High-stretch polyimide film

Abstract

We provide a polyimide film that possesses high elongation, low stress, and a high thermal decomposition temperature. [Solution] A polyimide film comprising a polyimide containing structural units derived from aromatic acid dianhydrides and structural units derived from diamines, characterized in that it does not have a clear yield point in its stress-strain curve.

Description

[Technical Field]

[0001] This invention relates to a polyimide film. The polyimide film of this invention is a material that possesses high elongation, low stress, and heat resistance. [Background technology]

[0002] Patent Document 1 discloses a polyurethane that is excellent in elastic recovery and flexibility. However, while such polyurethane is excellent in flexibility, it has insufficient heat resistance. Patent Document 2 discloses a urethane acrylate resin film that exhibits excellent heat resistance in addition to flexibility and resilience by forming chemical crosslinks at a low density within the film. However, while the heat resistance of such urethane acrylate resins is improved to some extent, it does not possess sufficient heat resistance to withstand harsh manufacturing processes. Furthermore, because the crosslink structure is low density, the intermolecular distances tend to widen, resulting in high flexibility. On the other hand, because there is little entanglement of molecular chains, it is easily torn. Improvement is needed, especially for applications that require repeated use or use in a stretched state for extended periods, as sufficient strength is necessary.

[0003] Patent Document 3 discloses a polyimide film that is flexible, conforms to stretching and contracting, and has excellent heat resistance. However, since such polyimides are composed only of aromatic diamines and aromatic acid anhydrides, the intermolecular interactions are strong, and micro-Brownian motion does not easily occur. As a result, there is a problem that the film has a yield point and high stress, making it difficult to stretch with little force.

[0004] Furthermore, polyimides having a siloxane skeleton in the main chain are attracting attention for their elasticity, hydrophobicity, and mechanical properties. Patent Document 4 discloses a laminate of a urethane resin having urethane bonds and siloxane bonds and a silicone-modified polyimide resin. Patent Document 5 discloses a silicone-modified polyimide resin. However, further improvements in physical properties are needed. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6413298 [Patent Document 2] Patent No. 7226324 [Patent Document 3] International Publication No. 2022 / 259841 [Patent Document 4] Japanese Patent Publication No. 2022-156876 [Patent Document 5] Japanese Patent Publication No. 2018-11931 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a polyimide film that has high elongation, low stress, and a high thermal decomposition temperature, as well as a laminated device using the same. [Means for solving the problem]

[0007] As a result of diligent research, the inventors of the present invention have found that polyimides containing structural units with a specific configuration can solve the above problems, and have completed the present invention.

[0008] In other words, the present invention relates to a polyimide film comprising a polyimide containing structural units derived from a diamine and structural units derived from an aromatic acid dianhydride, characterized in that it does not have a yield point in the stress-strain curve obtained by a tensile test.

[0009] The polyimide film of the present invention is preferably a polyimide film having an elongation at break of 100% or more and a stress at 100% elongation of 10 MPa or less. Here, an elongation at break of 100% or more means that the film does not break at 100% elongation when a tensile test is carried out under the condition of a speed of 10 mm / min. The stress at 100% elongation means the stress of the film when a tensile test is carried out under the condition of an elongation rate of 10 mm / min and the film elongation reaches 100%, that is, when the length of the film becomes twice the length before the start of elongation.

[0010] A stress-strain curve is a physical property representing the mechanical properties of an object measured by a tensile testing machine, and is drawn with strain on the horizontal axis and stress on the vertical axis. When the external force acting on the object is increased, in the stress-strain curve, the phenomenon that the proportional relationship between stress and strain is broken and strain increases preferentially is called yielding, and the stress at that point is called the yield point. When the tensile force exceeds the yield point, the film starts irreversible plastic deformation.

[0011] In the present invention, when the film is stretched in a tensile test to increase the strain of the film, the case where a phenomenon that the stress decreases with respect to the increasing strain is observed as shown by the upper curve in FIG. 1 is regarded as having a yield point, and the case where such a phenomenon that the stress decreases with respect to the increasing strain is not observed as shown by the lower curve in FIG. 1 is regarded as having no yield point.

