Polyimide resin, polyimide varnish, polyimide film, and temporary fixing material composition

Abstract

A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A includes a structural unit (A1) derived from a compound represented by formula (a1), and the structural unit B includes a structural unit (B1) derived from a compound represented by formula (b1) and a structural unit (B2) derived from a compound represented by formula (b2) (Z is a diphenylfluorene structure or a hexafluoro diphenylpropane structure, and X1 and X2 each represent -O-, -C(CH3)2-, or -C(CF3)2-.).

Description

Polyimide resin, polyimide varnish, polyimide film, and temporary fixing material composition

[0001] The present invention relates to a polyimide resin, a polyimide varnish, a polyimide film, and a temporary fixing material composition.

[0002] In recent years, semiconductor electronic components have become lighter and thinner. In 2.5-dimensional and 3-dimensional semiconductor packaging, technological developments are underway to thin semiconductor chips and stack them in multiple layers while connecting them via through-silicon vias (TSVs) to achieve higher integration and higher density of semiconductor elements. Furthermore, in the field of power semiconductors, efforts are being made to thin semiconductor electronic circuit boards to reduce conduction loss for energy conservation. One method for thinning semiconductor electronic circuit boards is, for example, grinding the non-circuit-forming surface (backside) of the semiconductor electronic circuit board. Conventionally, during the grinding process, backgrinding tape (protective tape) is applied to the side opposite the grinding surface to prevent damage during grinding. However, backgrinding tape has insufficient heat resistance and is not suitable for the high-temperature processes used in the TSV and power semiconductor fields. Therefore, a method has been proposed in which a semiconductor electronic circuit-forming substrate is fixed to a support substrate such as a supportable silicon wafer or glass substrate via a temporary fixing material (adhesive layer), and then the processed semiconductor circuit-forming substrate is peeled off from the support substrate after grinding, backside circuit formation processing, etc. This temporary fixing material is required to have heat resistance, peelability, low-temperature drying, and low-temperature adhesion properties sufficient to withstand the manufacturing process of semiconductor electronic components.

[0003] As a method for separating a semiconductor electronic circuit forming substrate from a supporting substrate, a method of dissolving the temporary fixing material in a solvent and separating the substrate from the supporting substrate (see, for example, Patent Document 1) and a method of irradiating the temporary fixing material with a laser from the supporting substrate side have been proposed. In addition, a polyimide-based material has been proposed as a temporary fixing material with excellent heat resistance (see, for example, Patent Document 2).

[0004] JP 2011-233679 A JP 2010-254808 A

[0005] In the field of power semiconductors, heat resistance of 350°C or higher is required during the annealing process and backmetal process after ion implantation. On the other hand, to reduce process energy consumption and improve productivity, it is preferable to be able to dry and bond the temporary fixing material at lower temperatures when forming the film. Furthermore, easy peeling is also required after the heat treatment process is completed. When removing a polyimide-based temporary fixing material using a solvent, a polar solvent is preferred. However, due to concerns about reduced solubility due to solvent moisture absorption, it is necessary to dissolve the polyimide in a polar solvent with low water absorption, such as γ-butyrolactone or cyclopentanone. Thus, easy solubility in solvents with various properties is required. When removing a polyimide-based temporary fixing material using laser irradiation, the polyimide-based temporary fixing material is required to have excellent light absorption properties at a wavelength of 355 nm, particularly to be compatible with a 355 nm UV solid-state laser. As described above, there is a need for a temporary fixing material that can bond a semiconductor electronic circuit forming substrate and a support substrate at low temperatures, that can be passed through a semiconductor electronic component manufacturing process that involves heat treatment at 350°C or higher, and that can be peeled off with various solvents and laser. Therefore, an object of the present invention is to provide a polyimide resin, a polyimide film, a polyimide varnish containing the polyimide resin, and a temporary fixing material composition containing the polyimide resin, that have a low elastic modulus, a low glass transition temperature, and heat resistance, and that have excellent solvent solubility and low light transmittance at a wavelength of 355 nm.

[0006] The present inventors have discovered that a polyimide resin containing a combination of structural units derived from a specific tetracarboxylic dianhydride and structural units derived from a specific diamine can solve the above problems, and have thus completed the present invention.

[0007] That is, the present invention relates to the following items <1> to <10>: <1> A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, wherein the structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1), and the structural unit B includes a structural unit (B1) derived from a compound represented by the following formula (b1): (In the formula, Z is a group represented by the following formula (1) or a group represented by the following formula (2). X 1 and X 2 each independently represents —O—, —C(CH3)2—, or —C(CF3)2—. (In formula (2), R 1 and R 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms.) <2> The polyimide resin according to the above <1>, wherein the proportion of the structural unit (A1) within the structural unit A is 30 to 100 mol %. <3> The polyimide resin according to the above <1> or <2>, wherein the proportion of the structural unit (B1) within the structural unit B is 30 to 100 mol %. <4> The polyimide resin according to any one of the above <1> to <3>, wherein the structural unit (A1) includes at least one selected from the group consisting of a structural unit (A11) derived from a compound represented by the following formula (a11) and a structural unit (A12) derived from a compound represented by the following formula (a12): <5> The polyimide resin according to any one of the above <1> to <4>, in which the structural unit (B1) includes a structural unit (B11) derived from a compound represented by the following formula (b11): <6> The polyimide resin according to any one of the above <1> to <5>, in which the structural unit B further contains a structural unit (B2) derived from a compound represented by the following formula (b2): (In the formula, X 3 and X 4 each independently represents —O—, —COO—, or —OCO—, and n is an integer of 2 to 10.) <7> The polyimide resin according to any one of the above <1> to <6>, which contains a structural unit represented by the following general formula (3): (In the formula, L 1 and L 2are each independently a monovalent aliphatic hydrocarbon having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, and m is an integer of 1 to 200. <8> A polyimide varnish containing the polyimide resin according to any one of <1> to <7> above and an organic solvent. <9> A polyimide film containing the polyimide resin according to any one of <1> to <7> above. <10> A temporary fixing material composition containing the polyimide resin according to any one of <1> to <7> above.

[0008] According to the present invention, it is possible to provide a polyimide resin that has a low elastic modulus, a low glass transition temperature, and heat resistance, excellent solvent solubility, and a low light transmittance at a wavelength of 355 nm; a polyimide film; a polyimide varnish containing the polyimide resin; and a temporary fixing material composition containing the polyimide resin.

[0009] [Polyimide Resin] The polyimide resin of the present invention is a polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, in which the structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1), and the structural unit B includes a structural unit (B1) derived from a compound represented by the following formula (b1): (In the formula, Z is a group represented by the following formula (1) or a group represented by the following formula (2). X 1 and X 2 each independently represents —O—, —C(CH3)2—, or —C(CF3)2—. (In formula (2), R 1 and R 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms.

[0010] The reasons why the polyimide resin of the present invention has a low elastic modulus, a low glass transition temperature, and heat resistance, excellent solvent solubility, and a low light transmittance at a wavelength of 355 nm are not clear, but are thought to be as follows: It is believed that the polyimide resin contains structural units derived from a specific tetracarboxylic dianhydride having an ether skeleton and a bulky skeleton (a trifluoromethyl group or a cardo skeleton), and has structural units derived from a nonlinear aromatic diamine, thereby achieving the seemingly contradictory properties of heat resistance (high weight loss temperature) and a low glass transition temperature, and further having solubility in solvents and light absorption at a specific wavelength.

[0011] <Structural Unit A> The structural unit A is a structural unit derived from a tetracarboxylic dianhydride contained in a polyimide resin. The structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1). (In the formula, Z is a group represented by the following formula (1) or a group represented by the following formula (2).) (In formula (2), R 1 and R 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms.) By including the structural unit (A1) in the structural unit A, the heat resistance of the polyimide resin can be improved while the glass transition temperature can be lowered. In addition, the solvent solubility and light absorbance at a wavelength of 355 nm can be improved.

