阅读说明：本技术 一种用于毫米波太赫兹频段的柔性介质薄膜及其制备方法 (Flexible dielectric film for millimeter wave terahertz frequency band and preparation method thereof ) 是由 蔡龙珠 洪伟 蒋之浩 陈晖� 于 2020-12-18 设计创作，主要内容包括：本发明公开了一种用于毫米波太赫兹频段的柔性介质薄膜及其制备方法,包括柔性介质薄膜加工过程和控制条件,以及毫米波与太赫兹频段介电特性。制备方法包括如下步骤：颗粒获取,烘干加料,密封干燥,加热融化,压延挤出,性能测试,表面金属化。采用上述工艺对树脂材料进行温控等操作,形成的新型柔性介质薄膜可以拥有优越的介电特性,测试结果显示所加工形成的柔性介质薄膜具有极低的介电常数,在极宽频带下有很好的介电稳定性,介质损耗正切值比常用的高频介质基板低一个数量级,同时具有较高的光透明度。通过在该介质薄膜表面实现金属化操作,利用蚀刻等方式实现高频电路,对包含5G和6G在内的未来通信具有极大的应用前景。(The invention discloses a flexible dielectric film for a millimeter wave terahertz frequency band and a preparation method thereof. The preparation method comprises the following steps: obtaining particles, drying and feeding, sealing and drying, heating and melting, calendering and extruding, testing performance and metalizing the surface. The novel flexible dielectric film formed by adopting the process to carry out temperature control and other operations on the resin material can have excellent dielectric properties, and test results show that the flexible dielectric film formed by processing has extremely low dielectric constant and good dielectric stability under an extremely wide frequency band, and the dielectric loss tangent value is one order of magnitude lower than that of a common high-frequency dielectric substrate and has higher light transparency. By realizing metallization operation on the surface of the dielectric film and realizing a high-frequency circuit by etching and the like, the method has great application prospect for the future communication including 5G and 6G.)

1. A flexible dielectric film for a millimeter wave terahertz frequency band and a preparation method thereof are characterized in that the preparation method comprises the following steps:

step 1, particle acquisition: the preparation method comprises the steps of carrying out copolymerization on two monomers of doped norbornene and ethylene under the action of a metathesis polymerization catalyst, washing and drying, and finally carrying out high-speed ball milling and low-speed ball milling on zirconium oxide balls to obtain cycloolefin copolymer particles with uniform sizes;

step 2, drying and feeding: drying the cycloolefin copolymer particles by a dryer, and pouring the particles into a hopper device;

and 3, sealing and drying: conveying the cyclic olefin copolymer particles to a drying chamber through a pump and a conveying belt for further sealing and drying, wherein the temperature of the drying chamber is kept at 100-140 ℃;

and 4, heating and melting: conveying the dried particles into a high-temperature cylinder through a transmission device, heating by using a mica heater, and keeping the temperature at 260-320 ℃ for 10-15 minutes according to the corresponding glass transition temperature to ensure that the particles are completely in a liquid flowing state;

and step 5, calendering and extruding: the driving motor is directly connected with the speed reducer, the output shaft of the speed reducer is connected with the screw, the screw is driven to rotate at the rotating speed of 60-100rpm, the current of the driving motor is kept at 80-90A, so that the cycloolefin copolymer in the flowing state is extruded by the casting die head, and then the cycloolefin copolymer is rolled by a two-roll calender to form the flexible medium film of the cycloolefin copolymer, and then the flexible medium film is naturally cooled, wherein the temperature of one cooling roll is 140 ℃ and the temperature of the other cooling roll is 100 ℃ and 120 ℃;

and 6, performance testing: carrying out flatness and uniformity tests on the obtained novel olefin copolymer flexible dielectric film under the condition of all media, and carrying out dielectric property tests in a millimeter wave terahertz frequency band;

step 7, surface metallization: and carrying out surface metallization on the surface of the cycloolefin copolymer medium film by methods such as magnetron sputtering, electron beam evaporation and the like.

2. The flexible dielectric film for the millimeter wave terahertz frequency band and the preparation method thereof as claimed in claim 1, wherein in the calendering extrusion, the temperature and speed of each part are adjusted according to the kind of resin to obtain a high-quality flexible film with a thickness of millimeter level.

