JPH04248871A - Paste of polyimide-based resin and ic using the same paste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new polyimide resin paste suitable as an overcoat material for screen printing and an IC using the same.

0002

2. Description of the Related Art Conventionally, resin pastes made of organic resins containing fine particles using epoxy resins, phenol resins, etc. are well known. However, since all of these resins have low heat resistance, the usable temperature of pastes made using these resins is about 300° C. at most. 300
Paste resins that can be used at temperatures above ℃ include:
aromatic polyimide resin, aromatic polyamideimide resin,
Heat-resistant resins such as aromatic polyamide resins are known.

However, in general, these high molecular weight heat-resistant resins have extremely poor solubility in solvents and it is difficult to make the solution highly concentrated, so the amount of solvent in the paste is large and it is difficult to impart thixotropic properties. In addition, pastes using these have disadvantages such as the paste tends to turn around the plate during screen printing and a thick film cannot be formed.

On the other hand, inorganic fine particles and organic resin fine particles have conventionally been used as fine particles. As the organic resin fine particles, polyimide resin fine particles are used for applications requiring a high degree of heat resistance. However, since these inorganic fine particles and polyimide resin fine particles are both insoluble in solvents, a large amount of these fine particles remain in the film obtained by heating the paste using them, so this film cannot be mechanically coated. The properties are significantly inferior. If the mechanical properties are not sufficient, cracks are likely to occur in the film, so semiconductor devices using such a film as the interlayer insulating film surface protection film lack reliability.

[0005]

[Problems to be Solved by the Invention] The present invention solves these problems and has thixotropic properties.
In particular, it can form a uniform thick film with few pinholes and voids.
The present invention provides a polyimide resin paste with excellent printability, film heat resistance, and mechanical properties, and an IC using the same.

[0006]

[Means for Solving the Problems] The present invention provides an aromatic tetracarboxylic acid half ester obtained by reacting an aromatic tetracarboxylic dianhydride and an alcohol with an aromatic diamine. Contains a molecular weight polyimide precursor, fine particles of heat-resistant resin, and a solvent. Before heat curing, the fine particles exist as a heterogeneous phase in contrast to a homogeneous phase consisting of the polyimide precursor and solvent, and after heat curing, the polyimide precursor and The present invention relates to a polyimide resin paste in which fine particles exist as a uniform phase and an IC using this polyimide resin paste.

The polyimide resin paste of the present invention is composed of a solution containing a polyimide precursor and a solvent that mainly functions as a binder, and fine particles of a heat-resistant resin that mainly functions as a thixotropic agent for the paste. . In this paste, the fine particles of heat-resistant resin are dispersed in a solution containing a polyimide precursor and a solvent during blending to develop thixotropic properties, are dissolved in the solvent during heat curing, and are then combined with the polyimide precursor or its reaction product. Forms a uniform film by forming a compatible film. The resulting film is uniform with no pinholes or voids, and has excellent mechanical properties. Furthermore, since a polyimide precursor having a low molecular weight skeleton with excellent heat resistance is used as the binder, it has excellent printability and heat resistance, and a thick film can be formed.

[0008] The polyimide precursor in the present invention is produced by reacting aromatic tetracarboxylic acid dianhydride with excess alcohol in the presence of a solvent to form an aromatic tetracarboxylic acid half ester, if necessary. It is obtained by mixing or reacting the tetracarboxylic acid half ester with preferably about the same molar amount of aromatic diamine.

The solvent may be any solvent as long as it dissolves the aromatic tetracarboxylic dianhydride and the aromatic diamine, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, 1,3-dimethyl- 3, 4, 5, 6
-tetrahydro-2(1H)-pyrimidinone, 1,3-
Nitrogen-containing solvents such as dimethyl-2-imidazolidinone, γ
Lactones such as -butyrolactone and γ-caprolactone, and glymes such as diethylene glycol dimethyl ether and triethylene glycol dimethyl ether are preferably used.

Aromatic tetracarboxylic dianhydride has the general formula

[Chemical formula 1] (where R1 is a tetravalent aromatic hydrocarbon group), for example, pyromellitic dianhydride, 3
, 3',4,4'-benzophenonetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride , 4,4'-sulfonyldiphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, [1,3
-bis(3,4-dicarboxyphenyl)-1,1,3
, 3-tetramethyldisiloxane] dianhydride, 1,1,
1,3,3,3-hexafluoro-2,2-bis(3,
4-dicarboxyphenyl)propane dianhydride, bis(
Examples include 3,4-dicarboxyphenyl) dimethylsilane dianhydride, and one or more of these may be used.

