Thermoplastic liquid crystal polymer film, laminate, method for producing same, and molded body

Abstract

The present invention provides a thermoplastic liquid crystal polymer film that achieves both suppression of resin flow and the capability of filling a circuit pattern when multilayering high-density circuit boards and fine circuit boards. The thermoplastic liquid crystal polymer film is composed of a thermoplastic polymer capable of forming an optically anisotropic molten phase. When the apparent melting point of the thermoplastic liquid crystal polymer film is represented by Tm (℃), a rubber-like flat region is present in the temperature range of 240℃ or higher and Tm℃ or lower in the profile of a storage elastic modulus obtained by dynamic viscoelasticity measurement, and the storage elastic modulus E'280 at 280°C is less than 60 MPa.

Description

Thermoplastic liquid crystal polymer films, laminates, methods for manufacturing the same, and molded articles Related applications

[0001] This application claims priority to Japanese Patent Application No. 2024-221038, filed in Japan on 17 December 2024, which is incorporated herein by reference as forming part of this application.

[0002] The present invention relates to a thermoplastic liquid crystal polymer film containing a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), a laminate comprising at least one layer of a thermoplastic liquid crystal polymer film, and a molded article containing a thermoplastic liquid crystal polymer film.

[0003] In recent years, the demand for miniaturization and weight reduction of equipment in the electronics, electrical, and telecommunications industries has increased the need for higher density printed circuit boards. Accordingly, various innovations are being pursued, such as multilayering of circuit boards, narrowing of wiring pitches, and miniaturization of via holes. For example, high-density circuits are manufactured by multilayering metal-clad laminates, which consist of non-metallic and metal layers, with the non-metallic layer in between. Conventionally, printed circuit boards and circuits have been manufactured by mainly using thermosetting resins such as phenolic resin and epoxy resin as the non-metallic layer, laminating them with metal layers such as copper foil. However, it is known that thermosetting resins require time for proper lamination to occur through heating reactions.

[0004] In response to this, simultaneous lamination of multiple sheets and simultaneous multi-stage manufacturing using equipment are commonly employed to improve productivity. Under these circumstances, thermoplastic liquid crystal polymer materials are expected to improve productivity by taking advantage of their thermoplastic properties, and in terms of physical properties, they are attracting considerable attention, particularly in high-frequency transmission applications, due to their extremely low water absorption rate and dielectric loss compared to other materials.

[0005] Thermoplastic liquid crystal polymer materials can be multilayered by thermocompression bonding due to their thermoplastic properties, but heat resistance is also required during multilayering. In other words, even when the non-metallic layer used in multilayering is moderately softened and plasticized and the laminate is manufactured under conditions that allow it to adhere firmly to the metal or non-metallic layer of the laminate, if the non-metallic layer of the laminate has high heat resistance, a wide process window (optimal range of manufacturing conditions) and stable products can be manufactured.

[0006] For example, Patent Document 1 (International Publication No. 2020 / 218140) proposes a thermoplastic liquid crystal polymer film in which a rubbery flat region exists and the storage modulus E' in the rubbery flat region is within a specific range, regarding the temperature dependence of the storage modulus determined by dynamic viscoelasticity measurement. It is described that the flow of the resin can be suppressed when multilayering is performed by thermocompression bonding, and that the process window is wide.

[0007] International Publication No. 2020 / 218140

[0008] However, in recent years, circuits have become more densely and miniaturized. When multilayering high-density circuit boards and miniature circuit boards, it is necessary not only to suppress the flow of resin but also to further improve the resin's ability to fill the circuit patterns, leaving room for further improvement.

[0009] The present invention aims to provide a thermoplastic liquid crystal polymer film and a method for manufacturing the same, which can suppress resin flow when multilayering high-density circuit boards and fine circuit boards, and which has high resin filling ability between circuit patterns. The invention also aims to provide a laminate comprising at least one layer of the thermoplastic liquid crystal polymer film, a method for manufacturing the same, and a molded article containing the thermoplastic liquid crystal polymer film.

