KR20090051886A - Polyimide film - Google Patents

Abstract

The present invention is based on aromatic dianhydride containing pyromellitic acid dianhydride (PMDA) and aromatic diamine containing p-phenylenediamine (p-PDA) as a main raw material, based on the film thickness of 5 ~ 100㎛ By providing a polyimide film having an average linear expansion coefficient of 7.0 ppm / ° C. or less measured at 50 to 200 ° C. according to TMA-Method, a polyimide film having excellent thermal stability and low moisture absorption can be provided.

Description

Polyimide film {Polyimide film}

The present invention relates to a polyimide film, and more particularly, to a polyimide film excellent in heat stability and dimensional stability.

In general, the polyimide (PI) resin refers to a high heat-resistant resin prepared by solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to produce a polyamic acid derivative, and then imidation by ring dehydration at a high temperature. In order to prepare a polyimide resin, pyromellitic acid dianhydride (PMDA) or biphenyl tetracarboxylic dianhydride (BPDA) or the like is used as an aromatic dianhydride component, and oxydianiline (ODA) is used as an aromatic diamine component. ), p-phenylene diamine (p-PDA), m-phenylene diamine (m-PDA), methylenedianiline (MDA), bisaminophenylhexafluoropropane (HFDA) and the like are used.

Such polyimide resins are insoluble and insoluble ultra high heat resistant resins, and have excellent properties such as heat oxidation resistance, heat resistance, radiation resistance, low temperature characteristics, chemical resistance, and the like. Used in a wide range of electronic materials, such as insulating coatings, insulating films, semiconductors, electrode protective films of TFT-LCDs, and recently, display materials such as optical fibers and liquid crystal alignment films and conductive fillers in films or coated on surfaces to be used for transparent electrode films. It is becoming.

In particular, there is a COF (Chip On Film) process as a typical process for manufacturing semiconductor packaging, printed circuit board, and the like. This generally uses a two-layer flexible copper clad laminate (FCCL) consisting of a two-layer structure in which copper foil is deposited and plated on a base film layer, and the copper foil lead is formed after patterning the FCCL. Connect to the printed wiring board and the semiconductor chip. At this time, a polyimide film is used for the base film for the purpose of improving the slidability and flexibility.

However, in general, since a polyimide film having high bendability is high in thermal expansion property, when such a polyimide film is used as a base film, there is a problem that connection failure may occur due to a difference in thermal expansion with a semiconductor to be connected. Therefore, it was difficult to use in the field which requires thermal dimensional stability.

In addition, the polyimide film has a weak disadvantage in moisture. As the drying and moisture absorption are repeated in the COF and FPC (Flexible Printed Circuit) processing processes, dimensional changes may occur, which requires precise work. Since process defects may occur in the semiconductor process, it has been difficult to use in fields requiring dimensional stability.

Therefore, the present invention is to provide a polyimide film having excellent thermal stability.

In another aspect, the present invention is to provide a polyimide film having a low moisture absorption.

In addition, the present invention is to provide a substrate for a display device having excellent thermal stability and low moisture absorption rate excellent in dimensional stability.

Therefore, the present invention is a dianhydride containing pyromellitic acid dianhydride (PMDA) and a diamine containing p-phenylenediamine (p-PDA) as a main raw material as a preferred embodiment, the film thickness of 5 ~ 100 It provides a polyimide film having an average linear expansion coefficient of 7.0 ppm / ° C. or less measured at 50 to 200 ° C. according to TMA-Method based on μm.

Polyimide film according to the embodiment may have a moisture absorption of 1.4% or less.

Polyimide film according to the embodiment is-, -O-, -CO-, -NHCO-, -S-, -SO _2- , -CO-O-, -CH _2- , -C ( CH ₃ ) It may further comprise a soft dianhydride or a soft diamine containing a ₂ -chain.

Polyimide film according to the embodiment may be to include a repeating unit of the formula (1) and formula (2).

Formula 1

Formula 2

When the polyimide film according to the embodiment has a total dianhydride component of 100 mol%, pyromellitic dianhydride (PMDA) is contained 30 mol% to 70 mol%, the total diamine component to 100 mol% In one case, 30 mol% or more of p-phenylenediamine (p-PDA) may be included.

In another aspect, the present invention is to provide a substrate for a display device comprising the polyimide film.

The present invention can provide a polyimide film having excellent thermal stability.

In addition, the present invention can provide a polyimide film having a low moisture absorption.

In addition, the present invention can provide a display device substrate having excellent thermal stability and low moisture absorption rate, excellent in dimensional stability.

Hereinafter, the present invention will be described in more detail.

