TW202124526A - Method for producing polyimide precursor and polyimide - Google Patents

Abstract

The present invention relates to a method for producing polyimide precursor and a polyimide. The polyimide precursor consisted of a first polyamic acid, a second polyamic acid and a third polyamic acid is produced by a first reaction, a second reaction and a third reaction. The polyimide precursor is polymerized by a specific tetracarboxylic dianhydride monomer and diamine monomer, such that the polyimide precursor has lower dielectric constant and dielectric loss factor, further decreasing insertion loss, therefore enhancing transmission rate of a flexible circuit substrate.

Description

Preparation method of polyimide precursor and polyimide

The present invention relates to a polyimide precursor, and in particular provides a method for preparing a polyimide precursor with low dielectric constant and dielectric loss factor and the prepared polyimide.

With the development of the technology industry, high-frequency transmission has become the main transmission method for wireless communication products, so high-frequency substrates with fast transmission rates are currently the focus of development. Among them, in order to meet the requirements of high-frequency transmission, the signal loss of the substrate must be effectively reduced.

Generally speaking, the signal loss in the substrate refers to the insertion loss of the signal, and the insertion loss is the sum of reflection loss, material loss, and radiation loss. Among them, material loss includes dielectric loss and conductor loss. The dielectric loss is controlled by the insulating layer, and the conductor loss is related to the conductivity and surface roughness of the conductive layer. Secondly, the dielectric loss is calculated by the following formula (I), and it can be seen from the formula (I) that reducing the dielectric constant and dielectric loss factor of the material can effectively reduce the dielectric loss and help high-frequency transmission.

In formula (I), Dk represents the dielectric constant, Df represents the dielectric loss factor, and f represents the frequency.

Among the existing charge transport substrates, polyimide copper clad laminates are widely used in electronic products because of their lightness and flexibility. However, the conventional polyimide film has a relatively high dielectric constant and dielectric loss factor, so it cannot meet the application requirements of high-frequency transmission.

In view of this, there is an urgent need to provide a preparation method of polyimide precursor and polyimide to improve the defects of conventional polyimide that has an excessively high dielectric constant and dielectric loss factor.

Therefore, one aspect of the present invention is to provide a method for preparing a polyimide precursor. The block copolymerized monomers are arranged regularly, thereby reducing the resistance of charge transfer, so it can meet the requirements of high-frequency transmission.

Another aspect of the present invention is to provide a polyimide, which is prepared by heating the polyimide precursor, and the polyimide precursor is prepared by the aforementioned manufacturing method.

According to one aspect of the present invention, a method for preparing a polyimide precursor is provided. In this production method, the first tetracarboxylic dianhydride monomer and the first diamine monomer are first reacted to form the first polyamide acid. Then, a second reaction is performed on the first polyamide acid, the second tetracarboxylic dianhydride monomer, and the second diamine monomer to form a block polyamide acid. This block polyamide is made from the first poly The amide acid and the second polyamide acid are composed, wherein the second polyamide acid is formed by the second tetracarboxylic dianhydride monomer and the second diamine monomer. Then, a third reaction is performed on the block polyamide acid, the third tetracarboxylic dianhydride monomer, and the third diamine monomer to form a polyimide precursor. The polyimide precursor is composed of block polyamide and the third polyamide. The third polyamide is composed of the third tetracarboxylic dianhydride monomer and the third diamine monomer. form. Either the first tetracarboxylic dianhydride monomer or the second tetracarboxylic dianhydride monomer may have a tetracarboxylic dianhydride monomer having an ether group in the main chain, and the third diamine monomer may have Diamine monomers with ether groups or diamine monomers with alkyl groups in the side chain.

According to an embodiment of the present invention, based on the content of the aforementioned polyimine precursor being 100 mol%, the content of the third polyamide is 10 mol% to 30 mol%.

According to another embodiment of the present invention, based on the content of the polyimide precursor being 100 mole percent, the first tetracarboxylic dianhydride monomer or the second tetracarboxylic dianhydride monomer is formed by The content of the first polyamide or the second polyamide is 10 mol% to 60 mol%.

According to another embodiment of the present invention, based on the content of the polyimide precursor being 100 mole percent, the other of the aforementioned first tetracarboxylic dianhydride monomer or second tetracarboxylic dianhydride monomer is formed The content of the first polyamide or the second polyamide is 20 mol% to 75 mol%.

