KR102141891B1 - Polyimide Film for Preparing Flexible Copper Clad Laminate And Flexible Copper Clad Laminate Comprising the Same - Google Patents

Abstract

The present invention provides an aromatic diamine monomer comprising at least three aromatic dianhydride monomers and a diamine having a carboxylic acid functional group and a diamine without a carboxylic acid functional group, together with paraphenylenediamine (p-PDA). Provided is a polyimide film prepared by imidizing a polyamic acid derived from polymerization of a monomer mixture included in a blending ratio, and a flexible copper-clad laminate comprising the same.

Description

Polyimide Film for Manufacturing Flexible Copper Clad Laminate and Flexible Copper Clad Laminate and Flexible Copper Clad Laminate Comprising the Same}

The present invention relates to a polyimide film for manufacturing a flexible copper-clad laminate and a flexible copper-clad laminate comprising the same.

Polyimide (PI) is a polymer material with thermal stability 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 has been in the spotlight as a high-functional polymer material, ranging from microelectronics to optical fields due to its excellent electrical properties such as insulation properties and low dielectric constant.

In the microelectronics field, for example, due to weight reduction and miniaturization of electronic products, high-density and flexible thin circuit boards have been actively developed, and thus polyimide, which has excellent heat resistance, low temperature resistance, and insulation properties and is easy to bend, has been developed. The trend is to use it as a protective film for thin circuit boards.

Such a thin circuit board has a structure in which a circuit including a metal foil is formed on a polyimide film, and such a thin circuit board is also referred to as a flexible metal foil laminate in a broad sense. In the narrow sense, is also referred to as Flexible Copper Clad Laminate (FCCL).

As a method for producing a flexible metal foil-clad laminate, for example, (i) casting or imposing a polyamic acid as a precursor of polyimide on a metal foil, followed by imidization, (ii) sputtering or plating. The metallization method of providing a metal layer directly on a polyimide film, and (iii) the lamination method of bonding a polyimide film and a metal foil through heat and pressure through a thermoplastic polyimide.

The double laminate method has an advantage in that the thickness range of the applicable metal foil is wider than the casting method, and the device cost is cheaper than the metallization method. As a device for laminating, a roll laminating device for continuously laminating while inputting a roll-like material, a double belt press device, or the like is used. Among the above, from the viewpoint of productivity, a heat roll lamination method using a heat roll lamination device can be more preferably used.

However, in the case of a laminate, since a thermoplastic resin is used to bond the polyimide film and the metal foil as described above, in order to express the heat-sealability of the thermoplastic resin, at least 300°C, in some cases, the glass transition of the polyimide film It is necessary to apply heat of 400° C. or higher close to or above the temperature (T _g ) to the polyimide film.

In general, it is known that the value of the storage elastic modulus of a viscoelastic body such as a polyimide film is significantly reduced compared to the value of the storage elastic modulus at room temperature in a temperature region exceeding the glass transition temperature.

That is, when performing lamination that requires high temperature, the storage elastic modulus of the polyimide film at high temperature may be significantly lowered, and under low storage elastic modulus, the polyimide film may become loose and the polyimide film may not exist in a flat form after lamination. This is high. In other words, in the case of a laminate, it can be said that the dimensional change of the polyimide film is relatively unstable.

Another thing to note is the case where the glass transition temperature of the polyimide film is significantly lower than the temperature at the time of lamination. Specifically, in this case, since the viscosity of the polyimide film is relatively high at a temperature at which lamination is performed, a relatively large dimensional change may be involved, and accordingly, after lamination, there is a fear that the appearance quality of the polyimide film is deteriorated. .

Therefore, there is a high need for a technology capable of significantly improving the fairness by solving the above problems.

The object of the present invention is to provide a polyimide film, and specifically, due to determining the type of the dianhydride monomer, the type of the diamine monomer and the blending ratio thereof, the desired glass transition temperature of the resulting polyimide film is determined. It has a high storage elastic modulus at high temperature, but also minimizes dimensional change by alleviating thermal stress.

Another object of the present invention is to provide a flexible copper-clad laminate having a relatively small dimensional change including a polyimide film that satisfies desired physical properties, and thereby excellent appearance quality.