[0011] Alcohols for half-esterifying the aromatic tetracarboxylic dianhydride include monohydric alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, and benzyl alcohol, ethylene glycol, propylene glycol, glycerin, and trihydric alcohol. Examples include polyhydric alcohols such as methylolpropane, cellosolves such as ethylene glycol monomethyl ether, and carbitols such as diethylene glycol monomethyl ether, and one or more of these may be used. In particular, monohydric alcohols such as methanol, ethanol, and butanol are preferably used.

Further, the aromatic diamine used in the present invention has the general formula

embedded image (where R2 is a divalent aromatic hydrocarbon group), such as paraphenylenediamine,
metaphenylenediamine, 4,4'-(or 3,4'
-,3,3'-2,4'-), diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'
-diaminodiphenylsulfone, 4,4'-diaminodiphenyl sulfide, benzidine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4, 4'-di(4-aminophenoxy)phenylsulfone, 1,1,1,3,3,3-hexafluoro2,
2-bis(4-aminophenyl)propane, 3,3'-
Dimethyl-4,4'-diaminodifermethane, 3,3
',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-di(3-aminophenoxy)
There are phenyl sulfones and the like, and one type or two or more types of these can be used.

[0013] If necessary, aliphatic diamines other than the above aromatic diamines, alicyclic diamines, heterocyclic diamines, and the following general formula

[Chemical formula 3] (Here, R3 is a divalent hydrocarbon group having 1 to 10 carbon atoms, R
4, R5, R6, and R7 are monovalent hydrocarbon groups having 1 to 10 carbon atoms, and they may be the same or different. n is an integer from 1 to 10. ) may be used in a proportion of 50 mol% or less of the aromatic diamine. Diaminosiloxane has the effect of increasing the adhesion between the film and the substrate (particularly silicon wafers).

The half-esterification of the aromatic tetracarboxylic dianhydride in the present invention is carried out using an equimolar or excess molar amount of alcohol per mole of the aromatic tetracarboxylic dianhydride. The reaction temperature varies depending on the solvent, alcohol and alcohol derivative used, and is not particularly limited. 80℃ for half esterification using
A reaction temperature of ˜150° C. is preferred. Furthermore, after half-esterification, excess alcohol may be removed to adjust the concentration. The solvent used in the present invention can also be used as the solvent for half-esterification. The reaction temperature for the reaction between the aromatic tetracarboxylic acid ester and the aromatic diamine is arbitrary as long as it can provide the necessary low molecular weight polyimide precursor, specifically a polyamic acid ester oligomer or a polyimide oligomer. Usually 40-25
A temperature of 0°C, preferably 60 to 200°C is preferably used. When simply mixing an aromatic tetracarboxylic acid half ester and an aromatic diamine, it is preferable to mix them at around room temperature.

[0015] A polyimide precursor consisting of a mixture of aromatic tetracarboxylic acid half ester and aromatic diamine, which are essentially monomers, is preferably used because it has excellent storage stability as a paste. A low molecular weight polyimide precursor is used. Preferably, those having a number average molecular weight of 5,000 or less are used. By using a low molecular weight polyimide precursor, the paste can have a high solids concentration and thick films can be formed. Furthermore, the dynamic elastic modulus of the paste can be reduced, and it is possible to suppress the paste from turning behind the plate during printing.

[0016] In this specification, the number average molecular weight is a polystyrene equivalent value determined by gel permeation chromatography using polystyrene of known molecular weight as a calibration curve. Specifically, the measurement was performed under the following conditions. Equipment: Hitachi 655A column: Gelpak GL- manufactured by Hitachi Chemical Co., Ltd.
S300 MDT-S (300 mm x 8 mmφ) 2 bottles Eluent: Tetrahydrofuran/dimethylformamide = 1/1 (volume), H3PO4 (0.06 mol/l)/LiBr・H2O (0.03 mol/l) Flow rate: 1 ml /min Detector: UV (270nm)

The polyimide precursor obtained as described above has a temperature of 100 to 400°C, preferably 250°C.
By heating and curing at ~350°C, a high molecular weight polyimide resin with excellent heat resistance and mechanical properties is obtained.

The heat-resistant resin fine particles used in the present invention are essentially solvent-soluble thermoplastic or thermosetting heat-resistant resin fine particles. From the viewpoint of heat resistance and mechanical properties, the above-mentioned polyamide resins, polyamideimide resins, polyimide resins (polyamic acid resins that are precursors of polyimide resins, and tetracarboxylic dianhydrides form a complex with this dianhydride. A composition obtained by mixing or reacting a diamine with a complex obtained by reacting a complex with a suitable solvent or a polyamic acid oligomer (the solvent is preferably N-methyl-2-pyrrolidone, pyridine,
Fine particles of ε-caprolactam (including ε-caprolactam, etc.) are used.

