TW201943764A - Polyimide film for preparing flexible metal foil clad laminate and method of preparing the same, flexible metal foil clad laminate comprising the same and electronic part comprising the same - Google Patents

Abstract

The present invention provides a polyimide film prepared by imidizing a polyamic acid derived from the polymerization of: a diamine monomer comprising first diamine represented by chemical formula (1) and second diamine represented by chemical formula (2); and pyromellitic dianhydride (PMDA). The dielectric constant (Dk) is 3.4 or lower, and the dielectric loss rate (Df) is 0.005 or lower.

Description

Polyimide film for preparing flexible metal foil-clad laminated board and flexible metal foil-clad laminated board including the same

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

Polyimide (PI) is based on a strong aromatic backbone and a very stable chemically stable imine ring. It is the highest level of heat resistance, chemical resistance, electrical insulation, and resistance in organic materials. Chemical and weather-resistant polymer materials.

Therefore, polyimide is favored as an insulating material for microelectronic parts in which the above characteristics are strongly required.

As an example of a microelectronic part, a thin circuit board having a high degree of circuit integration and flexibility in order to be able to cope with the weight reduction and miniaturization of electronic products is mentioned. The polyimide is widely used as an insulating film for a thin circuit board.

For reference, a thin circuit board generally has a structure in which a circuit including a metal foil is formed on a polyimide film. Such a thin circuit board is also referred to as a Flexible Metal Foil Clad Laminate in a broad sense.

On the other hand, recently, electronic devices have various functions built-in, so the above electronic devices are required to have fast computing speed and communication speed. In order to meet the above requirements, a thin circuit board capable of realizing high-speed communication at a high frequency above 2 GHz is being developed. .

In order to achieve high-frequency and high-speed communication, an insulator with high impedance that can maintain electrical insulation even at high frequencies is needed.

The impedance is inversely proportional to the frequency and dielectric constant (Dk) formed in the insulator. In order to maintain insulation at high frequencies, the dielectric constant needs to be as low as possible.

However, the dielectric constant of ordinary polyfluorene imine is about 3.4 to 3.6, which is not an excellent level for maintaining sufficient insulation in high-frequency communication, such as a thin circuit for high-frequency communication above 2 GHz. In the substrate, there is a possibility that the insulation property is partially or entirely lost.

In addition, it is known that the lower the dielectric constant of an insulator, the less stray capacitance and noise can be reduced in a thin circuit board, and the cause of communication delay can be largely eliminated. In terms of the performance of the circuit board, it is the most important factor to reduce the dielectric constant of polyfluorene imine as much as possible.

It should also be noted that high-frequency communication above 2 GHz will inevitably produce dielectric dissipation caused by polyimide.

Dielectric dissipation factor (Df) refers to the degree of wasted power of a thin circuit board, which is closely related to the delay of signal transmission that determines the communication speed. Therefore, it is considered that for the performance of a thin circuit board, the polymer density is reduced as much as possible. The dielectric loss rate of the imine is also an important factor.

Therefore, the fact is that a polyimide film having a relatively low dielectric constant and a relatively low dielectric loss rate needs to be developed.

[Problems to be Solved by the Invention]

An object of the present invention is to provide a polyimide film having a relatively low dielectric constant and a low dielectric loss rate, and a flexible metal foil laminated board including the same.

According to an aspect of the present invention, a polyfluorene prepared by combining a specific diamine monomer including a non-polar aliphatic portion with pyromellitic dianhydride to prepare a polyfluorinated acid and imidizing the polyfluorinated acid. The imine film can suppress moisture absorption which adversely affects the dielectric constant and the dielectric loss rate based on a special structure including a non-polar aliphatic portion in the polyfluorene imine polymer chain.

According to yet another aspect, the flexible metal foil laminate including the polyimide film described above has a desired glass transition temperature and can be realized based on the relatively low dielectric constant and dielectric loss rate of the polyimide film Circuit capable of high-speed communication at high frequency.

Therefore, a substantial object of the present invention is to provide specific examples of the polyfluorene imine film described above.

[Means for solving problems]

In order to achieve the above object, the present invention provides a polyfluorene imide film which is a diamine monomer derived from a first diamine represented by the following chemical formula (1) and a second diamine represented by the following chemical formula (2) Polyammonium phosphonium sulfonimide obtained by polymerization with pyromellitic dianhydride (PMDA) is prepared with a dielectric constant (Dk) of 3.4 or less and a dielectric loss rate (Df) of 0.005 or less.

(1)

(2)

The polyimide film of the present invention has the desired glass transition temperature and dielectric constant, and the dielectric loss rate is improved at the same time. Therefore, the insulation reliability is also higher at high frequencies, and the delay of signal transmission can be minimized. .

Hereinafter, embodiments of the present invention will be described in more detail in the order of "polyimide film", "method for producing polyimide film", and "flexible metal foil laminate" of the present invention.

