KR102773837B1 - Polyimide Film and Method for Preparing the Same - Google Patents

Abstract

The present invention provides a polyimide film comprising a polyimide comprising a dianhydride monomer and a diamine monomer as polymerization units, wherein the dianhydride monomer comprises benzophenone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, and pyromellitic dianhydride, and the diamine monomer comprises oxydianiline, paraphenylene diamine, and 3,5-diaminobenzoic acid, and having an adhesive strength of 1.2 kgf/cm or more and an average value of a coefficient of thermal expansion (CTE) in the machine direction (MD) and a coefficient of thermal expansion (CTE) in the transverse direction (TD) of less than 13 ppm/℃, and a method for manufacturing the same.

Description

Polyimide film and method for preparing the same {Polyimide Film and Method for Preparing the Same}

The present invention relates to a polyimide film having improved mechanical properties, thermal properties and adhesive properties and a method for producing the same.

Polyimide (PI) is a thermally stable polymer material based on a rigid aromatic backbone, and has excellent mechanical strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring.

In addition, it is attracting attention as a high-functional polymer material in fields such as microelectronics and optics due to its excellent electrical properties such as insulating properties and low permittivity.

In the field of microelectronics, for example, due to the weight reduction and miniaturization of electronic products, highly integrated and flexible thin circuit boards are being actively developed, and accordingly, there is a trend to use polyimide, which has excellent heat resistance, low-temperature resistance, and insulation properties while also being easy to bend, as a protective film for thin circuit boards.

These thin circuit boards generally have a structure in which a circuit including a metal foil is formed on a polyimide film. These thin circuit boards are sometimes referred to as flexible metal clad laminates in a broad sense. As an example, when a thin copper plate is used as the metal foil, they are sometimes referred to as flexible copper clad laminates (FCCL) in a narrow sense.

Methods for manufacturing a flexible metal-clad laminate include, for example, (i) a casting method in which polyamic acid, a precursor of polyimide, is cast or applied on a metal foil and then imidized, (ii) a metallizing method in which a metal layer is directly formed on a polyimide film by sputtering or plating, and (iii) a lamination method in which a polyimide film and a metal foil are bonded by heat and pressure using a thermoplastic polyimide.

The double lamination method has the advantage that the thickness range of the applicable metal foil is wider than that of the casting method, and the equipment cost is lower than that of the metallizing method. As the device for performing lamination, a roll lamination device that continuously laminates while feeding in roll-shaped materials, or a double belt press device, etc. are used. Among the above, from the viewpoint of productivity, the thermal roll lamination method using a thermal roll lamination device can be used more preferably.

However, in the case of laminates, since a thermoplastic resin is used for bonding the polyimide film and the metal foil as described above, in order to develop the heat-sealability of this thermoplastic resin, it is necessary to apply heat of 300°C or higher, or in some cases, 400°C or higher, which is close to or higher than the glass transition temperature (Tg) of the polyimide film, to the polyimide film.

In general, it is known that the storage modulus of a viscoelastic material such as a polyimide film decreases significantly in a temperature range exceeding the glass transition temperature compared to the storage modulus at room temperature.

That is, when lamination requiring high temperature is performed, the storage modulus of the polyimide film at high temperature may be significantly reduced, and under low storage modulus, the polyimide film is likely to become loose and not exist in a flat form after lamination is completed. In other words, in the case of lamination, it can be said that the dimensional change of the polyimide film is relatively unstable.

Another thing to note is that when the glass transition temperature of the polyimide film is significantly lower than the temperature at which lamination is performed. Specifically, in the above case, since the viscosity of the polyimide film is relatively high at the temperature at which lamination is performed, a relatively large dimensional change may occur, and accordingly, there is a concern that the appearance quality of the polyimide film may deteriorate after lamination.

In addition, when using a casting method, a method of manufacturing a three-layer polyimide film for a two-layer FPC by applying a polyamic acid solution to the surface of a polyimide film and drying (imidization) the same can be mentioned, but a process for manufacturing a polyimide film and a process for applying a polyamic acid solution to the surface of the polyimide film and drying (imidization) the same are required, and since the process becomes multiple, there are cases where the cost increases.

In addition, as a three-layer polyimide film for a two-layer FPC, a method can be exemplified in which a polyamic acid solution is simultaneously flowed onto a support in multiple layers, dried, peeled off from the support, and heat-treated to produce a three-layer polyimide film. However, there were cases in which the polyimide layer directly in contact with the support was partially attached to the support, or a difference in peel strength occurred between the polyimide layer in contact with the support and the polyimide layer on the opposite side.