The fine particles of heat-resistant resin are used for the purpose of imparting thixotropy to the paste and increasing the solid content of the paste to form a thick film. As the heat-resistant resin fine particles, polyamide resins, polyamideimide resins, and polyimide resins having an average particle diameter of 40 μm or less are preferably used. When the paste of the present invention is used for screen printing, the thixotropic property of the paste,
Considering the uniformity of the film and the harmony with the film thickness, the heat-resistant resin fine particles preferably have an average particle diameter of 0.1 to 10 μm.
It is said that

Fine particles of heat-resistant resin can be obtained by a non-aqueous dispersion polymerization method or a precipitation polymerization method, but other methods are also available, for example, by mechanically pulverizing powder recovered from a resin solution, or by adding a poor solvent to a resin solution. Any method can be used, including a method of forming fine particles under high shear, and a method of drying sprayed oil droplets of a resin solution to obtain fine particles.

The thermal decomposition initiation temperature of the fine particles of thermosetting and thermoplastic heat-resistant resins is preferably 250°C or higher, particularly preferably 350°C or higher, and the glass transition temperature is preferably 200°C or higher, particularly preferably The temperature is 260°C or higher, and these are used alone or in combination.

The solvent used in the present invention can be used, for example, in ``Solvent Handbook'' (Kodansha, published in 1976), 143-85.
The solvents listed on page 2 are used. For example, N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, 1,3-dimethyl-3,4,5,6-
Nitrogen-containing compounds such as tetrahydro-2(1H)-pyrimidinone and 1,3-dimethyl-2-imidazolidinone, sulfur compounds such as sulfolane and dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ- Lactones such as heptalactone, α-acetyl-γ-butyrolactone, and ε-caprolactone, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl (or diethyl, dipropyl, dibutyl) ether, triethylene glycol dimethyl (or diethyl, dipropyl, ethers such as dibutyl) ether, tetraethylene glycol dimethyl (or diethyl, dipropyl, dibutyl) ether, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetophenone, butanol, octyl alcohol,
Ethylene glycol, glycerin, diethylene glycol monomethyl (or monoethyl) ether, triethylene glycol monomethyl (or monoethyl) ether,
Alcohols such as tetraethylene glycol monomethyl (or monoethyl) ether, phenols such as phenol, cresol, xylenol, esters such as ethyl acetate, butyl acetate, ethyl cellosolve acetate, butyl cellosolve acetate, toluene, xylene, diethylbenzene, cyclohexane, etc. Hydrocarbons, halogenated hydrocarbons such as trichloroethane, tetrachloroethane, and monochlorobenzene are used.

The boiling point of the solvent is preferably 100° C. or higher, particularly 150° C. or higher, considering the pot life of the paste during screen printing.

In the polyimide resin paste of the present invention, before heat curing, the fine particles exist as a heterogeneous phase in contrast to the homogeneous phase consisting of the polyimide precursor and solvent, and after heat curing, the polyimide precursor, fine particles, and solvent It can be obtained by adjusting the composition of the polyimide precursor, heat-resistant resin fine particles, and solvent so that it exists as a homogeneous phase.

That is, it is preferable to use polyimide precursors and heat-resistant resin particles that have the property of being compatible with each other during heat curing. Preferably, the polyimide precursor is one that dissolves well in the solvent at room temperature and during heat curing. Preferably, the fine particles of the heat-resistant resin are those that do not dissolve in the solvent at room temperature, but dissolve during heat curing. As such a solvent, a single solvent or a mixed solvent consisting of two or more types of solvents may be used. As the sole solvent, it is preferable to use a solvent whose solubility in the fine particles of the heat-resistant resin is strongly dependent on temperature, that is, one which exhibits almost no solubility at room temperature and exhibits good solubility during heat curing. In addition, as a mixed solvent, two types of solvents with different solubility and drying properties are used: a good solvent that shows good solubility for heat-resistant resin fine particles, and a poor solvent that does not show solubility. A mixed solvent consisting of two types of solvents, one with a boiling point and one with a low boiling point, is preferably used. The boiling point of the good solvent is higher than the boiling point of the poor solvent, preferably 5°C, more preferably 20°C higher. In this case, the ratio of the good solvent to the poor solvent is adjusted so that the fine particles of the heat-resistant resin are insoluble in the mixed solvent at room temperature but dissolve when heated. By doing so, the fine particles are stably dispersed in the paste during storage and printing, and when heated after printing, the low boiling point poor solvent is first volatilized and removed from the paste, and the fine particles are dissolved in the remaining high boiling point good solvent. Then, it is uniformly dissolved and formed into a film with the polyimide precursor or its reaction product, resulting in a uniform film with no pinholes or voids and excellent mechanical properties.

In the present invention, a polyimide resin paste is obtained by dispersing fine particles of a heat-resistant resin in a solution of a polyimide precursor and a solvent.