Prior to this, the terms or words used in this specification and the scope of the patent application for inventions should not be construed as limited to ordinary meanings or meanings in the dictionary. In order for the inventors to explain their inventions in the best way, they should only The principle of the concept of the term may be appropriately defined and interpreted as meanings and concepts conforming to the technical idea of the present invention.

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

In this specification, a singular expression includes a plural expression as long as it does not express otherwise in the text. In this specification, it should be understood that the terms "including," "having," or "having" indicate that there are implemented features, numbers, steps, constituent elements, or a combination thereof, and do not exclude one or more other features, numbers, Existence or additional possibility of steps, constituent elements, or a combination thereof.

Polyimide membrane

The polyfluorene imide film of the present invention is characterized by:
It is obtained by polymerizing a diamine monomer including a first diamine represented by the following chemical formula (1) and a second diamine represented by the following chemical formula (2) and pyromellitic dianhydride (PMDA). It is prepared by imidization of polyphosphonium sulfonate with a dielectric constant (Dk) of 3.4 or less and a dielectric loss rate (Df) of 0.005 or less.

(1)

(2)

Here, in the above chemical formula (1), R1 and R2 are each independently a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkoxy group;
In the above chemical formula (2), R3 is -C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -,-(CH ₂ ) _n1- , or -O (CH ₂ ) _n2 O-, n1 and n2 are each independently an integer of 1 to 10.

In this polyimide film,
(A) The dielectric constant (Dk) is 3.4 or less,
(B) Dielectric loss rate (Df) is 0.005 or less,
(C) The moisture absorption is 2.3% by weight or less,
(D) The glass transition temperature (Tg) is 320 ° C or higher.

In connection with this, polyimide films that satisfy the above four conditions can be used not only as insulating films for flexible metal foil laminates, but also for flexible metal foil laminates manufactured to be used for transmitting signals at high frequencies above 2 GHz. The electrical signal transmission circuit can also ensure its insulation stability and minimize the delay of signal transmission.

The polyfluorene imide film having the above four conditions is a novel polyfluorene imide film which has not been disclosed so far, and the above four conditions will be described in detail below.

＜ Dielectric Constant ＞

Known dielectric constant (Permittivity) is an important characteristic value representing the electrical characteristics of a dielectric (or insulator), that is, a non-conductor. It does not represent the electrical characteristics of a direct current (DC) current, but is related to alternating current. (Alternating Current, AC) The characteristics of electric current, especially alternating current electromagnetic waves, are directly related.

In an insulator (for example, a polyimide film), the + and-moment components, which are usually dispersed in random directions, are arranged corresponding to the AC change of the electromagnetic field applied from the outside of the insulator. That is, the torque component changes in accordance with the direction of the change in the electromagnetic field, thereby allowing electromagnetic waves to travel inside even if it is a non-conductor.

The degree to which the internal moment of a material reacts sensitively to changes in this external electromagnetic field and moves can be expressed as a dielectric constant.

This dielectric constant can usually be explained intuitively by the relative permittivity (Relative Permittivity). The relative permittivity refers to the permittivity of a dielectric with air set to 1 and proportional to this. The relative dielectric constant excludes imaginary numbers and expresses the dielectric constant (Dk) with real numbers.

A higher dielectric constant means that it is easier to transmit electrical energy, so the lower the dielectric constant of an insulator such as a polyfluorene film, the better.

Even so, it has been described that the general polyimide film is not at a level to which sufficient insulation can be maintained in high-frequency communication.

This situation becomes clear when compared with the dielectric constant of a liquid crystal polymer. The dielectric constant of a liquid crystal polymer is known to be approximately 2.9 to 3.3, so it can be considered to be comparable to a dielectric having a dielectric constant greater than the above. Most of the above-mentioned liquid crystal polymers are more excellent as insulators than ordinary polyfluorene imine having an electric constant.

On the contrary, the dielectric constant of the polyfluorene imide film of the present invention may be close to the dielectric constant of the liquid crystal polymer or lower than the dielectric constant of the liquid crystal polymer, specifically 3.4 or less, and 3.0 in detail. Hereinafter, the lower limit may be at least 2.8.

It can be seen that when the engineering properties of the polyimide film are at the highest level, the polyimide film is an ideal form as an insulator.

The meaning of having such a dielectric constant will be specifically described.

Even if all conductors are separated from each other, there is always electrostatic coupling between the conductors due to the electric field. Therefore, even if the layers of the multilayer substrate are electrically separated from each other, they can be regarded as only DC is an open circuit, and in fact, an arbitrary capacitor is connected between the above layers.

On the other hand, the capacitor has the property that the higher the frequency of the current or voltage across the capacitor, the lower the impedance, and the value can be expressed by the following formula.

-Impedance = 1 / (2 * π * f * C); here, f is frequency and C = capacitance.

-C = e * S / d; here, e is the dielectric constant, S is the area of the conductor, and d is the distance.

Generally, on a scale that is visible to the naked eye and can be operated with bare hands, no matter how close the two conductors are, the capacitance (farad) between the conductors is difficult to separate from the pico unit. Printed Circuit Board (PCB) also has very small C between layers. Therefore, even if the circuit operates at a certain high frequency, the insulation between layers can be maintained well.