[0012] The polyimide film of the present invention has a low initial stress when the film is pulled. Therefore, the polyimide film of the present invention is soft and does not need to be strongly pulled when stretched. In particular, it can be easily stretched to 100% or more without breaking. The polyimide film of the present invention is preferably a polyimide film having an elongation at break of 100% or more and a stress at 100% elongation of 10 MPa or less when a tensile test is carried out at a speed of 10 mm / min.

[0013] Furthermore, the polyimide film of the present invention has high heat resistance and does not easily decompose even when heated at high temperatures. Preferably, the polyimide film of the present invention has a 5% weight loss temperature (Td5) of 350°C or higher. Here, the 5% weight loss temperature (Td5) is an indicator of heat degradation resistance, and is the temperature at which the weight retention rate of the sample becomes 95% when heated from room temperature at a constant heating rate (10°C / min to 20°C / min), that is, the temperature at which a 5% weight loss is observed from the start of heating. [Effects of the Invention]

[0014] The polyimide film of the present invention does not have a yield point in the stress-strain curve during tensile testing, making it resistant to plastic deformation and easy to restore to its original shape after stretching. The polyimide film of the present invention exhibits superior elasticity and heat resistance compared to conventional polyimide films, silicone-modified polyimide films, or other resin films.

[0015] In particular, the polyimide film of the present invention has a low initial stress when stretched, allowing it to be stretched with little force. The polyimide film of the present invention is soft and can be easily stretched to more than 100% without breaking. At the same time, the polyimide film of the present invention is resistant to plastic deformation and easily returns to its original shape after stretching.

[0016] Furthermore, the polyimide film of the present invention has high heat resistance and does not deteriorate easily even when heated at high temperatures. In addition, the polyimide film of the present invention has high tear propagation resistance and has high resistance to forces that tear the film. [Brief explanation of the drawing]

[0017] [Figure 1] Stress-strain curve of polyimide film obtained by tensile testing [Modes for carrying out the invention]

[0018] The polyimide film of the present invention is a polyimide film comprising a polyimide containing structural units derived from a diamine and structural units derived from an aromatic acid dianhydride, and is characterized in that it does not have a yield point in the stress-strain curve obtained by a tensile test.

[0019] The polyimide film of the present invention is composed of a polyimide containing structural units derived from aromatic dianhydrides and structural units derived from diamines. The proportion (molar ratio) of diamine-derived structural units and dianhydride-derived structural units constituting the polyimide used in the present invention is the same as the proportion (molar ratio) of diamine and dianhydride used when producing polyimide by polymerization.

[0020] The polyimide constituting the polyimide film of the present invention preferably contains 25 mol% or more of structural units derived from silicon-containing diamines represented by general formula (1) of the total structural units derived from diamines. [ka] (In the formula, R 1 and R 2 Each of these is independently a divalent aliphatic hydrocarbon group having 3 to 20 carbon atoms, and R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each of these is independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 18 carbon atoms, where m is an integer greater than or equal to 0 and less than n, and n is an integer greater than or equal to 1.

[0021] The polyimide constituting the polyimide film of the present invention preferably has at least one organic group represented by general formula (2).

[0022] [ka] (In the formula, X represents the groups O, S, SO2, C(CF3)2, or C(CH3)2.)

[0023] The polyimide constituting the polyimide film of the present invention preferably contains 25 mol% or more of structural units derived from siloxane, polyether diamine or dimer diamine.

[0024] The polyimide constituting the polyimide film of the present invention is polymerized using a diamine having two amino groups in the molecule and an aromatic anhydride having two acid anhydride groups in the molecule. As the specific diamine, siloxane diamine, polyether diamine or dimer diamine is used. The polyimide preferably contains 25 mol% or more of the structural units derived from these diamines based on the total amount of the structural units derived from the diamines. For this purpose, in the polymerization, the amount of these diamines used is formulated to be 25 mol% or more of the total amount of the diamines used.

[0025] Here, as the siloxane diamine, a silicon-containing diamine represented by the formula (1) is preferably used. The silicon-containing diamine may be used alone or in combination with one or more other diamines. When combining the silicon-containing diamine and the diamine, the content of the silicon-containing diamine is 25 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, and most preferably 65 mol% or more of the total diamines.

