TWI765392B - Polyimide film, method of producing the same, and multilayer film, flexible metal foil laminate and electronic component containing the same - Google Patents

Abstract

The present invention provides a polyimide film with improved dielectric properties, wherein the polyimide film includes a block copolymer, the block copolymer includes: a first block, and the first block contains benzophenone The dianhydride components of tetracarboxylic dianhydride (BTDA) and biphenyltetracarboxylic dianhydride (BPDA) are obtained by imidization with a diamine component containing p-phenylenediamine (PPD); and the second block, the aforementioned No. The diblock is obtained by imidizing a dianhydride component containing biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) and a diamine component containing m-tolidine .

Description

Polyimide film, method for making the same, and multilayer film, flexible metal foil laminate, and electronic component comprising the same

The present invention relates to a polyimide film with improved dielectric properties and a manufacturing method thereof.

Polyimide (PI) is based on a rigid aromatic main chain and an imine ring with excellent chemical stability, and it has the highest level of heat resistance, chemical resistance, electrical insulation, and chemical resistance among organic materials. , Weather-resistant polymer materials.

In particular, due to its excellent insulating properties, that is, excellent electrical properties such as low dielectric constant, it has attracted much attention as a highly functional polymer material in the electrical, electronic and even optical fields.

Recently, with the reduction in weight and size of electronic products, highly integrated and flexible thin circuit boards have been actively developed.

Such thin circuit substrates tend to utilize a structure in which circuits including metal foils are formed on a polyimide film that is excellent in heat resistance, low temperature resistance, and insulating properties and is easily bendable.

As such a thin circuit board, a flexible metal foil laminate is mainly used, and as an example, a flexible copper clad laminate (FCCL) using a thin copper plate as a metal foil is included. Moreover, polyimide can also be used as a protective film, an insulating film, etc. of a thin circuit board.

On the other hand, recently, as various functions are built into electronic devices, the aforementioned electronic devices are required to have fast operation speed and communication speed. A thin circuit board for high-speed communication.

In order to realize high-frequency high-speed communication, an insulator with high impedance that can maintain electrical insulation even at high frequencies is required. Impedance is inversely proportional to the frequency and dielectric constant (Dk) formed in the insulator, so even at high frequencies, in order to maintain insulation, the dielectric constant should be as low as possible.

However, in the case of general polyimide, the dielectric properties are not excellent enough to maintain sufficient insulating properties in high-frequency communication.

In addition, it is reported that the lower the dielectric properties of the insulator, the more the occurrence of undesired stray capacitance and noise can be reduced in thin circuit substrates, which can largely eliminate the cause of communication delay.

Therefore, polyimide with low dielectric properties is considered to be the most important factor in the performance of thin circuit substrates.

Especially in terms of high-frequency communication, dielectric loss (dielectric dissipation) caused by polyimide will inevitably occur, and the dielectric loss factor (Dielectric Dissipation Factor; Df) means the degree of power waste of thin circuit substrates, and determines the communication speed. It is closely related to the signal transfer delay of , so keeping the dielectric loss factor of polyimide as low as possible is also considered to be an important factor in the performance of thin circuit substrates.

In addition, the more moisture contained in the polyimide film, the greater the dielectric constant and the greater the increase in the dielectric loss factor. Polyimide films are suitable for thin circuit substrates due to their excellent intrinsic properties, but on the contrary, they are relatively vulnerable to moisture due to their polar imide groups, resulting in poor insulation properties.

Therefore, there is an urgent need to develop a polyimide film having dielectric properties, especially a low dielectric loss factor, while maintaining the mechanical, thermal, and chemical resistance properties specific to polyimide at a given level.

[Prior Art Literature]

[Patent Literature]

Patent Document 1: Korean Laid-Open Patent Publication No. 10-2015-0069318.

Therefore, in order to solve the above-mentioned problems, it is an object to provide a polyimide film having high heat resistance, low dielectric properties, and low moisture absorption properties, and a method for producing the same.

