Liquid crystal polymer film and laminate containing the liquid crystal polymer film

Abstract

To provide: a liquid crystal polymer (LCP) film satisfying improvement in the peel strength between metal foil and the LCP film and ensured low insertion loss of a laminate; and a laminate comprising the same.SOLUTION: An LCP film has a first surface and a second surface opposite each other, and a kurtosis (Rku) of the first surface ranges from 3.0 to 60.0. With the Rku, the LCP film is able to improve the peel strength between metal foil and the LCP film and ensure that a laminate comprising the same material maintains the advantage of low insertion loss.SELECTED DRAWING: None

Description

Technical Field

[0001] This application relates to a polymer film for a laminate, more specifically, a liquid crystal polymer (LCP) film and a laminate including the polymer film.

Background Art

[0002] Due to the rapid development of mobile communication technologies, the telecommunications industry is forced to actively develop the fifth-generation mobile network (abbreviated as 5G) in order to optimize the performance such as the data transmission speed, response time, and system capacity of the fourth-generation mobile network (4G).

[0003] Since 5G communication technology uses a high-frequency band for signal transmission, the higher the signal frequency, the greater the insertion loss. In order to achieve signal transmission using a high-frequency band, an LCP film with low hygroscopicity and low dielectric properties is selected as a substitute for a hygroscopic and high-dielectric property polyimide film (PI film), and stacked with a metal foil to manufacture a laminate, and it is known that the insertion loss at high frequencies can be reduced.

[0004] However, the interfacial adhesion between the LCP film and the metal foil of the laminate is generally insufficient, and the components on the circuit board are likely to detach, so that the subsequent lamination process is seriously affected. With the progress of technology, the reduction of the insertion loss of the laminate is also eagerly desired. Therefore, the problems of insufficient peel strength and large insertion loss between the conventional LCP film and the metal foil of the laminate still need to be solved.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Considering the above issues, the object of this application is to enhance the peel strength between the LCP film and the metal foil, and to ensure low insertion loss in the laminate. [Means for solving the problem]

[0007] To achieve the above objective, one aspect of this application provides an LCP film. This LCP film has a first surface and a second surface that are opposite to each other, and the kurtosis (Rku) of the first surface is 3.0 or greater and 60.0 or less.

[0008] By controlling the Rku properties of the first surface of the LCP film, the adhesion of the LCP film stacked on the metal foil is increased, thereby strengthening the peel strength between the LCP film and the metal foil, and further preventing problems such as wire separation during subsequent lamination. Moreover, the above technical means ensure that the laminate containing such an LCP film has low insertion loss.

[0009] In one embodiment, in addition to the first surface of the LCP film, the Rku of the second surface may also be 3.0 or greater and 60.0 or less. Therefore, regardless of whether the LCP film of this application is laminated to at least one metal foil on either the first surface and the second surface or both, the LCP film has excellent adhesion to at least one metal foil, thereby enhancing the peel strength between the LCP film and at least one metal foil under conditions where the laminate has low insertion loss.

[0010] In other words, by applying the LCP film of this application to a laminate, the laminate becomes particularly suitable for high-end 5G products.

[0011] Preferably, the Rku of the first surface of the LCP film of this application may be 3.4 or more and 60.0 or less. In one embodiment, the Rku of the first surface of the LCP film of this application may be 3.4 or more and 59.9 or less. In one embodiment, both the Rku of the first surface and the Rku of the second surface of the LCP film of this application may fall within any of the above ranges. The Rku of the first surface and the Rku of the second surface of the LCP film of this application may be the same or different, as necessary. In one embodiment, the Rku of the first surface and the Rku of the second surface of the LCP film of this application are different.

