KR20240080595A - Blended polyimide film and manufacturing method thereof - Google Patents

Abstract

The present invention provides a polyimide film having a dielectric constant (Dk) of 3.5 or less and a dielectric loss factor (Df) of 0.003 or less, measured at 10 GHz after being left for 24 hours in an environment of 85°C and 85%RH.

Description

Blended polyimide film and manufacturing method thereof}

The present invention relates to a blended polyimide film having excellent low dielectric properties and mechanical strength under a high temperature and high humidity environment and a method of manufacturing the same.

Polyimide (PI) is a polymer material that has the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials, based on an imide ring with a rigid aromatic main chain and excellent chemical stability. am.

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

Recently, as electronic products become lighter and smaller, highly integrated, flexible thin circuit boards are being actively developed.

These thin circuit boards tend to have a structure in which a circuit including metal foil is formed on a polyimide film that has excellent heat resistance, low temperature resistance, and insulation characteristics and is easy to bend.

Flexible metal clad laminates are mainly used as such thin circuit boards, and an example includes Flexible Copper Clad Laminate (FCCL), which uses a thin copper plate as a metal foil. In addition, polyimide is also used as a protective film and insulating film for thin circuit boards.

Meanwhile, as various functions have recently become embedded in electronic devices, fast calculation and communication speeds are required for the electronic devices, and to meet these requirements, thin circuit boards capable of high-speed communication at high frequencies are being developed.

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

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

In addition, it is known that the lower the dielectric properties of the insulator, the less likely it is to generate undesirable stray capacitance and noise in thin circuit boards, thereby eliminating many of the causes of communication delays.

Therefore, polyimide with low dielectric properties is recognized as an important factor in the performance of thin circuit boards.

In particular, in the case of high-frequency communication, dielectric loss inevitably occurs through polyimide. Dielectric dissipation factor (Df) refers to the degree of electrical energy wasted in a thin circuit board and is closely related to the signal transmission delay that determines the communication speed, so keeping the dielectric dissipation factor of polyimide as low as possible is also important for thin circuit boards. It is recognized as an important factor in the performance of the board.

Additionally, the more moisture contained in the polyimide film, the greater the dielectric constant and the higher the dielectric loss rate. In the case of polyimide film, while it is suitable as a material for thin circuit boards due to its excellent inherent properties, it may be relatively vulnerable to moisture due to the polar imide group, which may deteriorate its insulating properties.

Therefore, there is a need to develop a polyimide film that can maintain low dielectric properties while maintaining the mechanical properties unique to polyimide at a certain level even under high temperature or high humidity environments.

Republic of Korea Patent Publication No. 10-2021-0055230

Accordingly, in order to solve the above problems, the purpose of the present invention is to provide a blended polyimide film that has excellent low dielectric constant and improved mechanical strength even under a high temperature and high humidity environment and a method of manufacturing the same.

One embodiment of the present invention for achieving the above object has a dielectric constant (Dk) of 3.5 or less and a dielectric loss factor (Df) of 0.003 or less, measured at 10 GHz after being left for 24 hours in an environment of 85°C and 85%RH. A polyimide film is provided.

Another embodiment of the present invention provides a multilayer film including the polyimide film of the present disclosure.

Another embodiment of the present invention is the polyimide film of the present application; and an electrically conductive metal foil. It provides a flexible metal foil laminate including a.

Another embodiment of the present invention provides an electronic component including the flexible metal clad laminate of the present application.

As described above, the polyimide film of the present invention, manufactured by imidizing a polyamic acid solution composed of specific components and a specific composition ratio, maintains excellent low dielectric properties and mechanical strength even under high temperature and high humidity environments, and these properties are required. It can be usefully applied to various fields, especially electronic components such as flexible metal clad laminates.

Below, embodiments of the present invention will be described in more detail.

Prior to this, the terms or words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor should appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle of definability.

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

In this specification, singular expressions include plural expressions, unless the context clearly dictates otherwise. In this specification, terms such as “comprise,” “comprise,” or “have” are intended to designate the presence of implemented features, numbers, steps, components, or a combination thereof, and are intended to indicate the presence of one or more other features or It should be understood that this does not exclude in advance the possibility of the presence or addition of numbers, steps, components, or combinations thereof.

