KR102202484B1 - Polyimide film, flexible metal foil clad laminate comprising the same and manufacturing method of polyimide film - Google Patents

Abstract

The present invention relates to a polyimide film having a low dielectric loss factor (Df), a flexible metal clad laminate including the same, and a method for producing a polyimide film having a low dielectric loss factor (Df), wherein the polyimide film of the present invention is pyromellitic dianhydride. It is prepared by imidizing a final polyamic acid containing a first polyamic acid including a first block derived from (PMDA) and m-tolidine, and the average molecular weight of the first block is 20,000 g/mol It is characterized by the following.

Description

Polyimide film, a method of manufacturing a flexible metal foil laminate comprising the same, and a polyimide film {POLYIMIDE FILM, FLEXIBLE METAL FOIL CLAD LAMINATE COMPRISING THE SAME AND MANUFACTURING METHOD OF POLYIMIDE FILM}

The present invention relates to a polyimide film, and more particularly, to a polyimide film having a low dielectric loss factor (Df), a flexible metal clad laminate including the same, and a method of manufacturing a polyimide film having a low dielectric loss factor (Df).

In general, polyimide (PI) is based on an imide ring that has excellent chemical stability with a rigid aromatic backbone, and has the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials. Eggplant is a polymer material. The polyimide film produced therefrom is in the spotlight as an insulating material for electronic components that require the above-described characteristics, and in fact, it is a thin circuit board with high circuit integration and flexibility, in a broader sense, the flexible metal foil clad laminate. It is widely used as an insulating film.

On the other hand, in recent years, as various functions are embedded in electronic devices, high computational speed and communication speed are required in electronic devices, and in order to meet this demand, a thin circuit board capable of high-speed communication at a high frequency of 2 GHz or higher has been developed.

However, in the case of high-frequency communication of 2 GHz or higher, there is a problem that dielectric dissipation through the polyimide film inevitably occurs. More specifically, the dielectric dissipation factor (Df) refers to the degree of wasted electrical energy of the thin circuit board, and is closely related to the signal transmission delay that determines the communication speed.The dielectric loss factor (Df) of the polyimide film ) As low as possible is acting as an important factor in the performance of the thin circuit board.

Therefore, it is necessary to develop a polyimide film having a low dielectric loss factor (Df) while maintaining the existing mechanical properties and chemical resistance of the polyimide film at the highest level.

The matters described in the background art are provided to help understanding the background of the invention, and may include matters other than the prior art already known to those of ordinary skill in the field to which this technology belongs.

Korean Patent Publication No. 10-2019-0017527

Accordingly, in order to solve the above problems, the present invention provides a polyimide film having a low dielectric loss rate (Df), a flexible metal clad laminate including the same, and a method of manufacturing a polyimide film having a low dielectric loss rate (Df) by controlling the molecular weight. There is a purpose to do.

The polyimide film of the present invention to achieve the above object is a final comprising a first polyamic acid comprising a first block derived from pyromellitic dianhydride (PMDA) and m-tolidine (m-tolidine) It is prepared by imidizing polyamic acid, and characterized in that the average molecular weight of the first block is 20,000 g/mol or less.

The present invention provides a polyimide film having a low dielectric loss factor (Df) through molecular weight control, thereby providing a flexible metal clad laminate that can be applied to an electrical transmission circuit capable of communicating at a high frequency of at least 2 GHz or more, and further, a 5G band. .

The terms or words used in this specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Therefore, the configuration of the embodiments described in the present specification is only one of the most preferred embodiments of the present invention, and does not represent all of the technical spirit of the present invention, and various equivalents and modifications that can replace them at the time of application It should be understood that examples may exist.

In the present specification, expressions in the singular include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise", "include" or "have" are intended to designate the presence of implemented features, numbers, steps, components, or a combination thereof, and one or more other features or It is to be understood that the possibility of the presence or addition of numbers, steps, elements, or combinations thereof is not preliminarily excluded.

In the present specification, "dianhydride" is intended to include a precursor or derivative thereof, which may not be technically a dianhydride, but nevertheless will react with diamine to form a polyamic acid, which polyamic acid is again polyamic acid. Can be converted to mid.

