and then at room temperature for 16 hours. -1 It was confirmed that the peak around this point had disappeared, and a solution of ODPA-ME in KJCMPA-100 (solid content: 50.4%) was obtained.

[0136] Synthesis Example 6 Synthesis of PMDA-EE Into a 200 mL three-neck flask equipped with a thermometer, a stirrer, a raw material inlet, and a nitrogen gas inlet, 40.0 g of PMDA, 56.9 g of KJCMPA (registered trademark)-100, and 21.1 g of dehydrated ethanol were placed and stirred at 70° C. for 5 hours. FT-IR showed peaks of 1770 and 1850 cm attributed to acid anhydride groups. -1 After confirming that the peak in the vicinity had disappeared, heating was stopped to obtain a KJCMPA-100 solution of PMDA-EE (solid content 47.6%).

[0137] The chemical formulas and abbreviations of the half esters (A) and diamines (B) used in preparing the inkjet inks in the present examples and comparative examples are shown below. In the following structural formulas, Me represents methyl and Et represents ethyl.

[0138]

[0139] (Ink Preparation) (Preparation Example 1) 149.8 g of a solution of HAB in KJCMPA-100 (solid content 13.3%) was mixed and stirred with 80.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 1.

[0140] Preparation Example 2 11.8 g of a DMAc solution of HAB (solid content 13.3%) was mixed with 7.0 g of a DMAc solution of H-PMDA-ME (solid content 30.0%) obtained in Synthesis Example 2 and stirred, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 2.

[0141] Preparation Example 3 23.8 g of a solution of HAB in KJCMPA-100 (solid content 13.3%) was mixed and stirred with 15.0 g of a solution of s-BPDA-ME in KJCMPA-100 (solid content 35.0%) obtained in Synthesis Example 3, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 3.

[0142] Preparation Example 4 1.8 g of a DMAc solution of HAB (solid content 13.3%) was mixed with 2.0 g of a KJCMPA-100 / DMAc mixed solution of H-s-BPDA-ME obtained in Synthesis Example 4 (solid content 20.1%) and stirred, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 4.

[0143] Preparation Example 5 8.7 g of a solution of HAB in KJCMPA-100 (solid content 10.0%) was mixed and stirred with 3.0 g of a solution of ODPA-ME in KJCMPA-100 (solid content 50.4%) obtained in Synthesis Example 5, and 1500 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 5.

[0144] Preparation Example 6 123.9 g of a solution of HAB in KJCMPA-100 (solid content 11.7%) was mixed and stirred with 52.0 g of the solution of PMDA-EE in KJCMPA-100 (diluted to a solid content of 40.0%) obtained in Synthesis Example 6, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 6.

[0145] Preparation Example 7 10.4 g of a solution of BAS in KJCMPA-100 (solid content 14.0%) was mixed and stirred with 4.5 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 7.

[0146] Preparation Example 8 3.9 g of a solution of 6FAP in KJCMPA-100 (solid content 14.0%) was mixed with 1.3 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 8.

[0147] Preparation Example 9 3.2 g of a solution of BHAPP in KJCMPA-100 (solid content 13.8%) was mixed with 1.5 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 9.

[0148] Preparation Example 10 2.6 g of a DMAc solution of 2,2′-DCB (solid content 10.0%) was mixed with 1.5 g of a KJCMPA-100 solution of PMDA-ME obtained in Synthesis Example 1 (solid content 32.5%) and stirred, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 10.

[0149] Preparation Example 11 8.4 g of a solution of DABzA in KJCMPA-100 (solid content 11.5%) was mixed with 5.5 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 11.

[0150] Preparation Example 12 5.9 g of a solution of HAB in KJCMPA-100 (solid content 13.3%) was mixed with 3.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 12.

[0151] Preparation Example 13 2.8 g of a solution of HAB in KJCMPA-100 (solid content 13.3%) was mixed with 1.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 13.

[0152] Preparation Example 14 5.3 g of a solution of HAB in KJCMPA-100 (solid content 13.3%) was mixed and stirred with 3.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 14.

[0153] Preparation Example 15 1.8 g of a solution of HAB in KJCMPA-100 (solid content 13.3%) was mixed and stirred with 1.5 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 15.

[0154] Preparation Example 16 2.5 g of a solution of HAB in KJCMPA-100 (solid content 10.0%) was mixed and stirred with 2.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 16.