[0010] As a result of diligent research to achieve the above objective, the inventors of the present invention have surprisingly found that, regarding the temperature dependence of the storage modulus obtained by dynamic viscoelasticity measurement, a rubbery flat region exists in the high-temperature range, and the storage modulus E' at 280°C is... 280We discovered that thermoplastic liquid crystal polymer films with a specific range can suppress resin flow during the manufacturing of multilayer laminates and have high resin filling properties between circuit patterns, thus completing the present invention.

[0011] In other words, the present invention may be configured in the following embodiments. [Embodiment 1] A film composed of a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), wherein, when the apparent melting point of the thermoplastic liquid crystal polymer film is Tm (°C), in the storage modulus profile obtained by dynamic viscoelasticity measurement, a rubbery flat region exists in the temperature range of 240°C to Tm°C, and the storage modulus E' at 280°C is 280 A thermoplastic liquid crystal polymer film having a storage modulus E' at less than 60 MPa (preferably 10 to 50 MPa, more preferably 20 to 45 MPa, and even more preferably 30 to 40 MPa). [Aspect 2] Storage modulus E' at 280°C 280A thermoplastic liquid crystal polymer film according to Embodiment 1, wherein the melting point is 30 MPa or more. [Embodiment 3] A thermoplastic liquid crystal polymer film according to Embodiment 1 or 2, wherein the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer is 300°C or higher (preferably 300 to 380°C, more preferably 305 to 360°C, and even more preferably 310 to 350°C). [Embodiment 4] A thermoplastic liquid crystal polymer film according to any one embodiment of Embodiments 1 to 3, wherein the storage modulus E' of the rubbery flat region is 10 MPa or more and less than 80 MPa (preferably 10 MPa or more and 75 MPa or less, more preferably 30 MPa or more and 70 MPa or less). [Embodiment 5] A thermoplastic liquid crystal polymer film according to any one embodiment of Embodiments 1 to 4, wherein the difference (Tm - Tm0) between the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film and the intrinsic melting point Tm0 (°C) of the thermoplastic liquid crystal polymer is -10 to +30°C (preferably -8 to +25°C, more preferably -5 to +20°C). [Aspect 6] A thermoplastic liquid crystal polymer film according to any one of aspects 1 to 5, wherein the endpoint temperature of the rubbery flat region is 280°C or higher (preferably 285°C or higher, more preferably 290°C or higher). [Aspect 7] A laminate comprising at least one layer of the thermoplastic liquid crystal polymer film according to any one of aspects 1 to 6. [Aspect 8] The laminate according to aspect 7, further comprising at least one metal layer. [Aspect 9] The laminate according to aspect 8, wherein the metal layer comprises at least one metal selected from the group consisting of copper, aluminum, nickel, iron, and silver. [Aspect 10] A molded article comprising the thermoplastic liquid crystal polymer film according to any one of aspects 1 to 6. [Aspect 11] The molded article according to aspect 10, which is a circuit board.[Aspect 12] A method for producing a thermoplastic liquid crystal polymer film according to any one of aspects 1 to 6, comprising: a heat treatment step of heat-treating a pre-heat-resistant film containing a thermoplastic liquid crystal polymer at a temperature of (Tm0-35)°C or higher and (Tm0-10)°C or lower (preferably (Tm0-30)°C or higher and (Tm0-15)°C or lower, where Tm0 (°C) is the intrinsic melting point of the thermoplastic liquid crystal polymer, for a time of 10 minutes or more and less than 60 minutes (preferably 10 minutes or more and 55 minutes, more preferably 15 minutes or more and 45 minutes, even more preferably 15 minutes or more and 30 minutes) while applying a pressure of 1.0 MPa or higher (preferably 1.5 to 10 MPa, more preferably 1.8 to 8.0 MPa, even more preferably 2.0 to 5.0 MPa); and a cooling step of cooling from the said temperature to 250°C at an average cooling rate of 20°C / min or lower (preferably 15°C / min or lower, more preferably 10°C / min or lower). [Aspect 14] A method for manufacturing a laminate according to aspect 8 or 9, comprising: a heat treatment step in which a metal layer is brought into contact with at least one surface of a pre-heat-resistant film containing a thermoplastic liquid crystal polymer, and the heat treatment is performed at a temperature of (Tm0-35)°C or higher and (Tm0-10)°C or lower (preferably (Tm0-30)°C or higher and (Tm0-15)°C or lower, where Tm0 (°C) is the intrinsic melting point of the thermoplastic liquid crystal polymer, for a time of 10 minutes or more and less than 60 minutes (preferably 10 minutes or more and 55 minutes, more preferably 15 minutes or more and 45 minutes, even more preferably 15 minutes or more and 30 minutes) while applying a pressure of 1.0 MPa or higher (preferably 1.5 to 10 MPa, more preferably 1.8 to 8.0 MPa, even more preferably 2.0 to 5.0 MPa); and a cooling step in which the temperature is cooled from the said temperature to 250°C at an average cooling rate of 20°C / min or lower (preferably 15°C / min or lower, more preferably 10°C / min or lower). [Aspect 15] A method for manufacturing a laminate according to aspect 8 or 9, wherein a metal layer is bonded directly to at least one surface of a thermoplastic liquid crystal polymer film according to any one of aspects 1 to 6, or via an adhesive layer.