Accordingly, there is a demand for a polyimide film that can simultaneously improve mechanical properties, thermal properties, and adhesive properties to solve the above problems.

(Prior Document 1) Republic of Korea Patent Publication No. 10-2019-0079944

Accordingly, in order to solve the above problems, the present invention aims to provide a polyimide film comprising specific components and a specific composition ratio and having excellent mechanical properties, thermal properties and adhesive properties, and a method for manufacturing the same.

According to one aspect of the present invention, a polyimide comprising a diamine monomer and a dihydride monomer as polymerization units is provided.

The above dianhydride monomers include benzophenonetetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA), and pyromellitic dianhydride (PMDA).

The above diamine monomers include 4,4′-oxydianiline (ODA), p-phenylenediamine (PPD) and 3,5-diaminobenzoic acid (DABA).

The adhesive strength is 1.2 kgf/cm or more,

A polyimide film is provided, wherein the average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) is less than 13 ppm/℃.

According to another aspect of the present invention, (a) a dianhydride monomer including benzophenonetetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA)) and pyromellitic dianhydride (PMDA),

A step of manufacturing a polyamic acid by polymerizing a diamine monomer including 4,4′-oxydianiline (ODA), p-phenylenediamine (PPD) and 3,5-diaminobenzoic acid (DABA) in an organic solvent; and

(b) a step of imidizing the polyamic acid;

The adhesive strength of the manufactured polyimide film is 1.2 kgf/cm or more, and the average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) is less than 13 ppm/℃.

A method for manufacturing a polyimide film is provided.

According to another aspect of the present invention, a multilayer film and a flexible metal foil laminate comprising the polyimide film and a thermoplastic resin layer or an electrically conductive metal foil are provided.

According to these aspects, the above-mentioned conventional problems can be solved, and the present invention has a practical purpose of providing specific embodiments thereof.

As described above, the present invention provides a polyimide film having excellent mechanical properties, thermal properties, and adhesive properties through a polyimide film composed of specific components and a specific composition ratio, and a method for manufacturing the same, so that the polyimide film can be usefully applied to various fields requiring these properties, particularly electronic components such as flexible metal-clad laminates.

Hereinafter, embodiments of the invention will be described in more detail in the order of “polyimide film” and “method for producing polyimide film” according to the present invention.

Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best way.

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 all of the technical ideas of the present invention, and it should be understood that various equivalents and modified examples may exist that can replace them at the time of filing this application.

In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises," "includes," or "has" are intended to specify the presence of a feature, number, step, component, or combination thereof implemented, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

When amounts, concentrations, or other values or parameters are given in this specification as a range, a preferred range, or an enumeration of an upper preferred value and a lower preferred value, it should be understood that this specifically discloses all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, whether or not ranges are separately disclosed.

When a range of numerical values is mentioned in this specification, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range. The scope of the present invention is not intended to be limited to the specific values mentioned when defining the range.

As used herein, "dianhydride" is intended to include precursors or derivatives thereof, which may not technically be dianhydrides, but which will nonetheless react with a diamine to form a polyamic acid, which polyamic acid can then be converted to a polyimide.

As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nonetheless react with a dianhydride to form a polyamic acid, which can then be converted to a polyimide.

In this specification, “a to b” and “a~b” indicating a numerical range are defined as “a to” and “~” as ≥ a and ≤ b.

A polyimide film according to the present invention comprises a polyimide comprising a dianhydride monomer and a diamine monomer as polymerization units, wherein the dianhydride monomer comprises benzophenonetetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA), and pyromellitic dianhydride (PMDA), and the diamine monomer may comprise oxydianiline (ODA), p-phenylenediamine (PPD), and 3,5-diaminobenzoic acid (DABA).

In addition, the polyimide film may have an adhesive strength of 1.2 kgf/cm or more, and an average value of a coefficient of thermal expansion (CTE) in the machine direction (MD) and a coefficient of thermal expansion (CTE) in the transverse direction (TD) may be less than 13 ppm/℃.

For example, the adhesive strength of the polyimide film may be 1.2 kgf/cm or more or 1.25 kgf/cm or more.

Additionally, the adhesive strength of the polyimide film may be 5.0 kgf/cm or less, 3.0 kgf/cm or less, or 1.5 kgf/cm or less.

The adhesive strength of the above polyimide film is such that the wide sides of the film are designated as side A and side B, respectively, and the A side and the B side can exhibit different adhesive strengths.

