KR101558621B1

KR101558621B1 - Polyimide film

Info

Publication number: KR101558621B1
Application number: KR1020100129175A
Authority: KR
Inventors: 이길남; 원동영; 안찬재; 김성원; 명범영
Original assignee: 에스케이씨코오롱피아이 주식회사
Priority date: 2010-12-16
Filing date: 2010-12-16
Publication date: 2015-10-08
Also published as: WO2012081763A1; KR20120067645A

Abstract

The present invention relates to a polyimide film, and more particularly, to a polyimide film which is excellent in dimensional stability and tear strength and is used as a base film of a product requiring high reliability.

Description

Polyimide film [0002]

The present invention relates to a polyimide film excellent in dimensional stability and tear strength.

Polyimide films are widely used in the fields of electrical / electronic materials, space / aviation and telecommunications due to their excellent mechanical and thermal dimensional stability and their chemical stability properties.

Particularly, the polyimide film is widely used as a flexible circuit substrate material having a minute pattern due to the thinning and shortening of parts, for example, a base film such as TAB or COF.

TAB or COF technology is a technique for sealing an IC chip or an LSI chip, specifically, a technique of forming a conductive pattern on a flexible tape and mounting a chip thereon to seal the flexible tape. The size of the packaged sealing element is small and flexible It is advantageous for simple and light weight of product.

In order to use a polyimide film as a base film for TAB or COF, high dimensional stability is required. This is because dimensional changes may occur due to heat shrinkage during the process of manufacturing TAB or COF bonding the polyimide film in a heated state or cooling process after the sputtering process, or dimensional changes may occur due to residual stress after the etching process. As a result of dimensional change, a position error may occur in the process of bonding IC or LSI chip to TAB or COF.

In addition, the polyimide film undergoes a high temperature treatment process, which causes expansion due to heat. The coefficient of thermal expansion (CTE) is a measure of this degree. If the coefficient of thermal expansion is large, the polyimide film shrinks more than the semiconductor while being cooled after the semiconductor junction at a high temperature, so that stress is applied to the junction portion.

The present invention provides a polyimide film having improved dimensional stability and tear strength due to a network structure of a polymer.

The polyimide film according to one embodiment of the present invention is produced by mixing an aromatic tetracarboxylic acid dianhydride component containing biphenyltetracarboxylic dianhydride or a functional derivative thereof with p-phenylenediamine, diaminodiphenyl ether, Is obtained by imidizing a polyamic acid composed of an aromatic diamine component containing diaminobenzoic acid; The dimensional stability measured according to IPC TM 650 2.2.4A is 0.02% or less; The tear strength measured according to ASTM D 1004 standard may be 3.0 kgf or more.

In this embodiment, the aromatic diamine component may comprise diamine benzoic acid in an amount of at least 3 mol% of the total aromatic diamine component.

In this embodiment, the biphenyltetracarboxylic acid dianhydride or a functional derivative thereof may be contained at 90 mol% or more of the total aromatic tetracarboxylic acid dianhydride component.

In this embodiment, 100 mol% of the aromatic tetracarboxylic acid dianhydride component of biphenyltetracarboxylic acid dianhydride; to 100 mol% of an aromatic diamine component which is 55 to 75 mol% of p-phenylenediamine, 20 to 40 mol% of diaminophenyl ether and 3 to 5 mol% of diamine benzoic acid, can be obtained by imidizing a polyamic acid.

In this embodiment, the imidization may be accompanied by a chemical transformation by a conversion agent comprising an imidization catalyst and a dehydrating agent.

Hereinafter, the present invention will be described in detail.

The present invention relates to an aromatic tetracarboxylic acid dianhydride component comprising a biphenyltetracarboxylic acid dianhydride or a functional derivative thereof and an aromatic diamine component containing p-phenylenediamine, diaminodiphenyl ether and diaminobenzoic acid And more particularly to a polyimide film obtained by imidizing a polyamic acid having a dimensional stability of 0.02% or less; And a tear strength of 3.0 kgf or more.

Here, the dimensional stability is performed according to IPC TM 650 2.2.4A, and the mechanical change direction (TD) / TD (transverse direction) dimensional change rate is measured by processing at 200 ° C for 2 hours. .