The present invention to achieve the above object,

Pyromellitic dianhydride (PMDA),

Biphenyltetracarboxylic dianhydride (BPDA),

Benzophenonetetracarboxylic dianhydride (BTDA) and

At least three aromatic dianhydride monomers selected from the group consisting of oxydiphthalic anhydride (ODPA); And

Polyamic acid by polymerizing a monomer mixture comprising a diamine having a carboxylic acid functional group and an aromatic diamine monomer containing a diamine without a carboxylic acid functional group together with p-phenylenediamine (p-PDA) at a specific compounding ratio It provides a polyimide film prepared by imidizing the polyamic acid.

In the case of the polyimide film according to the present invention, while having a desired glass transition temperature, it has an excellent storage elastic modulus at a high temperature, and in addition, it is possible to minimize dimensional changes by relaxing thermal stress.

Hereinafter, embodiments of the present invention will be described in more detail in the order of "polyimide film", "method for producing polyimide film" and "soft copper-clad laminate" according to the present invention.

Prior to this, the terms or words used in the present specification and claims should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor appropriately explains the concept of terms in order to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Therefore, the configuration of the embodiments described herein 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 this application It should be understood that examples may exist.

In the present specification, a singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms “include”, “have” or “have” are intended to indicate the presence of implemented features, numbers, steps, elements, or combinations thereof, one or more other features or It should be understood that the existence or addition possibilities of numbers, steps, elements, or combinations thereof are not excluded in advance.

Polyimide film

The polyimide film according to the present invention,

Pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), benzophenonetetracarboxylic dianhydride (BTDA) and oxydiphthalic anhydride At least three aromatic dianhydride monomers selected from the group consisting of oxydiphthalic anhydride (ODPA); And

Aromatic diamine monomers including diamines having a carboxylic acid functional group and diamines without a carboxylic acid functional group, together with para-phenylenediamine (p-PDA); polyamic acid derived from polymerization of a monomer mixture comprising It is characterized by being produced by imidizing.

Such a polyimide film,

(a) has an inflection point of the storage modulus with respect to temperature in a range of more than 340°C;

(b) the glass transition temperature (T _g ) is 350°C or higher;

(c) The thermal expansion coefficient may be 7 ppm/°C or higher to 15 ppm/°C or lower.

In this regard, in the case of a polyimide film that satisfies all of the above three conditions, it has the effect of significantly suppressing the dimensional change when manufacturing the flexible copper-clad laminate using this.

The polyimide film having all three conditions is a novel polyimide film that has not been known so far, and the three conditions will be described in detail below.

<Inflection point of storage modulus>

The inflection point of the storage elastic modulus of the polyimide film according to the present invention may be preferably present in a range of more than 340°C to 370°C from the viewpoint of relaxation of thermal stress when bonding a metal foil by a lamination method.

Here, when the inflection point of the storage elastic modulus is lower than the above range, the polyimide film is excessively loosened during lamination, and there is a high possibility that external defects such as wool or wrinkles are formed on the surface of the polyimide film after lamination.

In addition, in the above case, after the heat is applied by the laminate, that is, even when the adhesion is completed, it may cause the dimensional change to be large as the softening of the core layer of the polyimide film is initiated by the residual amount of heat inherent in the polyimide film. .

Conversely, when it is higher than the above range, when laminating because the temperature at which the softening of the core layer starts is too high, the thermal stress is not sufficiently relieved, and this may also cause the dimensional change to deteriorate.

In more detail, it may be particularly preferable that the inflection point of the storage elastic modulus is within a range of 340°C or more and 360°C or less.

<glass transition temperature>

In the present invention, the glass transition temperature can be obtained from the storage elastic modulus and loss elastic modulus measured by a dynamic viscoelasticity measuring device (DMA), and in detail, the calculated loss elastic modulus divided by the storage elastic modulus is the top peak of tan δ. Can be calculated as the glass transition temperature.

In the polyimide film according to the present invention, the glass transition temperature (T _g ) may be 350°C or more, preferably 360°C or more to 380°C or less, and particularly preferably 360°C or more to 370°C or less.

When the glass transition temperature is lower than the above range, when laminating, since the viscosity of the polyimide film is relatively high, a large dimensional change may be involved. This is not preferable because it causes the appearance quality to be impaired.

On the other hand, when the glass transition temperature is higher than the above range, the temperature required to soften the core layer to a level sufficient to alleviate thermal distortion is too high, and the existing laminate device cannot sufficiently relieve the thermal stress and deteriorate the dimensional change. There is a possibility. That is, when it is out of the above range, the dimensional change may be deteriorated like the inflection point of the storage elastic modulus.