Accordingly, the essential purpose of the present invention is to provide specific embodiments thereof.

An embodiment of the present invention aiming to achieve the above-mentioned purpose provides a polyimide film, the polyimide film includes a block copolymer, and the block copolymer includes: a first block, the first block Diphenyltetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride; BTDA) and biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride; BPDA) An anhydride component and a diamine component containing p-Phenylenediamine (PPD) are obtained by imidization; and a second block, wherein the second block contains biphenyltetracarboxylic dianhydride (BPDA) and It is obtained by imidizing a dianhydride component of pyromellitic dianhydride (PMDA) with a diamine component containing m-tolidine.

Based on the total content of the diamine components of the first block and the second block, 100 mol %, the content of m-tolidine can be more than 20 mol % and less than 35 mol %. The content can be more than 65 mol % and less than 80 mol %.

In addition, the content of benzophenone tetracarboxylic dianhydride is 10 mol % or more and 20 mol % or less based on 100 mol % of the total content of the dianhydride components in the first block and the second block, The content of biphenyltetracarboxylic dianhydride may be more than 40 mol % and less than 60 mol %, and the content of pyromellitic dianhydride may be more than 20 mol % and less than 45 mol %.

The dielectric loss factor (Df) of the polyimide film can be 0.004 or less, the thermal expansion coefficient (CTE) can be 16 ppm/°C or less, and the glass transition temperature (Tg) can be 300°C or more.

Another embodiment of the present invention provides a method for producing a polyimide film, comprising: (a) a step of polymerizing a first dianhydride component and a first diamine component in an organic solvent to produce a first polyimide film (b) the step of polymerizing the second dianhydride component and the second diamine component in an organic solvent to produce the second polyamic acid; (c) the aforementioned first polyamic acid and the second polyamic acid The step of producing the third polyamic acid by copolymerization in an organic solvent; and (d) the step of imidizing the precursor composition comprising the third polyamic acid on a support after forming a film; the above-mentioned step A dianhydride component includes benzophenone tetracarboxylic dianhydride (BTDA) and biphenyltetracarboxylic dianhydride (BPDA), and the second dianhydride component includes biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride, The said 1st diamine component contains p-phenylenediamine (PPD), and the said 2nd diamine component contains m-tolidine (m-tolidine).

To sum up, the present invention provides a polyimide film with high heat resistance, low dielectric properties and low moisture absorption properties by using a polyimide film composed of specific components and specific ratios and a manufacturing method thereof , so that it can be usefully applied to various fields requiring these properties, especially electronic components such as flexible metal foil laminates.

Hereinafter according to the present invention "polyimide film" and "polyimide film manufacturing method" In the order of "method", the embodiment of the invention will be described in more detail.

Prior to this, the terms or words used in this specification and the scope of the patent application should not be interpreted in the usual or dictionary senses, but should be interpreted on the basis that "the inventor can appropriately define his own invention in order to explain his own invention in the best way." The principle of "concept of term" is only interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the structure of the embodiment described in this specification is only the best embodiment of the present invention, and does not represent the technical idea of the present invention. Therefore, it should be understood that at the time of application of the present invention, there may be alternatives to replace them. Various equivalents and variants of .

In this specification, the expression of the singular includes the expression of the plural unless the difference is not clearly expressed in the text. In this specification, terms such as "comprising", "having" or "having" are to specify the existence of features, numbers, steps, constituent elements or their combinations, and should be understood as not pre-exclude one or more other The presence or additional possibility of features or numbers, steps, constituent elements or combinations thereof.

In this specification, when an amount, concentration, or other value or parameter is given by listing a range, a preferred range, or a preferred upper limit value and a preferred lower limit value, it should be understood that whether the range is disclosed independently or not All ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value are specifically disclosed.

