TWI705092B - Polyimide film and preparation method thereof for preparing flexible copper clad laminate, and flexible copper clad laminate and electronic device comprising the same - Google Patents

Abstract

The present invention provides a polyimide prepared by imidizing polyimide The film and its preparation method, the flexible copper foil laminated board comprising the polyimide film and the electronic device comprising the laminated board, the above-mentioned polyamide is polymerized to include at least three aromatic dianhydride monomers in a specific mixing ratio It is composed of a monomer mixture of aromatic diamine monomers including diamine with carboxylic acid functional group and diamine without carboxylic acid functional group together with p-phenylenediamine.

Description

Polyimide film for manufacturing soft copper foil laminated board and preparation method thereof Method, flexible copper foil laminated board containing the polyimide film and electronic device containing the laminated board

The present invention relates to a polyimide film for manufacturing a flexible copper foil laminated board and a flexible copper foil laminated board including the polyimide film.

Polyimide (PI), as a thermally stable polymer material based on a strong aromatic main chain, has excellent mechanical strength, chemical resistance, and weather resistance based on the chemical stability of the amide ring Resistance and heat resistance.

Not only that, because of its excellent electrical properties such as insulation properties and low dielectric constant, it is favored as a highly functional polymer material in the field of microelectronics and even in the optical field.

Taking the field of microelectronics as an example, due to the light weight and miniaturization of electronic products, a thin circuit board with a high degree of integration and flexibility is being actively developed. Therefore, the trend is as follows: it will have very excellent heat resistance and low temperature resistance And insulation properties, and easy The curved polyimide is used as a protective film for thin circuit boards.

This kind of thin circuit board usually has a structure in which a circuit including a metal foil is formed on a polyimide film. In a broad sense, this kind of thin circuit board is also called a flexible metal foil laminate. As an example, it will be thinner. When the copper plate is used as metal foil, it is also called Flexible Copper Clad Laminate (FCCL) in a narrow sense.

As a manufacturing method of a flexible metal foil laminated board, for example: (i) Casting or coating a polyamide acid as a precursor of polyimide on a metal foil and then carrying out imidization Extension method; (ii) a metal spraying method in which a metal layer is directly provided on the polyimide film by sputtering or plating; and (iii) a thermoplastic polyimide is used to make the polyimide using heat and pressure A lamination method in which imine film and metal foil are joined.

Among them, the lamination method has the advantages that the applicable metal foil has a larger thickness range than the casting method and the equipment cost is lower than that of the metal spray method. As a device for performing lamination, a roll lamination device that continuously performs lamination by feeding a roll-shaped material, or a double belt press device, or the like. Among them, from the viewpoint of productivity, a hot roll lamination method using a hot roll lamination device can be more preferably used.

However, as described above, lamination uses a thermoplastic resin when adhering the polyimide film to the metal foil. Therefore, in order to exhibit the thermal fusion property of the above-mentioned thermoplastic resin, the polyimide film needs to be applied to the polyimide film at 300°C or higher, depending on the situation. It is necessary to apply heat close to the glass transition temperature (T _g ) of the polyimide film or above the glass transition temperature, that is, above 400°C.

Generally, it is known that the value of the storage modulus of a viscoelastic body such as a polyimide film is significantly lower than the value of the storage modulus at room temperature in a temperature region exceeding the glass transition temperature.

That is, when performing lamination that requires high temperature, the polyimide film under high temperature The storage modulus will be significantly lower. Under low storage modulus, the polyimide film will relax, so that the polyimide film may not exist in a flat form after the lamination is completed. In other words, during lamination, the dimensional change of the polyimide film can be said to be relatively unstable.

It should also be noted that the glass transition temperature of the polyimide film is significantly lower than the temperature when the lamination is performed. Specifically, in the above situation, the viscosity of the polyimide film is relatively high at the temperature at which the lamination is performed, and therefore relatively large dimensional changes occur, so there is a problem in the polyimide film after lamination. The appearance quality of the imine film may decrease.

Therefore, there is an urgent need for a technology that can solve the above problems and greatly improve the processability.

The purpose of the present invention is to provide a polyimide film. Specifically, by determining the type of dianhydride monomer, the type of diamine monomer and the blending ratio, the polyimide film as the product has the desired Glass transition temperature and high storage modulus at high temperature. In addition, it relaxes thermal stress and minimizes dimensional changes.

Another object of the present invention is to provide a flexible copper foil laminated board that includes a polyimide film that satisfies desired physical properties, has relatively small dimensional changes, and therefore has excellent appearance quality.