When amounts, concentrations, or other values or parameters are given herein as ranges, preferred ranges, or enumerations of upper preferred values and lower preferred values, any pair of upper range limits or It is to be understood that the preferred values and any lower range limits or all ranges formed from the preferred values are specifically disclosed.

When a range of numerical values is stated herein, unless otherwise stated, the range is intended to include the endpoints and all integers and fractions within the range. The scope of the invention is not intended to be limited to the specific values recited when defining the scope.

As used herein, “dianhydride acid” is intended to include precursors or derivatives thereof, which may not technically be dianhydride acids, but which will nonetheless react with diamines to form polyamic acids, which in turn will form polyamic acids. It can be converted to mead.

As used herein, “diamine” is intended to include precursors or derivatives thereof, which may not technically be diamines, but which will nonetheless react with dianhydride to form polyamic acids, which in turn will form polyamic acids. It can be converted to mead.

In this specification, “a to b” and “a to b” that indicate numerical ranges, “to” and “~” are defined as ≥ a and ≤ b.

The polyimide film according to the present invention may have a dielectric constant (Dk) of 3.5 or less and a dielectric loss factor (Df) of 0.003 or less as measured at 10 GHz after being left for 24 hours in an environment of 85°C and 85%RH.

For example, the dielectric constant measured after being left for 24 hours in an environment of 85°C and 85%RH may be 3.13 or more and 3.49 or less, and the dielectric loss rate may be 0.0026 or more and 0.0029 or less.

In other words, the polyimide film of the present application can maintain excellent low dielectric properties even under high temperature and high humidity environments.

In one embodiment, the polyimide film is composed of 1,4-phenylenebis(trimellitate monoester) dianhydride (p-phenylenebis(trimellitate anhydride), TAHQ) and biphenyltetracarboxylic dianhydride (3 It can be obtained by imidizing a polyamic acid solution containing a dianhydride component containing , 3, 4,4 -biphenyltetracarboxylic dianhydride (BPDA) and a diamine component containing m-tolidine (m-tolidine).

The polyimide chain derived from biphenyltetracarboxylic dianhydride (BPDA) has a structure named charge transfer complex (CTC), that is, an electron donor and an electron acceptor. has a regular straight structure located close to each other, and intermolecular interaction can be strengthened.

Since this structure has the effect of preventing hydrogen bonding with moisture, it has an effect on lowering the moisture absorption rate and can maximize the effect of lowering the hygroscopicity of the polyimide film.

In order for a polyimide film to simultaneously satisfy appropriate elasticity and moisture absorption, the content ratio of dianhydride is particularly important. For example, as the content ratio of biphenyltetracarboxylic dianhydride (BPDA) decreases, it may become difficult to expect a low moisture absorption rate due to the CTC structure.

In addition, the 1,4-phenylenebis(trimellitic acid monoester) dianhydride contains an ester bond, so it can contribute to improving the low dielectric properties of the polyimide film.

Meanwhile, the m-tolidine has a particularly hydrophobic methyl group, so it can contribute to the low moisture absorption characteristics of the polyimide film.

Moisture absorption rate is a ratio that represents the amount of moisture contained in a material, and it is generally known that when the moisture absorption rate is high, the dielectric constant and dielectric loss rate increase.

When water vapor or the like is absorbed into the polyimide film, water exists in a liquid state. In this case, the dielectric constant and dielectric loss rate of the polyimide film can increase dramatically.

In other words, the dielectric constant and dielectric loss rate of a polyimide film can drastically change with just a small amount of moisture absorption.

Therefore, the low dielectric properties of the polyimide film can be improved by improving the low moisture absorption properties of the polyimide film, and the dianhydride component and diamine component of the polyimide film of the present application contribute to the low dielectric and low moisture absorption properties of the polyimide film. You can contribute.

In one embodiment, the polyimide film according to the present invention has a mole percentage of 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ) based on 100 mole% of the total content of the dianhydride component. The ratio of the mole percent of the biphenyltetracarboxylic dianhydride (BPDA) to (the mole percent of the biphenyltetracarboxylic dianhydride (BPDA) / 1,4-phenylenebis (trimellitic acid monoester) ) The mole percent of dianhydride (TAHQ) may be 1.5 or more and 2.9 or less.

