KR20140022629A - Polyimde film - Google Patents

Abstract

The present invention relates to a polyimide film and more specifically, to a polyimide film manufactured by imidization of polyamic acid formed with acid anhydride and diamine. The acid anhydride comprises 60-90 mol% of 3,3',4,4'- biphenyltetracarboxylic dianhydride which is an aromatic dicarboxylic acid; and 10-40 mol% of 4,4'- oxydiphthalic anhydride which is an aromatic anhydride. The diamine comprises 10-30 mol% of 3,5-diaminobenzotrifluoride or 2,4-toluilenediamine; and 70-90 mol% of 2,5-diaminotoluen or p-phenyldiamin.

Description

Polyimide Film {Polyimde Film}

The present invention relates to a polyimide film.

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.

In particular, the polyimide film has been widely used as a flexible printed circuit board material having a fine pattern, for example, a base film such as TAB or COF, due to light and small sized parts.

TAB or COF technology is a kind of technology for sealing IC chip or LSI chip. Specifically, TAB or COF technology is used to make a conductive pattern on a flexible tape and seal it by mounting the chip on it. It is advantageous to reduce the thickness of the product.

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

Then, the TAB tape is exposed to a high temperature (about 300 ° C.) through a solder reflow process in order to electrically connect the chip to the substrate. At this time, gas is generated as moisture absorbs and the water is released, which may form a foam between the conductive pattern and the polyimide film. To solve this problem, the moisture absorption rate should be small.

In addition, in consideration of economical aspects along with miniaturization and advancement of products, flexible circuit boards such as TAB and COF have tended to decrease significantly in pitch, and in order to cope with this trend, polyimide films have improved performance. It requires something to be done.

In addition, optical inspection is performed during product defect inspection, and it is difficult to detect defects due to distortion of light, and thus it is necessary to improve transmittance.

As such, research and development have been conducted to improve characteristics such as dimensional stability, moisture absorption rate, line width, etc. of the polyimide film required in the field in which the polyimide film is used. It is necessary to improve various physical properties of polyimide films such as light transmittance and high heat resistance.

The present invention is to provide a polyimide film having a high glass transition temperature and a high modulus of elasticity, excellent dimensional stability, and high mountability.

Accordingly, the present invention is a first preferred embodiment, in the polyimide film prepared by imidizing a polyamic acid consisting of acid anhydride and diamine, the acid anhydride is an aromatic dicarboxylic acid 3,3'4,4'-biphenyl 60 to 90 mole percent of tetracarboxylic dianhydride and 10 to 40 mole percent of 4,4'-oxydiphthalic anhydride, which is an aromatic anhydride, wherein the diamine is 3,5-diaminobenzotrifluoride or 10-30 mol% of 2, 4- toluylene diamine; And it provides a polyimide film, characterized in that it comprises 70 to 90 mol% of 2,5-diaminotoluene or p-phenylenediamine.

Polyimide film according to the embodiment may have a thermal expansion coefficient of 3 ~ 20ppm / ℃.

The light transmittance may be 88% or more at a wavelength of 550nm according to the embodiment.

The polyimide film according to the present invention exhibits excellent dimensional stability, high light transmittance, and excellent mountability.

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

The present invention is a polyimide film prepared by imidizing a polyamic acid consisting of acid anhydride and diamine, wherein the acid anhydride is an aromatic dicarboxylic acid 3,3'4,4'-biphenyl tetracarboxylic acid dianhydride 60 ~ 90 Mole% and 10-40 mole% of 4,4′-oxydiphthalic anhydride, which is an aromatic anhydride, wherein the diamine is 3,5-diaminobenzotrifluoride or 2,4-toluylenediamine 10-30 mol%; And it provides a polyimide film, characterized in that it comprises 70 to 90 mol% of 2,5-diaminotoluene or p-phenylenediamine. In this case, the acid anhydride and the diamine may be equimolar.

The polyimide film according to the present invention may have a thermal expansion coefficient of 3 to 20 ppm / ° C. and a light transmittance of 88% or more at a wavelength of 550 nm.

In the present invention, the acid anhydride includes aromatic dicarboxylic acid and aromatic anhydride.

Specifically, the aromatic dicarboxylic acid may be 3,3'4,4'-biphenyl tetracarboxylic acid dianhydride, the content may be 60 to 90 mol% of the total acid anhydride. If the content of the 3,3'4,4'-biphenyl tetracarboxylic dianhydride is less than 60 mol%, there is a problem in that the moisture absorption rate of the film is increased. It is difficult to control, an unreacted monomer is generated, and the transmittance is low.

