Production method of LCP (Liquid Crystal Polymer) film

Abstract

The invention discloses a production method of an LCP (Liquid Crystal Polymer) film. The production method of the LCP film comprises the following steps: S1, sequentially melting LCP, extruding the LCP through a forming die, and carrying out curtain coating and cooling to obtain a first film; s2, the two first films are stretched in an environment containing treatment gas after being attached, then the two first films attached together are separated, and two second films are obtained; s3, the second film is sequentially subjected to traction, edge cutting and rolling, and the LCP film is obtained; the treatment gas has one or more properties of acidity, corrosivity and oxidizability to the first film. The production method of the LCP film has the advantages that the binding force of the LCP film and the copper foil is improved, and the performance effect of the LCP film is kept.

Description

Technical Field

[0001] The invention belongs to the technical field of polymers, and in particular relates to a method for producing an LCP film. Background Art

[0002] LCP copper clad laminate, also known as (LCP for short) copper clad laminate, is a two-layer glue-free flexible copper clad laminate (2L-FCCL) with liquid crystal polymer as the insulating layer material. It is a high-performance flexible copper clad laminate.

[0003] LCP material is a new type of polymer material, which generally exhibits liquid crystal properties in the molten state. LCP material has excellent high temperature resistance and high strength performance, excellent electrical properties, chemical corrosion resistance, good dimensional stability and excellent flame retardancy, etc. It is widely used in the fields of electronics, aerospace, medical materials, industrial products and packaging films.

[0004] LCP film has the characteristics of low dielectric constant and low dielectric loss, which makes it perform well in high-frequency signal transmission. In 5G communications, the transmission efficiency and quality of high-frequency signals are crucial, and LCP film just meets this demand. At the same time, LCP film is a thermoplastic resin that can be directly hot-pressed with copper foil under heat preservation, without the need to pre-coat the film surface. The composite process is simple, environmentally friendly and efficient.

[0005] The commonly used LCP film preparation process is the extrusion stretching method, which is to extrude the molten LCP through a T-shaped molding die, cast it, cool it, stretch it, and then haul it, trim it, and then roll it up to finally get the LCP film product. Among them, the stretching of LCP needs to be carried out at a relatively high temperature, usually between 180℃ and 340℃. Then haul it, trim it, and then roll it up to finally get the LCP film product.

[0006] However, the bonding strength between LCP film and copper foil is poor. Common reasons are as follows: ①LCP film has a highly ordered molecular structure, which makes it have a regular structure in the molten state, with molecules arranged side by side. This highly ordered structure may cause the surface of LCP film to be relatively smooth, lacking the microscopic roughness or chemically active sites required for bonding with copper foil, thus affecting the bonding strength between the two.

[0007] ②LCP film may not react chemically with copper foil easily due to the stability of its molecular structure and chemical inertness, thus limiting the chemical bonding between them. This chemical inertness means that without proper surface treatment, the bonding between LCP film and copper foil mainly relies on physical forces, such as van der Waals forces, which are usually weaker than chemical bonding.

[0008] ③The anisotropy of LCP film performance may lead to inconsistent bonding performance in different directions. The high degree of molecular orientation may cause the LCP film to have higher strength and stiffness in some directions, but relatively weak in other directions, which affects the uniform bonding with copper foil.

[0009] At present, there are methods on the market to improve the bonding strength between LCP film and copper foil by modifying LCP, irradiating with ultraviolet light, etc. Modifying LCP can change the regularity of LCP molecules and the intermolecular forces at the interface between LCP film and copper foil, while irradiating with ultraviolet light can change the regularity of LCP molecules and the roughness of the LCP film surface.

[0010] However, these methods will reduce the regularity of LCP molecules, thereby affecting the mechanical properties, heat resistance, dimensional stability, chemical stability and dielectric properties (including dielectric constant and dielectric loss) of LCP films. Summary of the invention

[0011] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for producing an LCP film.

[0012] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: A method for producing an LCP film comprises the following steps: S1, melting LCP, extruding it through a forming die, and cooling it to obtain a first film; S2, laminating the two first films and stretching them in an environment containing a processing gas, and then separating the two laminated first films to obtain two second films; S3, pulling, trimming, and rolling up the second film in sequence to obtain an LCP film; The processing gas has one or more properties of acidity, corrosiveness, and oxidation to the first film.

