JP2000290372A - Polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent polyimide film which combines a high elasticity, a linear expansion coefficient equivalent to that of cupper foil and a low moisture-absorbent (hygroscopic) expansion coefficient. SOLUTION: The polyimide film is prepared from a polyamide acid obtained by reacting, in an organic solvent, p-phenylenebis-(trimellitic acid monoester anhydride),2,2-bis(4-hydroxyphenyl)-propanedibenzoate-3,3',4,4'-tetrac arboxylic acid dianhydride, p-phenylenediamine, and 4,4'-diaminobenzanilide.

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 a good balance of physical properties and capable of providing low warpage and high dimensional stability in a product bonded to a metal, particularly copper.

[0002]

2. Description of the Related Art Polyimide films have heat resistance, insulation, solvent resistance, low-temperature resistance and the like, and are widely used as components for computers and IC-controlled electric and electronic devices.

In recent years, with the miniaturization and thinning of computers and IC-controlled electric and electronic devices, wiring boards and ICs have been developed.
Packaging materials are also required to be smaller and thinner. For this reason, the wiring patterns applied to these become finer, and it is necessary that polyimide films used for flexible wiring boards, TAB carrier tapes, and the like have small dimensional changes due to heating, pulling, and moisture absorption. Further, as the thickness of the material is reduced, it is necessary to maintain the “strain” of the entire laminate and to stabilize the processing steps.

In order to satisfy such a need, it is desired that the polyimide film has a small linear expansion coefficient, a high elastic modulus and a low moisture absorption expansion coefficient. However, when a flexible wiring board or an IC package is manufactured, a polyimide film and a copper foil are bonded and processed, so that the coefficient of linear thermal expansion of the film is preferably not significantly different from that of copper. That is, if the linear expansion coefficient of the polyimide film is significantly different from that of the copper foil, the bonded product is warped, making it difficult to process, and as a result, the overall dimensional accuracy and yield are reduced.

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

In order to realize a relatively high elastic modulus but not to lower the coefficient of linear expansion too much, a monomer having a relatively rigid structure is produced by a thermal curing method without using a chemical imidizing agent. In some cases, a method of reducing the orientation in the plane direction is adopted, but the heat curing method has a disadvantage that the required heating time is longer than that of the chemical curing method and the productivity is inferior. Furthermore, when a rigid and highly linear monomer is used, the flexibility of the film is generally impaired, and it may be difficult to bend, which is one of the advantages as a flexible wiring board or the like. .

In applications such as semiconductor packages, it is required that the water absorption is as low as possible from the viewpoint of reliability of the semiconductor, and that the coefficient of hygroscopic expansion is also low from the viewpoint of dimensional stability. To reduce the water absorption and the coefficient of hygroscopic expansion, it is effective to reduce the amount of imide groups in the molecular structure. For this reason, a long-chain monomer containing a plurality of bending groups in the main chain is often used. However, this results in a decrease in elastic modulus and an excessive increase in coefficient of linear expansion, and sacrifices dimensional stability.
In an extreme case, the polymer exhibits a thermoplastic property having a Tg at a low temperature of, for example, 200 ° C. or less, and is not suitable for use as a base film. When a linear and long monomer is used, packing of molecular chains becomes difficult, and sufficient toughness cannot be exhibited, and in some cases, it becomes difficult to form a film itself.

As described above, there are many points to be considered as characteristics of the polyimide film, in addition to the high elastic modulus, the low linear expansion coefficient, and the decrease in water absorption. However, it is particularly difficult to obtain a polyimide film having a plurality of good characteristics, such as sacrificing other characteristics when trying to satisfy one of the characteristics.

[0009]

Accordingly, the present inventors have solved the above-mentioned problems, and have developed characteristics such as a high elastic modulus, a linear expansion coefficient close to copper, sufficient toughness, a low water absorption coefficient and a moisture absorption expansion coefficient. The inventors of the present invention have conducted intensive studies on the production of a polyimide film suitable for a flexible printed circuit board or a TAB film having a thin wiring, and as a result, the present invention has been reached.

[0010]

SUMMARY OF THE INVENTION In view of the above-mentioned requirements, the present inventors have found a special case in which a polyimide film having a specific composition can achieve a high balance of various properties.

The gist of the polyimide film of the present invention is p-phenylenebis (trimellitic acid monoester anhydride), 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ', 4 , 4'-tetracarboxylic dianhydride, paraphenylenediamine, 4,
It is to be produced from a polyamic acid obtained by reacting 4'-diaminobenzanilide in an organic solvent.

In such a polyimide film, the above p
-Phenylene bis (trimellitic acid monoester anhydride) is 40 to 99 mol% based on the total acid anhydride;
2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride is 1 to 60 mol% based on the total anhydride, and paraphenylenediamine is 0 to 100 mol% of the total diamine and 4,4'-diaminobenzanilide are 0 to 100 mol% of the total diamine.