When a range of values is referred to in this specification, unless recited differently, the range is meant to include its endpoint and all integers and fractions within the range. The scope of the invention is not meant to be limited to the specific values mentioned in defining the scope.

In this specification, "dianhydride" is meant to include its precursors or derivatives, which technically may not be dianhydrides, but nonetheless react with diamines to form polyamides, which may Converted to polyimide again.

In this specification, "diamine" is meant to include precursors or derivatives thereof, which may not technically be diamines, but nonetheless react with dianhydrides to form polyamides, which may again Converted to polyimide.

The polyimide film of the present invention includes a block copolymer, the block copolymer includes: a first block, and the first block contains benzophenone tetracarboxylic dianhydride (BTDA) and biphenyl tetracarboxylic dianhydride (BPDA) obtained by imidizing a dianhydride component and a diamine component containing p-phenylenediamine (PPD); and a second block containing biphenyltetracarboxylic dianhydride (BPDA) and a dianhydride component of pyromellitic dianhydride (PMDA) and a diamine component containing m-tolidine are obtained by imidization.

Based on the total content of the diamine components of the first block and the second block, 100 mol %, the content of m-tolidine can be more than 20 mol % and less than 35 mol %. The content can be more than 65 mol% and less than 80 mol%, especially the content of m-tolidine is preferably more than 20 mol% and less than 30 mol%. In particular, m-tolidine has a hydrophobic methyl group, which contributes to the low moisture absorption property of the polyimide film.

In addition, the content of benzophenone tetracarboxylic dianhydride may be 10 mol % or more and 20 mol % or less based on 100 mol % of the total content of the dianhydride components in the first block and the second block. The content of biphenyltetracarboxylic dianhydride may be more than 40 mol% and less than 60 mol%, and the content of pyromellitic dianhydride is more than 20 mol% and less than 45 mol%.

In particular, the content of the aforementioned benzophenone tetracarboxylic dianhydride is preferably 15 mol % or more and 20 mol % or less.

In the present invention, the polyimide chain derived from biphenyltetracarboxylic dianhydride has a structure named as a charge transfer complex (Charge Transfer Complex; CTC), that is, an electron donor (electron donnor) and an electron acceptor ( The regular linear structures of electron acceptors arranged close to each other enhance the intermolecular interaction.

In addition, benzophenone tetracarboxylic dianhydride having a carbonyl group is also the same as biphenyl tetracarboxylic dianhydride, Contributes to the expression of CTCs.

This structure has the effect of preventing hydrogen bonding with moisture, thereby having an effect on reducing the moisture absorption rate, and maximizing the effect of reducing the moisture absorption of the polyimide film.

In one specific example, the aforementioned dianhydride component may additionally contain pyromellitic dianhydride. Pyromellitic dianhydride is a dianhydride component having a relatively rigid structure, and is recommended because it can impart suitable elasticity to a polyimide film.

In order to satisfy suitable elasticity and moisture absorption at the same time in the polyimide film, the content ratio of dianhydride is particularly important. For example, as the content ratio of biphenyltetracarboxylic dianhydride decreases, it becomes difficult to expect a low moisture absorption rate due to the CTC structure.

In addition, biphenyltetracarboxylic dianhydride and benzophenonetetracarboxylic dianhydride contain two benzene rings corresponding to the aromatic moiety, whereas pyromellitic dianhydride contains one benzene ring corresponding to the aromatic moiety.

In the dianhydride component, the increase in the content of pyromellitic dianhydride, based on the same molecular weight, can be understood as an increase in the imide group in the molecule, which can be understood as the increase in the polyimide polymer chain, The ratio of the imide group derived from the above-mentioned pyromellitic dianhydride is relatively increased as compared with the imide group derived from biphenyltetracarboxylic dianhydride and benzophenone tetracarboxylic dianhydride.

That is, an increase in the content of pyromellitic dianhydride can be regarded as a relative increase in imide groups even with respect to the entire polyimide film, so it is difficult to expect a low moisture absorption rate.

