JP4811158B2 - Polyimide and process for producing the same - Google Patents

Description

  The present invention relates to a polyimide and a method for producing the same. More specifically, the present invention relates to a polyimide that can be developed with an alkaline aqueous solution to give a negative pattern and a method for producing the same.

  Conventionally used photosensitive resins are polyester acrylate, epoxy acrylate, and the like, and an organic solvent is used as a developer in order to obtain a desired pattern after exposing these photosensitive resins. In such an organic solvent developing type photosensitive resin, in addition to safety and health problems during work due to the use of an organic solvent, adverse effects on the environment are becoming serious problems.

  In place of the organic solvent developing type photosensitive resin having such a problem, photosensitive resins capable of alkali development using novolak resin, polyvinylphenol, etc. are known, but most of them have a film thickness of several μm. It is used as a positive type thin film. In addition, these positive-type thin films do not always satisfy the heat resistance, storage stability, pattern embedding and the like required for FPC (flexible printed circuit board) applications.

In addition, since the polyimide resin itself is insoluble in an organic solvent, a method of once forming an organic solvent-soluble polyamic acid and then forming a polyimide is employed. There are cases where the polyimide resin itself is soluble in an organic solvent. For example, the polyamideimide resins described in Patent Documents 1 and 2 below are considered to be soluble in an organic solvent and have photosensitivity. However, the organic solvent here is an aprotic polar solvent such as dimethylformamide, and acetone, benzene, cyclohexanol, etc. are used for precipitation of the resin, that is, these organic solvents. Is insoluble.
JP-A-57-13127 JP 59-145216 A

  An object of the present invention is to provide a polyimide which is itself soluble in a general-purpose low-boiling organic solvent typified by methyl ethyl ketone and can be developed with an aqueous alkaline solution to give a negative polyimide, and a method for producing the same.

According to the invention, (A) 20-80 mol% diaminopolysiloxane and (B) 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4 Two kinds of diamine compounds consisting of 80 to 20 mol% of hydroxyl group-containing diamine which is ′ -diamino-3,3′-dihydroxytriphenylmethane, or 20 to 70 of each of these two kinds of diamine compounds (A) and (B) 3% diamine compound and 2,5-dioxotetrahydrofuryl group added to 10% by mole of (C) a specific hydroxyl group-free aromatic diamine or hydroxyl group-free alicyclic diamine. A novel polyimide comprising a copolymer with a tetracarboxylic dianhydride as an acid anhydride group and having a hydroxyl group content of 0.5 to 3 mol% is provided as (A) diaminopolysiloxane. And (B) 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4′-diamino-3,3′-dihydroxytriphenylmethane 2 types of diamine compounds composed of hydroxyl group-containing diamines or these two types of diamine compounds (A) and (B) and (C) a specific hydroxyl group-free aromatic diamine or hydroxyl group-containing alicyclic diamine, and 3 It is produced by reacting various diamine compounds with tetracarboxylic dianhydride having 2,5-dioxotetrahydrofuryl group as one acid anhydride group, once forming polyamic acid and then polyimidizing it. The

  According to the present invention, a polyimide that is soluble in a general-purpose low-boiling organic solvent is provided, and a photosensitive composition to which a photocrosslinking agent and a photoacid generator are added can be developed with an alkaline aqueous solution and has excellent patterning properties. A negative-type polyimide pattern is formed. When a hydroxyl group-free aromatic or alicyclic diamine is used in combination as the diamine compound, sufficient photosensitivity is exhibited even for a thicker film. In particular, when a hydroxyl group-free alicyclic diamine is used, the light transmittance is good, and a film having a thickness of, for example, 70 μm exhibits sufficient photosensitivity.

R：炭素数2〜6、好ましくは3〜5の2価の炭化水素基
R₁〜R₄：炭素数1〜5の低級アルキル基、フェニル基
n：0〜30の整数、好ましくは4〜12の整数 As the component (A) diaminopolysiloxane which is one component of the two or three diamine compounds that react with the carboxylic anhydride, compounds represented by the following general formula are used.

