JP4487981B2 - 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. Moreover, these positive-type thin films do not always satisfy the heat resistance, storage stability, pattern embedding 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 represented by methyl ethyl ketone and can be developed with an aqueous alkaline solution to give a negative pattern, and a method for producing the same.

  According to the present invention, two diamine compounds comprising 20 to 80 mol% of diaminopolysiloxane and 80 to 20 mol% of 4,4′-diamino-4 ″ -hydroxytriphenylmethane, or 20 to Copolymers of 3,4 '-(hexafluoroisopropylidene) diphthalic dianhydride with three kinds of diamine compounds in which 10-60 mol% of hydroxyl group-free aromatic or cycloaliphatic diamine is added to 70 mol% And a novel polyimide having a hydroxyl group content of 0.5 to 3 mol%. Such a polyimide comprises two diamines consisting of diaminopolysiloxane and 4,4′-diamino-4 ″ -hydroxytriphenylmethane. Compounds or these two diamine compounds plus three hydroxyl group-free aromatic or cycloaliphatic diamines and 4,4'- It is produced by reacting with (hexafluoroisopropylidene) diphthalic dianhydride to form a polyamic acid once, followed by a polyimide reaction.

  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 diaminopolysiloxane that is one component of the two or three diamine compounds that react with the carboxylic acid 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, Nippon Unicar products F2-053-01, etc. can be used.

  In addition, the hydroxyl group-containing diamine that is 4,4′-diamino-4 ″ -hydroxytriphenylmethane is a repeating unit [after-mentioned (a) to (b) or (a) to (c)] is used in such a proportion that the hydroxyl group content is about 0.5 to 3.0%, preferably about 0.7 to 2.5%. On the other hand, when it is used at a higher ratio, it becomes too soluble in an alkaline aqueous solution.

  Further, examples of the hydroxyl group-free aromatic or alicyclic diamine include 3,3′-bis (aminophenyl) ether, 4,4′-bis (aminophenyl) ether, 1,3-bis (4-aminophenoxy). ) Such as benzene, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, etc. Aromatic diamines or alicyclic diamines such as 1,3-bis (aminomethyl) cyclohexane, 4,4′-bis (aminocyclohexyl) methane, 3,3′-bis (aminocyclohexyl) methane are used.

  When two types of diamine compounds are used, diaminopolysiloxane is about 20-80 mol%, preferably about 40-70 mol%, and 4,4′-diamino-4 ″ -hydroxytriphenylmethane is about 20 When the proportion of diaminopolysiloxane is less than this, a film is not formed, whereas when it is used more than this, development with an aqueous alkali solution is performed. If the proportion of 4,4′-diamino-4 ″ -hydroxytriphenylmethane is less than this, the unexposed area cannot be dissolved in the alkaline aqueous solution, whereas if it is used more than this, the exposed area also becomes an alkaline aqueous solution. Although it dissolves, the difference in dissolution rate between the exposed part and the unexposed part becomes small.

  When three kinds of diamine compounds are used, diaminopolysiloxane is used in an amount of about 20 to 70 mol%, preferably about 30 to 50 mol%, and 4,4′-diamino-4 ″ -hydroxytriphenyl. Methane is about 20-70 mol%, preferably about 30-50 mol%, and hydroxyl group-free aromatic or cycloaliphatic diamine is about 10-60 mol%, preferably about 20-40 mol%. When a hydroxyl group-free aromatic or cycloaliphatic diamine is used in such a ratio, the transmittance of the polyimide formed from it increases in the ultraviolet region, and it is sufficiently photosensitive even for a thick film such as 50 μm. However, when it is used in a proportion higher than this, the solubility of polyimide in a general-purpose low-boiling organic solvent decreases.

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℃でカルボン酸無水物を滴下し、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。 Diamine compound mixture and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride

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, a carboxylic acid anhydride is dropped into a polar solvent solution of the diamine compound mixture at about 0 to 10 ° C., and then reacted at about 30 to 150 ° C., preferably about 50 to 100 ° C. for about 2 to 8 hours. Is done by.

  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.

Siloxane polyimide, which is a product of the polyimidation reaction, is considered to be a block copolymer having repeating units (a) and (b) represented by the following general formula when two types of diamine compounds are used. The weight average molecular weight Mw (measured by GPC; converted to polystyrene) is about 10000 to 50000, preferably about 15000 to 30000.

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 is considered that a block copolymer having a repeating unit (c) represented by the following general formula is formed, and its weight average molecular weight Mw is higher than that when two kinds of diamine compounds are used. Thus, it is about 10,000 to 10,000, preferably about 20,000 to 50,000.