Where an amount, concentration, or other value or parameter herein is given as an enumeration of a range, a preferred range or a preferred upper and lower preferred value, any pair of any upper range limits, or It is to be understood that the preferred values and any lower range limits or all ranges formed with preferred values are specifically disclosed.

Ranges of numerical values are intended to include the endpoints and all integers and fractions within that range, unless stated otherwise, when a range is referred to herein. It is intended that the scope of the invention is not limited to the specific values recited when defining the range.

First aspect: polyimide film

The present invention includes a polyimide film. It will be described in more detail below.

The polyimide film of the present invention already contains a final polyamic acid comprising a first polyamic acid comprising a first block derived from pyromellitic dianhydride (PMDA) and m-tolidine. It is manufactured by making it.

Here, the average molecular weight of the first block is preferably 20,000 g/mol or less, more preferably 15,000 g/mol or less, and still more preferably 10,000 g/mol.

This is because a polyimide film having a small average molecular weight is excellent in terms of dielectric loss factor (Df), and the polyimide film of the present invention having an average molecular weight of 20,000 g/mol or less in the first block satisfies a dielectric loss factor (Df) of 0.005 or less. .

In addition, the number of repeating units (or degree of polymerization) of the first block is preferably an integer of 5 to 55, more preferably 5 to 40, and even more preferably 5 to 30.

This is because, as described above, a polyimide film having a small number of repeating units and a small average molecular weight is excellent in terms of dielectric loss factor (Df), and the polyimide film of the present invention having a repeating unit number of 5 to 55 in the first block has a dielectric loss rate (Df) satisfies 0.005 or less.

On the other hand, if the average molecular weight and the number of repeating units of the first block are too small, there may be limitations in exhibiting the excellent properties of the polyimide other than the dielectric loss rate (Df), so the average molecular weight is at least 2,000 g/mol or more, It is preferable that the number is 5 or more.

In order to prepare the polyimide film of the present invention that satisfies the above conditions, the first polyamic acid has a molar ratio of pyromellitic dianhydride (PMDA) and m-tolidine of 0.86:1 to 0.98:1, more preferably It is preferable to satisfy 0.86:1 to 0.975:1, more preferably 0.86:1 to 0.97:1.

Meanwhile, it is preferable that the final polyamic acid further includes a second polyamic acid including a second block derived from dianhydride and m-tolidine.

More specifically, the second block is biphenyl-tetracarboxylic acid dianhydride (BPDA), oxydiphthalic anhydride (4,4'-oxidiphthalic anhydride, ODPA), and benzophenone tetracarboxylic acid. It is preferable to be derived from at least one dianhydride selected from dianhydride (3,3',4,4'-benzophenone tetracarboxylic dianhydride, BTDA) and m-tolidine, but the type of dianhydride is not particularly limited thereto.

The final polyamic acid comprising the first polyamic acid and the second polyamic acid is the sum of the dianhydride (PMDA) of the first polyamic acid and the dianhydride (BPDA) of the second polyamic acid and the molar ratio of m-tolidine is 0.96: It is preferable to satisfy 1 to 0.98:1, and more preferably to satisfy 0.97:1. After that, a final molar ratio of 0.995 to 0.997:1 is formed using a PMDA solution.

Here, m-tolidine includes m-tolidine contained in the first polyamic acid and the second polyamic acid.

In addition, the viscosity of the final polyamic acid is preferably 190,000 cP to 210,000 cP, more preferably 200,000 cP. The viscosity of the first polyamic acid and the second polyamic acid is also preferably 190,000 cP to 210,000 cP, and more preferably 200,000 cP.

The polyimide film of the present invention described so far satisfies the dielectric loss factor (Df) of 0.005 or less, more preferably 0.0045 or less, and still more preferably 0.004 or less.

The dielectric loss factor (Df) is generally used as an index indicating the ease of dissipation (dielectric loss), and the higher the dielectric loss rate (Df), the more easily the charge is lost, and on the contrary, the lower the dielectric loss rate (Df), the higher the charge is. It can be difficult to lose. That is, dielectric loss rate (Df) is a measure of power loss. As the dielectric loss rate (Df) is lower, the communication speed can be maintained faster while the signal transmission delay due to power loss is reduced. This is a strong requirement.