If the content of biphenyltetracarboxylic dianhydride (BPDA) is excessive or the content of 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ) is too low and exceeds the molar ratio, poly The low dielectric properties of the mid film may deteriorate.

Conversely, when the content of biphenyltetracarboxylic dianhydride (BPDA) is too low or the content of 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ) is too high and the molar ratio is lower than the molar ratio. , the mechanical strength of the polyimide film may decrease.

In one embodiment, the polyimide film according to the present invention may contain 10% by weight or more and 40% by weight or less of particulate polymer based on 100% by weight of the total weight of the polyimide film.

The particulate polymer may be a fluorine-based polymer or liquid crystal polymer (LCP).

The fluorine-based polymer is polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer. One or more types selected from the group consisting of polymer (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE/CTFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE) may be used. It is not limited.

Preferably, the fluorine-based polymer may be polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

If the particulate polymer exceeds the content range of the present application, the dielectric properties may be improved, but the mechanical properties of the polyimide film may deteriorate, and if the particulate polymer is below the content range of the present application, the low dielectric properties of the polyimide film may deteriorate. You can.

Additionally, the particulate polymer included in the polyimide film of the present application may have an average particle diameter of 15 μm or less and a glass transition temperature or melting point of 100°C or more.

In one embodiment, the moisture absorption rate of the polyimide film according to the present application may be 0.4% or less, and the tensile strength may be 150 MPa or more.

For example, the moisture absorption rate may be 0.28% or more and 0.38% or less, and the tensile strength may be 158 MPa or more and 199 MPa or less.

On the other hand, the polyimide film according to the present invention has a dielectric constant (Dk) of 3.5 or less, a dielectric loss factor (Df) of 0.002 or less measured at 10 GHz after being left for 24 hours in a 23°C environment, and a dielectric loss factor (Df) of 0.002 or less at 28GHz after being left for 24 hours in a 23°C environment. The dielectric constant (Dk) measured at 40 GHz is 3.5 or less, and the dielectric loss factor (Df) is 0.0029 or less. This may be less than 0.0029.

For example, after being left for 24 hours in a 23°C/50%RH environment, the dielectric constant (Dk) measured at 10 GHz may be 3.13 or more and 3.49 or less, and the dielectric loss factor (Df) may be 0.0014 or more and 0.00178 or less.

In addition, the dielectric constant (Dk) measured at 28GHz after being left for 24 hours in a 23℃ environment may be 3.13 or more and 3.49 or less, and the dielectric loss factor (Df) may be 0.00254 or more and 0.00285 or less, and after being left for 24 hours in a 23℃ environment, the dielectric constant (Dk) may be 3.13 or more and 3.49 or less. The dielectric constant (Dk) measured in may be 3.13 or more and 3.49 or less, and the dielectric loss factor (Df) may be 0.00257 or more and 0.00288 or less.

In other words, the polyimide film of the present invention has no difference between the dielectric constant measured at 10GHz after being left for 24 hours in an environment of 23℃/50%RH and the dielectric constant measured at 10GHz after being left for 24 hours in an environment of 85℃/85%RH. Low dielectric constant characteristics can be maintained despite changes in temperature and humidity.

The low dielectric constant characteristic of the polyimide film of the present invention was maintained without change even when the frequency changed during measurement.

In addition, the polyimide film of the present invention has a dielectric loss rate measured at 10GHz after being left for 24 hours in an environment of 85°C and 85%RH, but increases compared to the dielectric loss rate measured at 10GHz after being left for 24 hours in an environment of 23°C/50%RH. It can still exhibit low dielectric loss characteristics of 0.003 or less.

For example, the dielectric loss rate of the polyimide film of the present invention measured at 10 GHz after being left for 24 hours in an environment of 85°C and 85%RH is 90% higher than the dielectric loss rate measured at 10 GHz after being left for 24 hours in an environment of 23°C/50%RH. % or less (e.g., 60% or more, 86% or less), but can still exhibit low dielectric loss characteristics of 0.003 or less.

On the other hand, the polyimide film of the present invention has a dielectric loss rate measured at 28GHz and 40GHz after being left for 24 hours in a 23℃/50%RH environment compared to the dielectric loss rate measured at 10GHz after being left for 24 hours in a 23℃/50%RH environment. Although it increases, it can still exhibit low dielectric loss characteristics of 0.003 or less.

