Liquid crystal polymer film and its uses

Abstract

A liquid crystal polymer film having a low dielectric constant and a low dielectric loss tangent, and a metal clad laminate and a printed circuit board including the same are provided. The liquid crystal polymer film has a heat of fusion of 0.50 J / g to 1.10 J / g and has a first surface and a second surface opposite to the first surface. The ratio of the root mean square height to the arithmetic mean height (Sq / Sa) of the first surface is 1.20 to 2.30.

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal polymer film, more specifically, to a liquid crystal polymer film having a specific heat of fusion and surface properties. The liquid crystal polymer film of the present invention has properties such as a low dielectric constant (Dk) and a low dielectric loss tangent (Df), and is particularly suitable for printed circuit boards in the high frequency range. Therefore, the present invention relates to a metal clad laminate and a printed circuit board manufactured using this liquid crystal polymer film. [Background technology]

[0002] In recent years, the development of mobile communication technology has been accelerating. As the fifth generation of mobile phone communication technology becomes more widespread, the commercialization of sixth generation mobile communication technology is imminent. With this, future information transmission speeds will increase by more than ten times compared to the current level, reaching 1 gigabit per second (1 Gb / s). Therefore, to ensure efficient information transmission, higher frequency bandwidths are required, and the millimeter-wave high frequency band (24 gigahertz (GHz) to 100 GHz) has been selected as the primary frequency band.

[0003] Current fourth-generation mobile communication technology mainly uses flexible copper clad laminates (FCCLs), which are made by alternately laminating polyimide (PI) film and copper foil. However, polyimide film has problems such as high moisture absorption, high dielectric constant, and high dielectric loss tangent, which cause polyimide film flexible copper clad laminates to have poor signal transmission and signal loss performance at high operating frequencies (e.g., 10 GHz). Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors' research and discovery has revealed that by controlling the heat of fusion and the ratio (Sq / Sa) of the root mean square deviation (Sq) of the surface to the arithmetic mean height (Sa) within a specific range, a liquid crystal polymer film having a low dielectric constant (Dk) and a low dielectric loss tangent (Df) can be provided. This liquid crystal polymer film is particularly suitable for printed circuit boards in the high-frequency range. Furthermore, metal clad laminates and printed circuit boards using the liquid crystal polymer film of the present invention as a dielectric layer also have good peel strength. [Means for solving the problem]

[0005] Therefore, one object of the present invention is to provide a liquid crystal polymer film having a heat of fusion of 0.50 J / g to 1.10 J / g and having a first surface and a second surface opposite to the first surface, wherein the ratio (Sq / Sa) of the root mean square height (Sq) to the arithmetic mean height (Sa) of the first surface is 1.20 to 2.30, where Sq and Sa are defined in accordance with ISO 25178-2:2012 and are expressed in micrometers.

[0006] In one embodiment of the present invention, the first surface has an Sq of 0.04 micrometers or more.

[0007] In one embodiment of the present invention, the Sq of the first surface is 0.04 micrometers or more, and the Sa of the first surface is 0.30 micrometers or less.

[0008] In one embodiment of the present invention, the ratio of Sq to Sa (Sq / Sa) of the second surface is 1.20 to 2.30, where Sq and Sa are defined in accordance with ISO 25178-2:2012 and both are expressed in micrometers.

[0009] In one embodiment of the present invention, the ratio of Sq to Sa (Sq / Sa) of the second surface is 1.20 to 2.30, and the Sq of the second surface is 0.04 micrometers or more.

[0010] In one embodiment of the present invention, the ratio of Sq to Sa (Sq / Sa) of the second surface is 1.20 to 2.30, Sq of the second surface is 0.04 micrometers or more, and Sa of the second surface is 0.30 micrometers or less.

[0011] In one embodiment of the present invention, the heat of fusion of the liquid crystal polymer film is measured under the following conditions: using a differential scanning calorimeter (DSC) under 1 atmosphere, the temperature is increased from 80°C to 400°C at a rate of 10°C per minute.

[0012] In one embodiment of the present invention, the melting point of the liquid crystal polymer film is 270°C to 330°C.

[0013] In one embodiment of the present invention, the melting point of the liquid crystal polymer film is 270° C. to 330° C., and the spectrum of the liquid crystal polymer film obtained by measurement with the differential scanning calorimeter exhibits a unimodal distribution.

[0014] Another object of the present invention is to provide a metallized laminate comprising the liquid crystal polymer film described above, which includes a first metal layer disposed on a first surface of the liquid crystal polymer film.

[0015] In one embodiment of the present invention, the metallized laminate further comprises a second metal layer disposed on the second surface of the liquid crystal polymer film.

[0016] In one embodiment of the present invention, the first metal layer and / or the second metal layer has a ten-point mean roughness (Rz) of 2.5 micrometers or less.

[0017] It is yet another object of the present invention to provide a printed circuit board manufactured from said metal clad laminate.

[0018] In order to make the above objectives, technical features and advantages of the present invention more clearly understandable, some specific embodiments are described in detail below. DETAILED DESCRIPTION OF THE INVENTION

[0019] Some specific embodiments of the present invention will be described below, but the present invention can be implemented in various forms, and the scope of protection of the present invention should not be limited to the specific embodiments described in the description.

[0020] As used herein (particularly in the claims which follow), the terms "a," "the," "the," and similar terms are understood to include the singular and plural unless the context clearly indicates otherwise.

[0021] Numerical ranges used herein (e.g., 5 to 100) are understood to include all rational numbers subsumed within that range and ranges made up of any rational number within that range. Thus, the numerical ranges used herein include all possible combinations of numerical values ​​between the minimum and maximum values ​​recited.

[0022] As used in the specification and claims, unless otherwise specified, the terms "first," "second," and similar terms are used only to distinguish between described elements or components and do not carry any special meaning or denote any order.

[0023] In this text, the terms "root mean square height (Sq)" and "arithmetic mean height (Sa)" are defined in accordance with ISO 25178-2:2012. Sq refers to the root mean square value of the height of each point on a surface within a specified area. Sa refers to the average absolute value of the difference in height of each point relative to the mean plane relative to the surface.