<Coefficient of thermal expansion>

In order to suppress the occurrence of thermal distortion during lamination with a metal foil, it is most ideal that the coefficient of thermal expansion of the polyimide film at 300°C to 350°C is the same as that of the metal foil. However, it is not practically easy to set the thermal expansion coefficient of the polyimide film to be the same as the metal foil, and in view of suppressing the occurrence of thermal distortion, the difference between the thermal expansion coefficient of the polyimide film and the thermal expansion coefficient of the metal foil is within ±10 ppm, detailed Preferably, it is within ±5 ppm.

However, when an adhesive layer having adhesiveness is formed between the polyimide film and the metal foil, the difference from the thermal expansion coefficient of the adhesive layer should also be considered.

Therefore, when the thermoplastic polyimide is used as the adhesive layer, the dimensional change can be minimized when the thermal expansion coefficient at 340°C of the polyimide film is 7 ppm/°C or more, and less, the dimensional change in the relationship with the metal foil and the adhesive layer Can appear excessively and cause bad appearance.

Also, in this case, the thermal expansion coefficient is preferably 15 ppm/° C. or less, and when it exceeds this, the degree of expansion in the MD and TD directions is excessive, which may also cause poor appearance. A more preferable range for this may be a thermal expansion coefficient of 8 ppm/°C or more to 13 ppm/°C or less, particularly preferably 8 ppm/°C or more to 12 ppm/°C or less.

As described above, the polyimide film according to the present invention can effectively suppress the dimensional change that occurs when manufacturing the flexible copper-clad laminate as all three conditions are satisfied.

As an embodiment of the present invention for a polyimide film having the above conditions, the type of the dianhydride monomer, the type of the diamine monomer, and the mixing ratio thereof are described in detail through the following non-limiting examples.

In one specific example, in the monomer mixture, the paraphenylenediamine (p-PDA) is 55 mol% or more to 80 mol% or less, based on the total number of moles of the diamine monomer,

The diamine having the carboxylic acid functional group is 5 mol% or more to 15 mol% or less based on the total number of moles of the diamine monomer,

The diamine without the carboxylic acid functional group may be 15 mol% or more and 40 mol% or less based on the total number of moles of the diamine monomer.

The paraphenylenediamine is preferable in that it has a rigid structure with no bending in the main chain between two NH ₂ groups, and the polyimide film finally obtained can be produced with non-thermoplasticity.

In addition, it is widely known that it is preferable to use a monomer having a rigid structure, that is, a monomer having high linearity, for the high elastic modulus of the polyimide film.

However, when a large amount of paraphenylenediamine having such a rigid structure is used, since the linear expansion coefficient of the polyimide film may be excessively reduced, in the present invention, as the diamine monomer, diamine having a carboxylic acid functional group and diamine not included It should be noted that it includes more.

When the use ratio of the paraphenylenediamine which is a diamine monomer having a rigid structure as described above exceeds the above range, the glass transition temperature of the resulting film becomes too high, the storage elastic modulus in the high temperature region hardly decreases, and the coefficient of linear expansion The danger of becoming too small can occur. Conversely, if it falls below this range, the opposite of the above-mentioned damage may occur. This similarly applies to the use ratio of diamine having a carboxylic acid functional group described below and diamine without a carboxylic acid functional group.

The diamine having a carboxylic acid functional group, 3,5-diaminobenzoic acid (DABA) and 4,4-diaminobiphenyl-3,3-tetracarboxylic acid (diaminobiphenyl-3,3-tetracarboxylic acid ; DATA) may be one or more selected from the group consisting of 3,5-diaminobenzoic acid (DABA), which may be advantageous in improving the mechanical properties of the polyimide film, specifically, the storage elastic modulus.

The diamine without the carboxylic acid functional group, oxydianiline (4,4'-oxydianiline; ODA), m-phenylenediamine (m-PDA), p-methylenediamine (p-MDA) And metamethylenediamine (m-methylenediamine; m-MDA), and may be oxydianiline (ODA).

The oxidianiline is a diamine monomer having a flexible structure having an ether group, and can impart an appropriate linear expansion coefficient to the polyimide film.

In one specific example, the monomer mixture is the aromatic dianhydride monomer, and includes a main component composed of the pyromellitic dianhydride (PMDA) and the biphenyltetracarboxylic dianhydride (BPDA),

The benzophenone tetracarboxylic dianhydride (BTDA) and the oxydiphthalan hydride (ODPA) may further include one subcomponent selected from the group.

That is, in the present invention, the aromatic dianhydride monomer includes a total of three dianhydride monomers, and is part of any one of pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA). It is characterized by being replaced by benzophenone tetracarboxylic dianhydride (BTDA) or oxydiphthalan hydride (ODPA).