R: a divalent hydrocarbon group having 2 to 6 carbon atoms, preferably 3 to 5 carbon atoms
R _{1 to} R ₄ : lower alkyl group having 1 to 5 carbon atoms, phenyl group
n: an integer from 0 to 30, preferably an integer from 4 to 12

Examples of this compound include compounds in which R and R _{1 to} R ₄ are combinations of the following substituents.
R R ₁ R ₂ R ₃ R ₄
(CH ₂ ) ₃ CH ₃ CH ₃ CH ₃ CH ₃
(CH ₂ ) ₄ CH ₃ CH ₃ CH ₃ CH ₃
(CH ₂ ) ₃ CH ₃ C ₆ H ₅ CH ₃ C ₆ H ₅
pC ₆ H ₄ CH ₃ CH ₃ CH ₃ CH ₃

  Actually, commercially available products such as TOSHIBA silicone products TSL9386, TSL9346, TSL9306, Toray Dow Corning products BY16-853U, Shin-Etsu Chemical products X-22-161AS, Nihon Unicar products F2-053-01 and the like can be used.

The hydroxyl group-containing diamine as component (B) includes 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane, or 4,4′-diamino- 3,3'-dihydroxytriphenylmethane is used, and these hydroxyl group-containing diamines are those repeating units [the following (a) to (b) or (a ) ~ (c)] hydroxyl group content of about 0.5 to 3.0% in used in proportions such that preferably about 0.7 to 2.5%. When the hydroxyl group content is lower than this, dissolved in an aqueous alkali solution On the other hand, if it is used at a higher ratio, it becomes too soluble in an alkaline aqueous solution.

Further, the hydroxyl group-free aromatic diamine as component (C) includes 3,3′- bis (aminophenyl) ether, 4,4′-bis (aminophenyl) ether, 1,3-bis (4- Aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4'-diaminodiphenylsulfone or 3,3'-diaminodiphenylsulfone As the alicyclic diamine, for example, 1,3-bis (aminomethyl) cyclohexane, 4,4′-bis (aminocyclohexyl) methane, 3,3′-bis (aminocyclohexyl) methane, etc. are used. .

  When two types of diamine compounds (A) and (B) are used, diaminopolysiloxane (A) is used in an amount of about 20 to 80 mol%, preferably about 40 to 70 mol%, and 4,4'-diamino- The hydroxyl group-containing diamine (B), which is 4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4′-diamino-3,3′-dihydroxytriphenylmethane, is about 20 to When the proportion of diaminopolysiloxane (A) is less than this, no film is formed, whereas when it is used more than this, it is used depending on the alkaline aqueous solution. Development is impossible. With 4,4'-diamino-4 "-hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4'-diamino-3,3'-dihydroxytriphenylmethane A hydroxyl group-containing diamine When the ratio of (B) is less than this, the unexposed part cannot be dissolved in the alkaline aqueous solution, whereas when used more than this, the exposed part dissolves in the alkaline aqueous solution, but the dissolution rate between the exposed part and the unexposed part. The difference of becomes smaller.

  When three types of diamine compounds (A), (B), and (C) are used, diaminopolysiloxane (A) is about 20 to 70 mol%, preferably about 30 to 50 mol%. 4,4'-diamino-4 "-hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4'-diamino-3,3'-dihydroxytriphenylmethane containing hydroxyl groups The diamine (B) is about 20 to 70 mol%, preferably about 30 to 50 mol%, and the hydroxyl group-free aromatic or alicyclic diamine (C) is about 10 to 60 mol%, preferably about 20 to Each of them is used in a proportion of 40 mol% .When such a hydroxyl group-free aromatic or cycloaliphatic diamine (C) is used in such a proportion, the transmittance of the polyimide produced therefrom is increased in the ultraviolet region, for example, as thick as 50 μm. Shows sufficient photosensitivity to film However, when used in a more proportion of solubility in low-boiling organic solvent for the polyimide of the general-purpose is decreased.

