An alloy film for a flexible circuit board and a method of manufacturing and use thereof

Abstract

The application belongs to the field of high polymer materials, and particularly relates to an alloy film for a flexible circuit board and a preparation method and application thereof, which comprises the following components in parts by weight: polyphenyl ether 10-89.5%; liquid crystal polymer 10-89.5%; reaction catalyst 0.1-5%; antioxidant 0.1-0.3%; and the polyphenyl ether and the liquid crystal polymer generate a polymer alloy under the action of the reaction catalyst. Compared with the prior art, the application solves the defects that pure LCP film is difficult to prepare and process, and pure polyphenyl ether film is difficult to process and has poor solvent resistance, leading to the inability to realize practical application, by jointly forming an alloy film through the reaction of LCP and polyphenyl ether, so that low dielectric constant and low dielectric loss are realized, and the alloy film also meets the processing characteristics of a flexible copper-clad plate material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and particularly relates to an alloy film for a flexible circuit board and a preparation method and application thereof. BACKGROUND

[0002] With the continuous improvement of chip computing performance, high-speed signal transmission requires circuit boards to have lower delay. According to the law of physics, the energy loss of signal transmission in the material increases with the increase of frequency. At present, the 4G communication frequency is still lower than 3GHz, China has opened the new frequency band 3.3-3.6GHz and 4.8-5GHz for 5G application, and the future 5G technology promotes millimeter wave technology, which will face the signal transmission of more than 30GHz, and the transmission loss will be much higher than the current 4G frequency band, so the corresponding radio frequency connecting line and antenna soft board will face performance challenges. The connotation of the demand for high-frequency high-speed circuit is the speed and quality of signal transmission, and the main factors affecting these two are the electrical properties of the transmission material, including the dielectric constant and dielectric loss. Specifically, the speed of signal transmission is negatively related to the dielectric constant, and the quality of signal is negatively related to the dielectric loss.

[0003] At present, 5G communication has begun to use modified polyimide or industrial liquid crystal polymer materials in the market. With the vigorous development of mobile communication technology in recent years, the communication frequency is constantly improving, and the requirements of communication speed and capacity are also getting higher and higher. On the other hand, the space of mobile phone is constantly compressed, and the design space of antenna is gradually reduced, but the traditional terminal device antenna based on PI (polyimide) cannot meet these new demands. Compared with PI, LCP has lower transmission loss, better dimensional stability and bendability.

[0004] Liquid crystal polymer (LCP) has excellent thermal stability, heat resistance and chemical resistance, good weather resistance, radiation resistance, excellent flame resistance, can extinguish the flame and not continue to burn, its combustion rating reaches UL94 V-0 level. LCP has excellent electrical insulation performance, its dielectric strength is higher than that of general engineering plastics, and it has good arc resistance, and its electrical performance is not affected at a continuous use temperature of 200-300 DEG C. The intermittent use temperature can reach about 316 DEG C. LCP also has outstanding corrosion resistance, and LCP products will not be eroded in the presence of 90% acid and 50% alkali, and will not be dissolved or cause stress cracking after contacting industrial solvents, fuel oil, detergents and hot water. LCP plastic raw materials have high strength, high rigidity, high temperature resistance, electrical insulation and other excellent properties, and are used in electronic and electrical fields. However, due to the high requirements of surface assembly welding technology of electronics and electrical appliances on the dimensional stability and heat resistance of the film material, especially the need for laser drilling technology to realize signal intercommunication between different layers of multilayer flexible copper-clad plate, the existing LCP film material has a small process window during blind hole processing, and overheat overflow often occurs, increasing the difficulty of hole metallization. In addition, the processing of LCP film is usually by blowing film method, and the film thickness control is difficult, and the post-processing cost is high. Therefore, LCP film cannot be mass produced at present.

[0005] Polyphenyl ether (PPO) has excellent mechanical strength, stress relaxation resistance, creep resistance, heat resistance, water resistance, dimensional stability, flame resistance and self-extinguishing property. Its dielectric constant and dielectric loss are one of the smallest varieties in engineering plastics, and are almost not affected by temperature and humidity, and can be used in low, medium and high frequency electric field. The main disadvantage is poor melt flowability, difficult to process and shape, and not resistant to halogenated hydrocarbons and other organic solvents.