[0013] In the present invention, micro-tears may occur on the surface of the LCP film during the stretching process due to the following reasons: ① During the stretching process, the LCP molecular chains will be oriented along the stretching direction. In the actual production process, the stretching process cannot be completely uniform. When the local area is overstretched, tiny tears will occur between the molecular chains; ②LCP film is prone to anisotropy during the preparation process, that is, it has different physical properties in different directions. During the traction and stretching process, the uneven stress distribution caused by anisotropy will form weak points in certain directions of the LCP film, thereby causing micro-tears; ③Defects in the LCP film during the preparation process, such as micropores, impurities or uneven crystal areas, become areas of stress concentration during the stretching process, resulting in micro-tears.

[0014] When the LCP film surface is slightly torn, the following effects will occur: ① The tear is in an exposed state, with a higher surface energy, making it easier to react with the processing gas; ② The microstructure at the tear may be different from the original surface, and there may be more defects and irregularities. These structural changes can provide more active sites, thereby increasing the probability of reaction with the process gas.

[0015] In the present invention, the melting point of LCP is mostly between 180° C. and 340° C. At this temperature, the reaction activity of the processing gas and LCP is increased, and the processing gas can corrode or oxidize some molecules on the surface of the LCP film.

[0016] Preferably, the processing gas is selected from one or more of HCl (hydrogen chloride), O2 (oxygen), O3 (ozone), and Cl2 (chlorine).

[0017] In the present invention, O3 is specifically selected as the processing gas.

[0018] Preferably, the concentration of the processing gas is 0.01 mol / m 3 ~0.1mol / m 3 .

[0019] Preferably, in step S2, the two first films bonded together are separated, cleaned with an alkaline alcohol solution, rinsed with deionized water, and dried to obtain two second films.

[0020] The alcohol solution of alkali in the present invention can elute some groups on the surface of the LCP film, which is beneficial to improving the roughness of the surface of the LCP film; at the same time, some groups are converted into oxygen-containing groups, which is beneficial to the uniformity of the surface properties of the LCP film; alcohol has high polarity and good dissolving ability, and can dissolve the groups, impurities, etc. that fall off the LCP film, which is beneficial to improving the roughness of the surface of the LCP film.

[0021] The alkali alcohol solution has low corrosiveness to the LCP film and will not cause new corrosion to the LCP film, which is beneficial to avoid excessive corrosion of the LCP film; at the same time, the alkali alcohol solution can elute the groups detached from the surface of the LCP film, which is beneficial to increase the roughness of the surface of the LCP film.

[0022] Preferably, the alcoholic base solution comprises a strong base and an alcohol; In the present invention, the strong base is selected from one or more of NaOH (sodium hydroxide), KOH (potassium hydroxide), and Ba(OH)2 (barium hydroxide).

[0023] In the present invention, the strong base is specifically selected from NaOH.

[0024] In the present invention, the alcohol is selected from one or more of ethanol, isopropanol, n-butanol, cyclohexanol and ethylene glycol.

[0025] In the present invention, the alcohol is specifically selected from ethanol.

[0026] Preferably, the concentration of the alkali alcohol solution is 5 to 10 g / L.

[0027] In the present invention, the concentration of the NaOH ethanol solution is selected to be 5 g / L.

[0028] Preferably, in step S2, after the two first films are bonded together, ultraviolet rays are irradiated onto the two first films during the stretching process.

[0029] Preferably, the irradiation intensity of the ultraviolet light is 500 to 2000 μW / cm 2 .

[0030] In the present invention, low-intensity ultraviolet rays are not sufficient to stimulate the breaking of chemical bonds in the LCP molecular chain or initiate photochemical reactions, so low-intensity ultraviolet rays will not destroy the molecular structure inside the LCP film; at the same time, ultraviolet rays can increase the activity of the LCP film surface, thereby promoting the oxidation reaction on the LCP film surface.

[0031] The main raw materials of the present invention are introduced as follows: HCl: HCl can act as a mild oxidant with a relatively slow reaction rate, which helps to control the oxidation process on the surface of the LCP film and avoid over-oxidation, thereby protecting other properties of the LCP film from damage.

[0032] O2: Oxygen is an oxidant widely present in the natural environment. Using O2 as an oxidant will not introduce additional harmful chemicals and is environmentally friendly.