In this regard, in the case of the polyimide film of the present invention, which satisfies all moisture absorption, tensile strength, dielectric constant and dielectric loss rate, not only can it be used as an insulating film for flexible metal clad laminates, but also the manufactured flexible metal clad laminates transmit signals at high frequencies of 10 GHz or more. Even when used as an electrical signal transmission circuit, its insulation stability can be ensured and signal transmission delay can be minimized.

In one embodiment, the polyimide film of the present disclosure may be a random or block copolymer.

Meanwhile, the production of polyamic acid for producing the polyimide film of the present application is, for example,

(1) A method of polymerizing the entire amount of the diamine component in a solvent and then adding the dianhydride component in substantially equimolar amounts to the diamine component.

(2) A method of polymerizing the entire amount of the dianhydride component in a solvent, and then adding the diamine component in substantially equimolar amounts to the dianhydride component.

(3) After adding some of the diamine components into the solvent, mixing some of the dianhydride components in a ratio of about 95 to 105 mol% with respect to the reaction components, adding the remaining diamine components, and then adding the remaining dianhydride components continuously. A method of polymerizing by adding components so that the diamine component and dianhydride component are substantially equimolar.

(4) After adding the dianhydride component into the solvent, mixing some components of the diamine compound in a ratio of 95 to 105 mol% with respect to the reaction components, adding another dianhydride component, and then adding the remaining diamine component, A method of polymerizing the diamine component and the dianhydride component in substantially equal moles.

(5) reacting some diamine components and some dianhydride components in a solvent so that either one is in excess to form a first composition, and reacting some diamine components with some dianhydride components in another solvent so that any one is in excess, to form a first composition. 2 After forming the composition, the first and second compositions are mixed and polymerization is completed. In this case, if the diamine component is excessive when forming the first composition, the dianhydride component is added in excess in the second composition. When the dianhydride component is excessive in the first composition, the diamine component is excessive in the second composition, and the first and second compositions are mixed so that the total diamine component and dianhydride component used in these reactions are substantially equal. A method of polymerizing the molar mass may be included.

However, the polymerization method is not limited to the above examples, and of course, any known method can be used for producing the first and second polyamic acids.

In one embodiment, the method for producing a polyimide film according to the present invention includes biphenyltetracarboxylic dianhydride (BPDA) and 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ). It includes preparing a polyamic acid solution by polymerizing a dianhydride component containing a dianhydride component and a diamine component containing m-tolidine (mTB), and imidizing the polyamic acid solution.

In particular, the biphenyltetracarboxylic dianhydride relative to the mole percent of the 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ) based on 100 mole% of the total content of the dianhydride component. The mole percent of (BPDA) (the mole percent of biphenyltetracarboxylic dianhydride (BPDA)/the mole percent of 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ)) is 1.5 or more. , may be 2.9 or less.

A polyimide film can be manufactured by reacting the dianhydride component and the diamine component in a predetermined order and copolymerizing them.

Additionally, the polyimide production method may include adding 10% by weight to 40% by weight of particulate polymer to the polyamic acid solution and stirring. The particulate polymer may be a fluorine-based polymer or liquid crystal polymer (LCP).

In the present invention, the polymerization method of the polyamic acid as described above may be a random polymerization method, and the polyimide film manufactured from the polyamic acid of the present invention manufactured through the above process increases the tensile strength, moisture absorption rate, and dielectric strength. It can be preferably applied in terms of maximizing the effect of lowering the constant and dielectric loss rate.

However, since the above polymerization method produces a relatively short length of the repeating unit in the polymer chain described above, there may be limitations in demonstrating each of the excellent properties of the polyimide chain derived from the dianhydride component. Therefore, the polymerization method of polyamic acid that can be particularly preferably used in the present invention may be a block polymerization method.

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

The polyimide film manufactured according to the polyimide film manufacturing method has a moisture absorption rate of 0.4% or less, a tensile strength of 150 MPa or more, and a dielectric constant (Dk) measured after being left for 24 hours in an environment of 23°C/50%RH. may be 3.5 or less, and the dielectric loss factor (Df) may be 0.002 or less.

In particular, the polyimide film manufactured according to the polyimide film manufacturing method has a moisture absorption rate of 0.4% or less, a tensile strength of 150 MPa or more, and a dielectric constant ( Dk) may be 3.5 or less, and dielectric loss factor (Df) may be 0.003 or less.

