TWI892749B - Heat-resistant liquid crystal polymer film - Google Patents

Abstract

The heat-resistant liquid crystal polymer film of the present invention includes a soluble liquid crystal polymer, which accounts for 15-75wt% of the heat-resistant liquid crystal polymer film; an insoluble liquid crystal polymer, which accounts for 15-75wt% of the heat-resistant liquid crystal polymer film; and a polyimide, which is composed of dianhydride and diamine, which accounts for 10-50wt% of the heat-resistant liquid crystal polymer film, and the glass transition temperature (Tg) of the polyimide is greater than 250°C, wherein the moisture absorption of the heat-resistant liquid crystal polymer film is less than The heat-resistant liquid crystal polymer film has a dielectric loss (Df) of less than 0.005 at a frequency of 10 GHz and a humidity of 65% RH. Furthermore, the heat-resistant liquid crystal polymer film has a coefficient of linear thermal expansion (CTE) of less than 20 ppm/°C at a temperature of 50-200°C. At a temperature of 310°C, the heat-resistant liquid crystal polymer film has a storage modulus (E') greater than 0.2 GPa. The heat-resistant liquid crystal polymer film has a glass transition temperature (Tg) greater than 220°C.

Description

Heat-resistant liquid crystal polymer film

The present invention relates to a heat-resistant liquid crystal polymer film, particularly one that exhibits good dielectric properties, excellent temperature resistance, and a low expansion coefficient under high moisture absorption conditions, and can be applied in high-frequency and high-speed transmission fields.

Taiwan Patent No. I786659 discloses a composite film comprising a soluble liquid crystal polymer, an insoluble liquid crystal polymer, and polyimide. By using a relatively low ratio of polyimide, the composite film exhibits excellent dielectric properties and operability in basic FCCL and FPC back-end processes. However, the excellent heat resistance and mechanical properties primarily derive from the polyimide and the high polyimide ratio. Furthermore, the polyimide used is primarily ester-containing, which has poor heat resistance. These factors limit further optimization of this composite film, making it difficult to simultaneously achieve superior dielectric properties and heat resistance.

The present invention is a heat-resistant liquid crystal polymer film, which includes a soluble liquid crystal polymer, which accounts for 15-75wt% of the heat-resistant liquid crystal polymer film; an insoluble liquid crystal polymer, which accounts for 15-75wt% of the heat-resistant liquid crystal polymer film; and a polyimide, which is composed of dianhydride and diamine, which accounts for 10-50wt% of the heat-resistant liquid crystal polymer film, and the glass transition temperature (Tg) of the polyimide is greater than 250°C. The heat-resistant liquid crystal polymer film has a moisture absorption of less than 0.5%, a dielectric loss (Df) of less than 0.005 at a frequency of 10 GHz and a humidity of 65% RH, a linear thermal expansion coefficient (CTE) of less than 20 ppm/°C at 50-200°C, a storage modulus (E') greater than 0.2 GPa at 310°C, and a glass transition temperature (Tg) greater than 220°C.

The present invention is a heat-resistant liquid crystal polymer film comprising a soluble liquid crystal polymer, an insoluble liquid crystal polymer, and a polyimide.

Soluble liquid crystal polymers are soluble in organic solvents, which may be at least one of the group consisting of dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL), and N,N-dimethylformamide (DMF). Their solubility is 5 wt% or more, preferably 8% or more, and even more preferably 10% or more.

The soluble liquid crystal polymer accounts for 15-75 wt% of the heat-resistant liquid crystal polymer film.

The insoluble liquid crystal polymer accounts for 15-75 wt% of the heat-resistant liquid crystal polymer film.

Insoluble liquid crystal polymer having a dielectric loss (Df) less than 0.001, preferably less than 0.0009, and more preferably less than 0.0008.

The insoluble liquid crystal polymer is in the form of a powder with a 50% cumulative particle size distribution (D50) of less than 20 μm and a 99% cumulative particle size distribution (D99) of less than 2.5 times the D50.

The insoluble liquid crystal polymer is in the form of a powder with a water absorption rate of less than 0.5%, preferably less than 0.05%.