In order to achieve the above-mentioned object, the present invention provides a polyimide film, which is prepared by the following method: polymerizing with a specific mixing ratio, including selected from pyromellitic dianhydride (PMDA), biphenyl tetracarboxylic acid Carboxylic dianhydride (biphenyltetracarboxylic dianhydride, BPDA), benzophenone tetracarboxylic acid two At least three aromatic dianhydride monomers in the group consisting of benzophenonetetracarboxylic dianhydride (BTDA) and oxydiphthalic anhydride (ODPA); and together with p-phenylenediamine (p-PDA) ) A monomer mixture including a diamine having a carboxylic acid functional group and an aromatic diamine monomer that does not include a diamine having a carboxylic acid functional group together to prepare a polyamide acid, and the above polyamide acid is imidized .

The polyimide film of the present invention has a desired glass transition temperature and an excellent storage modulus at high temperatures. In addition, it can relax thermal stress and minimize dimensional changes.

Hereinafter, the embodiments of the invention will be described in more detail in the order of the "polyimide film", "the production method of the polyimide film", and the "soft copper foil laminated board" of the present invention.

Prior to this, the use in this specification and the scope of the invention application Words or words should not be interpreted limitedly as ordinary meanings or meanings in a dictionary. In order for the inventor to explain his own invention in the best way, he should only be interpreted as conforming to the present invention based on the principle that the concept of the terms can be appropriately defined The meaning and concept of the technical thoughts.

Therefore, the configuration of the embodiment described in this specification is only the best embodiment of the present invention, and does not represent all the technical ideas of the present invention. Therefore, it should be understood that there may be alternatives from the perspective of this application. Various equivalents and modifications of the above embodiments.

In this specification, as long as other meanings are not clearly expressed in the text, the expression of the singular number includes the expression of the plural number. In this specification, it should be understood that the terms "include", "have" or "have" indicate the existence of implemented features, numbers, steps, constituent elements, or combinations thereof, and do not preclude one or more other features, numbers, The existence or additional possibilities of steps, constituent elements, or combinations thereof.

Polyimide film

The polyimide film of the present invention is characterized in that it is prepared by imidizing polyimide, and the polyimide is polymerized and includes selected from pyromellitic dianhydride (PMDA), combined At least three of the group consisting of biphenyltetracarboxylic dianhydride (BPDA), benzophenonetetracarboxylic dianhydride (BTDA) and oxydiphthalic anhydride (ODPA) Aromatic dianhydride monomers; and aromatic diamine monomers including diamines with carboxylic acid functional groups and diamines that do not include carboxylic acid functional groups together with p-phenylenediamine (p-PDA) A mixture of monomers.

Such polyimide film (a) can have a storage modulus reflex point with respect to temperature in the range of 340°C or higher; (b) the glass transition temperature (T _g ) is 350°C or higher; (c) thermal expansion The coefficient is above 7ppm/℃ and below 15ppm/℃.

In connection with this, when a polyimide film that satisfies the above three conditions is used to produce a flexible copper foil laminated board, it has an effect of significantly suppressing dimensional changes.

The polyimide film having the above three conditions is a novel polyimide film that has not been disclosed so far. Hereinafter, the above three conditions will be described in detail.

<Recurve point of storage modulus>

From the viewpoint of alleviating the thermal stress at the time of joining metal foils by the lamination method, it is preferable that the inflection point of the storage modulus of the polyimide film of the present invention exists in the range of 340°C or higher to 370°C.

Here, when the inflection point of the storage modulus is lower than the above range, the The polyimide film becomes too loose during lamination, and there is a high possibility that appearance defects such as waves or wrinkles are formed on the surface of the polyimide film after the lamination is completed.

In addition, the above situation will become the reason for the following situation: after the heat is applied by lamination, that is, at the point of the end, the core layer of the polyimide film starts to soften due to the residual heat of the polyimide film , So that the size change becomes larger.

On the contrary, when the temperature is higher than the above range, the temperature at which the core layer starts to soften is too high, so when laminating is performed, the thermal stress relaxation is insufficient, which may cause deterioration in dimensional changes.

In more detail, it is particularly preferable that the inflection point of the storage modulus exists in the range of 340°C or higher and 360°C or lower.

<Glass transition temperature>

In the present invention, the glass transition temperature can be obtained from the storage modulus and loss elastic modulus measured by a dynamic viscoelasticity measuring device (Dynamic Thermomechanical Analyzer (DMA)). In detail, The value obtained by dividing the calculated loss elastic modulus by the storage modulus, that is, the top peak of tan δ is calculated as the glass transition temperature.

In the polyimide film of the present invention, the glass transition temperature (T _g ) may be 350° C. or higher, preferably 360° C. or higher and 380° C. or lower, particularly preferably 360° C. or higher and 370° C. or lower.

When the glass transition temperature is lower than the above range, the viscosity of the polyimide film is relatively high during lamination, and therefore, a large dimensional change occurs. It is the reason that hinders the appearance quality, so it is not good.