[0024] The advantages of the present invention compared to the existing technology are to provide a liquid crystal polymer film having a specific heat of fusion and a ratio (Sq / Sa) of root mean square height (Sq) to arithmetic mean height (Sa), and to provide a metal clad laminate and a printed circuit board using this liquid crystal polymer film. This liquid crystal polymer film has particularly low dielectric constant (Dk) and low dielectric loss tangent (Df) properties, making it particularly suitable for printed circuit boards in the high frequency range. The liquid crystal polymer film of the present invention and its related applications are described in detail below.

[0025] 1. Liquid crystal polymer film The present invention provides a liquid crystal polymer film for use in metal clad laminates and printed circuit boards. This liquid crystal polymer film is a film formed by processing and molding a liquid crystal polymer, more specifically, a film formed by processing and molding a liquid crystal polymer without undergoing an etching process. Thus, the liquid crystal polymer film of the present invention comprises a liquid crystal polymer, consists essentially of a liquid crystal polymer, or consists entirely of a liquid crystal polymer.

[0026] As used herein, liquid crystal polymer refers to a polymer that exhibits a liquid crystal state under certain conditions, including liquid crystal polyester (LCP), liquid crystal polyesteramide (LC-PEA), liquid crystal polyether (LC-PE), liquid crystal polycarbonate (LC-PC), liquid crystal polyesterimide (LC-PEI), liquid crystal polyamide (LCPA), etc. In one embodiment of the present invention, the liquid crystal polymer film of the present invention is a liquid crystal polyester film.

[0027] The liquid crystal polymer film of the present invention can have a single-layer structure or a multi-layer structure, and there is no particular limitation on its thickness. In one embodiment of the present invention, the liquid crystal polymer film of the present invention has a single-layer structure, and its thickness is 10 micrometers to 500 micrometers, more specifically 10 micrometers to 300 micrometers, even more specifically 15 micrometers to 200 micrometers, even more specifically 15 micrometers to 150 micrometers, even more specifically 20 micrometers to 150 micrometers, and even more specifically 20 micrometers to 100 micrometers. For example, the thickness of the liquid crystal polymer film of the present invention may be 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 75 micrometers, 80 micrometers, 85 micrometers, 90 micrometers, 95 micrometers, 100 micrometers, 105 micrometers, 110 micrometers, 115 micrometers, 120 micrometers, 125 micrometers, 130 micrometers, 135 micrometers, 140 micrometers, 145 micrometers, 150 micrometers, 155 micrometers Torr, 160 micrometers, 165 micrometers, 170 micrometers, 175 micrometers, 180 micrometers, 185 micrometers, 190 micrometers, 195 micrometers, 200 micrometers, 205 micrometers, 210 micrometers, 215 micrometers, 220 micrometers, 225 micrometers, 230 micrometers, 235 micrometers, 240 micrometers, 245 micrometers, 250 micrometers, 255 micrometers, 260 micrometers, 265 micrometers, 270 micrometers, 275 micrometers, 280 micrometers, 285 micrometers, 290 micrometers, 295 micrometers, 300 micrometers, 305 micrometers,310 micrometers, 315 micrometers, 320 micrometers, 325 micrometers, 330 micrometers, 335 micrometers, 340 micrometers, 345 micrometers, 350 micrometers, 355 micrometers, 360 micrometers, 365 micrometers, 370 micrometers, 375 micrometers, 380 micrometers, 385 micrometers, 390 micrometers, 395 micrometers, 400 micrometers, 405 micrometers, 410 micrometers, 415 micrometers, 420 micrometers, 425 micrometers, 430 micrometers, 435 micrometers, 440 micrometers, 445 micrometers, 450 micrometers, 455 micrometers, 460 micrometers, 465 micrometers, 470 micrometers, 475 micrometers, 480 micrometers, 485 micrometers, 490 micrometers, 495 micrometers, or 500 micrometers, or a range consisting of any two of the above numbers. ,

[0028] 1.1. Heat of fusion The liquid crystal polymer film of the present invention has a heat of fusion of 0.50 Joules / gram (J / g) to 1.10 J / g, more preferably 0.52 J / g to 1.08 J / g. For example, the heat of fusion of the liquid crystal polymer film of the present invention is 0.50 J / g, 0.51 J / g, 0.52 J / g, 0.53 J / g, 0.54 J / g, 0.55 J / g, 0.56 J / g, 0.57 J / g, 0.58 J / g, 0.59 J / g, 0.60 J / g, 0.61 J / g, 0.62 J / g, 0.63 J / g. , 0.64J / g, 0.65J / g, 0.66J / g, 0.67J / g, 0.68J / g, 0.69J / g, 0.70J / g, 0.71J / g, 0.7 2J / g, 0.73J / g, 0.74J / g, 0.75J / g, 0.76J / g, 0.77J / g, 0.78J / g, 0.79J / g, 0.80J / g , 0.81J / g, 0.82J / g, 0.83J / g, 0.84J / g, 0.85J / g, 0.86J / g, 0.87J / g, 0.88J / g, 0. 89J / g, 0.90J / g, 0.91J / g, 0.92J / g, 0.93J / g, 0.94J / g, 0.95J / g, 0.96J / g, 0.97J / g, 0.98 J / g, 0.99 J / g, 1.00 J / g, 1.01 J / g, 1.02 J / g, 1.03 J / g, 1.04 J / g, 1.05 J / g, 1.06 J / g, 1.07 J / g, 1.08 J / g, 1.09 J / g, or 1.10 J / g, or a range consisting of any two of the foregoing values.

[0029] In this paper, the heat of fusion of liquid crystal polymer films is measured using a differential scanning calorimeter (DSC) under the following conditions: heating from 80°C to 400°C at a rate of 10°C per minute under 1 atmosphere.

[0030] 1.2. Ratio of root mean square height to arithmetic mean height (Sq / Sa) The liquid crystal polymer film of the present invention has a first surface and a second surface opposite to the first surface, and the ratio of the root mean square height to the arithmetic mean height (Sq / Sa) of the first surface is 1.20 to 2.30. For example, it is 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20, 2.25, or 2.30, or a range consisting of any two of the above values. By controlling the heat of fusion and Sq / Sa value of the liquid crystal polymer film within the above specified ranges, the liquid crystal polymer film of the present invention has low Dk and low Df properties and is particularly suitable for printed circuit boards in the high-frequency range.