との反応は、好ましくはジメチルホルムアミド、ジメチルアセトアミド、N-メチル-2-ピロリドン等の非プロトン性極性溶媒中で行われるが、この他にクレゾール、ピリジン等の極性溶媒中でも行われる。実際には、ジアミン化合物混合物の極性溶媒溶液中に、約0〜10℃でテトラカルボン酸二無水物を滴下し、その後約30〜150℃、好ましくは約50〜100℃で約2〜8時間反応させることによって行われる。2,5-ジオキソテトラヒドロフリル基を一方の酸無水物基とするテトラカルボン酸二無水物としては、他に5-(2,5-ジオキソテトラヒドロフリル)-3-シクロヘキセン-1,2-カルボン酸無水物、4-(2,5-ジオキソテトラヒドロフラン-3-イル)テトラリン-1,2-カルボン酸無水物等が用いられる。 Tetracarboxylic dianhydrides having a diamine compound mixture and a 2,5-dioxotetrahydrofuryl group as one acid anhydride group, such as 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene 1,2-carboxylic anhydride

The reaction with is preferably carried out in an aprotic polar solvent such as dimethylformamide, dimethylacetamide or N-methyl-2-pyrrolidone, but also in a polar solvent such as cresol or pyridine. In practice, tetracarboxylic dianhydride is dropped into a polar solvent solution of the diamine compound mixture at about 0 to 10 ° C., and then about 30 to 150 ° C., preferably about 50 to 100 ° C. for about 2 to 8 hours. This is done by reacting. Examples of tetracarboxylic dianhydrides having a 2,5-dioxotetrahydrofuryl group as one acid anhydride group include 5- (2,5-dioxotetrahydrofuryl) -3-cyclohexene-1,2- Carboxylic anhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) tetralin-1,2-carboxylic acid anhydride and the like are used.

  Since this reaction product is a polyamic acid which is a polyimide precursor, a dehydration reaction is performed to convert it into a polyimide. In the dehydration reaction, a polar organic solvent is further added as necessary to adjust the concentration to about 10 to 20% by weight, and then a dehydrating agent such as acetic anhydride or pyridine is used, preferably about 150 to 250 ° C., preferably The reaction is performed at about 180 to 200 ° C. for about 2 to 6 hours, preferably about 2 to 4 hours. At this time, it is also effective to azeotrope the produced water using toluene or the like.

Ar：5-(2,5-ジオキソテトラヒドロフリル)-3-メチル
-3-シクロヘキセン-1,2-カルボン酸残基 For example, when two types of diamine compounds in which the hydroxyl group-containing diamine is 4,4′-diamino-4 ″ -hydroxytriphenylmethane are used, the siloxane polyimide that is a product of the polyimidation reaction is as follows. also believed a block copolymer having a repeating unit represented by formula (a) and (b), (as measured by GPC; polystyrene equivalent) that these weight-average molecular weight Mw of about 10000 to 50000, preferably about 1 2 000 It is about ~ 30000.

Ar: 5- (2,5-dioxotetrahydrofuryl) -3-methyl
-3-Cyclohexene-1,2-carboxylic acid residue

Ar：5-(2,5-ジオキソテトラヒドロフリル)-3-メチル
-3-シクロヘキセン-1,2-カルボン酸残基 Further, for example, when three kinds of diamine compounds to which 4,4′-bis (aminophenyl) ether is added are used, in addition to the repeating units (a) and (b) represented by the above general formula, It believed that the block copolymer having a repeating unit (c) represented by the general formula: to produce a high molecular weight than that found that a weight average molecular weight Mw of 2 kinds of diamine compounds were used About 10,000 to 10,000, preferably about 20,000 to 50,000.

Ar: 5- (2,5-dioxotetrahydrofuryl) -3-methyl
-3-Cyclohexene-1,2-carboxylic acid residue

  The copolymer thus obtained is a low-boiling organic solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, ethylene glycol monomethyl ether, chloroform, or a non-volatile solvent such as dimethylformamide, dimethylacetamide, or N-methyl-2-pyrrolidone. Since it is soluble in a protic polar solvent, it is used as a solution dissolved in these organic solvents at a concentration of about 20 to 50% by weight, preferably about 30 to 45% by weight. By adding a photocrosslinking agent and a photoacid generator to such a solution, a photosensitive composition can be formed. By sensitizing such a photosensitive composition and developing it with an alkaline aqueous solution, Mold polyimide pattern is obtained.