According to another embodiment of the present invention, the aforementioned first diamine monomer and second diamine monomer are not diamine monomers with ether groups in the main chain or diamine monomers with alkyl groups in the side chains.

According to yet another embodiment of the present invention, the aforementioned third tetracarboxylic dianhydride monomer is not a tetracarboxylic dianhydride monomer having an ether group in the main chain.

According to still another embodiment of the present invention, the total solid content of the aforementioned polyimide precursor is 10 wt% to 25 wt%.

According to another aspect of the present invention, a polyimide is provided. The polyimide is formed by heating the polyimine precursor, and the polyimine precursor is prepared by the aforementioned manufacturing method. Among them, each molecular chain of the polyimide is composed of the first polyamide, the second polyamide, and the third polyamide.

According to an embodiment of the present invention, the dielectric loss factor of the aforementioned polyimide is 0.003 to 0.005 and the dielectric constant is 3.0 to 3.7.

Applying the preparation method of the polyimide precursor and the polyimide of the present invention, the specific tetracarboxylic dianhydride monomer and the diamine monomer are used to carry out the stepwise reaction, and the first polyimide can be formed , A block polyimide precursor composed of the second polyamide and the third polyamide. The first polyimide can provide rigid molecular segments to the polyimide precursor, so that the subsequently prepared polyimide has good dimensional stability. The long molecular chain segments in the second polyamide and the third polyamide can effectively reduce the density of the imine group of the polyimide produced, and reduce the dielectric loss factor, thereby helping to reduce subsequent The copper foil circuit transmits the energy loss of the signal. In addition, the long molecular chain segment of the third polyimide also helps to improve the coatability of the polyimide precursor, which can meet application requirements.

The manufacture and use of the embodiments of the present invention are discussed in detail below. However, it can be understood that the embodiments provide many applicable inventive concepts, which can be implemented in various specific contents. The specific embodiments discussed are for illustration only, and are not intended to limit the scope of the present invention.

The polyimide precursor of the present invention is a block polymer composed of a first polyamide (A1), a second polyamide (A2) and a third polyamide (A3). According to the production method of the polyimide precursor described below, the prepared polyimine precursor may have the following example structures of regular blocks as shown in the following formulas (i-1) to (i-3). It is understandable that the polyimide precursor of the present invention is not limited to the following exemplified structures. According to the production method described later, a person with ordinary knowledge in the technical field to which this case belongs can understand other structures of the polyimide precursor.

The aforementioned first polyamide (A1), second polyamide (A2) and third polyamide (A3) are all formed by the reaction of tetracarboxylic dianhydride monomer and diamine monomer. Among them, based on the structure of the polyamide acid to be prepared, the selected tetracarboxylic dianhydride monomer and diamine monomer can be independently rigid monomers or flexible monomers.

The "rigid monomer" referred to in the present invention means that the monomer structure is relatively rigid, and it is not easy to produce rotational changes in the molecular structure. Therefore, the rigid monomer helps to enhance the structural rigidity of the formed polymer and improve the structure of the polymer. The dimensional stability of the manufactured product. It is understandable that the main chain structure of rigid monomers is generally composed of benzene rings. In other specific examples, the benzene ring of the rigid monomer may also be linked by a ketone group, an amide group, an ester group and/or other appropriate rigid groups.

The term "flexible monomer" referred to in the present invention is a term relative to the aforementioned rigid monomer. Accordingly, flexible monomers are prone to rotational changes in molecular structure, and/or have side chain groups with more flexible structures. It should be noted that although the flexible monomer is more flexible, its main chain structure can also be composed of benzene rings. Among them, the benzene rings of the main chain structure can be connected by ether groups, or the benzene rings of the main chain structure can have an alkane. Substituent groups, and have a longer monomer molecular structure. Since the flexible monomer is a monomer with a long molecular structure, the polyimine segment produced subsequently has a lower density of the imine functional group, which can avoid the high molecular weight caused by the water absorption of the imine functional gene. Electric loss factor, so it can effectively reduce the dielectric constant (Dk) and dielectric loss factor (Df) of the material. In some cases, when the monomer has a longer molecular chain structure, since such monomers can also effectively reduce the density of the imine functional groups of the polyimine segment prepared, these monomers can be assigned It is a "flexible monomer". In other words, the "flexible monomer" in this case mainly helps to reduce the density of the imine functional group of the polyimine segment formed.