Conversely, when the glass transition temperature is higher than the above-mentioned range, the temperature required to soften the core layer to a sufficient level becomes excessive when the thermal strain is relaxed. Because it is high, the existing laminating device cannot sufficiently relax the thermal stress, and there is a possibility of deterioration due to dimensional change. That is, when it is out of the above range, it will cause dimensional change and deterioration similar to the inflection point of the storage modulus.

<Coefficient of Thermal Expansion>

When laminating with a metal foil, in order to suppress the occurrence of thermal strain, it is most desirable that the thermal expansion coefficient of the polyimide film at 300°C to 350°C is the same as that of the metal foil. However, it is not easy to set the thermal expansion coefficient of the polyimide film in the same way as the metal foil. In terms of suppressing thermal strain, the difference between the thermal expansion coefficient of the polyimide film and that of the metal foil is better. It is within ±10ppm, specifically within ±5ppm.

However, when forming an adhesive layer with adhesive properties between the polyimide film and the metal foil, it is also necessary to consider the difference in thermal expansion coefficient from the above adhesive layer.

Therefore, when a thermoplastic polyimide is used as an adhesive layer, when the thermal expansion coefficient at 340°C of the polyimide film is 7 ppm/°C or more, the dimensional change can be minimized to less than 7 ppm/°C. At °C, excessive dimensional changes are shown in the relationship between the metal foil and the adhesive layer, which may cause poor appearance.

In addition, in this case, the thermal expansion coefficient is preferably 15ppm/℃ or less. When it exceeds 15ppm/℃, the degree of expansion in the machine direction (MD) and transverse direction (TD) is too large, which will also cause bad apperance. In this regard, a more preferable range may be a coefficient of thermal expansion of 8 ppm/°C or higher and 13 ppm/°C or lower, particularly preferably 8 ppm/°C or higher and 12 ppm/°C or lower.

As described above, the polyimide film of the present invention satisfies the above three conditions, and therefore can effectively suppress the dimensional change that occurs when the flexible copper foil laminate is manufactured.

As a specific example of the present invention of the polyimide film having the above conditions, The types of dianhydride monomers, the types of diamine monomers, and their blending ratios are described in detail from the following non-limiting examples.

In a specific example, the p-phenylenediamine (p-PDA) in the monomer mixture can be 55 mol% or more and 80 mol% or less based on the overall mol number of the diamine monomer, having The diamine of the above-mentioned carboxylic acid functional group is based on the overall molar number of the above-mentioned diamine monomer and is 5 mol% or more and 15 mol% or less. The overall molar number of the body is 15 mol% or more and 40 mol% or less as a reference.

The above-mentioned p-phenylenediamine has a strong structure with no bendability in the main chain between the two NH ₂ groups, and is preferable in that the finally obtained polyimide film can be prepared into a non-thermoplasticity.

In addition, it is known that in order to achieve a high elastic modulus of a polyimide film, it is preferable to use a monomer with a strong structure, that is, a monomer with high linearity.

However, when a large amount of p-phenylenediamine with such a strong structure is used, the coefficient of linear expansion of the polyimide film will be excessively decreased. Therefore, in the present invention, it should be noted that it also includes those with carboxylic acid functional groups. Aspects of diamines and diamines that do not include carboxylic acid functional groups as diamine monomers.

If the use ratio of p-phenylenediamine as a diamine monomer having a strong structure as described above is greater than the above range, the following disadvantages will occur: the glass transition temperature of the obtained film becomes too high, and the storage mold in the high temperature region The number hardly drops, and the coefficient of linear expansion becomes too small. Conversely, if it falls below the above range, the opposite will occur. This situation is similarly applicable to the usage ratio of the diamine having a carboxylic acid functional group and the diamine not including the carboxylic acid functional group described below.

The diamine having the above carboxylic acid functional group may be selected from 3,5-diaminobenzoic acid (DABA) and 4,4-diaminobiphenyl-3,3-tetracarboxylic acid (diaminobiphenyl-3 ,3-tetracarboxylic acid, DATA) is composed of more than one group. In detail, it can be a 3,5-diamine group that can help improve the mechanical properties of the polyimide film, specifically the storage modulus. Benzoic acid (DABA).

The diamine that does not include the aforementioned carboxylic acid functional group can be selected from oxydiphenylamine (4,4'-oxydianiline, ODA), m-phenylenediamine (m-phenylenediamine, m-PDA), p-methylene diamine ( One or more of the group consisting of p-methylenediamine (p-MDA) and m-methylenediamine (m-MDA), in detail, may be oxydiphenylamine (ODA).

The above-mentioned oxydiphenylamine is a diamine monomer having a flexible structure with an ether group, and can impart an appropriate linear expansion coefficient to a polyimide film.