Conversely, in special cases such as communication equipment operating at a frequency of the gigabit (GIGA) unit, such as an ultra-high frequency of 2 GHz, as shown in the above formula, the impedance becomes low because the frequency is very high, so it may Difficult to maintain insulation.

Therefore, when selecting an insulator, it is necessary to use as low a dielectric constant as possible to minimize electrostatic coupling and capacitance (ie, impedance).

Therefore, the polyfluorene imide film of the present invention has a relatively low dielectric constant as described above, thereby having the advantage of operating at a frequency of a gigabit (GIGA) unit, such as an ultra-high frequency of 10 GHz. It is also easy to maintain insulation in communication equipment.

＜ Dielectric loss rate ＞

The "dielectric loss rate" refers to a force that disappears due to a dielectric body (or an insulator) when the friction of a molecule hinders a molecular movement caused by an alternating electric field.

The value of the dielectric loss rate is usually used as an index indicating the ease of charge loss (dielectric loss). The higher the dielectric loss rate, the easier the charge will disappear. Conversely, the lower the dielectric loss rate, the more the charge will be. It's hard to disappear.

That is, the dielectric loss rate is a measure of electrical loss. The lower the dielectric loss rate, the more the delay of signal transmission due to the electrical loss can be mitigated and the fast communication speed can be maintained.

The above-mentioned dielectric loss rate is a strongly required characteristic of a polyimide film as an insulating film. The polyimide film of the present invention may have a dielectric loss rate of 0.005 or less at a very high frequency of about 2 GHz. It is 0.004 or less, and more specifically, 0.003 or less.

＜ Hygroscopicity ＞

It is known that the moisture absorption rate is a ratio indicating the amount of moisture absorbed by a material. Generally, when the moisture absorption rate is high, the dielectric constant and the dielectric loss rate increase.

Generally, it is known that when water is in a solid state, the dielectric constant is 100 or more, when it is in a liquid state, it is about 80, and when water is in a gaseous state, it is 1.0059.

That is, the water existing in the water vapor state outside the polyimide film does not substantially affect the dielectric constant and the dielectric loss rate of the polyimide film.

However, it exists in a liquid state in a state where water vapor is absorbed in the polyimide film, and in this case, the dielectric constant and the dielectric loss rate of the polyimide film will increase sharply.

That is, even if only a small amount of water is absorbed, the dielectric constant and the dielectric loss rate of the polyfluorene film will change suddenly.

Therefore, it is considered that it is very important to maintain a low moisture absorption rate for a polyimide film as an insulating film.

The polyimide film of the present invention may have a moisture absorption rate of 2.3% by weight or less, 2.0% by weight or less, and 1.7% by weight or less based on the total weight of the polyimide film. The above-mentioned moisture absorption rate is achieved by the structural characteristics of the polyfluoreneimide film of the present invention.

This will be described in more detail later, but the reason is presumed to be that the molecular structure of the polyfluorene imide film of the present invention includes a non-polar portion, and that the fluorene imino group, which is close to hydrophilic, occupies a relatively low ratio.

＜ Glass transition temperature ＞

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

The glass transition temperature is related to the heat resistance of the polyimide film. When considering the application of the insulating film, the higher the glass transition temperature, the better.

However, in the polyimide film, it is difficult to achieve the highest level of glass transition temperature, dielectric constant, and dielectric loss rate at the same time. The reason is presumed that the strong heat resistance of the polyimide film is due to the imine. The chemical stability of the group is achieved, but the imino group exhibits polarity and is therefore relatively weak in moisture absorption.

On the contrary, the present invention provides a polyimide film that simultaneously achieves glass transition temperature, dielectric constant, and dielectric loss rate at a better level. Specifically, the glass transition temperature of the polyimide film of the present invention can be The temperature is about 320 ° C or higher, in particular, 320 ° C or higher and 380 ° C or lower, and particularly preferably 350 ° 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 when lamination is performed, and therefore, a large dimensional change may occur. This is a cause of hindering the appearance quality, and is therefore not good.

On the contrary, when the glass transition temperature is higher than the above range, the temperature required to soften the core layer to a level sufficient to mitigate thermal deformation becomes too high to sufficiently relieve the thermal stress by the existing laminating device, Therefore, there is a possibility that the dimensional change deteriorates instead.

As described above, the polyimide film of the present invention satisfies the above four conditions, so it can be used not only as an insulating film for flexible metal foil laminates, but also to ensure insulation stability at high frequencies and to transmit signals. Minimize latency.

As a specific example of the present invention of a polyfluorene imide film having the above-mentioned conditions, a dianhydride monomer, a diamine monomer, and a blending ratio thereof will be described in detail by the following non-limiting examples.

＜ Diamine monomer ＞

In a specific example, the above-mentioned diamine monomer can be based on the entire mole number thereof so that the first diamine is 50 mol% or more and 80 mol% or less, and the second diamine is 20 mol. % To 50 mol%.