[0033] O3: Ozone is a strong oxidant that can quickly oxidize the surface of LCP film, increase surface energy, and thus improve bonding or printing performance. Ozone reacts very quickly with organic matter, and can achieve rapid oxidation of the surface of LCP film in a short time.

[0034] Cl2: Chlorine is a strong oxidant that can effectively oxidize the surface of LCP film, increase surface polarity, and improve bonding strength with the substrate.

[0035] Compared with the prior art, the advantages of the present invention include: (1) The present invention provides a method for producing an LCP film. After the surface of the LCP film reacts with the treatment gas, new groups are formed on the surface of the LCP film. After the treatment gas corrodes the surface of the LCP film, the roughness of the surface of the LCP film can be increased. The increase of new groups and roughness on the surface of the LCP film is beneficial to improving the bonding strength between the LCP film and the copper foil. (2) The present invention provides a method for producing an LCP film. After a tiny tear occurs on the surface of the LCP film, the torn portion is easily reacted with the processing gas, thereby making use of the inevitable defects in the production process and converting the inevitable defects in the production process into factors that are beneficial to the bonding of the LCP film and the copper foil; (3) The present invention provides a method for producing an LCP film. After a tiny tear occurs on the surface of the LCP film, the tear reacts with the processing gas, and the defects on the surface of the LCP film during the production process are magnified, which can increase the roughness of the surface of the LCP film, thereby improving the bonding strength between the LCP film and the copper foil. (4) The present invention provides a method for producing an LCP film, which transforms the inevitable defects in the production process of the LCP film into factors that are beneficial to the bonding of the LCP film and the copper foil, thereby reducing the damage to the flat area of ​​the LCP film and facilitating the maintenance of the performance of the LCP film; (5) The present invention provides a method for producing an LCP film, wherein two first films are laminated and then stretched in an environment containing a treatment gas, wherein the treatment gas reacts with only one side of the LCP film. The treatment gas can change the properties of only one side of the LCP film without affecting the regularity of the LCP film molecules, which is beneficial to maintaining the performance of the LCP film. (6) The present invention provides a method for producing an LCP film, wherein two first films are laminated and then stretched in an environment containing a processing gas. During the stretching process, the surface area of ​​the LCP film gradually increases, which is beneficial to maintaining the uniformity of the reaction rate between the LCP film and the processing gas, thereby facilitating reducing fluctuations in the concentration of the processing gas. (7) The present invention provides a method for producing an LCP film, wherein two first films are bonded together and then stretched in an environment containing a treatment gas. During the stretching process, the LCP film is simultaneously treated with the treatment gas. The temperature required for stretching can also increase the reactivity of the treatment gas, which is beneficial to improving production efficiency and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 This is a schematic diagram of the stretching process of a method for producing an LCP film in Example 4 of the present invention.

[0038] Reference numerals: 1. Stretching box; 2. UV lamp. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to understand the characteristics and effects of the present application, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the common meanings understood by those skilled in the art for the present application. In case of conflict, the definitions in this specification shall prevail.

[0040] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present application in any way, that is, the content of the present application can be implemented without being limited by any specific theory or mechanism.

[0041] As used herein, "this application" means "the present invention" or "the present disclosure".

[0042] The use of "one", "an", "a kind" or similar expressions to describe the components and technical features described in this application is merely for the convenience of expression and to provide a general meaning to the scope of this application. Therefore, such description should be understood to include one or at least one, and the singular also includes the plural, unless it is obvious that it refers to another meaning.

[0043] In this document, "or its combination" means "or any combination thereof", and "any one", "any one" means "any one", "any one" or "any one".

[0044] In this article, the terms "comprise", "include", "have", "contain" or any other similar terms are open-ended transitional phrases, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed in this article, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), A and B are both true (or exist). In addition, in this article, the interpretation of the terms "comprise", "include", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed transitional phrases such as "consisting of", "consisting of", "the balance is", and "substantially consisting of", "mainly consisting of", "mainly consisting of", "basically containing", "basically consisting of", "basically consisting of", "essentially containing" and other transitional phrases.