[0026] [Chemical formula] (In the formula, R 1 and R 2 are each independently a divalent aliphatic hydrocarbon group having 3 to 20 carbon atoms, and R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 18 carbon atoms, m is an integer of 0 or more and is smaller than n, and n is an integer of 1 or more.)

[0027] In the silicon-containing diamine represented by formula (1) above, m and n, which represent the number of repeating units of the siloxane unit in the main chain, may have a molecular distribution, but m is preferably 0 or 1, with 0 being preferred, and n is preferably 1 to 10, with 7 to 10 being more preferred. Furthermore, the preferred number average molecular weight of the silicon-containing diamine is 200 to 2000, a more preferred number average molecular weight is 400 to 1500, and even more preferably 500 to 1000. The number average molecular weight of the silicon-containing diamine was calculated as twice the amine equivalent.

[0028] Also, in equation (1) above, R 1 and R 2 Each of these is independently a divalent aliphatic hydrocarbon group having 3 to 20 carbon atoms. Preferably, it is an alkylene group having 1 to 6 carbon atoms, particularly a methylene group, an ethylene group, or a propylene group. Also, R 3 , R 4 , R 5 , R 6 , R 7 and R 8 Each of these is independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or an aromatic group having 6 to 18 carbon atoms. Preferably, it is a methyl group. In formula (1), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 They may be different from each other or the same.

[0029] Particularly preferred silicon-containing diamines are those having a siloxane skeleton represented by the following formula (3). [ka] (In the formula, p is an integer between 1 and 20.)

[0030] Polyetherdiamines, which are raw materials for polyimides, are diamines having a skeleton represented by the following formula (4). [ka] (In the formula, R 9 , R 10 and R 11 Each of these is independently a hydrogen atom, a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, or an aromatic group having 6 to 18 carbon atoms; a, b, c, and d are integers greater than or equal to 1; and x, y, and z are integers greater than or equal to 0.

[0031] Dimer amines, which are raw materials for polyimides, are dimers of unsaturated higher aliphatic monoamines and can be prepared by the following methods. For example, an unsaturated fatty acid or its ester, a higher unsaturated nitrile, or a higher unsaturated alcohol having 1 to 4 unsaturated bonds in the molecule, preferably 1 or 2, and having 11 to 22 carbon atoms, preferably 14 to 20, and more preferably 16 to 18 carbon atoms, can be prepared by a reductive amination reaction to produce an unsaturated monoamine, and this unsaturated monoamine can be dimerized. Alternatively, the above unsaturated fatty acid or its ester, a higher unsaturated nitrile, or a higher unsaturated alcohol can be dimerized to obtain the corresponding polyhydric fatty acid, polyhydric nitrile, or polyhydric alcohol, and then a reductive amination reaction can be performed. This yields a dimer amine.

[0032] The polyimide constituting the polyimide film of the present invention is polymerized using an aromatic acid dianhydride having two carboxylic acid dianhydride groups in its molecule and a diamine having two amino groups in its molecule as raw materials. Preferred diamines include aromatic diamines having at least one organic group represented by general formula (2).

[0033] [ka]

[0034] Examples of preferred aromatic diamines constituting the polyimide film of the present invention include 2,2-bis(4-aminophenoxyphenyl)propane (BAPP), 1,3-bis(3-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), bis[4-(aminophenoxy)phenyl]sulfone (BAPS), bis[4-(3-aminophenoxy)phenyl]sulfone (M-BAPS), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HF-BAPP), 4,4'-bis(4-aminophenoxy)diphenyl sulfide, 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), and 4,4-bis(3-aminophenoxy)biphenyl (M-BAPB).

[0035] Preferred aromatic acid dianhydrides include aromatic carboxylic acid dianhydrides having at least one organic group represented by general formula (2). [ka] (In the formula, X represents the groups O, S, SO2, C(CF3)2, or C(CH3)2.)

[0036] Preferred aromatic acid dianhydrides used as raw materials for polyimide include, for example, 3,3',4,4'-diphenyl ether tetracarboxylic acid dianhydride (ODPA), 4,4'-(4,4'-isopropylidene diphenoxy) diphthalic acid dianhydride (BPADA), 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropanoic acid dianhydride (6FDA), 4,4'-bis(3,4-dicarboxyphenoxy)benzeneic acid dianhydride (HQDPA), 3,4'-oxydiphthalic acid anhydride (α-ODPA), and 2,3,4,4-diphenyl sulfone tetracarboxylic acid dianhydride (DSDA).

