JP2000103849A - Polyimide for electrodeposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrodepositable polyimide excellent in heat resistance and electric insulating properties and dispersible in water by reacting a tetracarboxylic dianhydride with a diamine component contg. 3,5-diaminobenzoic acid. SOLUTION: This polyimide has an acid value of 10-20 mmolKOH/100 g resin and pref, has a 10% thermal decomposition temp. of 250 deg.C or higher, an imidization degree of 85% or higher, and a wt. average mol.wt. of 10,000-100,000. The diamine component pref. contains 10-50 mol% diaminobenzoic acid. The tetracarboxylic dianhydride may be arom. or aliph. When a polyimide is formed from a tetracarboxylic dianhydride and an arom. diamine, it is necessary to select such a combination as to give a solvent-soluble polyimide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition polyimide which can be used as a material constituting a member of a wiring board, and more particularly to a composition of an electrodeposition polyimide which can be used as a material for an insulating layer of a multilayer printed circuit board. .

[0002]

2. Description of the Related Art Due to the rapid development of semiconductor technology, semiconductor packages have been reduced in size, the number of pins has been increased, the fine pitch has been increased.
The miniaturization of electronic components has rapidly progressed, and the era of so-called high-density mounting has entered. Along with this, circuit boards are also being made more multilayered and thinner from single-sided wiring to double-sided wiring.

At present, a subtractive method and an additive method are mainly used for forming a conductive pattern on a circuit board.

The subtractive method is typically a method of forming a hole in a copper-clad laminate, plating the inside and the surface of the hole with copper, and forming a pattern by photoetching. Although this subtractive method is technically highly complete and inexpensive, it is difficult to form a fine pattern due to restrictions such as the thickness of the copper foil.

On the other hand, in the additive method, typically, a catalyst for electroless plating is contained in a laminate, and a resist is formed on a portion other than a circuit pattern forming portion on the laminate,
This is a method in which a circuit pattern is formed on an exposed portion of the laminate by electroless copper plating or the like. Although the additive method can form a fine pattern, improvement is required in terms of cost and reliability.

In the case of a multi-layer circuit board, a method of laminating a single-sided or double-sided circuit board prepared by the above method together with a semi-cured prepreg in which a glass cloth is impregnated with an epoxy resin or the like is used. Have been. In this case, the prepreg serves as an adhesive for each layer, and the connection between the layers is made by forming through holes and applying electroless plating or the like to the inside.

Further, with the development of high-density mounting technology, a multilayer substrate is required to be thinner and lighter, and at the same time, to have a high wiring capacity per unit area. The method of mounting components has been devised.

However, the method of manufacturing a multilayer circuit board using a double-sided circuit board manufactured by the above-described subtractive method requires high precision in drilling for forming a hole in the double-sided circuit board and a limit of miniaturization. There is a limit to densification,
It was also difficult to reduce the manufacturing cost.

On the other hand, in recent years, a multilayer circuit board manufactured by sequentially laminating a conductive pattern layer and an insulating layer on a board has been developed to satisfy the above requirements. Since this multilayer circuit wiring board is manufactured by alternately performing photo-etching of the copper plating layer and patterning of the photosensitive resin, high-definition wiring and interlayer connection at an arbitrary position are possible.

However, in this method, since copper plating and photoetching are alternately performed a plurality of times, the process becomes complicated. In addition, if a trouble occurs in an intermediate process due to a series process of stacking one layer on a substrate, It has become difficult to regenerate this, which has hindered the reduction of manufacturing costs.

Further, in the conventional multilayer circuit board,
Since the connection between the layers was performed by forming via holes, a complicated photolithography step was required, which hindered a reduction in manufacturing cost.

On the other hand, as one method of forming an insulating layer on a circuit board, a desired conductive pattern proposed in JP-A-8-116172 is formed, and then a resin electrodeposition is performed on the conductive pattern. There is a method of forming an insulating pattern by forming an insulating resin layer by a method. Conventionally used resins for forming such an insulating pattern include epoxy resin, acrylic resin, urethane resin and the like.
However, the epoxy resin, acrylic resin, urethane resin, etc. used as the insulating resin do not simultaneously satisfy the characteristics such as electric insulation and heat resistance, and the formed insulating pattern is insufficient in characteristics. Was something.

On the other hand, polyimide resins have been conventionally known as having excellent insulating properties and heat resistance. However, usually, polyimide resins have low solvent solubility, and it has been difficult to obtain polyimides that can be dispersed in water.