In one embodiment according to the present invention, a multilayer film including the polyimide film, a multilayer film including the polyimide film and a thermoplastic resin layer, and a flexible metal clad laminate including the polyimide film and an electrically conductive metal foil. to provide.

The thermoplastic resin layer may be, for example, a thermoplastic polyimide resin layer.

There is no particular limitation on the metal foil to be used, but when using the flexible metal clad laminate of the present invention for electronic or electrical equipment, for example, copper or copper alloy, stainless steel or its alloy, nickel or nickel alloy (42 alloy) Also included), may be a metal foil containing aluminum or aluminum alloy.

In general flexible metal clad laminates, copper foils such as rolled copper foil and electrolytic copper foil are widely used, and can also be preferably used in the present invention. Additionally, a rust-prevention layer, a heat-resistant layer, or an adhesive layer may be applied to the surface of these metal foils.

In the present invention, the thickness of the metal foil is not particularly limited, and may be sufficient to provide sufficient function depending on the intended use.

The flexible metal clad laminate according to the present invention has metal foil laminated on one side of the polyimide film, or an adhesive layer containing thermoplastic polyimide is added to one side of the polyimide film, and the metal foil is attached to the adhesive layer. It may be a laminated structure.

Meanwhile, according to one embodiment of the present invention, it may be an electronic component including the flexible metal clad laminate as an electrical signal transmission circuit. The electrical signal transmission circuit may be an electronic component that transmits a signal at a high frequency of at least 2 GHz, specifically at a high frequency of at least 5 GHz, and more specifically at a high frequency of at least 10 GHz.

By controlling the high hygroscopicity of the polyimide film, which affects the electrical signal transmission loss, optimization of transmission loss can be achieved at a frequency of 10 GHz or higher.

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

Hereinafter, the operation and effects of the invention will be described in more detail through specific examples of the invention. However, these examples are merely presented as examples of the invention, and the scope of the invention is not determined by them.

Production example (production of polyimide film)

DMF was added while nitrogen was injected into a 500 ml reactor equipped with a stirrer and nitrogen injection/discharge pipes, the temperature of the reactor was set to 30°C, and 1,4-phenylenebis (trimellitic acid monoester) was added as the dianhydride component. The molar ratio of dianhydride (TAHQ) and biphenyltetracarboxylic dianhydride (BPDA) was adjusted to 1:1.5~2.9, and m-tolidine was added as a diamine component to ensure complete dissolution. Confirmed.

Afterwards, the temperature of the reactor was raised to 40°C under a nitrogen atmosphere and stirring was continued for 120 minutes while heating to prepare polyamic acid.

The content of the particulate polymer was added to the polyamic acid prepared in this way and dispersed by stirring. A polyimide precursor composition was prepared by adjusting the content of the catalyst and dehydrating agent, and then the polyimide was degassed on a glass substrate using a spin coater. The precursor composition was applied. Afterwards, a gel film was prepared by drying at a temperature of 120°C for 30 minutes under a nitrogen atmosphere, the gel film was heated to 450°C at a rate of 2°C/min, heat treated at 450°C for 60 minutes, and heated to 30°C for 2 minutes. A polyimide film was obtained by cooling at a rate of °C/min.

Examples 1 to 10 and Comparative Examples 1 to 4

The polyimide films of Examples 1 to 10 and Comparative Examples 1 to 4 were manufactured according to the manufacturing example described above, but by adjusting the content of the particulate polymer as shown in Table 1 below.

particulate polymer content
(weight%) Example 1 LCP 10 Example 2 LCP 20 Example 3 LCP 30 Example 4 LCP 40 Example 5 PTFE 10 Example 6 PTFE 20 Example 7 PTFE 30 Example 8 PFA 10 Example 9 PFA 20 Example 10 PFA 30 Comparative Example 1 LCP 50 Comparative example 2 PTFE 50 Comparative example 3 PFA 50 Comparative example 4 - 0

The tensile strength and moisture absorption rate of the polyimide films prepared in Examples 1 to 10 and Comparative Examples 1 to 4 were measured and shown in Table 2 below.

In addition, the dielectric constant (Dk) and dielectric loss factor (Df) of the polyimide films prepared in Examples 1 to 10 and Comparative Examples 1 to 4 were measured and are shown in Table 3 below.