On the contrary, when the content ratio of pyromellitic dianhydride is decreased, the components of the rigid structure are relatively decreased, and the elasticity of the polyimide film is decreased to a desired level or less.

For this reason, when the content of the aforementioned biphenyltetracarboxylic dianhydride and benzophenone tetracarboxylic dianhydride is higher than the aforementioned range or the content of the pyromellitic dianhydride is lower than the aforementioned range, the mechanical properties of the polyimide film It is low, and the heat resistance of the level suitable for manufacture of a flexible metal foil laminate cannot be ensured.

On the contrary, when the content of the aforementioned biphenyltetracarboxylic dianhydride and benzophenone tetracarboxylic dianhydride is lower than the aforementioned range or the content of pyromellitic dianhydride exceeds the aforementioned range, it is difficult to achieve a suitable level of dielectric constant and dielectric loss factor and moisture absorption rate, so it is not recommended.

The dielectric loss factor (Df) of the polyimide film can be 0.004 or less, the thermal expansion coefficient (CTE) can be 16 ppm/°C or less, and the glass transition temperature (Tg) can be 320°C or more.

In connection with this, when it is a polyimide film that satisfies all of the dielectric loss factor (Df), glass transition temperature, and thermal expansion coefficient, it can be used not only as an insulating film for flexible metal foil laminates, but also can be produced. Even if the flexible metal foil laminate is used as an electrical signal transmission circuit that transmits signals at high frequencies above 10GHz, its insulation stability can be ensured, and the signal transmission delay can be minimized.

All of the polyimide films having the aforementioned conditions are novel polyimide films that are hitherto unknown, and the dielectric dissipation factor (Df) is described in detail below.

[Dielectric Dissipation Factor]

"Dielectric loss factor" refers to the force that is destroyed by a dielectric (or insulator) when the friction of the molecules interferes with molecular motion due to alternating electric fields.

The value of the dielectric loss factor is generally used as an indicator of the ease of charge loss (dielectric loss). The higher the dielectric loss factor, the easier it is to lose the charge. Conversely, the lower the dielectric loss factor, the harder it is to lose the charge. That is, the dielectric loss factor is a measure of power loss, and the lower the dielectric loss factor, the more alleviated the signal transmission delay caused by the power loss, and the faster the communication speed can be maintained.

This is a matter strongly demanded of the polyimide film as an insulating film, and the polyimide film of the present invention can have a dielectric loss factor of 0.004 or less at an extremely high frequency of 10 GHz.

In the present invention, for example, the production of polyamic acid can be carried out by the following methods: (1) method, in which the whole amount of the diamine component is added to the solvent, and then the dianhydride component is added so as to be substantially equimolar with the diamine component. Polymerization; (2) method, adding the full amount of the dianhydride component to the solvent, then adding the diamine component to make it substantially equimolar with the dianhydride component and performing polymerization; (3) method, adding a part of the components in the diamine component to the solvent After the neutralization, a part of the dianhydride components are mixed at a ratio of about 95 to 105 mol% with respect to the reaction components, the remainder of the diamine component is added, and then the remainder of the dianhydride component is added to make the diamine component and the dianhydride component substantially up to equimolar and poly- (4) method, after adding the dianhydride component to the solvent, with respect to the reaction component, after mixing a part of the components in the diamine compound at a ratio of 95-105 mol%, adding other dianhydride components, and then adding the remaining diamine component, the diamine component and the dianhydride component are substantially equimolar and polymerized; (5) method, in which a part of the diamine component and a part of the dianhydride component are reacted in a solvent to make one of them excessive to form a first combination In another solvent, a part of the diamine component and a part of the dianhydride component are reacted to make one of them excessive, and after the second composition is formed, the first composition and the second composition are mixed to complete the polymerization, and at this time, In this method, when the first composition is formed, if the diamine component is excessive, the dianhydride component is excessive in the second composition, and when the dianhydride component is excessive in the first composition, in the second composition, The diamine component is made to be excessive, and the first and second compositions are mixed so that the entire diamine component and the dianhydride component used for their reaction are substantially equimolar and polymerized.