The aromatic anhydride may be 4,4'-oxydiphthalic anhydride, the content may be 10 to 40 mol% of the total acid anhydride. If the content of the 4,4'- oxydiphthalic anhydride is less than 10 mol%, there is a problem that the viscosity control becomes difficult and the transmittance is low due to solubility problems in the polymerization process, if the content exceeds 40 mol%, the glass transition temperature is lowered to a high temperature There is a problem of poor dimensional stability.

In the present invention, the diamine may be an aromatic diamine, specifically, the diamine is an aromatic diamine, 10 to 30 moles of 3,5-diaminobenzotrifluoride or 2,4-toluylenediamine for controlling transmittance. % And 70 to 90 mol% of 2,5-diaminotoluene p-phenylenediamine for controlling dimensional stability may be included.

If the content of 3,5-diaminobenzotrifluoride or 2,4-toluylenediamine is less than 10 mol%, the transmittance is low, and if it is more than 30 mol%, high temperature dimensional stability is inferior.

In addition, when the content of 2,5-diaminotoluene or p-phenylenediamine is less than 70 mol%, there is a problem that the high temperature dimensional stability is poor, and if it is more than 90 mol%, the transmittance is lowered.

In general, the film forming method of the polyimide film is not particularly noticeable to those skilled in the art, but one example is given. Get At this time, the solvent is preferably an aprotic polar solvent (Aprotic solvent) is generally used as the amide solvent, for example, N, N'- dimethylformamide, N, N'- dimethylacetamide, N-methyl -Pyrrolidone, and the like, and may be used in combination.

The acid anhydride and diamine may be added in the form of powder, lump, and solution.In the initial stage of the reaction, the acid anhydride and the diamine may be added in the form of powder. Do.

The weight of the acid anhydride and diamine in the total polyamic acid solution in a state in which the equimolar amount of acid anhydride and diamine is added is called a solid content. The polymerization proceeds in a range of 10 to 30% or 12 to 23% solid content. It is preferable.

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 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 gel filmed on the support by dry air and heat treatment. The manufacturing temperature conditions of the gel film is preferably 100 ℃ or more, and the support may be a glass plate, aluminum foil, a circulating stainless belt or a stainless drum, but is not limited thereto.

The treatment time required for gel film formation depends 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 certain time, but is preferably performed within a range of 5 to 30 minutes. Good to do.

The gel film is separated from the support and heat treated to complete drying and imidization. The heat treatment temperature is between 100 ~ 600 ℃ and the treatment time is between 1 ~ 30 minutes. At this time, the crystallinity of the crystallized film varies depending on the highest temperature, the maximum temperature is preferably 500 ℃ or more. The gel film can be fixed using a frame of a pin type or using a clip type.

The residual volatile content of the film after heat treatment is 3% or less, and preferably 1% or less.

After heat treatment, the film is heat treated under a constant tension to remove residual stress inside the film. Since the tension and temperature conditions are correlated with each other, the tension conditions may vary with temperature. Temperature is preferably maintained between 100 ~ 400 ℃, the tension is preferably 50N or less, the time is preferably maintained for 1 minute to 1 hour.

Hereinafter, the present invention will be described in detail with reference to the following Examples, the present invention is not limited by the Examples.

Example 1

838.87 g of N, N'-dimethylformamide (DMF) was added to a 2L jacket reactor as a solvent. The temperature was 25 ° C, 42.66 g of p-phenylenediamine (p-PDA) was added to dissolve, and then 109.23 g of 3,3 ', 4,4'-biphenyltecarboxylic dianhydride (BPDA) was added thereto. After stirring for about 30 minutes to confirm that the reaction was completed by changing the temperature inside the reactor, 12.26 g of 3,5-diaminobenzotrifluoride (DBTF) was added to dissolve it, and then 4,4'-oxydiphthalic anhydride (ODPA) was dissolved. ) 27.93 g was added thereto, and after the reaction was completed, the temperature was increased to 35 ° C., and 12.1 g of 4,4′-oxydiphthalic anhydride (ODPA) 7.2% solution was added in portions. After the addition, the mixture was stirred for 2 hours while maintaining the temperature at 40 ° C.