Meanwhile, the B side may represent a side that comes into contact with a belt of a belt dryer used in the imidization step during the manufacture of the polyimide film, and the A side may represent a side opposite to the B side that comes into contact with air in the imidization step.

The adhesive strength of the polyimide film can represent the peel strength with respect to the copper foil laminated on the A side and the B side of the polyimide film, respectively. That is, the adhesive strength of the polyimide film can represent the peel strength at which the adhesive layer and the copper foil are peeled by performing a peeling test in a structure in which an adhesive layer (bonding sheet, etc.) and a copper foil are sequentially laminated on the A side and the B side of the polyimide film, respectively.

Meanwhile, the average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) of the polyimide film may be less than 13 ppm/℃, less than 12.5 ppm/℃, or less than 12 ppm/℃.

Additionally, the average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) of the polyimide film may be 5 ppm/℃ or more, 6 ppm/℃ or more, 7 ppm/℃ or more, 8 ppm/℃ or more, or 9 ppm/℃ or more.

In one embodiment, based on 100 mol% of the total content of the dihydride monomer, the content of the benzophenone tetracarboxylic dianhydride may be 15 mol% or more and 35 mol% or less, the content of the biphenyl tetracarboxylic dianhydride may be 30 mol% or more and 50 mol% or less, and the content of the pyromellitic dianhydride may be 30 mol% or more and 50 mol% or less.

For example, based on 100 mol% of the total content of the above-mentioned dihydride monomers, the content of the benzophenone tetracarboxylic dianhydride may be 20 mol% or more and 25 mol% or less, the content of the biphenyl tetracarboxylic dianhydride may be 35 mol% or more and 45 mol% or less, and the content of the pyromellitic dianhydride may be 35 mol% or more and 45 mol% or less.

The polyimide chain derived from the biphenyltetracarboxylic dianhydride of the above dianhydride monomer has a structure called a charge transfer complex (CTC), i.e., a regular straight structure in which the electron donor and electron acceptor are positioned close to each other, and intermolecular interaction is strengthened.

In addition, the benzophenone tetracarboxylic dianhydride having a carbonyl group also contributes to the expression of CTC, similar to the biphenyl tetracarboxylic dianhydride.

In particular, the carbonyl group of the benzophenonetetracarboxylic dianhydride can contribute to improving the adhesive strength of the polyimide film.

The above-mentioned dianhydride monomer may include the above-mentioned pyromellitic dianhydride. The above-mentioned pyromellitic dianhydride is a dianhydride monomer having a relatively rigid structure, which is preferable in that it can provide appropriate elasticity to the polyimide film.

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

The increase in the content of the pyromellitic dianhydride in the above-mentioned dianhydride monomer can be understood as an increase in the imide group within the molecule based on the same molecular weight, and this can be understood as a relative increase in the proportion of the imide group derived from the pyromellitic dianhydride in the polyimide polymer chain compared to the imide group derived from the biphenyltetracarboxylic dianhydride and the benzophenonetetracarboxylic dianhydride.

If the content ratio of the above pyromellitic dianhydride is reduced too much, the component of a relatively rigid structure is reduced, and the mechanical properties of the polyimide film may deteriorate below the desired level.

Therefore, when the content of the biphenyltetracarboxylic dianhydride, the benzophenonetetracarboxylic dianhydride, and the pyromellitic dianhydride exceeds or falls below the range of the present invention, the mechanical properties, thermal properties, and adhesive properties of the polyimide film may deteriorate.

In one embodiment, based on 100 mol% of the total content of the diamine monomer, the content of the oxydianiline may be 35 mol% or more and 55 mol% or less, the content of the paraphenylene diamine may be 35 mol% or more and 55 mol% or less, and the content of the 3,5-diaminobenzoic acid may be 5 mol% or more and 15 mol% or less.

For example, based on 100 mol% of the total content of the diamine monomer, the content of the oxydianiline may be 40 mol% or more and 50 mol% or less, the content of the paraphenylene diamine may be 40 mol% or more and 55 mol% or less, and the content of the 3,5-diaminobenzoic acid may be 5 mol% or more and 10 mol% or less.

The above 3,5-diaminobenzoic acid is a monomer containing a hydrophilic functional group and can improve the adhesive strength of a polyimide film.

In addition, the above-mentioned oxydianiline and the above-mentioned paraphenylene diamine can improve the mechanical properties and thermal properties of the polyimide film.

Therefore, when the contents of the oxydianiline, the paraphenylene diamine and the 3,5-diaminobenzoic acid exceed or fall below the range of the present invention, the mechanical properties, thermal properties and adhesive properties of the polyimide film may deteriorate.