In such a polyimide film, 100
The average linear expansion coefficient between 200 ° C and 200 ° C is 15-30 pp
m / ° C., a tensile modulus of 5.5 to 8.5 GPa, and a coefficient of hygroscopic expansion of 10 ppm / RH% or less.

[0014] Preferably, in the method for producing a polyimide film of the present invention, the dehydration ring closure may be performed in the presence of an imidating agent between an acid anhydride and a tertiary amine.

The p-phenylenebis (trimellitic acid monoester anhydride) monomer (hereinafter referred to as TMHQ) is
In combination with paraphenylenediamine (hereinafter referred to as p-PDA), it has a rod-like structure, exhibits high elasticity of the film, has an ester bond on the main chain structure, and is slightly flexible thermally. The coefficient of linear expansion does not decrease extremely as compared with the case where pyromellitic acid is used. Further, the ester bond has the effect of relaxing the polarization of the imide ring, lowering the water absorption rate and decreasing the moisture expansion rate. However, TMHQ, in combination with p-PDA,
It is structurally too hard, still has a low coefficient of linear expansion, and has insufficient toughness. Even when a flexible diamine compound such as diaminodiphenyl ether is copolymerized, the coefficient of linear expansion is still too low to obtain a certain elastic modulus, and it is difficult to balance the two.

2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4, which is frequently used for synthesizing a thermoplastic polyimide film
When 4'-tetracarboxylic dianhydride (hereinafter referred to as ESDA) is used, the same as when TMHQ is used, ES
Due to the effect of the ester bond contained in DA to relax the polarization of the imide ring, a polyimide film having a low water absorption and a low coefficient of moisture expansion can be obtained. However, even in combination with rigid diamines such as p-PDA and 4,4'-diaminobenzanilide (hereinafter, referred to as DABA), the coefficient of linear expansion is very large at 60 to 70 ppm / ° C. The rate is also lower. Therefore, the configuration of the present invention, in which TMHQ is further copolymerized for maintaining a suitable linear expansion coefficient and high elasticity without inconvenience in combination with copper while maintaining the moisture absorption characteristics when ESDA is used, is very effective. It is. That is, according to the present invention, a well-balanced polyimide film having characteristics of a high modulus of elasticity, an appropriate linear expansion coefficient without a disadvantage in combination with copper, and a low hygroscopic expansion coefficient can be obtained.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The term "monomer" in the present invention is defined as
It refers to either monomeric diamine or tetracarboxylic dianhydride.

As the characteristics of the polyimide film, the tensile modulus here means a value measured according to ASTM-D882. The average linear expansion coefficient is TMA81 manufactured by Rigaku Denki Co., Ltd.
Using a 40, the temperature is increased at a rate of 10 ° C. per minute in the presence of nitrogen, and the value at 100 ° C. to 200 ° C. is measured and determined. The coefficient of hygroscopic expansion is determined by applying a minimum load (5 mm × 2 mm) so that the polyimide film does not sag.
For a 0 mm sample, about 3 g) and a humidity of 30R
Humidity was adjusted to H%, moisture was absorbed until it was completely saturated, and the dimensions were measured. Then, the humidity was adjusted to 90 RH%, and the moisture was similarly saturated and absorbed. Then, the dimensions were measured.
Calculate the dimensional change rate around

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 include phenols such as o-chlorophenol. Examples of the poor solvent include toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol and the like. By mixing these solvents and appropriately adjusting the solubility parameter, the solubility can be increased.

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

[0022]

Embedded image And ESDA with the following structural formula

[0023]

Embedded image Is used.

In the present invention, in order to synthesize polyamic acid, p-PD having the following structural formula is used as a diamine.
A

[0025]

Embedded image DABA with the following structural formula

[0026]

Embedded image At least one selected from the group consisting of:

The order of adding each monomer for synthesizing the polyamic acid is not particularly limited, and various methods can be used.
In the solvent, dissolve all the diamine, gradually add tetracarboxylic dianhydride to this and adjust the viscosity as an approximately equivalent, and further dissolve the remaining tetracarboxylic dianhydride as it is or in an appropriate solvent. In addition, it is common practice to make equivalence ratios equal, but not limited to this. Depending on the order of addition, the properties of the film can be finely controlled. Specifically, D
ABA and p-PDA, or DABA or p-PD
A is dissolved in a solvent, and TMHQ is added thereto.
Thereafter, a method of adding ESDA; or a method of dissolving DABA and p-PDA, or DABA or p-PDA in a solvent, and sequentially adding two acid anhydrides to ESDA and TMHQ in this order; or A method in which two diamines are dissolved and a mixture of two acid anhydrides is added thereto; one of the two diamines is dissolved in a solvent, and the two acid anhydrides are added thereto. One of them can be added, and then another diamine can be added, and then another acid anhydride can be added. Variations are further increased by adding one kind of diamine in a plurality of steps, and these allow fine adjustment of various characteristics. Especially DA
BA and p-PDA, or DABA or p-PDA
Is dissolved in an organic solvent, and TMHQ is added thereto, followed by addition of ESDA.In the case of using a polyamic acid synthesized by the procedure described above, a polyimide obtained by adding the acid anhydride in the reverse order is obtained. Films are preferred.