The polyimide accounts for 10-50% by weight of the total heat-resistant liquid crystal polymer film. The polyimide preferably has a glass transition temperature (Tg) greater than 250°C, more preferably greater than 300°C.

The heat-resistant liquid crystal polymer film has the following properties: hygroscopicity less than 0.5%; dielectric dissipation (Df) less than 0.005 at a frequency of 10 kHz and a humidity of 65% RH; coefficient of linear thermal expansion (CTE) less than 20 ppm/°C from 50°C to 200°C; storage modulus (E') greater than 0.2 GPa at 310°C; and glass transition temperature (Tg) greater than 220°C.

The monomers of the polyimide include pyromellitic dianhydride, which accounts for 20-80% of the total.

In addition, other dianhydrides such as 3,3',4,4'-biphenyltetracarboxylic dianhydride, p-phenylene-bis(triphenyl)phthalate dianhydride, and 4,4'-oxydiphthalic anhydride may be added as needed.

The diamine component monomers of the polyimide include p-phenylenediamine, which accounts for 40-60% of the total diamines. More preferably, p-phenylenediamine and combinations thereof with the following diamines are included, for example, 1,3-bis(4'-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis(3-aminophenoxy)benzene, p-aminophenyl para-benzoate, 2,2'-bis(trifluoromethyl)diaminobiphenyl, and 4,4'-diaminodiphenyl ether.

Next, the soluble liquid crystal polymer (LCP), insoluble liquid crystal polymer (LCP), and polyamide are mixed and appropriately diluted. A curing catalyst is added, and after centrifugal degassing, the coating is applied to glass or other metal substrates. The coating is then baked at 60-80°C for 40-120 minutes to form a gel film. The gel film is then removed from the substrate and fixed to a metal frame, where it is baked at 300°C for 60 minutes to form the film. The optimal baking temperature is 300°C, and more preferably above 320°C.

The heat-resistant liquid crystal polymer film of the present invention is hardened by chemical catalysis. The catalyst can be pyridine, 3-picoline, 2-picoline, 4-picoline, isoquinoline, quinoline, and triethylamine, with pyridine, 3-picoline, 2-picoline, and 4-picoline being preferred. In the present invention, 3-picoline can be used as the catalyst, and acetic anhydride can be used as the dehydrating agent.

The heat-resistant liquid crystal polymer film of the present invention can also incorporate other types of inorganic or organic fillers depending on its functional requirements. Organic fillers, such as fluoropolymers, such as polytetrafluoroethylene (PTFE) and copolymers of tetrafluoroethylene and perfluoroalkyl vinyl ether (PFA), can be used to reduce the dielectric constant. Furthermore, antistatic properties and temperature resistance can be enhanced by adding phospholipid-containing organic polymers, or fillers such as silica and aluminum oxide. Furthermore, fillers containing alkene structures or silanes can be added to improve surface adhesion.

The present invention can be applied to flexible circuit substrates, including insulating materials and cover films, with insulating materials being particularly preferred. For example, it can be applied to metal laminates, which include at least one laminate and a heat-resistant liquid crystal polymer film. Alternatively, the metal laminate may include a metal layer, the heat-resistant liquid crystal polymer film of the present invention, and a bonding layer between the metal layer and the heat-resistant liquid crystal polymer film.

The metal layer material is not particularly limited. Single metals such as copper, nickel, aluminum, and silver, or alloys of these metals can be used, with copper being the most preferred.

The present invention is described below in detail based on the following examples, but the present invention is not limited thereto. Furthermore, the details of the raw materials represented by abbreviations in each example are presented below.

Monomers that make up polyimide:

3,3’,4,4’-Biphenyltetracarboxylic acid dibasic: BPDA

Pyromellitic Dianhydride: PMDA

Paraphenylenediamine: PDA

1,3-Bis(4'-aminophenoxy)benzene: TPER

2,2'-Bis(trifluoromethyl)diaminobenzidine: TFMB

4,4'-Diaminodiphenyl ether: 4,4'ODA or ODA

4,4'-Diaminodiphenyl ether: 34ODA

2,2'-Dimethyl-4,4'-diaminobenzidine: m-TB

Insoluble Liquid Crystal Polymers (LCPs): LF-31P liquid crystal polymer powder, developed and manufactured by ENEOS.