The molecular weight of the second diamine may be 400 g / mol to 600 g / mol, and the molecular weight of the first diamine may be 200 g / mol to 250 g / mol.

Therefore, if the content of the second diamine is increased, the molecular weight of the polyfluorene imine polymer chain formed by the polyfluorine imidization is also increased.

In another aspect, in the total molecular weight of a polyfluorene imine polymer chain that increases with the content of the second diamine, the aromatic portion of the second diamine occupies a larger portion of the portion derived from the diamine monomer. In part, on the contrary, only two amine groups are supplied by one second diamine molecule, so the ratio of the fluorene imino group derived from the diamine to the total molecular weight will be relatively reduced.

In other words, it can be understood that the longer the length of one polyfluorene imine polymer chain, the larger the aromatic portion occupies. Therefore, in the entire polyfluorene imine polymer chain in which the above polymer chain is repeated, fluorene imine The relative ratio of bases is also relatively small.

In this case, the hydrophobicity of the entire polyimide film is also improved, so that a lower moisture absorption rate can be expected.

However, if the content of the second diamine is increased only by considering the moisture absorption rate, the occupation ratio of the fluorene imine group is reduced due to the above-mentioned reasons. There is a possibility that the heat resistance is significantly reduced.

For this reason, the present invention emphasizes that the case where the second diamine is more than 50 mole% based on the entire mole number of the diamine monomer is not good.

In addition, for the opposite reason, when the second diamine is less than 20 mol% based on the entire mole number of the diamine monomer, the moisture absorption rate cannot reach a desired level, which is unfavorable.

The molecular weight of the first diamine is relatively lower than that of the second diamine. The overall molecular weight of the diamine monomer can be adjusted to an appropriate level, which can be understood as adjusting the aromatic moiety in a polyfluorene imine polymer chain. Occupation ratio.

In order to achieve a desired level of heat resistance, the above-mentioned first diamine may also function as another supply source of an amine group for forming a sulfonium imino group.

When the content of the first diamine is larger or smaller than the above range, a disadvantage opposite to that of the second diamine may occur.

The polyamidoimide polymer chain formed by the polyamidofluorene imidization may include an aliphatic portion derived from R1 and R2 of the first diamine and R3 of the second diamine.

Such an aliphatic portion can be appropriately selected in a non-polar manner, and non-limiting examples of the aliphatic portion to facilitate understanding include -CH ₃ , -CF ₃ and the like. As described above, the aliphatic portions derived from R1, R2, and R3 have non-polarity, and the hygroscopicity of the polyfluorene imine polymer chain decreases.

In another aspect, in the case where the aliphatic portion is included in the polyamic acid, the ratio of the amino acid group which has a very large effect on the increase in hygroscopicity will be relatively low in the entire polyamic acid. Therefore, it can play a positive role in reducing the hygroscopicity of a polyimide film including such a polyamic acid.

It has been explained that it is closely related to the dielectric constant and the dielectric loss rate. Therefore, in summary, the aliphatic portion from R1, R2, and R3 can be understood as giving the polyfluorene imide film of the present invention a low dielectric constant and a low dielectric constant. The main element of the loss rate.

In addition, the aliphatic portion from the above-mentioned R1, R2 and R3 can improve the non-polarity, provide a better level of flexibility to the polyimide film, reduce the defective rate in the film forming process, and ensure the suitability for manufacturing softness. Level glass transition temperature and thermal expansion coefficient of metal foil laminates.

As described above, in order to achieve the desired moisture absorption rate, dielectric constant, dielectric loss rate, flexibility, glass transition temperature, and thermal expansion coefficient, the molecular weight of the aliphatic portion can be determined by the molecular weight of one polyimide polymer chain. The overall molecular weight is 5% to 20%, and in detail, it may be 6% to 17%.

If the molecular weight of the aliphatic portion is larger than the above range, the mechanical properties of the polyimide film will be reduced, and it will be difficult to achieve a level of glass transition temperature and thermal expansion coefficient suitable for manufacturing flexible metal foil laminates. If the molecular weight is smaller than the above range, it will be difficult to achieve Desired levels of hygroscopicity, dielectric constant, and dielectric loss are not satisfactory.

In a specific example, the R1 and R2 may be an alkyl group having a non-polar molecular weight without occupying an excessive molecular weight ratio. In detail, the R1 and R2 may be methyl groups, respectively.

The R3 may be a substituent having a non-polar molecular weight that does not occupy too much molecular weight, and may be -C (CF ₃ ) ₂ -or -C (CH ₃ ) ₂ -in detail.

In the above-C (CF ₃ ) _2- , fluorine can contribute to lowering the dielectric constant and can exhibit strong non-polarity, and thus can be particularly preferably used as R3.

In a specific example, the first diamine may be 4,4'-diamino-2,2'-dimethylbiphenyl (4,4'-Diamino-2,2'-dimethylbiphenyl, m-methyl) Aniline (m-Tolidine)).