[0012] The compound represented by formula (a1) preferably includes at least one selected from the group consisting of compounds represented by formula (a11) and compounds represented by formula (a12) below, and more preferably at least one selected from the group consisting of compounds represented by formula (a11) and compounds represented by formula (a12) below. From the viewpoint of solvent solubility in particular, the compound represented by formula (a11) below is preferred, and from the viewpoint of light absorbance at a wavelength of 355 nm, the compound represented by formula (a12) below is preferred. That is, the structural unit (A1) preferably includes at least one selected from the group consisting of structural units (A11) derived from compounds represented by formula (a11) below and structural units (A12) derived from compounds represented by formula (a12) below, and more preferably at least one selected from the group consisting of structural units (A11) derived from compounds represented by formula (a11) below and structural units (A12) derived from compounds represented by formula (a12) below. In particular, from the viewpoint of solvent solubility, the structural unit (A11) derived from a compound represented by the following formula (a11) is preferred, and from the viewpoint of light absorbance at a wavelength of 355 nm, the structural unit (A12) derived from a compound represented by the following formula (a12) is preferred.

[0013] The compound represented by formula (a11) is 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride (6F-BPADA). When structural unit A contains structural unit (A11), the heat resistance of the polyimide resin can be improved while the glass transition temperature can be lowered. In addition, the solvent solubility and light absorbency at a wavelength of 355 nm can be improved. The compound represented by formula (a12) is 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (BPF-PA). When structural unit A contains structural unit (A12), the heat resistance of the polyimide resin can be improved while the glass transition temperature can be lowered. In addition, the solvent solubility and light absorbency at a wavelength of 355 nm can be improved. From the viewpoint of achieving both a low glass transition temperature and heat resistance, the structural unit (A1) preferably includes the structural unit (A11), and the structural unit (A1) is more preferably the structural unit (A11).

[0014] The structural unit A may be composed only of the structural unit (A1), or may include a structural unit other than the structural unit (A1). Preferably, however, the structural unit A further includes a structural unit (A2) derived from a compound represented by the following formula (a2) as a structural unit other than the structural unit (A1): (In the formula, L 3 , L 4 , L 5 and L 6 are each independently a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms; Z 1 and Z 2 each independently represents a trivalent aliphatic group or a trivalent aromatic group, and m is an integer of 1 to 200.

[0015] In formula (a2), Z 1 and Z 2The trivalent aliphatic group or trivalent aromatic group in the formula (I) may be substituted with a fluorine atom or may contain an oxygen atom. When an oxygen atom is contained as an ether bond, the carbon number shown below refers to the total number of carbon atoms contained in the aliphatic group or aromatic group. Examples of the trivalent aliphatic group include trivalent saturated or unsaturated aliphatic groups having 1 to 20 carbon atoms. The trivalent aliphatic group preferably has 4 to 20 carbon atoms. Examples of the trivalent saturated aliphatic group include groups in which an alkylene group having 1 to 19 carbon atoms is bonded to a methylidyne group, and groups in which 1 to 3 groups selected from the group consisting of alkyleneoxy groups having 1 to 19 carbon atoms are bonded to the methylidyne group. Examples of alkylene groups include methylene, ethylene, propylene, trimethylene, tetramethylene, hexamethylene, octamethylene, decamethylene, and dodecamethylene groups. Examples of alkyleneoxy groups include propyleneoxy and trimethyleneoxy groups. Examples of trivalent unsaturated aliphatic groups include groups in which at least one alkenylene group having 2 to 19 carbon atoms is bonded to a methylidyne group. Furthermore, an alkylene group or alkyleneoxy group may be bonded to the methylidyne group. Examples of alkenylene groups include vinylene and propenylene groups. Examples of trivalent aromatic groups include arylidine groups having 6 to 20 carbon atoms, and groups in which one to three groups selected from the group consisting of arylene groups having 6 to 20 carbon atoms and aralkylene groups having 7 to 20 carbon atoms are bonded to a methylidyne group. Specific examples of the arylene group include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 4,4'-biphenylylene group, and a 2,6-naphthylene group. 1 and Z 2 As the alkyl group, a group in which a trimethylene group and a methylene group are bonded to a methylidyne group, and a group in which a p-phenylene group and a methylene group are bonded to a methylidyne group are particularly preferred, and a group in which a trimethylene group and a methylene group are bonded to a methylidyne group is more preferred.

[0016] In formula (a2), L 3 ~L 6In formula (a2), examples of the monovalent aliphatic hydrocarbon having 1 to 5 carbon atoms include monovalent saturated or unsaturated aliphatic groups. Examples of the monovalent saturated aliphatic group include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, and propyl groups. A methyl group is preferred as the monovalent saturated aliphatic group. Examples of the monovalent unsaturated aliphatic group include alkenyl groups having 2 to 5 carbon atoms, such as vinyl and propenyl groups. These groups may be substituted with a fluorine atom. L in formula (a2) 3 ~L 6 Examples of the monovalent aromatic group having 6 to 10 carbon atoms in L include an aryl group having 6 to 10 carbon atoms, an aryl group substituted with an alkyl group having 7 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms. As the monovalent aromatic group, an aryl group is preferred, and a phenyl group is more preferred. 3 , L 4 , L 5 and L 6 is preferably at least one selected from the group consisting of a monovalent saturated aliphatic group and a monovalent aromatic group, more preferably at least one selected from the group consisting of a methyl group and a phenyl group, and even more preferably a methyl group. In formula (a2), m is an integer of 1 to 200, preferably an integer of 10 to 100.

[0017] As described above, among the compounds represented by the above formula (a2), the compound represented by the following formula (a21) is preferred.

[0018] (In formula (a21), L 31 and L 41 are each independently a methyl group or a phenyl group, and m has the same definition as m in formula (a2), and the preferred range is also the same.

[0019] In formula (a21), m is an integer of 1 to 200, preferably an integer of 10 to 100. 31 and L 41 are each independently a methyl group or a phenyl group, and preferably a methyl group. 31 The silicon atom to which the methyl group is bonded has L 41 Preferably, a methyl group is bonded as L 31The silicon atom to which the phenyl group is bonded has L 41 Preferably, a phenyl group is bonded as the functional group equivalent of the compound represented by formula (a2). The functional group equivalent of the compound represented by formula (a2) is preferably 50 to 3,000 g / mol, more preferably 100 to 1,000 g / mol, and even more preferably 150 to 700 g / mol. The functional group equivalent means the mass of the compound represented by formula (a2) per mole of the functional group (carboxy group).

[0020] Among the compounds represented by the above general formula (a2), examples of commercially available products include the "X-22-168" series manufactured by Shin-Etsu Chemical Co., Ltd.

[0021] By including the structural unit (A2), the structural unit A can have a low modulus of elasticity, and can achieve both a low glass transition temperature and heat resistance.

[0022] The molar ratio of the structural unit (A1) to the structural unit (A2) in the structural unit A [(A1) / (A2)] is preferably 70 / 30 to 100 / 0, more preferably 80 / 20 to 100 / 0, even more preferably 85 / 15 to 100 / 0, even more preferably 85 / 15 to 99 / 1, even more preferably 85 / 15 to 97 / 3, and even more preferably 85 / 15 to 95 / 5. When the molar ratio of the structural unit (A1) to the structural unit (A2) is 100 / 0, the structural unit A does not contain the structural unit (A2). By achieving this molar ratio, the elastic modulus can be reduced, and both a low glass transition temperature and heat resistance can be achieved.