Soluble liquid crystal polymer (LCPv): liquid crystal polymer slurry.

Solvent

DMAc: dimethylacetamide

AA: Acetic anhydride

AP: 3-methylpyridine

Detection method

The various properties of the heat-resistant liquid crystal polymer films obtained in the following examples were measured using the following methods.

Humidity conditions: Results displayed using a digital hygrometer (model DTM-301H) manufactured by TECPEL.

Dielectric loss: Measured in accordance with ASTM D2520 using an Agilent E5071C network analyzer, distributed by VeriTech. Measurements were performed at a relative humidity of 65% or 100% RH and a frequency of 10 GHz. Three measurements were taken, and the average value was used as the actual value.

Coefficient of linear expansion (50-200°C): Measured in accordance with ASTM D696 using a TA Instruments Q400 TMA. The measurement temperature range was 50-200°C, with a heating rate of 10°C/min. The first measurement was performed to eliminate any residual film stress, and the second measurement was used as the experimental result.

Storage modulus (E'): Measured using a Metravib DMA25 instrument at 310°C. The remaining measurement conditions are as follows:

Sample measurement range: width 15mm, clamp spacing 20mm

Temperature setting range: 30~400℃

Heating rate: 10°C/min

Dynamic force: 100mN

Static force: 1N

Frequency: 5Hz

Glass transition temperature (Tg): Measured using a DMA25 instrument manufactured by Metravib, using the same measurement conditions as those used for the storage elastic modulus. The temperature corresponding to the peak of the loss tangent is defined as the glass transition temperature.

[Example 1]

1.4g of PDA and 3.1g of TPER were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 1.8g of PMDA and 4.5g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Next, 15.0g of the polyimide precursor, 15.4g of soluble liquid crystal molecules with a 10% solids content, and 3.5g of insoluble liquid crystal polymer were mixed and stirred. A catalyst and dehydrating agent mixture consisting of 2.4g of AA and 2.2g of AP was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive composition was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The coating was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to complete the process.

[Example 2]

To polymerize 60g of polyimide precursor, add 1.1g of PDA and 3.6g of TPER to 49.2g of DMAc solvent and stir until dissolved. Then, add 1.2g of PMDA and 4.9g of BPDA. The reaction temperature is controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA is used to fine-tune the viscosity. The final product is 60g of polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Next, 15.0g of the polyimide precursor, 15.4g of soluble liquid crystal molecules with a 10% solids content, and 3.5g of insoluble liquid crystal polymer are mixed and stirred. A catalyst and dehydrating agent mixture consisting of 2.3g of AA and 2.1g of AP was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. After uniform mixing, the mixture was centrifuged for degassing, applied to a substrate, and baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to form a gel composite film.

[Example 3]

0.94g of PDA, 1.3g of TPER, and 2.8g of TFMB were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 1.7g of PMDA and 4.2g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. 15.0g of the polyimide precursor, 15.4g of 10% solids content, 14.5g of soluble liquid crystal molecules, and 3.5g of insoluble liquid crystal polymer were mixed and stirred. A mixture of a catalyst and a dehydrating agent, consisting of 2.2g of AA and 2.0g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate and fixed to a metal frame. The film was then baked at 300°C for 60 minutes to form the film.

[Example 4]

1.6g of PDA, 1.5g of TPER, and 1.0g of 34ODA were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 1.9g of PMDA and 4.8g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. 15.0g of the polyimide precursor, 15.4g of soluble liquid crystal molecules with a 10% solids content, and 3.5g of insoluble liquid crystal polymer were mixed and stirred. A mixture of a catalyst and a dehydrating agent, consisting of 2.6g of AA and 2.3g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive composition was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The resulting gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate and fixed to a metal frame, then baked at 300°C for 60 minutes to form a film.