[0155] Preparation Example 17 4.4 g of a solution of BAPBA in KJCMPA-100 (solid content 13.2%) was mixed with 1.5 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 17.

[0156] Preparation Example 18 4.6 g of a solution of BAPBA in KJCMPA-100 (solid content 13.0%) was mixed with 1.7 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 18.

[0157] Preparation Example 19 4.6 g of a solution of BAPBA in KJCMPA-100 (solid content 12.2%) was mixed with 1.9 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 19.

[0158] Preparation Example 20 5.3 g of a solution of BAPBA in KJCMPA-100 (solid content 11.7%) was mixed and stirred with 2.4 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 20.

[0159] Preparation Example 21 3.8 g of a solution of MBAA in KJCMPA-100 (solid content 13.2%) was mixed and stirred with 1.5 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 21.

[0160] Preparation Example 22 3.9 g of a solution of MBAA in KJCMPA-100 (solid content 13.0%) was mixed and stirred with 1.7 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 22.

[0161] Preparation Example 23 4.0 g of a solution of MBAA in KJCMPA-100 (solid content 12.2%) was mixed with 1.9 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 23.

[0162] Preparation Example 24 4.5 g of a solution of MBAA in KJCMPA-100 (solid content 11.7%) was mixed and stirred with 2.4 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 24.

[0163] Preparation Example 25 6.1 g of a solution of O-dianisidine in KJCMPA-100 (solid content 13.8%) was mixed with 3.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 25.

[0164] Preparation Example 26 9.2 g of a solution of O-tolidine in KJCMPA-100 (solid content 13.3%) was mixed with 5.0 g of a solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1 and stirred, and 1000 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 26.

[0165] Preparation Example 27 3.6 g of a solution of DDS in KJCMPA-100 (solid content 12.0%) was mixed and stirred with 1.5 g of the solution of PMDA-ME in KJCMPA-100 (solid content 32.5%) obtained in Synthesis Example 1, and 150 ppm of KP-341 (product name) was added as a surfactant to obtain Ink 27.

[0166] (Etching Resistance / Alkali Strippability Test) (Examples 1 to 16, 19 to 26) Each of Inks 1 to 24 prepared in Preparation Examples 1 to 24 was spin-coated onto a silicon wafer cut to a size of 2 × 2.5 cm at 700 rpm for 10 seconds and 1000 rpm for 5 seconds, dried at 80°C for 5 minutes, and heated at each temperature shown in Tables 1 to 4 from 100 to 350°C for 30 minutes to obtain a silicon wafer with a cured film having a film thickness of 1 to 3 μm.

[0167] An etching resistance test was carried out on these test pieces under the following conditions (condition 1), and test pieces that passed the test were further subjected to an alkali strippability test.

[0168] (Etching resistance test: condition 1) A test piece of a silicon wafer with a cured film was immersed in 89% phosphoric acid for 30 minutes, washed twice with pure water, and then the state of the film was visually confirmed. If the film on the substrate was not peeled off, it was judged as ◯ (pass), and if it was peeled off, it was judged as × (fail).

[0169] (Alkali Stripping Test) A test piece was immersed in a 2.38% TMAH aqueous solution for 15 minutes, washed twice with pure water, and then the state of the film was visually confirmed. If the film on the substrate was completely dissolved or peeled off, it was judged as ◯ (pass), and if the film remained, it was judged as × (fail). Note that for specimens for which the etching resistance test was × (fail) and therefore the alkali stripping test was not performed, a "-" is added to the evaluation result column in Tables 1 to 4.

[0170] (Examples 17 and 18) Inks 1 and 6 prepared in Preparation Examples 1 and 6 were spin-coated onto silicon wafers cut to a size of 2 x 2.5 cm at 700 rpm for 10 seconds and 1000 rpm for 5 seconds, dried at 80°C for 5 minutes, and heated at temperatures ranging from 100 to 350°C as shown in Table 3 for 30 minutes to obtain silicon wafers with cured films having thicknesses of 1 to 3 μm. (Etching Resistance Test: Condition 2) For these test pieces, an etching resistance test was conducted in the same manner as in Example 1, except that a mixed solution of 4% hydrofluoric acid and 82% phosphoric acid was used instead of the 89% phosphoric acid used in Condition 1 above, and the results were evaluated based on the same criteria as in Condition 1. (Alkali Stripping Test) The etching resistance test was conducted under Condition 2, and test pieces that passed were further subjected to an alkali stripping test.