In the preparation method of the polyamide precursor of the present invention, the tetracarboxylic dianhydride monomer (a1) and the diamine monomer (b1) undergo a first reaction to form the polyamide acid (A1). Then, a second reaction is performed on the polyamide acid (A1), the tetracarboxylic dianhydride monomer (a2) and the diamine monomer (b2) to form a block polyamide acid. This block polyamide is composed of polyamide (A1) and polyamide (A2), among which polyamide (A2) is composed of tetracarboxylic dianhydride monomer (a2) and diamine Monomer (b2) is formed by reaction.

In order to improve the structural rigidity of the prepared polyimide precursor, the diamine monomer (b1) and the diamine monomer (b2) can be selected as rigid monomers. In some specific examples, the diamine monomer (b1) and the diamine monomer (b2) of the rigid monomer may respectively include, but are not limited to, p-phenylenediamine (p-PDA), 4,4'-diamino Benzoaniline (DABA), other suitable diamine monomers, or any mixture of the above monomers.

When the aforementioned first reaction is carried out, the tetracarboxylic dianhydride monomer (a1) may be a rigid monomer. In some specific examples, the tetracarboxylic dianhydride monomer (a1) of the rigid monomer can be 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3', 4,4'-Biphenyltetracarboxylic dianhydride (s-BPDA), p-phenylbis(trimellitic acid ester) bistetracarboxylic dianhydride (TAHQ), pyromellitic dianhydride (PMDA), others Appropriate tetracarboxylic dianhydride monomer, or any mixture of the above monomers. According to the foregoing description, when the tetracarboxylic dianhydride monomer (a1) and the diamine monomer (b1) are both rigid monomers, the polyamide acid (A1) formed by the reaction can have a relatively rigid polymer The main chain structure has higher structural rigidity.

In the first reaction, the molar ratio of the tetracarboxylic dianhydride monomer (a1) to the diamine monomer (b1) may preferably be 0.9:1 to 1:1. The first reaction is carried out by using the reaction temperature and other reaction parameters that are well known to those with ordinary knowledge in the technical field of the present invention, so it will not be repeated here. It is understandable that the polyamide acid (A1) prepared by the first reaction is a colloidal solution. The viscosity of the colloidal solution containing polyamide acid (A1) may be 20 cps to 12000 cps, and preferably 100 cps to 6000 cps.

Based on the prepared polyimide precursor content of 100 mol%, the content of polyamide acid (A1) can be 20 mol% to 75 mol%, preferably 20 mol% to 60 mol% Ear percentage, and more preferably 30 mol% to 50 mol%.

When the aforementioned second reaction is performed, the tetracarboxylic dianhydride monomer (a2) can be a monomer with a long chain structure (such as the aforementioned flexible monomer). In some embodiments, the tetracarboxylic dianhydride monomer (a2) may include, but is not limited to, a tetracarboxylic dianhydride monomer having an ether group in the main chain, other suitable tetracarboxylic dianhydride monomers, or the above-mentioned monomers The arbitrary mix. In some specific examples, the tetracarboxylic dianhydride monomer (a2) of the monomer with a long chain structure may be p-phenylbis(trimellitic acid dianhydride) (TAHQ), 4, 4'-Phenylenedioxydiphthalic anhydride (HQDA), other suitable tetracarboxylic dianhydride monomers, or any mixture of the above monomers. Accordingly, in the polyamide acid (A2) formed by the second reaction, the long-chain structure of the tetracarboxylic dianhydride monomer (a2) can effectively reduce the dielectric constant and dielectric constant of the polyamide acid (A2) Loss factor, and the rigid monomer diamine monomer (b2) can still maintain the structural rigidity of the polyamide acid (A2) segment.

It should be noted that in the chemical structure of the aforementioned p-phenylbis(trimellitic acid dianhydride) (TAHQ), although it has a longer molecular chain structure, the benzene ring The ester group is connected, so TAHQ can not only improve the structural rigidity of the formed material, it can also reduce the density of the imine functional group of the formed polyimide segment, thereby reducing the dielectric constant and dielectric constant of the material. Electrical loss factor. In other words, p-phenylbis(trimellitate) tetracarboxylic dianhydride (TAHQ) has the functions of the aforementioned rigid monomer and flexible monomer.