In a specific example, the monomer mixture may include the main components of the pyromellitic dianhydride (PMDA) and the biphenyl tetracarboxylic dianhydride (BPDA) as the aromatic dianhydride monomers, and further include optional One of the side components from the above benzophenone tetracarboxylic dianhydride (BTDA) and the above oxydiphthalic anhydride (ODPA).

That is, the present invention has the following characteristics: the aromatic dianhydride monomer includes a total of three dianhydride monomers, and a part of any one of pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA) is composed of As a side component, benzophenone tetracarboxylic dianhydride (BTDA) or oxydiphthalic anhydride (ODPA) is substituted.

Like diamine monomers, dianhydride monomers can also be divided into dianhydrides having a soft structure and dianhydrides having a strong structure.

Here, the dianhydrides having a relatively soft structure include biphenyl tetracarboxylic dianhydride (BPDA), optionally including benzophenone tetracarboxylic dianhydride (BTDA) and Oxydiphthalic anhydride (ODPA) can also be classified as a dianhydride with a soft structure.

As the dianhydride having a relatively strong structure, pyromellitic dianhydride (PMDA) can be cited. That is, the main components including biphenyltetracarboxylic dianhydride (BPDA), which is a dianhydride with a soft structure, and pyromellitic dianhydride (PMDA), which is a dianhydride with a strong structure, can be used to induce polymerization appropriately. The storage modulus and thermal expansion coefficient of the imine film.

However, in order to achieve the above situation, the above-mentioned auxiliary component can be 5 mol% or more and 30 mol% or less based on the total mol number of the aromatic dianhydride monomer, and the main component is based on the aromatic dianhydride monomer. The overall mole number of the body is 70 mole% or more and 95 mole% or less as a reference.

In more detail, the use ratio of the above-mentioned auxiliary components can be 10 mol% or more and 20 mol% or less based on the total mol number of the aromatic dianhydride monomer, and the main component is the aromatic dianhydride The overall molar number of the monomer is 80 mol% or more and 90 mol% or less as a reference.

In addition, in the main component, the molar ratio (=PMDA/BPDA) of the pyromellitic dianhydride (PMDA) to the biphenyl tetracarboxylic dianhydride (BPDA) is preferably 0.45 or more and 1.25 or less In particular, the molar ratio (=PMDA/BPDA) of the pyromellitic dianhydride (PMDA) to the biphenyltetracarboxylic dianhydride (BPDA) is preferably from 0.6 to 0.8.

For reference, in the present invention, the main component and the subsidiary component are only used to clearly distinguish the monomers occupying a relatively more mole% from the monomers occupying a relatively small mole%, instead of dicing into the dominant reaction. The concept of monomers and monomers that do not lead the reaction.

On the other hand, in a specific example, the above-mentioned polyamide acid may include two or more different molecular structures produced by sequential polymerization reactions in the polymer chain. Structured branch. This will be described more specifically in the production method of the polyimide film described below.

Preparation method of polyamide film

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

The monomer mixture prepared by mixing the aromatic diamine monomer and the aromatic dianhydride monomer in a substantially equal molar amount is dissolved in an organic solvent, and the obtained polyamide is stirred under controlled temperature conditions. The amino acid organic solvent solution is used until the polymerization of the aromatic dianhydride monomer and the aromatic diamine monomer is completed, thereby preparing the polyamide acid of the present invention.

Generally, the polyamide acid is obtained at a solid content content of 7 wt% to 25 wt%, preferably 10 wt% to 20 wt%. When the concentration is in the above range, the polyamide acid obtains the appropriate molecular weight and solution viscosity.

The solvent used to prepare the polyamide acid is not particularly limited, and any solvent can be used as long as it can dissolve the polyamide acid, but an amide-based solvent is preferred. Specifically, the above-mentioned solvent may be an aprotic polar solvent, for example, may be selected from N,N'-dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc), N-methyl-pyrrolidone (NMP), gamma-butyrolactone (GBL), diethylene glycol dimethyl ketone (Diglyme) is composed of more than one species, but it is not limited to this , Can be used alone or in combination of two or more as needed. In one example, N,N-dimethylformamide and N,N-dimethylacetamide can be particularly preferably used as the above-mentioned solvent.