[0037] When the total amount of acid dianhydrides and diamines constituting the polyimide is set to 100 mol%, the total ratio of aromatic acid dianhydrides and aromatic diamines containing the organic group shown in formula (2) is preferably 30 mol% or more, more preferably 35 mol% or more, and even more preferably 40 mol% or more. In addition to the aromatic acid dianhydrides and aromatic diamines, acid dianhydrides and diamines that do not contain the organic group shown in formula (2) may also be used, but their total ratio is preferably 40 mol% or less, more preferably 30 mol% or less.

[0038] By using a polyimide polymerized with one or both of an aromatic acid dianhydride and an aromatic diamine having at least one organic group represented by the general formula (2) above, a polyimide film without a yield point in the stress-strain curve obtained by tensile testing can be suitably obtained.

[0039] The polyimide constituting the polyimide film of the present invention is produced by polymerizing equimolar amounts of a diamine and an aromatic dianhydride. For example, it can be obtained by polymerizing a diamine and an aromatic dianhydride in a polar organic solvent using a molar ratio of 0.9 to 1.1. Specifically, a polyimide precursor is obtained by dissolving a diamine in an aprotic polar solvent under a nitrogen atmosphere, then adding an acidic dianhydride, and reacting at room temperature for about 1 to 20 hours. To accelerate the reaction, the mixture may be heated to a temperature of 40°C to 80°C. Alternatively, a polyimide solution can be obtained by heating to a temperature of 150°C to 200°C to induce a ring-closing reaction.

[0040] Examples of aprotic polar solvents used in polymerization include amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, as well as polar solvents such as 2-butanone, diglyme, and γ-butyrolactone. Mixtures thereof can also be used. In some cases, xylene, hexane, etc., can be added to improve solubility.

[0041] The preferred molecular weight range for polyimide precursors and polyimide solutions is preferably 15,000 to 250,000 in number-average molecular weight and 30,000 to 800,000 in weight-average molecular weight. However, this does not mean that all polyimide precursors outside this range cannot be used. The preferred molecular weight of the polyimide used in this invention is within the same range as the preferred molecular weight range for the polyimide precursor and polyimide solution described above. The molecular weight can be measured by gel permeation chromatography (GPC).

[0042] The polyimide precursor has a structure in which the diamine and acidic dianhydride do not completely form imide bonds, but rather remain partially bound by amide bonds. The molecular ends of the polyimide precursor may be capped with aromatic monoamines or aromatic monocarboxylic acids.

[0043] The polyimide used in this invention is obtained by dehydrating the polyimide precursor to completely imidize it. Imidization can be carried out by chemical imidization or thermal imidization. Chemical imidation involves adding a dehydrating agent and a catalyst to a solution of polyimide precursor and carrying out a chemical dehydration reaction at 30°C to 60°C. Typical dehydrating agents include acetic anhydride, and pyridine is used as a reaction catalyst. Thermal imidation is performed by heat-treating a solution of polyimide precursor at a temperature of approximately 180°C to 360°C for 10 minutes to 20 hours. The heat treatment temperature can be adjusted within this range depending on the required mechanical properties. Thermal imidation is a relatively quick process; the imidation reaction can be completed in a relatively short time. It is even possible to perform the process with a heat treatment of 60 minutes or less, including preheating to remove the solvent.

[0044] The polyimide film of the present invention is obtained by applying the above-mentioned polyimide precursor or polyimide solution onto any support substrate such as glass, metal, or resin, and then heat-treating it. When using a polyimide precursor solution, the process can be carried out by heating the solution at a temperature of 150°C or lower for 2 minutes to 60 minutes to remove the solvent, and then heat-treating it at a temperature of approximately 180°C to 360°C for 10 minutes to 20 hours to perform thermal imidization. When using a polyimide solution, the solvent can be removed by heating the solution at a temperature of 180°C or lower for 2 to 60 minutes.

[0045] The polyimide film of the present invention may contain other optional components in an amount of 10% by weight or less, depending on the desired physical properties. Examples of other optional components include polyimides other than the polyimide of the present invention, organic fillers, and inorganic fillers.