[0006] In the prior art CN1336944A, a polyphenyl ether-liquid crystal polymer blend composition with high arc track index is disclosed, which comprises (a) 50-95% by weight of polyphenyl ether based on the total weight of components (a) and (b); (b) 5-50% by weight of thermotropic liquid crystal polymer based on the total weight of components (a) and (b); and (c) an insulating filler in an amount sufficient to increase the relative tracking index (CTI) rating of the polymer blend to 220 volts or more, wherein the LCP exists in the form of a discontinuous phase or dispersed particles in the PPO. In this scheme, LCP and PPO are used as components, but only the two are blended, and a copolymer or polymer cannot be formed; and the actual technical problem to be solved by this prior art is to improve the arc track index, which is not related to the dielectric performance, and it is difficult to give an enlightenment for improving the dielectric performance.

[0007] Therefore, the present application proposes a scheme of using the two together to obtain an alloy film material with more excellent performance. SUMMARY

[0008] The present application aims to solve at least one of the above problems by providing an alloy film for a flexible circuit board, a preparation method and application thereof, so as to solve the defects that pure LCP film is difficult to prepare and process, and pure polyphenyl ether film is difficult to process and has poor solvent resistance, resulting in inability to realize practical application, in the prior art, LCP and polyphenyl ether are jointly formed into an alloy film through reaction, low dielectric constant and low dielectric loss are realized, and the alloy film also meets the processing characteristics of a flexible copper-clad plate material.

[0009] The object of the present application is achieved by the following technical solutions.

[0010] The present application discloses an alloy film for a flexible circuit board, which comprises the following components by weight:

[0011]

[0012] The polyphenyl ether and the liquid crystal polymer generate a polymer alloy under the action of a reaction catalyst.

[0013] Preferably, the polyphenyl ether is a non-functionalized polyphenyl ether, and the liquid crystal polymer is a thermotropic liquid crystal polymer.

[0014] Preferably, the thermotropic liquid crystal polymer has a melting point of 300-350 DEG C.

[0015] Preferably, the liquid crystal polymer comprises one or more of hydroquinone, 4,4'-dihydroxydiphenyl (4,4'-diphenol), isophthalic acid, terephthalic acid, p-hydroxybenzoic acid, p-hydroxybenzoic acid derivative, 4,4'-dihydroxydiphenyl (4,4'-diphenic acid), 4,4'-dihydroxydiphenyl (4,4'-diphenic acid) derivative, 2,6-naphthalene dicarboxylic acid and 6-hydroxy-2-naphthalene carboxylic acid.

[0016] Preferably, the reaction catalyst comprises one or more of boric acid, phosphoric acid, citric acid and sulfuric acid; and the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant CA, antioxidant 164, antioxidant DNP, antioxidant DLTP, antioxidant TNP, antioxidant TPP, antioxidant MB, antioxidant 264, MgO and ZnS.

[0017] Preferably, the reaction catalyst is a mixture of citric acid and phosphoric acid in equal weight ratio; and the antioxidant is antioxidant 1076.

[0018] Preferably, the alloy film further comprises 0-50% by weight of inorganic fillers, which include one or more of mica, kaolin, talc, glass beads, asbestos powder, quartz powder, montmorillonite, wollastonite and titanium white.

[0019] The second aspect of the present application discloses a method for preparing the alloy film for flexible circuit board as described in any of the above, comprising the following steps: mixing raw materials of the alloy film according to the formula, then adding into a double screw extruder for extrusion molding, followed by bidirectional stretching, corona treatment and edge cutting and winding to obtain the alloy film.

[0020] Preferably, the temperature of the barrel of the double screw extruder is: 50-265℃ for the first zone, 250-310℃ for the second zone, 250-340℃ for the third zone, 250-340℃ for the fourth zone, 250-340℃ for the fifth zone, 250-340℃ for the sixth zone, 250-340℃ for the seventh zone, 250-340℃ for the eighth zone, 250-340℃ for the ninth zone, and 250-340℃ for the tenth zone; the temperature of the die head is 250-340℃; the screw rotation speed is 200-500rpm; the feeding speed is 5-50kg / h; the torque is 50-99%; and the winding speed of the alloy film is 5-25m / min.