However, the above-mentioned polymerization method is not limited to the above-mentioned example, and it is needless to say that any known methods can be used for the production of the above-mentioned first to third polyamic acid.

In a specific example, the method for producing a polyimide film of the present invention may include: (a) a step of polymerizing the first dianhydride component and the first diamine component in an organic solvent to produce the first polyamide acid (b) the step of polymerizing the second dianhydride component and the second diamine component in an organic solvent to produce the second polyamic acid; (c) the aforementioned first polyamic acid and the second polyamic acid The step of producing the third polyamic acid by copolymerization in an organic solvent; and (d) the step of imidizing the precursor composition comprising the third polyamic acid on a support after forming a film; the above-mentioned step A dianhydride component includes benzophenone tetracarboxylic dianhydride (BTDA) and biphenyltetracarboxylic dianhydride (BPDA), and the second dianhydride component includes biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride, The said 1st diamine component contains p-phenylenediamine (PPD), and the said 2nd diamine component contains m-tolidine (m-tolidine).

Based on the total content of the aforementioned first diamine component and the aforementioned second diamine component of 100 mol %, the content of m-tolidine can be more than 20 mol % and less than 35 mol %, and the content of p-phenylenediamine It can be 65 mol% or more and 80 mol% or less.

In addition, the content of benzophenone tetracarboxylic dianhydride may be 10 mol % or more and 20 mol % or less based on 100 mol % of the total content of the aforementioned first dianhydride and the aforementioned second dianhydride components, biphenyl The content of tetracarboxylic dianhydride may be more than 40 mol % and less than 60 mol %, and the content of pyromellitic dianhydride may be more than 20 mol % and less than 45 mol %.

In the present invention, the polymerization method of the polyamic acid as described above can be defined as a random polymerization method, and the polyimide produced from the polyamic acid of the present invention produced by the above-mentioned process A thin film that maximizes the effect of the present invention in reducing the dielectric loss factor (Df) and moisture absorption rate can be preferably applied in this respect.

However, the above-mentioned polymerization method has limitations in that the length of the repeating unit in the polymer chain described above is relatively short, and therefore has limitations in exhibiting various excellent properties of the polyimide chain derived from the dianhydride component. Therefore, the method for polymerizing polyamic acid that can be particularly preferably used in the present invention may be a block polymerization method.

On the other hand, the solvent used for synthesizing the polyamic acid is not particularly limited, and any solvent may be used as long as it dissolves the polyamic acid, but an amide-based solvent is preferred.

Specifically, the aforementioned solvent may be an organic polar solvent, in detail, may be an aprotic polar solvent, for example, may be selected from N,N-dimethylformamide (DMF), N, One or more of the group consisting of N-dimethylacetamide, N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), and Diglyme, but not limited to these , can be used alone or in combination of two or more according to need.

In one example, the aforementioned solvent can be particularly preferably used N,N-dimethylformamide and N,N-Dimethylacetamide.

In addition, in the manufacturing process of polyamide, fillers can also be added for the purpose of improving various properties of the film such as sliding properties, thermal conductivity, corona resistance, and ring hardness. The filler material to be added is not particularly limited, as preferred examples, such as silicon dioxide, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.

The particle size of the filler is not particularly limited, and may be determined according to the properties of the film to be modified and the type of filler to be added. In general, the average particle size is 0.05 to 100 μm, preferably 0.1 to 75 μm, more preferably 0.1 to 50 μm, particularly preferably 0.1 to 25 μm.

If the particle size is less than this range, it is difficult to express the modification effect, and if it exceeds this range, the surface properties may be greatly damaged or the mechanical properties may be greatly reduced.