The polyimide film of this invention is formed from the polyimide which imidated the polyamic acid synthesize | combined from aromatic diamine and aromatic dianhydride as a main raw material. Among these, the aromatic dianhydride includes at least pyromellitic acid dianhydride (PMDA), and the aromatic diamine includes at least p-phenylenediamine (p-PDA). It is preferable that the average linear expansion coefficient measured at 50-200 degreeC according to TMA-Method as a reference | standard is 7.0 ppm / degree C or less.

By satisfying the conditions of the coefficient of linear expansion, the thermal expansion at the semiconductor mounting temperature is not great, and when used as a film for FPC or COF, excellent dimensional stability, process defects can be improved.

Moreover, it is preferable that the moisture absorption is 1.4% or less of the polyimide film of this invention. By satisfying these conditions, the dimensional change caused by the hygroscopic expansion in the process conditions can be suppressed.

The polyimide film of the present invention is formed of a polyimide obtained by imidizing a polyamic acid synthesized from aromatic diamine and aromatic dianhydride as a main raw material, and at this time, in addition to the main raw material, acid components other than aromatic dianhydride and aromatic diamines. Other diamine components may be used.

The polyimide film according to the preferred embodiment of the present invention essentially includes pyromellitic acid dianhydride (PMDA) as a dianhydride component in order to satisfy the above linear expansion coefficient and moisture absorption rate, the content of which is particularly Although not limited, Preferably it is preferable to contain 30 mol%-70 mol% of pyromellitic-acid dianhydride, when the total dianhydride component is 100 mol%. In addition, p-phenylenediamine (p-PDA) is essentially included as the diamine component, but the content thereof is not particularly limited, but when the total diamine component is 100 mol%, at least 30 mol% of p-phenylenediamine is used. It is preferable to include.

In particular, the polyimide film according to the embodiment is-, -O-, -CO-, -NHCO-, -S-, -SO _2- , -CO-O-, -CH _2- , -C between the aromatic rings It may further include a soft dianhydride or a soft diamine containing a chain such as (CH ₃ ) _2- .

Specific examples of such soft dianhydrides include biphenyl tetracarboxylic dianhydride (BPDA), benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), bisphenol Adianhydride ( BPADA), ethylene glycol bis (anhydro trimellitate) (TMEG), diphenylsulfontetracarboxylic dianhydride (DPSDA), biscarboxyphenyl dimethyl silane dianhydride (SiDA), bis dicarboxyphenoxy diphenyl Sulfide dianhydride (BDSDA), sulfonyl diphthalic hydride (SO ₂ DPA), isopropylidenediphenoxy bis phthalic anhydride (6HBDA), and the like, but are not particularly limited. One type of such ductile dianhydride may be used, or two or more types thereof may be used in appropriate combination. The content is also not particularly limited, but is preferably 0 to 70 mol% when the total dianhydride component is 100 mol%.

Specific examples of the above-mentioned soft diamine include oxydianiline (ODA), bis aminophenoxy benzene (133APB, 134APB), bis amino phenoxy phenyl hexafluoropropane (4BDAF), bis aminophenyl hexafluoro propane (33-6F , 44-6F), bis aminophenylsulfone (4DDS, 3DDS), bis amino phenoxy phenylpropane (6HMDA), bis aminohydroxy phenyl hexafluoropropane (DBOH), bis aminophenoxy diphenyl sulfone (DBSDA), etc. Although these are mentioned, It is not specifically limited. One type of such soft diamine may be used, or two or more types thereof may be used in appropriate combination. The content is also not particularly limited, but is preferably 0 to 70 mol% when the total diamine component is 100 mol%.

The polyimide film of this invention can also contain diamine and dianhydride other than the diamine and dianhydride which were demonstrated above. This content is also not particularly limited.

More specifically, the polyimide film of the present invention may include a repeating unit represented by the following Chemical Formulas 1 and 2.

Formula 1

Formula 2

In this case, the content of the repeating unit of Formula 1 and the content of the repeating unit of Formula 2 are preferably contained in a molar ratio of 30 ~ 70:30 ~ 70.

The polyimide film of the present invention can be produced by a known conventional method. When polymerizing the polyamic acid solution, which is a precursor of the polyimide, the polyamic acid solution can be prepared by dissolving and reacting the dianhydride component and the diamine component in an organic solvent in an almost equimolar amount.

Although the conditions at the time of reaction are not specifically limited, The reaction temperature is preferably -20 to 80 ° C, and the reaction time is preferably 2 to 48 hours. Moreover, it is more preferable that it is inert atmosphere, such as argon and nitrogen, at the time of reaction.

The organic solvent for the polymerization reaction of the polyamic acid solution is not particularly limited as long as it is a solvent in which the polyamic acid is dissolved. As a known reaction solvent, one selected from m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, and diethyl acetate The above polar solvent is used. In addition, low boiling point solutions such as tetrahydrofuran (THF), chloroform or low absorbing solvents such as γ-butyrolactone may be used.