[0012] Preferably, the arithmetic mean roughness (Ra) of the first surface of the LCP film of this application may be 0.09 micrometers (μm) or less. Here, in addition to achieving high peel strength between the LCP film and the metal foil, applying the LCP film to the laminate further reduces insertion loss, and therefore the laminate containing the LCP film is very suitable for high-end 5G products. More preferably, the Ra of the first surface of the LCP film of this application may be 0.02 μm or more and 0.09 μm or less, and even more preferably, the Ra of the first surface may be 0.020 μm or more and 0.088 μm or less. By reducing the Ra of the first surface of the LCP film, the insertion loss of the laminate containing the LCP film is further reduced, and as a result the laminate is very suitable for high-end 5G products. In one embodiment, the Ra of the first surface of the LCP film of this application may be 0.04 μm or more and 0.09 μm or less. In one embodiment, both the Ra of the first surface and the Ra of the second surface of the LCP film of this application may fall within any of the above ranges. The Ra of the first surface and the Ra of the second surface of the LCP film of this application may be the same or different as needed. In one embodiment, the Ra of the first surface and the Ra of the second surface of the LCP film of this application are different.

[0013] Preferably, the ten-point average roughness (Rz) of the first surface of the LCP film may be 2.0 μm or less, and more preferably, the Rz of the first surface of the LCP film of this application may be 1.9 μm or less. In one embodiment, the Rz of the first surface of the LCP film of this application may be 0.1 μm or more and 2.0 μm or less. Preferably, the Rz of the first surface of the LCP film of this application may be 0.2 μm or more and 2.0 μm or less, and more preferably, the Rz of the first surface of the LCP film of this application may be 0.3 μm or more and 2.0 μm or less. Even more preferably, the Rz of the first surface of the LCP film of this application may be 0.3 μm or more and 1.9 μm or less. In one embodiment, both the Rz of the first surface and the Rz of the second surface of the LCP film of this application may fall within any of the above ranges. The Rz of the first surface and the Rz of the second surface of the LCP film of this application may be the same or different, as necessary. In one embodiment, the Rz of the first surface and the Rz of the second surface of the LCP film of this application are different.

[0014] According to this application, the LCP film may be manufactured from an LCP resin, which is commercially available or manufactured from conventional raw materials. The LCP resin is not particularly limited in this application. For example, LCP resin may be prepared using aromatic or aliphatic hydroxy compounds, such as hydroquinone, resorcinol, 2,6-naphthalenediol, ethanediol, 1,4-butanediol, and 1,6-hexanediol; aromatic or aliphatic dicarboxylic acids, such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2-chloroterephthalic acid, and adipic acid; aromatic hydroxycarboxylic acids, such as 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, and 4'-hydroxy-4-biphenylcarboxylic acid; aromatic amine compounds, such as p-phenylenediamine, 4,4'-diaminobiphenyl, naphthalene-2,6-diamine, 4-aminophenol, 4-amino-3-methylphenol, and 4-aminobenzoic acid, as raw materials, and then the LCP film of this application may be prepared using the LCP resin. In one embodiment of this application, 6-hydroxy-2-naphthalenecarboxylic acid, 4-hydroxybenzoic acid, and acetyl anhydride (also called acetic anhydride) may be selected to obtain an LCP resin, and the LCP film of this application can be prepared using the LCP resin. In one embodiment, the melting point of the LCP resin may be about 250°C to 360°C.

[0015] In one embodiment, those skilled in the art may add, as needed, additives such as lubricants, antioxidants, electrical insulators, or fillers during the preparation of the LCP film of this application. For example, applicable additives may include, but are not limited to, polycarbonate, polyamide, polyphenylene sulfide, or polyether ether ketone.

[0016] According to this application, the thickness of the LCP film is not particularly limited. For example, the thickness of the LCP film may be 10 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less. More preferably 15 μm or more and 250 μm or less, and even more preferably 20 μm or more and 200 μm or less.

[0017] To achieve the above objective, another aspect of this application also provides a laminate comprising a first metal foil and an LCP film. The first metal foil is placed on a first surface of the LCP film. That is, the first metal foil of the laminate of this application is stacked on top of the first surface of the LCP film.

