JP2000063543A - Polyimide film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polyimide film having a high elasticity, coefficient of linear expansion near to copper, sufficient tenacity, low water absorption coefficient, hygroscopic swelling coefficient, or the like by forming the film of a specific polyamic acid. SOLUTION: This polyimide film (pref. having an average coefficient of linear expansion of 15-30 ppm in the range of 100-200 deg.C, a tensile elasticity of 4.5-8.5 G.Pa, an elongation of >=20% at break, a coefficient of linear expansion of <=10 ppm and a glass transition temperature of >=200 deg.C) is produced by forming the film with a polyamic acid obtained by reacting (A) p- phenylenebis(trimellitic acid monoester anhydride), (B) oxydiphthalic acid dianydride, (C) p-phenylenediamine and (D) 4,4'-diaminodiphenyl ether in (E) an organic solvent. The film is pref. used for products laminated with metal (esp. copper) and is useful, e.g. in flexible printed board having thin wiring lines or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film having excellent physical property balance, which can provide low warpage and high dimensional stability in a product laminated with metal, especially copper.

[0002]

2. Description of the Related Art Polyimide films have heat resistance, insulation properties, solvent resistance, low temperature resistance, etc., and are widely used as materials for computer and IC controlled electric / electronic equipment parts.

In recent years, with the miniaturization and thinning of electric devices and electronic devices for controlling computers and ICs, wiring boards and ICs have been developed.
The packaging materials are also required to be smaller and thinner. For this reason, the wiring pattern applied to them becomes fine, and it is necessary that the polyimide film used for the flexible wiring board, the carrier tape for TAB and the like also has a small dimensional change due to heating and tension and further moisture absorption. Further, as the material is made thinner, it is necessary to maintain the "stiffness" of the entire laminate and stabilize the processing process.

In order to meet such needs, it is desired that the polyimide film has a small linear expansion coefficient, a high elastic modulus and a low hygroscopic expansion coefficient. However, when manufacturing a flexible wiring board or an IC package, a polyimide film and a copper foil are laminated and processed. Therefore, it is not preferable that the coefficient of linear expansion of the film is significantly different from that of copper. That is, if the coefficient of linear expansion of the polyimide film and that of the copper foil are significantly different, the laminated product will be warped, making it difficult to process, and as a result, the overall dimensional accuracy and yield will be reduced.

First, in order to increase the elastic modulus of a polyimide film, it is widely known that a monomer having a rigid structure, that is, a monomer having high linearity may be used. However, if a large amount of a monomer having high linearity is used, the linear expansion coefficient of the film becomes too low, which makes it unsuitable for use in bonding with a copper foil.

[0006] In order to achieve a relatively high elastic modulus while not lowering the linear expansion coefficient too much, a monomer having a relatively rigid structure is used, and it is produced by a thermal curing method without using a chemical imidizing agent, Although there is an example in which the method of softening the orientation in the plane direction is adopted, the thermal curing method has a disadvantage that the heating time required is longer than that of the chemical curing method and the productivity is poor. Furthermore, when a rigid and highly linear monomer is used, the flexibility of the film is generally impaired, and there is a possibility that it may be difficult to fold, which is one of the advantages as a flexible wiring board. .

In semiconductor package applications and the like, it is required that the water absorption rate be as low as possible from the viewpoint of semiconductor reliability, and that the hygroscopic expansion coefficient be low from the viewpoint of dimensional stability. In order to reduce the water absorption rate and the coefficient of hygroscopic expansion, it is effective to reduce the amount of imide groups in the molecular structure. Therefore, a long-chain monomer containing a plurality of bending groups in the main chain is often used. However, as a result, the elastic modulus is lowered and the linear expansion coefficient is excessively increased, and the dimensional stability is sacrificed.
In an extreme case, the thermoplastic resin has Tg at a low temperature of, for example, 200 ° C. or lower, and is not suitable for use as a base film. When a linear and long monomer is used, packing of molecular chains becomes difficult, sufficient toughness cannot be expressed, and in some cases, it becomes difficult to form a film.