In another specific example, the second diamine may be 2,2-bis [4- (4-aminophenoxyphenyl)] hexafluoropropane (2,2-Bis [4- (4-aminophenoxy phenyl)] hexafluoropropane (HFBAPP).

＜ dianhydride monomer ＞

Above, it has been explained that the diamine monomer may have a relatively large molecular weight.

The molecular weight of a polyimide polymer chain formed by the above polyimide amidation is too large (for example, a polymer chain is more than 2000) and the longer the chain length, the more inevitable is the polyimide polymer There are relatively few amidine groups in the chain as a whole.

In this case, other mechanical properties such as heat resistance, storage modulus, and loss of elastic modulus of the polyimide film are severely impaired, so it is not good.

In consideration of such a case, a monomer having a relatively small molecular weight may be used as the dianhydride monomer.

Therefore, as the dianhydride monomer, pyromellitic dianhydride (PMDA) having a molecular weight as small as 218 is preferable.

The above pyromellitic dianhydride (PMDA) can also be regarded as a dianhydride monomer having a relatively strong structure.

It is well known that a solid structured unit is suitable for achieving a high elastic modulus.

Therefore, the above pyromellitic dianhydride (PMDA) is preferable in that it can impart appropriate elasticity to the polyfluorene imide film produced by the polyphosphonium fluorination.

Preparation method of polyimide film

The polyimide film of the present invention is obtained from a solution of a polyamic acid that is a precursor of the polyimide.

A polyamidic acid solution is prepared by dissolving a monomer compound prepared by blending an aromatic diamine monomer and an aromatic dianhydride monomer into an organic solvent in a substantially equimolar amount, and controlling the The obtained polyamine organic solvent solution is stirred under a good temperature condition until the polymerization of the aromatic dianhydride monomer and the aromatic diamine monomer is completed.

Generally, the polyamic acid solution is obtained at a concentration of 5 to 35% by weight of the solid content, preferably 10 to 30% by weight.

When the concentration is in the above range, the polyamidic acid solution obtains an appropriate molecular weight and solution viscosity.

The solvent used to synthesize the polyamine solution is not particularly limited, and any solvent may be used as long as it is a solvent that dissolves the polyamino acid, but a amine-based solvent is preferred.

Specifically, the solvent may be an organic polar solvent, and in detail, it may be an aprotic polar solvent. For example, the solvent may be selected from the group consisting of N, N'-dimethylformamide (DMF), N , N'-dimethylacetamide, N-methyl-pyrrolidone (NMP), γ-butyrolactone (GBL), diethylene glycol dimethyl ether (Diglyme) , But it is not limited to this, and can be used alone or in combination of two or more kinds as required.

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

Therefore, in order to obtain the polyfluorene imine film of the present invention, it is preferable to prepare a polyamic acid solution obtained by performing the following steps (a) to (c), and the polyamino acid The solution is imidized.

Therefore, the present invention provides a method for preparing a polyfluoreneimide film.

The above preparation method may include:
(A) a step of adding the diamine monomer and the dianhydride monomer to an organic polar solvent;
(B) a step of polymerizing the diamine monomer and the dianhydride monomer with each other in the organic polar solvent to obtain polyamic acid;
(C) a step of forming the polyfluorene acid onto a support, and then performing a heat treatment at a temperature of 200 ° C. to 400 ° C. to obtain the polyfluorine imine-imidized polyfluorine imine film;

However, depending on the type of monomer and the desired physical properties of the polyimide film, all monomers can be added at once in step (a) above, or each monomer can be added sequentially. Local aggregation will occur.

The final polyamic acid prepared through the steps (a) to (b) has a molecular structure in the form of branched chains having different physical properties.

The position, length of the branched chain, and the type and content of the monomers constituting the branched chain can be adjusted to finely adjust the physical properties of the polyimide film obtained by the imidization of the polyimide and the polyimide film, such as the dielectric constant, Dielectric loss rate, glass transition temperature, moisture absorption rate, etc.

In addition, in the "preparation process of a polyamic acid solution", a filler can be added for the purpose of improving various properties of films such as sliding properties, thermal conductivity, electrical conductivity, corona resistance, and ring hardness.

The filler 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 diameter of the filler is not particularly limited, and can be determined according to the characteristics of the film to be reorganized and the type of filler to be added.

Generally, 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, and particularly preferably 0.1 μm to 25 μm.

If the particle diameter is smaller than the above range, it becomes difficult to exhibit a recombination effect, and if it is larger than the above range, the surface properties may be significantly impaired or the mechanical characteristics may be significantly reduced.

In addition, the amount of the filler to be added is not particularly limited, and can be determined according to the characteristics of the film to be reorganized, the particle diameter of the filler, and the like.

Generally, the filler may be added in an amount of 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight relative to 100 parts by weight of polyimide.

If the amount of the filler added is less than the above range, it is difficult to exhibit the recombination effect achieved by the filler, and if it is larger than the above range, there is a possibility that the mechanical characteristics of the film are significantly impaired.

The method for adding the filler is not particularly limited, and any known method can be used.