Like diamine monomers, dianhydride monomers can be classified into dianhydrides having a flexible structure and dianhydrides having a rigid structure.

Here, in the case of a dianhydride having a relatively flexible structure, biphenyltetracarboxylic dianhydride (BPDA) may be exemplified, and benzophenone tetracarboxylic dianhydride (BTDA) and oxy which are selectively included Diphthalic anhydride (ODPA) can also be classified as a dianhydride having a flexible structure.

In the case of dianhydride having a relatively rigid structure, pyromellitic dianhydride (PMDA) can be exemplified. In other words, the main component comprising biphenyltetracarboxylic dianhydride (BPDA), a dianhydride having a flexible structure, and pyromellitic dianhydride (PMDA), a dianhydride having a rigid structure, is poly The storage elastic modulus and thermal expansion coefficient of the mid film can be induced by an appropriate line.

However, in order to achieve the above, the subcomponent is 5 mol% or more to 30 mol% or less based on the total number of moles of the aromatic dianhydride monomer, and the main component is based on the total number of moles of the aromatic dianhydride monomer. It may be 70 mol% or more to 95 mol% or less.

More specifically, the use ratio of the subcomponent is 10 mol% or more to 20 mol% or less, based on the total number of moles of the aromatic dianhydride monomer, and the main component is based on the total number of moles of the aromatic dianhydride monomer. As such, it may be 80 mol% or more to 90 mol% or less.

In addition, even in the main component, the molar ratio (=PMDA/BPDA) of the pyromellitic dianhydride (PMDA) to the biphenyltetracarboxylic dihydride (BPDA) is more than 0.45 to 1.25 or less, particularly the bi The molar ratio (=PMDA/BPDA) of the pyromellitic dianhydride (PMDA) to phenyltetracarboxylic dianhydride (BPDA) may be preferably 0.6 or more and 0.8 or less.

For reference, in the present invention, the main component and the sub-component are only for clearly distinguishing a monomer that occupies a relatively more mole% and a monomer that occupies a relatively small mole%, and the concept of dividing into a monomer that leads the reaction and a monomer that does not. Is not.

Meanwhile, in one specific example, the polyamic acid may include two or more kinds of partial chains of different molecular structures derived from a sequential polymerization reaction in the polymer chain. This will be described in more detail in the production method of the polyimide film described below.

Manufacturing method of polyimide film

The polyimide film of the present invention is obtained from polyamic acid, which is a precursor of polyimide.

The polyamic acid according to the present invention dissolves the monomer mixture in which the aromatic diamine monomer and the aromatic dianhydride monomer are combined in a substantially equimolar amount in an organic solvent, and the obtained polyamic acid organic solvent solution is mixed with the aromatic dianhydride monomer under controlled temperature conditions. It is prepared by stirring until the polymerization of the aromatic diamine monomer is completed.

The polyamic acid is usually obtained in a concentration of 7 to 25% by weight, preferably 10 to 20% by weight, of solid content. For concentrations in this range, the polyamic acid obtains a suitable molecular weight and solution viscosity.

The solvent for producing the polyamic acid is not particularly limited, and any solvent can be used as long as it is a solvent for dissolving the polyamic acid, but it is preferably an amide solvent. Specifically, the solvent may be an aprotic polar solvent, for example, N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), N -Methyl-pyrrolidone (NMP), gamma brotirolactone (GBL), digrime (Diglyme) may be one or more selected from the group consisting of, but is not limited to, alone or in combination of two or more, if necessary Can be used. In one example, N,N-dimethylformamide and N,N-dimethylacetamide are particularly preferably used as the solvent.

The polyimide film of the present invention can control various physical properties by controlling the order of addition of the monomer, as well as the composition of the aromatic diamine monomer and the aromatic dianhydride monomer as raw material monomers.

In one specific example, the method for manufacturing the polyimide film is specifically,

Preparing a first polyamic acid by polymerizing a monomer mixture containing the aromatic diamine monomer in an excessive amount compared to the aromatic dianhydride monomer;

After the polymerization is completed, an aromatic diamine monomer and an aromatic dianhydride monomer are additionally added to the mixture of the residual monomer and the polyamic acid to prepare a monomer mixture having a different monomer composition from the monomer mixture of the previous step, and polymerized to prepare in the previous step. Extending a subchain having a different composition at the end of the polyamic acid;

After the polymerization is completed, a mixture of the residual monomer and the polyamic acid is further mixed with an aromatic dianhydride monomer to prepare a final monomer mixture in which the aromatic dianhydride monomer and the aromatic diamine monomer are substantially equimolar, and polymerized to finalize the mixture. Preparing a polyamic acid; And

After forming the final polyamic acid on a support, imidization may include a step of obtaining a polyimide film, and the monomer mixture may include the amide-based solvent.