The ratio of the polyimide precursor to the heat-resistant resin fine particles is preferably such that the total amount is 100 parts by weight, and 95 to 30 parts by weight of the heat-resistant resin fine particles are used for 5 to 70 parts by weight of the polyimide precursor. Increasing the proportion of fine particles of heat-resistant resin can increase thixotropy and dry film thickness.

The thixotropic coefficient of the paste was determined using an E-type viscometer (Model EHD-U, manufactured by Tokyo Keiki Co., Ltd.) using a sample amount of 0.
4g, measured at a measurement temperature of 25°C. Rotation speed 1 rpm and 1
Apparent viscosity of paste at 0 rpm, ratio of η1 and η10,
It is expressed as η1/η10.

The concentration of the polyimide precursor and heat-resistant resin fine particles in the paste is preferably such that the viscosity of the paste is 30.
~10,000 poise and a thixotropy coefficient of 1.5 or more. If the viscosity of the paste is less than 30 poise, the paste tends to sag after printing;
If it exceeds 0,000 poise, printing workability will decrease. Particularly preferably, it is 300 to 5,000 poise. Specifically, the total concentration of the polyimide precursor and heat-resistant resin fine particles in the paste is preferably 10 to 90% by weight.
It is said that If it is less than 10% by weight, it will be difficult to increase the dry film thickness, and if it exceeds 90% by weight, the fluidity of the paste will be impaired.

[0030] As a method for dispersing heat-resistant resin fine particles in a solution containing a polyimide precursor and a solvent, roll kneading, mixer mixing, etc., which are usually used in the paint field, are applied, and methods that ensure sufficient dispersion are used. If so, there are no particular restrictions. Most preferred is multiple kneading using three rolls.

[0031] The thixotropy coefficient of the paste in the present invention is preferably 1.5 or more. If it is less than 1.5, sagging is likely to occur in the paste transferred to the substrate,
It is difficult to obtain sufficient pattern accuracy. After the paste of the present invention is applied to the substrate, it preferably has a final
A tough film can be formed by heating and curing at 00°C for 1 to 120 minutes.

[0032] The paste of the present invention may contain antifoaming agents, pigments, paints, plasticizers, antioxidants, and the like, if necessary.

The polyimide resin paste of the present invention can be used for devices such as monolithic ICs using silicon wafers as substrates, hybrid ICs using ceramic or glass substrates, thermal heads, image sensors, multi-chip high-density mounting boards, flexible wiring boards, It can be widely used in interlayer insulating films and/or surface protective films of various wiring boards such as rigid wiring boards, various heat-resistant printing inks, heat-resistant adhesives, etc., and is extremely useful industrially.

When the polyimide resin paste of the present invention is used as a protective film for a semiconductor device such as a monolithic IC, α-ray source substances such as uranium and thorium, and ionic impurities such as sodium, potassium, copper, and iron can be used. It is preferable to reduce the content of . The total content of α-ray source substances such as uranium and thorium in the protective film is preferably 1 ppb or less, more preferably 0.2 ppb or less. This is because the influence of the alpha rays emitted from the protective film on malfunction of the device decreases rapidly at 0.2 to 1 ppb. If the total content of α-ray source substances such as uranium and thorium in the obtained protective film exceeds 0.2 to 1 ppb, the monomers used in the production of the resin, the solvent, the precipitant used in the purification of the resin, etc. By purifying organic liquids, etc., the total content of α-ray source substances such as uranium and thorium can be reduced. Purification is carried out by distilling, sublimating, recrystallizing, extracting, etc. the monomers, solvents, precipitants used for resin purification, organic liquids, etc. used in the production of resin, or by purifying the synthesized resin solution in a purified poor solvent. It is convenient to perform the precipitation step multiple times.

Furthermore, in order to reduce corrosion and leakage during use, the content of ionic impurities such as sodium, potassium, copper, iron, etc. is preferably 2 ppm or less, more preferably 1 ppm or less. If the total content of ionic impurities in the obtained film exceeds 1 to 2 ppm, the total content of ionic impurities can be reduced by refining the monomers used in the production of the above resin in the same process as the above purification. can be reduced. It is not necessary to purify all of the monomers used. For example, purification may be performed only on the monomer or only on the monomer and the solvent.

The IC used in the present invention includes a monolithic IC, a hybrid IC, a multi-chip high-density mounting board, and the like.

The monolithic IC has the structure shown in FIG. 1, for example, and the polyimide resin paste of the present invention is applied onto the LSI chip 2 and heated to form the polyimide resin film 1 (surface protection film). It is said that

In FIG. 1, 1 is a polyimide resin film, 2 is an LSI chip, 3 is a bonding wire, 4 is a resin package, 5 is a lead, and 6 is a support. The hybrid IC has the structure shown in FIG. 2, for example,
A polyimide resin paste according to the present invention is applied onto the first layer wiring 11 and the resistance layer 12 and heated to form a polyimide resin film 10 (interlayer insulation film). A second layer wiring 9 is formed on this. In FIG. 2, 7 is a diode chip, 8 is solder, 9 is a second layer wiring, 10 is a polyimide resin film, 11 is a first layer wiring, 12 is a resistance layer, 1
3 is an alumina substrate.