Tensile strength (MPa) Moisture absorption rate (%) Example 1 199 0.38 Example 2 186 0.36 Example 3 173 0.34 Example 4 159 0.32 Example 5 194 0.36 Example 6 177 0.33 Example 7 158 0.29 Example 8 194 0.36 Example 9 177 0.32 Example 10 159 0.28 Comparative Example 1 146 0.30 Comparative example 2 123 0.22 Comparative Example 3 120 0.21 Comparative Example 4 212 0.50

23℃/50%, 24h
(10GHz) 23℃/50%, 24h
(28GHz) 23℃/50%, 24h
(40GHz) 85℃/85%, 24h
(10GHz) Dk Df Dk Df Dk Df Dk Df Example 1 3.49 0.00170 3.49 0.00280 3.49 0.00283 3.49 0.0029 Example 2 3.34 0.00160 3.34 0.00271 3.34 0.00275 3.34 0.0028 Example 3 3.31 0.00150 3.31 0.00263 3.31 0.00266 3.31 0.0027 Example 4 3.21 0.00140 3.21 0.00254 3.21 0.00257 3.21 0.0026 Example 5 3.43 0.00178 3.43 0.00285 3.43 0.00288 3.43 0.0029 Example 6 3.28 0.00175 3.28 0.00282 3.28 0.00286 3.28 0.0029 Example 7 3.14 0.00170 3.14 0.00279 3.14 0.00284 3.14 0.0028 Example 8 3.43 0.00175 3.43 0.00281 3.43 0.00284 3.43 0.0028 Example 9 3.28 0.00170 3.28 0.00280 3.28 0.00284 3.28 0.0028 Example 10 3.13 0.00165 3.13 0.00274 3.13 0.00277 3.13 0.0027 Comparative Example 1 3.13 0.00130 3.13 0.00243 3.13 0.00248 3.13 0.0025 Comparative example 2 2.84 0.00165 2.84 0.00275 2.84 0.00280 3.34 0.0027 Comparative Example 3 2.83 0.00160 2.83 0.00272 2.83 0.00276 3.31 0.0026 Comparative Example 4 3.58 0.00182 3.58 0.00290 3.58 0.00295 3.43 0.0032

The method of measuring the tensile strength, moisture absorption, dielectric constant (Dk), and dielectric loss factor (Df) of the produced polyimide film is as follows.

(1) Tensile strength measurement

The tensile strength of the sample was measured using a universal materials tester (model name: Instron 5564, Instron) using the method specified in ASTM D1708.

(2) Moisture absorption rate measurement

Two test pieces of polyimide film (4 cm wide, 25 cm long) were prepared and dried at 80°C for 1 hour. After drying, it was immediately placed in a constant temperature and humidity room at 23°C%RH, left for more than 24 hours, and calculated from the weight change before and after using the following equation.

Moisture absorption rate (% by weight) = [(Weight after moisture absorption - Weight after drying)/Weight after drying] Х100

(3) Dielectric constant measurement

The dielectric constant (Dk) was measured at 10 GHz, 28 GHz, and 40 GHz after leaving the polyimide film in an environment of 23°C/50%RH for 24 hours using an SPDR meter from Keysight.

In addition, the dielectric constant at 10 GHz was measured after the polyimide film was left in an environment of 85°C and 85%RH for 24 hours.

(4) Dielectric loss rate measurement

Dielectric loss factor (Df) was measured at 10 GHz, 28 GHz, and 40 GHz after leaving the polyimide film in an environment of 23°C for 24 hours using the cavity resonance method (SPDR) using Keysight's ENA (Vector Network Analyzer). The loss rate was measured.

In addition, the dielectric loss rate at 10 GHz was measured after the polyimide film was left in an environment of 85°C and 85%RH for 24 hours.

As shown in Table 2, the polyimide films manufactured according to Examples 1 to 10 of the present invention had a tensile strength of 150 MPa or more and a moisture absorption rate of 0.4% or less.

As shown in Table 3, the polyimide films of Examples 1 to 10 of the present invention had a dielectric constant (Dk) of 3.5 or less and a dielectric loss factor (Df) of 0.0020 or less measured at 10 GHz after being left for 24 hours in a 23°C environment. ) characteristics, as well as a dielectric constant (Dk) of 3.5 or less and a dielectric loss factor (Df) of 0.0030 or less measured at 10 GHz after being left for 24 hours even in a high temperature (85℃) and high humidity (85%) environment. Therefore, the low-dielectric properties were excellent.