[0023] The proportion of the structural unit (A1) in the structural unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and from the viewpoint of heat resistance and solvent solubility, even more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and preferably 100 mol% or less. The structural unit A may consist solely of the structural unit (A1). The proportion of the structural unit (A2) in the structural unit A is preferably 0 to 30 mol%, more preferably 0 to 20 mol%, even more preferably 0 to 15 mol%, even more preferably 1 to 15 mol%, even more preferably 3 to 15 mol%, and even more preferably 5 to 15 mol%. The total proportion of the structural unit (A1) and the structural unit (A2) in the structural unit A is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. The structural unit A may be composed only of the structural unit (A1) and the structural unit (A2).

[0024] The structural unit A may contain a structural unit other than the structural unit (A1) and the structural unit (A2). The tetracarboxylic acid dianhydride that provides such a structural unit is not particularly limited, and examples include aromatic tetracarboxylic acid dianhydrides excluding compounds represented by formula (a1), alicyclic tetracarboxylic acid dianhydrides, and aliphatic tetracarboxylic acid dianhydrides. In this specification, the term "aromatic tetracarboxylic acid dianhydride" refers to a tetracarboxylic acid dianhydride containing one or more aromatic rings, the term "alicyclic tetracarboxylic acid dianhydride" refers to a tetracarboxylic acid dianhydride containing one or more alicyclic rings but no aromatic rings, and the term "aliphatic tetracarboxylic acid dianhydride" refers to a tetracarboxylic acid dianhydride containing neither an aromatic ring nor an alicyclic ring. The structural unit optionally contained in the structural unit A may be one type, or two or more types.

[0025] <Structural Unit B> The structural unit B is a structural unit derived from a diamine contained in a polyimide resin. The structural unit B includes a structural unit (B1) derived from a compound represented by the following formula (b1). (In the formula, X 1 and X 2 each independently represents —O—, —C(CH3)2—, or —C(CF3)2—.

[0026] When the structural unit B contains the structural unit (B1), it is possible to particularly lower the glass transition temperature and improve the solvent solubility. 1 and X 2 are each independently —O—, —C(CH3)2—, or —C(CF3)2—. X 1 is preferably at least one selected from the group consisting of —O—, —C(CH3)2—, and —C(CF3)2—, and more preferably —O—. 2 is preferably at least one selected from the group consisting of —O—, —C(CH3)2—, and —C(CF3)2—, and more preferably —O—. Specific examples of compounds represented by formula (b1) include at least one selected from the group consisting of 1,3-bis(3-aminophenoxy)benzene (TPE-M), 1,3-bis[2-(3-aminophenyl)-2-propyl]benzene, and 1,3-bis[2-(3-aminophenyl)-2-hexafluoropropyl]benzene, and more preferably 1,3-bis(3-aminophenoxy)benzene (TPE-M). That is, preferably, the structural unit (B1) includes a structural unit (B11) derived from a compound represented by formula (b11) below, and more preferably, the structural unit (B1) is a structural unit (B11) derived from a compound represented by formula (b11) below.

[0027] The proportion of the structural unit (B1) in the structural unit B is preferably 30 mol% or more, more preferably 50 mol% or more, and from the viewpoints of heat resistance, colorlessness, and strength, is even more preferably 70 mol% or more, still more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more, and preferably 100 mol% or less. The structural unit B may consist of only the structural unit (B1).

[0028] The structural unit B may consist solely of the structural unit (B1), or may include a structural unit other than the structural unit (B1). Preferably, however, the structural unit B further includes a structural unit (B2) derived from a compound represented by the following formula (b2) as a structural unit other than the structural unit (B1): (In the formula, X 3 and X 4 each independently represents —O—, —COO—, or —OCO—, and n is an integer of 2 to 10.

[0029] In formula (b2), X 3 and X 4 each independently represents —O—, —COO—, or —OCO—. 3 is preferably at least one selected from the group consisting of —O—, —COO—, and —OCO—, and more preferably —O—. 4 is preferably at least one selected from the group consisting of —O—, —COO—, and —OCO—, and more preferably —O—. The group represented by —OCO— is 3 n is an integer of 2 to 10, preferably an integer of 3 to 6, and more preferably an integer of 4 to 6.

[0030] The structural unit (B2) preferably includes at least one structural unit selected from the group consisting of a structural unit (B21) derived from a compound represented by the following formula (b21), a structural unit (B22) derived from a compound represented by the following formula (b22), a structural unit (B23) derived from a compound represented by the following formula (b23), a structural unit (B24) derived from a compound represented by the following formula (b24), and a structural unit (B25) derived from a compound represented by the following formula (b25), and more preferably includes a structural unit (B21) derived from a compound represented by the following formula (b21).

[0031] The compound represented by formula (b21) is 4,4'-hexamethylenebisoxyaniline (DA6MG), the compound represented by formula (b22) is 4,4'-pentamethylenebisoxyaniline (DA5MG), the compound represented by formula (b23) is 4,4'-trimethylenebisoxyaniline (DA3MG), the compound represented by formula (b24) is hexamethylenebis(4-aminobenzoate), and the compound represented by formula (b25) is trimethylenebis(4-aminobenzoate). When the structural unit B contains the structural unit (B2), the elastic modulus can be reduced.

[0032] The molar ratio of the structural unit (B1) to the structural unit (B2) [(B1) / (B2)] in the structural unit B is preferably 30 / 70 to 100 / 0, more preferably 40 / 60 to 100 / 0, and from the viewpoint of reducing the elastic modulus and improving laser peelability, is even more preferably 40 / 60 to 80 / 20, and still more preferably 40 / 60 to 60 / 40. When the molar ratio of the structural unit (B1) to the structural unit (B2) is 100 / 0, the structural unit B does not contain the structural unit (B2).

[0033] The proportion of the structural unit (B2) in the structural unit B is preferably 0 to 70 mol%, more preferably 0 to 60 mol%, even more preferably 20 to 60 mol%, and still more preferably 40 to 60 mol%. The total proportion of the structural unit (B1) and the structural unit (B2) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. The structural unit B may be composed only of the structural unit (B1) and the structural unit (B2).

[0034] The structural unit B may contain structural units other than the structural unit (B1) and the structural unit (B2). Diamines that provide such structural units are not particularly limited, but include aromatic diamines, alicyclic diamines, and aliphatic diamines, excluding compounds represented by formula (b1) and excluding compounds represented by formula (b2). In this specification, aromatic diamines refer to diamines containing one or more aromatic rings, alicyclic diamines refer to diamines containing one or more alicyclic rings but no aromatic rings, and aliphatic diamines refer to diamines containing neither aromatic nor alicyclic rings. The structural units other than the structural unit (B1) and the structural unit (B2) optionally contained in the structural unit B may be of one type, or two or more types.

[0035] Of the structural units other than the structural unit (B1) and the structural unit (B2), the structural unit (B3) derived from a compound represented by the following formula (b3) is preferred. (In the formula, L 7 , L 8 , L 9 and L 10 are each independently a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms; Z 3 and Z 4 each independently represents a divalent aliphatic group or a divalent aromatic group, and m is an integer of 1 to 200.

[0036] In formula (b3), Z 3 and Z 4The divalent aliphatic group or divalent aromatic group in the formula (I) may be substituted with a fluorine atom or may contain an oxygen atom. When an oxygen atom is contained as an ether bond, the carbon number shown below refers to the total number of carbon atoms contained in the aliphatic group or aromatic group. Examples of the divalent aliphatic group include divalent saturated or unsaturated aliphatic groups having 1 to 20 carbon atoms. The divalent aliphatic group preferably has 3 to 20 carbon atoms. Examples of the divalent saturated aliphatic group include alkylene groups and alkyleneoxy groups having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, ethylene group, propylene group, trimethylene group, tetramethylene group, hexamethylene group, octamethylene group, decamethylene group, and dodecamethylene group. Examples of the alkyleneoxy group include a propyleneoxy group and a trimethyleneoxy group. Examples of the divalent unsaturated aliphatic group include alkenylene groups having 2 to 20 carbon atoms, such as vinylene groups, propenylene groups, and alkylene groups having an unsaturated double bond at the terminal. Examples of the divalent aromatic group include arylene groups having 6 to 20 carbon atoms and aralkylene groups having 7 to 20 carbon atoms. Z 4 and Z 5 Specific examples of the arylene group having 6 to 20 carbon atoms in Z include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 4,4'-biphenylylene group, and a 2,6-naphthylene group. 3 and Z 4 As the alkyl group, a trimethylene group and a p-phenylene group are particularly preferred, with a trimethylene group being more preferred.