In one embodiment, the polyimide film of the present invention may have a strength of 300 MPa or more, an elastic modulus of 5.0 GPa or more, an elongation of 50% or more, and a glass transition temperature of 340°C or more.

For example, the strength of the polyimide film may be 310 MPa or more, 320 MPa or more, 330 MPa or more, 340 MPa or more, or 350 MPa or more. Meanwhile, the strength of the polyimide film may be 450 MPa or less, 400 MPa or less, or 370 MPa or less.

Additionally, the elastic modulus of the polyimide film may be 10 GPa or less, 7 GPa or less, or 6.5 GPa or less.

For example, the elongation of the polyimide film may be 55% or greater, 80% or less, 75% or less, 70% or less, or 65% or less.

Meanwhile, the glass transition temperature of the polyimide film may be 345°C or higher, 350°C or higher, or 400°C or lower, 370°C or lower, 365°C or lower, 360°C or lower, or 355°C or lower.

Meanwhile, the polyamic acid used to manufacture the polyimide film may have a time of 120 seconds or longer for the viscosity to reach 100,000 cP when the viscosity is measured using a viscometer after adding a catalyst and a dehydrating agent and removing air bubbles through high-speed rotation of 1,500 rpm or higher.

In one embodiment, the polyimide of the polyimide film may be a block copolymer having two or more blocks.

In one embodiment, the polyimide may be a copolymer comprising a block comprising the oxydianiline and the benzophenonetetracarboxylic dianhydride.

In another embodiment, the polyimide may be a copolymer comprising blocks comprising the oxydianiline, the benzophenonetetracarboxylic dianhydride, and the pyromellitic dianhydride.

The above-mentioned specific composition block can particularly improve the adhesion of the polyimide film.

In addition, when the block of the above-mentioned specific composition is not included, the adhesive strength of the polyimide film may decrease, and the average values of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) may increase.

In addition, the glass transition temperature of the polyimide film may be lowered or the film forming process may be degraded.

In the present invention, the production of polyamic acid is carried out, for example,

(1) A method of polymerizing by placing the entire diamine component in a solvent, and then adding the dianhydride component in a substantially equimolar amount with the diamine component;

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

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

(4) A method of polymerizing by adding a dianhydride component into a solvent, mixing some of the diamine compound components with the reaction components at a ratio of 95 to 105 mol%, adding other dianhydride components, and then continuously adding the remaining diamine components so that the diamine components and dianhydride components are substantially equimolar;

(5) A method of forming a first composition by reacting some of the diamine components and some of the dianhydride components in a solvent so that one is in excess, and forming a second composition by reacting some of the diamine components and some of the dianhydride components in another solvent so that one is in excess, and then mixing the first and second compositions and completing polymerization, wherein when the diamine component is in excess when forming the first composition, the dianhydride component is in excess in the second composition, and when the dianhydride component is in excess in the first composition, the diamine component is in excess in the second composition, and the first and second compositions are mixed so that the total diamine components and dianhydride components used in these reactions are substantially equimolar, and then polymerizing may be performed.

However, the polymerization method is not limited to the above examples, and it goes without saying that any known method can be used to manufacture polyamic acid.

In one specific example, the method for manufacturing a polyimide film according to the present invention comprises:

(a) a dianhydride monomer including benzophenonetetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA), and pyromellitic dianhydride (PMDA),

A method for producing a polyamic acid, comprising: a step of polymerizing a diamine monomer including 4,4'-oxydianiline (ODA), p-phenylenediamine (PPD), and 3,5-diaminobenzoic acid (DABA) in an organic solvent; and (b) a step of imidizing the polyamic acid; wherein the adhesive strength of the produced polyimide film is 1.2 kgf/cm or more, and an average value of a coefficient of thermal expansion (CTE) in the machine direction (MD) and a coefficient of thermal expansion (CTE) in the transverse direction (TD) is less than 13 ppm/℃.

In one embodiment, based on 100 mol% of the total content of the dihydride monomer, the content of the benzophenone tetracarboxylic dianhydride may be 15 mol% or more and 35 mol% or less, the content of the biphenyl tetracarboxylic dianhydride may be 30 mol% or more and 50 mol% or less, and the content of the pyromellitic dianhydride may be 30 mol% or more and 50 mol% or less.