Therefore, the polyimide film of the present invention, which satisfies at least 2GHz or more, and furthermore, a dielectric loss factor (Df) of 0.005 or less, more specifically 0.0045 or less, and more specifically 0.004 or less under high frequency in 5G band, is It is possible to provide a flexible metal foil laminate that can be applied to an electrical transmission circuit capable of communication.

Second aspect: manufacturing method of polyimide film

The present invention includes a method for producing a polyimide film. It will be described in more detail below.

The manufacturing method of the polyimide film of the present invention includes (a) a first block derived by polymerizing pyromellitic dianhydride (PMDA) and m-tolidine in an organic solvent. Preparing polyamic acid, (b) biphenyl-tetracarboxylic acid dianhydride (BPDA), oxydiphthalic anhydride (4,4'-oxidiphthalic anhydride, ODPA), and benzophenone tetracar. A second block derived by polymerizing at least one dianhydride selected from among hexalic dianhydrides (3,3',4,4'-benzophenone tetracarboxylic dianhydride, BTDA) and m-tolidine in an organic solvent It proceeds including the step of preparing a second polyamic acid including and (c) imidizing the final polyamic acid including the first polyamic acid and the second polyamic acid prepared above.

In step (a), the molar ratio of pyromellitic dianhydride (PMDA) and m-tolidine is 0.86:1 to 0.98:1, more preferably 0.86:1 to 0.975:1, and even more preferably 0.86:1 to It is desirable to satisfy 0.97:1.

In step (c), the final polyamic acid comprising the first polyamic acid and the second polyamic acid is the sum of the dianhydride of the first polyamic acid (PMDA) and the dianhydride of the second polyamic acid and the molar ratio of m-tolidine It is preferable to satisfy 0.96:1 to 0.98:1, and more preferably to satisfy 0.97:1. Here, m-tolidine includes m-tolidine contained in the first polyamic acid and the second polyamic acid.

In steps (a) and (b), the first polyamic acid or the second polyamic acid may be prepared by a random polymerization method or a block polymerization method, but the polymerization method is not particularly limited thereto. .

In steps (a) and (b), the organic solvent is preferably an organic polar solvent, more preferably an aprotic polar solvent, specifically N,N-dimethylformamide (DMF), N, It is preferable to be at least one solvent selected from N-dimethylacetamide, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme, but the type of solvent is particularly limited thereto. no.

On the other hand, in step (a), step (b) or step (c), a separate filler may be further added for the purpose of improving various properties of the polyimide film, such as sliding properties, thermal conductivity, corona resistance, and loop hardness. have. More specifically, at least one filler selected from silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica may be added.

The average particle diameter of such a filler can be determined according to the characteristics of the polyimide film to be improved and the type of filler, but considering the reduction in mechanical properties due to the modification effect and surface property damage, 0.05 to 100 μm, more preferably 0.1 It is preferably in the range of 75 µm, more preferably 0.1 to 50 µm.

In addition, the amount of the filler added can also be determined according to the properties of the polyimide film to be improved and the type of filler, but considering the modification effect and the decrease in mechanical properties, 0.01 to 100 parts by weight per 100 parts by weight of the polyimide film, more It is preferably contained in an amount of 0.015 to 90 parts by weight, more preferably 0.02 to 80 parts by weight.

Meanwhile, in step (c), the final polyamic acid is preferably prepared by copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent, and after forming a film of the final polyamic acid prepared in this way on a support, imidization is performed. It is desirable to proceed.

As a method of imidizing the final polyamic acid, a thermal imidization method or a chemical imidization method may be applied, and a method in which a thermal imidization method and a chemical imidization method are combined may be applied. Here, the thermal imidization method is a method of inducing an imidation reaction with a heat source such as hot air or an infrared dryer, excluding a chemical catalyst, and the chemical imidization method is a method using a dehydrating agent and an imidizing agent.

When applying the thermal imidization method, it is preferable to induce the imidation reaction at a temperature of 100 to 600°C, more preferably 200 to 500°C, and even more preferably 300 to 500°C.

Third aspect: flexible metal foil laminate

The present invention includes a flexible metal foil laminate comprising the polyimide film of the present invention described above and an electrically conductive metal foil. It will be described in more detail below.