[0037] In formula (b3), L 7 ~L 10 In formula (b3), the monovalent aliphatic hydrocarbon having 1 to 5 carbon atoms includes a monovalent saturated or unsaturated aliphatic group. Examples of the monovalent saturated aliphatic group include an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, and a propyl group. Examples of the monovalent unsaturated aliphatic group include an alkenyl group having 2 to 5 carbon atoms, such as a vinyl group and a propenyl group. These groups may be substituted with a fluorine atom. The monovalent saturated aliphatic group is preferably a methyl group. L in formula (b3) 7 ~L 10Examples of the monovalent aromatic group having 6 to 10 carbon atoms in L include an aryl group having 6 to 10 carbon atoms, an aryl group substituted with an alkyl group having 7 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms. As the monovalent aromatic group, an aryl group is preferred, and a phenyl group is more preferred. 7 , L 8 , L 9 and L 10 is preferably at least one selected from the group consisting of a monovalent saturated aliphatic group and a monovalent aromatic group, more preferably at least one selected from the group consisting of a methyl group and a phenyl group, and even more preferably a methyl group. In formula (b3), m is an integer of 1 to 200, and preferably an integer of 10 to 100.

[0038] As described above, among the compounds represented by the above formula (b3), the compound represented by the following formula (b31) is preferred.

[0039] (In formula (b31), L 71 and L 81 are each independently a methyl group or a phenyl group, and m has the same definition as m in formula (b3), and the preferred range is also the same.

[0040] In formula (b31), m is an integer of 1 to 200, preferably an integer of 10 to 100. 71 and L 81 are each independently a methyl group or a phenyl group, preferably a methyl group. 71 The silicon atom to which the methyl group is bonded has L 81 Preferably, a methyl group is bonded as L 71 The silicon atom to which the phenyl group is bonded has L 81 Preferably, a phenyl group is bonded as the functional group equivalent. The functional group equivalent (amine equivalent) of the compound represented by formula (b3) is preferably 100 to 5,000 g / mol, more preferably 400 to 4,000 g / mol, and even more preferably 500 to 3,000 g / mol. The functional group equivalent means the mass of the compound represented by formula (b3) per mole of the functional group (amino group).

[0041] Among the compounds represented by the general formula (b3) above, examples of commercially available products include "X-22-9409", "X-22-1660B", "X-22-161A", and "X-22-161B" manufactured by Shin-Etsu Chemical Co., Ltd.

[0042] By including the structural unit (B3), the structural unit B can have a low modulus of elasticity, and can achieve both a low glass transition temperature and good heat resistance.

[0043] The molar ratio of the total of the structural units (B1) and (B2) to the structural unit (B3) in the structural unit B [((B1) + (B2)) / (B3)] is preferably 70 / 30 to 100 / 0, more preferably 80 / 20 to 100 / 0, even more preferably 85 / 15 to 100 / 0, still more preferably 85 / 15 to 99 / 1, even more preferably 85 / 15 to 97 / 3, and still more preferably 85 / 15 to 95 / 5. When the molar ratio of the total of the structural units (B1) and (B2) to the structural unit (B3) is 100 / 0, the structural unit B does not contain the structural unit (B3). By achieving this molar ratio, the elastic modulus can be lowered, and both a low glass transition temperature and heat resistance can be achieved.

[0044] The proportion of the structural unit (B3) in the structural unit B is preferably 0 to 30 mol%, more preferably 0 to 20 mol%, and even more preferably 0 to 15 mol%. When the structural unit B contains the structural unit (B3), the proportion of the compound that provides the structural unit (B3) in the structural unit B is preferably 1 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol%. The total proportion of the structural units (B1), (B2), and (B3) in the structural unit B is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. The structural unit B may consist solely of the structural unit (B1), the structural unit (B2), and the structural unit (B3).

[0045] <Characteristics of Polyimide Resin> The number average molecular weight of the polyimide resin is preferably 5,000 to 300,000 from the viewpoint of the mechanical strength of the resulting polyimide film. The number average molecular weight of the polyimide resin can be determined, for example, from a standard polymethyl methacrylate (PMMA) equivalent value measured by gel permeation chromatography.

[0046] The polyimide resin may contain a structure other than a polyimide chain (a structure formed by imide bonding between structural unit A and structural unit B). Examples of structures other than polyimide chains that can be contained in the polyimide resin include structures containing amide bonds. It is preferable that the polyimide resin contains a polyimide chain (a structure formed by imide bonding between structural unit A and structural unit B) as the main structure. Therefore, the proportion of polyimide chains in the polyimide resin is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 99% by mass or more. It is also preferably 100% by mass or less. Even more preferably, it may be 100% by mass, and the polyimide resin may be composed only of polyimide chains.

[0047] The polyimide resin preferably contains a structural unit represented by the following general formula (3). (In the formula, L 1 and L 2 are each independently a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, and m is an integer from 1 to 200.

[0048] In formula (3), L 1 and L 2 In the formula (3), examples of the monovalent aliphatic hydrocarbon having 1 to 5 carbon atoms include monovalent saturated or unsaturated aliphatic groups. Examples of the monovalent saturated aliphatic group include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, and propyl groups. A methyl group is preferred as the monovalent saturated aliphatic group. Examples of the monovalent unsaturated aliphatic group include alkenyl groups having 2 to 5 carbon atoms, such as vinyl and propenyl groups. These groups may be substituted with a fluorine atom. L in formula (3) 1 and L2 Examples of the monovalent aromatic group having 6 to 10 carbon atoms in L include an aryl group having 6 to 10 carbon atoms, an aryl group substituted with an alkyl group having 7 to 10 carbon atoms, and an aralkyl group having 7 to 10 carbon atoms. As the monovalent aromatic group, an aryl group is preferred, and a phenyl group is more preferred. 1 and L 2 is preferably at least one selected from the group consisting of a monovalent saturated aliphatic group and a monovalent aromatic group, more preferably at least one selected from the group consisting of a methyl group and a phenyl group, and even more preferably a methyl group. In formula (3), m is an integer of 1 to 200, preferably an integer of 10 to 100.

[0049] The structural unit represented by formula (3) may be introduced into the polyimide resin by any method, may be present in either the structural unit A or the structural unit B, or may be bonded to the structural unit without an imide bond. However, it is preferable that the structural unit be present in either or both of the structural unit A and the structural unit B, and it is more preferable that the structural unit be present in the structural unit A.

[0050] When the structural unit represented by formula (3) is present in structural unit A, the structural unit is preferably structural unit (A2). When the structural unit represented by formula (3) is present in structural unit B, the structural unit is preferably structural unit (B3).

[0051] [Method for Producing Polyimide Resin] The method for producing the polyimide resin of the present invention is not particularly limited, but is preferably a method for obtaining a polyimide resin by reacting a compound (tetracarboxylic acid component) that provides the above-mentioned structural unit A with a compound (diamine component) that provides the above-mentioned structural unit B. According to this method, a polyimide resin can be obtained directly from the tetracarboxylic acid component and the diamine component.

[0052] According to this production method, the polyimide resin can be produced by reacting a tetracarboxylic acid component containing a compound that provides the structural unit (A1) with a diamine component that contains a compound that provides the structural unit (B1).