  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 on an alkali-resistant substrate such as quartz glass plate or copper, and spin coating (about 500 to 2500 rpm, preferably about 500 to 1000 rpm for about 10 seconds) is performed to form a film. After forming a film having a thickness of about 25 to 50 μm, the solvent is removed by pre-baking at about 70 to 100 ° C., preferably about 80 to 90 ° C. for about 5 to 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. When the proportion of photoacid generator used is less than this, the FPC pattern partially dissolves in the alkaline aqueous solution and becomes thin. 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) 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride 133.2 dissolved in 462 g of N-methyl-2-pyrrolidone while cooling with ice and maintaining a temperature of about 0 to 10 ° C. After the completion of the dropwise addition, the mixture was heated to 50 ° C. and stirred for 3 hours, and then heated to 200 ° C. for a dehydration reaction for 3 hours After the completion of the reaction, the reaction mixture was poured into water, By reprecipitation of the product, a hydroxyl group-containing polyimide (hydroxyl group content: 0.86 mol%) was obtained.

  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 wt% tetramethylammonium hydroxide aqueous solution, the polyimide film through 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 489 g and the developer aqueous solution concentration were changed to 2.5% by weight, respectively, to obtain negative-type polyimide patterns having good patterning properties.The hydroxyl group content of the hydroxyl group-containing polyimide was 0.65 mol%. there were.

  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 benzophenonetetracarboxylic 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 acid dianhydride was used as the tetracarboxylic dianhydride, the resulting polyimide (hydroxyl group content 0.99 mol%) had a light transmittance of 0.3 or less in the ultraviolet region. And 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 3
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 79.2 g (0.09 mol) of siloxane (BY16-853U) was charged and cooled with ice to maintain a temperature of about 0 to 10 ° C. while maintaining 4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride 133.2 g (0.3 mol) was added as a powder, and then 400 g of N-methyl-2-pyrrolidone was added to dissolve the acid anhydride, which was then heated to 50 ° C., stirred for 3 hours, and then heated to 200 ° C. After the reaction, the reaction mixture was poured into water and the product was reprecipitated to obtain a hydroxyl group-containing polyimide (hydroxyl group content: 0.80 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 polyimide film through 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 4
In Example 3, 40.7 g (0.09 mol) of 4,4 ′-[bis (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 3. The hydroxyl group content of the hydroxyl group-containing polyimide was 0.74 mol%.

Example 5
In Example 3, 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 3. The hydroxyl group content of the hydroxyl group-containing polyimide was 0.77 mol%.

Example 6
In Example 3, 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 3. The hydroxyl group content of the hydroxyl group-containing polyimide was 0.93 mol%.

The hydroxyl group-containing polyimides obtained in Examples 3 to 6 have a weight average molecular weight Mw of about 30000 to 50000.

Claims (6)

  Two diamine compounds consisting of 20-80 mol% diaminopolysiloxane and 80-20 mol% 4,4'-diamino-4 "-hydroxytriphenylmethane and 4,4 '-(hexafluoroisopropylidene) diphthalic acid A polyimide comprising a copolymer with an anhydride and having a hydroxyl group content of 0.5 to 3 mol%.   3 kinds of diamine compounds consisting of 20 to 70 mol% of diaminopolysiloxane, 70 to 20 mol% of 4,4'-diamino-4 "-hydroxytriphenylmethane and 10 to 60 mol% of hydroxyl group-free aromatic diamine and 4 , 4 '-(Hexafluoroisopropylidene) diphthalic dianhydride, a polyimide having a hydroxyl group content of 0.5 to 3 mol%.   3 types of diamine compounds consisting of 20 to 70 mol% of diaminopolysiloxane, 70 to 20 mol% of 4,4′-diamino-4 ″ -hydroxytriphenylmethane and 10 to 60 mol% of hydroxyl group-free alicyclic diamine and 4 , 4 '-(Hexafluoroisopropylidene) diphthalic dianhydride, a polyimide having a hydroxyl group content of 0.5 to 3 mol%.   Two kinds of diamine compounds consisting of diaminopolysiloxane and 4,4'-diamino-4 "-hydroxytriphenylmethane are reacted with 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride, and then once polyamic acid The method for producing a polyimide according to claim 1, wherein a polyimide reaction is performed after the formation of the film.   Three diamine compounds consisting of diaminopolysiloxane, 4,4'-diamino-4 "-hydroxytriphenylmethane and a hydroxyl-free aromatic diamine and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride The method for producing a polyimide according to claim 2, wherein a polyamic acid is once formed and then subjected to a polyimide reaction. Three diamine compounds consisting of diaminopolysiloxane, 4,4'-diamino-4 "-hydroxytriphenylmethane and alicyclic diamine containing no hydroxyl group, and 4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride The method for producing a polyimide according to claim 3, wherein a polyamic acid is once formed and then subjected to a polyimide reaction.