[0031] In one embodiment of the present invention, in addition to having this Sq / Sa value, the first surface of the liquid crystal polymer film has a root mean square height (Sq) value of 0.040 micrometers or greater, more specifically 0.045 micrometers or greater, and even more specifically 0.045 micrometers or greater and 0.325 micrometers or less.For example, the Sq value of the liquid crystal polymer film is 0.040 micrometers, 0.045 micrometers, 0.050 micrometers, 0.055 micrometers, 0.060 micrometers, 0.065 micrometers, 0.070 micrometers, 0.075 micrometers, 0.080 micrometers, 0.085 micrometers, 0.090 micrometers, 0.095 micrometers, 0.100 micrometers, 0.105 micrometers, 0.110 micrometer, 0.115 micrometer, 0.120 micrometer, 0.125 micrometer, 0.130 micrometer, 0.135 micrometer, 0.140 micrometer, 0.145 micrometer, 0.150 micrometer, 0.155 micrometer, 0.160 micrometer, 0.165 micrometer, 0.170 micrometer, 0.175 micrometer, 0.180 micrometer, 0.185 micrometers, 0.190 micrometers, 0.195 micrometers, 0.200 micrometers, 0.205 micrometers, 0.210 micrometers, 0.215 micrometers, 0.22 micrometers, 0.225 micrometers, 0.230 micrometers, 0.235 micrometers, 0.240 micrometers, 0.245 micrometers, 0.250 micrometers, 0.255 micrometers, 0.260 micrometers, 0.265 micrometers, 0.270 micrometers, 0.275 micrometers, 0.280 micrometers, 0.285 micrometers, 0.290 micrometers, 0.295 micrometers, 0.300 micrometers, 0.305 micrometers, 0.310 micrometers, 0.315 micrometers, 0.320 micrometers, or 0.325 micrometers, or a range consisting of any two of the foregoing numbers.

[0032] In one embodiment of the present invention, in addition to having this Sq / Sa value and Sq value, the first surface of the liquid crystal polymer film has an arithmetic mean height (Sa) of 0.300 micrometers or less, more specifically 0.025 micrometers or more and 0.300 micrometers or less, and even more specifically 0.025 micrometers or more and 0.250 micrometers or less.For example, the Sa value of the first surface of the liquid crystal polymer film is 0.025 micrometers, 0.030 micrometers, 0.035 micrometers, 0.040 micrometers, 0.045 micrometers, 0.050 micrometers, 0.055 micrometers, 0.060 micrometers, 0.065 micrometers, 0.070 micrometers, 0.075 micrometers, 0.080 micrometers, 0.085 micrometers, 0.090 micrometers, 0.095 micrometers, 0.100 micrometers, 0.105 micrometers, 0.110 micrometers, 0.115 micrometers, 0.120 micrometers, 0.125 micrometers, 0.130 micrometers, 0.135 micrometers, 0.140 micrometers, 0.145 micrometers, 0.150 micrometers, 0.155 micrometers, 0.160 micrometers, 0.170 micrometers, 0.175 micrometers, 0.180 micrometers, 0.185 micrometers, 0.190 micrometers, 0.195 micrometers, 0.200 micrometers, 0.210 micrometers, 0.220 micrometers, 0.230 micrometers, 0.240 micrometers, 0.250 micrometers, 0.260 micrometers, 0.270 micrometers, 0.280 micrometers, 0.290 micrometers, 0.300 micrometers, 0.310 micrometers, 0.320 micrometers, 0.330 micrometers, 0.340 micrometers, 0.3 65 micrometers, 0.170 micrometers, 0.175 micrometers, 0.180 micrometers, 0.185 micrometers, 0.190 micrometers, 0.195 micrometers, 0.200 micrometers, 0.205 micrometers, 0.210 micrometers, 0.215 micrometers, 0.220 micrometers, 0.225 micrometers, 0.230 micrometers, 0.235 micrometers, 0.240 micrometers, 0.245 micrometers, 0.250 micrometers, 0.255 micrometers, 0.260 micrometers, 0.265 micrometers, 0.270 micrometers, 0.275 micrometers, 0.280 micrometers, 0.285 micrometers, 0.290 micrometers, 0.295 micrometers, or 0.300 micrometers, or a range consisting of any two of the foregoing numbers.

[0033] In one embodiment of the present invention, the first surface and the second surface each independently have the above-mentioned Sq / Sa value, more preferably each independently have the above-mentioned Sq / Sa value and Sq value, and even more preferably each independently have the above-mentioned Sq / Sa value, Sq value and Sa value.

[0034] 1.3. Other Properties In one embodiment of the present invention, the melting point of the liquid crystal polymer film is 270°C to 340°C, more specifically 270°C to 330°C, even more specifically 275°C to 330°C, and even more specifically 275°C to 325°C. For example, the melting point of the liquid crystal polymer film is 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, or 340°C, or a range consisting of any two of the above values. The melting point of the liquid crystal polymer film is measured using a differential scanning calorimeter (DSC) at 1 atmosphere pressure, increasing the temperature at a rate of 10°C per minute, and the resulting spectrum preferably exhibits a unimodal distribution.

[0035] In one embodiment of the present invention, the liquid crystal polymer film has a ratio (H(S) / H(I)) of the surface layer hardness (H(S)) at an indentation depth of 20 nanometers to the inner layer hardness (H(I)) at an indentation depth of 200 nanometers, as measured by nanoindentation, of 1.0 to 1.5.

[0036] 1.4. Liquid Crystal Polymer Film Production The method for producing the liquid crystal polymer film of the present invention is not particularly limited. For example, a liquid crystal polymer is placed in an extruder and heated, and the heated and extruded liquid crystal polymer is wrapped with a film material using a cast roll and a winding mechanism to form a three-layer structure of "film material-liquid crystal polymer film-film material." This three-layer structure is then cooled, and the film material and the liquid crystal polymer film are separated after cooling to obtain a liquid crystal polymer film.