That is, a solution-like photosensitive composition is dropped onto an alkali-resistant substrate such as a quartz glass plate and copper foil , and spin coating (about 500 to 2500 rpm, preferably about 500 to 1000 rpm for about 10 seconds) is performed. After forming a film with a film thickness of about 25-50 μm, the solvent is removed by pre-baking at about 70-100 ° C., preferably about 80-90 ° C. for about 5-10 minutes. A necessary mask is placed on the obtained photosensitive polyimide coating substrate, and ultraviolet rays are irradiated at an exposure dose of about 150 to 600 mJ / cm ² , preferably about 200 to 450 mJ / cm ² , and then about 110 to 140 ° C., preferably Post-exposure bake at about 120-135 ° C for about 5-10 minutes, and develop at about 30-50 ° C with an aqueous solution of an alkaline substance such as potassium hydroxide, sodium carbonate, tetramethylammonium hydroxide, etc. A clear negative pattern is obtained. The concentration of the developer used here is about 0.5 to 4% by weight, preferably about 0.5 to 3% by weight, and the development time is preferably within about 1 minute. After development, rinse with water and dry, then cure at 160 ° C for about 2 hours.

  Here, as the photocrosslinking agent, 2-hydroxymethyl-4,6-dimethylphenol, 1,3,5-trihydroxymethylbenzene, 3,5-dihydroxymethyl-4-methoxytoluene [2,6-bis ( A phenol-substituted product having a hydroxymethyl group such as hydroxymethyl) -p-cresol] is preferably used. These photocrosslinking agents are used in a ratio of about 1 to 50 parts by weight, preferably about 3 to 15 parts by weight, per 100 parts by weight of polyimide. When the proportion of the photocrosslinking agent used is less than this, the crosslinking density is insufficient and the polymer matrix is not sufficiently formed, so that the film is dissolved in the alkaline aqueous solution. The solubility is lowered and a crystal pattern is formed on the coated surface.

  Further, as the photoacid generator, nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, diphenyliodonium-9,8-dimethoxyanthracene-sulfonate, etc., about 1 to 50 parts by weight per 100 parts by weight of polyimide, Preferably it is used in a proportion of about 3 to 20 parts by weight. If the amount of photoacid generator used is less than this, the FPC pattern will be partially dissolved in the alkaline aqueous solution and become thinner, while if used in a proportion higher than this, it will be applied to the coated surface as in the case of the photocrosslinker. A crystal pattern is produced.

  Next, the present invention will be described with reference to examples.

Example 1
In a 1 L separable flask, 43.2 g (0.15 mol) of 4,4′-diamino-4 ″ -hydroxytriphenylmethane and 132 g (0.15 mol) of diaminopolysiloxane (Dow Corning product BY16-853U, amine equivalent 440) 5- (2,5-dioxotetrahydrofuryl) -3-methyl-dissolved in 380 g of N-methyl-2-pyrrolidone while cooling with ice and maintaining a temperature of about 0 to 0 ° C. 79.2 g (0.3 mol) of 3-cyclohexene-1,2-carboxylic acid anhydride was added dropwise, and after completion of the addition, the temperature was raised to 50 ° C., stirred for 3 hours, and then heated to 200 ° C. for dehydration reaction for 3 hours. After completion of the reaction, the reaction mixture was poured into water, and the product was reprecipitated to obtain a hydroxyl group-containing polyimide (hydroxyl group content: 1.05 mol%).

  To 100 parts (weight, the same applies hereinafter) of the obtained hydroxyl group-containing polyimide, 12.5 parts of 2,6-bis (hydroxymethyl) -p-cresol as a photocrosslinking agent and diphenyliodonium-9,10 as a photoacid generator 12.5 parts of -methoxyanthracene-2-sulfonate were added, and these were prepared as a mixed solvent solution of methyl ethyl ketone-ethylene glycol monomethyl ether (volume ratio 1: 1) having a solid content concentration of 40% by weight.

The prepared photosensitive polyimide solution was spin coated on the glossy surface of the copper foil under conditions of 600 rpm for 10 seconds, prebaked at 90 ° C. for 10 minutes to form a film with a thickness of 50 μm, and then there. A mask (Hitachi Chemical Product Photonics RP-1) was put on and exposed to 300 mJ / cm ² of ultraviolet light. Then, after post-exposure baking at 130 ° C. for 5 minutes, using a 2% by weight tetramethylammonium hydroxide aqueous solution, the polyimide film covered with the mask was developed at 40 ° C. for 60 seconds, then washed with water at room temperature for 1 minute, A negative polyimide pattern was obtained.

  When the obtained negative polyimide pattern was observed with an electron microscope, the pattern and the line width were 100 μm at 100/100 (μm), respectively, and it was confirmed that the pattern had excellent patternability. Further, no swelling was observed.