[0046] The polyimide film of the present invention is a heat-resistant film that can be easily stretched with little force. Therefore, the polyimide film of the present invention can also be used as a laminate and is suitable for use in wearable devices.

[0047] Specifically, a laminated device can be fabricated by laminating a conductive layer on one or both sides of the polyimide film of the present invention and laminating semiconductor components on the conductive layer. Examples of laminated devices include LED light-emitting materials, antennas, and sensor devices.

[0048] The polyimide film of the present invention has the characteristic of being resistant to decomposition even when heated at high temperatures, and in particular, its 5% weight loss temperature (Td5) can be set to 350°C or higher. Therefore, it is resistant to decomposition even in thermal processing steps in the manufacturing of semiconductor components, such as heat reflow processing of silicon wafers. By utilizing the high-temperature decomposition resistance, a silicon wafer fixing adhesive layer is provided on one side of the polyimide film of the present invention, thereby obtaining a silicon wafer fixing film that can be suitably used in semiconductor component manufacturing.

[0049] In other words, one form of utilization of the polyimide film of the present invention is a method for manufacturing a semiconductor component, which sequentially includes a fixing step of using the polyimide film of the present invention as a substrate, providing an adhesive layer on one side thereof, attaching and fixing a silicon wafer onto the adhesive layer, a processing step of processing the silicon wafer, a dicing step of cutting the silicon wafer attached to the substrate to obtain a semiconductor chip, and a pick-up step of peeling the substrate off the semiconductor chip.

[0050] In the semiconductor component manufacturing method described above, the fixing step involves using the polyimide film of the present invention as a substrate, providing an adhesive layer on one side thereof, and detachably attaching and fixing a silicon wafer to the adhesive layer on the substrate. The adhesive layer is formed by applying an adhesive to one side of the polyimide film. A heat-resistant resin is used as the adhesive, for example, epoxy resin or acrylic resin can be used. The processing step involves processing the silicon wafer in a high-temperature environment using the substrate to which the silicon wafer is attached via the adhesive layer. The ambient temperature for the processing step is, for example, 350°C. The polyimide film of the present invention, which serves as the substrate, hardly deteriorates even in such a high-temperature environment.

[0051] The dicing process is the process of cutting the silicon wafer, along with the substrate, after the processing process to obtain a semiconductor chip. The pickup process is the process of peeling and obtaining the semiconductor chip from the substrate to which it is attached after the dicing process. By performing these processes in order, a processed semiconductor chip can be manufactured. Other processes may be added between and before / after each process. [Examples]

[0052] The present invention will be described in detail below based on examples, but the invention is not limited to these examples. The measurement and evaluation of various physical properties are as follows.

[0053] [Measurement of number-average molecular weight (Mn) and weight-average molecular weight (Mw)] The molecular weight distribution of polyimide was measured in the synthesized polyimide solution using gel permeation chromatography (Tosoh Corporation, product name: HLC-8220GPC). Polystyrene was used as the standard substance, and N,N-dimethylacetamide was used as the developing solvent.

[0054] [Measuring film thickness] The thickness of the polyimide film used for the physical property test was measured using a micrometer.

[0055] [Measurement of elongation at fracture, strength at fracture, stress at 100% elongation, and stress at 200% elongation] A polyimide film sample (thickness A (mm) x width 10 mm x length 110 mm before testing) was subjected to a tensile test using a Strograph VG1F tensile testing machine (manufactured by Toyo Seiki Co., Ltd.). The initial tensile chuck distance was set to 40 mm, the tensile speed to 10 mm / min, and the film was stretched until it broke at a measurement temperature of 25°C.

[0056] For the tensile test of the aforementioned sample, the load F (N) applied to the sample when the distance between chucks was L mm was read, and the elongation ε (%) and stress δ (MPa) were calculated from the following formula. Elongation: ε=((L-40) / 40)×100 Stress: δ=F / (A×10)

[0057] Of the data obtained from the above tensile tests, the elongation ε at the time of film breakage was defined as the elongation at the break point (%), and the stress δ was defined as the strength at the break point. Furthermore, the stress δ when elongation ε = 100% was defined as the stress at 100% elongation, and the stress δ when elongation ε = 200% was defined as the stress at 200% elongation.