In the second reaction, the molar ratio of the tetracarboxylic dianhydride monomer (a2) to the diamine monomer (b2) is preferably 0.95:1 to 1:1. Similarly, the second reaction is performed using the reaction temperature and other reaction parameters that are well known to those with ordinary knowledge in the technical field of the present invention, so no further description is given here. The block polyamic acid prepared by the second reaction is a colloidal solution. The viscosity of the colloidal solution is 1000 cps to 20000 cps, and preferably 3000 cps to 13000 cps.

Based on the prepared polyimide precursor content of 100 mol%, the content of polyamide acid (A2) can be 10 mol% to 60 mol%, preferably 20 mol% to 50 mol% Ear percentage, and more preferably 25 mol% to 40 mol%.

In some embodiments, the order of the aforementioned first reaction and the second reaction can be replaced with each other. In other words, the second reaction is performed first to form polyamide acid (A2), and then the first reaction is performed on polyamide acid (A2), tetracarboxylic dianhydride monomer (a1) and diamine monomer (b1) , To obtain a block polyamide composed of polyamide (A2) and polyamide (A1). It should be noted that in some embodiments, although the order of the first reaction and the second reaction can be changed, the molar content of the polyamide acid (A1) in the block polyamide acid obtained is still Greater than the molar content of polyamide (A2).

After the block polyamide is prepared, the third reaction is performed on the block polyamide, the tetracarboxylic dianhydride monomer (a3) and the diamine monomer (b3) to obtain the block polyamide of the present invention. A polyimide precursor composed of amide acid and the third polyamide acid (A3). Among them, the third polyamide acid (A3) is prepared by reacting tetracarboxylic dianhydride monomer (a3) and diamine monomer (b3).

When performing the third reaction, in order to further reduce the dielectric constant and the dielectric loss factor of the polyimide precursor, the diamine monomer (b3) can be a flexible monomer. In some embodiments, the diamine monomer (b3) may include a diamine monomer with an ether group in the main chain, a diamine monomer with an alkyl group in the side chain, other suitable diamine monomers, or any of the above monomers. Mix arbitrarily. In some specific examples, the diamine monomer (b3) of the flexible monomer can be 1,4-bis(4-aminophenoxy)benzene (TPE-Q), 4,4'-diamino-2,2 '-Dimethyl-1,1'-biphenyl (m-TB-HG), other suitable diamine monomers, or any mixture of the above monomers. Secondly, in order to maintain the rigidity of the polyamide acid (A3) segment, the tetracarboxylic dianhydride monomer (a3) can be a rigid monomer. It is understandable that the type of the tetracarboxylic dianhydride monomer (a3) of the rigid monomer is the same as the aforementioned tetracarboxylic dianhydride monomer (a1), so it will not be repeated here.

In the third reaction, the molar ratio of the tetracarboxylic dianhydride monomer (a3) to the diamine monomer (b3) is preferably 0.98:1 to 1:1. Similarly, the third reaction is performed using the reaction temperature and other reaction parameters well-known to those with ordinary knowledge in the technical field to which the present invention belongs, so it will not be repeated here. The polyimide precursor prepared by the third reaction is a colloidal solution (that is, a polymer solid containing a solvent and a polyimine precursor). The viscosity of the colloidal solution can be 10,000 cps to 50,000 cps, and preferably can be 15,000 to 40,000. In some embodiments, the total solid content of the polyimide precursor may be 10 wt% to 25 wt%, and preferably may be 14 wt% to 20 wt%. When the viscosity and total solid content of the polyimide precursor are within the aforementioned ranges, the prepared polyimide precursor can have better film-forming properties and coating properties, which will help the back-end application requirements .

Based on the prepared polyimide precursor content of 100 mol%, the content of polyamide acid (A3) can be 10 mol% to 30 mol%, and preferably 10 mol% to 25 mol% Percentage of moles.