In addition, the addition amount of the filler is also not particularly limited, and may be determined according to the properties of the film to be modified, the particle size of the filler, and the like. Generally speaking, the addition amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, more preferably 0.02 to 80 parts by weight, relative to 100 parts by weight of polyimide.

If the amount of filler added is less than this range, it is difficult to exhibit the modification effect of the filler, and if it exceeds this range, the mechanical properties of the film may be greatly damaged. The method of adding the filler is not particularly limited, and any known method may be used.

In the production method of the present invention, the polyimide film can be produced by a thermal imidization method and a chemical imidization method.

In addition, it can also be produced by a composite imidization method in which a thermal imidization method and a chemical imidization method are used in combination.

The aforementioned thermal imidization method is a method of inducing an imidization reaction using a heat source such as hot air or an infrared dryer without using a chemical catalyst.

The aforementioned thermal imidization method can thermally treat the aforementioned gel film at a variable temperature ranging from 100 to 600° C. to achieve imidization of the amide groups present in the gel film. Heat treatment may be performed at 200 to 500° C., in more detail, at 300 to 500° C., to imidize the amide groups present in the gel film.

However, during the formation of the gel film, a portion (about 0.1 mol % to 10 mol %) of the amide acid is imidized by the amide, for which a variable temperature ranging from 50°C to 200°C can be The polyamic acid composition is dried under low temperature, which can also be included in the scope of the aforementioned thermal imidization method.

In the chemical imidization method, a polyimide film can be produced using a dehydrating agent and an imidizing agent according to a method known in the art.

As an example of the compound imidization method, after adding a dehydrating agent and an imidizing agent to the polyamic acid solution, it can be heated at 80 to 200°C, preferably 100 to 180°C, and partially cured. And after drying, the polyimide film can be produced by heating at 200 to 400° C. for 5 to 400 seconds.

The polyimide film of the present invention produced according to the above-described production method may have a dielectric loss factor (Df) of 0.004 or less, a thermal expansion coefficient (CTE) of 15 ppm/°C or less, and a glass transition temperature (Tg) of 340 ℃ above.

The present invention provides a multilayer film comprising the above-mentioned polyimide film and a thermoplastic resin layer, and a flexible metal foil laminate comprising the above-mentioned polyimide film and a conductive metal foil.

As the thermoplastic resin layer, for example, a thermoplastic polyimide resin layer or the like can be applied.

The metal foil to be used is not particularly limited, but when the flexible metal foil laminate of the present invention is used for electronic equipment or electrical equipment, for example, copper or copper alloys, stainless steel or alloys thereof, nickel may be included. Or nickel alloy (also including 42 alloy), aluminum or aluminum alloy metal foil.

Among common flexible metal foil laminates, copper foils called rolled copper foils and electrolytic copper foils are often used, and they can also be preferably used in the present invention. In addition, the surface of these metal foils may be coated with a rust-proof layer, a heat-resistant layer, or an adhesive layer.

In the present invention, the thickness of the metal foil is not particularly limited, and may be any thickness that can sufficiently function depending on the application.

The flexible metal foil laminate of the present invention can be laminated with metal foil on one side of the aforementioned polyimide film, or a thermoplastic polyimide-containing adhesive layer can be attached on one side of the aforementioned polyimide film. A structure in which the metal foil is laminated with the adhesive layer attached.

The present invention also provides an electronic component including the aforementioned flexible metal foil laminate as an electrical signal transmission circuit. The aforementioned electrical signal transmission circuit can be an electronic component that transmits signals at a high frequency of at least 2 GHz, in detail, at a high frequency of at least 5 GHz, and more specifically, at a high frequency of at least 10 GHz.

The aforementioned electronic component may be, for example, a communication circuit for a portable terminal, a communication circuit for a computer, or a communication circuit for an aerospace, but not limited thereto.

The functions and effects of the invention will be described in more detail below through specific embodiments of the invention. However, such an embodiment is merely presented as an example of the invention, and the right scope of the invention is not limited thereby.