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

In a specific example of the above situation, the method for preparing the polyimide film may specifically include: polymerizing a monomer mixture of the aromatic diamine monomer including more than the aromatic dianhydride monomer to prepare the first polyimide film. The step of amide acid; after the completion of the polymerization, add aromatic diamine monomer and aromatic dianhydride monomer to the mixture of residual monomer and polyamide acid to prepare a monomer with a different monomer composition from the previous step The monomer mixture of the mixture is polymerized and the end of the polyamide acid prepared in the previous step is extended to form different branches; after the polymerization is completed, it is additionally in the mixture of residual monomers and polyamide acid The step of mixing aromatic dianhydride monomers to prepare aromatic dianhydride monomers and aromatic diamine monomers to substantially constitute a final monomer mixture of equal moles, and polymerizing to prepare the final polyamide acid; and After the final polyimide film is formed on the support, the step of obtaining a polyimide film by imidization is performed; the monomer mixture may include the above-mentioned amide solvent.

In such a preparation method, in order to obtain desired physical properties, the type of branch and the number of branch extensions can be changed. Specifically, the step of extending the branch can be repeated once or more to 4 times or less.

That is, the polymerization and monomer inputs can be reversed, each polymerization polymerizes a monomer composition with a different composition, and each polymerization induces the formation of branches with a different monomer composition, and the formation of the aforementioned branches is sequentially controlled. .

Therefore, the polyamide acid whose polymerization is finally completed may include two or more types of branched chains with different monomer compositions in the polymer chain.

In the step of preparing the final polyamide acid, the dianhydride monomer additionally mixed into the first polyamide acid may be pyromellitic dianhydride (PMDA).

On the other hand, in the preparation method of the polyimide film described above, fillers can also be added for the purpose of improving various characteristics of the film such as sliding properties, thermal conductivity, electrical conductivity, corona resistance, and ring hardness. The filler material to be added is not particularly limited, but preferred examples include silicon oxide, titanium oxide, aluminum oxide, 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 characteristics of the film to be reorganized and the type of filler added. Generally, the average particle size 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.

If the particle size is smaller than the above range, it becomes difficult to express the restructuring effect, and if it is larger than the above range, the surface properties may be greatly impaired or the mechanical properties may be greatly reduced.

In addition, the addition amount of the filler is not particularly limited, and may be determined according to the characteristics of the film to be reorganized or the particle size of the filler. Generally, the amount of filler added is 0.01 parts by weight to 100 parts by weight, preferably 0.01 parts by weight to 90 parts by weight, and more preferably 0.02 parts by weight to 80 parts by weight relative to 100 parts by weight of polyimide.

If the addition amount of the filler is less than the above range, it is difficult to express the restructuring effect by the filler, and if it is greater than the above range, the mechanical properties of the film may be greatly impaired. The method of adding the filler is not particularly limited, and any known method can be used.

The method of preparing a polyimide film by imidizing the polyimide prepared as described above can use a conventionally known method. Specifically, the thermal imidization method and the chemical imidization method are mentioned.

The thermal imidization method does not make the dehydration ring-closing agent work, but only by A method of heating to carry out the imidization reaction.

On the other hand, the chemical imidization method is a method in which a chemical conversion agent and/or an imidization catalyst acts on polyamide acid to promote imidization.

Here "chemical conversion agent" refers to the dehydration ring-closing agent of polyamic acid, for example, aliphatic acid anhydrides, aromatic acid anhydrides, N,N'-dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower fatty acid Anhydrides, arylphosphonic acid dihalides and thiosulfide halides or a mixture of two or more of them. Among them, from the viewpoint of availability and cost, aliphatic anhydrides such as acetic anhydride, propionic anhydride, and lactic anhydride, or a mixture of two or more thereof can be preferably used.

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

Films can be prepared by either of the thermal imidization method or the chemical imidization method, but the tendency is as follows: the chemical imidization method is easy to obtain a polyimide with various characteristics that are preferably used in the present invention. Imide film.

In the case of using a chemical imidization method in the above-mentioned imidization process, the above-mentioned imidization process preferably includes the following process: coating a film-forming composition including the above-mentioned polyamide acid onto a support On the body, heating is performed on the support to form a gel film, and the process of peeling the gel film from the support; and further heating the gel film to imidize the remaining amic acid. The drying process (hereinafter referred to as "calcination process") is performed.

Hereinafter, the above-mentioned processes will be described in detail.

In order to prepare a gel film, first, a chemical conversion agent and/or an imidization catalyst is mixed with polyamide acid at a low temperature to obtain a film forming composition.

The above-mentioned chemical conversion agent and the imidization catalyst are not particularly limited, but the above-exemplified compounds can be selected and used. In addition, in the above-mentioned gel film preparation process, a curing agent including a chemical conversion agent and an imidization catalyst may be mixed with polyamide acid to obtain a film-forming composition.

The addition amount of the chemical conversion agent is preferably in the range of 0.5 mol to 5 mol, more preferably in the range of 1.0 mol to 4 mol, relative to 1 mol of the amide acid unit in the polyamic acid. Inside. In addition, the addition amount of the imidization catalyst is preferably within the range of 0.05 mol to 2 mol relative to 1 mol of the amide acid unit in the polyamide acid, and particularly preferably 0.2 mol to 2 mol. Within 1 mol range.