3. The flexible dielectric film for the millimeter wave terahertz frequency band and the preparation method thereof as claimed in claim 1, wherein in the performance test, the dielectric properties of the flexible dielectric film in the millimeter wave and terahertz frequency bands can be obtained by a millimeter wave open resonator system and a terahertz time-domain spectrum analyzer respectively.

4. The flexible dielectric film for the millimeter wave terahertz frequency band and the preparation method thereof as claimed in claim 1, wherein in the surface metallization, when the surface bonding force between the metal and the cyclic olefin copolymer dielectric film is insufficient, a layer of metal such as titanium/chromium/platinum needs to be deposited as an adhesion transition layer first to enhance the bonding force between the metal and the dielectric film, and when the bonding force is sufficient, the metallization coating operation can be directly performed.

5. The flexible dielectric film for the millimeter wave terahertz frequency band and the preparation method thereof according to claim 1, wherein in the heating and melting, for the cyclic olefin copolymer particles with the glass transition temperature of about 178 degrees centigrade, in the heating and melting operation, a mica heater is used for heating, and the temperature is kept at 300 degrees centigrade for about 10 minutes until the particles are completely in a liquid flowing state.

6. The flexible dielectric film for the millimeter wave terahertz frequency band and the preparation method thereof as claimed in claim 1, wherein in the calendering extrusion, the screw is driven to rotate at a rotation speed of 80rpm, the current of the driving motor is kept at 90A, so that the cycloolefin copolymer in a flowing state is extruded through the casting die head, and then the film is calendered by a two-roll calender to form the novel flexible dielectric film of the olefin copolymer, and then the film is naturally cooled, so that the novel flexible dielectric film of the olefin copolymer with the thickness of 0.3mm is obtained.

7. According toThe flexible dielectric film for a millimeter wave terahertz frequency band and the preparation method thereof as claimed in claim 1, wherein the dielectric constant of the flexible dielectric film for a millimeter wave terahertz frequency band measured at 34GHz of millimeter wave is 2.36, and the dielectric loss tangent is 6.6 x 10^-4And the terahertz frequency band has low dielectric constant of 2.31 and low dispersion: the dielectric constant of 0.2-2.2THz in an extremely wide frequency band is kept stable; low dielectric loss tangent: 1X 10 in the very wide band 0.3-2.2THz^-4And 3X 10^-3Meanwhile, the transparent film has high visible light transparency.

Technical Field

The invention relates to a film material with excellent dielectric property suitable for being used for a high-frequency circuit, in particular to a novel flexible dielectric film with extremely low dielectric constant and dielectric loss in a millimeter wave terahertz frequency band and a preparation process thereof.

Background

In recent years, electronic products have been developed in a direction of miniaturization, multi-functionalization, high performance, and flexibility, and high capacity and high frequency required for high-speed processing of transmission information have been developed. With the rapid development of electronic information, the high-frequency copper-clad plate with the conventional performance can not meet the application requirements. The commonly used printing medium substrate materials at present comprise epoxy resin and phenol resin, but in a high-frequency region, particularly a millimeter wave terahertz frequency band, the dielectric properties of the epoxy resin and the phenol resin are poor, the transmission loss is large, and the performance of a high-frequency circuit is seriously influenced. Based on such a current situation, more and more research interest has been focused on developing a dielectric substrate having excellent dielectric characteristics that can be used for a high-frequency circuit. In order to achieve flexibility and conformability, some high frequency devices now attempt to use flexible high temperature mylar and other flexible braids, but the performance is often not ideal. Therefore, the requirement of the communication field for matching the dielectric constant, the dielectric loss and the processability of the novel flexible dielectric film is very urgent, and how to obtain the novel flexible dielectric film with low dielectric constant, low dispersion and low dielectric loss becomes a research hotspot.

Disclosure of Invention

The technical problem is as follows: in view of the needs of technical development, the invention provides a flexible dielectric film for a millimeter wave terahertz frequency band and a preparation method thereof, the flexible dielectric film is a novel flexible dielectric film with extremely low dielectric constant and dielectric loss in the millimeter wave terahertz frequency band, and a unique novel preparation method is adopted according to the chemical and physical properties of the flexible dielectric film to realize the preparation of the novel flexible dielectric film for the millimeter wave terahertz frequency band with excellent dielectric properties (such as low dielectric constant, low dispersion and low dielectric loss).