In this manufacturing method, in order to obtain desired properties, the type of the sub-chain and the number of sub-chain extensions can be changed, and specifically, the step of extending the sub-chain can be repeated from 1 to 4 times.

That is, the polymerization and the monomer input are alternating, but a monomer composition having a different composition for each polymerization is polymerized to induce formation of a partial chain having a different monomer composition for each polymerization, and the formation of the partial chain can be sequentially controlled.

Accordingly, the polyamic acid in which polymerization is finally completed may include two or more subchains having different monomer compositions in its polymer chain.

In the step of preparing the final polyamic acid, the dianhydride monomer further mixed with the first polyamic acid may be pyromellitic dianhydride (PMDA).

On the other hand, in the "manufacturing method of the polyimide film", a filler may be added for the purpose of improving various properties of the film, such as sliding property, thermal conductivity, conductivity, corona resistance, and loop hardness. Although not preferred, preferred examples include silica, 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 the filler to be added. In general, the average particle diameter is 0.05 µm to 100 µm, preferably 0.1 µm to 75 µm, more preferably 0.1 µm to 50 µm, particularly preferably 0.1 µm to 25 µm.

When the particle diameter is less than this range, a modification effect is unlikely to appear, and when it exceeds this range, surface properties may be greatly impaired, or mechanical properties may be greatly deteriorated.

In addition, the addition amount of the filler is not particularly limited, and may be determined by film characteristics to be modified, particle size of the filler, and the like. In general, the amount of the filler added is from 0.01 to 100 parts by weight, preferably from 0.01 to 90 parts by weight, more preferably from 0.02 to 80 parts by weight, based on 100 parts by weight of polyimide.

If the amount of the filler added is less than this range, the modification effect by the filler is unlikely to appear, and if it exceeds this range, there is a possibility that the mechanical properties of the film are significantly impaired. The method for adding the filler is not particularly limited, and any known method may be used.

As a method for producing a polyimide film by imidizing the polyamic acid prepared as described above, a conventionally known method can be used. Specifically, a thermal imidization method and a chemical imidization method are mentioned.

The thermal imidization method is a method in which an imidization reaction proceeds only by heating without causing dehydration pulmonary agents to act.

On the other hand, the chemical imidization method is a method of promoting imidation by activating a chemical conversion agent and/or an imidation catalyst on the polyamic acid.

"Chemical converting agent" means a dehydrating cyclization agent for polyamic acid, for example, aliphatic acid anhydride, aromatic acid anhydride, N,N'-dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower fatty acid anhydride, Arylphosphonic acid dihalides, and thionyl halides, or mixtures of two or more of these. Among these, aliphatic acid anhydrides, such as acetic anhydride, propionic anhydride, and lactic anhydride, or mixtures of two or more thereof, can be preferably used from the viewpoint of ease of availability and cost.

In addition, "imidation catalyst" means a component having an effect of promoting dehydration ring-closing action to polyamic acid, and for example, aliphatic tertiary amine, aromatic tertiary amine, and heterocyclic tertiary amine are used. Among them, those selected from heterocyclic tertiary amines are particularly preferably used from the viewpoint of reactivity as a catalyst. Specifically, quinoline, isoquinoline, β-picoline, pyridine and the like are preferably used.

Although the film can be produced by using either the thermal imidization method or the chemical imidization method, the chemical imidization method tends to be easy to obtain a polyimide film having various properties that are preferably used in the present invention.

In the case of using a chemical imidization method in the imidization step, the imidization step applies a composition for forming a film containing the polyamic acid on a support, heats it on a support to form a gel film, and peels the gel film from the support It is preferable to further include a process of heating the gel film and imidizing and drying the remaining amic acid (hereinafter, also referred to as a "firing process").

Each process described above will be described in detail below.

In order to produce a gel film, a chemical conversion agent and/or an imidization catalyst are first mixed in a polyamic acid at a low temperature to obtain a composition for film formation.

The chemical conversion agent and the imidation catalyst are not particularly limited, and the above-exemplified compounds can be selected and used. Further, in the gel film production process, a composition for forming a film may be obtained by mixing in a polyamic acid using a curing agent containing a chemical conversion agent and an imidization catalyst.