[0021] The third aspect of the present application discloses the application of the alloy film for flexible circuit board as described in any of the above in high frequency high speed circuit board.

[0022] The working principle of the present application is as follows:

[0023] The terminal hydroxyl groups on the PPO molecules and the carboxyl groups on the LCP molecular chains generate alloy copolymer and water molecules under the action of a catalyst, thereby playing a role of in-situ compatibilization.

[0024] The molecular chains of the PPO-LCP alloy film are oriented and orderly arranged in the direction parallel to the film plane through bidirectional stretching, and then the oriented macromolecular structure is fixed in the stretched state to obtain the "isotropic" film.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] The present application discloses a base film for flexible copper clad laminate (FCCL) composed of polyphenylene oxide (PPO) and liquid crystal polymer (LCP) and a preparation method thereof, which has the advantages of extremely small high frequency dielectric loss performance, excellent temperature resistance and good processing performance, etc. The flexible circuit board (FPC) prepared by using the base film of the present application can be widely used in electronic products such as mobile phones, digital cameras, digital video cameras, automobile satellite direction positioning devices, liquid crystal televisions, notebook computers, etc.

[0027] 1. The biggest advantage of the polyphenylene ether liquid crystal polymer resin film is that it can provide low dielectric constant, low dielectric loss, and meet the processing characteristics of flexible copper-clad plate materials. The circuit board made of the same has not only the demand of the existing high-frequency high-speed circuit board, but also the possibility of the development of more 5G products in the future due to its low density and high flame retardant performance.

[0028] 2. The reaction mechanism is that the terminal hydroxyl groups on the PPO molecules and the carboxyl groups on the LCP molecular chains generate alloy copolymer and water molecules under the action of the catalyst after the PPO is fully mixed under high temperature and high shear in the 1:1 mixture of citric acid and phosphoric acid, thereby playing the role of in-situ compatibilization. The water molecules are further devolatilized by the twin-screw extruder. Compared with the compatibilization effect of the existing solubilizer PPE-g-MAH, it is found that the compatibility of the present application is better, and the film forming performance is better.

[0029] 3. The use of a twin-screw extruder saves processing steps and manufacturing costs. At the same time, due to the technology that the ordinary single-screw extruder must pretreat the raw materials to produce a film, the possible quality process defects are avoided, and the film forming efficiency is improved.

[0030] 4. By using a biaxial stretching film device, the molecular chains of the PPO-LCP alloy high polymer are oriented and orderly arranged in the direction parallel to the film plane under the action of external force through longitudinal stretching and transverse stretching in sequence along the longitudinal direction and the transverse direction, and the oriented macromolecular structure is fixed in the stretched state. Finally, after cooling and subsequent treatment, the ideal "isotropic" film can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the preparation process of the alloy film. DETAILED DESCRIPTION

[0032] The present application will be described in detail below in conjunction with the drawings and specific examples.

[0033] In the following description, if not specifically stated, the reagents used are conventional commercially available products, and the methods used are well-known means in the art.

[0034] The present application discloses a base film for flexible copper-clad plate composed of polyphenylene ether (PPO) and liquid crystal polymer (LCP) and a preparation method thereof. The preferred composition film has low dielectric constant and low loss tangent in a specific process. The lower the loss tangent, the better the high-frequency signal can pass through without loss, thereby meeting the technical requirements of 5G millimeter wave signal transmission.

[0035] Supplementary note:

[0036] Loss Tangent and Dissipation Factor (tan δ / Df)

[0037] The dissipation factor can be used to measure the loss of the transmission line. The signal is transmitted from the transmitting end to the receiving end on the transmission line, and the electromagnetic wave is absorbed in the dielectric layer, which is called dielectric loss. With the rise of signal rate, the dielectric loss will also rise in proportion.