As described above, as the characteristics of the polyimide film, there are many points to be considered in addition to the reduction of the high elastic modulus, the low linear expansion coefficient and the water absorption. However, it is a particularly difficult situation to obtain a polyimide film having a plurality of good properties, because if one of the properties is to be satisfied, the other properties are sacrificed.

[0009]

Therefore, the inventors of the present invention have solved the above-mentioned problems, and have the characteristics such as high elastic modulus, linear expansion coefficient close to that of copper, sufficient toughness, low water absorption coefficient and hygroscopic expansion coefficient. The present invention has been achieved as a result of earnestly studying the production of a polyimide film suitable for a flexible printed circuit board having a fine wiring and a TAB film which are also held.

[0010]

In view of the above requirements, the present inventors have found a unique case in which a polyimide film having a specific composition can achieve a highly balanced property.

The main points of the polyimide film of the present invention are p-phenylene bis (trimellitic acid monoester anhydride), oxydiphthalic acid dianhydride, p-phenylenediamine, and 4,4'-diaminodiphenyl ether. It is to be produced from a polyamic acid obtained by reacting in an organic solvent.

In such a polyimide film, the p
-Phenylene bis (trimellitic acid monoester anhydride) is in the range of more than 0 and 90 mol% or less, preferably 1 to 90 mol%, based on the total acid anhydride, and oxydiphthalic acid dianhydride is the total acid. 10 to 100 for anhydrous
Less than mol%, preferably from 10 mol% to 99 mol%, wherein p-phenylenediamine is 2 relative to all diamines.
5 to 90 mol%, and 4,4′-diaminodiphenyl ether is 10 to 75 mol% based on all diamines.

In such a polyimide film, 100
The average coefficient of linear expansion between 15 ° C and 200 ° C is 15 to 30 pp
m, the tensile elastic modulus is 4.5 to 8.5 GPa, the elongation at break is 20% or more, the hygroscopic expansion coefficient is 10 ppm or less, and the Tg is 200 ° C. or more.

The gist of the method for producing a polyimide film of the present invention is that 4,4'-diaminodiphenyl ether and paraphenylenediamine are dissolved in an organic solvent, and p-phenylene bis (trimellitic acid monoester anhydride is added thereto. Of the polyamic acid polymer obtained by adding oxydiphthalic acid dianhydride, and dehydrating and ring-closing the polyamic acid polymer.

Preferably, in the method for producing a polyimide film of the present invention, the dehydration ring closure can be carried out in the presence of an imidizing agent of an acid anhydride and a tertiary amine.

The p-phenylene bis (trimellitic acid monoester anhydride) monomer (hereinafter referred to as TMHQ) is
When combined with para-phenylenediamine (PDA), it has a rod-like structure and exhibits high elasticity of the film.
Since there is an ester bond on the main chain structure and it is slightly flexible in terms of heat, the linear expansion coefficient does not drop extremely compared with the case where, for example, pyromellitic acid is used.
Further, the ester bond also has the effect of relaxing the polarization of the imide ring, lowering the water absorption rate and lowering the water absorption expansion rate. However, T
When combined with PDA, MHQ is structurally too hard, its linear expansion coefficient is still low, and its toughness is insufficient.
Even if the diaminodiphenyl ether is copolymerized, the coefficient of linear expansion becomes too low and the toughness is insufficient when an elastic modulus above a certain level is to be obtained.