[0037] Alternatively, the liquid crystal polymer film of the present invention can be produced using a blow molding method. In this method, a molten liquid crystal polymer is extruded through an annular die, and stress is applied to the extruded film in the machine axis direction (also known as the machine processing direction, MD) and / or in a direction perpendicular to the machine axis direction (the transverse direction or TD), thereby obtaining a liquid crystal polymer film having controlled molecular orientation and dielectric properties in the MD and TD directions. If necessary, stretching treatment can be performed in the MD and TD directions to promote control of the molecular orientation. The stretching ratio is usually, but is not limited to, 1 to 10 times.

[0038] During the manufacturing process of the liquid crystal polymer film, additives such as lubricants, antioxidants, electrical insulating agents, and fillers can be added. Examples of additives include, but are not limited to, polycarbonate, polyamide, polyphenylene sulfide, and polyether ether ketone. Examples of film materials include, but are not limited to, inorganic film materials and high-temperature resistant organic film materials. For example, inorganic film materials such as copper foil and aluminum foil, and high-temperature resistant organic film materials such as polyimide film, polytetrafluoroethylene film, and polyethersulfone film.

[0039] The heat of fusion and Sq / Sa value of the liquid crystal polymer film can be adjusted, for example, by controlling the extruder temperature, casting roll temperature and / or casting roll rotation speed. Specifically, the heat of fusion, Sq value and Sa value are interdependent with the extruder temperature, casting roll temperature and casting roll rotation speed, so by adjusting the extruder temperature, casting roll temperature and casting roll rotation speed, the heat of fusion, Sq value and Sa value of the liquid crystal polymer film can be adjusted, and the heat of fusion and Sq / Sa value can be adjusted within the range specified in the present invention.

[0040] Liquid crystal polymers can be commercially available or chemically synthesized. Chemical synthesis can be carried out using, for example, aromatic or aliphatic hydroxy compounds, aromatic or aliphatic dicarboxylic acids, aromatic hydroxycarboxylic acids, and aromatic amines. Examples of aromatic or aliphatic hydroxy compounds include, but are not limited to, hydroquinone, resorcinol, 2,6-naphthalenediol, ethanediol, 1,4-butanediol, and 1,6-hexanediol. Examples of aromatic or aliphatic dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2-chloroterephthalic acid, and adipic acid. Examples of aromatic hydroxycarboxylic acids include, but are not limited to, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthalene carboxylic acid, and 4'-hydroxy-4-biphenylcarboxylic acid. Examples of aromatic amine compounds include, but are not limited to, p-phenylenediamine, 4,4'-diaminobiphenyl, naphthalene-2,6-diamine, 4-aminophenol, 4-amino-3-methylphenol, and 4-aminobenzoic acid.In one embodiment of the present invention, the liquid crystal polymer comprises structural units derived from 6-hydroxy-2-naphthalenecarboxylic acid and 4-hydroxybenzoic acid, and the liquid crystal polymer can be produced by a condensation polymerization reaction between 6-hydroxy-2-naphthalenecarboxylic acid and 4-hydroxybenzoic acid, and the condensation polymerization reaction can be carried out in the presence of a reaction promoter such as acetic anhydride.

[0041] If necessary, the liquid crystal polymer film of the present invention may be subjected to a post-treatment. Examples of post-treatments include, but are not limited to, plasma treatment, ultraviolet irradiation, heat treatment, or physical polishing. Plasma treatments include direct plasma treatment and long-distance plasma treatment. Direct plasma treatment involves placing the liquid crystal polymer film in a discharge space and directly subjecting it to plasma treatment, while long-distance plasma treatment involves spraying activated materials generated in the discharge space onto the surface of the liquid crystal polymer film. UV irradiation treatment can be performed by irradiating the liquid crystal polymer film with ultraviolet light having a dominant wavelength of 275 nanometers or more, preferably 300 nanometers or more, in an inert gas atmosphere such as vacuum, air, or nitrogen. Here, "dominant wavelength" refers to the wavelength corresponding to the maximum energy in the wavelength energy distribution of the ultraviolet light used. Examples of physical polishing treatments include, but are not limited to, brush polishing, sandblasting polishing, sander belt polishing, and drum polishing. In one embodiment of the present invention, the liquid crystal polymer film is subjected to plasma treatment, but the present invention is not limited thereto. The plasma treatment is preferably direct plasma treatment.

[0042] 2. Metal coated laminate The present invention provides a metal clad laminate manufactured from the above-described liquid crystal polymer film by laminating the above-described liquid crystal polymer film and a metal layer. The liquid crystal polymer film functions as a dielectric layer, and the metal layer functions as a conductive layer. Specifically, the present invention provides a metal clad laminate including the above-described liquid crystal polymer film and a first metal layer disposed on a first surface of the liquid crystal polymer film. The material of the first metal layer may be any material capable of providing a conductive function, including, but not limited to, copper, gold, silver, nickel, aluminum, stainless steel, or alloys or composites thereof. In one embodiment of the present invention, the first metal layer is copper foil.

[0043] An intermediate layer may or may not be present between the liquid crystal polymer film and the first metal layer. For example, an adhesive layer may be used to promote adhesion between the liquid crystal polymer film and the first metal layer. An example of an intermediate layer is an adhesive layer. The first metal layer itself may undergo surface treatments, such as anti-corrosion treatments and organic coupling agent treatments, resulting in the formation of a corresponding layer on the surface of the first metal layer. Therefore, the intermediate layer may be an anti-corrosion layer or an organic coupling agent layer. Anti-corrosion layer materials include, but are not limited to, nickel, zinc, chromium, cobalt, molybdenum, manganese, iron, tin, vanadium, tungsten, and titanium, with nickel, zinc, and chromium being more preferred. The anti-corrosion layer materials may be used alone or in combination. The organic coupling agent layer materials include, but are not limited to, silane compounds, porphyrin compounds, benzotriazole compounds, and trisulfonic acid compounds, with silane compounds being more preferred. The organic coupling agent layer materials may be used alone or in combination.