The tear strength is measured according to ASTM D 1004 and measured in the MD / TD direction. The crosshead speed is 51mm / min.

Generally, in order to use a polyimide film as a base film for TAB and COF, a wet process, a high-temperature process, and the like are performed. In this process, the polyimide film may have minute dimensional changes due to moisture, heat, etc. In the present invention, it is desired to provide a polyimide film having enhanced dimensional stability and tear strength by strengthening the intermolecular network.

In one embodiment of the present invention, there is provided a polyimide film having a dimensional stability of 0.02% or less as defined above and a tearing strength of 3.5 kgf or more as defined above.

When the polyimide film according to an embodiment of the present invention is applied to a flexible circuit board, particularly, a TAB or COF base film, which is a semiconductor mounting type flexible circuit board, a dimensional change or an adhesive layer separation May not occur.

In this respect, the polyimide film according to an embodiment of the present invention may have a moisture absorption rate of 1.4% or less.

In this case, the moisture absorption rate is measured by cutting a part of the film and storing it in a chamber of 100% RH (relative humidity) atmosphere for 48 hours and then using a thermal gravimetric analysis. It can be calculated by heating the temperature from 35 ° C to 250 ° C at 10 ° C / min and analyzing the change in weight.

When a film absorbs moisture while a polyimide film is being fabricated through a wet process during the process of fabricating a flexible circuit board, a volume expansion occurs to distort the dimensions of the flexible circuit board. Due to the vapor that is vaporized in the high- Which may cause delamination of the adhesive layer.

In this respect, the polyimide film according to one embodiment of the present invention may preferably have a moisture absorption rate of 1.3% or less.

Methods for satisfying the dimensional stability and tear strength within the above-mentioned range are not limited. However, in the method considered in the present invention, as the aromatic tetracarboxylic acid dianhydride component used for producing polyamic acid, A method of containing a carboxylic acid dianhydride or a functional derivative thereof and containing an aromatic diamine component such as p-phenylenediamine, diaminophenyl ether and diaminobenzoic acid.

Particularly preferably, the aromatic diamine component contains diamine benzoic acid in an amount of at least 3 mol% of the total aromatic diamine component, thereby enhancing the dimensional stability and tear strength by strengthening the network structure of the polymer while controlling the viscosity.

Also preferably, the aromatic tetracarboxylic acid dianhydride component contains biphenyltetracarboxylic acid dianhydride or a functional derivative thereof in an amount of 90 mol% or more of the total aromatic tetracarboxylic acid dianhydride component to improve the chemical resistance .

The most preferable polyimide film in terms of satisfying the dimensional stability and tear strength described above comprises 100 mol% of an aromatic tetracarboxylic acid dianhydride component which is biphenyl tetracarboxylic acid dianhydride; a polyamic acid having an aromatic diamine component in an amount of 55 to 75 mol% of p-phenylenediamine, 20 to 40 mol% of diaminodiphenyl ether and 3 to 5 mol% of diaminobenzoic acid, .

Other methods that may be considered to satisfy the dimensional stability and tear strength described above include imidization may involve chemical conversion by a conversion agent comprising an imidization catalyst and a dehydrating agent.

In order to facilitate the understanding of the production of the polyimide film to achieve the present invention, the composition and the film-forming method will be specifically described below, but the present invention is not limited thereto.

[Aromatic tetracarboxylic acid dianhydride]

The aromatic tetracarboxylic acid dianhydrides usable in the present invention include biphenyltetracarboxylic acid dianhydrides such as 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride or a functional derivative thereof, pyromellitic dianhydride Benzenephenone tetracarboxylic acid dianhydride or a functional derivative thereof such as 3,3 ', 4,4'-benzophenonetetracarboxylic acid anhydride, p-phenylene-bis-trimellitic anhydride or its functional derivative, Dianhydride and the like can be used, but it is preferable to use biphenyl tetracarboxylic acid dianhydride in 90 mol% or more of the total aromatic tetracarboxylic acid dianhydride as described above.

Polyimide films containing an excess of biphenyltetracarboxylic dianhydride units exhibit a high elastic modulus value, a low moisture absorption rate and excellent chemical resistance.