Oxydiphthalic acid dianhydride (hereinafter referred to as ODP
A) can be used to polymerize PDA and diaminodiphenyl ether to achieve an appropriately high elastic modulus and an appropriate linear expansion coefficient that is not inconvenient in combination with copper, and sufficient toughness. However, ODPA alone does not significantly lower the water absorption rate, and TMHQ is further copolymerized in order to reduce the moisture absorption characteristics and keep various characteristics favorable.
The configuration of the present invention is very effective. That is, according to the present invention, while having a certain heat resistance, adhesiveness, etc., a well-balanced polyimide film having high elastic modulus, high elongation at break, low linear expansion coefficient, and low hygroscopic expansion coefficient. can get.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The term "monomer" of the present invention means
Refers to either monomeric diamine or tetracarboxylic dianhydride.

As the characteristics of the polyimide film, the tensile modulus and the elongation at break are AS and AS, respectively.
The value measured according to TM-D882. The average coefficient of linear expansion is determined by using TMA8140 manufactured by Rigaku Denki Co., Ltd., increasing the temperature at a rate of 10 ° C. for 1 minute in the presence of nitrogen, and measuring the value at 100 ° C. to 200 ° C. . The coefficient of hygroscopic expansion is such that the polyimide film is subjected to the minimum weight (about 3 g for a sample of 5 mm x 20 mm) so that it does not sag, and the humidity is adjusted to 30 RH% and absorbed until completely saturated. The size is measured, the humidity is adjusted to 90 RH% and saturated moisture is similarly absorbed, and then the size is measured, and the dimensional change rate per 1% relative humidity difference is determined from the results of both. The glass transition temperature (Tg) is measured by using a dynamic viscoelasticity measuring device (DMS200 manufactured by Seiko Denshi Kogyo Co., Ltd.) in a tensile mode while increasing the temperature at a rate of 3 ° C./min, and is calculated from the value of tan σ. .

The polyimide film of the present invention can be produced from a polyamic acid prepared by a polyamic acid synthesis method known to those skilled in the art.

As the organic solvent used in the polymerization step of the present invention, various solvents known to those skilled in the art can be used. For example, it is preferable to use a highly polar solvent having high solubility in polyamic acid, but it is also possible to add a poor solvent to these highly polar solvents. Examples of highly polar solvents include:
Amides such as N, N-dimethylformamide, N, N-dimethylacetamide, pyrrolidones such as N-methyl-2-pyrrolidone, phenol, p-chlorophenol,
Examples thereof include phenols such as o-chlorophenol. Examples of the poor solvent include toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol and the like. The solubility can also be increased by mixing these solvents and appropriately adjusting the solubility parameter.

In the present invention, in order to synthesize polyamic acid, TMHQ having the following structural formula is used as an acid anhydride.

[0023]

[Chemical 1]

And ODPA having the following structural formula

[0025]

[Chemical 2]

PD having the following structural formula as the diamine
A

[0027]

[Chemical 3]

And an ODA having the following structural formula

[0029]

[Chemical 4]

Is used.

The order of addition of each monomer for synthesizing the polyamic acid is not particularly limited, and various methods are possible.
In the solvent, dissolve all the diamines, gradually add tetracarboxylic dianhydride to this to adjust the viscosity as an equivalent weight, and further dissolve the remaining tetracarboxylic dianhydride as it is or in a suitable solvent. In addition, the equivalence ratio is generally made equal, but not limited to this. The properties of the film can be finely controlled depending on the order of addition. Specifically, O
DA and PDA are dissolved in a solvent, while TMH
A method of adding Q and then adding ODPA; or, similarly, two kinds of diamines are dissolved in a solvent and OD is added thereto.
A method of sequentially adding two kinds of acid anhydrides in the order of PA and TMHQ; or a method of similarly dissolving two kinds of diamines and then adding a mixture of two kinds of acid anhydrides; among the two kinds of diamines Either one is dissolved in a solvent, one of the two acid anhydrides is added to this, then another diamine is added, and then another acid anhydride is added, Etc. can be raised. Variations are further increased by adding one kind of diamine in a plurality of steps, and these allow fine adjustment of various characteristics. In particular, when a polyamic acid synthesized by dissolving ODA and PDA in an organic solvent, adding TMHQ, and then adding ODPA was used, the order of addition of acid anhydrides was reversed from that in the reverse order. The polyimide film obtained also has a high Tg and is preferable.