[0012] In this specification, "laminated structure" refers to a structure in which an adherend is laminated onto a thermoplastic liquid crystal polymer film, and "molded structure" refers to a structure in which circuits or the like are formed on a thermoplastic liquid crystal polymer film.

[0013] As used herein, the singular forms, “a,” “an,” and “the,” are intended to include the plural form, including “at least one,” unless the context explicitly indicates otherwise. As used herein, the terms “and / or,” “at least one,” and “one or more” include any and all combinations of the related enumerated items.

[0014] Furthermore, any combination of at least two components disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more claims described in the claims is included in the present invention.

[0015] The thermoplastic liquid crystal polymer film of the present invention can suppress resin flow during the manufacturing of multilayer laminates and has high resin filling ability between circuit patterns. Therefore, for example, it can simplify the multilayer lamination process for high-density circuit boards and fine circuit boards, which have been complicated until now, and make it possible to manufacture laminates at low cost. Furthermore, it becomes possible to manufacture multilayer laminated substrates such as high-density circuit boards and fine circuit boards without using special equipment or jigs.

[0016] This is a schematic cross-sectional view of a laminate according to one aspect of the present invention. This is a schematic cross-sectional view of an assembly during the fabrication of a multilayer laminate according to one aspect of the present invention. This is a schematic cross-sectional view of an assembly during the fabrication of a circuit board according to one aspect of the present invention. This is a graph showing the temperature dependence of the storage modulus obtained by dynamic viscoelasticity measurement of a heat-treated film obtained in Example 1 of the present invention. This is a graph showing the temperature dependence of the storage modulus obtained by dynamic viscoelasticity measurement of a heat-treated film obtained in Comparative Example 2.

[0017] [Thermoplastic Liquid Crystal Polymer] In this specification, a thermoplastic liquid crystal polymer film is a film containing a thermoplastic liquid crystal polymer. The thermoplastic liquid crystal polymer is composed of a melt-mold liquid crystalline polymer (or a polymer capable of forming an optically anisotropic molten phase), and its chemical composition is not particularly limited as long as it is a melt-mold liquid crystalline polymer, but examples include thermoplastic liquid crystal polyester, or thermoplastic liquid crystal polyesteramide in which an amide bond is introduced thereto.

[0018] In this specification, the formation of an optically anisotropic molten phase can be determined, for example, by placing the sample on a hot stage, heating it in a nitrogen atmosphere, and observing the transmitted light of the sample.