[0053] Examples of compounds that provide the structural unit (A1) include compounds represented by formula (a1), but are not limited thereto and may also be derivatives thereof as long as they provide the same structural unit. Examples of such derivatives include tetracarboxylic acids corresponding to the tetracarboxylic dianhydride represented by formula (a1) and alkyl esters of the tetracarboxylic acids. Among these, the tetracarboxylic dianhydride represented by formula (a1) is preferred.

[0054] When the tetracarboxylic acid component contains a compound that provides the structural unit (A2), examples of the compound that provides the structural unit (A2) include, but are not limited to, a compound represented by formula (a2). Derivatives thereof may also be used as long as they provide the same structural unit. Examples of such derivatives include tetracarboxylic acids corresponding to the tetracarboxylic acid dianhydride represented by formula (a2) and alkyl esters of the tetracarboxylic acid. Among these, the tetracarboxylic acid dianhydride represented by formula (a2) is preferred.

[0055] The molar ratio [(A1) / (A2)] of the compound that provides the structural unit (A1) to the compound that provides the structural unit (A2) in the tetracarboxylic acid component is preferably 70 / 30 to 100 / 0, more preferably 80 / 20 to 100 / 0, even more preferably 85 / 15 to 100 / 0, still more preferably 85 / 15 to 99 / 1, even more preferably 85 / 15 to 97 / 3, and even more preferably 85 / 15 to 95 / 5. When this molar ratio is 100 / 0, the tetracarboxylic acid component does not contain a compound that provides the structural unit (A2). By achieving this molar ratio, the elastic modulus can be reduced, and both a low glass transition temperature and heat resistance can be achieved.

[0056] The proportion of the compound providing the structural unit (A1) in the tetracarboxylic acid component is preferably 30 mol% or more, more preferably 50 mol% or more. From the viewpoint of heat resistance and solvent solubility, it is even more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and preferably 100 mol% or less. The tetracarboxylic acid component may consist solely of the compound providing the structural unit (A1). The proportion of the compound providing the structural unit (A2) in the tetracarboxylic acid component is preferably 0 to 30 mol%, more preferably 0 to 20 mol%, even more preferably 0 to 15 mol%, even more preferably 1 to 15 mol%, even more preferably 3 to 15 mol%, and even more preferably 5 to 15 mol%. The total proportion of the compound providing the structural unit (A1) and the compound providing the structural unit (A2) in the tetracarboxylic acid component is even more preferably 90 mol% or more, and preferably 100 mol% or less. The tetracarboxylic acid component may consist solely of a compound that provides the structural unit (A1) and a compound that provides the structural unit (A2).

[0057] The tetracarboxylic acid component may contain a tetracarboxylic acid dianhydride other than the compound that provides the structural unit (A1) and the compound that provides the structural unit (A2). Examples of such tetracarboxylic acid dianhydrides include, but are not limited to, aromatic tetracarboxylic acid dianhydrides other than the compound represented by formula (a1), alicyclic tetracarboxylic acid dianhydrides, and aliphatic tetracarboxylic acid dianhydrides. The tetracarboxylic acid component may optionally contain one type of tetracarboxylic acid dianhydride or two or more types of tetracarboxylic acid dianhydrides.

[0058] Examples of compounds that provide the structural unit (B1) include, but are not limited to, compounds represented by formula (b1), and may also be derivatives thereof as long as they provide the same structural unit. Examples of such derivatives include diisocyanates corresponding to the compounds (diamines) represented by formula (b1). Of these, compounds represented by formula (b1) (i.e., diamines) are preferred.

[0059] The diamine component may contain structural units other than the compound that provides the structural unit (B1), but preferably also contains a compound that provides the structural unit (B2) derived from the compound represented by formula (b2). When the tetracarboxylic acid component contains a compound that provides the structural unit (B2), examples of the compound that provides the structural unit (B2) include, but are not limited to, the compound represented by formula (b2), and may also be a derivative thereof as long as it provides the same structural unit. Examples of such derivatives include diisocyanates corresponding to the compound represented by formula (b2) (diamine). Among these, the compound represented by formula (b2) (i.e., diamine) is preferred.

[0060] The molar ratio [(B1) / (B2)] of the compound that provides the structural unit (B1) to the compound that provides the structural unit (B2) in the diamine component is preferably 30 / 70 to 100 / 0, more preferably 40 / 60 to 100 / 0, and from the viewpoint of reducing the elastic modulus and improving laser peelability, is even more preferably 40 / 60 to 80 / 20, and still more preferably 40 / 60 to 60 / 40. When this molar ratio is 100 / 0, the diamine component does not contain a compound that provides the structural unit (B2).

[0061] The proportion of the compound providing the structural unit (B1) in the diamine component is preferably 30 mol% or more, more preferably 50 mol% or more. From the viewpoints of heat resistance, colorlessness, and strength, it is even more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and preferably 100 mol% or less. The diamine component may consist solely of the compound providing the structural unit (B1). The proportion of the compound providing the structural unit (B2) in the diamine component is preferably 0 to 70 mol%, more preferably 0 to 60 mol%, even more preferably 20 to 60 mol%, and even more preferably 40 to 60 mol%. The total proportion of the compound providing the structural unit (B1) and the compound providing the structural unit (B2) in the diamine component is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. The diamine component may consist of only a compound that provides the structural unit (B1) and a compound that provides the structural unit (B2).

[0062] The diamine component may contain diamines other than the compound that provides the structural unit (B1) and the compound that provides the structural unit (B2). Diamines that provide such structural units are not particularly limited, but include aromatic diamines, alicyclic diamines, and aliphatic diamines, excluding the compound represented by formula (b1) and the compound represented by formula (b2). The diamine component may optionally contain one type of diamine other than the structural unit (B1) and the structural unit (B2), or two or more types of diamines.

[0063] Among diamines other than the compound that provides the structural unit (B1) and the compound that provides the structural unit (B2), a compound that provides the structural unit (B3) is preferred. When the tetracarboxylic acid component contains a compound that provides the structural unit (B3), an example of the compound that provides the structural unit (B3) is a compound represented by formula (b3), but is not limited thereto, and a derivative thereof may also be used as long as it provides the same structural unit. An example of such a derivative is a diisocyanate corresponding to the compound (diamine) represented by formula (b3). Of these, a compound represented by formula (b3) (i.e., a diamine) is preferred.

[0064] The molar ratio of the compound that provides the structural unit (B1) and the compound that provides the structural unit (B2) in the diamine component to the compound that provides the structural unit (B3) [((B1) + (B2)) / (B3)] is preferably 70 / 30 to 100 / 0, more preferably 80 / 20 to 100 / 0, even more preferably 85 / 15 to 100 / 0, even more preferably 85 / 15 to 99 / 1, even more preferably 85 / 15 to 97 / 3, and even more preferably 85 / 15 to 95 / 5. When the molar ratio of the compound that provides the structural unit (B1) and the compound that provides the structural unit (B2) to the compound that provides the structural unit (B3) is 100 / 0, the diamine component does not contain the compound that provides the structural unit (B3). By achieving this molar ratio, the elastic modulus of the resulting polyimide resin can be reduced, and both a low glass transition temperature and heat resistance can be achieved.

[0065] The ratio of the compound that provides the structural unit (B3) in the diamine component is preferably 0 to 30 mol%, more preferably 0 to 20 mol%, and even more preferably 0 to 15 mol%. When the diamine component contains a compound that provides the structural unit (B3), the ratio of the compound that provides the structural unit (B3) in the diamine component is preferably 1 to 30 mol%, more preferably 3 to 20 mol%, and even more preferably 5 to 15 mol%. The total ratio of the compound that provides the structural unit (B1), the compound that provides the structural unit (B2), and the compound that provides the structural unit (B3) in the diamine component is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. The diamine component may consist solely of the compound that provides the structural unit (B1), the compound that provides the structural unit (B2), and the compound that provides the structural unit (B3).