It is preferable that the addition amount of the chemical converting agent is in the range of 0.5 mol to 5 mol with respect to 1 mol of the amide acid unit in the polyamic acid, and more preferably in the range of 1.0 mol to 4 mol. Moreover, it is preferable that the addition amount of the imidation catalyst is in the range of 0.05 mol to 2 mol with respect to 1 mol of the amic acid unit in the polyamic acid, and it is particularly preferable to be in the range of 0.2 mol to 1 mol.

When the chemical converting agent and the imidation catalyst are less than the above range, chemical imidation may be insufficient, and may break during firing or the mechanical strength may be lowered. Further, if these amounts exceed the above range, imidization proceeds rapidly, and casting in a film form may be difficult, which is not preferable.

On the other hand, next, the film-forming composition is cast in a film form on a support such as a glass plate, aluminum foil, endless stainless belt, or stainless drum. Thereafter, the composition for film formation on the support is heated in a temperature range of 60°C to 200°C, preferably 80°C to 180°C. In this way, the chemical converting agent and the imidization catalyst are activated, and partially cured and/or dried occurs, thereby forming a gel film. Then, it peels off from a support body, and a gel film is obtained.

The gel film is in the middle stage of curing from polyamic acid to polyimide and has self-supporting properties. The volatile content of the gel film is preferably in the range of 5% to 500% by weight, more preferably in the range of 5% to 200% by weight, and particularly preferably in the range of 5% to 150% by weight. . By using a gel film having a volatile content within this range, defects such as film rupture occurring in the firing step, color unevenness of the film due to dry stains, and characteristic fluctuations can be avoided.

Flexible copper-clad laminate

The present invention provides a flexible copper-clad laminate comprising the above-described polyimide film and copper foil. The present invention also provides an electronic device including the flexible copper-clad laminate. Here, the electronic device is not particularly limited as long as it has a microcircuit and is an electronic device that can include a flexible copper-clad laminate as a circuit board.

In the flexible copper-clad laminate according to the present invention, a copper foil is laminated on one surface of the polyimide film, or

An adhesive layer containing a thermoplastic polyimide is added to one surface of the polyimide film, and a copper foil may be laminated in a state attached to the adhesive layer.

In the present invention, the thickness of the copper foil is not particularly limited, and may be a thickness capable of exerting a sufficient function depending on the use.

As described above, the present invention, due to the combination of specific dianhydride monomers, diamine monomers and specific mixing ratios thereof, has a desired glass transition temperature, and has a high storage elastic modulus at high temperature, in addition to thermal stress It is possible to provide a polyimide film capable of minimizing dimensional changes by alleviating.

The present invention can also provide a flexible copper-clad laminate having excellent appearance quality, including the polyimide film as described above.

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

<Example 1>

DABA, ODA, and BPDA were added to DMF in a state in which the reaction system was maintained at 10°C in a molar ratio shown in Table 1 below, and stirred for 1 hour to prepare a first polyamic acid. After visually confirming the dissolved substance, p-PDA was added at a molar ratio shown in Table 1, and after dissolving, BTDA was added at a molar ratio shown in Table 1, and stirred for 1 hour to have different compositions at the ends of the first polyamic acid. The partial chain was extended.

Subsequently, PMDA was added in the molar ratio shown in PMDA in Table 1 to make the aromatic dianhydride monomer and the aromatic diamine monomer substantially equimolar, and stirred for 1 hour to reach a viscosity of 1500 poise. At the time point, polymerization was terminated to prepare a final polyamic acid.

To the final polyamic acid thus obtained, an imidization accelerator comprising acetic anhydride/isoquinoline/DMF (weight ratio 46&/13%/41%) was added in 50 parts by weight based on 100 parts by weight of polyamic acid, and the resulting mixture was added to a stainless steel plate. After application, a 400 μm gap was cast using a doctor blade, and then dried in a hot air at 120° C. for 4 minutes to prepare a gel film.

The gel film thus prepared was removed from the stainless steel plate, fixed with a frame pin, and then heat-treated at 400°C for 7 minutes for a frame with a fixed gel film to remove the film, thereby obtaining a polyimide film having an average thickness of 15 μm.

<Example 2>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 1, except that the molar ratio of PMDA and BTDA was changed as shown in Table 1.

<Example 3>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 1, except that the molar ratio of PMDA and BTDA was changed as shown in Table 1.