The completed polyamic acid solution had a solid content of 15 wt% and a viscosity of 1,800 poise. The molar ratio of the added monomer is an equimolar amount of acid anhydride and diamine. The acid anhydride is BPDA 80%, ODPA 20%, and diamine is DBTF 15% and PPD 85%.

100 g of this polyamic acid solution and 30 g of a conversion pharmaceutical solution (5.9 g of isoquinoline, 14 g of acetic anhydride, 10.1 g of anhydrous acetic acid) were uniformly stirred, applied to a stainless plate, cast at 100 μm, and dried for 5 minutes with 120 ° C. hot air. The gelled film (gel film) was peeled off the stainless plate and pinned to the frame.

The frame, to which the gel film was fixed, was placed in a curing furnace and slowly heated for 30 minutes in steps from 250 ° C. to 550 ° C. until the maximum temperature was 550 ° C. and then slowly cooled to separate the film from the frame. The thickness of the film finally obtained is 25 micrometers.

Examples 2 to 5

A polyimide film was prepared in the same manner as in Example 1, except that the composition of the acid anhydride monomer and the diamine monomer was changed as described in Table 1 during polyamic acid polymerization.

Comparative Examples 1 to 5

A polyimide film was prepared in the same manner as in Example 1, except that the composition of the acid anhydride monomer and the diamine monomer was changed as described in Table 1 during the polyamic acid polymerization.

A part of the polyimide films prepared in Examples and Comparative Examples were cut out, and the coefficient of thermal expansion, light transmittance, and DMA were measured as follows, and the results are shown in Table 2.

(1) Coefficient of thermal expansion

A portion of the polyimide film sample was cut to a size of 4 mm wide by 20 mm wide, and the coefficient of thermal expansion was measured using a thermal mechamical apparatus. Samples were measured by applying a force of 0.05 N on a quartz hook and heating at 10 ° C./min from 30 ° C. to 350 ° C. in a nitrogen atmosphere. The coefficient of thermal expansion was determined within the range of 50 ° C to 200 ° C.

(2) light transmittance

Light transmittance at wavelength 550 nm was measured using UV-VIS Spectroscopy (model name: cary5000).

(3) DMA evaluation (Tg measurement)

A part of the polyimide film sample was cut into a size of 4 mm in width x 30 mm in width, and Tg (Tan δ) was measured under TA DMA Q800 under the following conditions.

Measurement mode: Film Tension mode

Temperature raising condition: 5 ℃ / min

Measuring section: 30 ℃ ~ 450 ℃

Acid anhydride Diamine Unit (mol%) 3,3'4,4'-biphenyl tetracarboxylic dianhydride (BPDA) 4,4'-oxydiphthalic anhydride (ODPA) 3,5-diaminobenzotrifluoride (DBTF) 2,4-toluiylenediamine (MTD) 2,5-diaminotoluene (DAT) p-phenylenediamine (PPD) Example 1 80 20 15 - - 85 Example 2 70 30 - 15 - 85 Example 3 80 20 10 90 Example 4 70 30 10 90 Example 5 70 30 10 90 Comparative Example 1 PMDA 100 - ODA 20 80 Comparative Example 2 100 ODA 100 - Comparative Example 3 40 60 15 85 Comparative Example 4 100 15 85 Comparative Example 5 70 30 40 60

Coefficient of thermal expansion
(ppm) Light transmittance
(%) DMA (Tan δ)
(℃) Example 1 7 89 324 Example 2 9 91 310 Example 3 4 89 334 Example 4 9 88 330 Example 5 5 88 331 Comparative Example 1 16 64 410 Comparative Example 2 34 67 400 Comparative Example 3 12 92 280 Comparative Example 4 6 65 327 Comparative Example 5 22 92 290

Claims (3)

In the polyimide film produced by imidizing the polyamic acid of the acid anhydride and diamine,
The acid anhydride is 60 to 90 mol% of 3,3 ', 4,4'-biphenyl tetracarboxylic acid dianhydride which is aromatic dicarboxylic acid and 4 to 4'-oxydiphthalic anhydride which is aromatic anhydride. Contains mole%,
The diamine is 10 to 30 mol% of 3,5-diaminobenzotrifluoride or 2,4-toluylenediamine; And 70 to 90 mole% of 2,5-diaminotoluene or p-phenylenediamine.
The method of claim 1,
Polyimide film characterized in that the thermal expansion coefficient of 3 ~ 20ppm.
The method of claim 1,
Polyimide film, characterized in that the light transmittance is 88% or more at a wavelength of 550nm.