[0019] Furthermore, the thermoplastic liquid crystal polymer may be a polymer in which an aromatic polyester or aromatic polyesteramide is further modified by introducing isocyanate-derived bonds such as imide bonds, carbonate bonds, carbodiimide bonds, or isocyanurate bonds.

[0020] Specific examples of thermoplastic liquid crystal polymers used in the present invention include known thermoplastic liquid crystal polyesters and thermoplastic liquid crystal polyesteramides derived from compounds classified as (1) to (4) below and their derivatives. However, it goes without saying that there is an appropriate range for the combination of various raw material compounds in order to form a polymer that can form an optically anisotropic molten phase.

[0021] (1) Aromatic or aliphatic diols (see Table 1 for representative examples)

[0022] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples)

[0023] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples)

[0024] (4) Aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids (see Table 4 for representative examples)

[0025] Typical examples of thermoplastic liquid crystal polymers obtained from these raw material compounds include copolymers having repeating units, as shown in Tables 5 and 6.

[0026]

[0027]

[0028] Of these copolymers, copolymers containing p-hydroxybenzoic acid and / or 6-hydroxy-2-naphthoic acid as at least a repeating unit are preferred, and in particular, (i) copolymers containing repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, or (ii) copolymers containing repeating units of at least one aromatic hydroxycarboxylic acid selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol and / or aromatic hydroxyamine, and at least one aromatic dicarboxylic acid are preferred.

[0029] For example, in copolymer (i), if the thermoplastic liquid crystal polymer contains repeating units of at least p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, the molar ratio (A) / (B) of p-hydroxybenzoic acid in repeating unit (A) to 6-hydroxy-2-naphthoic acid in repeating unit (B) is preferably about 10 / 90 to 90 / 10 in the thermoplastic liquid crystal polymer, more preferably about 15 / 85 to 85 / 15, and even more preferably about 20 / 80 to 80 / 20. Furthermore, from the viewpoint of melt moldability, (A) / (B) is preferably 50 / 50 to 95 / 5, and more preferably about 70 / 30 to 90 / 10. Furthermore, from the viewpoint of making it easier to form a crystal structure through heat treatment and to improve heat resistance, it is even more preferable that (A) / (B) = 75 / 25 to 90 / 10, and even more preferable that (A) / (B) = 78 / 22 to 85 / 15.

[0030] In the case of copolymer (i), in addition to the repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, repeating units composed of aromatic diols or aromatic dicarboxylic acids (e.g., terephthalic acid) may be included, from the viewpoint of adjusting the molecular weight, etc.

[0031] Furthermore, in the case of copolymer (ii), at least one aromatic hydroxycarboxylic acid (C) selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol (D) selected from the group consisting of 4,4'-dihydroxybiphenyl, hydroquinone, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether, and at least one aromatic dicarb selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid The molar ratio of acid (E) to each repeating unit in the thermoplastic liquid crystal polymer may be approximately (C):(D):(E) = (30-80):(35-10):(35-10), more preferably (C):(D):(E) = (35-75):(32.5-12.5):(32.5-12.5), and even more preferably (C):(D):(E) = (40-70):(30-15):(30-15).

[0032] Furthermore, the molar ratio of repeating units derived from 6-hydroxy-2-naphthoic acid among the aromatic hydroxycarboxylic acid (C) may be, for example, 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more. The molar ratio of repeating units derived from 2,6-naphthalenedicarboxylic acid among the aromatic dicarboxylic acid (E) may be, for example, 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more.

[0033] Further, the aromatic diol (D) may be composed of repeating units (D1) and (D2) derived from two different aromatic diols selected from the group consisting of hydroquinone, 4,4'-dihydroxybiphenyl, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether. In that case, the molar ratio of the two aromatic diols may be (D1) / (D2) = 23 / 77 to 77 / 23, more preferably 25 / 75 to 75 / 25, and even more preferably 30 / 70 to 70 / 30.