[0018] In one embodiment, the laminate of the present application may further include a second metal foil, which is arranged on a second surface of the LCP film. That is, the first metal foil of the laminate of the present application is stacked on the first surface of the LCP film, and the second metal foil of the laminate is stacked on the second surface of the LCP film. In this embodiment, when the Rku properties of both the first and second surfaces of the LCP film are controlled simultaneously, both the adhesion of the LCP film stacked on the first metal foil and the adhesion of the LCP film stacked on the second metal foil are improved. Therefore, both the peel strength between the LCP film and the first metal foil and the peel strength between the LCP film and the second metal foil are enhanced. At the same time, a low insertion loss of the laminate is achieved.

[0019] According to this application, "stacking" is not limited to direct contact, but also includes indirect contact. For example, in one embodiment of this application, the first metal foil of the laminate is stacked in indirect contact with the first surface of the LCP film. In another embodiment of this application, the first metal foil of the laminate is stacked in indirect contact with the first surface of the LCP film. Specifically, a connecting layer may be placed between the first metal foil and the first surface of the LCP film as needed, so that the first metal foil contacts the first surface of the LCP film via the connecting layer. The material of the connecting layer may be adjusted according to the specific requirements. For example, the material of the connecting layer may be nickel, cobalt, chromium, or alloys thereof, which provide functions such as heat resistance, chemical resistance, or electrical resistance. Similarly, the second metal foil of the laminate may be stacked in direct or indirect contact with the second surface of the LCP film. In one embodiment of this application, the stacking method of the LCP film and the first metal foil may be the same as the stacking method of the LCP film and the second metal foil. In another embodiment, the stacking method of the LCP film and the first metal foil may be different from the stacking method of the LCP film and the second metal foil.

[0020] According to the present application, the first metal foil and / or the second metal foil may be, but are not limited to, copper foil, gold foil, silver foil, nickel foil, aluminum foil, stainless steel foil, etc. In one embodiment, the first metal foil and the second metal foil may be made of different materials. Preferably, the first metal foil and / or the second metal foil may be copper foil, and as a result, a copper-clad laminate (CCL) is formed by laminating the copper foil and the LCP film. In addition, the method for preparing the first metal foil and / or the second metal foil is not particularly limited as long as the method does not contravene the purpose of the present application. For example, the metal foil may be manufactured, but is not limited to, by a roll-to-roll method or an electrodeposition method.

[0021] According to the present application, the thicknesses of the first metal foil and / or the second metal foil are not particularly limited and can be adjusted by those skilled in the art according to their respective needs. For example, in one embodiment, the thicknesses of the first metal foil and / or the second metal foil may independently be 1 μm or more and 200 μm or less, preferably, the thicknesses of the first metal foil and / or the second metal foil may independently be 1 μm or more and 4 μm or less. More preferably, the thicknesses of the first metal foil and / or the second metal foil may independently be 1 μm or more and 20 μm or less, and even more preferably, the thicknesses of the first metal foil and / or the second metal foil may independently be 3 μm or more and 20 μm or less.

[0022] According to the present application, the surface treatment of the first metal foil and / or the second metal foil of the present application can be carried out by those skilled in the art according to their respective needs, For example, the surface treatment may be selected from, but is not limited to, roughening treatment, acid-base treatment, heat treatment, degreasing treatment, ultraviolet irradiation treatment, corona discharge treatment, plasma treatment, primer coating treatment, etc.

[0023] According to the present application, the roughness of the first metal foil and / or the second metal foil is not particularly restricted and can be adjusted by those skilled in the art according to their respective requirements. In one embodiment, the Rz of the first metal foil and / or the Rz of the second metal foil may independently be 0.1 μm or more and 2.0 μm or less, and preferably, the Rz of the first metal foil and / or the Rz of the second metal foil may independently be 0.1 μm or more and 1.5 μm or less. In one embodiment, the Rz of the first metal foil and the Rz of the second metal foil may both fall within any of the above ranges. The Rz of the first metal foil and the Rz of the second metal foil may be the same or different as required. In one embodiment, the Rz of the first metal foil and the Rz of the second metal foil are different.