If the chemical conversion agent and the imidization catalyst are less than the above-mentioned range, the chemical imidization may be insufficient, which may break in the middle of calcination or decrease the mechanical strength. In addition, if the amounts of the chemical conversion agent and the imidization catalyst are larger than the above range, the imidization may be rapidly advanced and it may become difficult to cast into a film form, which is not preferable.

On the other hand, next, the above-mentioned film forming composition is cast on a support such as a glass plate, aluminum foil, an endless stainless steel belt, or a stainless steel drum in a film form. After that, the film forming composition is heated on the support in a temperature range of 60°C to 200°C, preferably 80°C to 180°C. Thereby, the chemical conversion agent and the imidization catalyst are activated, hardening and/or drying occur locally, thereby forming a gel film. After that, it was peeled off from the support to obtain a gel film.

The above-mentioned gel film is in the intermediate step of hardening from polyamide acid to polyimide, and has self-sustainability. The volatile content of the gel film is preferably 5 wt% to It is in the range of 500% by weight, more preferably in the range of 5% by weight to 200% by weight, and particularly preferably in the range of 5% by weight to 150% by weight. The gel film with the content of volatile components in the above range can be used to avoid the film breakage during the calcination process, the color stain of the film due to dry stains, and the occurrence of characteristic changes.

Flexible copper foil laminated board

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

The flexible copper foil laminated board of the present invention may have a structure in which copper foil is laminated on one side of the polyimide film, or an adhesive layer containing thermoplastic polyimide is added to one side of the polyimide film, The copper foil is laminated while being attached to the adhesive layer.

In the present invention, the thickness of the copper foil is not particularly limited, and may be a thickness that can exhibit sufficient functions according to its use.

As mentioned above, the present invention can provide a glass transition temperature with a desired glass transition temperature due to the combination of a specific dianhydride monomer and a diamine monomer and a specific blending ratio, and a high storage modulus at high temperatures. In addition, a polyimide film that can relax thermal stress and minimize dimensional changes.

The present invention can also provide a flexible copper foil laminated board including the above-mentioned polyimide film and having excellent appearance quality.

Hereinafter, the function and effect of the invention will be described in more detail through specific embodiments of the invention. However, these embodiments are only examples of the invention, and do not thereby define the scope of rights of the invention.

<Example 1>

While keeping the inside of the reaction system at 10°C, DABA, ODA, and BPDA were added to DMF according to the molar ratio shown in Table 1, and stirred for 1 hour to prepare the first polyamide. After confirming the dissolution with the naked eye, p-PDA was added according to the molar ratio shown in Table 1 to dissolve, and then BTDA was added according to the molar ratio shown in Table 1, and stirred for 1 hour to extend to the end of the first polyamide Composition of different branches.

Then, PMDA was added according to the molar ratio shown in PMDA in Table 1 to make the aromatic dianhydride monomer and the aromatic diamine monomer substantially constitute equal molars, and stirred for 1 hour until the viscosity reached 1500 poise. End the polymerization at the time point to prepare the final polyamide acid.

In the final polyamide obtained in this way, based on 100 parts by weight of the polyamide, 50 parts by weight including acetic anhydride/isoquinoline/DMF (weight ratio 46%/13%/41%) are added. After coating the obtained mixture on a stainless steel plate, the obtained mixture was cast with a 400 μm gap using a doctor blade, and then dried with hot air in an oven at 120° C. for 4 minutes to prepare a gel film.

After the gel film prepared in this way was peeled from the stainless steel plate and fixed with frame pins, the frame with the gel film was heat-treated at 400°C for 7 minutes, and then the film was peeled off to obtain an average thickness of 15 μm Polyimide film.

<Example 2>

Except changing the molar ratio of PMDA and BTDA as shown in Table 1, the same method as in Example 1 was used to obtain a polyimide film with a thickness of 15 μm.

<Example 3>

Except changing the molar ratio of PMDA and BTDA as shown in Table 1, the same method as in Example 1 was used to obtain a polyimide film with a thickness of 15 μm.

<Example 4>

Using ODPA instead of BTDA, and changing the composition as shown in Table 1, the same method as in Example 1 was used to obtain a polyimide film with a thickness of 15 μm.

<Example 5>

Except changing the molar ratio of PMDA and ODPA as shown in Table 1, the same method as in Example 4 was used to obtain a polyimide film with a thickness of 15 μm.

<Example 6>

Except changing the molar ratio of PMDA and ODPA as shown in Table 1, the same method as in Example 4 was used to obtain a polyimide film with a thickness of 15 μm.