[0045] In this article, all features or conditions such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible sub-ranges and individual values ​​within the range (including integers and fractions), especially integer values. For example, the range description of "1.0 to 8.0" or "between 1.0 and 8.0" or "between 1.0 and 8.0" should be deemed to have specifically disclosed all sub-ranges such as 1.0 to 8.0, 1.0 to 7.0, 2.0 to 8.0, 2.0 to 6.0, 3.0 to 6.0, 4.0 to 8.0, 3.0 to 8.0, etc., and should be deemed to cover endpoint values, especially sub-ranges defined by integer values, and should be deemed to have specifically disclosed individual values ​​such as 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, etc. Unless otherwise indicated, the foregoing method of interpretation applies to all contents of the entire application, regardless of whether the scope is broad or not.

[0046] If the quantity, concentration or other numerical value or parameter is expressed as a range, a preferred range (or a better range) or a series of upper and lower limits, it should be understood that all ranges consisting of any pair of the upper limit or preferred value (or a better value) of the range and the lower limit or preferred value (or a better value) of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0047] In this document, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range of 39.50 to 40.49.

[0048] In this article, for the use of Markush groups or optional terms to describe the features or examples of the present application, those skilled in the art should understand that all subgroups or any individual elements in the Markush group or option list can also be used to describe the present application. For example, if X is described as "selected from the group consisting of X1, X2 and X3", it also means that the claim that X is X1 and the claim that X is X1 and / or X2 and / or X3 have been fully described. Furthermore, for the use of Markush groups or optional terms to describe the features or examples of the present application, those skilled in the art should understand that any combination of subgroups or individual members of all elements in the Markush group or option list can also be used to describe the present application. Accordingly, for example, if X is described as "selected from the group consisting of X1, X2 and X3", and Y is described as "selected from the group consisting of Y1, Y2 and Y3", it means that the claim that X is X1 and / or X2 and / or X3 and Y is Y1 and / or Y2 and / or Y3 has been fully described.

[0049] Unless otherwise specified, in this application, a compound refers to a chemical substance formed by two or more elements connected by chemical bonds, including small molecule compounds and polymer compounds, but not limited thereto. The interpretation of a compound in this article is not limited to a single chemical substance, but can also be interpreted as the same type of chemical substances with the same composition or the same properties.

[0050] If not otherwise specified, in this application, polymer refers to the product formed by monomer polymerization, often including many polymer aggregates, each polymer is composed of many simple structural units repeatedly connected by covalent bonds, and the monomer is a compound of synthetic polymer. Polymers can include homopolymers, copolymers, prepolymers, etc., and are not limited to this. Homopolymers refer to polymers polymerized from a monomer. Copolymers include random copolymers (structures such as -AABABBBAAABBA-), alternating copolymers (structures such as -ABABABAB-), graft copolymers (structures such as -AA (A-BBBB) AA (A-BBBB) AAA-) and block copolymers (structures such as -AAAAA-BBBBBB-AAAAA-), etc. Prepolymers refer to a polymer with a lower molecular weight between the monomer and the final polymer, and the prepolymer contains reactive functional groups that can be further polymerized to obtain a fully cross-linked or hardened higher molecular weight product. Polymers certainly include oligomers, and are not limited to this. Oligomers, also known as low polymers, are polymers composed of 2 to 20 repeating units, usually 2 to 5 repeating units.

[0051] Unless otherwise specified, the "resin" in this application is a customary name for a synthetic polymer, which may include monomers, polymers thereof, combinations of monomers, combinations of polymers thereof, or combinations of monomers and polymers thereof, etc., and is not limited thereto.

[0052] If not otherwise specified, in the present application, modified products include products after modification of reactive functional groups of each resin, products after prepolymerization of each resin with other resins, products after crosslinking of each resin with other resins, products after copolymerization of each resin with other resins, and the like.

[0053] If not otherwise specified, the unsaturated bonds described in the present application refer to reactive unsaturated bonds, such as but not limited to unsaturated double bonds that can undergo cross-linking reactions with other functional groups, such as but not limited to unsaturated carbon-carbon double bonds that can undergo cross-linking reactions with other functional groups.

[0054] The unsaturated carbon-carbon double bonds described in the present application preferably include, but are not limited to, vinyl, vinylbenzyl, (meth)acryloyl, allyl or a combination thereof. Vinyl should include vinyl and vinylidene when interpreted. (Meth)acryloyl should include acryloyl and methacryloyl when interpreted.