[0024] In one embodiment, a third metal foil may additionally be provided by those skilled in the art based on their respective requirements. The third metal foil may be the same as or different from the first metal foil and / or the second metal foil as required. In one embodiment, the Rz of the third metal foil may fall within any of the ranges of the Rz of the first metal foil and / or the Rz of the second metal foil described above. In one embodiment, the Rz of the first metal foil, the Rz of the second metal foil, and the Rz of the third metal foil are different.

[0025] Preferably, the first metal foil, the second metal foil, and / or the third metal foil may be a low-profile metal foil, for example, a low-profile copper foil.

[0026] In one embodiment, the laminate may include a plurality of LCP films. On the premise that it does not contravene the gist of the present application, the plurality of LCP films and the plurality of metal foils (for example, the first metal foil, the second metal foil, and / or the third metal foil described above) can be stacked by those skilled in the art according to their respective requirements, and a laminate having the plurality of LCP films and the plurality of metal foils can be manufactured.

[0027] In this specification, the term "skewness (Rku)" is defined according to JIS B 0601:2001, and the "arithmetic mean roughness (Ra)" and the "ten-point mean roughness (Rz)" are defined according to JIS B 0601:1994. [Modes for carrying out the invention]

[0028] The following examples illustrate the raw materials used in the manufacture of the LCP film of this application. Further examples are provided to illustrate the implementation of the LCP film and laminate of this application, and several comparative examples are provided for comparison. Those skilled in the art will readily recognize the advantages and effects of this application from the following examples and comparative examples. The descriptions proposed herein are merely illustrative preferred embodiments and are not intended to limit the scope of this application. Various modifications and changes can be made without departing from the spirit and scope of this application in order to carry out or apply this application.

[0029] 《LCP resin》 Preparation example 1: LCP resin A mixture of 6-hydroxy-2-naphthalenecarboxylic acid (540 g), 4-hydroxybenzoic acid (1071 g), acetyl anhydride (1086 g), sodium phosphite (1.3 g), and 1-methylimidazole (0.3 g) was placed in a 3 L autoclave and stirred at 160°C for approximately 2 hours under atmospheric pressure and a nitrogen atmosphere for acetylation. The mixture was then heated to 320°C at a rate of 30°C / hour, and then, under these temperature conditions, the pressure was slowly reduced from 760 Torrell to less than 3 Torrell, while the temperature was increased from 320°C to 340°C. Subsequently, the powder was stirred, the pressure was increased, and steps were carried out to discharge the polymer, pull the strands, and cut the strands into pellets to obtain an LCP resin having a melting point of approximately 278°C and a viscosity of approximately 45 Pa·s (@300°C).

[0030] Preparation example 2: LCP resin A mixture of 6-hydroxy-2-naphthalenecarboxylic acid (440g), 4-hydroxybenzoic acid (1145g), acetyl anhydride (1085g), and sodium phosphite (1.3g) was placed in a 3L autoclave and stirred at 160°C for approximately 2 hours under atmospheric pressure and a nitrogen atmosphere for acetylation. The mixture was then heated to 320°C at a rate of 30°C / hour, and then, under these temperature conditions, the pressure was slowly reduced from 760 Torrell to less than 3 Torrell, while the temperature was increased from 320°C to 340°C. Subsequently, the powder was stirred, the pressure was increased, and steps were carried out to discharge the polymer, pull the strands, and cut the strands into pellets to obtain an LCP resin having a melting point of approximately 305°C and a viscosity of approximately 40 Pa·s (@300°C).