[0066] In the present invention, the ratio of the amount of the tetracarboxylic acid component to the amount of the diamine component used in the production of the polyimide resin is preferably 0.9 to 1.1 moles of the diamine component per mole of the tetracarboxylic acid component.

[0067] In the present invention, in addition to the tetracarboxylic acid component and diamine component described above, a terminal blocking agent may also be used in the production of the polyimide resin. Monoamines or dicarboxylic acids are preferred as terminal blocking agents. The amount of terminal blocking agent to be introduced is preferably 0.0001 to 0.1 mol, more preferably 0.001 to 0.06 mol, per mol of the tetracarboxylic acid component. Examples of monoamine terminal blocking agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, and 4-methylaniline, with benzylamine and aniline being preferred. Dicarboxylic acids are preferred as dicarboxylic acid terminal blocking agents, and a portion of these may be ring-closed. Examples include phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenonedicarboxylic acid, 3,4-benzophenonedicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid, with phthalic acid and phthalic anhydride being preferred.

[0068] The method for reacting the tetracarboxylic acid component and the diamine component is not particularly limited, and known methods can be used. Specific reaction methods include (1) a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor, stirred at 0 to 80°C for 0.5 to 30 hours, and then heated to carry out the imidization reaction, (2) a method in which the diamine component and the reaction solvent are charged into a reactor and dissolved, and then the tetracarboxylic acid component is charged, stirred at room temperature (0 to 80°C) for 0.5 to 30 hours as needed, and then heated to carry out the imidization reaction, and (3) a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor, and immediately heated to carry out the imidization reaction.

[0069] The organic solvent (reaction solvent) used in the production of the polyimide resin may be any solvent that does not inhibit the imidization reaction and can dissolve the resulting polyimide resin, such as an aprotic solvent, a phenolic solvent, an ether solvent, or a carbonate solvent.

[0070] Specific examples of the aprotic solvent include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; lactone solvents such as γ-butyrolactone (GBL) and γ-valerolactone; glycol solvents such as diethylene glycol dimethyl ether, triethylene glycol, and triethylene glycol dimethyl ether; phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphine triamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as acetone, cyclopentanone, cyclohexanone, and methylcyclohexanone; amine solvents such as picoline and pyridine; and ester solvents such as 2-methoxy-1-methylethyl acetate.

[0071] Specific examples of phenol-based solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. Specific examples of ether-based solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl]ether, tetrahydrofuran, and 1,4-dioxane. Specific examples of carbonate-based solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate. Among the above reaction solvents, aprotic solvents are preferred, with amide-based solvents and lactone-based solvents being more preferred, and lactone-based solvents being even more preferred. The above reaction solvents may be used alone or in combination.

[0072] The imidization reaction is preferably carried out while removing water generated during the production using a Dean-Stark apparatus, etc. By performing such an operation, the degree of polymerization and the imidization rate can be further increased.

[0073] In the imidization reaction, a known imidization catalyst can be used. Examples of the imidization catalyst include base catalysts and acid catalysts. Examples of base catalysts include organic base catalysts such as pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine (TEA), tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, and N,N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate. Examples of acid catalysts include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, hydroxybenzoic acid, terephthalic acid, benzenesulfonic acid, paratoluenesulfonic acid, and naphthalenesulfonic acid. The imidization catalysts described above may be used alone or in combination of two or more. Among the above, from the viewpoint of ease of handling, it is preferable to use a base catalyst, it is more preferable to use an organic base catalyst, and it is even more preferable to use at least one selected from the group consisting of triethylamine and triethylenediamine.

[0074] The temperature of the imidization reaction is preferably 120 to 250° C., more preferably 160 to 200° C., from the viewpoint of the reaction rate and suppression of gelation, etc. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the produced water.

[0075] [Polyimide Varnish and Temporary Fixing Material Composition] The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. That is, the polyimide varnish of the present invention contains the polyimide resin of the present invention and an organic solvent, and the polyimide resin is dissolved in the organic solvent. The organic solvent is not particularly limited as long as it dissolves the polyimide resin, but it is preferable to use the compounds described above as reaction solvents used in producing the polyimide resin, either alone or in combination of two or more. The polyimide varnish of the present invention may be a polyimide solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or may be a polyimide solution diluted by adding a solvent to the polyimide solution.

[0076] The polyimide resin of the present invention is solvent-soluble, allowing it to be made into a highly concentrated varnish that is stable at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass, more preferably 10 to 30% by mass, of the polyimide resin of the present invention. The viscosity of the polyimide varnish is preferably 1 to 200 Pa·s, more preferably 1 to 100 Pa·s. The viscosity of the polyimide varnish is measured at 25°C using an E-type viscometer. The polyimide varnish of the present invention may also contain various additives, such as inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, surfactants, leveling agents, defoamers, fluorescent brighteners, crosslinking agents, polymerization initiators, and photosensitizers, as long as they do not impair the required properties of the polyimide resin and temporary fixing material. The method for producing the polyimide varnish of the present invention is not particularly limited, and known methods can be used.

[0077] The temporary fixing material composition of the present invention contains the polyimide resin. Therefore, the polyimide varnish can also be used as a temporary fixing material composition. The temporary fixing material composition of the present invention is preferably one in which the polyimide resin of the present invention is dissolved in an organic solvent. That is, the temporary fixing material composition of the present invention preferably contains the polyimide resin of the present invention and an organic solvent, and more preferably the polyimide resin is dissolved in the organic solvent. The organic solvent is not particularly limited as long as it dissolves the polyimide resin, but it is preferable to use the compounds described above as reaction solvents used in producing the polyimide resin, either alone or in a mixture of two or more. The temporary fixing material composition of the present invention may be a polyimide solution itself in which a polyimide resin obtained by a polymerization method is dissolved in a reaction solvent, or may be a polyimide solution diluted by further adding a solvent to the polyimide solution.

[0078] Because the polyimide resin of the present invention is solvent-soluble, it can be made into a high-concentration temporary fixing material composition that is stable at room temperature. The temporary fixing material composition of the present invention preferably contains 5 to 40 mass %, and more preferably 10 to 30 mass %, of the polyimide resin of the present invention. The viscosity of the temporary fixing material composition is preferably 1 to 200 Pa·s, and more preferably 1 to 100 Pa·s. The viscosity of the temporary fixing material composition is a value measured at 25°C using an E-type viscometer. In addition, the temporary fixing material composition of the present invention may contain various additives, such as inorganic fillers, adhesion promoters, release agents, flame retardants, UV stabilizers, surfactants, leveling agents, antifoaming agents, fluorescent brightening agents, crosslinking agents, polymerization initiators, and photosensitizers, within ranges that do not impair the required properties of the polyimide resin and temporary fixing material.

[0079] [Polyimide Film] The polyimide film of the present invention contains the polyimide resin described above, and therefore has a low elastic modulus, a low glass transition temperature, and heat resistance, excellent solvent solubility, and a low light transmittance at a wavelength of 355 nm.

[0080] The preferred physical properties of the polyimide film of the present invention are as follows. When the film has a thickness of 30 μm, the light transmittance at a wavelength of 355 nm is preferably 1.0% or less, more preferably 0.5% or less, even more preferably 0.2% or less, and even more preferably 0.1% or less. The glass transition temperature is preferably 210°C or less, more preferably 180°C or less, and even more preferably 160°C or less. The 5% weight loss temperature is preferably 450°C or more, more preferably 480°C or more, and even more preferably 500°C or more. The weight loss rate when held at 350°C for 60 minutes is preferably 1.0% or less, more preferably 0.7% or less, and even more preferably 0.4% or less. When the film has a thickness of 30 μm, the tensile modulus is preferably 3.0 GPa or less, more preferably 2.6 GPa or less, and even more preferably 2.3 GPa or less. The above-mentioned physical properties of the present invention can be specifically measured by the methods described in the examples.