[Example 1]

While injecting nitrogen into a 500-ml reactor equipped with a stirrer and a nitrogen injection/exhaust pipe, DMP was injected, and the temperature of the reactor was set to 30°C or lower, p-phenylenediamine was injected as a diamine component, and diamine was injected as a dianhydride component It was confirmed that benzophenone tetracarboxylic dianhydride and biphenyl tetracarboxylic dianhydride were completely dissolved. In a nitrogen atmosphere, the first polyamic acid having a viscosity of 200,000 cP at 23° C. was produced after the temperature was raised to 40° C. while stirring was continued for 120 minutes.

NMP was introduced while injecting nitrogen into a 500 ml reactor equipped with a stirrer and a nitrogen injection/exhaust pipe, and the temperature of the reactor was set to 30°C, then m-tolidine was introduced as a diamine component, and biphenyl was introduced as a dianhydride component. It was confirmed that tetracarboxylic dianhydride and pyromellitic dianhydride were completely dissolved. In a nitrogen atmosphere, the second polyamic acid having a viscosity of 200,000 cP at 23° C. was produced after the temperature was increased to 40° C. while stirring was continued for 120 minutes.

Next, the above-mentioned first polyamic acid and second polyamic acid were heated to 40°C while stirring continuously for 120 minutes under nitrogen atmosphere, and the final viscosity at 23°C was 200000cP, as shown in the following table 1. The third polyamic acid comprising a diamine component and a dianhydride component.

The third polyamic acid produced above was rotated at a high speed of 1,500 rpm or more to remove air bubbles. Then, the defoamed polyimide precursor composition was coated on the glass substrate using a spin coater. Then, it was dried at 120°C for 30 minutes in a nitrogen atmosphere to produce a gel film. The gel film was heated to 450°C at a rate of 2°C/min, and heat-treated at 450°C for 60 minutes at 2°C. It was cooled to 30 degreeC at the rate of /min, and the polyimide film was obtained.

Then, the polyimide film was peeled off from the glass substrate by dipping in distilled water.

The thickness of the produced polyimide film was 15 μm. The thickness of the produced polyimide film was measured using an Electric Film thickness tester from Anritsu.

[Examples 2 to 4 and Comparative Examples 1 and 2]

A polyimide film was produced in the same manner as in Example 1, except that the components and their contents in Example 1 were changed as shown in Table 1 below.

[Experimental Example 1 Evaluation of Dielectric Loss Factor, Thermal Expansion Coefficient and Glass Transition Temperature]

For the polyimide films produced in Examples 1 to 4, Comparative Example 1, and Comparative Example 2, respectively, the dielectric loss factor, thermal expansion coefficient, and glass transition temperature were measured, and the results are shown in Table 2 below.

[(1) Dielectric loss factor measurement]

Dielectric dissipation factor (Df) was measured using an Agilent 4294A ohmmeter with the flexible metal foil laminates placed for 72 hours.

[(2) Thermal expansion coefficient measurement]

Coefficient of Thermal Expansion (CTE) Using TA company thermal mechanism analyzer (thermomechanical analyzer) Q400 type, after cutting the polyimide film into width 4mm and length 20mm, under nitrogen atmosphere, a tension of 0.05N was applied at a speed of 10°C/min. The temperature was raised from room temperature to 300°C, and then cooled again at a rate of 10°C/min, and the slope in the range of 100°C to 200°C was measured at the same time.

[(3) Glass transition temperature measurement]

Glass transition temperature (Tg) The loss elastic modulus and storage elastic modulus of each thin film were obtained by DMA, and the inflection point was measured as the glass transition temperature in their tangent graphs.

As shown in Table 2, it can be confirmed that the polyimide films produced according to the examples of the present invention have a dielectric loss factor of 0.004 or less, which not only shows a significantly lower dielectric loss factor, but also has a thermal expansion coefficient and glass transition temperature of 0.004 or less. desired level.