[0038] The influence of the dielectric loss (α d ) of the dielectric layer is shown in the formula:

[0039] α d =k×f×(ε r ) 1 / 2 ×tan δ

[0040] In the formula: k-constant; f-signal transmission frequency; tan δ-dielectric loss tangent

[0041] The influence of the dielectric loss (α d ) in FCCL mainly appears in the attenuation and heat consumption of the signal transmission process, and will rapidly increase with the high frequency and high speed digital signal transmission. Therefore, for high frequency and high speed digital signal transmission, the smaller the dielectric loss (α d ), the better, so the dielectric loss (α d ), dielectric constant (ε r ) of the dielectric layer of FCCL, especially the dielectric loss tangent tan δ, the smaller the better.

[0042] In addition, polyphenyl ether belongs to a non-fixed type of high molecular structure, and its glass transition temperature (T g ) is 215℃, the melting temperature (T m ) is 250℃, the intermolecular arrangement is disordered, and the isotropy is isotropic. LCP is a crystalline polymer structure, and its melting temperature is between 300-425℃, the intermolecular arrangement is neat, and the anisotropy is anisotropic. The present application utilizes the temperature difference between the glass transition temperature and the melting temperature of polyphenyl ether, and provides a larger processing window for LCP material during laser drilling of multilayer flexible copper-clad plate, and reduces the difficulty of material metallization in the hole. At the same time, by utilizing the isotropic characteristics of polyphenyl ether molecules, the processing difficulty of LCP film is reduced, and the uniformity of film thickness is improved.

[0043] The present application aims at the deficiencies of the prior art, and the main purpose is to provide an alloy composition of polyphenyl ether and liquid crystal polymer, and to prepare a base film for flexible copper-clad plate by double screw reaction extrusion and bidirectional film stretching equipment.

[0044] The composition comprises the following components:

[0045]

[0046] In this scheme, the polyphenylene ether (PPO) is a non-functionalized PPO, which means that the non-functionalized PPO does not have the presence of any additional functional groups. Preferably, a low viscosity PPO with a molecular weight between 21,000 and 25,000 is used, which is easier to mix.

[0047] The liquid crystal polymer is a thermotropic liquid crystal polymer, including thermotropic liquid crystal polyester and liquid crystal polyester-amide, polyester-imide, polyester-amide-imide or a blend thereof. The preferred polymer is a liquid crystal polyester, and the more preferred polyester is an aromatic polyester. As the wholly aromatic polyester component of the LCP composition in the present application, it can be: hydroquinone, 4,4'-dihydroxydiphenyl (4,4'-diphenol), isophthalic acid, terephthalic acid, p-hydroxybenzoic acid or its derivatives, 4,4'-dihydroxydiphenyl (4,4'-diphenic acid) or its derivatives, 2,6-naphthalene dicarboxylic acid, 6-hydroxy-2-naphthalene carboxylic acid, or any combination of the above components. It is further preferred to use an LCP with a melting point of about 300-350°C.

[0048] The inorganic filler is any one or several of mica, kaolin, talc powder, glass beads, asbestos powder, quartz powder, montmorillonite, wollastonite, titanium white powder, and is preferably glass beads.

[0049] The reaction catalyst is one or a mixture of boric acid, phosphoric acid, citric acid and sulfuric acid. Preferably, it is a mixture of citric acid and phosphoric acid in a mass ratio of 1:1, and its relative density is 1.6.

[0050] The antioxidant is any one or several of antioxidant 1010, antioxidant 1076, antioxidant CA, antioxidant 164, antioxidant DNP, antioxidant DLTP, antioxidant TNP, antioxidant TPP, antioxidant MB, antioxidant 264, MgO, ZnS, and is preferably antioxidant 1076.

[0051] The preparation method of the composition is to use a double screw extruder film production line, and the liquid crystal polymer and the polyphenylene ether composition are added into the extruder according to the above formula, and after bidirectional stretching, corona treatment, edge cutting and winding, a film is formed. The main equipment includes a high-speed mixer, a loss-in-weight feeder, a high-torque double screw extrusion line, a bidirectional stretching film device, a corona treatment device, an edge cutting and winding device. The specific process route is as follows Figure 1 .