[0081] The polyimide film of the present invention contains the polyimide resin, and has a low elastic modulus, a low glass transition temperature, and heat resistance, and has excellent solvent solubility and a low light transmittance at a wavelength of 355 nm. Therefore, the polyimide film of the present invention can be suitably used as a temporary fixing material by forming the polyimide film of the present invention on a semiconductor electronic circuit formation substrate by the above-mentioned method.

[0082] There are no particular restrictions on the thickness of the polyimide film of the present invention, but when used as a temporary fixing material, it is preferably 1 to 250 μm, more preferably 5 to 100 μm, even more preferably 8 to 80 μm, and even more preferably 10 to 80 μm. The thickness of the polyimide film can be easily controlled by adjusting the solids concentration and viscosity of the varnish. When using the polyimide film as a temporary fixing material, the thickness can be easily controlled by adjusting the solids concentration and viscosity of the temporary fixing material composition.

[0083] The method for producing the polyimide film of the present invention is not particularly limited, and known methods can be used. For example, a method in which the varnish of the present invention is applied to a support and heated is exemplified. Specifically, a method in which the varnish is applied to a smooth support such as a glass plate, a metal plate, or plastic, and then organic solvents contained in the varnish, such as reaction solvents and dilution solvents, are removed by heating is exemplified. The polyimide varnish containing the polyimide resin of the present invention is suitably used as a raw material for a temporary fixing material. When the polyimide film of the present invention is used as a temporary fixing material, a semiconductor electronic circuit formation substrate is used as the support.

[0084] Examples of coating methods include known coating methods such as spin coating, slit coating, and blade coating. Among these, spin coating is preferred from the viewpoints of improving film uniformity and workability. A preferred method for removing the organic solvent contained in the varnish by heating is to evaporate the organic solvent at a temperature of 150°C or less to make it tack-free, and then dry it at a temperature above the boiling point of the organic solvent used (not particularly limited, but preferably 200 to 500°C). Drying is also preferred in an air or nitrogen atmosphere. The pressure of the drying atmosphere may be reduced, normal pressure, or increased pressure. The method for peeling the polyimide film formed on the support from the support is not particularly limited, but examples include laser lift-off, a method using a sacrificial layer for peeling (a method in which a release agent is applied to the surface of the support in advance), and a method using a release agent. When the polyimide film of the present invention is used as a temporary fixing material, the semiconductor electronic circuit-forming substrate and the support substrate are peeled off, and the temporary fixing material is finally removed. Therefore, a method of dissolving the polyimide film serving as the temporary fixing material in a solvent or a method of peeling by irradiating a laser from the support substrate side can be used.

[0085] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples in any way.

[0086] [Physical Properties and Evaluation of Polyimide Resin] The physical properties of the polyimide films obtained in the Examples and Comparative Examples were measured and evaluated by the methods described below, and the polyimide resins were evaluated.

[0087] (1) Thickness of Polyimide Film The thickness of the polyimide film was measured using a digital gauge "SA-S110 / 03N" manufactured by Citizen Finedevices Co., Ltd.

[0088] (2) Total Light Transmittance and Yellow Index (YI) The total light transmittance and YI of a polyimide film were measured after peeling from a glass plate, with the total light transmittance measured in accordance with JIS K7361-1:1997 and the YI measured in accordance with ASTM E313-05 (D light source, 65°) using a color and turbidity simultaneous measuring instrument "COH7700" manufactured by Nippon Denshoku Industries Co., Ltd. The larger the total light transmittance value of the polyimide film, the more excellent the transparency of the polyimide resin. The larger the YI value of the polyimide film, the more excellent the colorlessness of the polyimide resin.

[0089] (3) Light transmittance at a wavelength of 355 nm The light transmittance of a polyimide film at a wavelength of 355 nm was determined by the following method for the polyimide film after peeling it from the glass plate. Measurement was performed using an ultraviolet-visible-near-infrared spectrophotometer "UV-3600Plus+MPC-603A" manufactured by Shimadzu Corporation. The smaller the light transmittance value at a wavelength of 355 nm, the better the LLO (laser lift-off) releasability. In Table 1, "<0.1" indicates "less than 0.1%."

[0090] (4) Glass Transition Temperature (Tg) Using a thermomechanical analyzer "TMA 7100C" manufactured by Hitachi High-Tech Science Corporation, TMA measurement was performed using a sample size of 4 mm x 20 mm in tension mode under conditions of a load of 50 mN and a heating rate of 10°C / min, raising the temperature from 40°C to 300°C, and the point at which an inflection point of elongation was observed was determined as the glass transition temperature (Tg) by extrapolation.

[0091] (5) 5% Weight Loss Temperature (Td5%) A Hitachi High-Tech Science Corporation "NEXTA STA200RV" thermogravimetric and differential thermal analyzer was used. The sample (polyimide film) was heated from 40°C to 50°C at a heating rate of 10°C / min, held at 150°C for 30 minutes to remove moisture, and then heated to 500°C. The temperature at which the weight decreased by 5% compared to the weight after holding at 150°C for 30 minutes was defined as the 5% weight loss temperature. The higher the weight loss temperature, the better the heat resistance. In Table 1, samples with a Td5% value greater than 500°C (those that did not lose 5% weight even at 500°C) were designated ">500."

[0092] (6) Weight Loss Rate (%) A differential thermal thermogravimetric simultaneous analyzer "NEXTA STA200RV" manufactured by Hitachi High-Tech Science Corporation was used. The sample (polyimide film) was heated from 40°C to 150°C at a heating rate of 10°C / min, held at 150°C for 30 minutes to remove moisture, and then heated to 350°C. The weight at 350°C was used as the reference weight, and the weight loss rate after holding at 350°C for 60 minutes was taken as the weight loss rate. The smaller the weight loss rate, the better the heat resistance.

[0093] (7) Tensile Modulus and Tensile Strength The tensile modulus and tensile strength of the polyimide film were measured using a tensile tester "Strograph VG-1E" manufactured by Toyo Seiki Co., Ltd. in accordance with JIS K7127: 1999. The lower the modulus, the better the bonding when used as a temporary fixing material, which is preferable.

[0094] (8) Solvent Solubility (After Post-Bake) A polyimide film was immersed in GBL (γ-butyrolactone) and cyclohexanone at room temperature (25°C) and stirred with a magnetic stirrer to evaluate solubility. The concentration during evaluation was 0.2% (w / w). The evaluation results were as follows. Being soluble in solvents with low water absorption such as GBL (γ-butyrolactone) and cyclohexanone allows the use of low water absorption solvents in the peeling process, and is less susceptible to the effects of humidity and moisture during peeling, making it preferable. A: Dissolved within 1 hour. B: Not dissolved within 1 hour, but dissolved within 24 hours. C: Not dissolved within 24 hours, but dissolved within 72 hours. D: Not dissolved within 72 hours (insoluble).

[0095] (9) Solvent Solubility (After Annealing at 350°C for 1 Hour) After forming a polyimide film on a silicon wafer using the method described in the Examples, the film was heated in a hot air dryer at 350°C for 60 minutes under a nitrogen atmosphere, and then its solubility was evaluated. The film was immersed in GBL (γ-butyrolactone) or cyclohexanone at room temperature (25°C) and stirred with a magnetic stirrer to evaluate its solubility. The sample size during evaluation was 10 mm x 20 mm, and the amount of each solvent was 50 mL. The evaluation results were as follows. Being soluble in solvents with low water absorption, such as GBL (γ-butyrolactone) and cyclohexanone, allows the use of low water absorption solvents in the peeling process and is less susceptible to the effects of humidity and moisture during peeling, making it preferable. A: Dissolved within 1 hour. B: Not dissolved within 1 hour, but dissolved within 24 hours. C: Not dissolved within 24 hours, but dissolved within 72 hours. D: Not dissolved within 72 hours (insoluble).