[0034] Further, the molar ratio of the repeating structural unit derived from the aromatic diol to the repeating structural unit derived from the aromatic dicarboxylic acid is preferably (D) / (E) = 95 / 100 to 100 / 95. If it is out of this range, the degree of polymerization does not increase and the mechanical strength tends to decrease.

[0035] The intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer is preferably, for example, 300°C or higher, more preferably in the range of 300 to 380°C, even more preferably in the range of 305 to 360°C, and even more preferably in the range of 310 to 350°C. The intrinsic melting point of the thermoplastic liquid crystal polymer can be obtained by observing the thermal behavior of the thermoplastic liquid crystal polymer sample using a differential scanning calorimeter, and is measured by a method different from the apparent melting point Tm of the thermoplastic liquid crystal polymer film described later. That is, after heating a thermoplastic liquid crystal polymer sample from room temperature (for example, 25°C) to 400°C at a rate of 10°C / min, cooling it to room temperature at a rate of 10°C / min, and then heating it again from room temperature to 400°C at a rate of 10°C / min, the position of the endothermic peak that appears can be determined as the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer.

[0036] Further, from the viewpoint of melt moldability, the thermoplastic liquid crystal polymer may have a melt viscosity of 20 to 120 Pa·s at a shear rate of 1000 / s at, for example, (Tm0 + 20)°C, and preferably has a melt viscosity of 30 to 100 Pa·s.

[0037] In the thermoplastic liquid crystal polymer, within a range that does not impair the effects of the present invention, thermoplastic polymers such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyether ether ketone, fluororesin, etc., and various additives may be added. Also, fillers such as organic fillers and inorganic fillers may be added as necessary. Therefore, the thermoplastic liquid crystal polymer film of the present invention includes a film made of a thermoplastic liquid crystal polymer composition containing a thermoplastic liquid crystal polymer as a main component and at least one or more of these sub-components such as different polymers, additives, fillers, etc.

[0038] The thermoplastic liquid crystal polymer film may contain 50% by weight or more of the thermoplastic liquid crystal polymer, preferably 80% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more, and even more preferably 98% by weight or more, and may contain 100% by weight.

[0039] [Method for producing thermoplastic liquid crystal polymer film, laminate or molded body] The thermoplastic liquid crystal polymer film of the present invention is subjected to heat treatment for 10 minutes or more and less than 60 minutes while applying a pressure of 1.0 MPa or more at a temperature of (Tm0 - 35) °C or more and (Tm0 - 10) °C or less to the thermoplastic liquid crystal polymer film (film before heat resistance improvement) composed of the thermoplastic liquid crystal polymer, and is cooled at an average cooling rate of 20 °C / min or less from that temperature to 250 °C, whereby it can be produced.

[0040] The thermoplastic liquid crystal polymer film (pre-heat-resistant film) may be a cast film of the above-mentioned thermoplastic liquid crystal polymer or thermoplastic liquid crystal polymer composition, or it may be a film obtained by extruding a molten kneaded mixture of the thermoplastic liquid crystal polymer or thermoplastic liquid crystal polymer composition. In this case, any extrusion molding method can be used, but the well-known T-die film-forming stretching method, laminate stretching method, inflation method, etc., are industrially advantageous. In particular, with the inflation method, stress is applied not only in the mechanical axis direction (hereinafter abbreviated as MD) of the thermoplastic liquid crystal polymer film but also in the direction perpendicular to it (hereinafter abbreviated as TD), allowing for uniform stretching in MD and TD. As a result, a thermoplastic liquid crystal polymer film (pre-heat-resistant film) with controlled molecular orientation and dielectric properties in MD and TD can be obtained.

[0041] Furthermore, the thermoplastic liquid crystal polymer film (film before heat treatment) may be stretched as needed after extrusion molding. The stretching method itself is well known, and either biaxial stretching or uniaxial stretching may be used, but biaxial stretching is preferred because it is easier to control the degree of molecular orientation. In addition, known uniaxial stretchers, simultaneous biaxial stretchers, sequential biaxial stretchers, etc., can be used for stretching.