The multi-chip high-density mounting board has, for example, the structure shown in FIG.
0 by a known method, coating the polyimide resin paste of the present invention, and forming a polyimide resin film 14 (interlayer insulation film) by heating, etc., the copper/polyimide A resin multilayer wiring layer 19 is formed. In FIG. 3, 17 is an LSI chip and 18 is a solder.

[0040]

[Examples] Next, the present invention will be explained with reference to comparative examples and examples.

Comparative Example 1 (1) Preparation of polyimide resin 3,3',4,4'-benzophenonetetracarboxylic acid was added while passing nitrogen gas through a four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube. Dianhydride 11.729g (
0.0364 mol), 7.289 g (0.0364 mol) of 2,4'-diaminodiphenyl ether, and 72 g of N-methyl-2-pyrrolidone were charged. 2 at room temperature under stirring
The reaction proceeded for 0 hours. Next, 52 g of acetic anhydride and 26 g of pyridine were added, and the mixture was left at room temperature for 12 hours. The obtained solution was poured into methanol, and the precipitated solid resin in the form of fine particles was recovered. After thoroughly boiling and washing this solid resin with methanol, it was dried under reduced pressure at 80°C for 10 hours to obtain a powder of a polyimide resin soluble in N-methyl-2-pyrrolidone (number average molecular weight: 35 ,000)
I got it.

[C4]

(2) Preparation of polyimide resin fine particles 218 g (1 mol) of pyromellitic dianhydride and 218 g (1 mol) of pyromellitic dianhydride were passed through a four-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, and moisture meter. 1672 g of N-methyl-2-pyrrolidone (water content 0.03%) was added, and the temperature was raised to 50° C. while stirring, and the temperature was maintained at the same temperature for 0.5 hours to completely dissolve and form a homogeneous solution. To this, 100 g (0.5 mol) of 4,4'-diaminodiphenyl ether and 99 g (0.5 mol) of 4,4'-diaminodiphenylmethane were added,
The temperature was immediately raised to 110° C. and kept at the same temperature for 20 minutes to completely dissolve and form a uniform solution. Then, in about 2 hours, 20
The temperature was raised to 0°C, and the reaction was continued at the same temperature for 3 hours. On the way, about 1
Precipitation of fine particles of polyimide resin was observed at 40°C. Additionally, water distilled out during the reaction was promptly removed from the system. Fine particles of yellow-brown polyimide resin dispersed in N-methyl-2-pyrrolidone were obtained, which were collected by filtration, further boiled in acetone twice, and then dried at 200°C under reduced pressure for 5 hours. Ta. The shape of the polyimide resin fine particles is approximately spherical, porous, and has an average particle diameter (
Based on TA-II model manufactured by Coulter Electronics. (same below) was 8 μm, and the maximum particle size was 40 μm or less. This polyimide resin fine particle is insoluble in N-methyl-2-pyrrolidone and has a repeating unit of the following formula.

[C5]

(3) Preparation of polyimide resin paste 15 g of the soluble polyimide resin from (1) above was mixed with N-methyl-
25 g of the polyimide resin fine particles prepared in (2) above were added to a solution dissolved in 60 g of 2-pyrrolidone, and first roughly kneaded in a mortar and then kneaded by passing it through six times using a high-speed triple roll to form the polyimide resin fine particles. A polyimide resin paste containing dispersed polyimide resin was obtained.

Comparative Example 2 (1) Preparation of polyimide resin fine particles 3,3',4,4'-biphenyltetracarboxylic acid was added while passing nitrogen gas through a four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube. Acid dianhydride 10.711g (0.
0364 mol), 7.289 g (0.0364 mol) of 2,4'-diaminodiphenyl ether and N-methyl-2
- 72g of pyrrolidone was charged. The reaction was allowed to proceed for 10 hours at room temperature under stirring. Next, 52 g of acetic anhydride and 26 g of pyridine
g was added and left at room temperature for 12 hours. The resulting paste was poured into methanol, and the precipitated solid resin in the form of fine particles was recovered. This solid resin was sufficiently boiled and washed with methanol, and then dried under reduced pressure at 80° C. for 10 hours to obtain a powdered polyimide resin (number average molecular weight: 31,000) having repeating units of the following formula. This polyimide resin is pulverized using a pulverizer, with an average particle size of 4.5 μm and a maximum particle size of 40 μm.
Polyimide resin microparticles having repeating units of the following formula, which are soluble in nitrogen-containing solvents such as N-methyl-2-pyrrolidone and insoluble in cellosolves such as butyl cellosolve acetate, were obtained.