[0014]

An object of the present invention is to solve such problems, and an object of the present invention is to provide an electrodepositing method which is excellent in heat resistance and electric insulation and can be dispersed in water. It is to provide a possible polyimide.

[0015]

Means for Solving the Problems The present inventors have found that the above-mentioned problems can be solved by including 3,5 diaminobenzoic acid in the raw material to make the acid value of the polyimide specific. Here, the polyimide of the present invention is a polyimide which is a reaction product of a tetracarboxylic dianhydride and a diamine, wherein at least a part of the diamine is 3,5 diaminobenzoic acid, and an acid of the polyimide. The value is 10 to 200 mmol KOH / 100 g re
It is characterized by being sin.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyimide of the present invention will be specifically described below.

Polyimide The polyimide of the present invention has an acid value of 10 to 200 mmolK.
OH / 100 g resin. When the acid value of the polyimide is 10 mmol / KOH or less, there is a problem in that when the electrodeposition coating material is prepared, dispersibility is poor and precipitation or the like is easily caused. On the other hand, when the acid value is 200 mmol / KOH or more, when a coating film is formed, there is a problem that water absorption is high, reliability is reduced under high temperature and high humidity, and electrodeposition property is lacking.

In the present invention, the soluble polyimide includes NMP, DMF, DMAc, γ-butyrolactone, D
It means those soluble in solvents such as MSO and sulfolane, preferably NMP. Such a soluble polyimide is capable of forming an electrodeposition paint.

Further, the polyimide of the present invention has a 10% thermal decomposition temperature, preferably 250 ° C. or higher, more preferably 3% or more.
The temperature is 50 ° C. or higher, particularly preferably 450 ° C. or higher. 1
Those having a high 0% thermal decomposition temperature are preferable from the viewpoint of improving the heat resistance of electronic members such as a multilayer substrate.

The imidation ratio of the polyimide of the present invention is preferably 85% or more, more preferably 90% or more, and particularly preferably 95% or more. 85% imidation rate
In the following, there is a problem that the residual amic acid promotes migration of metal ions, and the time-dependent change of the polyimide solution becomes large.

The weight average molecular weight of the polyimide of the present invention is 1
0000 to 100,000 is preferred. Particularly preferably 5
0000 to 80,000. When the molecular weight is 10,000 or less, it is difficult to obtain a uniform coating film, and when the molecular weight is 100,000 or more, gelation occurs.

The molecular weight is measured, for example, by using a high-speed G manufactured by Tosoh Corporation.
This can be performed by using a PC device. The column that can be used here is TSKge manufactured by Tosoh Corporation.
lαM, the solvent is DMF + 10 mmol phosphate buffer (P
H7.0) The flow rate is 0.5 cm / min.

The polyimide of the present invention contains a carboxyl group, and such a carboxyl group can be introduced in a required amount using diaminobenzoic acid or the like.
The amount of diaminobenzoic acid in the diamine is 10 to 50 mol%
Is preferred. If it is less than 10 mol%, the dispersibility deteriorates, and if it exceeds 50 mol%, the electrodeposition property deteriorates.

Tetracarboxylic dianhydride Examples of the acid dianhydride used in the synthesis of the polyimide of the present invention include, for example, 3,4,3 ′, 4′biphenyltetracarboxylic dianhydride 3,4 , 3 ', 4'Benzophenonetetracarboxylic dianhydride 2,3,3', 4'Biphenylethertetracarboxylic dianhydride 3,4,3 ', 4'Biphenylsulfonetetracarboxylic dianhydride (Carboxylphenyl) propane dianhydride 4,4 '-[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bis (1,2-benzenedicarboxylic dianhydride) (6FDA) bistrifluoromethyl Pyromellitic acid, bis (dicarboxyphenyl) sulfone dianhydride bis (dicarboxyphenyl) ether dianhydride thiophenetetracarboxylic acid dianhydride Hydrates Pyromellitic dianhydride 1,2,5,6-naphthalenetetracarboxylic dianhydride 2,3,5,6-Aromatic acid dianhydrides such as pyridinetetracarboxylic dianhydride 1,2,3 2,4-butanetetracarboxylic dianhydride cyclopentanetetracarboxylic dianhydride bicyclooctenetetracarboxylic acid bicyclo (2,2,2) -oct-7-ene-2,3
5,6-Tetracarboxylic dianhydride Aliphatic dianhydrides such as 5 (2,5-dioxotetrahydrofuryl) 3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride can be mentioned. These may be used alone or in combination of two or more. When an acid dianhydride and an aromatic diamine are selected to form a polyimide, it is necessary to select a combination in which these combinations are soluble in a solvent.