[0052] Wherein, the process parameters of the double screw extrusion film production line are as follows: the barrel temperature of the extruder is 50-265℃ in the first zone, 250-310℃ in the second zone, 250-340℃ in the third zone, 250-340℃ in the fourth zone, 250-340℃ in the fifth zone, 250-340℃ in the sixth zone, 250-340℃ in the seventh zone, 250-340℃ in the eighth zone, 250-340℃ in the ninth zone, 250-340℃ in the tenth zone, and the die is 250-340℃; the screw rotation speed is 200-500 RPM, the feeding speed is 5-50 kg / h, and the torque is 50-99%. The film winding speed is 5-25 m / min.

[0053] In the following examples, the polyphenyl ether is Nantong Xingchen LXR040, the liquid crystal polymer is Ningbo Jiaxin New Material Co., Ltd. The base resin, citric acid, and phosphoric acid are purchased from Jingdong Guangxin, the antioxidant is AO1076 from BASF, the inorganic filler (except glass beads) is purchased from Komo Chemical, the maleic anhydride grafted polyphenyl ether (PPE-g-MAH) is FB820 from Jiaiyong, and the glass beads are purchased from Suzhou Jin Yi.

[0054] Example 1

[0055] After the composition A is uniformly mixed in a high-speed mixer at the following proportions, it is fed into a double screw extruder and a biaxial stretching film production line. The specific combination ratio is as follows:

[0056] Liquid crystal polymer 10 parts, polyphenyl ether 89.5 parts, reaction catalyst 0.2 parts (the reaction catalyst is a mixture of citric acid and phosphoric acid with a mass ratio of 1:1), antioxidant 0.3 parts.

[0057] After being uniformly mixed, it is extruded and cast into a film, and the extruder temperature is as follows: the first zone temperature is 265℃, the second zone temperature is 310℃, the third zone temperature is 320℃, the fourth zone temperature is 320℃, the fifth zone temperature is 320℃, the sixth zone temperature is 320℃, the seventh zone temperature is 320℃, the eighth zone temperature is 320℃, the ninth zone temperature is 320℃, the tenth zone temperature is 320℃, and the die is 330℃. Subsequently, after biaxial stretching, corona treatment, and edge cutting, a film is obtained. The performance results are shown in Table 1.

[0058] Example 2

[0059] After the composition B is uniformly mixed in a high-speed mixer at the following proportions, it is fed into a double screw extruder and a biaxial stretching film production line. The specific combination ratio is as follows:

[0060] Liquid crystal polymer 89.5 parts, polyphenyl ether 10 parts, reaction catalyst 0.2 parts (the reaction catalyst is a mixture of citric acid and phosphoric acid with a mass ratio of 1:1), antioxidant 0.3 parts.

[0061] The mixture was uniformly mixed, extrusion cast into a film, and the temperature of the extruder was: Zone 1 temperature 265°C, Zone 2 temperature 310°C, Zone 3 temperature 320°C, Zone 4 temperature 320°C, Zone 5 temperature 320°C, Zone 6 temperature 320°C, Zone 7 temperature 320°C, Zone 8 temperature 320°C, Zone 9 temperature 320°C, Zone 10 temperature 320°C, and the die temperature was 330°C. Subsequently, the film was formed by biaxial stretching, corona treatment, edge cutting and winding. The performance results are shown in Table 1.

[0062] Example 3

[0063] The composition C was uniformly mixed by a high-speed mixer in the following proportions and then fed into a twin-screw extruder and a biaxial stretching film production line by a feeder. The specific combination ratio is as follows:

[0064] Liquid crystal polymer 59.6 parts, polyphenyl ether 20 parts, glass beads 10 parts, titanium white 10 parts, reaction catalyst 0.2 parts (the reaction catalyst is a mixture of citric acid and phosphoric acid with a mass ratio of 1:1), antioxidant 0.2 parts.

[0065] The mixture was uniformly mixed, extrusion cast into a film, and the temperature of the extruder was: Zone 1 temperature 265°C, Zone 2 temperature 310°C, Zone 3 temperature 320°C, Zone 4 temperature 320°C, Zone 5 temperature 320°C, Zone 6 temperature 320°C, Zone 7 temperature 320°C, Zone 8 temperature 320°C, Zone 9 temperature 320°C, Zone 10 temperature 320°C, and the die temperature was 330°C. Subsequently, the film was formed by biaxial stretching, corona treatment, edge cutting and winding. The performance results are shown in Table 1.