[C6]

(2) Preparation of polyimide resin paste Comparative Example 1, 12 g of the soluble polyimide resin prepared in (1)
1,3-dimethyl-3,4,5,6-tetrahydro-
The above (
18 g of the polyimide resin fine particles prepared in 1) were added and first roughly kneaded in a mortar and then kneaded six times using a high-speed triple roll to obtain a polyimide resin paste in which the polyimide resin fine particles were dispersed.

Example 1 (1) Preparation of polyimide precursor 3,3',4,4'-benzophenonetetracarboxylic acid dihydrate was placed in a four-necked flask equipped with a thermometer, a stirrer, a nitrogen introduction tube, and a cooling tube. Anhydride 32.223g (0.1
000 mol), 264.801 g (0.9000 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 92.601 g (2.01 mol) of ethanol and N
-Methyl-2-pyrrolidone (589 g) was charged and heated while stirring to raise the temperature to 100°C. The mixture was reacted at the same temperature for 3 hours to obtain an aromatic tetracarboxylic acid half ester. After cooling to room temperature, 200.240 g (1.000 mol) of 4,4'-diaminodiphenyl ether was charged and dissolved to form a solution (solid content concentration: 50% by weight) of polyimide precursor (number average molecular weight: 1,000). Obtained.

(2) Preparation of fine particles of heat-resistant resin (1)
), 44 g of the N-methyl-2-pyrrolidone solution (solid content concentration: 50% by weight) of the polyimide precursor prepared in Comparative Example 2, 23 g of the polyimide resin fine particles prepared in (1), and 33 g of butyl cellosolve were first coarsely ground in a mortar. The mixture was kneaded and then kneaded six times using a high-speed triple roll to obtain a polyimide resin paste in which polyimide resin fine particles were dispersed. Here, the boiling point of N-methyl-2-pyrrolidone is 20
At 2°C, the boiling point of butyl cellosolve is 171°C.

Example 2 (1) Preparation of polyimide precursor 1,1,1,3,3,3-
Hexafluoro-2,2-bis(3,4-dicarboxyphenyl)propane dianhydride 444.24g (1 mol)
, 92.601 g (2.01 mol) of ethanol and 1,3
-dimethyl-3,4,5,6-tetrahydro-2(1H
)-pyrimidinone (737 g) was charged and heated while stirring to raise the temperature to 100°C. The mixture was reacted at the same temperature for 3 hours to obtain an aromatic tetracarboxylic acid half ester. After cooling to room temperature, 200.240 g (1.000 mol) of 2,4'-diaminodiphenyl ether was charged and dissolved to obtain a solution (solid content concentration: 50% by weight) of a polyimide precursor (number average molecular weight: 900). .

(2) Preparation of fine particles of heat-resistant resin As the aromatic tetracarboxylic dianhydride, 3,3',4,4'-
Bis(3) was used instead of biphenyltetracarboxylic dianhydride.
,4-dicarboxyphenyl)dimethylsilane dianhydride 12.826 g (0.0364 mol), as aromatic diamine, 7.289 g of 4,4'-diaminodiphenyl ether instead of 2,4'-diaminodiphenyl ether
Comparative Example 2, except using (0.0364 mol), (1)
A powdered polyimide resin was obtained in exactly the same manner as above. This polyimide resin is pulverized using a pulverizer, and the average particle size is 4.
μm, 1,3-dimethyl-3 with a maximum particle size of 40 μm or less
, 4,5,6-tetrahydro-2(1H)-pyrimidinone and other nitrogen-containing solvents, and is insoluble in cellosolves such as butyl cellosolve acetate. Polyimide resin having repeating units of the following formula (number average molecular weight: 40 ,000) was obtained.

[C7]

(3) Preparation of polyimide resin paste A 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone solution of the polyimide precursor prepared in (1) above (solid content concentration: 50% by weight) 44g, above (
23 g of the polyimide resin fine particles prepared in 2) and 33 g of butyl cellosolve acetate were first roughly kneaded in a mortar, and then kneaded by passing them through six times using a high-speed triple roll to obtain a polyimide resin paste in which the polyimide resin fine particles were dispersed. . Here, the boiling point of 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone is 246
°C, the boiling point of butyl cellosolve acetate is 192 °C.

Example 3 (1) Preparation of polyimide precursor Example 1 and (1) except that N-methyl-2-pyrrolidone in the solvent was changed to 1,3-dimethyl-2-imidazolidinone.
), and a solution of polyimide precursor (number average molecular weight: 1,000) (solid content concentration: 50% by weight) was prepared.
I got it.