[0058] [Checking for the presence or absence of a yield point] The presence or absence of a yield point was determined from the stress-strain curve of the polyimide film obtained by the above tensile test. When the film was stretched and the strain of the film was increased, if the phenomenon of stress decreasing as the strain increased, as shown in the upper curve of Figure 1, was observed, it was determined that a yield point was present. If the phenomenon of stress decreasing as the strain increased, as shown in the lower curve of Figure 1, was not observed, it was determined that there was no yield point.

[0059] [Measurement of total light transmittance (TT)] The total light transmittance (TT) of a polyimide film (50mm x 50mm) was measured using a turbidimeter (HAZE METER NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

[0060] [Measurement of pyrolysis temperature (Td5)] Under a nitrogen atmosphere, a polyimide film weighing 10-20 mg was heated from 30°C to 450°C at a constant heating rate of 10°C per minute using a thermogravimetric analyzer (Hitachi High-Tech Science Corporation, TG / DTA7220). The weight loss was measured, and the temperature at which the weight loss rate of the polyimide film was 5% (based on the weight at 200°C) was defined as the thermal decomposition temperature (Td5).

[0061] Synthesis Example 1 Under a nitrogen atmosphere, equal amounts of N-methyl-2-pyrrolidone (NMP) and xylene were added as solvents to a 1000 ml separable flask. The diamine mixture and tetracarboxylic anhydride shown in Table 1 were added as diamine and acid anhydride components and dissolved. The total concentration of the diamine and acid anhydride components in the solution was 30% by weight. The solution was then heated to 190°C and heated and stirred for 5 hours to obtain a polyimide solution containing polyimide A with a number-average molecular weight (Mn) of 40,069 and a weight-average molecular weight (Mw) of 88,074.

[0062] In Table 1, the diamine content is the percentage (mol%) of the diamine in the total diamine components, and corresponds to the diamine component and its proportion (mol%) relative to the structural units derived from the diamine constituting the polyimide. Similarly, the acid anhydride content is the percentage (mol%) of the acid anhydride in the total acid anhydride components, and corresponds to the tetracarboxylic acid anhydride component and its proportion (mol%) relative to the structural units derived from the aromatic acid dianhydrides constituting the polyimide.

[0063] Synthesis Example 2 The diamine component was changed to the diamine mixture shown in Table 1, and polymerization was carried out in the same manner as in Synthesis Example 1 to prepare a polyimide solution containing polyimide B. Polyimide B had a number-average molecular weight (Mn) of 45,236 and a weight-average molecular weight (Mw) of 71,166.

[0064] Synthesis Example 3 The diamine component was changed to a diamine mixture in the proportions shown in Table 1, and polymerization was carried out in the same manner as in Synthesis Example 1 to prepare a polyimide solution containing polyimide C. Polyimide C had a number-average molecular weight (Mn) of 40,560 and a weight-average molecular weight (Mw) of 79,232.

[0065] Synthesis Example 4 The diamine and acid anhydride components were replaced with the tetracarboxylic anhydride and diamine mixture shown in Table 1, and polymerization was carried out in the same manner as in Synthesis Example 1 to prepare a polyimide solution containing polyimide D. Polyimide D had a number average molecular weight (Mn) of 45,929 and a weight average molecular weight (Mw) of 168,071.

[0066] Synthesis Example 5 Under a nitrogen atmosphere, N-methyl-2-pyrrolidone (NMP) was added as a solvent to a 1000 ml separable flask. The diamine mixture and tetracarboxylic anhydride shown in Table 1 were added as diamine and acid anhydride components and dissolved. The total concentration of the diamine and acid anhydride components in the solution was 20% by weight. The solution was then stirred at room temperature for 3 days to obtain a polyimide precursor solution with a number-average molecular weight (Mn) of 28,042 and a weight-average molecular weight (Mw) of 52,159.