<Comparative Example 1>

While keeping the inside of the reaction system at 10°C, DABA, ODA, and BPDA were added to DMF according to the molar ratio shown in Table 1 below, and the mixture was stirred for 1 hour. After confirming the dissolution with the naked eye, p-PDA and PMDA were added to dissolve according to the molar ratio shown in Table 1, and then stirred at 20°C for 1 hour and the polymerization was terminated when the viscosity reached 1500 poise to prepare the final polyamide acid. .

In the polyamic acid obtained in this way, based on 100 parts by weight of polyamic acid, 50 parts by weight including acetic anhydride/isoquinoline/DMF (weight ratio 46%/13%/41%) are added. The imidization accelerator, after coating the obtained mixture on a stainless steel plate, cast it with a 400μm gap using a doctor blade, and then bake it at 120°C The inside of the box was dried with hot air for 4 minutes to prepare a gel film.

After the gel film prepared in this way was peeled from the stainless steel plate and fixed with frame pins, the frame with the gel film was heat-treated at 400°C for 7 minutes, and then the film was peeled off to obtain an average thickness of 15 μm Polyimide film.

<Comparative Example 2>

While maintaining the inside of the reaction system at 10°C, ODA, DABA, p-PDA, and BPDA were added to DMF according to the molar ratio shown in Table 1 below and stirred. After confirming the dissolution with the naked eye, it was stirred at 20°C for 1 hour and the polymerization was terminated when the viscosity reached 1500 poise.

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

After the gel film prepared in this way was peeled from the stainless steel plate and fixed with frame pins, the frame with the gel film was heat-treated at 400°C for 7 minutes, and then the film was peeled off to obtain an average thickness of 15 μm Polyimide film.

<Comparative Example 3>

While keeping the inside of the reaction system at 25°C, ODA, p-PDA, and BPDA were added to DMF according to the molar ratio shown in Table 1 below and stirred. After confirming the dissolution with the naked eye, it was stirred at 20°C for 1 hour and the polymerization was terminated when the viscosity reached 1500 poise.

In the polyamide obtained in this way, based on 100 parts by weight of the polyamide, 50 parts by weight including acetic anhydride/isoquinoline/DMF (weight ratio 46%/13%/41%) of the imidization accelerator, after coating the obtained mixture onto a stainless steel plate, cast it with a 400μm gap using a doctor blade, and then dry it with hot air in an oven at 120°C 4 Minutes to prepare a gel film.

After the gel film prepared in this way was peeled from the stainless steel plate and fixed with frame pins, the frame with the gel film was heat-treated at 400°C for 7 minutes, and then the film was peeled off to obtain an average thickness of 15 μm Polyimide film.

<Comparative Example 4>

Except for changing the molar ratios of PMDA, BPDA, and BTDA as shown in Table 1, the same method as in Example 1 was used to obtain a polyimide film with a thickness of 15 μm.

<Comparative Example 5>

Except changing the molar ratios of PMDA, BPDA, and ODPA as in Table 1, the same method as in Example 4 was used to obtain a polyimide film with a thickness of 15 μm.

<Experimental example 1>

The storage modulus reflex point and glass transition temperature (T _g ) values of the polyimide films prepared in Examples 1 to 6 and Comparative Examples 1 to 5 were measured using DMA, and the results are shown in Table 2 below.

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

Referring to Table 2, it can be seen that the polyimide films of Examples 1 to 6 satisfy all the following conditions.

On the contrary, it can be seen that Comparative Example 1 to Comparative Example 5 did not satisfy at least one of the following conditions.

(a) The inflection point of the storage modulus with respect to temperature exists in the range above 340℃

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

(c) The coefficient of thermal expansion is above 7ppm/℃ and below 15ppm/℃

The above description has been made with reference to the embodiments of the present invention, but those with common sense in the technical field to which the present invention belongs can make various applications and modifications within the scope of the present invention based on the above content.

Claims (18)