[Aromatic diamine component]

The diamines usable in the present invention include p-phenylenediamine and diaminophenyl ethers such as 4,4'-diaminophenyl ether, 3,4-diaminophenyl ether and 2,4-diaminophenyl ether, And diaminobenzoic acid such as 3,5-diaminobenzoic acid.

Preferably, the proportion of p-phenylenediamine in the total diamine is at least 55 mol%, more preferably 55 to 75 mol%, of the total aromatic diamine component. p-Phenylenediamine is a monomer having linearity as compared with diaminophenyl ether and serves to lower the coefficient of thermal expansion of the film. On the other hand, if the content of p-phenylenediamine is high, the flexibility of the film is deteriorated and the film forming ability may be lost.

In this respect, the content of the diaminophenyl ether may be 40 mol% or less, preferably 20 to 40 mol%, of the total aromatic diamine component.

The content of the diaminobenzoic acid in combination may be 3 mol% or more, preferably 3 to 5 mol%, of the total aromatic diamine component. Diaminobenzoic acid plays a role of controlling viscosity and enhancing the intermolecular network structure to improve physical properties such as dimensional stability and tear strength.

[Polyimide film forming method]

Generally, the method of forming a polyimide film is not particularly limited to a person skilled in the art. First, an aromatic tetracarboxylic dianhydride and an aromatic diamine component are reacted with each other using an organic solvent to obtain a polyamic acid solution. At this time, it is preferable to use an aprotic solvent as an amide solvent in general, and examples thereof include N, N'-dimethylformamide, N, N'-dimethylacetamide, N-methyl- Pyrrolidone, and the like, and they may be used in combination as required.

The monomer may be added in the form of powder, lump and solution. In the initial stage of the reaction, the monomer may be added in the form of powder to proceed the reaction.

The weight of the monomers charged in the total polyamic acid solution in the state where the aromatic diamine component and the aromatic tetracarboxylic acid dianhydride are substantially charged in an amount of 10 to 30%, preferably 14 to 20% By weight based on the weight of the polymer. Particularly, it is preferable to proceed with the block polymerization.

It is also possible to control the order of introduction of the monomers so that the polyamic acid as described above contains a large amount of molecular chains whose terminals are amines.

On the other hand, a filler may be added to the polyimide film to improve various properties such as sliding properties, thermal conductivity, conductivity, and corona resistance. The kind of the filler can not be limited, but preferred examples thereof include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

The particle size of the filler varies depending on the thickness and type of the film, and the surface of the filler may be modified. The average particle diameter of the filler is preferably 0.1 to 100 mu m, more preferably 0.1 to 3 mu m.

The amount of the filler to be added is not particularly limited, and may vary depending on the film to be modified, the type and particle size of the particles to be modified, the particle surface, and the like. The amount of the filler to be added is preferably in the range of 0.04 to 3% based on the solid content of the polyamic acid solution after polymerization. If the amount of the filler added is more than the above range, the physical properties of the polyimide film may be impaired.

The input method can be added at the beginning of the reaction or after the reaction is finished. Alternatively, the catalyst may be added in a catalyst mixing process to prevent contamination of the reactor, so that the method and timing of the addition are not particularly limited.

The resulting polyamic acid solution may be mixed with a conversion agent, preferably an imidization catalyst and a dehydrating agent, and then applied to the support. Examples of the catalyst to be used include tertiary amines, and dehydrating agents include anhydrous acids. Examples of anhydrous acid include acetic anhydride, and tertiary amines include isoquinoline, beta-picoline, pyridine and the like.

The amount of anhydrous anhydride may be calculated in terms of the molar ratio of the o-carboxylic amide functional group in the polyamic acid solution, and is preferably 1.0 to 5.0 mol.

The amount of the tertiary amine may be calculated in terms of the molar ratio of the o-carboxylic amide group in the polyamic acid solution, and it is suitably applied in the range of 0.2 to 3.0 molar ratio.

The conversion agent can be introduced in the form of an anhydrous / amine mixture or an anhydrous / amine / solvent mixture.

The film applied on the support is gelled on the support by dry air and heat treatment. The gelation temperature of the coated film is preferably 100 to 250 ° C, and a glass plate, an aluminum foil, a circulating stainless belt, a stainless steel drum, or the like may be used as the support.