The technical scheme is as follows: in order to achieve the purpose, the flexible dielectric film for the millimeter wave terahertz frequency band and the preparation method thereof adopt the following technical scheme:

step 1, particle acquisition: the preparation method comprises the steps of carrying out copolymerization on two monomers of doped norbornene and ethylene under the action of a metathesis polymerization catalyst, washing and drying, and finally carrying out high-speed ball milling and low-speed ball milling on zirconium oxide balls to obtain cycloolefin copolymer particles with uniform sizes;

step 2, drying and feeding: drying the cycloolefin copolymer particles by a dryer, and pouring the particles into a hopper device;

and 3, sealing and drying: conveying the cyclic olefin copolymer particles to a drying chamber through a pump and a conveying belt for further sealing and drying, wherein the temperature of the drying chamber is kept at 100-140 ℃;

and 4, heating and melting: conveying the dried particles into a high-temperature cylinder through a transmission device, heating by using a mica heater, and keeping the temperature at 260-320 ℃ for 10-15 minutes according to the corresponding glass transition temperature to ensure that the particles are completely in a liquid flowing state;

and step 5, calendering and extruding: the driving motor is directly connected with the speed reducer, the output shaft of the speed reducer is connected with the screw, the screw is driven to rotate at the rotating speed of 60-100rpm, the current of the driving motor is kept at 80-90A, so that the cycloolefin copolymer in the flowing state is extruded by the casting die head, and then the cycloolefin copolymer is rolled by a two-roll calender to form the flexible medium film of the cycloolefin copolymer, and then the flexible medium film is naturally cooled, wherein the temperature of one cooling roll is 140 ℃ and the temperature of the other cooling roll is 100 ℃ and 120 ℃;

and 6, performance testing: carrying out flatness and uniformity tests on the obtained novel olefin copolymer flexible dielectric film under the condition of all media, and carrying out dielectric property tests in a millimeter wave terahertz frequency band;

step 7, surface metallization: and carrying out surface metallization on the surface of the cycloolefin copolymer medium film by methods such as magnetron sputtering, electron beam evaporation and the like.

Wherein the content of the first and second substances,

in the calendering extrusion, the temperature and speed of each part are adjusted according to the type of resin to obtain a high-quality flexible film with a thickness of millimeter level.

In the performance test, the dielectric properties of the flexible dielectric film in the millimeter wave and terahertz frequency bands can be respectively obtained by a millimeter wave open type resonant cavity system and a terahertz time-domain spectrum analyzer.

In the surface metallization, when the surface bonding force between the metal and the cycloolefin copolymer medium film is insufficient, a layer of metal such as titanium/chromium/platinum and the like is required to be deposited firstly as a bonding transition layer to enhance the bonding force between the metal and the medium film, and when the bonding force is enough, the metallization coating operation can be directly carried out.

In the heating and melting process, a mica heater is adopted to heat the cyclic olefin copolymer particles with the glass transition temperature of about 178 ℃ in the heating and melting operation, so that the temperature is kept at 300 ℃ for about 10 minutes until the particles are completely in a liquid flowing state.

In the calendering extrusion, the screw is driven to rotate at the rotating speed of 80rpm, the current of the driving motor is kept at 90A, so that the cycloolefin copolymer in a flowing state is extruded through the calendering die head, and then the cycloolefin copolymer is calendered by a two-roll calender to form the novel flexible medium film of the cycloolefin copolymer and then is naturally cooled to obtain the novel flexible medium film of the olefin copolymer with the thickness of 0.3 mm.

The flexible dielectric film for the millimeter wave terahertz frequency band has a dielectric constant measured at 34GHz of millimeter waveThe number was 2.36 and the dielectric loss tangent was 6.6X 10^-4And the terahertz frequency band has low dielectric constant of 2.31 and low dispersion: the dielectric constant of 0.2-2.2THz in an extremely wide frequency band is kept stable; low dielectric loss tangent: 1X 10 in the very wide band 0.3-2.2THz^-4And 3X 10^-3Meanwhile, the transparent film has high visible light transparency.