[0044] In one embodiment of the present invention, the metal clad laminate further includes a second metal layer disposed on the second surface of the liquid crystal polymer film. An intermediate layer may or may not be present between the liquid crystal polymer film and the second metal layer. Examples of intermediate layers include, but are not limited to, the adhesive layer, anti-corrosion layer, and organic coupling agent layer described above. The material of the second metal layer may be any material capable of providing electrical conductivity, including, but not limited to, the materials described above for the first metal layer.

[0045] The thickness of the first metal layer and the second metal layer is not particularly limited and can be adjusted appropriately according to actual usage needs. For example, the thickness of the first metal layer and the second metal layer is independently 1 micrometer to 200 micrometers, more specifically, independently 1 micrometer to 40 micrometers, and even more specifically, independently 1 micrometer to 20 micrometers, but the present invention is not limited thereto.

[0046] The first metal layer and the second metal layer may be subjected to a surface treatment to achieve desired surface properties, including, but not limited to, a roughening treatment, an acid-alkali treatment, a heat treatment, a degreasing treatment, an ultraviolet irradiation treatment, a corona discharge treatment, a plasma treatment, an organic coupling agent treatment, and a rust prevention treatment.

[0047] In one embodiment of the present invention, the ten-point arithmetic mean height (Rz) of the first metal layer and the second metal layer is each independently 2.5 micrometers or less, more specifically, 0.5 micrometers to 2.5 micrometers, as defined in JIS B 0601: 1994. For example, the Rz of the first metal layer and the second metal layer is each independently 0.5 micrometer, 0.6 micrometer, 0.7 micrometer, 0.8 micrometer, 0.9 micrometer, 1.0 micrometer, 1.1 micrometer, 1.2 micrometer, 1.3 micrometer, 1.35 micrometer, 1.4 micrometer, 1.45 micrometer, 1.5 micrometer, 1.6 micrometer, 1.7 micrometer, 1.8 micrometer, 1.9 micrometer, 2.0 micrometer, 2.1 micrometer, 2.2 micrometer, 2.3 micrometer, 2.4 micrometer, or 2.5 micrometer, or within a range formed by any two of the above values.

[0048] 3. Printed circuit board The present invention further provides a printed circuit board manufactured by patterning the first metal layer and / or the second metal layer of the metal-coated laminate of the present invention. The method for patterning the first metal layer and / or the second metal layer is not particularly limited, and examples thereof include, but are not limited to, a photoetching method.

[0049] 4. Working Example 4.1. Description of measurement method The present invention will be further illustrated and explained below using specific embodiments, in which the measuring instruments and methods used are as follows:

[0050] [Heat of fusion and melting point measurement] The liquid crystal polymer film is dried to remove moisture. 3 to 20 milligrams (more preferably 3 to 10 milligrams, and even more preferably 5 to 10 milligrams) of the dried liquid crystal polymer film is taken, and the heat of fusion and melting point of the liquid crystal polymer film are measured using a differential scanning calorimeter (model number: Q200, purchased from TA Instruments) by heating from 80°C to 400°C at a rate of 10°C per minute under 1 atmosphere.

[0051] [Measurement of root mean square height (Sq) and arithmetic mean height (Sa)] Using a laser scanning confocal microscope (model number: LEXT OLS5000-SAF, purchased from Olympus Corporation, objective lens: MPLAPON-50xLEXT), the surface features of the liquid crystal polymer film were observed and images were acquired under conditions of 24±3°C temperature, 63±3% relative humidity, a 405 nm light source, 50x objective lens magnification, and 1.0x optical zoom. Next, the mode was set to auto tilt removal, and the resolution was set to 1024x1024 pixels. The images were then analyzed to obtain the root mean square height (Sq) and arithmetic mean height (Sa) of the surface of the liquid crystal polymer film, and the Sq / Sa value was calculated.

[0052] [Dielectric property measurement] Using a microwave dielectric analyzer purchased from AET Japan, the dielectric constant (Dk) and dielectric loss tangent (Df) of the liquid crystal polymer film are measured and calculated at an operating frequency of 10 GHz and a temperature of 25°C according to the standard method defined in IPC-TM-650 2.5.5.13.

[0053] Before the measurement, the device is calibrated under 40% relative humidity using a calibration kit. The liquid crystal polymer film is cut into a thin strip at least 9 cm long and 7 cm wide. The cut liquid crystal polymer film is then placed into a resonant cavity. The dielectric constant and dielectric loss tangent of the liquid crystal polymer film are then measured within 1 minute using a vector network analyzer (VNA).

[0054] [Peel strength analysis] A 50-micrometer-thick liquid crystal polymer film was placed between two sheets of 12-micrometer-thick commercially available copper foil (model number: CF-T49A-HD2, Rz is 1.2 micrometers, purchased from Fukuda Metal Foil and Powder Co., Ltd.), and the temperature was first 180°C and the pressure was 5 kilograms per square centimeter (kg / cm 2 ) pressure for 60 seconds, then heated to 300°C or 340°C and 20 kg / cm 2 The copper foil laminate was obtained by compressing the laminate at a pressure of 100°C for 25 minutes and then cooling to room temperature. In consideration of the melting point, Examples E1 to E6 and Comparative Examples CE1 and CE4, which used the liquid crystal polymer resin of Production Example 1, used a compression temperature of 300°C, while Examples E7 to E12 and Comparative Examples CE2, CE3, and CE5, which used the liquid crystal polymer resin of Production Example 2, used a compression temperature of 340°C.

[0055] The copper foil laminate was processed into etched specimens measuring 228.6 mm in length and 3.2 mm in width according to the standard method defined in IPC-TM-650 No. 2.4.9. Each specimen was then stabilized for 24 hours at a temperature of 23±2°C and a relative humidity of 50±5%. Each specimen was then attached to the clamp of a test stand (model number: HT-9102, purchased from Hung Ta Instrument Co., Ltd.) with double-sided tape. The specimen was then peeled from the clamp at a rate of 50.8 mm per minute, and the peel strength was continuously recorded during the peeling process. The peel strength was controlled within a range of 15% to 85% of the test stand's capacity. The peel length must exceed at least 57.2 mm, ignoring the first 6.4 mm of peel strength. The units of peel strength are kilogram force per centimeter (kgf / cm).