The electrically conductive metal foil is preferably made of at least one metal selected from copper, stainless steel, nickel, and aluminum, or an alloy containing the same, and most preferably copper foil, but is not particularly limited thereto.

A rust prevention layer, a heat-resistant layer, or an adhesive layer may be applied to the surface of the metal foil, and the thickness of the metal foil may be any thickness capable of exhibiting a sufficient function depending on the application.

The flexible metal foil laminate of the present invention has a structure in which a metal foil is laminated on one side of a polyimide film, or an adhesive layer containing a thermoplastic polyimide is included on one side of the polyimide film, and the metal foil is laminated thereto. Can be

Hereinafter, the action and effect of the invention will be described in more detail through specific embodiments of the invention. However, these embodiments are only presented as examples of the invention, and the scope of the invention is not limited thereby.

Preparation Example: Preparation of polyimide film

NMP was added while injecting nitrogen into a 500ml reactor equipped with a stirrer and a nitrogen injection/discharging tube, and after setting the temperature of the reactor to 30°C, PMDA and m-tolidine were added to completely dissolve. Thereafter, stirring was continued for 120 minutes while raising the temperature of the reactor to 40° C. in a nitrogen atmosphere to prepare a first polyamic acid having a viscosity at 23° C. of 500 to 2,500 cP. The first polyamic acid thus prepared includes a first block derived by polymerizing PMDA and m-tolidine.

Thereafter, it was the same as the method of preparing the first polyamic acid, but BPDA was added instead of PMDA to prepare a second polyamic acid.

When preparing the second polyamic acid, the amount of BPDA and m-tolidine was added so that the sum of the dianhydrides (PMDA and BPDA) of the final polyamic acid and the molar ratio of m-tolidine was 0.97:1. After that, a final molar ratio of 0.995 to 0.997:1 is formed using a PMDA solution. The second polyamic acid thus prepared comprises a second block derived by polymerizing BPDA and m-tolidine.

Subsequently, the first polyamic acid prepared above and the second polyamic acid were mixed, the temperature of the reactor was raised to 40° C. in a nitrogen atmosphere, and stirring was continued for 120 minutes while heating to a final polyamic acid having a final viscosity of 200,000 cP at 23° C. Was prepared. The viscosity and the molar ratio of the dianhydride and diamine were adjusted using a PMDA solution, and the final molar ratio was formed from 0.995 to 0.997:1.

The final polyamic acid thus prepared was removed from air bubbles through high-speed rotation of 1,500 rpm or more, and then coated on a glass substrate using a spin coater. Thereafter, a gel film was prepared by drying at a temperature of 120° C. for 30 minutes under a nitrogen atmosphere, which was heated up to 450° C. at a rate of 2° C./min, heat-treated at 450° C. for 60 minutes, and then 2 to 30° C. By cooling again at a rate of °C/min, a final polyimide film was obtained, dipping in distilled water, and peeling from the glass substrate.

Examples and Comparative Examples

It was prepared according to the above-described preparation example, but the molar ratio of PMDA and m-tolidine was adjusted when preparing the first polyamic acid so that the average molecular weight of the first block had the values shown in Table 1 below.

The molar ratio of PMDA and m-tolidine takes into account the molecular weight of PMDA (about 218 g/mol) and the molecular weight of m-tolidine (about 212 g/mol), and the molecular weight at which two water molecules escape by dehydration during their polymerization reaction (about 218 g/mol) 36g/mol), calculate the unit body molecular weight (about 394.42g/mol) of the first block, and divide the average molecular weight of the target first block by the unit body molecular weight of the first block calculated previously, and the number of repeating units (degree of polymerization) After obtaining, it was calculated by applying it to the Carothers equation. And after the production of the polyimide films of Examples 1 to 4 and Comparative Examples 1 to 4, it was confirmed to have an average molecular weight of the target first block.

division Average molecular weight of the first block [g/mol] Molar ratio of PMDA and m-tolidine Example 1 3,000 0.869: 1 Example 2 5,000 0.921: 1 Example 3 8,000 0.951: 1 Example 4 10,000 0.961: 1 Comparative Example 1 30,000 0.987: 1 Comparative Example 2 40,000 0.990: 1 Comparative Example 3 50,000 0.992: 1 Comparative Example 4 60,000 0.993: 1