(2) Preparation of polyimide resin paste 44 g of 1,3-dimethyl-2-imidazolidinone solution (solid content concentration: 50% by weight) of the polyimide precursor prepared in (1) above, Comparative Example 2, 23 g of the polyimide resin fine particles prepared in (1) and 33 g of diethylene glycol monoethyl ether acetate were first roughly kneaded in a mortar, and then kneaded by passing them through six times using a high-speed triple roll to form a polyimide system in which the polyimide resin fine particles were dispersed. A resin paste was obtained. Here, the boiling point of 1,3-dimethyl-2-imidazolidinone is 226°C, and the boiling point of diethylene glycol monoethyl ether acetate is 217°C.

Example 4 (1) Preparation of polyimide precursor Example 1, N-methyl-2-pyrrolidone solution of the polyimide precursor prepared in (1) (solid content concentration: 50% by weight)
were reacted at 80° C. for 4 hours to obtain an N-methyl-2-pyrrolidone solution (solid content concentration: 50% by weight) of a polyimide precursor (polyamic acid ester oligomer) having a number average molecular weight of 3,100.

(2) Preparation of polyimide resin paste N-methyl-2 of the polyimide precursor prepared in (1) above
- 44 g of pyrrolidone solution (solid concentration: 50% by weight),
Comparative Example 2, polyimide resin fine particles 23 prepared in (1)
g and 33 g of butyl cellosolve were first coarsely kneaded in a mortar, and then kneaded by passing through a high-speed triple roll six times to obtain a polyimide resin paste in which polyimide resin fine particles were dispersed.

Example 5 (1) Preparation of polyimide precursor 3,3',4, purified by recrystallization from acetic anhydride was placed in a four-necked flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube.
4'-benzophenone tetracarboxylic dianhydride 11.
602g (0.0360 mol), recrystallized from a mixture of toluene and diethyl ether in a weight ratio of 1:1 [1,
3-bis(3,4-dicarboxyphenyl)-1,1,
3,3-tetramethyldisiloxane dianhydride 0.80
8g (0.0019 mol), 23g of N-methyl-2-pyrrolidone purified by vacuum distillation, and 3.5g of ethanol.
g was charged while passing nitrogen gas. 10 while stirring
The mixture was reacted at 0° C. for 3 hours to obtain an aromatic tetracarboxylic dianhydride half ester. After cooling to room temperature, 7.589 g (0.0379 mol) of 2,4'-diaminodiphenyl ether recrystallized from a mixture of methanol and water at a weight ratio of 8:2 (methanol:water) was charged, and the mixture was heated to room temperature. Dissolve polyimide precursor (number average molecular weight: 1,000)
A solution (solid content concentration: 50% by weight) was obtained.

(2) Thermometer for preparing fine particles of heat-resistant resin;
3,3′, purified by recrystallization from acetic anhydride, was placed in a four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a moisture meter.
4,4'-benzophenonetetracarboxylic dianhydride 6
．． 106g (0.0190mol) and 3,3',4,4
'-Biphenyltetracarboxylic dianhydride 5.578g
(0.0190 mol) was recrystallized using a mixture of toluene and diethyl ether in a weight ratio of 1:1 [1,3
-bis(3,4-dicarboxyphenyl)-1,1,3
,3-tetramethyldisiloxane] dianhydride 0.851
g (0.0020 mol), 7.993 g of 2,4'-diaminodiphenyl ether recrystallized using a mixture of methanol and water at a weight ratio of 8:2 (methanol:water)
0.0400 mol) and 84 g of N-methyl-2-pyrrolidone purified by vacuum distillation were charged while passing nitrogen gas. After proceeding with the reaction for 10 hours at room temperature under stirring, 18
The temperature was raised to 5°C, and the reaction was continued at the same temperature for 10 hours. in the middle,
The distilled water was promptly removed from the reaction system. The resulting solution was diluted with 735 g of N-methyl-2-pyrrolidone purified by vacuum distillation to obtain a solution with a solid content concentration of 2.5% by weight. This was spray-dried using a Mobil Minor type spray dryer manufactured by Ashizawa Waniro Atomizer Co., Ltd. to form fine particles, and then classified to have an average particle size of 4.5 μm and a maximum particle size of 40 μm or less, soluble in N-methyl-2-pyrrolidone.
Fine particles of polyimide resin having repeating units of the following formula which are insoluble in butyl cellosolve were obtained. The number average molecular weight of this polyimide resin was 33,000.