Although not particularly limited with respect to the content of the organic solvent, in order to obtain the molecular weight and viscosity of the appropriate polyamic acid solution, the organic solvent is preferably 50 to 95% by weight of the total polyamic acid solution, more preferably 80 to 90% by weight It is more preferable.

In addition, when preparing a polyimide film using a polyamic acid solution, a filler may be added to the polyamic acid solution for the purpose of improving various properties such as the sliding property, thermal conductivity, conductivity, and corona resistance of the polyimide film. Although it does not specifically limit as a filler, As a preferable specific example, a silica, titanium oxide, layered silica, carbon nanotube, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, etc. are mentioned.

The particle diameter of the filler may vary depending on the characteristics of the film to be modified and the type of filler to be added, but is not particularly limited. In general, the average particle diameter is preferably 0.001 to 25 μm, and preferably 0.005 to 5 μm. More preferably, it is more preferable that it is 0.01-1 micrometer. In this case, the effect of modifying the polyimide film tends to appear, and good surface properties and mechanical properties can be obtained in the polyimide film.

Moreover, it does not specifically limit as it can fluctuate also with the film characteristic to be modified, filler particle diameter, etc. about the addition amount of the said filler. In general, the content of the filler is preferably 0.001 to 20 parts by weight, more preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the polyamic acid solution in order to exhibit the properties to be modified without disturbing the bonding structure of the polymer resin. It is good that it is a weight part.

On the other hand, it is preferable to surface-treat the surface of a filler using a titanium series or a siloxane coupling agent in order to improve dispersibility.

In addition, the filler is preferably an average particle diameter of 0.5㎛ or less, which is because the surface roughness due to the projections in the fine pattern is formed to act as a foreign material, so to control the filler particle size as described above to form a desirable pattern (fine pattern) good.

The addition method of a filler is not specifically limited, For example, the method of adding to a polyamic-acid solution before superposition | polymerization or after superposition | polymerization, the method of kneading a filler using 3 rolls etc. after completion | finish of polyamic acid polymerization, the dispersion liquid containing filler The method of preparing and mixing this into a polyamic-acid solution, etc. are mentioned.

As a method for preparing a polyimide film from the obtained polyamic acid solution, a conventionally known method may be used, that is, the polyamic acid solution may be cast on a support to imide to obtain a film.

As an imidation method applied at this time, it can apply in combination with the thermal imidation method, the chemical imidation method, or the thermal imidation method and the compound imidation method. The chemical imidization method is a method in which a dehydrating agent represented by acid anhydrides such as acetic anhydride and an imidization catalyst represented by tertiary amines such as isoquinoline, β-picoline and pyridine are introduced into a polyamic acid solution. In the case of using the thermal imidization method or the thermal imidization method together with the chemical imidization method, the heating conditions of the polyamic acid solution may vary depending on the kind of the polyamic acid solution, the thickness of the polyimide film to be produced, and the like.

When explaining the production example of the polyimide film in the case of using the thermal imidation method and the chemical imidation method more specifically, 80-200 degreeC, after casting a dehydrating agent and an imidation catalyst in a polyamic-acid solution, and casting on a support body, Preferably, after heating at 100-180 ° C. to activate the dehydrating agent and the imidization catalyst, the polyamic acid film in the gel state is obtained from the support after being partially cured and dried, and the film in the gel state is fixed to the support 200-500 A polyimide film can be obtained by heating at 5 degreeC for 5 to 400 second. The gel film can be fixed using a pin type frame or a clip type. As the support, a glass plate, an aluminum foil, a circulation stainless belt, a stainless drum, or the like can be used.

The polyimide film of this invention can be provided as COF for LCD and other semiconductor packaging materials.

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

<Example 1>

Fill 600 g of N, N-dimethylformamide (DMF) while passing nitrogen through a 1L reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, and then adjust the temperature of the reactor to 25 ° C and then pPDA 39.559 g (0.36 mol) was dissolved to maintain this solution at 25 ° C. 56.741 g (0.18 mol) of ODPA was added thereto and stirred for 30 minutes to completely dissolve and react ODPA. At this time, the temperature of the solution was maintained at 25 ℃. PMDA 39.90 g (0.18 mol) was added to obtain a polyamic acid of 3000 poises at a viscosity of 2000 poises.

The polyamic acid solution obtained above was stirred at 40 ° C. for 1 hour, degassed under vacuum, and then 100 parts by weight of polyamic acid, N, N-dimethylformamide (1 mol), acetic anhydride (2 mol) and pyridine (1 mol) After mixing 100 parts by weight of a mixed solvent with a mixer at 0 ° C., the obtained solution was cast on a stainless plate at 300 μm, dried with hot air at 150 ° C. for 10 minutes, and the film was peeled off from the stainless plate to fix it with a pin.