[0055] Unless otherwise specified, the hydrocarbon groups described in this application include, but are not limited to, alkyl, alkenyl or alkynyl, and include their various isomers when interpreted. For example, a C1-C6 divalent hydrocarbon group is interpreted to include a C1-C6 divalent straight-chain hydrocarbon group, a C2-C6 divalent branched hydrocarbon group or a C3-C6 divalent cyclic hydrocarbon group. For another example, a propyl group should be interpreted to include n-propyl and isopropyl.

[0056] Unless otherwise specified, in this application, parts by weight represent relative parts by weight in a composition, which may be any weight unit, such as but not limited to kilograms, kilograms, grams, pounds, etc. For example, 100 parts by weight of polyphenylene ether resin may represent 100 kilograms of polyphenylene ether resin or 100 pounds of polyphenylene ether resin.

[0057] It should be understood that the features disclosed in the various embodiments herein may be arbitrarily combined to form the technical solution of the present application, as long as there is no contradiction in the combination of these features.

[0058] The present application will be described below with specific implementations and examples. It should be understood that these specific implementations and examples are merely illustrative and are not intended to limit the scope of the present application and its use.

[0059] Unless otherwise stated, the methods, reagents and conditions used in the following preparation examples, comparative examples and examples are conventional methods, reagents and conditions in the art.

[0060] In the following descriptions: LCP resin: active ingredient content ≥99.99%, density 1400kg / m³, heat deformation temperature 280℃, processing temperature 150~270℃; Microwave electrothermal analyzer: purchased from AET Company, Japan.

[0061] Example Example 1 The preparation method of this embodiment includes: S1, heating, melting, and plasticizing the LCP resin through an extruder, and then extruding it through a T-shaped structure forming die and cooling it at 15° C. to obtain a first film; S2.1. Laminate the two first films by a film laminator at a laminating temperature of 160°C; introduce the two laminated first films into a stretching box for stretching; the O3 concentration in the stretching box is 0.01 mol / m 3 , the stretching temperature is 200°C to obtain a stretched film; S2.2, separating the stretched films and cooling them at 15°C, then rinsing them with deionized water and air-drying them at 15°C to obtain two second films; S3, pulling, trimming and winding the second film in sequence to obtain an LCP film.

[0062] Example 2 The difference between this embodiment and embodiment 1 is that the concentration of O3 in step S2.1 of this embodiment is 0.05 mol / m 3 .

[0063] Example 3 The difference between this embodiment and embodiment 1 is that the concentration of O3 in step S2.1 of this embodiment is 0.1 mol / m 3 .

[0064] Example 4 Reference Figure 1 The difference between this embodiment and embodiment 1 is that the concentration of O3 in the stretching box in step S2.1 of this embodiment is 0.01 mol / m 3 , the stretching temperature is 200℃, and the UV irradiation intensity is 2000μW / cm 2 Attached Figure 1 The direction indicated by the arrow is the movement direction of the film.

[0065] Example 5 The difference between this embodiment and embodiment 4 is that the irradiation intensity of the ultraviolet rays in the stretching box in step S2.1 of this embodiment is 1250 μW / cm 2 .

[0066] Example 6 The difference between this embodiment and embodiment 4 is that the irradiation intensity of the ultraviolet rays in the stretching box in step S2.1 of this embodiment is 500 μW / cm 2 .

[0067] Example 7 The difference between this embodiment and embodiment 1 is that the stretching temperature in step S2.1 of this embodiment is 250°C.

[0068] Example 8 The difference between this embodiment and embodiment 1 is that in step S2.2 of this embodiment, the stretched films are separated and cooled at 15°C, and then both are cleaned with 5g / LNaOH ethanol solution, rinsed with deionized water, and air-dried at 15°C to obtain two second films.

[0069] Comparative Example Comparative Example 1 The preparation method of this comparative example comprises: S1, heating, melting, and plasticizing the LCP resin through an extruder, and then extruding it through a T-shaped structure forming die and cooling it at 15° C. to obtain a first film; S2.1. The first film is introduced into a stretching box for stretching. The stretching temperature is 200°C and the irradiation intensity of ultraviolet light in the stretching box is 2000 μW / cm 2 , obtaining a stretched film; S2.2, cooling the stretched film at 15° C., then washing with deionized water and air-drying at 15° C. to obtain a second film; S3, pulling, trimming and winding the second film in sequence to obtain an LCP film.