Examples of the aromatic diamines used in the polyimide of the diamine present invention, other 3,5-diaminobenzoic acid essential ingredients, for example, in particular 2, 4 (or 2,5) diaminotoluene 1, 4-benzenediamine 1,3-benzenediamine 6-methyl-1,3-benzenediamine 4,4'-diamino-3,3'-dimethyl-1,1'-
Biphenyl 4,4'-amino-3,3'-dimethoxy-1,1'-
Biphenyl 4,4'-methylenebis (benzeneamine) 4,4'-oxybis (benzeneamine) 3,4'-oxybis (benzeneamine) 3,3'-carboxynyl (benzeneamine) 4,4'-thiobis (benzeneamine 4,4'-sulfonyl (benzeneamine) 3,3'-sulfonyl (benzeneamine) 1-methylethylidine 4,4'-bis (benzeneamine) 3,3'-dichloro-4,4'-diaminobiphenyl 3,3'-dinitro-4,4'-diaminobiphenyl 3,3'-diaminobenzophenone 1,5-diaminonaphthalene 1-trifluoromethyl 2,2,2-trifluoroethylidine 4,4'-bis (benzene Amine) 1,1,1,3,3,3-hexafluoro-2-bis-
4 (4-aminophenyl) propane 4,4′-diaminobenzanilide 2,6-diaminopyridine 4,4′-diamino-3,3 ′, 5,5′-tetramethylbiphenyl 2,2bis (4 (4 -Aminophenoxy) phenyl) propane bis (4- (3-aminophenoxy) phenyl) sulfone bis (4- (4-aminophenoxy) phenyl) sulfone bis (4- (4-aminophenoxy) phenyl) ethyl 1,4- Bis (4-aminophenoxy) benzene 1,3 bis (3-aminophenoxy) benzene 9,9′-bis (4-aminophenyl) fluorene benzidine-3,3-dicarboxylic acid 4,4 ′-(or 3, 4'-, 3, 3'-, 2,
4′-) diamino-biphenyl ether diaminosilane compound and the like. These can be used alone or as a mixture of two or more polyimide compositions.However, when an acid dianhydride or an aromatic diamine is selected to form a polyimide, it is necessary to select a combination in which these combinations are solvent-soluble. .

Preferred Examples of Polyimides There are many polyimides formed from a combination of an acid dianhydride and an aromatic diamine as described above, but the polyimide of the present invention has at least a part of a diamine of 3,5.
Diaminobenzoic acid. Among these, preferred structural units include the following.

The following general formula:

[0028]

Embedded image (Where A ₁ is the following formula;

[0029]

Embedded image And B ₁ is a group represented by the following formula:

[0030]

Embedded image Is a group selected from A) polyimide, which is a copolymer comprising one or more structural units selected according to (1).

The following general formula:

[0032]

Embedded image (Wherein A ₂ has acid anhydride solubility,

[0033]

Embedded image B ₂ is a group selected from the same group as B ₁ , A ₃ is a group selected from the same group as A ₁ , B ₃ has a diamine solubility, formula,

[0034]

Embedded image Is a group selected from A polyimide comprising at least one structural unit selected from the group consisting of:

The following general formula:

[0036]

Embedded image (Where A ₄ is the same as A ₂ , B ₄ is a group selected from the same group as B ₁ , A ₅ is a group selected from the same group as A ₁ , B ₅ A group selected from the same group as ₃ ,
A polyimide comprising one or more structural units.

Method for Forming Polyimide Electrodeposition Solution Usually, polyimide is synthesized by a dehydration-condensation polymerization reaction of an acid dianhydride and a diamine.

[0038]

Embedded image The aromatic acid dianhydride and the aromatic diamine are used in approximately equivalent amounts, and are heated and dehydrated in an organic polar solvent to synthesize a solvent-soluble polyimide.

Examples of the organic polar solvent (hydrophilic solvent) usable here include N-methylpyrrolidone, N, N'-dimethylacetamide, N, N'-dimethylformamide, dimethylsulfoxide, tetramethylurea, tetrahydrourea Thiophene-1,1-oxide and the like. From the viewpoint of safety, N-methylpyrrolidone and 1-sulfolane are preferably used.