[0042] For example, in extrusion molding using the T-die method, the molten sheet extruded from the T-die may be stretched not only along the medium-density (MD) but also simultaneously along both the medium-density (TD) and the tangential (TD) of the thermoplastic liquid crystal polymer film to form a film, or the molten sheet extruded from the T-die may be stretched first along the MD and then along the TD to form a film.

[0043] Furthermore, in inflation extrusion molding, a cylindrical sheet extruded from a ring die may be stretched at a predetermined draw ratio (corresponding to the stretching ratio of MD) and blow ratio (corresponding to the stretching ratio of TD) to form a film.

[0044] Furthermore, if necessary, known or conventional heat treatments may be performed to adjust the thermal expansion coefficient of the thermoplastic liquid crystal polymer film (film before heat treatment). The heat treatment conditions can be set appropriately according to the purpose. For example, the thermal expansion coefficient may be increased by heating at a temperature of (Tm0 - 15)°C or higher and less than (Tm0)°C relative to the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer for 5 to 60 seconds (for example, 10 to 30 seconds). Note that the heat treatment for adjusting the thermal expansion coefficient differs from the heat treatment for heat resistance described later in terms of purpose and corresponding heat treatment conditions.

[0045] The thermoplastic liquid crystal polymer film (pre-heat-resistant film) obtained in this manner is subjected to heat treatment to make it heat-resistant. From the viewpoint of adjusting it to exhibit specific dynamic viscoelastic properties, if the intrinsic melting point of the thermoplastic liquid crystal polymer constituting the thermoplastic liquid crystal polymer film is Tm0 (°C), it is preferable to perform heat treatment for a time of 10 minutes to less than 60 minutes at a temperature of (Tm0 - 35)°C or higher and (Tm0 - 10)°C or lower while applying a pressure of 1.0 MPa or higher, and then cool it from that temperature to 250°C at an average cooling rate of 20°C / min or less. In the present invention, it is not necessarily required to increase the apparent melting point Tm by heat treatment, and by making it heat-resistant by causing a rubbery flat region in the high-temperature range, and by setting heat treatment conditions that prevent the storage modulus at high temperatures from becoming too high, a thermoplastic liquid crystal polymer film exhibiting specific dynamic viscoelastic properties can be obtained.

[0046] From the viewpoint of developing a rubbery flat region in the high-temperature range, the heat treatment temperature is preferably (Tm0-35)°C or higher, and more preferably (Tm0-30)°C or higher. For example, the lower limit of the heat treatment temperature may be within the above range, as well as 260°C or higher (preferably 270°C or higher, more preferably 280°C or higher). Furthermore, from the viewpoint of adjusting so that the storage modulus at high temperatures does not become too high, it is preferably (Tm0-10)°C or lower, and more preferably (Tm0-15)°C or lower. For example, the upper limit of the heat treatment temperature may be within the above range, as well as 350°C or lower (preferably 340°C or lower, more preferably 330°C or lower).

[0047] The heat treatment time varies depending on the heat treatment temperature, but from the viewpoint of developing a rubbery flat region in the high-temperature range, it is preferably 10 minutes or more, and more preferably 15 minutes or more. Furthermore, from the viewpoint of adjusting so that the storage modulus at high temperatures does not become too high, it is preferably less than 60 minutes, more preferably 55 minutes or less, even more preferably 45 minutes or less, and even more preferably 30 minutes or less.

[0048] Applying pressure in the thickness direction of the thermoplastic liquid crystal polymer film while heat treatment is preferable from the viewpoint of optimizing dynamic viscoelastic properties, possibly because it allows for adjustment of the crystal structure. The heat treatment pressure is preferably 1.0 MPa or higher, more preferably 1.5 MPa or higher, even more preferably 1.8 MPa or higher, and even more preferably 2.0 MPa or higher. There is no particular upper limit to the heat treatment pressure, but for example, it may be 10 MPa or lower, 8.0 MPa or lower, or 5.0 MPa or lower.