[0031] LCP film Examples 1-12 and Comparative Examples 1-6: LCP film Using the LCP resins (PE1 and PE2) obtained from Preparation Examples 1 and 2 as raw materials, LCP films for Examples 1 to 12 (E1 to E12) and Comparative Examples 1 to 6 (C1 to C6) were prepared by the following method.

[0032] First, the LCP resin was placed in an extruder (manufacturer: Leistritz, model: ZSE27) with a screw diameter of 27 mm, heated to a temperature in the range of 300°C to 320°C, and then extruded through a 500 mm wide T-die at a feed rate in the range of 5.5 kg / hour to 8.5 kg / hour. Next, the LCP resin was fed into the space between two casting wheels (the wheels being approximately 5 mm to 20 mm away from the T-die, each having a temperature in the range of approximately 290°C to 330°C and a diameter in the range of approximately 35 cm to 45 cm), extruded with a force of approximately 20 kilonewtons (kN) to 60 kN, and then transferred to a cooling wheel to cool at room temperature to obtain an LCP film having a thickness of 50 μm.

[0033] The processes in Examples 1-12 differ from those in Comparative Examples 1-6 in the type of LCP resin, the distance from the T-die to the casting wheel surface, the feed rate, and the extrusion temperature. The parameters for Examples 1-12 and Comparative Examples 1-6 are listed in Table 1 below.

[0034] [Table 1]

[0035] The above-described method for preparing LCP film is for illustrative purposes only. Those skilled in the art may prepare LCP film using conventional methods such as lamination extrusion and inflation.

[0036] In one embodiment, after extruding the LCP resin from a T-die, the LCP resin is fed together with two high-temperature resistant films into the space between two casting wheels, and a three-layer laminate can be formed as needed by those skilled in the art. The two high-temperature resistant films are separated from the LCP resin at room temperature to obtain the LCP film of this application. The high-temperature resistant films may be selected from, but are not limited to, poly(tetrafluoroethene) (PTFE) films, polyimide (PI) films, and poly(ethersulfone) (PES) films.

[0037] Furthermore, post-treatment of the obtained LCP film may be carried out by those skilled in the art as needed. Post-treatments include, but are not limited to, polishing, ultraviolet irradiation, and plasma. Plasma treatment may be applied with a 1-kilowatt (kW) plasma under reduced pressure or atmospheric pressure in a nitrogen, oxygen, or air atmosphere, depending on the needs, but is not limited to these.

[0038] Test Example 1: Rku, Ra, and Rz of LCP film In this test example, LCP films from Examples 1-12 and Comparative Examples 1-6 were used as test samples. The Rku of the surface of each test sample was measured according to JIS B 0601:2001, and the Ra and Rz of the surface of each test sample were measured according to JIS B 0601:1994.

[0039] To measure the Rku, Ra, and Rz of any surface of each test sample, a confocal laser scanning microscope (manufacturer: Olympus, model: LEXT OLS5000-SAF, objective lens: MPLAPON-50xLEXT) was used with objective lenses with optical zoom of 50X and 1X magnification, and a light source with a wavelength of 405 nanometers (nm), at a temperature of 24±3℃ and humidity of 63±3%, to capture surface morphological images of the test samples. The Rku of the test samples was measured using a 4mm evaluation length, a high-pass filter with a cutoff value (λc) of 0.8mm, a low-pass filter with a cutoff value (λs) of 2.5μm, a resolution of 1024 pixels × 1024 pixels, and automatic tilt removal mode. The Ra and Rz of the test samples were measured using a 4mm evaluation length and a cutoff value of 0.8mm.

[0040] According to the method described above, the Rku, Ra, and Rz results for the surface of any of the LCP films in Examples 1-12 and Comparative Examples 1-6 are shown in Table 2 below.

[0041] Examples 1A-12A and Comparative Examples 1A-6A: Laminates The laminates of Examples 1A to 12A (E1A to E12A) and Comparative Examples 1A to 6A (C1A to C6A) were manufactured from the laminates of Examples 1 to 12 and Comparative Examples 1 to 6, respectively, which were stacked on commercially available copper foil.