[Example 5]

0.94g of PDA, 1.3g of TPER, and 2.8g of TFMB were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 1.7g of PMDA and 4.2g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. 15.0g of the polyimide precursor, 27g of a soluble liquid crystal slurry with a 10% solids content, and 1.4g of an insoluble liquid crystal polymer powder were mixed and stirred until uniformly dissolved. A catalyst and dehydrating agent mixture consisting of 2.2g of AA and 2.0g of AP was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive mixture was then evenly mixed, defoamed by centrifugation, and applied to a substrate. The resulting gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to complete the process.

[Example 6]

0.94g of PDA, 1.3g of TPER, and 2.8g of TFMB were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 1.7g of PMDA and 4.2g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPADA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. To this 15.0g polyimide precursor, 22.5g of soluble liquid crystal molecules with a 10% solids content and 10.1g of insoluble liquid crystal polymer were mixed and stirred. A mixture of a catalyst and a dehydrating agent, consisting of 2.2g of AA and 2.0g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive was evenly mixed, defoamed by centrifugation, applied to a substrate, and baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was then removed from the substrate and fixed to a metal frame, where it was further baked at 300°C for 60 minutes to complete the process.

【Comparative Example 1】

Add 1.4g of PDA and 3.0g of TPER to 49.2g of DMAc solvent and stir until dissolved. Then add 0.75g of PMDA and 5.7g of BPDA. Control the reaction temperature at 25°C and continue stirring for 2-3 hours. Use a small amount of BPDA to fine-tune the viscosity. The final product is 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Then, mix 15.0g of the polyimide precursor, 15.4g of a soluble liquid crystal slurry with a 10% solids content, and 3.5g of an insoluble liquid crystal polymer powder and stir thoroughly. A mixture of a catalyst and a dehydrating agent, consisting of 2.3g of AA and 2.1g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate and fixed to a metal frame. The film was then baked at 300°C for 60 minutes to complete the process.

【Comparative Example 2】

1.5g of PDA, 2.4g of TPER, and 0.83g of m-TB were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 4.7g of PMDA and 1.4g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. 15.0g of the polyimide precursor, 15.4g of a soluble liquid crystal slurry with a 10% solids content, and 3.5g of an insoluble liquid crystal polymer powder were mixed and stirred. A mixture of a catalyst and a dehydrating agent, consisting of 2.3g of AA and 2.1g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The gel composite film was then baked at 60-80°C for 120-40 minutes to form a gel composite film. The gel composite film was removed from the substrate and fixed to a metal frame, where it was then baked at 300°C for 60 minutes to complete the process.

【Comparative Example 3】

Add 1.7g of PDA and 2.5g of TPER to 49.2g of DMAc solvent and stir until dissolved. Then add 1.9g of PMDA and 4.7g of BPDA. Keep the reaction temperature at 25°C and stir for 2-3 hours. Use a small amount of BPADA to fine-tune the viscosity. The final product is 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Then, mix 15.0g of the polyimide precursor, 15.4g of a soluble liquid crystal slurry with a 10% solids content, and 3.5g of an insoluble liquid crystal polymer powder and stir until uniform. A mixture of a catalyst and a dehydrating agent, consisting of 2.3g of AA and 2.1g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive composition was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The gel composite film was then baked at 60-80°C for 40-1200 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to form a film.

【Comparative Example 4】

0.64g of PDA, 3.4g of TPER, and 0.88g of ODA were added to 49.2g of DMAc solvent and stirred until dissolved. Then, 1.7g of PMDA and 4.2g of BPDA were added. The reaction temperature was controlled at 25°C and stirred for 2-3 hours. A small amount of BPDA was used to fine-tune the viscosity. The final product was 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. 15.0g of the polyimide precursor, 15.4g of a soluble liquid crystal slurry with a 10% solids content, and 3.5g of an insoluble liquid crystal polymer powder were mixed and stirred. A mixture of a catalyst and a dehydrating agent, consisting of 2.2g of AA and 2.1g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive composition was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to complete the process.

