KR101503332B1 - Polyimide film and preparation method thereof - Google Patents

Abstract

The present invention relates to a polyimide film and a method for preparing the same. The polyimide film of the present invention comprises a polyimide resin; and fluorinated particles composed of first particles having an average particle diameter of 300 nm or smaller and second particles having an average particle diameter of 10 μm or smaller and an average appearance specific gravity of 1.2 g/ml or less, wherein the second particle is formed by agglomeration of the first particles and thus has pores with an average diameter of 300 nm or smaller. The polyimide film of the present invention can have excellent physical properties and exhibit a low dielectric constant, and thus can be favorably used in the manufacture of electric/electronic devices and components such as a printed circuit board requiring a low-dielectric constant.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polyimide film,

The present invention relates to a low dielectric constant polyimide film having excellent physical properties and a method for producing the same.

Generally, polyimide (PI) resin refers to a high heat-resistant resin prepared by preparing a polyamic acid derivative by combining an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate in solution, and then dehydrating and dehydrating the polymer at a high temperature.

Polyimide resins are widely used in the fields of electric / electronic materials, space / aviation and telecommunication because of their excellent mechanical and thermal dimensional stability and chemical stability. Particularly, since polyimide resin has high insulation performance, it is widely applied to printed circuit boards and the like as parts and members requiring reliability.

BACKGROUND ART [0002] In recent years, in electronic equipment for accumulating a large amount of information in accordance with the tendency of high-level informatization and processing such information at a high speed and delivering it at a high speed, polyimide resins used therefor are required to have high performance, Anger is being demanded.

As an attempt to lower the dielectric constant of such a polyimide resin, for example, Korean Patent No. 0859275 discloses a method of dispersing a dispersible compound in a polyimide resin precursor solution, forming a coating film using the dispersion solution, extracting a dispersing compound To thereby produce a porous polyimide resin.

However, since the porous polyimide resin produced by the above method has pores of micro-unit size, there are limitations in realizing a thin polyimide film.

Korean Patent No. 0859275

Accordingly, an object of the present invention is to provide a low dielectric constant polyimide film having excellent physical properties and having nano-sized pores and a method for producing the same.

In order to achieve the above object,

Polyimide resin; And primary particles having an average particle diameter of 300 nm or less and fluorine-based particles composed of secondary particles having an average particle size of 10 탆 or less and an average apparent specific gravity of 1.2 g / ml or less, the primary particles having aggregated therein pores having an average diameter of 300 nm or less And a polyimide film.

The present invention also relates to

A primary particle having an average particle diameter of 300 nm or less and a primary particle having an average particle size of 10 mu m or less and an average apparent specific gravity of 1.2 g / ml or less having pores having an average diameter of 300 nm or less by agglomeration of the primary particles And then imidizing the fluorine-based particles composed of the second particles of the fluorine-based particles.

The polyimide film of the present invention uniformly contains the fluorine-containing particles having pores of a specific size in the film, thereby exhibiting the electrical characteristics of the fluorine single particles, and realizing a porous form due to the pores, And can be usefully used in the production of electric / electronic devices and parts such as a printed circuit board in which a low dielectric constant is required. In addition, by selectively using the fluorine-based particles capable of achieving the average apparent specific gravity through the pore, it is possible to prevent the particles from sinking due to application of fluorine particles having a high specific gravity, There is an advantage that it is not necessary to add a dispersant in order to uniformly distribute the particles and to improve dispersibility.

1 is a SEM photograph of a fluorine-based primary particle applied for the realization of the present invention.
2 is a SEM photograph of secondary particles formed by aggregation of fluorine-based primary particles applied for the realization of the present invention.
FIG. 3 is a cross-sectional SEM photograph of a polyimide film (prepared in Example 1) prepared by applying secondary particles formed by aggregation of fluorine-based primary particles for realizing the present invention.

The polyimide film of the present invention includes a polyimide resin; And primary particles having an average particle diameter of 300 nm or less and fluorine-based particles composed of secondary particles having an average particle size of 10 탆 or less and an average apparent specific gravity of 1.2 g / ml or less, the primary particles having aggregated therein pores having an average diameter of 300 nm or less The fluorine-based particles are preferably uniformly dispersed in the polyimide resin.