An electrodeposition paint can be formed by adding the above-mentioned organic polar solvent, neutralizing agent, hydrophobic solvent, ion-exchanged water, etc. to the polyimide resin varnish thus prepared.

The polar organic solvents to be added to the varnish include, for example, the above-mentioned ones, and several of them can be selected and mixed for use. The amount of the polar organic solvent is preferably from 20 to 80% based on the coating composition. When the amount is 20% or less, the dispersibility deteriorates, and when the amount is 80% or more, the electrodeposition property deteriorates.

Examples of the neutralizing agent include N-dimethylethanol, triethylamine, triethanolamine,
N-dimethylbenzylamine and N-methylmorpholine are exemplified. Of these, N-dimethylethanol and N-methylmorpholine are preferred. As the degree of neutralization,
It is preferably from 15% to 300% based on the carboxyl group.
If it is less than 15%, the dispersibility deteriorates. At 300% or more,
Electrodeposition property deteriorates.

Other components of the electrodeposition paint include a hydrophobic solvent. The effect of improving the coating film smoothness by the hydrophobic solvent and improving the stability of the paint is obtained. It is considered that the smoothness of the coating film is improved because the hydrophobic solvent generally has a high boiling point and remains in the coating film until a high temperature, so that the flowability of the coating film is improved. Although the improvement in paint stability is not necessarily clear, hydrophobic solvents generally have low affinity for water and high affinity for polyimide. And stabilizes the emulsion.

Examples of the hydrophobic solvent include benzyl alcohol, 2-phenylethyl alcohol, 4-methylbenzyl alcohol, 4-methoxybenzyl alcohol, 4-chlorobenzyl alcohol, 4-nitrobenzyl alcohol, phenoxy-2-ethanol, Cinnamyl alcohol, furfuryl alcohol, naphthyl carbinol and the like can be mentioned. These amounts are preferably 0.1 to 20% based on the paint. When the content is 0.1% or less, the effects of improving the smoothness of the coating film and the stability of the coating material are not exhibited, and when the content is 20% or more, the stability of the coating material is deteriorated.

In such a solvent, the polyimide resin is
The amount is adjusted by further adding ion-exchanged water so as to be in the range of 20% by weight. When the amount of the polyimide resin is 3% or less, the electrodeposition property deteriorates, and when the amount is 20% or more, the dispersibility deteriorates. I do.

[0046]

Example 1 (Synthesis of polyimide) Reflux cooling with a 1-liter three-neck separable flask equipped with a stainless steel squirrel stirrer, a nitrogen inlet tube, and a cooling tube with a ball on a trap with a stopcock. The vessel was attached. The separable flask was placed in a silicone bath equipped with a temperature controller and heated while flowing a nitrogen stream. The reaction temperature was indicated by bath temperature. 3,4,3
96.67 g of '4'-benzophenonetetracarboxylic dianhydride (hereinafter referred to as BTDA) (300 mmol)
l) 2.4 diaminotoluene (Mitsui Chemicals) 18.3
3 g (150 mmol), 3,4,3'4'-biphenyltetracarboxylic dianhydride (BPDA / Ube Industries, Ltd.) 44.13 g (150 mmol), 3,5 diaminobenzoic acid (DABz / Dainippon Ink) 22.8g
(150 mmol), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP / Wakayama Seika Co., Ltd. product) 64.98 g (158.3 mmol), maleic anhydride 1.63 g (15 .66 mmol) 15.3 g (150 mmol) of acetic anhydride was placed in a three-necked flask, and 918 g of NMP was added. The mixture was heated and stirred at 180 ° C. for 5 hours in a silicon bath while passing nitrogen through. A 20% NMP solution of polyimide was obtained. This was detected by high-performance liquid chromatography with ultraviolet rays, and the molecular weight in terms of polystyrene was measured. The acid value of the obtained polyimide is 60 mmol KOH / 100 g res.
was in. Number average molecular weight Mn = 22600, weight average molecular weight Mw = 40100, Z average molecular weight Mz = 635
00Mw / Mn = 1.77.