In addition, based on 100 mol% of the total content of the diamine monomer, the content of the oxydianiline may be 35 mol% or more and 55 mol% or less, the content of the paraphenylene diamine may be 35 mol% or more and 55 mol% or less, and the content of the 3,5-diaminobenzoic acid may be 5 mol% or more and 15 mol% or less.

In one embodiment, the polyimide film may have a strength of 300 MPa or more, an elastic modulus of 5.0 GPa or more, an elongation of 50% or more, and a glass transition temperature of 340°C or more.

In one embodiment, the polyamic acid may be a copolymer comprising blocks comprising the oxydianiline and the benzophenonetetracarboxylic dianhydride.

In another embodiment, the polyamic acid may be a copolymer comprising blocks comprising the oxydianiline, the benzophenonetetracarboxylic dianhydride, and the pyromellitic dianhydride.

In the present invention, the polymerization method of the polyamic acid as described above can be defined as a block polymerization method, and a polyimide film manufactured from the polyamic acid of the present invention manufactured through the above process can be preferably applied in terms of maximizing the effects of the present invention of improving mechanical properties, thermal properties, and adhesive properties.

Meanwhile, the solvent for synthesizing polyamic acid is not particularly limited, and any solvent that dissolves polyamic acid can be used, but an amide solvent is preferable.

Specifically, the solvent may be an organic polar solvent, and specifically, an aprotic polar solvent, and may be, for example, at least one selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-pyrrolidone (NMP), p-chlorophenol, o-chlorophenol, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme, but is not limited thereto, and may be used alone or in combination of two or more as needed.

In one example, the solvent may be N,N-dimethylformamide and N,N-dimethylacetamide, which are particularly preferably used.

In addition, in the polyamic acid manufacturing process, fillers other than nano silica may be added for the purpose of improving various properties of the film, such as tackiness, thermal conductivity, corona resistance, and loop hardness. The fillers to be added are not particularly limited, but preferred examples include titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

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

If the particle size falls below this range, it becomes difficult to achieve a modification effect, and if it exceeds this range, the surface properties may be significantly damaged or the mechanical properties may be significantly deteriorated.

In addition, there is no particular limitation on the amount of filler to be added, and it may be determined based on the film properties to be modified, the particle size of the filler, etc. In general, the amount of filler to be added is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight, relative to 100 parts by weight of polyimide.

If the amount of filler added is below this range, it is difficult for the filler to exhibit a modifying effect, and if it exceeds this range, the mechanical properties of the film may be significantly damaged. The method of adding the filler is not particularly limited, and any known method may be used.

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

Additionally, it can be manufactured by a complex imidization method in which thermal imidization and chemical imidization are performed in parallel.

The above thermal imidization method is a method that excludes chemical catalysts and induces the imidization reaction using a heat source such as hot air or an infrared dryer.

The above thermal imidization method can imidize the amic acid group present in the gel film by heat-treating the gel film at a variable temperature in the range of 100 to 600°C, specifically, can imidize the amic acid group present in the gel film by heat-treating it at 200 to 500°C, more specifically, can imidize the amic acid group present in the gel film by heat-treating it at 300 to 500°C.

However, even during the process of forming a gel film, some of the amic acid (about 0.1 mol% to 10 mol%) may be imidized, and for this purpose, the polyamic acid composition may be dried at a variable temperature in the range of 50°C to 200°C, and this may also be included in the category of the thermal imidization method.

In the case of the chemical imidization method, a polyimide film can be manufactured using a dehydrating agent and an imidizing agent according to a method known in the art. The term "dehydrating agent" here means a substance that promotes a ring closure reaction through a dehydration action on a polyamic acid, and non-limiting examples thereof include aliphatic acid anhydrides, aromatic acid anhydrides, N,N'-dialkylcarbodiimides, halogenated lower aliphatic, halogenated lower fatty acid anhydrides, aryl phosphonic dihalides, and thionyl halides. Among these, aliphatic acid anhydrides may be preferable in terms of ease of acquisition and cost, and non-limiting examples thereof include acetic anhydride (or acetic anhydride, AA), propionic acid anhydride, and lactic acid anhydride, and these may be used alone or in combination of two or more.

In addition, the "imidizing agent" means a substance having an effect of promoting a ring-closing reaction for polyamic acid, and may be an imine component such as an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine, for example. Among these, a heterocyclic tertiary amine may be preferable from the viewpoint of reactivity as a catalyst. Non-limiting examples of heterocyclic tertiary amines include quinoline, isoquinoline, β-picoline (BP), pyridine, and the like, and these may be used alone or in combination of two or more.