<Example 4>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 1, except that the composition was changed as shown in Table 1 using ODPA instead of BTDA.

<Example 5>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 4, except that the molar ratio of PMDA and ODPA was changed as shown in Table 1.

<Example 6>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 4, except that the molar ratio of PMDA and ODPA was changed as shown in Table 1.

<Comparative Example 1>

DABA, ODA, and BPDA were added to DMF in a molar ratio shown in Table 1 in the state that the reaction system was maintained at 10° C., and the mixture was stirred for 1 hour. After confirming the dissolved matter, p-PDA and PMDA were added at a molar ratio shown in Table 1 and dissolved, followed by stirring at 20°C for 1 hour to terminate polymerization at the point when the viscosity reached 1500 poise. Polyamic acid was prepared.

The imidization accelerator containing acetic anhydride/isoquinoline/DMF (weight ratio 46&/13%/41%) to the polyamic acid thus obtained was added in 50 parts by weight based on 100 parts by weight of polyamic acid, and the obtained mixture was applied to a stainless steel plate After casting using a 400 µm gap using a doctor blade, dried in a hot air at 120° C. for 4 minutes to prepare a gel film.

The gel film thus prepared was removed from the stainless steel plate, fixed with a frame pin, and then heat-treated at 400°C for 7 minutes for a frame with a fixed gel film to remove the film, thereby obtaining a polyimide film having an average thickness of 15 μm.

<Comparative Example 2>

ODA, DABA, p-PDA and BPDA were added to DMF at a molar ratio shown in Table 1 in the state where the reaction system was maintained at 10° C., and stirring was performed. After confirming that the dissolved substance was visually observed, polymerization was terminated when stirring was performed at 20°C for 1 hour to reach a viscosity of 1500 poise.

The imidization accelerator containing acetic anhydride/isoquinoline/DMF (weight ratio 46&/13%/41%) to the polyamic acid thus obtained was added in 50 parts by weight based on 100 parts by weight of polyamic acid, and the obtained mixture was applied to a stainless steel plate After casting using a 400 µm gap using a doctor blade, and dried for 4 minutes in a hot air in an oven at 120° C. to prepare a gel film.

The gel film thus prepared was removed from the stainless steel plate, fixed with a frame pin, and then heat-treated at 400°C for 7 minutes for a frame with a fixed gel film to remove the film, thereby obtaining a polyimide film having an average thickness of 15 μm.

<Comparative Example 3>

ODA, p-PDA and BPDA were added to DMF at a molar ratio shown in Table 1 in the state that the reaction system was maintained at 25°C, and stirring was performed. After confirming that the dissolved substance was visually observed, polymerization was terminated when stirring was performed at 20°C for 1 hour to reach a viscosity of 1500 poise.

The imidization accelerator containing acetic anhydride/isoquinoline/DMF (weight ratio 46&/13%/41%) to the polyamic acid thus obtained was added in 50 parts by weight based on 100 parts by weight of polyamic acid, and the obtained mixture was applied to a stainless steel plate After casting using a 400 µm gap using a doctor blade, and dried for 4 minutes in a hot air in an oven at 120° C. to prepare a gel film.

The gel film thus prepared was removed from the stainless steel plate, fixed with a frame pin, and then heat-treated at 400°C for 7 minutes for a frame with a fixed gel film to remove the film, thereby obtaining a polyimide film having an average thickness of 15 μm.

<Comparative Example 4>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 1, except that the molar ratios of PMDA, BPDA, and BTDA were changed as shown in Table 1.

<Comparative Example 5>

A polyimide film having a thickness of 15 μm was obtained in the same manner as in Example 4, except that the molar ratios of PMDA, BPDA, and ODPA were changed as shown in Table 1.

Dianhydride monomer (mol%) Diamine monomer (mol%) PMDA BPDA BTDA ODPA p-PDA ODA DABA Example 1 30 50 20 0 65 20 15 Example 2 35 50 15 0 65 20 15 Example 3 40 50 10 0 65 20 15 Example 4 30 50 0 20 65 20 15 Example 5 35 50 0 15 65 20 15 Example 6 40 50 0 10 65 20 15 Comparative Example 1 50 50 0 0 65 20 15 Comparative Example 2 0 100 0 0 65 20 15 Comparative Example 3 0 100 0 0 65 35 0 Comparative Example 4 20 40 40 0 65 20 15 Comparative Example 5 20 40 0 40 65 20 15

<Experimental Example 1>

For the polyimide films prepared in Examples 1 to 6 and Comparative Examples 1 to 5, respectively, the storage modulus inflection point and the glass transition temperature (T _g ) value were measured using DMA and the results are shown in Table 2 below. It is shown in.