[Chemical formula 8]

(3) Preparation of polyimide resin paste Add the above (2) to 44 g of the N-methyl-2-pyrrolidone solution (solid content concentration: 50% by weight) of the polyimide precursor in (1) above.
) 23 g of polyimide resin fine particles and 33 g of butyl cellosolve were first roughly kneaded in a mortar, and then kneaded by passing them through six times using a high-speed triple roll to obtain a polyimide resin paste in which polyimide resin fine particles were dispersed. The solvent was removed from this paste, and the content of uranium and thorium was examined by activation analysis, and the detection limit of each was 0.
0.02 ppb or less, and 0.05 ppb or less. Moreover, the content of ionic impurities of sodium, potassium, copper, and iron was each 2 ppm or less. Next, this paste was applied to the surface of a MOS type RAM with a density of 16K bits by screen printing, and
The polyimide protective film having a thickness of about 20 μm was formed by heating and curing at 00° C., 250° C., and 350° C. for 0.5 hours, respectively. Then, the obtained semiconductor element is packaged in a ceramic package using low melting point glass as a sealing adhesive for about 4 hours.
It was sealed at 50°C. The soft error rate of this semiconductor device was 30 fit.

The pastes obtained in Comparative Examples 1 and 2 and Examples 1 to 4 were screen printed on a silicon wafer substrate.
1 hour at 00℃, 0.5 hour at 200℃, 0 at 250℃
．． The following characteristics of the film obtained by heating and curing at 350° C. for 5 hours and 0.5 hour were evaluated, and the results are shown in Table 1. Screen printing has a porosity of 71% and a stencil thickness of 1
The test was carried out using a 30 μm, solvent-resistant emulsion plate at a squeegee speed of 30 mm/s. The plate turning property of the paste was determined by visually observing whether the paste adhered to the back surface of the plate after 20 shots of printing. The film thickness was measured using an electromagnetic film thickness meter.

[0059] To determine the pinhole density, an aluminum plate was used as the base material, a 0.2% saline solution containing an appropriate amount of phenolphthalein was applied to the surface of the film, this solution was used as the positive electrode, the aluminum plate was used as the negative electrode, and a 20V DC current was applied. A voltage was applied for 1 minute, and the number of pinholes generated was measured. The tensile strength was measured using a glass plate as a base material and a film peeled from the glass plate using a tensile tester (Tensilon Universal Tester Model UCT-5T manufactured by Orientech Co., Ltd.). The glass transition temperature was measured for the film peeled off from the glass plate using a differential scanning calorimeter (Model 910 manufactured by DuPont) at a heating rate of 5° C./min.

[0060]

[Table 1]

[0061]

Effects of the Invention From Table 1, it can be seen that in the polyimide resin pastes of Examples 1 to 4 in which a specific polyimide precursor, fine particles of soluble heat-resistant resin, and a solvent were combined, the blended filler remained intact in the film. Compared to the paste of Comparative Example 1, which forms a non-uniform film, a uniform film without pinholes can be formed, and it is shown that the tensile strength is significantly superior. Furthermore, by using a low molecular weight polyimide precursor as a binder, the pastes of Examples 1 to 4 have better printability because the paste does not run behind the plate, compared to the paste of Comparative Example 2 which uses a high molecular weight polyimide resin. Are better. It is also shown that the solid content concentration is high and a thick film can be formed.

[0062]

[Brief Description of the Drawings] Figure 1 is a cross-sectional view of a monolithic IC using the polyimide resin paste of the present invention, Figure 2 is a cross-sectional view of a hybrid IC using the polyimide resin paste of the present invention, and Figure 3 is a cross-sectional view of a monolithic IC using the polyimide resin paste of the present invention. FIG. 2 is a cross-sectional view of a multi-chip high-density mounting board using the polyimide resin paste of the invention.

[Explanation of symbols]

1 Polyimide resin film
2 LIS chip 3 Bonding wire
4 Resin package 5 Lead
6 Support 7 Diode chip
8 Solder 9 Second layer wiring
10 Polyimide resin film 11 First layer wiring
12 Resistance layer 13 Alumina substrate
14 Polyimide resin film 15 Wiring layer
16 Wiring layer 17 LSI chip
18 Solder 19 Copper/polyimide resin multilayer wiring layer
20 Ceramic multilayer wiring board

Claims (4)

[Claims] [Claim 1] A low molecular weight polyimide precursor obtained by mixing or reacting an aromatic diamine with an aromatic tetracarboxylic acid half ester obtained by reacting an aromatic tetracarboxylic dianhydride and an alcohol, heat resistant. Contains fine resin particles and a solvent. Before heat curing, the fine particles exist as a heterogeneous phase in contrast to a homogeneous phase consisting of a polyimide precursor and solvent, and after heat curing, the polyimide precursor and fine particles exist as a homogeneous phase. polyimide resin paste. 2. The polyimide resin paste according to claim 1, wherein the fine particles are polyimide resin, polyamideimide resin, or polyamide resin having an average particle diameter of 40 μm or less. Claim 3: The paste has a thixotropy coefficient of 1.
The polyimide resin paste according to claim 1 or 2, which has a polyimide resin paste of 5 or more. 4. An IC having an interlayer insulating film and/or a surface protection film obtained from the polyimide resin paste according to claim 1, 2, or 3.