The film on which the film was fixed was placed in a hot oven, heated at 200 ° C. to 400 ° C. for 30 minutes, and slowly cooled to separate from the frame to obtain a polyimide film. (25 micrometers in thickness).

The linear expansion coefficient and the moisture absorption rate of the polyimide film obtained above were measured. The results are as shown in Table 1 below.

<Examples 2 to 7>

A polyamic acid solution was prepared in the same manner as in Example 1, except that the components and amounts of diamine and dianhydride were changed as shown in the following molar ratio of Table 1, and imidized to measure the coefficient of linear expansion and moisture absorption. It was. Evaluation results of the formed films are as shown in Table 1 below.

Comparative Example 1

After filling with 743 g of N, N-dimethylformamide (DMF) while passing nitrogen through a 1L reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller, and a cooler as a reactor, the temperature of the reactor was adjusted to 25 ° C, followed by ODA. 72.086 g (0.36 mol) was dissolved to maintain this solution at 25 ° C. 56.741 g (0.18 mol) of ODPA was added thereto and stirred for 30 minutes to completely dissolve and react ODPA. At this time, the temperature of the solution was maintained at 25 ℃. Then, 39.90 g (0.18 mol) of PMDA was added to obtain a polyamic acid of 3000 poise at a viscosity of 2000 poise, and a polyimide film was obtained in the same manner as in Example 1. (25 micrometers in thickness).

<Comparative Example 2-5>

A polyimide film (thickness 25 μm) was prepared in the same manner as in Comparative Example 1, except that the components and amounts of diamine and dianhydride were changed as in the molar ratio of Table 1 below, and the coefficient of linear expansion and moisture absorption rate Was measured. The results are as shown in Table 1 below.

The linear expansion coefficient and the moisture absorption rate of the polyimide films prepared in Examples and Comparative Examples were measured as follows, and the results are shown in Table 1 below.

(1) coefficient of linear expansion

After heat-treating the sample at 250 ° C. for one hour using TMA (TA, Q400), the average thermal expansion coefficient was measured at 50 ° C. to 200 ° C. at a heating rate of 10 ° C./min.

(2) moisture absorption rate

10 × 10㎠ polyimide film was dried in an oven at 150 ° C. for 24 hours, weighed, and completely immersed in pure water, left for 24 hours, then removed, wiped dry, and weighed to increase the weight. Calculate the ratio of weight to find the moisture absorption rate.

As a result of evaluating the physical properties, there was no problem in forming a film when including PMDA and ODPA in an appropriate ratio while including 30 mole% or more of pPDA as a diamine, and the polyimide film of the present invention had a very low coefficient of linear expansion and a moisture absorption rate of 1.4. It was found that the dimensional stability was very low at less than%.

On the other hand, satisfactory linear expansion coefficient and hygroscopicity were not exhibited when pPDA was not included or PMDA content was less than 30 mol%. In addition, when the content of PMDA exceeds 70 mol%, the rigidity of the film is increased and the film was not formed.

Therefore, the embodiments of the present invention maintain a very low level of linear expansion coefficient of 7.0ppm / ℃ or less at 50 ~ 200 ℃, when deformation on the glass substrate, silicon panel or LCD panel easily occurs deformation due to the difference in the coefficient of linear expansion It will be appreciated that it will not be, and therefore it is found to be desirable for forming fine patterns by applying to LCD COF and other semiconductor packaging materials.

Claims (6)

Aromatic dianhydrides containing pyromellitic acid dianhydride (PMDA) and aromatic diamines containing p-phenylenediamine (p-PDA) are used as the main raw materials, and TMA-Method based on film thickness of 5 to 100 μm. The polyimide film whose average linear expansion coefficient measured at 50-200 degreeC by 7.0 ppm / degrees C or less. The method of claim 1, Polyimide film characterized in that the moisture absorption is 1.4% or less. The method of claim 1, Containing an —, —O—, —CO—, —NHCO—, —S—, —SO ₂ —, —CO—O—, —CH ₂ —, —C (CH ₃ ) ₂ — chain between the aromatic rings Polyimide film, characterized in that it further comprises a flexible dianhydride or a soft diamine. The method of claim 1, To a polyimide film comprising a repeating unit of Formula 1 and Formula 2. Formula 1

Formula 2

The method of claim 1, When the total dianhydride component is 100 mol%, pyromellitic acid dianhydride (PMDA) is contained 30 mol% to 70 mol%, and when the total diamine component is 100 mol%, p-phenylenediamine ( p-PDA) is a polyimide film, characterized in that contained 30 mol% or more. The substrate for semiconductor packaging containing the polyimide film of any one of Claims 1-5.