In any case, the total molar amount of the diamine compound and the total molar amount of the acid anhydride compound are used so as to be substantially the same. Here, the term "substantially the same" is used because the degree of polymerization is excessively increased if the two are completely the same, and as a result, the solution viscosity is excessively increased and the handling becomes difficult.
The ratio of the total amount of the diamine compound to the total amount of the acid anhydride compound is 0.95 to 1.05, preferably 0.98.
To 1.02, and particularly preferably not 1: 1.

The proportion of each monomer to be added is not particularly limited, but preferably, in all the acid anhydrides, TMHQ is
40 mol% or more and 99 mol% or less;
Mol% or more and 60 mol% or less, and the ratio of p-PDA and DABA does not need to be limited with respect to the diamine component, that is, both are 0 mol% or more and 100 mol% or less in all diamines. Good properties are exhibited even when used. With respect to the acid dianhydride component, particularly preferably,
TMHQ in the total acid anhydride is 50 mol% or more and 90 mol%.
Or less, and the ESDA is 10 mol% or more and 50 mol% or less.

A small amount of a monomer component other than these four monomers is added, that is, 10% by mole or less of the total amount of the diamine in the case of the diamine, and 1% of the total amount of the acid anhydride in the case of the acid anhydride.
By adding an amount of 5 mol% or less, it is possible to finely adjust the characteristics of the obtained polyimide film. Although it depends on the monomer used, if the copolymerization is approximately equal to or less than this amount, the moisture absorption properties, thermal properties, and mechanical properties can be maintained at preferable levels. Examples of the monomer used in a small amount include dimethylbenzidine, 4,4′-diaminodiphenyl ether, 2,2′-bis (4-aminophenoxyphenyl) propane, 4,4′-bis (4-aminophenoxy) biphenyl, Further, halogen-substituted products such as fluorine may be used. Examples of the acid anhydride include oxydiphthalic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic acid Examples thereof include dianhydride and 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride.

The polymerization reaction is not particularly limited as long as it is a temperature generally used for a polyamic acid polymerization reaction.
The temperature is preferably 60 ° C. or lower, more preferably 40 ° C. or lower. When the temperature is high, a ring opening reaction of the acid anhydride group is likely to occur, which may inhibit the polyamic acid generation 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%, more preferably 10 to 25 wt%. If the concentration is lower than this, the solvent increases, and it takes time to dry the film after production. If the concentration is higher than this, the viscosity may increase and processing may be difficult.

The viscosity of the polyamic acid solution is not particularly limited as long as it can process a film.
About 00 to 10000 poise, preferably 500 to 60
00 poise. If the viscosity is too low, the properties of the film are adversely affected, and it is also difficult to stabilize the thickness during processing. On the other hand, if the viscosity is too high, stirring of the solution becomes difficult, and a strong force is required when processing into a film, which is inconvenient.

The resulting polyamic acid solution is formed into a film, and the polyamic acid is imidized to obtain a polyimide film. In general, the imidation includes a thermal method of dehydration by heating and a chemical method using a dehydrating agent or an imidization catalyst. Any of these methods may be used, and both the chemical method and the thermal method may be used in combination. According to a chemical method in which a dehydrating agent and a catalyst are added to heat and dry, a film is more efficient than a thermal method, and excellent characteristics can be imparted to a film. Even when a dehydrating agent or an imidization catalyst is not used, if the four types of monomers of the present invention are used, the same properties can be realized by a method such as inserting a stretching step in the production process. In view of this, a chemical method is preferable.

Such dehydrating agents include, for example, aliphatic acid anhydrides such as acetic anhydride, aromatic acid anhydrides and the like.

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

The following are examples of chemical methods for imidization, but the present invention is not limited thereto. That is, a solution obtained by adding a dehydrating agent having a stoichiometric amount or more and a catalytic amount of a tertiary amine to the obtained polyamic acid solution is applied to a support plate, a film made of an organic compound such as PET, a drum, or an endless belt. Into a film by casting or coating
It is dried at a temperature of 50 ° C. or less 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. Then 100 ° C
It is imidized by gradually heating it to about 500 ° C., and after cooling, it is removed from it to obtain a polyimide film.