In addition, the thermal expansion coefficient of each polyimide film was measured using TMA, and the results are also shown in Table 2.

Glass transition temperature
(℃) Inflection point
(℃) Coefficient of thermal expansion (ppm/℃) Example 1 369 355 11 Example 2 367 352 10 Example 3 366 350 9 Example 4 365 354 10 Example 5 365 353 9 Example 6 363 353 8 Comparative Example 1 369 355 6 Comparative Example 2 323 311 11 Comparative Example 3 290 278 14 Comparative Example 4 352 336 20 Comparative Example 5 346 331 18

Referring to Table 2, in the case of the polyimide film according to Examples 1 to 6, it can be seen that all of the following conditions are satisfied.

On the other hand, in Comparative Example 1 and Comparative Example 5, it can be seen that at least one of the following conditions is not satisfied.

(a) The inflection point of the storage modulus with respect to temperature exists in the range of more than 340°C

(b) The glass transition temperature (T _g ) is more than 350℃

(c) Thermal expansion coefficient of 7 ppm/℃ or higher to 15 ppm/℃ or lower

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

Claims (13)

Pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), benzophenonetetracarboxylic dianhydride (BTDA) and oxydiphthalic anhydride At least three aromatic dianhydride monomers selected from the group consisting of oxydiphthalic anhydride (ODPA), comprising a main component composed of the PMDA and the BPDA, and at least one subcomponent selected from the BTDA and the ODPA Aromatic dianhydride monomers further comprising; And
A polyamic acid derived from polymerization of a monomer mixture comprising a diamine having a carboxylic acid functional group and an aromatic diamine monomer containing a diamine without a carboxylic acid functional group together with p-phenylenediamine (p-PDA) It is produced by imidization,
The subcomponent is 10 mol% or more to 20 mol% or less based on the total number of moles of the aromatic dianhydride monomer, and the main component is 80 mol% or more to 90 mol% or less based on the total number of moles of the aromatic dianhydride monomer. And
The thermal expansion coefficient at 300°C to 350°C is 7 ppm/°C or more to 15 ppm/°C or less,
The polyimide film, wherein the molar ratio of the PMDA to the BPDA (= PMDA/BPDA) is 0.6 to 0.8. delete delete According to claim 1,
In the monomer mixture, the content of the p-PDA is 55 mol% or more to 80 mol% or less, based on the total number of moles of the aromatic diamine monomer,
The content of the diamine having a carboxylic acid functional group is 5 mol% or more to 15 mol% or less, based on the total number of moles of the aromatic diamine monomer,
The content of the diamine without the carboxylic acid functional group is 15 mol% or more and 40 mol% or less, based on the total number of moles of the aromatic diamine monomer. According to claim 1,
The diamine having a carboxylic acid functional group, 3,5-diaminobenzoic acid (DABA) and 4,4-diaminobiphenyl-3,3-tetracarboxylic acid (diaminobiphenyl-3,3-tetracarboxylic acid ; DATA) polyimide film comprising at least one selected from the group consisting of. The method of claim 5,
The diamine having the carboxylic acid functional group is DABA, a polyimide film. According to claim 1,
The diamine without the carboxylic acid functional group, oxydianiline (4,4'-oxydianiline; ODA), m-phenylenediamine (m-PDA), p-methylenediamine (p-MDA) And metamethylenediamine (m-methylenediamine; m-MDA). The method of claim 7,
The polyamine film, wherein the diamine without the carboxylic acid functional group is ODA. The polyimide film of claim 1, wherein the polyimide film satisfies both the following conditions (a) and (b):
(a) has an inflection point of the storage modulus with respect to temperature in a range of more than 340°C;
(b) The glass transition temperature (T _g ) is 350°C or higher. According to claim 1,
The polyimide film is a polyimide film produced by imidizing a polyamic acid containing two or more partial chains having different monomer compositions derived from sequential polymerization reactions in a polymer chain. A flexible copper-clad laminate comprising the polyimide film and copper foil according to claim 1. The method of claim 11,
Copper foil is laminated on one surface of the polyimide film, or
An adhesive layer containing a thermoplastic polyimide is added to one surface of the polyimide film, and the copper foil is laminated in a state where it is attached to the adhesive layer. An electronic device comprising the flexible copper-clad laminate according to claim 11.