[0056] [Nanoindentation / Hardness Analysis] Nanoindentation / hardness tests were performed on liquid crystal polymer films at a temperature of 23°C and a relative humidity of 40% using a nanoindentation machine (model number: Triboscope, purchased from HYISTRON) equipped with a diamond indenter (Berkovich type) and a measuring needle with a tip diameter of 150 nanometers. The hardness measured when the tip of the measuring needle is inserted 20 nanometers deep from the top surface of the film is defined as H(S) (i.e., the hardness of the surface layer). The hardness measured when the tip of the measuring needle is inserted 200 nanometers deep from the top surface of the film is defined as H(I) (i.e., the hardness of the inner layer). Measurements were taken at 10 random points on one surface of the liquid crystal polymer film, and the average of the 10 measurement results was used as the experimental result.

[0057] 4.2. Liquid Crystal Polymer Resin Production [Manufacturing Example 1] 540 grams of 6-hydroxy-2-naphthalenecarboxylic acid, 1071 grams of 4-hydroxybenzoic acid, 1085 grams of acetic anhydride, and 1.3 grams of sodium phosphite were added to a 3-liter autoclave and the acetylation reaction was carried out under nitrogen atmosphere at atmospheric pressure at 160°C for 2 hours. The autoclave temperature was then increased to 320°C at a rate of 30°C per hour. At 320°C, the pressure in the autoclave was gradually reduced from 760 torr to below 3 torr, and the temperature was then gradually increased from 320°C to 340°C. The mixture was then subjected to a series of processes, including increasing the stirring power, pressurization, discharge, strand drawing, and pelletization, resulting in a liquid crystal polymer resin with a melting point of 280°C and a viscosity of 40 Pascal-seconds (Pa.s) at 300°C.

[0058] [Manufacturing Example 2] 400 grams of 6-hydroxy-2-naphthalenecarboxylic acid, 1175 grams of 4-hydroxybenzoic acid, 1085 grams of acetic anhydride, and 1.3 grams of sodium phosphite were added to a 3-liter autoclave and the acetylation reaction was carried out under nitrogen atmosphere at atmospheric pressure and 160°C for 2 hours. The autoclave temperature was then increased to 320°C at a rate of 30°C per hour. At 320°C, the pressure in the autoclave was slowly reduced from 760 Torr to 3 Torr or less, and the temperature was then slowly increased from 320°C to 340°C. The mixture was then subjected to increased stirring, pressurization, discharge, strand drawing, pelletization, and other steps to obtain a liquid crystal polymer resin with a melting point of 320°C and a viscosity of 40 Pascal·s at 320°C.

[0059] 4.3. Liquid Crystal Polymer Film Production [Example E1] The liquid crystal polymer resin of Production Example 1 was placed into an extruder (model: ZSE27, supplier: Leistritz) with a screw diameter of 27 mm and heated to 280°C. The liquid crystal polymer resin was then extruded through a 500 mm wide T-die at a rate of 8.5 kilograms per hour. Next, a polyimide film (supplied by: SKC) was fed through a winding mechanism onto two casting rolls with a diameter of 35 to 45 centimeters and a temperature of 250°C. A three-layer structure was formed with the liquid crystal polymer resin extruded from the T-die at a casting roll rotation speed of 150 rpm. The film was then cooled to room temperature on a cooling roll and wound up. The three-layer structure was separated at a speed of 0.5 to 20 meters per minute with a force of 50 to 1000 grams per centimeter, yielding a 50 micrometer thick liquid crystal polymer film of Example E1. Nanoindentation / hardness analysis of the liquid crystal polymer film of Example E1 showed an H(S) / H(I) value of 1.372. The liquid crystal polymer film of Example E1 was analyzed by a differential scanning calorimeter, and the spectrum obtained showed a single-modal distribution.

[0060] [Example E2] A liquid crystal polymer film of Example E2 having a thickness of 50 micrometers was prepared in the same manner as in Example E1, except that the temperature of the casting roll was adjusted to 260°C. Nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E2 showed that the H(S) / H(I) value was 1.277. The liquid crystal polymer film of Example E2 was analyzed by differential scanning calorimetry, and the spectrum obtained showed a unimodal distribution.

[0061] [Example E3] A 50 micrometer thick liquid crystal polymer film of Example E3 was produced in the same manner as in Example E1, except that the extruder temperature was adjusted to 290°C, the casting drum temperature to 270°C, and the casting drum rotation speed to 120 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E3 showed an H(S) / H(I) value of 1.329. The liquid crystal polymer film of Example E3 was analyzed by differential scanning calorimetry, and the spectrum obtained showed a unimodal distribution.

[0062] [Example E4] A 50 micrometer thick liquid crystal polymer film of Example E4 was produced in the same manner as in Example E1, except that the extruder temperature was adjusted to 290°C, the casting roll temperature to 280°C, and the casting roll rotation speed to 120 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E4 showed an H(S) / H(I) value of 1.247. The liquid crystal polymer film of Example E4 was analyzed by differential scanning calorimetry, and the spectrum obtained showed a unimodal distribution.

[0063] [Example E5] A 50 micrometer thick liquid crystal polymer film of Example E5 was produced in the same manner as in Example E1, except that the extruder temperature was adjusted to 300°C, the casting roll temperature to 290°C, and the casting roll rotation speed to 100 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E5 showed an H(S) / H(I) value of 1.409. The liquid crystal polymer film of Example E5 was analyzed by differential scanning calorimetry, and the spectrum obtained showed a unimodal distribution.

[0064] [Example E6] A 50 micrometer thick liquid crystal polymer film of Example E6 was produced in the same manner as in Example E1, except that the extruder temperature was 300°C, the casting roll temperature was 300°C, and the casting roll rotation speed was 100 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E6 showed an H(S) / H(I) value of 1.397. The liquid crystal polymer film of Example E6 was analyzed by differential scanning calorimetry, and the spectrum obtained showed a unimodal distribution.