The amount of the dehydrating agent added is preferably in the range of 0.5 to 5 mol per mol of the amic acid group in the polyamic acid, and particularly preferably in the range of 1.0 to 4 mol. In addition, the amount of the imidizing agent added is preferably in the range of 0.05 to 2 mol per mol of the amic acid group in the polyamic acid, and particularly preferably in the range of 0.2 to 1 mol.

If the amount of the dehydrating agent and the imidizing agent is below the above range, chemical imidization is insufficient, cracks may form in the polyimide film being manufactured, and the mechanical strength of the film may also be reduced. In addition, if the amount of these added exceeds the above range, imidization may proceed excessively quickly, and in this case, it is difficult to cast in a film form or the manufactured polyimide film may exhibit brittle characteristics, which is not preferable.

As an example of a complex imidization method, a polyimide film can be manufactured by adding a dehydrating agent and an imidizing agent to a polyamic acid solution, heating the solution at 80 to 200°C, preferably 100 to 180°C, to partially cure and dry it, and then heating the solution at 200 to 400°C for 5 to 400 seconds.

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

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

There is no particular limitation on the metal foil to be used, but when the flexible metal foil laminate of the present invention is used for electronic devices or electrical devices, for example, the metal foil may be copper or a copper alloy, stainless steel or an alloy thereof, nickel or a nickel alloy (including a 42 alloy), aluminum or an aluminum alloy.

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

In the present invention, there is no particular limitation on the thickness of the metal foil, and any thickness that can sufficiently exhibit a function depending on the intended use may be used.

The flexible metal foil laminate according to the present invention may have a structure in which a metal foil is laminated to 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 laminated while attached to the adhesive layer.

The present invention also provides an electronic component including the flexible metal foil laminate as an electrical signal transmission circuit.

Hereinafter, the operation and effect of the invention will be described in more detail through specific examples of the invention. However, these examples are presented only as examples of the invention, and the scope of the invention's rights is not determined thereby.

<Manufacturing Example>

While injecting nitrogen into a 500 mL reactor equipped with a stirrer and a nitrogen injection/discharge pipe, add DMF and set the temperature of the reactor to 30°C. Then, diamine monomers such as oxydianiline (ODA), paraphenylene diamine (PPD), and 3,5-diaminobenzoic acid (DABA), and dianhydride monomers such as biphenyltetracarboxylic dianhydride (BPDA), benzophenonetetracarboxylic dianhydride (BTDA), and pyromellitic dianhydride (PMDA) are added in the specified order and confirmed to be completely dissolved.

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

A catalyst and a dehydrating agent were added to the polyamic acid thus manufactured, and air bubbles were removed through high-speed rotation at 1,500 rpm or higher, and then the polyamic acid was applied to a glass substrate using a spin coater.

Thereafter, a gel film was produced by drying at 120°C for 30 minutes under a nitrogen atmosphere, which was then heated at a rate of 2°C/min to 450°C, heat-treated at 450°C for 60 minutes, and cooled again at a rate of 2°C/min to 30°C to obtain the final polyimide film, which was then peeled off from the glass substrate by dipping it in distilled water.

The thickness of the manufactured polyimide film was 15 ㎛. The thickness of the manufactured polyimide film was measured using an Electric Film Thickness Tester from Anritsu.

<Examples 1 to 3 and Comparative Examples 1 to 3>

It was manufactured according to the manufacturing example described above, but the contents of the diamine monomer and the dianhydride monomer were adjusted as shown in Table 1.

A polyimide film including blocks containing ODA, BTDA and PMDA of Examples 1 to 3 was manufactured by controlling the order and amount of addition of the diamine monomer and the dianhydride monomer.

Meanwhile, a polyimide film including blocks including ODA and PMDA of Comparative Examples 1 to 3 was manufactured by controlling the order and amount of addition of the diamine monomer and the dianhydride monomer.

That is, the polyimide films of Comparative Examples 1 to 3 do not include blocks including ODA, BTDA, and PMDA.

Main block structure Diamine monomer
(mole%) Idianhydride monomer
(mole%) ODA PPD DABA PMDA BPDA BTDA Example 1 Blocks including ODA, BTDA and PMDA 40 52 8 35 40 25 Example 2 47 45 8 45 40 25 Example 3 42 50 8 40 40 20 Comparative Example 1 Block including ODA and PMDA 40 52 8 34 46 20 Comparative Example 2 36 58 6 43 17 40 Comparative Example 3 40 52 8 34 46 20

<Experimental example: Evaluation of properties of polyimide film>

In order to evaluate the properties of the polyimide films manufactured in Examples 1 to 3 and Comparative Examples 1 to 3, respectively, elastic modulus, strength, elongation, glass transition temperature, adhesion, MD/TD average value CTE, and film forming processability were measured using the following methods, and the results are shown in Table 2 below.