[0070] Comparative Example 2 The preparation method of this comparative example comprises: S1, heating, melting, and plasticizing the LCP resin through an extruder, and then extruding it through a T-shaped structure forming die and cooling it at 15° C. to obtain a first film; S2.1. The first film is introduced into a stretching box for stretching. The stretching temperature is 200°C and the irradiation intensity of ultraviolet light in the stretching box is 20000 μW / cm 2 , obtaining a stretched film; S2.2, cooling the stretched film at 15°C, then soaking it in a 50 g / L NaOH aqueous solution for 2 min, rinsing it with deionized water, and air-drying it at 15°C to obtain a second film; S3, pulling, trimming and winding the second film in sequence to obtain an LCP film.

[0071] Performance Testing The LCP films prepared in Examples 1 to 8 and Comparative Examples 1 to 2 were tested according to the following test items: (1) Tensile strength: Tested according to GB / T 1040.3-2006 method, unit: MPa; (2) Peel strength: The LCP film and the copper foil with a surface roughness of 0.706 μm were hot pressed and then tested according to GBT 2791-1995. Unit: N / cm; (3) Dimensional change rate: Tested according to the method of JIS C 6471-1995 9.6. Specifically, a 300 mm*300 mm film is cut and 4 points are marked according to the standard requirements and the distance between each point is measured. The film is then placed in an oven at 150°C for 30 minutes, and the distance between the 4 points is measured again to calculate the dimensional change rate (unit: %). (4) Dielectric constant (Dk) and dielectric loss (Df): The LCP film was heat-pressed with a copper foil having a surface roughness of 0.706 μm. The dielectric constant and dielectric loss were measured at a frequency of 10 GHz according to the method described in JIS C 2565. The lower the dielectric constant and dielectric loss, the better the dielectric properties of the sample.

[0072] Test Results According to Table 1 above, by comparing Example 1 and Comparative Example 1, it can be seen that the peel strength of the LCP film obtained in Example 1 is better than that of Comparative Example 1. The possible reason is that during the stretching process, O3 causes new groups to appear on the surface of the LCP film and the roughness to increase, thereby improving the bonding strength between the LCP film and the copper foil.

[0073] By comparing Example 1 and Comparative Example 2, it is obviously found that when the bonding force between the LCP film and the copper foil is close, the tensile strength, dimensional change rate and dielectric properties of the LCP film obtained in Example 1 are better than those in Comparative Example 2. This may be because the preparation method in Example 1 only changes the properties of one side of the LCP film without affecting the regularity of the LCP film molecules, thereby being able to maintain the performance of the LCP film.

[0074] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, some simple deductions or substitutions can be made without departing from the concept of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for producing an LCP film, characterized in that: The steps include: S1, melting LCP, extruding it through a forming die, and cooling it to obtain a first film; S2, laminating the two first films and stretching them in an environment containing a processing gas, and then separating the two laminated first films to obtain two second films; S3, pulling, trimming, and rolling up the second film in sequence to obtain an LCP film; The processing gas has one or more properties of acidity, corrosiveness, and oxidation to the first film.

2. The method for producing a LCP film according to claim 1, characterized in that: The processing gas is selected from one or more of HCl, O2, O3, and Cl2.

3. The method for producing a LCP film according to claim 1, characterized in that: The concentration of the treatment gas is 0.01 mol / m 3 ~0.1mol / m 3 .

4. The method for producing a LCP film according to claim 1, characterized in that: In the step S2, the two first films bonded together are separated and then cleaned with an alkaline alcohol solution, rinsed with deionized water, and dried to obtain two second films.

5. The method for producing a LCP film according to claim 4, characterized in that: The alcoholic base solution comprises a strong base and an alcohol; And / or, the concentration of the alkali alcohol solution is 5-10 g / L.

6. The method for producing a LCP film according to claim 1, characterized in that: In the step S2, after the two first films are bonded together, they are irradiated with ultraviolet rays during the stretching process.

7. The method for producing a LCP film according to claim 7, characterized in that: The irradiation intensity of the ultraviolet light is 500 to 2000 μW / cm 2 .

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