The polyimide film of the present invention comprises a polyimide precursor, an imidization conversion liquid, primary particles having an average particle diameter of 300 nm or less, primary particles having an average particle diameter of 10 mu m or less, By mixing fluorine-based particles composed of secondary particles having an average apparent specific gravity of 1.2 g / ml or less and performing an imidation process.

The method for producing the fluorine-based particles used in the present invention is not particularly limited as long as it can be produced by implementing the above-mentioned parameters.

Preferably, the primary particles constituting the fluorine-based particles may have an average particle diameter of 50 to 300 nm, the secondary particles may have an average particle diameter of 3 to 10 μm and pores having an average diameter of 50 to 300 nm, g / ml. < / RTI >

The fluorine-based particles added for realizing the dielectric constant property of polyimide are preferably fluorine-based resins having a melting point of 200 DEG C or higher, and specific examples thereof include polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP).

The polyimide film of the present invention may contain the fluorine-based particles in an amount of 5 to 40% by weight, preferably 10 to 30% by weight, based on the total weight of the film.

When the content of the fluorine-containing particles having the above-mentioned characteristics is within the above-mentioned range, it is possible to prevent the deterioration of the properties of the fluorine-based particles due to the high temperature in the production process of the polyimide film and to exhibit the dielectric constant property of the polyimide film to be realized, The mechanical strength of the polyimide film can be maintained.

The polyimide precursor used in the present invention may be any polyimide resin that can be made into a polyimide resin by imidization, preferably a polyamic acid obtained by copolymerizing an acid dianhydride component and a diamine component by a conventional method .

The acid dianhydride component and the diamine component may be appropriately selected from conventionally used ones.

Specific examples of the acid dianhydride component include biphenylcarboxylic acid dianhydride or derivatives thereof, pyromellitic dianhydride or derivatives thereof, and examples of the diamine component include phenylenediamine or a derivative thereof, diaminophenyl ether or A derivative thereof and the like can be used.

The imidization conversion liquid used in the present invention may be any material conventionally used for causing chemical hardening, and it may be a mixed solution of three kinds of dehydrating agents, catalysts and polar organic solvents. More specifically, the imidization conversion liquid may include a dehydrating agent such as acetic acid dianhydride; Tertiary amine catalysts such as pyridine, beta picoline and isoquinoline; And a polar organic solvent such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMAc).

The imidization conversion liquid may be used in an amount of 30 to 70 parts by weight based on 100 parts by weight of the polyimide precursor, but may vary depending on the kind of the polyimide precursor and the thickness of the polyimide film to be produced.

As a more specific example, the polyimide film of the present invention can be produced by a conventional method known in the art as follows.

First, an acid dianhydride component and a diamine component are copolymerized in an organic solvent to obtain a polyamic acid solution. In this case, the organic solvent is generally an aprotic solvent such as N, N'-dimethylformamide, N, N'-dimethylacetamide, N-methyl-pyrrolidone , Or a mixture thereof.

At this time, a filler may be added to the polyamic acid solution to improve various properties such as the sliding properties, thermal conductivity, conductivity, and corona resistance of the polyimide film. Examples of fillers that can be used include, but are not limited to, silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

To the polyamic acid solution obtained above, an imidization conversion liquid containing a dehydrating agent, a catalyst and a polar organic solvent was added and primary mixed. Primary particles having an average particle diameter of 300 nm or less and primary particles thereof aggregated to form an average Based particles composed of secondary particles having an average particle size of 10 mu m or less and an average apparent specific gravity of 1.2 g / ml or less having pores of 300 nm or less in diameter are added and mixed.

At this time, the imidization conversion liquid and the fluorine-based particles may be introduced at the same time without any time difference, or they may be charged into a dispersion liquid in which the fluorine-based particles are dispersed in the polar organic solvent.

 The mixed solution is coated on a support (for example, a glass plate, an aluminum foil, a circulating stainless belt, a stainless steel drum, etc.) and imidized to obtain a desired polyimide film.