In any case, the total molar amount of the diamine compound and the total molar amount of the acid anhydride compound are set to be substantially the same. Here, the reason why they are "substantially the same" is that if they are completely the same, the degree of polymerization will be excessively increased, and as a result, the solution viscosity will be excessively increased, making it difficult to handle.
The ratio of the total molar amount of diamine compounds and the total molar amount of acid anhydride compounds is 0.95 to 1.05, preferably 0.98.
The range is from 1.02, and it is particularly preferable that the ratio is not 1: 1.

The addition ratio of each monomer is not particularly limited, but TMHQ is preferably contained in all acid anhydrides.
It is more than 0 mol% and 90 mol% or less, and ODPA is
10 mol% or more and less than 100 mol%, PDA is 25 mol% or more and 90 mol% or less in all diamines,
ODA is 10 mol% or more and 75 mol% or less. Particularly preferably, TMHQ is 1 mol% to 90 mol% and ODPA is 10 mol% to 9 mol in the total acid anhydride.
It is 9 mol% or less. Most preferably, in total acid anhydride,
TMHQ is 5 mol% or more and 50 mol% or less, OD
PA is 50 mol% or more and 95 mol% or less, PDA is 50 mol% or more and 90 mol% or less, and ODA is 10 mol% or more and 50 mol% or less in all diamines.

A small amount of a monomer component other than these four types of monomers is added, that is, in the case of a diamine, 10 mol% or less of the whole diamine, and in the case of an acid anhydride, 1% of the whole acid anhydride.
It is also possible to finely adjust the properties of the obtained polyimide film by adding an amount of 5 mol% or less. Although depending on the monomer used, if the amount of the copolymer is generally less than this amount, the hygroscopic property, thermal property, and mechanical property can be maintained at preferable levels. As a monomer used in a small amount, as a diamine, dimethylbenzidine, 2,2'-bis (4-
Examples thereof include aminophenoxyphenyl) propane, 4,4′-bis (4-aminophenoxy) biphenyl, and halogen substitution products thereof such as fluorine. Examples of acid anhydrides include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, and 3 ，
Examples thereof include 3 ′, 4,4′-diphenylsulfone tetracarboxylic acid dianhydride.

The polymerization reaction is not particularly limited as long as it is a temperature generally used for the polymerization reaction of polyamic acid.
The temperature is preferably 60 ° C or lower, and more preferably 40 ° C or lower. At a high temperature, a ring-opening reaction of an acid anhydride group is likely to occur, which may hinder the polyamic acid formation reaction.

The polymerization reaction is preferably carried out in an inert gas such as nitrogen or argon, but may be carried out under other conditions.

The concentration of the polyamic acid in the solution is 5 to 30.
wt%, and more preferably 10 to 25 wt%. If the concentration is lower than this, the amount of solvent increases, and it takes time to dry after the film is produced. If the concentration is higher than this, the viscosity may increase and the processing may become difficult.

The viscosity of the polyamic acid solution is not particularly limited as long as it can be processed into a film, but it is about 1 at 22 ° C.
00 to 10000 poise, preferably 500 to 6
It is 000 poise. If the viscosity is too low, the film characteristics are adversely affected, and it is difficult to stabilize the thickness during processing. On the other hand, if the viscosity is too high, it becomes difficult to stir the solution, and a strong force is required when processing into a film,
It is inconvenient.