[0065] [Example E7] The liquid crystal polymer resin of Production Example 2 was placed into an extruder (model: ZSE27, supplier: Leistritz) with a screw diameter of 27 mm and heated to 320°C. The liquid crystal polymer resin was then extruded through a 500 mm wide T-die at a rate of 8.5 kilograms per hour. Next, a polyimide film (supplied by: SKC) was fed through a winding mechanism onto two casting rolls with a diameter of 35 to 45 centimeters and a temperature of 280°C. A three-layer structure was formed with the liquid crystal polymer resin extruded from the T-die at a casting roll rotation speed of 200 rpm. The film was then cooled to room temperature on a cooling roll and wound up. The three-layer structure was separated at a speed of 0.5 to 20 meters per minute with a force of 50 to 1000 grams per centimeter, yielding a 50 micrometer thick liquid crystal polymer film of Example E7. Nanoindentation / hardness analysis of the liquid crystal polymer film of Example E7 showed an H(S) / H(I) value of 1.143. The liquid crystal polymer of Example E7 was analyzed by a differential scanning calorimeter, and the spectrum obtained showed a single-peak distribution.

[0066] [Example E8] A liquid crystal polymer film of Example E8 having a thickness of 50 micrometers was prepared in the same manner as in Example E7, except that the temperature of the casting roll was adjusted to 290°C. The nanoindentation / hardness analysis result of the liquid crystal polymer film of Example E8 showed that the H(S) / H(I) value was 1.069. The liquid crystal polymer film of Example E8 was analyzed by a differential scanning calorimeter, and the spectrum obtained showed a unimodal distribution.

[0067] [Example E9] A 50 micrometer thick liquid crystal polymer film of Example E9 was produced in the same manner as in Example E7, except that the extruder temperature was adjusted to 330°C, the casting roll temperature to 300°C, and the casting roll rotation speed to 150 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E9 showed an H(S) / H(I) value of 1.208. The liquid crystal polymer film of Example E9 was analyzed by differential scanning calorimetry, and the spectrum obtained showed a unimodal distribution.

[0068] [Example E10] A 50 micrometer thick liquid crystal polymer film of Example E10 was produced in the same manner as in Example E7, except that the extruder temperature was adjusted to 330°C, the casting roll temperature to 310°C, and the casting roll rotation speed to 150 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E10 showed that the H(S) / H(I) value was 1.022. The liquid crystal polymer film of Example E10 was analyzed using a differential scanning calorimeter, and the spectrum obtained showed a unimodal distribution.

[0069] [Example E11] A liquid crystal polymer film of Example E11 having a thickness of 50 micrometers was produced in the same manner as in Example E7, except that the extruder temperature was adjusted to 340°C, the casting roll temperature to 320°C, and the casting roll rotation speed to 100 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E11 showed that the H(S) / H(I) value was 1.333. The liquid crystal polymer film of Example E11 was analyzed using a differential scanning calorimeter, and the spectrum obtained showed a unimodal distribution.

[0070] [Example E12] A 50 micrometer thick liquid crystal polymer film of Example E12 was produced in the same manner as in Example E7, except that the extruder temperature was 340°C, the casting roll temperature was 330°C, and the casting roll rotation speed was 100 rpm. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Example E12 showed an H(S) / H(I) value of 1.184. The liquid crystal polymer film of Example E12 was analyzed by differential scanning calorimetry, and the spectrum showed a unimodal distribution.

[0071] [Comparative example CE1] A 50 micrometer thick liquid crystal polymer film of Comparative Example CE1 was produced in the same manner as in Example E1, except that the temperature of the casting roll was adjusted to 240°C and the rotation speed of the casting roll to 120 rpm. Nanoindentation / hardness analysis of the liquid crystal polymer film of Comparative Example CE1 showed an H(S) / H(I) value of 1.438. The liquid crystal polymer film of Comparative Example CE1 showed a unimodal distribution when analyzed by differential scanning calorimetry.

[0072] [Comparative Example CE2] A 50 micrometer thick liquid crystal polymer film of Comparative Example CE2 was produced in the same manner as in Example E7, except that the temperature of the casting roll was adjusted to 260°C and the rotation speed of the casting roll to 150 rpm. Nanoindentation / hardness analysis of the liquid crystal polymer film of Comparative Example CE2 showed an H(S) / H(I) value of 1.236. The liquid crystal polymer film of Comparative Example CE2 was analyzed using a differential scanning calorimeter, and the resulting spectrum showed a unimodal distribution.

[0073] [Comparative Example CE3] A 50 micrometer thick liquid crystal polymer film of Comparative Example CE3 was produced in the same manner as in Example E7, except that the extruder temperature was adjusted to 340°C and the casting roll temperature was adjusted to 340°C. Nanoindentation / hardness analysis results for the liquid crystal polymer film of Comparative Example CE3 showed an H(S) / H(I) value of 0.970. The liquid crystal polymer film of Comparative Example CE3 was analyzed using a differential scanning calorimeter, and the resulting spectrum showed a unimodal distribution.

[0074] [Comparative Example CE4] A 50 micrometer thick liquid crystal polymer film of Comparative Example CE4 was produced using the same method as in Example E1, except that the extruder temperature was adjusted to 290°C and the cast roll temperature was adjusted to 290°C. Nanoindentation / hardness analysis results for the liquid crystal polymer film of Comparative Example CE4 showed an H(S) / H(I) value of 1.056. The liquid crystal polymer film of Comparative Example CE4 was analyzed using a differential scanning calorimeter, and the resulting spectrum showed a unimodal distribution.

[0075] [Comparative Example CE5] A liquid crystal polymer film of Comparative Example CE5 having a thickness of 50 micrometers was produced in the same manner as in Example E7, except that the extruder temperature was adjusted to 330°C and the casting roll temperature to 320°C. The nanoindentation / hardness analysis results of the liquid crystal polymer film of Comparative Example CE5 showed an H(S) / H(I) value of 1.167. The liquid crystal polymer film of Comparative Example CE5 was analyzed using a differential scanning calorimeter, and the spectrum obtained showed a unimodal distribution.