In the prepared polyamide acid (A3), the tetracarboxylic dianhydride monomer (a3) can provide segment rigidity, and the diamine monomer (b3) can reduce the dielectric of the polyimide precursor Constant and dielectric dissipation factor. Among them, since the imine functional group in the polyimine is mainly formed by the tetracarboxylic dianhydride monomer, compared with the aforementioned tetracarboxylic dianhydride monomer (a2), the diamine monomer (b3 ) Has a greater impact on the flexibility of the polyimide precursor, but the long molecular structure of the tetracarboxylic dianhydride monomer (a2) and diamine monomer (b3) can effectively reduce the polyimide produced The density of the imine functional group can reduce its dielectric constant and dielectric loss factor.

According to this, the flexible segments of polyamide acid (A2) and polyamide acid (A3) (ie tetracarboxylic dianhydride monomer (a2) and diamine monomer ( b3) derivative group), and the rigid segment of polyamide acid (A1), polyamide acid (A2) and polyamide acid (A3) (ie diamine monomer (b2) and tetracarboxylic acid The derivative group of dianhydride monomer (a3)), the polyimide film prepared from the polyimide precursor of the present invention can have good dimensional stability and better electrical performance. Therefore, when the contents of polyimide (A1), polyimide (A2) and polyimide (A3) are in the aforementioned ranges, respectively, the polyimide precursor can have good dimensional stability and relatively good dimensional stability. Excellent high frequency transmission performance.

After performing the third reaction, the obtained polyimine precursor is subjected to a solvent removal step to obtain the polymer solid of the polyimine precursor. Then, the solid polyimide precursor is further heated to obtain polyimide. It is understandable that when the polyimide precursor is coated to form a film, the The solid polyimide precursor prepared in the reagent step is the polyimide film, and after further heating, the polyimide film can be prepared. In some specific examples, the thickness of the polyimide film may be 5 μm to 100 μm.

Accordingly, the polyimide precursor of the present invention can be coated on copper foil or other substrates, and then the aforementioned solvent removal step and heating step can be used to prepare a copper foil substrate with a polyimide film . Then, after etching the copper foil into the required pattern, a flexible conductive substrate can be prepared.

According to the above description, the polyimide precursor in this case is composed of polyimide (A1) with main rigid segment, polyimide (A2) with low dielectric loss segment and low dielectric loss It is composed of polyamide acid (A3) with flexible segment. Therefore, the prepared polyimide precursor is a regular block copolymer, and has low charge transfer resistance. In some application examples, the dielectric loss factor of the prepared polyimide can be 0.003 to 0.005, and the dielectric constant can be 3.0 to 3.7. In some examples, the dielectric loss factor of polyimide may be preferably 0.003 to 0.005, and more preferably 0.003 to 0.004. In some examples, the dielectric constant of polyimide may preferably be 3.0 to 3.5.

The following examples are used to illustrate the application of the present invention, but they are not intended to limit the present invention. Anyone who is familiar with the art can make various changes and modifications without departing from the spirit and scope of the present invention.

Preparation of polyimide film Example 1

First, 0.015 mol of 4,4'-diaminobenzidine (DABA) is added to N-methylpyrrolidone (NMP) to form the diamine monomer Solution. Then, 0.015 mol of pyromellitic dianhydride (PMDA) was added to carry out the first stage reaction. After 1 to 4 hours, a colloidal solution (with a viscosity of 40 cps) containing polyamide acid (A1) can be prepared.

Next, add 0.075 mol of p-phenylenediamine (p-PDA) and 0.075 mol of p-phenylbis(trimellitic acid ester) ditetracarboxylic dianhydride (TAHQ) to contain polyamide acid ( A1) in the colloidal solution for the second stage reaction. After 1 to 4 hours, a colloidal solution containing block polyamide (viscosity 19500cps) can be prepared.

Then, add 0.010 mol of 1,4-bis(4-aminophenoxy)benzene (TPE-Q) and 0.010 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s- BPDA) into the colloidal solution containing the block polyamide acid for the third stage reaction. After 1 to 4 hours, a colloidal solution (viscosity of 32900 cps) containing the polyimide precursor can be prepared. Based on the prepared polyimide precursor content of 100 mol%, the content of polyamide acid (A1) is 15 mol%, the content of polyamide acid (A2) is 75 mol%, and The content of amide acid (A3) is 10 mole percent.