[0042] The following is a product description of commercially available copper foil. Copper foil 1: CF-T49A-HD2, purchased from Fukuda Metal Foil Powder Industry Co., Ltd., Rz: approx. 1.2 μm Copper foil 2: CF-H9A-HD2, purchased from Fukuda Metal Foil Powder Industry Co., Ltd., Rz: approx. 1.0 μm

[0043] Table 2 shows the types of LCP film and copper foil used in each of the laminates of Examples 1A to 12A and Comparative Examples 1A to 6A. Each of the laminates was manufactured as follows.

[0044] An LCP film with a thickness of approximately 50 μm and two identical copper foils, each approximately 12 μm thick, were first cut to a size of 20 cm x 20 cm. Next, the LCP film was sandwiched between the two commercially available copper foils to form a laminated structure. This laminated structure was subjected to a load of 5 kilograms per square centimeter (kg / cm²). 2 ) at a pressure of 180°C for 60 seconds, followed by 20 kg / cm². 2 The material was processed at 300°C for 25 minutes (min) under pressure, and then cooled to room temperature to obtain a laminate.

[0045] Here, the method of lamination of the laminate is not particularly limited. Those skilled in the art may carry out the lamination process using conventional techniques such as wire lamination or surface lamination. Laminators applicable to this application may be, but are not limited to, intermittent hot presses, roll-to-roll wheel machines, double belt presses, etc. Depending on the requirements, those skilled in the art may align LCP film with copper foil to form a laminated structure, which may then be processed by surface lamination including a heating step and a pressing step.

[0046] In another embodiment, a metal foil, such as copper foil, on the LCP film may be formed by sputtering, electroplating, chemical plating, vapor deposition, or the like, as required by those skilled in the art. Alternatively, a connecting layer, such as a glue layer, nickel layer, cobalt layer, chromium layer, or an alloy thereof, may be formed between the LCP film and the metal foil, as required by those skilled in the art.

[0047] Test Example 2: Peel Strength of Laminates The peel strength of the laminates was measured according to IPC-TM-650 No:2.4.9. The laminates of Examples 1A-12A and Comparative Examples 1A-6A were each cut into etched test specimens approximately 228.6 mm in length and 3.2 mm in width. Each etched test specimen was stabilized by placing it at a temperature of 23±2°C and a relative humidity of 50±5% for 24 hours. Then, each etched test specimen was attached to the clamp of the testing machine (manufacturer: Hung Ta Instrument Co., Ltd., model: HT-9102) with double-sided adhesive tape. Each etched test specimen was then peeled from the clamp with a predetermined force at a peeling speed of 50.8 mm / min, and the force value during the peeling process was continuously recorded. Here, the force had to be controlled within the range of 15% to 85% of the test machine's yield strength, the peeling distance from the clamp had to be at least 57.2 mm, and the force up to the initial distance of 6.4 mm was ignored and not recorded. The results are shown in Table 2.

[0048] Test Example 3: Insertion Loss of Laminates The laminates of Examples 1A-12A and Comparative Examples 1A-6A were each cut into strip test specimens approximately 100 mm in length, 140 mm in width, and with a resistance of approximately 50 ohms (Ω). The insertion loss of the strip test specimens was measured at 10 GHz using a microwave network analyzer (manufacturer: Agilent Technologies, Ltd., model: 8722ES) including a probe (manufacturer: Cascade Microtech, model: ACP40-250). The results for the laminates are shown in Table 2 below.

[0049] [Table 2]

[0050] Analysis of test results By comparing the results of the above laminate with those of a laminate having the same type of copper foil, the influence of the LCP film on the performance of the laminate was clarified. As a result, those skilled in the art will understand that the beneficial effect of the laminate is due to the LCP film, and that the LCP film is useful for optimizing the performance of the laminate.