The obtained solution of polyamic acid can be formed into a film, and the polyamic acid can be imidized to obtain a polyimide film. Generally, this imidization includes a thermal method of dehydrating by heating and a chemical method of using a dehydrating agent or an imidizing catalyst. Any of these methods may be used, and both the chemical method and the thermal method may be used in combination. A chemical method in which a dehydrating agent and a catalyst are added and heated and dried is more efficient than the thermal method, and excellent characteristics can be imparted to the film. Even when a dehydrating agent or an imidization catalyst is not used, if the four kinds of monomers of the present invention are used, it is possible to achieve the same characteristics by a method such as adding a stretching step in the manufacturing process, but productivity is also improved. From the aspect, the chemical method is preferable.

Such a dehydrating agent is, for example, an aliphatic acid anhydride such as acetic anhydride or an aromatic acid anhydride.

The catalyst used for imidization is pyridine,
and tertiary amines such as α-picoline, β-picoline, γ-picoline, trimethylamine, dimethylaniline, triethylamine and isoquinoline.

Examples of chemical methods for imidization are shown below, but the present invention is not limited thereto. That is, a solution obtained by adding a stoichiometric or more stoichiometric dehydrating agent and a catalytic amount of a tertiary amine to the obtained polyamic acid solution is used as a film, a drum, or an endless belt made of an organic compound such as a support plate or PET. It is cast or coated on to form a film.
It is dried at a temperature of 50 ° C. or lower for about 5 to 90 minutes to obtain a self-supporting polyamic acid polymer coating film. Next, this is peeled off from the support to fix the end portion. After that, 100 ℃
It is imidized by gradually heating to about 500 ° C., cooled, and then removed to obtain a polyimide film.

Examples of thermal imidization include, but are not limited to, steps similar to those of the chemical imidization method described above. That is, the polyamic acid solution is applied to a support plate or P
A film made of an organic compound such as ET or a support such as a drum or an endless belt may be cast or coated to form a film, and heat-treated.

In the production of the film, a thermal deterioration inhibitor may be added to prevent the film from deteriorating during firing. Other additives can be added to prevent deterioration of the film during film production. Examples of the thermal deterioration inhibitor include phosphoric acid-based deterioration inhibitors such as triphenyl phosphate, and benzophenone having a substituent or not having a substituent. Other additives include
Examples include simple metals, organic metal compounds, and glass-based fillers.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0046]

【Example】

Example 1 25.1 g (about 62.5 mol% of total diamine) of PDA and 27.9 g of 750 g of dimethylacetamide in an ice bath in a nitrogen-substituted atmosphere.
g (about 37.5 mol% of total diamine) ODA was dissolved, and 52.5 g of TMHQ (about 3% of total acid anhydride) was dissolved therein.
1 mol%) was gradually added to the reaction mixture with good stirring, followed by 79.4 g of ODPA (about 69 mol% in total acid anhydride).
Was slowly added, and a polyamic acid solution having a porosity of about 2500 poise was measured at 23 ° C.

100 g of this polyamic acid solution was cooled to about 0 ° C., 13.5 g of acetic anhydride and 4.1 g of isoquinoline were added thereto, and the mixture was uniformly stirred. After baking this on a SUS plate, it became 50 μm. It was cast to a predetermined thickness as described above and dried at 125 ° C. for 5 minutes with hot air. After that, peel off the film from the SUS plate, and fix it with 4 pieces 1
1.5 minutes at 70 ℃, 1.5 minutes at 250 ℃, 3 at 350 ℃
Min, heated and dried at 430 ° C. for 3 minutes to obtain a polyimide film. Table 1 shows the results of measuring the tensile elastic modulus, elongation at break, linear expansion coefficient, hygroscopic expansion coefficient, and Tg of this film.

Example 2 20.6 g (about 55 mol% of the total diamine) of PDA and 31.2 g of 750 g of dimethylacetamide in an ice bath under a nitrogen-substituted atmosphere were used.
Dissolve ODA (about 45 mol% in total diamine),
79.4 g of TMHQ (about 50 mo in total acid anhydride)
1%) was gradually added to the reaction mixture with good stirring, followed by ODP.
A53.8 g (about 50 mol% in the total acid anhydride) was gradually added to obtain a polyamic acid solution of about 2500 poise measured at 23 ° C.