As a method for preparing a polyimide film by polyimidizing the polyamidic acid solution prepared as described above, a conventionally known method can be used.

Specific examples thereof include a thermal amidine method, a chemical amidine method, or a composite amidine method in which a thermal ammine method and a chemical ammine method are used in combination.

The thermal fluorination method is a method in which a polyfluorinated acid solution is fluorinated only by heating without using a catalyst such as a dehydrating agent. After the polyfluorinated acid is formed on a support, the temperature is 40 ° C. The temperature is gradually raised in a temperature range of 400 ° C., preferably 40 ° C. to 300 ° C., and heat treatment is performed for 1 to 8 hours to obtain the polyfluorene imine film obtained by the polyfluorine imidization.

The chemical ammonium imidization method is a method in which a catalyst such as a dehydrating agent and / or an imidizing agent is used to promote the imidization of a polyacrylic acid solution.

The composite fluorene imidization method can obtain a polyfluorene imine film by adding a dehydrating agent and a fluorene imidization catalyst to a polyfluorine acid solution to form a film on a support, at 80 ° C to 200 ° C. Preferably, heating is performed at 100 ° C to 180 ° C to partially harden and dry, and then heating at 200 ° C to 400 ° C for 5 seconds to 400 seconds.

On the other hand, examples of the dehydrating agent include aliphatic acid anhydrides, aromatic acid anhydrides, N, N'-dialkylcarbodiimides, halogenated lower aliphatic, halogenated lower fatty acid anhydrides, arylphosphonic acid dihalides, and sulfites. Samarium halide or a mixture of two or more of them.

Among these, from the viewpoints of availability and cost, aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and lactic acid anhydride, or a mixture of two or more of them can be preferably used.

Examples of the fluorene imidating agent include aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines.

Among them, from the viewpoint of reactivity as a catalyst, one selected from heterocyclic tertiary amines is particularly preferably used.

Specifically, quinoline, isoquinoline, β-methylpyridine, pyridine and the like are preferably used.

In the case where the chemical fluorene imidization method is used in the fluorene imidization process, the fluorene imidization process preferably includes: coating a composition for forming a film including the polyphosphonium acid solution onto a support A process of forming a gel film by performing heat treatment on a support at a temperature range of 40 ° C to 300 ° C, and peeling the gel film from the support; and further heating the gel film to remove the remaining ammonium acid ( amic acid) a process of imidization and drying (hereinafter, also referred to as "calcination process").

Hereinafter, each of the above processes will be described in detail.

In order to prepare a gel film, a dehydrating agent and / or an imidizing agent are first mixed into a polyamic acid solution at a low temperature to obtain a film-forming composition.

The above-mentioned dehydrating agent and amidine imidating agent are not particularly limited, but the above-exemplified compounds may be optionally used.

In addition, in the manufacturing process of the gel film, a hardening agent including a chemical conversion agent and a fluorinated imidization catalyst may be mixed into a polyamic acid solution to obtain a film-forming composition.

The addition amount of the dehydrating agent is preferably in the range of 0.5 to 5 mol, and more preferably in the range of 1.0 to 4 mol based on 1 mol of the glutamic acid group in the polyamic acid. .

In addition, the addition amount of the fluorene imidating agent is preferably in the range of 0.05 mol to 3 mol, and particularly preferably 0.2 mol to 2 relative to 1 mol of the sulfamic acid group in the polyamic acid. Mohr's range.

When the dehydrating agent and the amidine imidating agent are smaller than the above range, there is a case where the chemical amidine imidization is insufficient and it is broken in the middle of calcination or the mechanical strength is lowered.

In addition, if the amounts of the dehydrating agent and amidine imidating agent are larger than the above-mentioned range, the amidine imidization may be rapidly advanced and it may become difficult to cast into a film shape, which is not preferable.

On the other hand, the film-forming composition is then cast in a film shape onto a support such as a glass plate, an aluminum foil, an endless stainless steel tape, or a stainless steel drum.

Thereafter, the composition for film formation is heated on the support in a temperature range of 80 ° C to 200 ° C, preferably 100 ° C to 180 ° C.

Thereby, the dehydrating agent and the sulfonium imidating agent are activated, and local hardening and / or drying occurs, thereby forming a gel film.

Thereafter, the gel film was obtained by peeling from the support.

The gel film is in an intermediate stage of curing from polyfluorene acid to polyimine, and has self-sustaining property.

Flexible copper foil laminated board

The present invention provides a flexible metal foil laminate including the polyimide film and a conductive metal foil.

The metal foil to be used is not particularly limited, but when the flexible metal foil laminate of the present invention is used for electronic equipment or electrical equipment, for example, it may include copper or a copper alloy, stainless steel or an alloy thereof, nickel or Metal foil of nickel alloy (also including alloy 42), aluminum or aluminum alloy.

In general flexible metal foil laminates, copper foils called rolled copper foils and electrolytic copper foils are often used, and the above-mentioned copper foils can also be preferably used in the present invention.

The surface of the metal foil may be coated with a rust-proof layer, a heat-resistant layer, or an adhesive layer.