The colloidal solution containing the polyimide precursor is coated to form a film, and the solvent is removed to form a solid polyimide precursor film. Then, the polyimide precursor film is further heated to perform the imidization reaction, and the polyimide film of Example 1 can be prepared. The obtained polyimide film was evaluated by the following evaluation methods of dielectric constant and dielectric loss factor, and the results are shown in Table 1, which will not be repeated here.

Example 2

The polyimide film of Example 2 uses the same process steps as the production method of the polyimide film of Example 1, except that Examples 2 to 3 use different types and usage amounts of tetracarboxylic acid. Acid dianhydride monomer and diamine monomer. The formula and evaluation results are shown in Table 1.

Comparative example 1

First, mix 0.025 mol of 4,4'-diaminobenzylaniline (DABA), 0.015 mol of 1,4-bis(4-aminophenoxy)benzene (TPE-Q) and 0.06 mol of 1,4-bis(4-aminophenoxy)benzene (TPE-Q). P-phenylenediamine (p-PDA) is added to N-methylpyrrolidone to form a diamine monomer solution. Then, 0.025 mol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) and 0.075 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride ( s-BPDA) was added to the diamine monomer solution for polymerization. After 1 to 4 hours, a colloidal solution containing polyimine precursor can be obtained.

Then, the colloidal solution containing the polyimide precursor is coated to form a film, and the solvent is removed to form a solid polyimide precursor film. Then, the polyimide precursor film is further heated to perform the imidization reaction, and the polyimide film of Comparative Example 1 can be prepared. The obtained polyimide film was evaluated by the following evaluation methods of dielectric constant and dielectric loss factor, and the results are shown in Table 1, which will not be repeated here.

Comparative example 2

The polyimide film of Comparative Example 2 uses the same process steps as the preparation method of the polyimide film of Comparative Example 1, except that the diamine monomer used in Comparative Example 2 is a 0.075 mol pair -Phenylenediamine (p-PDA) and 0.025 mol of 1,4-bis(4-aminophenoxy)benzene (TPE-Q), and tetracarboxylic acid The acid dianhydride monomer is 0.10 mol of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA). The formula and the evaluation results of the polyimide film are shown in Table 1. Shown.

Comparative example 3 and comparative example 4

The polyimide film of Comparative Example 3 and Comparative Example 4 uses the same process steps as the production method of the polyimide film of Example 1, except that Comparative Example 3 and Comparative Example 4 use different types and uses The amount of tetracarboxylic dianhydride monomer and diamine monomer. The formula and evaluation results are shown in Table 1.

Dielectric constant and dielectric loss factor

First, wipe the polyimide film prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 4 with alcohol, and then place the polyimide film in an oven at 150°C. After being baked for 30 minutes, it is placed in a room temperature environment (temperature is 21°C to 25°C, and relative humidity is 45% to 55%). After 24 hours, a network analyzer (manufactured by ROHDE & SCHWARZ and model ZNB-20) was used to measure the dielectric constant and dielectric loss factor of the polyimide film.

In Table 1, PMDA representative of pyromellitic dianhydride (Pyromellitic dianhydride); DABA representative of 4,4'-diamino benzoyl aniline (4,4 '-diaminobenzanilide): p- PDA representative - phenylenediamine (1,4-phenylenediamine); TPE-Q stands for 1,4-bis(4-aminophenoxy)benzene (1,4-bis(4-aminophenoxy)benzene); m-TB-HG stands for 4,4'-Diamino-2,2'-dimethyl-1,1'-biphenyl(2,2'-dimethylbenzidine); BTDA stands for 3,3',4,4'-benzophenonetetracarboxylic dianhydride ( 3,3',4,4'-benzophenonetetracarboxylic dianhydride); s-BPDA stands for 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3 ' ,4,4 ' -biphenyltetracarboxylic dianhydride); TAHQ Represents p-phenylene bis(trimellitate)dianhydride; HQDA represents 4,4'-terephthalic acid anhydride (1, 4-Bis(3,4-dicarboxyphenoxy)benzene dianhydride).

According to the content in Table 1, the polyimide film prepared in Examples 1 to 3 can have a lower dielectric loss factor (Df ) And dielectric constant (Dk). Among them, when the long molecular chain polyamide acid (resulting from the reaction of rigid diamine monomer and rigid tetracarboxylic dianhydride monomer) has the largest content, the prepared polyimide film (that is, the implementation Example 2) has a lower dielectric loss factor and dielectric constant.