Table 2 below shows the dielectric loss factor (Df) of the polyimide films of Examples 1 to 4 and Comparative Examples 1 to 4 prepared above, and the dielectric loss factor (Df) is measured by rolling copper foil on both sides of the polyimide film- After performing the two-roll lamination to prepare a flexible metal foil laminate, this was measured by standing for 72 hours using an ohmmeter Agilent 4294A.

division Dielectric loss factor (Df) Example 1 0.0035 Example 2 0.0038 Example 3 0.0042 Example 4 0.0045 Comparative Example 1 0.0055 Comparative Example 2 0.0063 Comparative Example 3 0.0072 Comparative Example 4 0.0083

As shown in Table 2, the polyimide film of Examples 1 to 4 satisfies the dielectric loss factor (Df) of 0.005 or less, and is applicable to an electrical transmission circuit in which signal transmission is performed at high frequency, whereas the polyimide films of Comparative Examples 1 to 4 Since the polyimide film has a relatively high dielectric loss factor (Df), it can be expected to be difficult to apply to the same.

Examples of the polyimide film of the present invention, a method of manufacturing a flexible metal foil laminate comprising the same, and a polyimide film are preferred embodiments that enable those skilled in the art to easily implement the present invention. However, since it is not limited to the above-described embodiment, this does not limit the scope of the present invention. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims. In addition, it will be apparent to those skilled in the art that various substitutions, modifications and changes are possible within the scope of the technical spirit of the present invention, and it is obvious that parts that can be easily changed by those skilled in the art are included in the scope of the present invention. .

Claims (12)

It is prepared by imidizing a final polyamic acid containing a first polyamic acid containing a first block derived only from pyromellitic dianhydride (PMDA) and m-tolidine,
The number average molecular weight of the first block is 20,000 g/mol or less,
Polyimide film, characterized in that the dielectric loss factor (Df) is 0.005 or less. The method of claim 1,
Polyimide film, characterized in that the number of repeating units of the first block is an integer of 5 to 55. The method of claim 1,
The polyimide film, characterized in that the molar ratio of the pyromellitic dianhydride (PMDA) and the m-tolidine is 0.86:1 to 0.98:1. The method of claim 1,
The final polyamic acid,
At least one dianhydride selected from biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA) and m-tolidine ) A polyimide film further comprising a second polyamic acid comprising a second block derived from. The method of claim 4,
The final polyamic acid,
Polyimide film, characterized in that the molar ratio of the sum of the dianhydride and m-tolidine is 0.96:1 to 0.98:1. The method of claim 1,
The viscosity of the final polyamic acid is a polyimide film, characterized in that 190,000cP to 210,000cP. The method of claim 4,
The first polyamic acid and the second polyamic acid have a viscosity of 190,000 cP to 210,000 cP. delete The polyimide film of any one of claims 1 to 7; And
A flexible metal foil laminated plate comprising an electrically conductive metal foil. In the method of producing a polyimide film,
(a) preparing a first polyamic acid comprising a first block derived by polymerizing only pyromellitic dianhydride (PMDA) and m-tolidine in an organic solvent;
(b) at least one dianhydride selected from biphenyltetracarboxylic dianhydride (BPDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA) and m-tolidine ( preparing a second polyamic acid comprising a second block derived by polymerizing m-tolidine) in an organic solvent; And
(c) imidizing the final polyamic acid including the first polyamic acid and the second polyamic acid,
The number average molecular weight of the first block is 20,000 g/mol or less,
The method for producing a polyimide film, characterized in that the dielectric loss factor (Df) of the polyimide film is 0.005 or less. The method of claim 10,
In step (a),
The method for producing a polyimide film, characterized in that the molar ratio of the pyromellitic dianhydride (PMDA) and the m-tolidine is 0.86:1 to 0.98:1. The method of claim 10,
In step (c),
The final polyamic acid,
A method for producing a polyimide film, characterized in that the molar ratio of the sum of the dianhydride and m-tolidine is 0.96:1 to 0.98:1.