[0067] Table 1 shows the chemical composition of each polyimide prepared in Synthesis Examples 1-5. The abbreviations used for diamines and acidic dianhydrides in Table 1 refer to the following compounds. BAPP: 2,2-bis(4-aminophenoxyphenyl)propane APB: 1,3-Bis(3-aminophenoxy)benzene TFMB: 2,2'-Bis(trifluoromethyl)-4,4'-diaminobiphenyl PSX-A: A diaminosiloxane (number average molecular weight 740) with an amine equivalent of 370 g / mol, represented by the following formula (3) (where m is in the range of 1 to 20). BY16-871: Diaminopropyltetramethyldisiloxane (manufactured by Toray Dow Corning) in an amine equivalent of 125 g / mol, represented by the following formula (3) (where p=1) (number average molecular weight 250) [ka] BTDA:1,2,4,5-benzenetetracarboxylic acid dianhydride ODPA: 3,3',4,4'-diphenyl ether tetracarboxylic acid dianhydride PMDA: Pyromelit acid dianhydride 6FDA: 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride

[0068] [Table 1]

[0069] Example 1 A solution of polyimide A was uniformly applied to a release film, and then the solvent was removed by heating and drying. After that, the release film was peeled off to obtain a polyimide film with a thickness of 33 μm.

[0070] Examples 2 and 3 Polyimide films with thicknesses of 30 μm and 33 μm were obtained from the solutions of polyimide B and C in the same manner as in Example 1.

[0071] Comparative Examples 1 and 2 Polyimide films with thicknesses of 34 μm and 11 μm were obtained from the solutions of polyimide D and E in the same manner as in Example 1.

[0072] Table 2 shows the physical properties measured for each polyimide film prepared in Examples 1-3 and Comparative Examples 1 and 2.

[0073] [Table 2] [Industrial applicability]

[0074] The polyimide film of the present invention can be used as a laminated device for wearable devices, substrates for FHE sensors, or devices consisting of 3D-shaped devices. Furthermore, since the polyimide film of the present invention is resistant to decomposition even in high-temperature environments, it can be suitably used as a film for fixing silicon wafers in semiconductor component manufacturing.

Claims

1. A polyimide film comprising a polyimide containing structural units derived from aromatic dianhydrides and structural units derived from diamines, A polyimide film characterized by the absence of a yield point in the stress-strain curve obtained by tensile testing.

2. The polyimide film according to claim 1, wherein the elongation at break is 100% or more, and the stress at 100% elongation is 10 MPa or less.

3. The polyimide film according to claim 1, wherein the 5% weight loss temperature (Td5) is 350°C or higher.

4. The polyimide film according to claim 1, wherein the polyimide contains 25 mol% or more of structural units derived from siloxane, polyetherdiamine, or dimeramine.

5. The polyimide film according to claim 1, wherein the polyimide contains 25 mol% or more of structural units derived from a silicon-containing diamine represented by general formula (1) relative to the total amount of structural units derived from the diamine. 【Chemistry 1】 (In the formula, R １ and R ２ Each of these is independently a divalent aliphatic hydrocarbon group having 3 to 20 carbon atoms, and R ３ , R ４ , R ５ , R ６ , R 7 and R ８ Each of these is independently a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms or a monovalent aromatic group having 6 to 18 carbon atoms, where m is an integer greater than or equal to 0 and less than n, and n is an integer greater than or equal to 1.

6. The polyimide film according to claim 1, wherein the polyimide is a polyimide having at least one organic group represented by general formula (2). 【Chemistry 2】 (In the formula, X represents a group of O, S, SO ２ , C(CF ３ ), or C(CH ２ ), or C(CH ３ ).) ２ (represents a group.)

7. A laminated device comprising a polyimide film according to any one of claims 1 to 6, on which a conductive layer is laminated on one or both sides, and on which semiconductor components are laminated.

8. A device comprising a wearable device, a substrate for an FHE sensor, or a 3D-shaped device, including the laminated device described in claim 7.

9. A silicon wafer fixing film for semiconductor component manufacturing, comprising a polyimide film according to any one of claims 1 to 6, with an adhesive layer for fixing silicon wafers provided on one side.

10. A method for manufacturing a semiconductor component, comprising: a fixing step of using a polyimide film according to any one of claims 1 to 6 as a base material, providing an adhesive layer on one side thereof, and attaching and fixing a silicon wafer onto the adhesive layer; a processing step of processing the silicon wafer; a dicing step of cutting the silicon wafer attached to the base material to obtain a semiconductor chip; and a pick-up step of peeling the base material from the semiconductor chip.

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