In Comparative Example 1 and Comparative Example 2, when the polyimide precursor is not formed by the stepwise reaction as described in this case, the obtained polyimide film has poor electrical performance. In Comparative Example 3, although the polyimide precursor was prepared by a two-stage reaction, the prepared polyimide precursor lacks the polyimide (A2) as described in this case, so The prepared polyimide film still has poor electrical performance.

Accordingly, the preparation method of the polyimide precursor of the present invention is to form a regularly arranged block copolymer by reacting in stages and selecting specific tetracarboxylic dianhydride monomers and diamine monomers, and It can reduce the dielectric loss, thereby reducing the energy loss of the subsequent copper foil circuit. Among them, the polyimide precursor is composed of polyamide acid (A1) with a main rigid segment, polyamide acid (A2) with a low dielectric loss segment, and a polyamide with a low dielectric loss and flexible segment. It is composed of amide acid (A3). Therefore, the formed polyimide has good dimensional stability, low dielectric constant and dielectric loss factor, and can reduce the signal loss of signal transmission, so it can meet the application requirements of high-frequency transmission.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, therefore, the scope of protection of the present invention shall be subject to the scope of the attached patent application.

Claims (9)

A preparation method of a polyimide precursor, comprising: Performing a first reaction on a first tetracarboxylic dianhydride monomer and a first diamine monomer to form a first polyamide acid; A second reaction is performed on the first polyamide acid, a second tetracarboxylic dianhydride monomer, and a second diamine monomer to form a block polyamide acid, wherein the block polyamide The acid is composed of the first polyamide and a second polyamide, and the second polyamide is composed of the second tetracarboxylic dianhydride monomer and the second diamine monomer. Formed; and A third reaction is performed on the block polyamide acid, a third tetracarboxylic dianhydride monomer, and a third diamine monomer to form the polyimide precursor, wherein the polyimide precursor The material system is composed of the block polyamide and a third polyamide, and the third polyamide is composed of the third tetracarboxylic dianhydride monomer and the third diamine monomer. Formed, and Wherein one of the first tetracarboxylic dianhydride monomer or the second tetracarboxylic dianhydride monomer is a tetracarboxylic dianhydride monomer having an ether group in the main chain; and The third diamine monomer has a diamine monomer having an ether group in the main chain or a diamine monomer having an alkyl group in the side chain. As described in the first item of the scope of patent application, the preparation method of the polyimide precursor, wherein based on the content of one of the polyimine precursors is 100 mole percent, the content of one of the third polyimine is 10%. Mole percent to 30 mole percent. The method for preparing polyimine precursor as described in item 2 of the scope of patent application, wherein based on the content of the polyimine precursor being 100 mole percent, the first tetracarboxylic dianhydride monomer or the The content of one of the first polyamide or the second polyamide formed by the one of the second tetracarboxylic dianhydride monomer is 10 mol% to 60 mol%. The method for preparing the polyimine precursor as described in item 3 of the scope of the patent application, wherein based on the content of the polyimine precursor being 100 mole percent, the first tetracarboxylic dianhydride monomer or the The content of one of the first polyamide or the second polyamide formed by the other of the second tetracarboxylic dianhydride monomers is 20 mol% to 75 mol%. The method for preparing the polyimide precursor as described in item 1 of the scope of patent application, wherein the first diamine monomer and the second diamine monomer are not diamine monomers with ether groups in the main chain or side diamine monomers. A diamine monomer with an alkyl group in the chain. According to the method for preparing the polyimide precursor described in item 1 of the scope of the patent application, the third tetracarboxylic dianhydride monomer is not a tetracarboxylic dianhydride monomer having an ether group in the main chain. According to the manufacturing method of the polyimine precursor described in item 1 of the scope of patent application, the total solid content of one of the polyimine precursors is 10 weight percent to 25 weight percent. A polyimide formed by heating a polyimine precursor, and the polyimine precursor is prepared by the manufacturing method described in any one of items 1 to 7 in the scope of the patent application Thus, each molecular chain of the polyimide is composed of a first polyamide, a second polyamide, and a third polyamide. The polyimide described in item 8 of the scope of patent application, wherein the polyimide has a dielectric loss factor of 0.003 to 0.005 and a dielectric constant of 3.0 to 3.7.