[0171] Comparative Examples 1 to 3 Inks 25 to 27 prepared in Preparation Examples 25 to 27 were each spin-coated onto a silicon wafer cut to a size of 2 x 2.5 cm at 700 rpm for 10 seconds and 1,000 rpm for 5 seconds, dried at 80°C for 5 minutes, and heated at 100 to 350°C for 30 minutes to obtain silicon wafers with cured films having thicknesses of 1 to 3 μm. Etching resistance tests were performed on these test pieces under the same conditions as in Example 1.

[0172] 4 is a photograph showing the results of evaluating a silicon wafer with a cured film formed by heating the inkjet ink of Example 1, which contains PMDA-ME as the half ester (A), HAB as the diamine (B), and KJCMPA-100 as the solvent (C). As shown in the figure, the silicon wafer with a cured film heated to a temperature of 120°C partially dissolved after immersion in phosphoric acid. The silicon wafer with a cured film heated to a temperature of 150 to 300°C remained unchanged after immersion in phosphoric acid compared to before immersion, and thus had sufficient etching resistance.

[0173] Of the silicon wafers with cured films that had sufficient etching resistance, those heated to temperatures of 250° C. and 300° C. left some undissolved film after immersion in TMAH, but those heated to temperatures of 150 to 230° C. completely dissolved the cured film after immersion in TMAH. In other words, the inkjet ink of Example 1 yielded a cured film that exhibited good etching resistance and alkali solubility at heating temperatures of 150 to 230° C.

[0174] The etching resistance and alkali strippability of the silicon wafers with cured films produced using the inkjet inks of Examples 2 to 26 and Comparative Examples 1 to 3 were evaluated in the same manner as in Example 1, and the results are shown in Tables 1 to 4 below.

[0175] As shown in Tables 1 and 2, by using half ester (A), diamine (B), and solvent (C), it was possible to prepare silicon wafers with cured films that exhibited good etching resistance and alkaline strippability over a wide temperature range, from low to high. In Comparative Examples 1 to 3, in which diamine (B) having neither a phenolic hydroxyl group nor a carboxylic acid group was used, silicon wafers with cured films that exhibited good etching resistance and alkaline strippability could not be obtained by using it in combination with half ester (A). From these results, it can be said that diamine (B) used in combination with half ester (A) preferably has at least one phenolic hydroxyl group and / or carboxylic acid group.

[0176]

[0177]

[0178] The results in Tables 3 and 4 indicate that the cured inkjet ink exhibits good etching resistance and alkali removability when the molar ratio of half ester (A):diamine (B) is in the range of 1:0.5 or greater and 1:2 or less. Furthermore, as the proportion of diamine (B) in the inkjet ink increases, the heating temperature required to form a cured film exhibiting good etching resistance decreases, and alkali removability tends to decrease when the cured film is formed at a high temperature. Example 14 produced cured films exhibiting good etching resistance and alkali removability over a wide range of heating temperatures: 150°C to 300°C, Example 15 produced cured films from 200°C to 350°C, and Examples 16 and 26 produced cured films from 230°C to 350°C. Based on these results, a molar ratio of half ester (A):diamine (B) of 1:0.50 to 1:0.97 is preferred from the standpoint of compatibility with a wide range of temperatures.

[0179] (Storage Stability Test) The sample was stored in a dry box at 25° C., and the viscosity was measured after 0, 7, 14 and 30 days using an E-type rotational viscometer to track the change.

[0180] Synthesis Example 7 Synthesis of Polyamic Acid 1 (PMDA / HAB Polyamic Acid) 5.0 g of HAB, 5.0 g of PMDA, and 89.6 g of KJCMPA-100 were added to a 100 mL three-neck flask equipped with a thermometer, a stirrer, a raw material inlet, and a nitrogen gas inlet, and the mixture was stirred at room temperature for 3 hours to obtain Polyamic Acid 1 (solids concentration: 10%) having the following structure. The weight average molecular weight (Mw) measured by GPC was 150,000, and the polydispersity index was 2.8. The viscosity measured using an E-type rotational viscometer was 32.3 Pa s.

[0181]

[0182] Example 27 Ink 1 prepared in the same manner as in Preparation Example 1 was placed in a glass screw tube and stored in a dry box at 25°C. The viscosity was measured after 0, 7, 14 and 30 days using an E-type rotational viscometer to track any changes.