[0051] As shown in Table 2 above, the Rku of any surface of the LCP films in Examples 1 to 12 was controlled to be within the range of 3.0 or higher and 60.0 or lower. As a result, the laminates of Examples 1A to 12A (made from such LCP films and various commercially available copper foils) all exhibited high peel strength and low insertion loss. In contrast, the Rku of any surface of each of the LCP films in Comparative Examples 1 to 6 was outside the above range, and as a result, the laminates of Comparative Examples 1A to 6A did not have high peel strength and low insertion loss.

[0052] The results of multiple laminates having copper foil 1 were compared and analyzed. When the Rku of the LCP film (e.g., Comparative Example 1) exceeded 60.0, the manufactured laminate (e.g., Comparative Example 1A) exhibited large insertion loss. On the other hand, when the Rku of the LCP film (e.g., Comparative Example 2) was less than 3.0, the manufactured laminate (e.g., Comparative Example 2A) had clearly insufficient peel strength. In contrast, when the Rku of the LCP film (e.g., Examples 1-6) was controlled to be between 3.0 and 60.0, the laminate (e.g., Examples 1A-6A) not only showed improved peel strength between the LCP film and the metal foil, but also exhibited low insertion loss.

[0053] Even when different copper foils were used, the LCP film of this application still provided improved peel strength and a laminate with low insertion loss. Specifically, the results of several laminates having copper foil 2 were compared and analyzed. Compared with the results of laminates that did not use the claimed LCP film (e.g., Comparative Examples 3A-6A), LCP films having an Rku in the range of 3.0-60.0 (e.g., Examples 7-12) showed improved peel strength and low insertion loss when laminated (e.g., Examples 7A-12A).

[0054] In summary, by controlling the Rku of the first surface of the LCP film to be between 3.0 and 60.0, the laminate not only improves the peel strength between the LCP film and the metal foil, but also exhibits low insertion loss. Therefore, the laminate of this application is highly suitable for high-end 5G products.

[0055] Many of the features and advantages of this application have been described above, along with details of its structure and features, but this disclosure is illustrative only. Within the principles of this application, modifications to the details may be made, in particular with respect to shape, size, and arrangement of parts, to the extent that the broader meaning of the terms expressed in the appended claims indicates.

Claims

1. Including a first surface and a second surface that are opposite to each other, The kurtosis (Rku) of the first surface is 3.0 or greater and 60.0 or less. The aforementioned kurtosis is defined by JIS B 0601:2001, The ten-point average roughness of the first surface is 0.1 μm or more and 2.0 μm or less, and the ten-point average roughness is defined according to JIS B 0601:1994. The arithmetic mean roughness of the first surface is 0.09 μm or less, and the arithmetic mean roughness is defined according to JIS B 0601:1994. Liquid crystal polymer film used in laminates.

2. The liquid crystal polymer film according to claim 1, characterized in that the Rku of the first surface is 3.4 or more and 60.0 or less.

3. The liquid crystal polymer film according to claim 1, characterized in that the arithmetic mean roughness of the first surface is 0.02 μm or more and 0.09 μm or less.

4. The liquid crystal polymer film according to any one of claims 1 to 3, characterized in that the Rku of the second surface is 3.0 or more and 60.0 or less.

5. The liquid crystal polymer film according to any one of claims 1 to 4, characterized in that the arithmetic mean roughness of the second surface is 0.09 μm or less.

6. The liquid crystal polymer film according to any one of claims 1 to 5, characterized in that the ten-point average roughness of the second surface is 2.0 μm or less.

7. A laminate comprising a first metal foil and a liquid crystal polymer film according to any one of claims 1 to 6, The first metal foil is disposed on the first surface of the liquid crystal polymer film. Laminated structure.

8. The laminate according to claim 7, characterized in that the laminate includes a second metal foil, the second metal foil being arranged on the second surface of the liquid crystal polymer film.

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