The treatment time required for the gelation varies depending on the temperature, the type of the support, the amount of the polyamic acid solution applied, and the mixing conditions of the conversion agent, and is not limited to a fixed time, but is preferably in the range of 5 minutes to 30 minutes It is good.

The gelled film is separated from the support and heat treated to complete drying and imidization. The heat treatment temperature is in the range of 100 ~ 600 ℃ and the treatment time is 1 ~ 30 minutes. The gelled film is fixed to the support at the time of heat treatment and proceeds. The gel film can be fixed using a pin type frame or using a clip type.

The residual volatile component of the film after the heat treatment is 5% or less, preferably 3% or less.

The heat-treated film is heat-treated under a constant tension to remove residual stress inside the film. Tension and temperature conditions are correlated with each other, so the tension conditions may vary with temperature. The temperature is preferably maintained between 100 and 600 ° C, and the tension is preferably maintained at 50 N or less, and the time is maintained between 1 minute and 1 hour.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples.

Example One

820g of N, N'-dimethylformamide (DMF) was added as a solvent to the 2L jacket reactor. 20.5 g of p-phenylenediamine (p-PDA) and biphenyltetracarboxylic dianhydride (BPDA) were placed at a temperature of 30 캜. The mixture was stirred for about 30 minutes to confirm the completion of the reaction, and then diaminophenyl ether (ODA) was added. After completion of the reaction, p-phenylenediamine (p-PDA) was added. After completion of the addition, the mixture was stirred for 1 hour while maintaining the temperature at 30 ° C to block polymerization.

Thereafter, diaminobenzoic acid (DABA) solution was added and stirred. At this time, the diaminobenzoic acid solution was prepared at a concentration of 5% using DMF as a solvent.

The completed polyamic acid solution has a solids content of 15 wt% and a viscosity of 2,000 poise. The molar ratios of the input monomers are BPDA 100%, ODA 35%, PDA 62% and DABA 3%.

100 g of the polyamic acid solution and 30 g of the conversion agent solution (5.9 g of isoquinoline, 14 g of anhydrous acetic acid, and 10.1 g of DMF) were uniformly stirred and coated on a stainless steel plate, cast to 250 탆 and dried with hot air at 150 캜 for 5 minutes The film was peeled off from the stainless steel plate and fixed to the frame with a pin.

The frame with the film fixed was placed in a vacuum oven and slowly heated from 100 ° C to 350 ° C for 30 minutes, then slowly cooled to separate the film from the frame. The thickness of the finally obtained film is 38 mu m.

Examples 2 to 6

A polyimide film was prepared in the same manner as in Example 1 except that the polyimide film was prepared by polymerizing the polyamic acid in a monomer composition ratio as shown in Table 1 below.

Example 7

850 g of N, N'-dimethylformamide (DMF) was added as a solvent to a 2 L jacket reactor. 20.6 g of p-phenylenediamine (p-PDA), biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) were placed at 35 ° C. The mixture was stirred for about 30 minutes to confirm the completion of the reaction, and then diaminophenyl ether (ODA) was added. After completion of the reaction, p-phenylenediamine (p-PDA) was added. After completion of the addition, the mixture was stirred for 2 hours while keeping the temperature at 40 ° C to perform block polymerization.

The completed polyamic acid solution has a solids content of 15 wt% and a viscosity of 1,800 poise. The molar ratio of the charged monomers is 95 mol% of BPDA, 5 mol% of PMDA, 35 mol% of ODA, 62 mol% of PDA and 3 mol% of DABA.

The frame with the film fixed was placed in a vacuum oven and slowly heated from 100 ° C to 350 ° C for 30 minutes, then slowly cooled to separate the film from the frame.

Comparative Example One

A polyimide film was prepared in the same manner as in Example 1 except that paraphenylenediamine (PPD) was used instead of diaminobenzoic acid (DABA) in polyamic acid polymerization.

Comparative Example 2

830g of N, N'-dimethylformamide (DMF) was added as a solvent to the 2L jacketed reactor. 23.1 g of p-phenylenediamine (p-PDA) and 24.2 g of diaminophenyl ether (ODA) were added. After confirming that the solution was dissolved, biphenyltetracarboxylic dianhydride (BPDA) 101.6 g. The mixture was stirred for about 30 minutes to confirm that the reaction had been completed, and the mixture was stirred for 1 hour while maintaining the temperature at 30 캜.