Example 2
In Example 1, the amount of 4,4′-diamino-4 ″ -hydroxytriphenylmethane was 34.8 g (0.12 mol), the amount of diaminopolysiloxane was 158.4 g (0.18 mol), and the amount of N-methyl-2-pyrrolidone Was changed to 410 g, and the concentration of the developer aqueous solution was changed to 2.5% by weight to obtain a negative-type polyimide pattern having good patterning properties.The hydroxyl group content of the hydroxyl group-containing polyimide was 0.97 mol%. Met.

Example 3
In Example 1, 34.5 g (0.15 mol) of bis (4-amino-3-hydroxyphenyl) methane was used in place of 4,4′-diamino-4 ″ -hydroxytriphenylmethane, and the exposure amount was 450 mJ / cm. ^The developer aqueous solution concentration was changed to 3% by weight, and the obtained negative polyimide pattern showed good patterning as in Example 1. The hydroxyl group of the hydroxyl group-containing polyimide was changed. The content was 2.17 mol%.

Example 4
In Example 1, 45.9 g (0.15 mol) of 4,4′-diamino-3,3′-dihydroxytriphenylmethane was used instead of 4,4′-diamino-4 ″ -hydroxytriphenylmethane, and similarly A negative polyimide pattern having good patterning properties was obtained, and the hydroxyl group content of the hydroxyl group-containing polyimide was 2.07 mol%.

  In addition, the hydroxyl group-containing polyimide obtained in each of the above examples has a weight average molecular weight Mw of about 12000 to 16000.

Comparative Example 1
In Example 1, when 96.6 g (0.3 mol) of benzophenone tetracarboxylic dianhydride was used as the tetracarboxylic dianhydride, the resulting polyimide (hydroxyl group content 0.98 mol%) was in the ultraviolet region, particularly at a wavelength of 350 Almost no light transmission was observed at ˜450 nm.

Comparative Example 2
In Example 1, when 93 g (0.3 mol%) of oxydiphthalic dianhydride was used as the tetracarboxylic dianhydride, the resulting polyimide (hydroxyl group content 0.99 mol%) had a light transmittance at 350 nm of 0.4 or less. It was inferior to that of Example 1. Further, the solubility of the photosensitive composition in the mixed solvent was only 20% by weight.

Example 5
In a 1 L separable flask, 34.8 g (0.12 mol) of 4,4′-diamino-4 ”-hydroxytriphenylmethane, 18.0 g (0.09 mol) of 4,4′-bis (aminophenyl) ether and diaminopolyethylene While charging 79.2 g (0.09 mol) of siloxane (BY16-853U) and cooling with ice to maintain a temperature of about 0 to 10 ° C., 5- (2,5-dioxotetrahydrofuryl) -3-cyclohexene- 79.2 g (0.3 mol) of 1,2-carboxylic acid anhydride was added as a powder, and then 300 g of N-methyl-2-pyrrolidone was added to dissolve the acid anhydride. After stirring for 3 hours, the mixture was dehydrated for 3 hours by raising the temperature to 200 ° C. After completion of the reaction, the reaction mixture was poured into water, and the product was reprecipitated to re-precipitate the hydroxyl group-containing polyimide (hydroxyl group content 1.10). Mol%).

  To 100 parts of the obtained hydroxyl group-containing polyimide, 12.5 parts of 2,6-bis (hydroxymethyl) -p-cresol and 12.5 parts of diphenyliodonium-9,10-methoxyanthracene-2-sulfonate were added, and these were added to a solid content. It was prepared as a mixed solvent solution of methyl ethyl ketone-ethylene glycol monomethyl ether (volume ratio 3: 7) having a concentration of 40% by weight.

The prepared photosensitive polyimide solution was spin-coated on the glossy surface of the copper foil at 500 rpm for 10 seconds, prebaked at 90 ° C. for 10 minutes to form a film with a thickness of 50 μm, and then there. A mask (Photonics PR-1) was put on and exposed to 300 mJ / cm ² of ultraviolet light. Then, after post-exposure baking at 120 ° C for 5 minutes, using a 2 wt% tetramethylammonium hydroxide aqueous solution, the masked polyimide film was developed at 40 ° C for 60 seconds, then washed with water at room temperature for 1 minute, A negative polyimide pattern was obtained.