(1) Elasticity, strength and elongation

Elastic modulus, strength, and elongation were measured using Instron (Instron 3365SER) equipment according to the ASTM D 882 measurement method.

(2) Measurement of glass transition temperature

The glass transition temperature (T _g ) was measured by obtaining the loss modulus and storage modulus of each film using DMA, and the inflection point in the tangent graph was measured as the glass transition temperature.

(3) Adhesion measurement

Double-sided FCCL was manufactured by laminating Inox Bonding Sheet (BSH-MX-25MP) and Iljin Copper Foil (ICS) in that order on both wide sides (A side and B side) of the manufactured polyimide film at a temperature of 180°C and a pressure of 30 MPa for 60 minutes.

That is, in the double-sided FCCL, a bonding sheet is laminated on the A side of the polyimide film, and copper foil is laminated on the bonding sheet. In addition, a bonding sheet is laminated on the B side of the polyimide film, similarly to the A side, and copper foil is laminated on the bonding sheet.

Meanwhile, the B side represents a side that comes into contact with the belt of a belt dryer used in the imidization step during the manufacture of a polyimide film, and the A side represents a side opposite to the B side that comes into contact with air in the imidization step.

The manufactured double-sided FCCL was peeled at 200 mm/min using Instron 3365SER equipment, and the peel strength of the bonding sheet and copper foil on each side (A side and B side) of the polyimide film was measured.

(4) MD/TD average CTE measurement

The coefficient of thermal expansion (CTE) was measured using a TA thermomechanical analyzer, model Q400. The polyimide film was cut to 4 mm in width and 20 mm in length, and then, under a nitrogen atmosphere, a tension of 0.05 N was applied. The temperature was increased from room temperature to 300°C at a rate of 10°C/min, and then cooled again at a rate of 10°C/min. The slope between 100°C and 200°C was measured to measure the CTE in the MD direction and the CTE in the TD direction.

Afterwards, the average values of the measured CTE in the MD direction and CTE in the TD direction were calculated.

(5) Measurement of the fairness of the filming process

A catalyst and a dehydrating agent were added to the polyamic acid of Examples 1 to 3 and Comparative Examples 1 to 3, and air bubbles were removed through high-speed rotation at 1,500 rpm or higher. The viscosity was measured using a viscometer (Thermo Scientific, HAAKE MARS40 Rheometers), and the time for the viscosity to reach 100,000 cP was measured.

If the time to reach 100,000 cP was 120 seconds or longer, it was rated as “high”, and if it was less than 120 seconds, it was rated as “low”.

If the film forming process is evaluated as “low,” the reaction (gelation speed) is too fast, so there is not enough time to apply the polyamic acid mixture (polyamic acid + catalyst + dehydrating agent) to the glass substrate, and gelation may occur during the spin coater operation, resulting in an uneven thickness formation.

Elasticity
(GPa) robbery
(MPa) Believer
(%) Tg
(℃) Adhesion
(kgf/cm)
A/B side MD/TD
Average CTE
(ppm/℃) Unveiling
Fairness Example 1 6.3 360 60 350 1.30 / 1.40 9.8 award Example 2 5.8 355 64 352 1.28 / 1.27 11.9 award Example 3 6.2 350 59 350 1.41 / 1.34 10.2 award Comparative Example 1 6.7 355 58 356 1.12 / 1.08 13.4 award Comparative Example 2 6.2 360 68 377 1.03 / 1.07 10.9 under Comparative Example 3 6.4 350 61 345 1.15 / 1.11 18.2 award

From the results in Table 2, it was confirmed that the polyimide films of Examples 1 to 3 were excellent in mechanical properties such as elastic modulus, strength, and elongation, thermal properties such as glass transition temperature and MD/TD average CTE, adhesive properties, and film forming processability.

It was found that the polyimide films of Examples 1 to 3 had particularly high adhesion and low MD/TD average CTE, and thus had superior adhesion and MD/TD average CTE properties compared to the polyimide films of Comparative Examples 1 to 3.

That is, Examples 1 to 3 of the present invention all satisfied the following ranges: an adhesive strength of 1.2 kgf/cm or more, an average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) of less than 13 ppm/℃, a strength of 300 MPa or more, an elastic modulus of 5.0 GPa or more, an elongation of 50% or more, and a glass transition temperature of 340°C or more.