(Formation of Polyimide Electrodeposition Solution) 150 g of 3SN (mixed solution of NMP: tetrahydrothiophene-1,1-dioxide = 1: 3 (weight)), 100 g of 20% strength polyimide varnish, 75 g of benzyl alcohol, and methyl morpholine 5. 0 g (neutralization rate: 200%) and 30 g of water were stirred to prepare an aqueous electrodeposition solution. The obtained aqueous electrodeposition solution is
It was a 7.4% polyimide, pH 7.8, dark red-brown transparent liquid. The obtained electrodeposition liquid was excellent in repeated electrodeposition properties.

(Formation of Conductive Layer on Transfer Master) A degreased stainless steel plate having a thickness of 0.2 mm was prepared as a conductive substrate, and a commercially available plating photoresist (Tokyo Ohka Kogyo Co., Ltd.) was placed on this stainless steel plate. OMR85)
Is applied to a thickness of 1 μm and dried, and then subjected to contact exposure using three types of photomasks on which wiring patterns are formed, followed by development, washing, drying, and heat curing to transfer with an insulating layer. A master plate was prepared.

(Formation of resist) A resist “OMR-83” manufactured by Tokyo Ohka Co., Ltd.
Exposure was performed through a mask at an exposure amount of 60 mj, and development was performed using a specified developer. Post bake on hot plate at 145 ° C
For 30 minutes.

(Formation of metal wiring) Copper sulfate plating 10 μm was formed. The conditions are as follows.

Liquid composition of electrolytic copper plating Copper sulfate (pentahydrate) 75 g / l, sulfuric acid 190 g / l, chloride ion 60 mg / l Sulcap AC-90M 2.5 ml Temperature 30 ° C. Plating conditions Current density 2 A / dm ² , time 24 minutes

(Formation of Electrodeposition Layer) The prepared electrodeposition paint of the electrodeposition paint of Example 1 was put into a 2 liter glass cell, and stirred at a temperature of 25 ° C., a distance of 4 cm, and a voltage of 50 V with a stirrer. Electrodeposition was performed while changing the time to obtain a coating film having a wet film thickness of 30 μm. 150 ° C on a hot plate,
After drying for 3 minutes, a dry film thickness of 20 μm was obtained.

(Transfer, Peeling) SUS3 as a transfer destination substrate
Using the substrate No. 04, thermal transfer was performed on the substrate at 200 ° C. for 1 minute at 1 kg / cm ² . Thereafter, the temperature was returned to normal temperature, and the plate substrate was peeled off.

(Heat treatment (curing)) Thermal curing was performed at 250 ° C. for 1 hour in a nitrogen atmosphere. In the wiring pattern obtained through the above steps, a pattern having a line width of 30 μm or more was formed uniformly.

A wiring pattern was formed using the polyimide resin electrodeposition solution of Example 1, and a DC voltage of 30 V was applied under an atmosphere of 85 ° C. and 85% RH, and the film thickness capable of retaining insulation was examined. The polyimide resin had a film thickness of 3 μm and was able to maintain insulation.

FIG. 1 is a graph showing the results of measuring the insulation properties of polyimide resin wiring under high temperature and high humidity in Example 1. Even if the thickness is as thin as 3 μm,
It was confirmed that high resistance was maintained even after 300 hours.

Comparative Example 1 The procedure of Example 1 was repeated except that the epoxy electrodeposition solution prepared as described below was used instead of the polyimide electrodeposition solution. (Preparation of Epoxy Resin (Resin I) Electrodeposition Solution)
Diglycidyl ether of epoxy resin A (epoxy equivalent 910) 1
000 parts by weight were dissolved in 463 parts by weight of ethylene glycol monoethyl ether while maintaining the temperature at 70 ° C. with stirring.
Further, 80.3 parts by weight of diethylamine was added, and
For 2 hours to prepare an amine epoxy adduct (A).

On the other hand, Colonate L (Liisocyanate manufactured by Nippon Polyurethane Co., Ltd .; NCO 13% non-volatile content 7%)
5 wt%) 875 parts by weight of dibutyltin laurate 0.0
Add 5 parts by weight and heat to 50 ° C. to give 2-ethylhexano-
Then, 390 parts by weight of toluene was added, and the mixture was reacted at 120 ° C. for 90 minutes. Component (B) obtained by diluting the obtained reaction product with 130 parts by weight of ethylene glycol monoethyl ether.
I got

A mixture of 1000 parts by weight of the component A and 400 parts by weight of the component B was neutralized with 30 parts by weight of glacial acetic acid.
Dilute with 570 parts by weight of deionized water to obtain a nonvolatile content of 50 parts.
% By weight of resin I was prepared.