This polyamic acid solution was processed in the same manner as in Example 1 to obtain a polyimide film. A characteristic test was conducted in the same manner as in Example 1. The results are shown in Table 1.

(Example 3) Polymerization was performed in the same manner as in Example 1 except that the order of addition of ODPA and TMHQ was reversed, and a polyimide film was prepared in the same manner as in Example 1, and a characteristic test was conducted. The results are shown in Table 1.

[0052]

[Table 1]

(Comparative Examples 1 to 4) In the same manner as in Examples,
The total solid content concentration in the solution is 20 by adding an acid anhydride after dissolving all the diamine components in dimethylacetamide.
%, And the viscosity was 2500 poise. Each component and its mol% are shown in Table 2.
Here, PMDA represents pyromellitic dianhydride,
BPDA represents 3,3'4,4'-biphenyltetracarboxylic dianhydride. A polyimide film was obtained using these polyamic acid solutions in the same manner as in the example, and the results of measuring the properties thereof are shown in Table 2.

[0054]

[Table 2]

[0055]

EFFECTS OF THE INVENTION The polyimide film of the present invention has excellent moisture absorption characteristics not found in conventional polyimide films for bases,
In particular, it has a low hygroscopic expansion, and has high elasticity, but does not fall below the linear expansion coefficient of copper. Therefore, when it is used as a copper-clad substrate or a tape for TAB, extremely excellent warp characteristics can be exhibited. INDUSTRIAL APPLICABILITY The polyimide film of the present invention is excellent in flexibility and heat resistance, and does not impair the properties required as a base polyimide film, so that it can be applied to electronic devices that are becoming more and more fine.

Continued front page    F-term (reference) 4F071 AA60 AA86 AF20Y AF21Y                       AF54 AF62Y AG12 AG28                       AG34 AG36 AH12 BA02 BB02                       BC01                 4J002 CM041 GF00 GQ00 GS01                 4J043 PA06 PA19 QB15 QB26 QB31                       RA06 RA35 SA06 SB03 TA22                       TB03 UA121 UA131 UA132                       UA142 UB121 UB122 UB172                       VA011 VA021 VA022 VA032                       VA041 VA062 XA13 XB35                       YA08 ZA32 ZB11 ZB50

Claims (4)

[Claims] 1. P-phenylene bis (trimellitic acid monoester anhydride), oxydiphthalic dianhydride, p-
A polyimide film produced from a polyamic acid obtained by reacting phenylenediamine and 4,4′-diaminodiphenyl ether in an organic solvent. 2. The p-phenylene bis (trimellitic acid monoester anhydride) is contained in an amount of 1 to 9 with respect to the total acid anhydride.
0 mol%, oxydiphthalic dianhydride is 10-99 mol% based on total acid anhydrides, p-phenylenediamine is 25-90 mol% based on total diamines, 4, 4 '-Diaminodiphenyl ether is 10-75 mol% with respect to all diamines, The polyimide film of Claim 1 characterized by the above-mentioned. 3. The polyimide film according to claim 1, wherein the average linear expansion coefficient at 100 ° C. or higher and 200 ° C. or lower is 15 to 30 ppm, and the tensile elastic modulus is 4.5 to 8.
A polyimide film having 5 GPa, an elongation at break of 20% or more, a hygroscopic expansion coefficient of 10 ppm or less, and a Tg of 200 ° C. or more. 4. 4,4′-Diaminodiphenyl ether and para-phenylenediamine are dissolved in an organic solvent, p-phenylenebis (trimellitic acid monoester anhydride) is added to the organic solvent solution, and then oxydiphthalic acid diester is added. A method for producing a polyimide film, which comprises subjecting a polyamic acid polymer obtained by adding an anhydride to dehydration ring closure using an acid anhydride and a tertiary amine to obtain a polyimide film.