The polyamic acid coating layer formed on the support is chemically partially imidized by a first heat treatment and then imidized completely by a second heat treatment to obtain a desired polyimide film. The first heat treatment for chemical partial imidization may be performed at 100 to 200 ° C for 5 to 15 minutes and the second heat treatment for complete imidization may be performed at 250 to 850 ° C for 5 to 15 minutes. In this case, the first heat-treated polyimic acid film with the chemical partially imidized state can be separated from the support and subjected to the second heat treatment. In the second heat treatment, the residual stress inside the film can be removed by heat treatment under a certain tension.

The thus-fabricated polyimide film according to the present invention has a low dielectric constant of 2.3 to 2.9 at 1 MHz.

Since the coefficient of thermal expansion of the film depends on the characteristics of the polyimide varnish, the polyimide film of the present invention containing the fluorine-based particles uniformly in the film is relatively low in comparison with the polyimide film produced by applying the fluorine-based monomer And the fluorine-based particles can not be directly projected on the surface of the film, thereby realizing a high adhesive force of the film. Therefore, it can be applied to an FPCB material such as a copper-clad laminate or a reinforced plate.

The polyimide film of the present invention uniformly contains the fluorine-containing particles having pores of a specific size in the film, thereby exhibiting the electrical characteristics of the fluorine single particles, and realizing a porous form due to the pores, And can be usefully used in the production of electric / electronic devices and parts such as a printed circuit board in which a low dielectric constant is required. In addition, by selectively using the fluorine-based particles capable of achieving the average apparent specific gravity through the pore, it is possible to prevent the particles from sinking due to application of fluorine particles having a high specific gravity, There is an advantage that it is not necessary to add a dispersant in order to uniformly distribute the particles and to improve dispersibility.

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

Production Example 1: Preparation of polyamic acid solution

320 g of dimethylformamide (DMF) was placed in a 0.5 L reactor and the temperature was set to 20 ° C. 27.59 g of diaminophenyl ether (ODA) was added to dissolve and then 20.03 g of pyromellitic dianhydride (PMDA) And then dissolved. After dissolution, 3.97 g of phenylenediamine (pPDA) was added thereto and reacted for 30 minutes, and then the solution was sampled to measure the molecular weight. After the reaction was completed, the temperature of the reactor was raised to 30 ° C, and 1.00 g of pPDA was added thereto to adjust the molar ratio of [diamine] / [dianhydride] to 1: 1. After the addition of the raw material was completed, the reaction was sufficiently carried out at 40 ° C for 2 hours to obtain a polyamic acid solution.

Production Example 2: Preparation of imidization conversion liquid to which fluorine particles are added (1)

4.5 g of isoquinoline (boiling point 242 占 폚) as an imide curing catalyst, 17.0 g of acetic anhydride as a dehydrating agent and 17.0 g of dimethylformamide (DMF) as a polar organic solvent were added 9.3 g of polytetrafluoroethylene (PTFE) 200 nm, 0.6 g / ml, and PTFE solid content: 30%) were mixed and stirred to prepare a fluorine-containing polymer fine particle having a mean particle diameter of 2 탆, porosity, average apparent specific gravity: 10 탆, To obtain 46.9 g of the imidized conversion solution.

Preparation Example 3: Preparation of imidization conversion liquid containing fluorine particles (2)

4.5 g of isoquinoline (boiling point: 242 DEG C) as an imide curing catalyst, 17.0 g of acetic anhydride as a dehydrating agent, and 14.9 g of DMF as a polar organic solvent were added 12.3 g of PTFE dispersion (available from Samil Chemical Co., 200 nm, 0.6 g / ml, solid content of PTFE: 30%) were mixed and stirred to obtain 48.7 g of an imidization conversion liquid to which fluorine particles were added.

Production Example 4: Preparation of imidization conversion liquid added with fluorine particles (3)

4.5 g of isoquinoline (boiling point 242 占 폚) as an imide curing catalyst, 17.0 g of acetic anhydride as a dehydrating agent, and 2.8 g of PTFE particles (manufactured by DAIKIN, average particle diameter 22 mu m, average apparent surface Specific gravity: 0.4 g / ml) were mixed and stirred to obtain 46.9 g of an imidization conversion liquid to which fluorine particles were added.