In addition, the polyimide films of Examples 1 to 10 of the present invention were able to achieve dielectric constant (Dk) of 3.5 or less and dielectric loss factor (Df) of 0.0029 or less measured at 28 GHz after being left for 24 hours in a 23°C environment. , after being left for 24 hours in a 23°C environment, it was possible to achieve dielectric constant (Dk) of 3.5 or less and dielectric loss factor (Df) of 0.0029 or less measured at 40 GHz.

On the other hand, even though the dielectric constant (Dk) and dielectric loss factor (Df) of the polyimide films of Comparative Examples 1 to 3 were similar to those of the polyimide films of Examples 1 to 10, the tensile strength was less than 150 MPa.

That is, the polyimide films of Comparative Examples 1 to 3 were measured to have lower tensile strengths than the polyimide films of Examples 1 to 10 due to the use of an excessive amount of particulate polymer. Through this, it was confirmed that the mechanical properties of the polyimide film deteriorated when the content of the particulate polymer exceeded the range specified herein.

On the other hand, as in Comparative Example 4, when the particulate polymer was not used, the moisture absorption rate increased, the dielectric constant and dielectric loss rate increased, and the low dielectric properties deteriorated.

These measurement results suggest that in order to control the dielectric properties and mechanical properties to an appropriate level, it is preferable to include the particulate polymer in the content range selected in the present invention.

From this, it could be expected that the polyimide films of Examples 1 to 10 had excellent low dielectric constant properties and mechanical properties and were therefore suitable for actual application to electronic components.

Although the present invention has been described with reference to embodiments of the present invention, those skilled in the art will be able to make various applications and modifications based on the above contents within the scope of the present invention.

Claims (11)

The dielectric constant (Dk) measured at 10 GHz after being left for 24 hours in an 85°C, 85%RH environment is 3.5 or less and the dielectric loss factor (Df) is 0.003 or less.
Polyimide film.
According to paragraph 1,
The polyimide film is composed of a dianhydride component including 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ) and biphenyltetracarboxylic dianhydride (BPDA) and m-tolidine (m Obtained by imidizing a polyamic acid solution containing a diamine component containing -tolidine),
Polyimide film.
According to paragraph 2,
The biphenyltetracarboxylic dianhydride (BPDA) relative to the mole percent of the 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ) based on 100 mol% of the total content of the dianhydride component. ) mole % ratio (mol % of biphenyltetracarboxylic dianhydride (BPDA)/mol % of 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ)) is 1.5 or more. , which is 2.9 or less,
Polyimide film.
According to paragraph 2,
Containing 10% by weight or more and 40% by weight or less of particulate polymer based on 100% by weight of the total weight of the polyimide film,
Polyimide film.
According to paragraph 4,
The particulate polymer is polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer. At least one selected from the group consisting of polymer (ETFE), tetrafluoroethylene-chlorotrifluoroethylene copolymer (TFE/CTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), and liquid crystal polymer (LCP) Including,
Polyimide film.
According to paragraph 1,
The moisture absorption rate is less than 0.4%,
A tensile strength of 150 MPa or more,
Polyimide film.
According to paragraph 1,
The dielectric constant (Dk) measured at 10 GHz after being left for 24 hours in a 23°C environment is 3.5 or less, and the dielectric loss factor (Df) is 0.002 or less.
After being left for 24 hours in a 23°C environment, the dielectric constant (Dk) measured at 28GHz is 3.5 or less, and the dielectric loss factor (Df) is 0.0029 or less.
The dielectric constant (Dk) measured at 40 GHz after being left for 24 hours in a 23°C environment is 3.5 or less and the dielectric loss factor (Df) is 0.0029 or less.
Polyimide film.
Comprising the polyimide film of any one of claims 1 to 7,
Multilayer film.
According to clause 8,
Additionally comprising a thermoplastic resin layer,
Multilayer film.
The polyimide film of any one of claims 1 to 7; and
Containing: electrically conductive metal foil;
Flexible metal foil laminate.
Containing a flexible metal clad laminate according to paragraph 10,
Electronic parts.