[0183] Example 28 Ink 6 prepared in the same manner as in Preparation Example 6 was placed in a glass screw tube and stored in a dry box at 25°C. The viscosity was measured after 0, 7, 14 and 30 days using an E-type rotational viscometer to track the changes.

[0184] Comparative Example 4 Polyamic acid 1 synthesized in Synthesis Example 7 was placed in a glass screw tube, and the viscosity was monitored in the same manner as in Example 19.

[0185] The viscosity changes of Examples 27 and 28 and Comparative Example 4 are shown in Table 5 below and FIG. As shown in Table 5, ink 1 of Example 27 and ink 6 of Example 28, in which half ester (A) and diamine (B) were dissolved in solvent (C), both had lower viscosity and could have higher solids concentrations than the solution of polyamic acid 1 of Comparative Example 4, making them suitable as inkjet inks. Furthermore, the viscosity change when left at room temperature (25°C) after preparation was small, making them easy to handle during production, supply, and distribution, and they were inkjet inks with excellent room temperature stability that could be stably produced.

[0186] The ink-jet ink of the present invention is used, for example, in the manufacture of electronic components having complex package structures, such as MEMS (Micro Electro Mechanical Systems).

[0187] 1: Substrate 2: Film to be processed 3: Resist 4: Mask

Claims

1. An inkjet ink comprising a half ester (A), a diamine (B), and a solvent (C).

2. The ink-jet ink according to claim 1, wherein the molar ratio of said half ester (A): said diamine (B) is 1:0.5 or more and 1:2 or less.

3. The ink-jet ink according to claim 1, wherein the half ester (A) is represented by formula (1a) or (1b). (R in formula (1a) and formula (1b) 1 is an organic group having an aliphatic hydrocarbon structure and 2 to 100 carbon atoms, or an organic group having an unsaturated hydrocarbon structure and 2 to 100 carbon atoms, 2 are independently alkyl having 1 to 30 carbon atoms or phenyl in which at least one hydrogen may be replaced by -F, -CH3, -OCH3, -OCH2F, -OCHF2, or -OCF3, and in the alkyl having 1 to 30 carbon atoms and alkyl having 1 to 10 carbon atoms, at least one -CH2- may be replaced by -CF2-, -CHF-, -O-, -CH=CH-, or -C≡C-, and at least one -CH3 may be replaced by -CH2F, -CHF2, or -CF3.

4. The ink-jet ink according to claim 1, wherein the half ester (A) is represented by formula (1a) or (1b). (R in formula (1a) and formula (1b) 1 is an organic group having one or two benzene rings or an organic group having one or two cyclohexane rings, R 2 are independently methyl or ethyl.

5. The ink-jet ink according to claim 1, wherein the diamine (B) is represented by formula (2). (R in formula (2) 3 is an organic group having an unsaturated hydrocarbon structure and having 2 to 100 carbon atoms.

6. The ink-jet ink according to claim 1, wherein the diamine (B) is represented by formula (2). (R in formula (2) 3 is an organic group having one, two or three benzene rings.

7. The ink-jet ink according to claim 1, wherein the diamine (B) has one or more phenolic hydroxyl groups and / or carboxylic acid groups.

8. The ink-jet ink according to claim 1, wherein the half ester (A) is a half ester obtained by reacting at least one member selected from the group consisting of pyromellitic anhydride (PMDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA), 4,4'-biphthalic anhydride (s-BPDA), 3,4'-biphthalic anhydride (a-BPDA), 4,4'-oxydiphthalic anhydride (ODPA), and dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (HBPDA) with an alcohol.

9. The ink-jet ink according to claim 1, wherein the diamine (B) is at least one selected from the group consisting of 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, bis(3-amino-4-hydroxyphenyl)sulfone, 4,4'-diaminobiphenyl-2,2'-dicarboxylic acid, 5,5'-methylenebis(2-aminobenzoic acid), 3,5-bis(4-aminophenoxy)benzoic acid, and 3,5-diaminobenzoic acid.

10. A cured product obtained by heating the inkjet ink according to any one of claims 1 to 9.

11. A method for forming a cured film, comprising the steps of applying the inkjet ink according to any one of claims 1 to 9 by an inkjet application method, and then drying the applied ink to form a film, and heating the film to form a cured film.

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