A polyimide film, which is prepared by imidizing polyimide, the polyimide being polymerized and including selected from pyromellitic dianhydride (PMDA), biphenyltetracarboxylic acid At least three aromatic dianhydride monomers in the group consisting of dianhydride (BPDA), benzophenonetetracarboxylic dianhydride (BTDA) and oxydiphthalic anhydride (ODPA); and together with p-phenylenediamine (p-PDA) is composed of a monomer mixture of a diamine with a carboxylic acid functional group and an aromatic diamine monomer that does not include a diamine with a carboxylic acid functional group, wherein the polyamide is used in the polymer The chain includes two or more branch chains with different monomer compositions produced by successive polymerization reactions. The polyimide film described in item 1 of the scope of patent application, wherein the monomer mixture includes a main component containing the pyromellitic dianhydride (PMDA) and the biphenyltetracarboxylic dianhydride (BPDA) The component, as the aromatic dianhydride monomer, further includes a secondary component selected from the benzophenone tetracarboxylic dianhydride (BTDA) and the oxydiphthalic anhydride (ODPA). The polyimide film as described in item 2 of the scope of patent application, wherein the auxiliary component is 5 mol% or more and 30 mol% or less based on the overall mol number of the aromatic dianhydride monomer The main component is 70 mol% or more and 95 mol% or less based on the total mol of the aromatic dianhydride monomer. The polyimide film described in item 3 of the scope of patent application, wherein the auxiliary component is 10 mol% or more and 20 mol% or less based on the overall mol number of the aromatic dianhydride monomer , The main component is based on the overall molar number of the aromatic dianhydride monomer More than 80 mol% to less than 90 mol%. The polyimide film as described in item 2 of the scope of patent application, wherein the molar ratio of the pyromellitic dianhydride (PMDA) to the biphenyltetracarboxylic dianhydride (BPDA) (=PMDA/ BPDA) is above 0.45 and below 1.25. The polyimide film as described in item 2 of the scope of patent application, wherein the molar ratio of the pyromellitic dianhydride (PMDA) to the biphenyltetracarboxylic dianhydride (BPDA) (=PMDA/ BPDA) is 0.6 or more and 0.8 or less. The polyimide film according to the first item of the scope of patent application, wherein in the monomer mixture, the p-phenylenediamine (p-PDA) is based on the overall molar number of the diamine monomer And it is 55 mol% or more and 80 mol% or less, and the diamine having the carboxylic acid functional group is 5 mol% or more to 15 mol% based on the overall mol number of the diamine monomer Hereinafter, the diamine that does not include the carboxylic acid functional group is 15 mol% or more and 40 mol% or less based on the overall mol number of the diamine monomer. The polyimide film according to item 1 of the scope of patent application, wherein the diamine having the carboxylic acid functional group is selected from 3,5-diaminobenzoic acid (DABA) and 4,4-diamine group One or more of the group consisting of biphenyl-3,3-tetracarboxylic acid (DATA). The polyimide film described in item 8 of the scope of patent application, wherein the diamine having the carboxylic acid functional group is 3,5-diaminobenzoic acid (DABA). The polyimide film as described in the first item of the patent application, wherein the diamine that does not include the carboxylic acid functional group is selected from the group consisting of oxydiphenylamine (ODA), m-phenylenediamine (m-PDA), and One or more of the group consisting of methylene diamine (p-MDA) and m-methylene diamine (m-MDA). The polyimide film as described in item 10 of the scope of patent application, which does not include The diamine including the carboxylic acid functional group is oxydiphenylamine (ODA). The polyimide film as described in item 1 of the scope of the patent application, which satisfies the following conditions (a) to (c): (a) has a storage modulus opposite to the temperature in the range above 340°C Curve point; (b) the glass transition temperature (T _g ) is 350° C. or more; (c) the thermal expansion coefficient is 7 ppm/° C. or more and 15 ppm/° C. or less. A preparation method, which is a method for preparing the polyimide film as described in item 1 of the scope of the patent application, comprising: polymerizing a monomer of the aromatic diamine monomer including more than the aromatic dianhydride monomer The first step of preparing the first polyamide by mixing the mixture; after the completion of the polymerization, the aromatic diamine monomer and the aromatic dianhydride monomer are added to the mixture of the residual monomer and the polyamide to prepare the monomer composition. The monomer mixture of the monomer mixture in the previous step is polymerized and the ends of the polyamide acid prepared in the previous step are extended to form different branches; after the polymerization is completed, the residual monomers and The aromatic dianhydride monomer is mixed with the polyamide acid mixture to prepare the aromatic dianhydride monomer and the aromatic diamine monomer, which essentially constitute the final monomer mixture of equal moles, and polymerize to prepare the final polyamide acid The step; and after the final polyamide acid film is formed to the support, the step of performing imidization to obtain a polyimide film. The preparation method as described in item 13 of the scope of patent application, wherein the step of extending the branch chain is repeated once or more to 4 times or less. The preparation method as described in item 13 of the scope of patent application, wherein In the step of the final polyamide acid, the aromatic dianhydride monomer additionally mixed is pyromellitic dianhydride. A flexible copper foil laminated board, which comprises the polyimide film and copper foil as described in item 1 of the scope of patent application. The flexible copper-foil laminated board described in item 16 of the patent application, wherein copper foil is laminated on one side of the polyimide film, or a thermoplastic polyimide film is added to one side of the polyimide film. The adhesive layer of imine is laminated with the copper foil attached to the adhesive layer. An electronic device comprising the flexible copper foil laminated board as described in item 16 of the scope of patent application.