[0096] <Abbreviations for Components, etc.> The tetracarboxylic acid components and diamine components used in the examples and comparative examples, and their abbreviations, are as follows.

[0097] (Tetracarboxylic acid components) 6F-BPADA: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride (compound represented by formula (a11), manufactured by Air Water Performance Chemicals Inc.) BPF-PA: 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (compound represented by formula (a12), manufactured by JFE Chemical Corporation) X-22-168AS: both-end carboxylic acid anhydride-modified silicone (viscosity at 25°C: 160 mm 2 / s, functional group equivalent: 518 g / mol, manufactured by Shin-Etsu Chemical Co., Ltd., compound represented by formula (a21)) BPADA: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (compound represented by the following formula, manufactured by Tokyo Chemical Industry Co., Ltd.) HPMDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride (compound represented by the following formula, manufactured by Mitsubishi Gas Chemical Company, Inc.)

[0098] (Diamine component) TPE-M: 1,3-bis(3-aminophenoxy)benzene (compound represented by formula (b11), manufactured by Seika Corporation) DA5MG: 4,4'-pentamethylenebisoxyaniline (compound represented by formula (b22), manufactured by Seika Corporation)

[0099] The abbreviations for the solvents and catalysts used in the examples and comparative examples are as follows: GBL: γ-butyrolactone (manufactured by Mitsubishi Chemical Corporation) TEA: triethylamine (manufactured by Kanto Chemical Co., Ltd.)

[0100] Example 1: 29.234 g (0.100 mol) of TPE-M and 136.802 g of GBL were placed in a 500 mL five-neck round-bottom flask equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a Dean-Stark condenser, a thermometer, and a glass end cap. The mixture was stirred at 200 rpm under a nitrogen atmosphere at a system temperature of 70°C to obtain a solution. 62.844 g (0.100 mol) of 6F-BPADA and 25.650 g of GBL were added in one portion to the solution, followed by the addition of 0.506 g of TEA as an imidization catalyst and 8.550 g of GBL. The mixture was heated in a mantle heater, and the reaction system temperature was raised to 190°C over approximately 20 minutes. The temperature in the reaction system was maintained at 190°C and refluxed for 3 hours while collecting the distilled components. Subsequently, 182.894 g of GBL was added so that the solids concentration was 20% by mass, and the temperature in the reaction system was cooled to 50°C to obtain a polyimide varnish containing a polyimide resin. The resulting polyimide varnish was then applied to a silicon wafer by spin coating, held on a hot plate at 120°C for 20 minutes, and then heated in an air atmosphere in a hot air dryer at 220°C for 30 minutes to evaporate the solvent, yielding a polyimide film. The physical properties and evaluation results of the film are shown in Table 1.

[0101] Examples 2, 3, 5 and Comparative Example 2 A solution containing a polyimide resin was obtained in the same manner as in Example 1, except that 6F-BPADA was replaced with the tetracarboxylic acid component shown in Table 1. GBL was added to the obtained solution so that the solids concentration was 20% by mass, and the mixture was homogenized to obtain a polyimide varnish containing a polyimide resin. The obtained polyimide varnish was then applied to a silicon wafer by spin coating, held on a hot plate at 120°C for 20 minutes, and then heated in a hot air dryer at 220°C for 30 minutes in an air atmosphere to evaporate the solvent, yielding a polyimide film. The physical properties and evaluation results of the film are shown in Table 1.

[0102] Example 4 A solution containing a polyimide resin was obtained in the same manner as in Example 1, except that TPE-M was replaced with the diamine component shown in Table 1. GBL was added to the obtained solution so that the solids concentration was 20% by mass, and the mixture was homogenized to obtain a polyimide varnish containing a polyimide resin. The obtained polyimide varnish was then applied to a silicon wafer by spin coating, held on a hot plate at 120°C for 20 minutes, and then heated in a hot air dryer at 220°C for 30 minutes in an air atmosphere to evaporate the solvent, yielding a polyimide film. The physical properties and evaluation results of the film are shown in Table 1.

[0103] Comparative Example 1 A solution containing a polyimide resin was obtained in the same manner as in Example 1, except that 6F-BPADA was changed to the tetracarboxylic acid component shown in Table 1. GBL was added to the obtained solution so that the solids concentration would be 20% by mass, but the compatibility with GBL was poor and homogenization was not possible. Therefore, NMP was added to the obtained solution so that the solids concentration would be 20% by mass, and homogenization was performed to obtain a polyimide varnish containing a polyimide resin.

[0104]

[0105] As shown in Table 1, the polyimide resins (polyimide films) of the examples exhibit low light transmittance at a wavelength of 355 nm and low glass transition temperatures, yet exhibit high weight loss temperatures, low elastic moduli, and excellent solvent solubility with GBL and cyclohexanone. This indicates that the polyimide resins of the present invention have excellent low-temperature adhesion due to their low elastic moduli and low glass transition temperatures. Furthermore, the polyimide resins of the present invention exhibit high weight loss temperatures, thereby providing heat resistance for use in the manufacturing process of semiconductor electronic components. Furthermore, the polyimide resins of the present invention exhibit low light transmittance at a wavelength of 355 nm, enabling laser peeling. Their excellent solvent solubility with GBL and cyclohexanone also indicates that solvent peeling is possible with various solvents. As described above, the polyimide resins of the present invention can be suitably used as temporary fixing materials, and temporary fixing material compositions containing the polyimide resins possess the excellent properties described above.

Claims

1. A polyimide resin having a structural unit A derived from a tetracarboxylic dianhydride and a structural unit B derived from a diamine, The structural unit A includes a structural unit (A1) derived from a compound represented by the following formula (a1): A polyimide resin, wherein the structural unit B comprises a structural unit (B1) derived from a compound represented by the following formula (b1): 【Chemistry 1】 (In the formula, Z is a group represented by the following formula (1) or a group represented by the following formula (2). X 1 and X 2 are each independently —O—, —C(CH 3 ) 2 -, -C(CF 3 ) 2 - indicates.) 【Chemistry 2】 (In formula (2), R 1 and R 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms.

2. 2. The polyimide resin according to claim 1, wherein the ratio of the structural unit (A1) in the structural unit A is 30 to 100 mol %.

3. 3. The polyimide resin according to claim 1, wherein the ratio of the structural unit (B1) in the structural unit B is 30 to 100 mol %.

4. 3. The polyimide resin according to claim 1, wherein the structural unit (A1) includes at least one selected from the group consisting of a structural unit (A11) derived from a compound represented by the following formula (a11) and a structural unit (A12) derived from a compound represented by the following formula (a12): 【Chemistry 3】

5. The polyimide resin according to claim 1 or 2, wherein the structural unit (B1) includes a structural unit (B11) derived from a compound represented by the following formula (b11): 【Chemistry 4】

6. The polyimide resin according to claim 1 or 2, wherein the structural unit B further comprises a structural unit (B2) derived from a compound represented by the following formula (b2): 【Chemistry 5】 (In the formula, X 3 and X 4 each independently represents -O-, -COO-, or -OCO-; and n is an integer of 2 to 10.

7. The polyimide resin according to claim 1 or 2, comprising a structural unit represented by the following general formula (3): 【Chemistry 6】 (In the formula, L 1 and L 2 are each independently a monovalent aliphatic hydrocarbon group having 1 to 5 carbon atoms or a monovalent aromatic group having 6 to 10 carbon atoms, and m is an integer from 1 to 200.

8. A polyimide varnish comprising the polyimide resin according to claim 1 or 2 and an organic solvent.

9. A polyimide film comprising the polyimide resin according to claim 1 or 2.

10. A temporary fixing material composition comprising the polyimide resin according to claim 1 or 2.

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