In addition, the polyimide films of Examples 1 to 3 of the present invention were all measured to have a film forming processability of “excellent”.

In comparison, the polyimide films of Comparative Examples 1 to 3 showed lower measured values in at least one of the adhesion and MD/TD average CTE characteristics compared to the polyimide films of the examples.

In addition, the polyimide film of Comparative Example 2 also showed a deterioration in film forming processability.

It can be seen that these effects of improving mechanical properties, thermal properties and adhesive properties are achieved by the components and composition ratios specified herein, and that the content of each component and the composition of the block play a decisive role.

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

Claims (14)

A polyimide comprising a diamine monomer and a dihydride monomer as polymerization units,
The above dianhydride monomers include benzophenonetetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA), and pyromellitic dianhydride (PMDA).
The above diamine monomers include 4,4′-oxydianiline (ODA), p-phenylenediamine (PPD) and 3,5-diaminobenzoic acid (DABA).
Based on 100 mol% of the total content of the above-mentioned dihydride monomer, the content of the benzophenone tetracarboxylic dianhydride is 15 mol% or more and 35 mol% or less, the content of the biphenyl tetracarboxylic dianhydride is 30 mol% or more and 50 mol% or less, and the content of the pyromellitic dianhydride is 30 mol% or more and 50 mol% or less.
Based on 100 mol% of the total content of the diamine monomer, the content of the oxydianiline is 35 mol% or more and 55 mol% or less, the content of the paraphenylene diamine is 35 mol% or more and 55 mol% or less, and the content of the 3,5-diaminobenzoic acid is 5 mol% or more and 15 mol% or less,
The adhesive strength is 1.2 kgf/cm or more,
The average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) is less than 13 ppm/℃, the strength is 300 MPa or more, the elastic modulus is 5.0 GPa or more, the elongation is 50% or more, and the glass transition temperature is 340°C or more.
Polyimide film. delete delete delete In the first paragraph,
The above polyimide is a copolymer including a block including the above oxydianiline and the above benzophenonetetracarboxylic dianhydride.
Polyimide film. In the first paragraph,
The above polyimide is a copolymer including a block including the above oxydianiline, the above benzophenonetetracarboxylic dianhydride and the above pyromellitic dianhydride.
Polyimide film. (a) a dianhydride monomer including benzophenonetetracarboxylic dianhydride (3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA), and pyromellitic dianhydride (PMDA),
A step of manufacturing a polyamic acid by polymerizing a diamine monomer including 4,4′-oxydianiline (ODA), p-phenylenediamine (PPD) and 3,5-diaminobenzoic acid (DABA) in an organic solvent; and
(b) a step of imidizing the polyamic acid;
Based on 100 mol% of the total content of the above-mentioned dihydride monomer, the content of the benzophenone tetracarboxylic dianhydride is 15 mol% or more and 35 mol% or less, the content of the biphenyl tetracarboxylic dianhydride is 30 mol% or more and 50 mol% or less, and the content of the pyromellitic dianhydride is 30 mol% or more and 50 mol% or less.
Based on 100 mol% of the total content of the diamine monomer, the content of the oxydianiline is 35 mol% or more and 55 mol% or less, the content of the paraphenylene diamine is 35 mol% or more and 55 mol% or less, and the content of the 3,5-diaminobenzoic acid is 5 mol% or more and 15 mol% or less,
The adhesive strength of the manufactured polyimide film is 1.2 kgf/cm or more, the average value of the coefficient of thermal expansion (CTE) in the machine direction (MD) and the coefficient of thermal expansion (CTE) in the transverse direction (TD) is less than 13 ppm/℃, the strength is 300 MPa or more, the elastic modulus is 5.0 GPa or more, the elongation is 50% or more, and the glass transition temperature is 340°C or more.
Method for manufacturing polyimide film. delete delete In Article 7,
The above polyimide is a copolymer including a block including the above oxydianiline and the above benzophenonetetracarboxylic dianhydride.
Method for manufacturing polyimide film. In Article 7,
The above polyamic acid is a copolymer including a block including the above oxydianiline, the above benzophenonetetracarboxylic dianhydride and the above pyromellitic dianhydride.
Method for manufacturing polyimide film. A multilayer film comprising a polyimide film according to any one of claims 1, 5, and 6 and a thermoplastic resin layer. A flexible metal foil laminate comprising a polyimide film according to any one of claims 1, 5, and 6 and an electrically conductive metal foil. An electronic component comprising a flexible metal laminate according to Article 13.