200.2 parts by weight of resin I (resin component 86.
33.3%), 583.3 parts by weight of deionized water and 2.4 parts by weight of dibutyltin laurate were mixed together to prepare an epoxy electrodeposition solution A.
Was prepared.

A wiring pattern was formed using the epoxy resin electrodeposition solution of Comparative Example 1, and a DC voltage of 30 V was applied in an atmosphere of 85 ° C. and 85% RH, and the film thickness capable of retaining insulation was examined. The epoxy resin needed a film thickness of 10 μm or more.

FIG. 2 is a graph showing the results of measuring the insulation properties of the epoxy resin wiring under high temperature and high humidity in Comparative Example 1. Even with a relatively thick film having a thickness of 30 μm, a large decrease in the resistance value is observed.
It can be seen that the resistance value decreases with the passage of time even if the thickness is μm.

Comparative Example 2 A polyimide was prepared by using diaminotoluene instead of diaminobenzoic acid in Example 1. This polyimide did not have water dispersibility, and an electrodeposition solution could not be prepared.

[0064]

According to the present invention, it is possible to obtain an electrodepositable polyimide which is excellent in heat resistance and electric insulation and can be dispersed in water.

[Brief description of the drawings]

FIG. 1 is a graph showing a measurement result of an insulation measurement result of a polyimide resin wiring under high temperature and high humidity in an example of the present invention (Example 1).

FIG. 2 is a graph showing a measurement result of an insulation measurement result of an epoxy resin wiring under high temperature and high humidity in Comparative Example 1.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kensaburo Kawago 1-1-1, Ichigaya-Kaga-cho, Shinjuku-ku, Tokyo F-term in Dai Nippon Printing Co., Ltd. (reference) 4J002 CM041 DE026 EC018 ED028 ED058 EJ008 EL068 EN029 EN109 EP017 ES008 ET017 EU027 EU239 EV207 GH01 HA06 4J038 DJ021 HA156 KA06 MA14 PA04 PB09 4J043 PA04 PA09 PC015 PC016 PC135 PC136 PC145 PC146 QB15 QB26 QB31 RA35 SA06 SA42 SA43 SA44 SA52 SA53 SA54 SA62 SA72 SB03 SB04 TA21 TA01 UA TA71 UA1 TA47 UA131 UA132 UA141 UA151 UA262 UA361 UA622 UA632 UA652 UA662 UA672 UA712 UB011 UB012 UB021 UB061 UB062 UB121 UB122 UB131 UB152 UB271 UB282 UB301 UB302 UB311 UB401 UB402 VA011 VA021 Z0221

Claims (7)

[Claims] 1. A polyimide which is a reaction product of a tetracarboxylic dianhydride and a diamine, wherein at least a part of the diamine is 3,5 diaminobenzoic acid and the polyimide has an acid value of 10 or less. ~ 200 mmol KOH
/ 100g resin, electrodeposition polyimide. 2. The polyimide has the following general formula: Wherein A ₁ is the following formula: And B ₁ is a group represented by the following formula: And 15 ≦ L ≦ 200. 2. The polyimide according to claim 1, which is a copolymer comprising one or more structural units represented by the formula: 3. The polyimide represented by the following general formula: (Wherein A ₂ has acid anhydride solubility, the following formula: B ₂ is a group selected from the same group as B ₁ , A ₃ is a group selected from the same group as A ₁ , B ₃ has a diamine solubility, The formula: And 15 ≦ L ≦ 200, and 15
≦ M ≦ 200. 2. The polyimide according to claim 1, comprising one or more structural units represented by: 4. The polyimide of the following general formula: (Where A ₄ is the same as A ₂ , B ₄ is a group selected from the same group as B ₁ , A ₅ is a group selected from the same group as A ₁ , B ₅ A group selected from the same group as ₃ ,
15 ≦ L ≦ 200 and 15 ≦ M ≦ 200. )
The polyimide according to claim 1, comprising one or more structural units represented by the following formula: 5. The polyimide according to claim 1, wherein a thermal decomposition temperature is 250 ° C. or higher. 6. A weight average molecular weight of 10,000 to 1,000.
The polyimide according to claim 1, wherein the number is 00. 7. An electrodeposition paint comprising the polyimide resin according to claim 1, water, a hydrophilic solvent, a hydrophobic solvent and a neutralizing agent.