In this invention, the thickness of the said metal foil is not specifically limited, What is necessary is just the thickness which can perform a sufficient function according to the use.

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

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

The electrical signal transmission circuit may be an electronic component that transmits signals at a high frequency of at least 2 GHz, a high frequency of at least 5 GHz, and a high frequency of at least 10 GHz.

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

[Inventive effect]

As described above, the present invention can provide a desired glass transition temperature and relatively low hygroscopicity due to a combination of a specific dianhydride monomer and a diamine monomer and a specific blending ratio thereof. Polyimide film in which the increase in the dielectric constant and the dielectric loss rate caused are suppressed.

The present invention can also provide a flexible metal foil laminate including a polyimide film as described above and used as an electric transmission circuit capable of achieving high-frequency communication above 2 GHz.

Hereinafter, the functions and effects of the invention will be described in more detail with reference to specific examples of the invention. However, these embodiments are merely examples of the invention and do not thereby define the scope of rights of the invention.

<Example 1>

While maintaining the inside of the reaction system at 10 ° C, PMDA was added to DMF in accordance with the molar ratio shown in Table 1 below, and stirred for 1 hour.

After confirming the dissolution with the naked eye, m-tolidine was added at a molar ratio shown in Table 1 to dissolve it, and HFBAPP was added at a molar ratio shown in Table 1 and stirred for 1 hour to prepare a polymer. Amino acid.

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

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

<Example 2>

Except that the molar ratio of m-tolidine to HFBAPP was changed as in Table 1, a polyimide film having a thickness of 15 μm was obtained by the same method as in Example 1.

<Example 3>

Except that the molar ratio of m-tolidine to HFBAPP was changed as in Table 1, a polyimide film having a thickness of 15 μm was obtained by the same method as in Example 1.

〈Comparative example 1〉

Except that the molar ratio of m-tolidine to HFBAPP was changed as in Table 1, a polyimide film having a thickness of 15 μm was obtained by the same method as in Example 1.

〈Comparative example 2〉

Except that the molar ratio of m-tolidine to HFBAPP was changed as in Table 1, a polyimide film having a thickness of 15 μm was obtained by the same method as in Example 1.

〈Comparative example 3〉

Except that the molar ratio of m-tolidine to HFBAPP was changed as in Table 1, a polyimide film having a thickness of 15 μm was obtained by the same method as in Example 1.

〈Comparative example 4〉

In accordance with the molar ratio shown in Table 1, oxydianiline (ODA) was added instead of m-tolidine and HFBAPP, except that the thickness was obtained by the same method as in Example 1. 15 μm polyimide film.

〈Comparative example 5〉

In accordance with the molar ratio shown in Table 1, ODA and p-phenylene diamine (PPD) were added instead of m-tolidine and HFBAPP. Method to obtain a polyimide film with a thickness of 15 μm.

〈Comparative example 6〉

PMDA and Biphenyltetracarboxylic Dianhydride (BPDA) were added in accordance with the molar ratio shown in Table 1 instead of separately adding PMDA. Except that, a thickness of 15 μm was obtained by the same method as in Example 1. Polyimide film.

〈Comparative example 7〉

A BPDA was added in place of PMDA in accordance with the molar ratio shown in Table 1. A polyimide film having a thickness of 15 μm was obtained by the same method as in Example 1.

[Table 1]

＜ Experimental Example 1 ＞

The glass transition temperature and moisture absorption rate of the polyfluorene imide film obtained above were measured in the following manner.

Thereafter, a roll-to-roll lamination was performed, and a copper foil was laminated on both sides of the polyimide film to prepare a flexible metal foil laminate, and the dielectric constant and the dielectric loss rate were measured in the following manner.

The above results are shown in Table 2 below.

1) Glass transition temperature

The glass transition temperature was obtained by using DMA to determine the loss elastic modulus and storage modulus of each film, and the inflection point was measured as the glass transition temperature in the tangent graph.

2) Moisture absorption

According to the method of American Society for Testing Materials (ASTM) D570, the polyimide film was cut into squares with a size of 5 cm × 5 cm to prepare test pieces, and the cut test pieces were placed in an oven at 50 ° C. The weight was measured after internal drying for more than 24 hours. The test piece whose weight was measured was immersed in water at 23 ° C. for 24 hours, and then the weight was measured again. The difference in weight obtained here was expressed in% to measure the moisture absorption.

3) Measurement of dielectric constant and dielectric loss rate

The flexible metal foil laminate was allowed to stand for 72 hours, and the dielectric constant and the dielectric loss rate were measured using a resistance meter Agilent 4294A.

[Table 2]

As shown in Table 2, it can be confirmed that the polyimide film prepared according to the embodiment of the present invention not only has significantly lower moisture absorption rate, dielectric constant, and dielectric loss rate, but also has a glass transition temperature at a desired level. The polyfluoreneimide film satisfies the following conditions as described above.