This result is achieved according to the specific components and compounding ratios of the present invention, and it can be seen that the content of each component plays a decisive role.

On the contrary, the Examples are expected to be difficult to use in the polyimide films of Comparative Examples 1 and 2 having different compositions in terms of dielectric loss factor, thermal expansion coefficient, and glass transition temperature or more. High-frequency electronic components for signal transmission.

The above has been described with reference to the embodiments of the present invention, but as long as those skilled in the art to which the present invention pertains, they can make various applications and modifications within the scope of the present invention based on the foregoing content.

none.

Claims (7)

A polyimide film, the polyimide film includes a block copolymer, the block copolymer includes: a first block, the first block is made of benzophenone tetracarboxylic dianhydride and biphenyl tetracarboxylic acid A dianhydride component composed of dianhydride and a diamine component composed of p-phenylenediamine are obtained by imidization; and a second block, wherein the second block is composed of biphenyltetracarboxylic dianhydride and homophenylene A dianhydride component consisting of tetracarboxylic dianhydride and a diamine component consisting of m-tolidine are obtained by imidization, wherein the sum of the diamine components of the first block and the second block is The content of 100 mol % is the benchmark, the content of the aforementioned m-tolidine is more than 20 mol % and less than 35 mol %, and the content of the aforementioned p-phenylenediamine is more than 65 mol % and less than 80 mol %, and wherein , on the basis of the total content of the dianhydride components of the first block and the second block of 100 mol %, the content of the aforementioned benzophenone tetracarboxylic dianhydride is 10 mol % or more and 20 mol % or less, The content of the aforementioned biphenyltetracarboxylic dianhydride is 40 mol % or more and 60 mol % or less, and the content of the aforementioned pyromellitic dianhydride is 20 mol % or more and 45 mol % or less. The polyimide film according to claim 1, wherein the polyimide film has a dielectric loss factor of 0.004 or less, a thermal expansion coefficient of 16 ppm/°C or less, and a glass transition temperature of 300°C or more. A method for manufacturing a polyimide film, comprising the steps of: (a) polymerizing a first dianhydride component and a first diamine component in an organic solvent to produce a first polyamide acid; The step of producing the second polyamic acid by polymerizing the dianhydride component and the second diamine component in an organic solvent; (c) copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent and the step of making the third polyamic acid; and (d) the step of carrying out imidization of the precursor composition comprising the third polyamic acid after film-forming on the support; wherein, the first dianhydride component is composed of benzophenone tetracarboxylic dianhydride and biphenyl It is composed of tetracarboxylic dianhydride, the second dianhydride component is composed of biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, the first diamine component is composed of p-phenylenediamine, and the second diamine component is composed of p-phenylenediamine. It is composed of m-tolidine, wherein, based on the total content of the first diamine component and the second diamine component of 100 mol %, the content of the m-tolidine is more than 20 mol % and 35 mol %. % or less, the content of the aforementioned p-phenylenediamine is 65 mol % or more and 80 mol % or less, and wherein the total content of the aforementioned first dianhydride and the aforementioned second dianhydride components is 100 mol % as a benchmark, The content of the aforementioned benzophenone tetracarboxylic dianhydride is more than 10 mol % and less than 20 mol %, the content of the aforementioned biphenyl tetracarboxylic dianhydride is more than 40 mol % and less than 60 mol %, and the aforementioned pyromellitic acid The content of the dianhydride is 20 mol % or more and 45 mol % or less. The method for producing a polyimide film according to claim 3, wherein the polyimide film has a dielectric loss factor of 0.004 or less, a thermal expansion coefficient of 16 ppm/°C or less, and a glass transition temperature of 300°C or more. A multilayer film comprising the polyimide film as claimed in claim 1 or 2; and a thermoplastic resin layer. A flexible metal foil laminate, comprising the polyimide film as claimed in claim 1 or 2; and a conductive metal foil. An electronic component comprising the flexible metal foil laminate as claimed in claim 6.