[0076] 4.4. Liquid crystal polymer film property analysis According to the above-mentioned methods, various properties of the liquid crystal polymer films of Examples E1 to E12 and Comparative Examples CE1 to CE5 are tested, including heat of fusion, root mean square height, arithmetic mean height, root mean square height / arithmetic mean height value, dielectric properties, peel strength, and melting point, and the results are recorded in Table 1. Table 1: Properties of liquid crystal polymer films

[0077] [Table 1]

[0078] As shown in Table 1, the liquid crystal polymer films of the present invention (Examples E1 to E12) not only exhibit excellent dielectric properties by controlling the heat of fusion and Sq / Sa value within the specified ranges, but also provide laminates with excellent peel strength even after being laminated to copper foil. The liquid crystal polymer films of the present invention are particularly suitable for manufacturing printed circuit boards for high-frequency applications, and can maintain good information transmission and reduce signal loss. In contrast, Comparative Examples CE1 to CE5 show that the above effects cannot be achieved if either the heat of fusion or Sq / Sa value of the liquid crystal polymer film falls outside the specified ranges of the present invention.

[0079] The above examples are intended to exemplify the principles and effects of the present invention and clarify the technical features of the present invention, but are not intended to limit the scope of protection of the present invention. Modifications or arrangements that can be easily made by those skilled in the art without violating the technical principles of the present invention are included within the scope of the claimed invention. Therefore, the scope of protection of the present invention is defined in the appended claims.

[0080] [Note] [Appendix 1] A liquid crystal polymer film having a heat of fusion of 0.50 J / g to 1.10 J / g, comprising a first surface and a second surface opposite to the first surface, wherein the ratio (Sq / Sa) of root mean square deviation (Sq) to arithmetic mean height (Sa) of the first surface is 1.20 to 2.30, Sq and Sa are defined in accordance with ISO 25178-2:2012, and both are expressed in micrometers.

[0081] [Appendix 2] 2. The liquid crystal polymer film of claim 1, wherein the Sq of the first surface is 0.04 micrometers or more.

[0082] [Appendix 3] 3. The liquid crystal polymer film of claim 2, wherein the Sa of the first surface is 0.30 micrometers or less.

[0083] [Appendix 4] 2. The liquid crystal polymer film of claim 1, wherein the ratio of Sq to Sa (Sq / Sa) of the second surface is 1.20 to 2.30, where Sq and Sa are defined in accordance with ISO 25178-2:2012 and are expressed in micrometers.

[0084] [Appendix 5] 5. The liquid crystal polymer film of claim 4, wherein the second surface has an Sq of 0.04 micrometers or more.

[0085] [Appendix 6] 6. The liquid crystal polymer film of claim 5, wherein Sa of the second surface is 0.30 micrometers or less.

[0086] [Appendix 7] The heat of fusion is measured under the following conditions: the liquid crystal polymer film described in any one of Appendices 1 to 6 is heated from 80°C to 400°C at a rate of 10°C per minute under 1 atmosphere using a differential scanning calorimeter (DSC).

[0087] [Appendix 8] 7. The liquid crystal polymer film according to any one of claims 1 to 6, wherein the melting point is 270°C to 330°C.

[0088] [Appendix 9] 9. The liquid crystal polymer film according to claim 8, wherein the spectrum obtained by measurement with the differential scanning calorimeter is a unimodal distribution.

[0089] [Appendix 10] A metal-coated laminate comprising the liquid crystal polymer film according to any one of claims 1 to 9 and a first metal layer disposed on a first surface of the liquid crystal polymer film.

[0090] [Appendix 11] 11. The metal-coated laminate of claim 10, further comprising a second metal layer disposed on a second surface of the liquid crystal polymer film.

[0091] [Appendix 12] 12. The metal-coated laminate according to claim 10 or 11, wherein the ten-point mean roughness (Rz) of the first metal layer and / or the second metal layer is 2.5 micrometers or less.

[0092] [Appendix 13] A printed circuit board manufactured from the metal clad laminate according to any one of appendices 10 to 12.

Claims

1. 1. A liquid crystal polymer film having a heat of fusion of 0.50 J / g to 1.10 J / g, the liquid crystal polymer film comprising a first surface and a second surface opposite to the first surface, wherein the ratio (Sq / Sa) of the root mean square deviation (Sq) to the arithmetic mean height (Sa) of the first surface is 1.20 to 2.30, Sq and Sa are defined in accordance with ISO 25178-2:2012, and both are expressed in micrometers.

2. The liquid crystal polymer film according to claim 1 , wherein the Sq of the first surface is 0.04 micrometers or more.

3. The liquid crystal polymer film of claim 2 , wherein Sa of the first surface is 0.30 micrometers or less.

4. The liquid crystal polymer film of claim 1, wherein the ratio of Sq to Sa (Sq / Sa) of the second surface is 1.20 to 2.30, and Sq and Sa are defined in accordance with ISO 25178-2:2012 and are expressed in micrometers.

5. The liquid crystal polymer film according to claim 4 , wherein the Sq of the second surface is 0.04 micrometers or more.

6. The liquid crystal polymer film according to claim 5 , wherein Sa of the second surface is 0.30 micrometers or less.

7. The heat of fusion is measured under the following conditions: the temperature is increased from 80°C to 400°C at a rate of 10°C per minute under 1 atmosphere using a differential scanning calorimeter (DSC). The liquid crystal polymer film according to any one of claims 1 to 6.

8. A liquid crystal polymer film described in any one of claims 1 to 6, having a melting point of 270°C to 330°C.

9. A liquid crystal polymer film as described in claim 8, wherein the spectrum obtained by measurement with a differential scanning calorimeter is a unimodal distribution.

10. A metal clad laminate comprising the liquid crystal polymer film according to any one of claims 1 to 6 and a first metal layer disposed on a first surface of the liquid crystal polymer film.

11. 11. The metal clad laminate of claim 10, further comprising a second metal layer disposed on a second surface of the liquid crystal polymer film.

12. The metal clad laminate according to claim 10, wherein the first metal layer and / or the second metal layer has a ten-point mean roughness (Rz) of 2.5 micrometers or less.

13. A printed circuit board manufactured from the metal clad laminate of claim 10.

Images