Examples of the imidization by a thermal method include, but are not limited to, the same steps as in the chemical imidization method described above. That is, the polyamic acid solution is added to the support plate or P
The film may be cast or coated on a support such as a film, a drum or an endless belt made of an organic compound such as ET, and may be subjected to a heat treatment.

In the production of the film, a thermal deterioration inhibitor may be further added to prevent the film from deteriorating during firing. Other additives can be added to prevent the film from deteriorating during the production of the film. Examples of the thermal deterioration inhibitor include a phosphoric acid-based deterioration inhibitor such as triphenyl phosphate, and a benzophenone having or not having a substituent. Other additives include
A simple metal, an organometallic compound, a glass-based filler, or the like can be used.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0042]

(Example 1) 34.9 g (100 mol% in total diamine) of p-PDA was dissolved in 800 g of dimethylacetamide in an ice bath in a nitrogen-substituted atmosphere,
This was mixed with 81.4 g of TMHQ (about 55 mo in total anhydride).
1%) was gradually added, and the mixture was thoroughly stirred and reacted.
83.7 g of A (about 45 mol% in the total acid anhydride) was gradually added to obtain a polyamic acid solution of about 2500 poise by measurement at 23 ° C.

100 g of this polyamic acid solution was cooled to about 0 ° C., and 13.5 g of acetic anhydride and 4.1 g of isoquinoline were added thereto, and the mixture was stirred uniformly and fired on a SUS plate to a thickness of 50 μm. It was cast to a predetermined thickness as described above and dried with hot air at 125 ° C. for 5 minutes. Thereafter, the film was peeled off from the SUS plate, and the four pieces were fixed and heated and dried at 170 ° C. for 1.5 minutes, 250 ° C. for 1.5 minutes, 350 ° C. for 3 minutes, and 430 ° C. for 3 minutes. A film was obtained. Table 1 shows the results of measurement of the tensile modulus, linear expansion coefficient, and moisture expansion coefficient of this film. Example 2 61.5 g (100 mol% in total diamine) of DABA was dissolved in 800 g of dimethylacetamide under an ice bath in a nitrogen atmosphere, and TM was added thereto.
68.2 g of HQ (about 55 mol% in the total acid anhydride) was gradually added, and the mixture was thoroughly stirred and reacted.
g (about 45 mol% in the total acid anhydride) was gradually added, and 2 g
As a result of measurement at 3 ° C., a polyamic acid solution of about 2500 poise was obtained.

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

[0045]

[Table 1] (Comparative Examples 1 to 4) A method of dissolving all diamine components in dimethylacetamide and then adding an acid anhydride in the same manner as in the example. The solution has a total solid concentration of 20% and a viscosity of 2500 poise. The polymerization reaction was carried out as described above. Table 2 shows the components and their mol%. Where ODA
Represents 4,4′-diaminodiphenyl ether. A polyimide film was obtained using these polyamic acid solutions in the same manner as in the examples, and the properties were measured. Table 2 shows the results.

[0046]

[Table 2]

[0047]

As described above, the polyimide film of the present invention has excellent moisture absorbing properties which are not found in the conventional base polyimide film,
In particular, it has a low hygroscopic expansion and high elasticity, but does not fall below the coefficient of linear expansion of copper. Therefore, when used as a copper-clad base or TAB tape, it can exhibit extremely excellent warpage characteristics. The polyimide film of the present invention is excellent in flexibility and heat resistance, and does not impair the characteristics required as a base polyimide film, so that it can be used for electronic devices that are increasingly miniaturized.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA60 AH13 BB02 BC01 4J043 PA06 PA08 PA19 QB15 QB26 QB31 RA35 SA06 SB01 SB03 TA22 TB03 UA121 UA131 UA142 UA672 UB172 UB221 VA011 VA021 VA032 VA041 VA062 XA11 ZA11 ZA11ZA

Claims (3)

[Claims] 1. A p-phenylenebis (trimellitic acid monoester anhydride), 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4,4′-
Tetracarboxylic dianhydride, paraphenylenediamine,
A polyimide film produced from a polyamic acid obtained by reacting 4,4'-diaminobenzanilide in an organic solvent. 2. The p-phenylenebis (trimellitic acid monoester anhydride) is present in an amount of from 40 to 40% based on the total acid anhydride.
99 mol%, and 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride is 1 to 6 with respect to the total anhydride.
2. The composition according to claim 1, wherein 0 mol%, paraphenylenediamine is 0 to 100 mol% with respect to all diamines, and 4,4′-diaminobenzanilide is 0 to 100 mol% with respect to all diamines. 3. Polyimide film. 3. The polyimide film according to claim 1, wherein an average linear expansion coefficient at 100 ° C. or more and 200 ° C. or less is 15-30 ppm / ° C., and a tensile modulus is 5.5-3.5.
A polyimide film having 8.5 GPa and a coefficient of hygroscopic expansion of 10 ppm / RH% or less.