[0066] Example 4

[0067] The composition D was uniformly mixed by a high-speed mixer in the following proportions and then fed into a twin-screw extruder and a biaxial stretching film production line by a feeder. The specific combination ratio is as follows:

[0068] Liquid crystal polymer 49.6 parts, polyphenyl ether 20 parts, glass beads 15 parts, titanium white 15 parts, reaction catalyst 0.2 parts (the reaction catalyst is a mixture of citric acid and phosphoric acid with a mass ratio of 1:1), antioxidant 0.2 parts.

[0069] The mixture was uniformly mixed, extrusion cast into a film, and the temperature of the extruder was: Zone 1 temperature 265°C, Zone 2 temperature 310°C, Zone 3 temperature 320°C, Zone 4 temperature 320°C, Zone 5 temperature 320°C, Zone 6 temperature 320°C, Zone 7 temperature 320°C, Zone 8 temperature 320°C, Zone 9 temperature 320°C, Zone 10 temperature 320°C, and the die temperature was 330°C. Subsequently, the film was formed by biaxial stretching, corona treatment, edge cutting and winding. The performance results are shown in Table 1.

[0070] Example 5

[0071] Composition E was mixed in a high speed mixer and fed into a twin screw extruder and a biaxial stretching film production line. The specific combination ratio is as follows:

[0072] Liquid crystal polymer 39.5 parts, polyphenyl ether 30 parts, glass beads 15 parts, titanium white 15 parts, reaction catalyst 0.2 parts (the reaction catalyst is a mixture of citric acid and phosphoric acid, the mass ratio is 1:1), antioxidant 0.3 parts.

[0073] It was mixed uniformly, extruded and cast into a film, the extruder temperature was: zone 1 temperature 265°C, zone 2 temperature 310°C, zone 3 temperature 320°C, zone 4 temperature 320°C, zone 5 temperature 320°C, zone 6 temperature 320°C, zone 7 temperature 320°C, zone 8 temperature 320°C, zone 9 temperature 320°C, zone 10 temperature 320°C, die head 330°C. Subsequently, after biaxial stretching, corona treatment, edge cutting and winding, a film was formed. The performance results are shown in Table 1.

[0074] Comparative Example 1

[0075] Composition F was mixed in a high speed mixer and fed into a twin screw extruder and a biaxial stretching film production line. The specific combination ratio is as follows:

[0076] This comparative example is a liquid crystal polymer that is not modified by blending.

[0077] It was extruded and cast into a film, the extruder temperature was: zone 1 temperature 265°C, zone 2 temperature 310°C, zone 3 temperature 320°C, zone 4 temperature 320°C, zone 5 temperature 320°C, zone 6 temperature 320°C, zone 7 temperature 320°C, zone 8 temperature 320°C, zone 9 temperature 320°C, zone 10 temperature 320°C, die head 330°C. Subsequently, after biaxial stretching, corona treatment, edge cutting and winding, a film was formed. The performance results are shown in Table 2.

[0078] Comparative Example 2

[0079] Composition G was mixed in a high speed mixer and fed into a twin screw extruder and a biaxial stretching film production line. The specific combination ratio is as follows:

[0080] This ratio is a polyphenyl ether molecule that is not modified by blending.

[0081] It was extruded and cast into a film, the extruder temperature was: zone 1 temperature 265°C, zone 2 temperature 310°C, zone 3 temperature 320°C, zone 4 temperature 320°C, zone 5 temperature 320°C, zone 6 temperature 320°C, zone 7 temperature 320°C, zone 8 temperature 320°C, zone 9 temperature 320°C, zone 10 temperature 320°C, die head 330°C. Subsequently, after biaxial stretching, corona treatment, edge cutting and winding, a film was formed. The performance results are shown in Table 2.

[0082] Comparative Example 3

[0083] The composition I was mixed homogeneously by high speed mixer and then fed into the twin-screw extruder and biaxial stretching film production line. The specific composition ratio was as follows:

[0084] Liquid crystal polymer 39.5 parts, maleic anhydride grafted polyphenyl ether (PPE-g-MAH) 30 parts, glass beads 15 parts, titanium dioxide 15 parts, reaction catalyst 0.2 parts (the reaction catalyst is a mixture of citric acid and phosphoric acid, the mass ratio is 1:1), antioxidant 0.3 parts.