【Comparative Example 5】

Add 1.1g of PDA and 3.6g of TPER to 49.2g of DMAc solvent and stir until dissolved. Then add 1.2g of PMDA and 4.9g of BPDA. Control the reaction temperature at 25°C and continue stirring for 2-3 hours. Use a small amount of BPDA to fine-tune the viscosity. The final product is 60g of a polyimide precursor with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Then, mix 15.0g of the polyimide precursor, 32.4g of a soluble liquid crystal slurry with a 10% solids content, and 21.1g of an insoluble liquid crystal polymer powder and stir until uniformly dissolved. A mixture of a catalyst and a dehydrating agent, consisting of 2.3g of AA and 2.1g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to complete the process.

【Comparative Example 6】

Add 1.1g of PDA and 3.6g of TPER to 49.2g of DMAc solvent and stir until dissolved. Then add 1.2g of PMDA and 4.9g of BPDA. Control the reaction temperature at 25°C and continue stirring for 2-3 hours. Use a small amount of BPDA to fine-tune the viscosity. The final product is 60g of a polyimide pre-driver with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Then, mix 15.0g of the polyimide pre-driver, 3.6g of a soluble liquid crystal slurry with a 10% solids content, and 0.54g of an insoluble liquid crystal polymer powder and stir until uniformly dissolved. A mixture of a catalyst and a dehydrating agent, consisting of 2.3g of AA and 2.1g of AP, was added to the mixed solution, resulting in an adhesive composition with a total solids content of 20%. The adhesive composition was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The resulting gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was then removed from the substrate, fixed to a metal frame, and baked at 300°C for 60 minutes to complete the process.

【Comparative Example 7】

Add 1.1g of PDA and 3.6g of TPER to 49.2g of DMAc solvent and stir until dissolved. Then, add 1.2g of PMDA and 4.9g of BPDA. Control the reaction temperature at 25°C and continue stirring for 2-3 hours. Use a small amount of BPADA to fine-tune the viscosity. The final product is 60g of a polyimide pre-driver with an 18.0% solids content and a viscosity of 160,000 ± 40,000 cps. Then, mix 15g of the polyimide pre-driver, 93.2g of a soluble liquid crystal slurry with a 20% solids content, and 3.2g of an insoluble liquid crystal polymer powder and stir until uniformly dissolved. A mixture of a catalyst and a dehydrating agent was added to the mixed solution. The mixture consisted of 2.3g of AA and 2.1g of AP, resulting in an adhesive composition with a total solids content of 20%. The adhesive composition was evenly mixed, defoamed by centrifugation, and then applied to a substrate. The resulting gel composite film was then baked at 60-80°C for 40-120 minutes to form a gel composite film. The gel composite film was removed from the substrate, fixed to a metal frame, and then baked at 300°C for 60 minutes to form a film.

Table 1: Composition of polyimide ingredients used

Table 2: Composition and properties of high-temperature resistant liquid crystal polymer molds

Regarding Examples 1-6: Because Examples 1-6 utilize specific polyimide, soluble liquid crystal polymer, and insoluble liquid crystal polymer in specific ratios, the composite films produced in these Examples exhibit the desired moisture absorption, dielectric loss (Df), coefficient of linear thermal expansion (CTE), storage modulus (E'), and glass transition temperature (Tg) of the present invention, meeting the requirements of the present invention.

Regarding Comparative Example 1: Because the content of pyromellitic dianhydride relative to the total dianhydrides in its polyimide composition B1 is less than 20 mol%, the resulting heat-resistant liquid crystal polymer has a coefficient of linear expansion (CTE) greater than 20, a glass transition temperature (Tg) less than 220°C, and a storage modulus (E') at 310°C less than 0.2, which does not meet the requirements of the present invention.

Regarding Comparative Example 2: Because the content of pyromellitic dianhydride (PMDA) in polyimide composition B2 relative to the total dianhydrides is greater than 80 mol%, the resulting heat-resistant liquid crystal polymer film exhibits a dielectric loss greater than 0.005 and a water absorption greater than 0.5% at 100% RH, failing to meet the requirements of the present invention.

Regarding Comparative Example 3: Because the content of p-phenylenediamine (PDA) relative to the total diamine content in polyimide composition B3 is greater than 60 mol%, the resulting heat-resistant liquid crystal polymer film exhibits a dielectric loss greater than 0.005 at 100% RH and a water absorption greater than 0.5%, failing to meet the requirements of the present invention.