Preparation Example 5: Preparation of imidization conversion liquid containing fluorine particles (4)

4.5 g of isoquinoline (boiling point 242 DEG C) as an imide curing catalyst, 17.0 g of acetic anhydride as a dehydrating agent and 3.7 g of PTFE particles (manufactured by DAIKIN, average particle diameter 22 mu m, average apparent surface Specific gravity: 0.4 g / ml) were mixed and stirred to obtain 48.7 g of an imidization conversion liquid to which fluorine particles were added.

Production Example 6: Preparation of Imidization Conversion Liquid without Addition of Fluorine Particles (1)

4.5 g of isoquinoline (boiling point: 242 DEG C) as an imide curing catalyst, 17.0 g of acetic anhydride as a dehydrating agent, and 23.5 g of DMF as a polar organic solvent were mixed and stirred to obtain 45 g of an imidation conversion liquid.

Production Example 7: Preparation of imidization conversion liquid without addition of fluorine particles (2)

4.4 g of beta-picoline (boiling point 144 DEG C) as an imide curing catalyst, 16.7 g of acetic anhydride as a dehydrating agent, and 23.1 g of DMF as a polar organic solvent were mixed and stirred to obtain 45 g of an imidation conversion liquid.

Example 1: Production of fluorine-containing polyimide film

45 g of the imidization conversion solution obtained in Preparation Example 2 was mixed with 100 g of the polyamic acid polymer solution obtained in Preparation Example 1, and the resulting mixture was applied to a stainless steel plate. After drying for 3 minutes in a 120 ° C oven with hot air, the film was removed from the stainless plate, Respectively. After the film-fixed frame was heat-treated at 450 캜 for 7 minutes, the film was peeled off to obtain a polyimide film having an average thickness of 25 탆. A sectional SEM photograph of the polyimide film was shown in Fig.

Example  2: Manufacture of polyimide film with fluorine particles

A polyimide film having an average thickness of 25 占 퐉 was obtained by carrying out the same processes as in Example 1 except that 45g of the imidation conversion solution obtained in Production Example 3 was used instead of the imidization conversion solution obtained in Production Example 2.

Comparative Examples 1 and 2: Production of polyimide film using fluorine particles having different particle sizes and apparent density

A polyimide film having an average thickness of 25 占 퐉 was obtained by carrying out the same processes as in Example 1 except that 45g of the imidization conversion solution obtained in Production Example 4 or 5 was used instead of the imidization conversion solution obtained in Production Example 2.

Comparative Examples 3 and 4: Production of fluorine-free polyimide film

A polyimide film having an average thickness of 25 탆 was obtained by carrying out the same processes as in Example 1 except that 45 g of the imidization conversion solution obtained in Production Example 6 or 7 was used in place of the imidization conversion solution obtained in Production Example 2.

Corona treatment of film

The polyimide films produced in Examples 1 to 2 and Comparative Examples 1 to 4 were subjected to corona treatment with the above 4 kW output using a corona discharge treatment apparatus (model name: AGI: 060M, 063M, manufactured by Kasuga Denki K.K.) .

Test Example 1: Measurement of average particle diameter of primary particles and average diameter of pores

The average particle diameter and pore diameter of the primary particles of the fluorine-based particles used for the present invention were observed using a scanning electron microscope FE-SEM (model JSM-6700F available from JEOL) The images of 200 primary particles and pores were selected and the average was calculated by measuring the size. The measured values are shown in Table 1, and an SEM photograph of the fluorine primary particles is shown in FIG.

Test Example 2: Measurement of average particle diameter of secondary particles

The average particle size of the secondary particles of the fluorine-based particles used for the present invention was measured using a laser diffraction particle size analyzer (SHIMADZU, model SALD-2201). The measured values are shown in Table 1 below, and an SEM photograph of the secondary particles formed by aggregation of the fluorine primary particles is shown in Fig.

Test Example 3: Measurement of average apparent specific gravity of secondary particles

The average apparent specific gravity of the secondary particles of the fluorine-based particles used for the present invention was measured using a volume density meter and a density cup (YASUDA, Model 536, 558). The measured values are shown in Table 1 below.

Test Example 4: Measurement of dielectric constant and dielectric tangent

The 1 MHz dielectric constant and dielectric tangent of the polyimide films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were measured using DS-6000 manufactured by Lacerta. The measured dielectric constant and dielectric loss tangent are shown in Table 1 below.