  When the obtained negative polyimide pattern was observed with an electron microscope, the pattern and the line width were 100 μm at 100/100 (μm), respectively, and it was confirmed that the pattern had excellent patternability. Further, no swelling was observed.

Example 6
In Example 5, 40.7 g (0.09 mol) of bis [4- (3-aminophenoxy) phenyl] sulfone was used in place of 4,4′-bis (aminophenyl) ether. The obtained negative polyimide pattern showed good patterning as in Example 5. The hydroxyl group content of the hydroxyl group-containing polyimide was 0.91 mol%.

Example 7
In Example 5, 26.3 g (0.09 mol) of 1,3-bis (4-aminophenoxy) benzene was used in place of 4,4′-bis (aminophenyl) ether. The obtained negative polyimide pattern showed good patterning as in Example 5. The hydroxyl group content of the hydroxyl group-containing polyimide was 0.97 mol%.

Example 8
In Example 5, 12.8 g (0.09 mol) of 1,3-bis (aminomethyl) cyclohexane was used instead of 4,4′-bis (aminophenyl) ether. The obtained negative polyimide pattern showed good patterning as in Example 5. The hydroxyl group content of the hydroxyl group-containing polyimide was 1.4 mol%.

The hydroxyl group-containing polyimides obtained in Examples 5 to 8 have a weight average molecular weight Mw of about 30000 to 50000.

Claims (4)

(A) 20-80 mol% diaminopolysiloxane and (B) 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4′-diamino- Two diamine compounds consisting of 80 to 20 mol% of hydroxyl group-containing diamine, which is 3,3'-dihydroxytriphenylmethane, and a tetracarboxylic acid dicarboxylic acid containing 2,5-dioxotetrahydrofuryl group as one acid anhydride group A polyimide comprising a copolymer with an anhydride, having a weight average molecular weight Mw (GPC method, polystyrene conversion) of 10,000 to 50,000 and a hydroxyl group content of 0.5 to 3 mol%. (A) Diaminopolysiloxane 20 to 70 mol%, (B) 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4′-diamino- 20-70 mol% of hydroxyl group-containing diamine which is 3,3′-dihydroxytriphenylmethane and (C) 3,3′-bis (aminophenyl) ether, 4,4′-bis (aminophenyl) ether, 1, 3-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4′-diaminodiphenylsulfone or 3, 3'-Diaminodiphenylsulfone is a hydroxyl group-free aromatic diamine or a hydroxyl group-free alicyclic diamine. 10 kinds of diamine compounds consisting of 10 to 60 mol% and 2,5-dioxotetrahydrofuryl group are converted into one acid anhydride. Tet as a base A polyimide comprising a copolymer with lacarboxylic dianhydride, having a weight average molecular weight Mw (GPC method, polystyrene conversion) of 10,000 to 100,000 and a hydroxyl group content of 0.5 to 3 mol%.   (A) diaminopolysiloxane and (B) 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4′-diamino-3,3′- Two types of diamine compounds consisting of a hydroxyl group-containing diamine, which is dihydroxytriphenylmethane, and a tetracarboxylic dianhydride having a 2,5-dioxotetrahydrofuryl group as one acid anhydride group are reacted with each other to form a polyamic acid once. The method for producing a polyimide according to claim 1, wherein a polyimide reaction is performed after the formation of the film. (A) diaminopolysiloxane, (B) 4,4′-diamino-4 ″ -hydroxytriphenylmethane, bis (4-amino-3-hydroxyphenyl) methane or 4,4′-diamino-3,3′- Dihydroxytriphenylmethane, a hydroxyl group-containing diamine and (C) 3,3'-bis (aminophenyl) ether, 4,4'-bis (aminophenyl) ether, 1,3-bis (4-aminophenoxy) benzene A hydroxyl group which is bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4′-diaminodiphenylsulfone or 3,3′-diaminodiphenylsulfone consisting of free aromatic diamines or hydroxyl group-free alicyclic diamines three diamine compound and 2,5-dioxotetrahydrofuryl group anti tetracarboxylic dianhydride to one acid anhydride group It is allowed, once the preparation of the polyimide of claim 2, wherein the to polyimide reaction after forming a polyamic acid.