Has the advantages that: the invention discloses a novel flexible dielectric film with extremely low dielectric constant and dielectric loss in a millimeter wave terahertz frequency band and a preparation process thereof, and compared with the prior art, the novel flexible dielectric film has the following beneficial effects:

(1) the invention provides a novel flexible dielectric film with extremely low dielectric constant and dielectric loss in a millimeter wave terahertz frequency band and a preparation process thereof, wherein the novel flexible dielectric film has excellent dielectric properties such as low dielectric constant, low dispersion and low dielectric loss in the millimeter wave terahertz frequency band, and has great application potential in the millimeter wave terahertz frequency band;

(2) the invention provides a novel flexible dielectric film with extremely low dielectric constant and dielectric loss in a millimeter wave terahertz frequency band and a preparation process thereof.

(3) The invention provides a novel flexible dielectric film with extremely low dielectric constant and dielectric loss in a millimeter wave terahertz frequency band and a preparation process thereof, which are simple to operate, low in cost and convenient to integrate, and can meet the requirement of matching of the dielectric constant, the dielectric loss and the processability.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive exercise.

FIG. 1 is a flow chart of a process for preparing a novel flexible medium film of a cycloolefin copolymer according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating the dielectric constant test result of the novel flexible dielectric film made of cyclic olefin copolymer in the embodiment of the present invention in the terahertz frequency band.

FIG. 3 is a graph of the dielectric loss tangent test result of the novel flexible dielectric film of cycloolefin copolymer in the terahertz frequency band, which is realized in the embodiment of the present invention.

Detailed Description

The novel flexible dielectric film with extremely low dielectric constant and dielectric loss in the millimeter wave terahertz frequency band and the preparation method thereof have the advantages of simple operation process, easiness for large-scale batch production and wide application field, and the preparation method has generality and generally comprises the following steps: obtaining particles, drying and feeding, heating and melting, rolling and extruding, testing performance and metalizing the surface.

The particles are obtained by carrying out copolymerization reaction on two monomers of norbornene and ethylene which are doped with a certain proportion under the action of a metathesis polymerization catalyst, washing and drying, and finally carrying out high-speed ball milling and low-speed ball milling on zirconium oxide balls to obtain the cycloolefin copolymer particles with uniform size.

And (3) drying and feeding, namely drying the cycloolefin copolymer particles by a dryer, and pouring the particles into a feeding hopper device.

And (3) sealing and drying, namely conveying the cycloolefin copolymer particles to a drying chamber through a pump and a conveying belt for further sealing and drying, wherein the temperature of the drying chamber is kept at about 100-140 ℃.

And heating and melting, namely conveying the dried particles into a high-temperature cylinder through a transmission device, heating by adopting a mica heater, and keeping the temperature at 260-320 ℃ for 10-15 minutes according to the corresponding glass transition temperature so as to ensure that the particles are completely in a liquid flowing state.

The calendering extrusion is that a driving motor is directly connected with a speed reducer, the output shaft of the speed reducer is connected with a screw, the screw is driven to rotate at the rotating speed of 60-100 revolutions per minute (rpm), the current of the driving motor is kept at 80-90A, so that the cycloolefin copolymer slurry in the flowing state is extruded through a casting die head, and then is naturally cooled after being calendered by two rollers to form the flexible medium film of the cycloolefin copolymer, wherein the temperature of one cooling roller is about 120-140 ℃, and the temperature of one cooling roller is about 100-120 ℃. The temperature and speed of each part can be adjusted according to the resin type to obtain a high-quality flexible film with the thickness of millimeter level.

And the performance test is to carry out flatness and uniformity test on the obtained cycloolefin copolymer novel flexible medium film and to carry out dielectric property test in a millimeter wave terahertz frequency band. The dielectric properties of the dielectric film in the millimeter wave and terahertz frequency bands can be respectively obtained by a millimeter wave open type resonant cavity system and a terahertz time-domain spectrum analyzer.

The surface metallization is attached to the surface of the cycloolefin copolymer flexible medium film, and the surface metallization is carried out on the surface of the cycloolefin copolymer flexible medium film, and a single conductive metal film material, a conductive metal compound or a conductive alloy material of at least one metal material can be selected.

The metal conductive film can be obtained by any one of magnetron sputtering, electron beam evaporation and the like. When the surface bonding force between the metal with a certain thickness and the cycloolefin copolymer medium film is insufficient, a layer of metal such as titanium/chromium/platinum and the like can be deposited firstly to be used as a bonding transition layer so as to enhance the bonding force between the metal and the flexible medium film.