Test Example 5: Measurement of thermal expansion coefficient (linear expansion coefficient)

The polyimide films prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were cut to a width of 5 mm and a length of 16 mm and a coefficient of thermal expansion (CTE) value was measured using a thermal mechanical apparatus Q400 Were measured. The sample was heated from 30 占 폚 to 420 占 폚 at a rate of 10 占 폚 / min and the coefficient of thermal expansion was determined within the range of 50 占 폚 to 200 占 폚. The measured values of the thermal expansion coefficient (linear expansion coefficient) are shown in Table 1 below.

Test Example 6: Measurement of Adhesion

Bonding sheets (1 mil, Epoxy type, Hanwha L & C products) were placed between the polyimide films prepared in Examples 1 and 2 and Comparative Examples 1 to 4 and copper foil (2/3 oz, manufactured by Iljin Materials) The film was heated to 180 ° C., thermocompressed at a pressure of 3 Mpa for 30 minutes, and then the pressure was released. Further, the film was cured in an oven at 200 ° C. for 30 minutes to obtain a flexible substrate. The resulting flexible substrate was cut to a width of 5 mm, and its adhesion was measured by a 90 ° wheel test of the IPC TM 659 2.4.9D method. The measured adhesion values are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Polyamic acid solution Production Example 1 Imidization conversion amount Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Production Example 7 Fluorine-based particle type PTFE PTFE PTFE PTFE - - Fluorine-based particles
Usage ratio (% by weight) 15 20 15 20 0 0 Average particle size of primary particles (nm) 200 200 - - - - Average diameter of pores (nm) 200 200 none none - - The average grain size (um) of the two- 10 10 22 22 - - Average apparent specific gravity of the two investors (g / ml) 0.6 0.6 0.4 0.4 - - Permittivity (1 kHz) 2.91 2.66 3.25 3.15 3.41 3.39 Dielectric tangent (1 kHz) 0.001 0.001 0.001 0.001 0.002 0.003 Film average thickness (um) 25 25 25 25 25 25 Adhesion (N / cm) 1.2 to 1.5 1.2 to 1.5 1.2 to 1.5 1.2 to 1.5 1.2 to 1.5 1.2 to 1.5 Linear expansion coefficient (ppm / ° C) 18.3 17.5 18.1 18.5 16.5 16.3

From the results shown in Table 1, it can be seen that the polyimide films of Examples 1 and 2 of the present invention exhibit a lower dielectric constant than the polyimide films of Comparative Examples 1 to 4 while exhibiting excellent physical properties. Therefore, the polyimide film of the present invention can be usefully used for the production of electric / electronic devices and parts such as a printed circuit board in which a low dielectric constant is required.

Claims (6)

Polyimide resin; And primary particles having an average particle diameter of 300 nm or less and fluorine-based particles composed of secondary particles having an average particle size of 10 탆 or less and an average apparent specific gravity of 1.2 g / ml or less, the primary particles having aggregated therein pores having an average diameter of 300 nm or less Containing polyimide film. The method according to claim 1,
Wherein the fluorine-based particles have a primary particle having an average particle diameter of 50 to 300 nm and a secondary particle having an average particle diameter of 3 to 10 占 퐉 and an average apparent specific gravity of 0.4 to 1.2 g / ml and having pores having an average diameter of 50 to 300 nm By weight based on the total weight of the film, and is contained in an amount of 5 to 40% by weight based on the total weight of the film. The method according to claim 1,
Wherein the fluorine-based particles are a fluorine-based resin having a melting point of 200 캜 or more. The method of claim 3,
Wherein the fluororesin is at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), and fluorinated ethylene propylene (FEP). The method according to claim 1,
Wherein the polyimide film has a low dielectric constant of 2.3 to 2.9 at 1 MHz. A primary particle having an average particle size of 300 nm or less and a primary particle having an average particle size of 10 mu m or less and an average apparent specific gravity of 1.2 g / ml or less having pores having an average diameter of 300 nm or less by agglomeration of the primary particles Wherein the fluorine-based particles composed of the secondary particles of the fluorine-containing particles are mixed and then imidized.

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