[0085] It was mixed homogeneously, extruded and cast into a film, the extruder temperature was: zone 1 temperature 265℃, zone 2 temperature 310℃, zone 3 temperature 320℃, zone 4 temperature 320℃, zone 5 temperature 320℃, zone 6 temperature 320℃, zone 7 temperature 320℃, zone 8 temperature 320℃, zone 9 temperature 320℃, zone 10 temperature 320℃, die 330℃. Subsequently, after biaxial stretching, corona treatment, edge cutting and winding, a film was formed. The performance results are shown in Table 2.

[0086] Table 1 Summary of experimental data of Examples 1-5

[0087]

[0088]

[0089]

[0090] Table 2 Summary of experimental data of Comparative Examples 1-3

[0091]

[0092]

[0093] Conclusion:

[0094] 1. From the film forming property, Comparative Example 1 and Comparative Example 2 cannot form a film.

[0095] 2. From the film thickness tolerance requirement, Example 1, Example 2 and Comparative Example 3 cannot meet the requirements of IPC4101. (Generally, IPC requires that the thickness tolerance of the base film be less than 5%)

[0096] 3. All of Example 3, Example 4 and Example 5 can meet the requirements of film forming and film thickness tolerance, and can pass the test requirements of multi-layer soft board laser drilling. The addition of inorganic fillers enhances the thermal stability of the material. Among them, the film thickness tolerance of Example 5 can be controlled within 2%, the dielectric constant is 3.3, the dielectric loss tangent is 0.003, which is the most preferred composition. The film thickness tolerance of Example 4 can be controlled within 3%, which is a relatively preferred composition. Example 3 has a relatively large film thickness tolerance due to the high content of LCP, which is a relatively poor composition.

[0097] Comparing Example 5 of the present scheme and Comparative Example 3 with similar formula (using commercially available solubilizer PPE-g-MAH instead of LCP), it can be seen that the film thickness tolerance of the present scheme is greatly reduced and can meet the performance requirements, and the dielectric constant and dielectric loss tangent of the present scheme are smaller, and thus it has more desirable performance at high frequency, which can meet the performance requirements of 5G millimeter wave signal transmission.

[0098] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art according to the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. An application of an alloy thin film for flexible circuit boards, characterized in that, The alloy thin film is used in high-frequency and high-speed circuit boards; The alloy film comprises the following components in parts by weight: 30 parts of polyphenylene ether; 39.5 parts of liquid crystal polymer; 0.2 parts of reaction catalyst; Antioxidant 0.3 parts; 30 parts of inorganic filler; The polyphenylene ether and the liquid crystal polymer react to form a polymer alloy under the action of a reaction catalyst. The polyphenylene ether is Nantong Xingchen LXR040, and the liquid crystal polymer is copolymen from Ningbo Juji New Materials Co., Ltd. ® The matrix resin is a thermotropic liquid crystal polymer with a melting point of 300-350℃; the reaction catalyst is a mixture of citric acid and phosphoric acid in equal weight ratio; the antioxidant is BASF's AO1076; the inorganic filler is a mixture of glass microspheres and titanium dioxide in equal weight ratio. The preparation method of the alloy film includes the following steps: the raw materials for the alloy film are premixed according to the formula and then extruded in a twin-screw extruder. After biaxial stretching, corona treatment and edge trimming and winding, the alloy film is obtained. The barrel temperature of the twin-screw extruder is as follows: Zone 1 temperature 265℃, Zone 2 temperature 310℃, Zone 3 temperature 320℃, Zone 4 temperature 320℃, Zone 5 temperature 320℃, Zone 6 temperature 320℃, Zone 7 temperature 320℃, Zone 8 temperature 320℃, Zone 9 temperature 320℃, Zone 10 temperature 320℃, and the die head temperature 330℃. The alloy thin film has a thickness tolerance of 2%, a dielectric constant of 3.3 at 1 GHz, and a dielectric loss tangent of 0.003 at 1 GHz.

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