The temperature/time/current/rotation speed in the scheme can be adjusted according to the type and the characteristics of the cycloolefin copolymer, and after a person skilled in the art reads the patent application, various modifications can be made on the invention without departing from the spirit and the scope of the invention, and a novel medium film meeting the general requirements can be obtained without creative efforts.

By adopting the flexible medium film processing technology and carrying out metallization operation on the surface of the medium film in a certain mode, the novel cycloolefin copolymer flexible medium film formed in the way can have high uniformity and high flatness while having excellent dielectric properties (low dielectric constant, low dispersion and low dielectric loss), and can meet the requirements of the existing electronic equipment.

The technical solution of the present invention will be further described with reference to the following embodiments. The technical solutions in the embodiments of the present invention are clearly and completely described by referring to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The first embodiment is as follows: referring to fig. 1, a flow chart of a process for preparing a novel flexible medium film of a cycloolefin copolymer according to an embodiment of the present invention is shown, wherein the preparation method comprises the following steps:

(S1) (particle acquisition) two kinds of monomers of norbornene and ethylene which are mixed are subjected to copolymerization reaction, washing and drying, high-speed ball milling and low-speed ball milling operations under the action of a metathesis polymerization catalyst to obtain the cycloolefin copolymer particles with uniform size, so that the density of the cycloolefin copolymer particles is 1000Kg/m³The water absorption rate at room temperature was about 0.01%, and the glass transition temperature was about 178 ℃.

S2 (drying and charging) the cycloolefin copolymer pellets were dried by a dryer and poured into a hopper device.

S3, (seal drying) conveying the cyclic olefin copolymer particles to a drying chamber through a pump and a conveyer belt for further seal drying, wherein the temperature of the drying chamber is kept at about 120 ℃.

(heated melt) the dried granules were transferred to a high temperature barrel via a transmission, heated with a mica heater and held at 300 ℃ for about 10 minutes according to their corresponding glass transition temperature, leaving the granules completely in a liquid flowing state.

(S5) (calendering and extruding) is directly connected with a speed reducer through a driving motor, the output shaft of the speed reducer is connected with a screw, the screw is driven to rotate at the rotating speed of 80rpm, the current of the driving motor is kept at 90A, so that the cycloolefin copolymer in a flowing state is extruded through a casting die head, and then the cycloolefin copolymer is calendered through a two-roll calender to form the novel flexible medium film of the cycloolefin copolymer, and then the novel flexible medium film is naturally cooled. One cooling roll of the two roll calender is at about 140 degrees celsius and the other is at about 120 degrees celsius.

S6, (performance test) carrying out flatness and uniformity test on the obtained novel olefin copolymer flexible dielectric film, and testing the dielectric property of the substrate in a millimeter wave terahertz frequency band. The dielectric properties of the dielectric film in the millimeter wave and terahertz frequency bands can be respectively obtained by a millimeter wave open type resonant cavity system and a terahertz time-domain spectrum analyzer. If the application requirements are not met, the film is recycled, and the next step is continued from the step S2. Finally, the dielectric constant of 2.36 and the dielectric loss tangent of 6.6 x 10 in the millimeter wave band (34GHz) were successfully obtained^-4The dielectric constant and the dielectric loss tangent of the novel flexible dielectric film measured in the terahertz frequency band are shown in fig. 2 and fig. 3. In order to show its excellent characteristics, the test data of quartz and RT5880 are put in both figures, and the results show that the prepared novel dielectric film has low dielectric constant (about 2.31), low dispersion (the dielectric constant is kept stable in the ultra-wide band of 0.2-2.2 THz), and low dielectric loss tangent (1 × 10 in the ultra-wide band of 0.2-2.2 THz)^-4And 3X 10^-3In between).

S7. (surface metallization) after the performance of the novel flexible film obtained in the S6 meets the requirement, the surface of the medium film is plated with metal gold with the thickness of 100 nanometers through magnetron sputtering.

In the above embodiments, the present invention has been described only by way of example, and the above description of the embodiments is only used to help understanding the method of the present invention and its core idea; also, after reading this patent application, it will be apparent to those skilled in the art that various modifications can be made in the present invention without departing from the spirit and scope of the invention, and that various changes can be made in the embodiments and applications of the invention. In view of the above, the present disclosure should not be construed as limiting the invention.