(A) The dielectric constant (Dk) is 3.4 or less;
(B) Dielectric loss rate (Df) is 0.005 or less;
(C) Hygroscopicity is less than 2.3% by weight;
(D) The glass transition temperature (Tg) is 320 ° C or higher.

It is understood that such a result is achieved by combining a specific diamine monomer which generates an aliphatic portion with PMDA having a relatively low molecular weight, and the content of each monomer plays a decisive role.

On the contrary, it was confirmed that at least one of the moisture absorption rate, the dielectric constant, the dielectric loss rate, and the glass transition temperature of Comparative Examples 1 to 3 in which the content of the diamine monomer deviated from the range of the present invention significantly decreased.

In addition, it was confirmed that the dielectric constant, the dielectric loss rate, and the moisture absorption rate of Comparative Examples 4 and 5 each having a diamine monomer different from the Examples were significantly different from those of the Examples.

In particular, Comparative Examples 4 and 5 show a dielectric constant and a dielectric loss rate that are significantly higher than those of the Examples, and it is presumed that these Comparative Examples are difficult to use for electronic components that transmit signals at high frequencies in gigabit units.

In addition, the glass transition temperature of Comparative Example 4 and Comparative Example 5 is much larger than the preferred range disclosed in the present invention, and it has been shown that this situation is very unfavorable to the processing of the polyimide film.

On the other hand, it was confirmed that the glass transition temperature of Comparative Example 6 including BPDA and PMDA as dianhydride monomers and Comparative Example 7 including only BPDA as dianhydride monomers were significantly different from the examples.

The above has been described with reference to the embodiments of the present invention. However, those skilled in the art to which the present invention pertains can perform various applications and modifications within the scope of the present invention based on the foregoing.

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Claims (14)

A polyfluorene imide film comprising a pyromellitic dianhydride derived from a diamine monomer including a first diamine represented by the following chemical formula (1) and a second diamine represented by the following chemical formula (2); Polyimide obtained by polymerization is prepared by imidization, the dielectric constant is 3.4 or less, and the dielectric loss rate is 0.005 or less: (1) (2) in the formula (1), R1 and R2 are each independently C alkyl or C ₁ -C ₆ alkoxy ₁ -C _6; and in the formula (2), R3 is - C (CH ₃ ) _2- , -C (CF ₃ ) ₂ -,-(CH ₂ ) _n1- , or -O (CH ₂ ) _n2 O-, wherein n1 and n2 are each independently an integer of 1 to 10 . The polyimide film according to item 1 of the scope of the patent application has a glass transition temperature of 320 ° C or higher. The polyimide film according to item 1 of the scope of patent application has a thermal expansion coefficient of 10 ppm / ° C to 25 ppm / ° C. The polyfluorene imide film according to item 1 of the scope of patent application, wherein the first diamine is 50 mol% or more and 80 mol% or less based on the entire mole number of the diamine monomer. The second diamine is 20 mol% or more and 50 mol% or less. The polyimide film according to item 1 of the scope of the patent application, wherein the polyimide polymer chain formed by the polyimide amidation includes R1 and R2 from the first diamine and The aliphatic portion of R3 of the second diamine. The polyimide film according to item 5 of the application, wherein the molecular weight of the aliphatic portion is 5% to 20% based on the overall molecular weight of one of the polyimide polymer chains. The polyfluorene imide film according to item 1 of the scope of the patent application, wherein R1 and R2 are methyl groups, and R3 is -C (CF ₃ ) ₂ -or -C (CH ₃ ) _2- . The polyfluorene imide film according to item 1 of the scope of the patent application, wherein the first diamine is 4,4'-diamino-2,2'-dimethylbiphenyl (m-toluidine). The polyfluoreneimide film according to item 1 of the scope of the patent application, wherein the second diamine is 2,2-bis [4- (4-aminophenoxyphenyl)] hexafluoropropane (HFBAPP) . A method for preparing a polyfluoreneimide film, which is a method for preparing a polyfluoreneimide film according to item 1 of the scope of patent application, which comprises: A step of adding the diamine monomer and the dianhydride monomer to an organic polar solvent; A step of polymerizing the diamine monomer and the dianhydride monomer with each other in the organic polar solvent to obtain polyamic acid; and The step of forming the polyfluorene acid onto a support, and then performing a heat treatment at a temperature of 200 ° C. to 450 ° C. to obtain the polyfluorine imine-imidized polyfluorine imine film. A flexible metal foil laminated board includes the polyimide film and the conductive metal foil according to item 1 of the scope of patent application. The flexible metal foil laminated board according to item 11 of the scope of patent application, wherein a metal foil is laminated on one side of the polyimide film, Alternatively, an adhesive layer containing a thermoplastic polyimide is added to one side of the polyimide film, and the metal foil is laminated in a state where the metal foil is attached to the adhesive layer. An electronic part includes the flexible metal foil laminated board according to item 12 of the scope of patent application as an electrical signal transmission circuit. The electronic component according to item 13 of the scope of patent application, wherein the electrical signal transmission circuit transmits signals at a high frequency of at least 2 GHz.