Thereafter, 22.4 g of a paraphenylenediamine (PPD) solution was added and stirred, and the addition was completed when the final viscosity was reached. At this time, the paraphenylenediamine (PPD) solution was prepared at a concentration of 5% using DMF as a solvent.

The completed polyamic acid solution has a solids content of 15 wt% and a viscosity of 1800 poise. The molar ratios of the input monomers are BPDA 100%, ODA 35%, and PDA 65%.

The polyamic acid solution was applied to a stainless steel plate, cast to 250 μm, dried with hot air at 120 ° C. for 10 minutes, and then the film was peeled off from the stainless plate and fixed to the frame.

The tensile modulus, coefficient of linear expansion and tearing strength of the films prepared in Examples and Comparative Examples were measured as described below, and the results are shown in Table 2.

(1) Tensile modulus

Tensile modulus was measured by testing three times in accordance with ASTM D 882 using a standard Instron testing apparatus.

(2) Coefficient of linear expansion

A part of the film-finished sample was cut to a width of 4 mm and a width of 30 mm and a coefficient of thermal expansion was measured using a TA mechanical mechanical apparatus Q400. The sample was placed on a quartz hook and heated to 30 ° C to 420 ° C at 10 ° C / min in a nitrogen atmosphere after a force of 0.010 N was applied. The thermal expansion coefficient values were obtained within the range of 50 ° C to 200 ° C

(3) Tear strength

The tear strength was measured by the ASTM D 1004 method.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 BPDA 100 100 100 100 100 100 95 100 100 PMDA - - - - - - 5 - - PDA 62 67 69 72 65 70 62 65 65 ROOM 35 30 28 25 30 25 35 35 35 DABA 3 3 3 3 5 5 3 - -

Example 1 Example 2 Example
3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Tensile modulus
(GPa) 5.4 5.7 6.0 6.2 5.5 6.2 5.5 5.4 5.1 Coefficient of linear expansion
(ppm /) 14 13 10 9 14 9 14 14 18 Phosphorus strength
(kgf) 3.0 3.1 3.0 3.1 3.5 3.2 3.1 2.8 2.7

From the results shown in Table 2, it can be seen that the polyimide films obtained in Examples 1 to 7 have excellent tensile modulus, low coefficient of linear expansion, and excellent tear strength.

On the other hand, the polyimide film obtained by Comparative Examples 1 and 2 had lower tensile modulus and tear strength and higher coefficient of linear expansion than the polyimide film obtained by Examples 1 to 7.

Claims

Which comprises an aromatic tetracarboxylic acid dianhydride component comprising biphenyltetracarboxylic acid dianhydride or a functional derivative thereof and an aromatic diamine component comprising p-phenylenediamine, diaminodiphenyl ether and diaminobenzoic acid, Obtained by imidizing a mixed acid;
The diaminobenzoic acid is contained in an amount of 3 to 5 mol% in a total of 100 mol% of the aromatic diamine;
A polyimide film having a dimensional stability measured according to IPC TM 650 2.2.4A of 0.02% or less and a tear strength measured according to ASTM D 1004 of 3.0 kgf or more.

delete

The polyimide film according to claim 1, wherein the biphenyltetracarboxylic acid dianhydride or a functional derivative thereof is contained at 90 mol% or more of the total aromatic tetracarboxylic acid dianhydride component.

2. The aromatic tetracarboxylic acid dianhydride composition according to claim 1, wherein the aromatic tetracarboxylic acid dianhydride component is biphenyl tetracarboxylic dianhydride; the polyamic acid is obtained by imidizing a polyamic acid having an aromatic diamine component of 55 to 75 mol% of p-phenylenediamine, 20 to 40 mol% of diaminodiphenyl ether and 3 to 5 mol% of diaminobenzoic acid, Lt; / RTI >

The polyimide film according to claim 1, wherein the imidization is accompanied by a chemical conversion by a conversion agent comprising an imidation catalyst and a dehydrating agent.