Regarding Comparative Example 4: Because the content of p-phenylenediamine (PDA) relative to the total diamine content in polyimide composition B4 is less than 40 mol%, the resulting heat-resistant liquid crystal polymer film has a linear expansion coefficient greater than 20 and a glass transition temperature less than 220°C, which does not meet the requirements of the present invention.

Regarding Comparative Example 5: Because the insoluble liquid crystal polymer accounts for more than 75% of the total liquid crystal polymer film, the heat-resistant liquid crystal polymer film produced has a storage modulus of less than 0.2 at 310°C.

Regarding Comparative Example 6: Because polyimide accounts for more than 50 wt% of the total liquid crystal polymer film, the resulting liquid crystal polymer film has a dielectric loss greater than 0.005 at 100% RH and a water absorption greater than 0.5%, which does not meet the requirements of the present invention.

Regarding Comparative Example 7: Because the soluble liquid crystal polymer (LCP) in the total LC polymer film accounts for greater than 75% by weight, the resulting heat-resistant LC polymer film exhibits a linear expansion coefficient greater than 20, a storage modulus at 310°C less than 0.2, a water absorption greater than 0.5%, and a glass transition temperature less than 220°C, which do not meet the requirements of the present invention.

The above specific embodiments are provided to illustrate the present invention in detail. However, these embodiments are for illustrative purposes only and are not intended to limit the present invention. Those skilled in the art will appreciate that various variations and modifications made to the present invention without departing from the scope of the appended patent applications are considered to be part of the present invention.

Claims (4)

A heat-resistant liquid crystal polymer film comprises: a soluble liquid crystal polymer, which accounts for 15-75 wt% of the heat-resistant liquid crystal polymer film; an insoluble liquid crystal polymer, which accounts for 15-75 wt% of the heat-resistant liquid crystal polymer film; and a polyimide, which is composed of dianhydride and diamine, which accounts for 10-50 wt% of the heat-resistant liquid crystal polymer film, and the glass transition temperature (Tg) of the polyimide is greater than 250°C, the dianhydride includes pyromellitic dianhydride (PMDA), and the diamine includes p-phenylenediamine (PDA), wherein the pyromellitic dianhydride (PMDA) is 20% of the total dianhydride. ~80 mol%, the p-phenylenediamine (PDA) content relative to the total diamine content is 40-60 mol%. The heat-resistant liquid crystal polymer film has a hygroscopicity of less than 0.5%, and at a frequency of 10 GHz and a humidity of 65% RH, the dielectric dissipation (Df) of the heat-resistant liquid crystal polymer film is less than 0.005. Furthermore, at a temperature of 50-200°C, the coefficient of linear thermal expansion (CTE) of the heat-resistant liquid crystal polymer film is less than 20 ppm/°C. At a temperature of 310°C, the storage modulus (E') of the heat-resistant liquid crystal polymer film is greater than 0.2 GPa, and the glass transition temperature (Tg) of the heat-resistant liquid crystal polymer film is greater than 220°C. The heat-resistant liquid crystal polymer film described in item 1 of the patent application, wherein the polyimide accounts for 10-40 wt% of the heat-resistant liquid crystal polymer film, and the dielectric loss (Df) of the heat-resistant liquid crystal polymer film is less than 0.0050 at a frequency of 10 GHz and a humidity of 100%. As described in item 1 of the patent application, the heat-resistant liquid crystal polymer film, wherein the dianhydride further comprises 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA). The heat-resistant liquid crystal polymer film as described in claim 1, wherein the diamine comprises at least one member selected from the group consisting of 1,3-bis(4'-aminophenoxy)benzene (TPER), 1,4-bis(4-aminophenoxy)benzene (TPEQ), 2,2'-bis[4-(4-aminophenoxyphenyl)]propane (BAPP), 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), 1,3-bis(3-aminophenoxy)benzene (APBN), p-aminophenyl para-benzoate (APAB), 2,2'-bis(trifluoromethyl)diaminobenzene (TFMB), and 4,4'-diaminodiphenyl ether (4,4'-ODA).