[0049] It is preferable to slow the cooling rate when cooling from the above heat treatment temperature to promote crystal growth. The average cooling rate from the above heat treatment temperature to 250°C is preferably 20°C / min or less, more preferably 15°C / min or less, and even more preferably 10°C / min or less. The lower limit of the average cooling rate from the above heat treatment temperature to 250°C is not particularly limited, but from the viewpoint of productivity, it may be 1°C / min or more. Furthermore, the cooling may be performed while maintaining the above pressure, or while releasing the pressure. From the viewpoint of adjusting the crystal structure, it is preferable to cool while maintaining the pressure.

[0050] The heat treatment apparatus is not particularly limited as long as it can heat under pressure for a certain period of time, and can be a single-wafer heating and pressing device such as a hot press, or a continuous heating and pressing device such as a double-belt press. Known or conventional heat sources can be used as the heat source during heat treatment. Preferred heat sources include, for example, a hot air oven, a steam oven, an electric heater, an infrared heater, a ceramic heater, a hot roll, a hot press, and an electromagnetic wave irradiator (e.g., a microwave irradiator). These heat sources may be used individually or in combination of two or more.

[0051] Heat treatment for heat resistance can be performed in one or multiple stages, but in the thermoplastic liquid crystal polymer film of the present invention, it is preferable to perform the heat treatment in one or two stages, and more preferably in one stage from the viewpoint of adjusting so that the storage modulus at high temperatures does not become too high. In a one-stage heat treatment, heat resistance is achieved by the first heat treatment alone, and in a multi-stage heat treatment, the heat treatment temperature of the next stage after the first heat treatment may be higher than the heat treatment temperature of the previous stage. The apparent melting point Tm of the thermoplastic liquid crystal polymer film increases with heat treatment, but the heating temperature can be determined based on the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer. Therefore, the heating temperature from the second heat treatment onward may be at or above the intrinsic melting point Tm0°C of the thermoplastic liquid crystal polymer as needed, and for example, the highest temperature reached in a multi-stage heat treatment may be (Tm0 + 30)°C or less, and preferably (Tm0 + 20)°C or less.

[0052] The heat treatment method is not particularly limited as long as the heat-resistant thermoplastic liquid crystal polymer film has specific dynamic viscoelastic properties. For example, the thermoplastic liquid crystal polymer film (film before heat treatment) may be heat-treated directly, or the thermoplastic liquid crystal polymer film (film before heat treatment) may be heat-treated while laminated with a substrate, or the laminate obtained by laminating the thermoplastic liquid crystal polymer film (film before heat treatment) and the substrate may be heat-treated. Such a laminate can be manufactured using thermocompression bonding methods such as hot press, hot roll, or double belt press, but is not particularly limited thereto. The thermoplastic liquid crystal polymer film may be used as a laminate while laminated with the substrate, or it may be separated from the substrate after heat treatment and used as a thermoplastic liquid crystal polymer film alone.

[0053] The adherend is not particularly limited as long as it can be used as a support for heat treatment, and examples include metal layers and heat-resistant resin layers.

[0054] The metals constituting the metal layer are not particularly limited as long as they are conductive metals, but examples include copper, copper alloys, aluminum, aluminum alloys, nickel, nickel alloys, iron, iron alloys, silver, silver alloys, and composite metal species thereof. Preferably, the layer contains at least one metal selected from the group consisting of copper, aluminum, nickel, iron, and silver. These metals may also contain other metal species in amounts of 2000 ppm by mass or less, and unavoidable impurities may be present.

[0055] When a metal layer is used as the substrate, the thermoplastic liquid crystal polymer film portion can be used as is after heat treatment as a heat-resistant laminate. For example, if conductivity and heat dissipation are required, copper, copper alloys, silver, or silver alloys can be used; if ferromagnetism is required, iron alloys can be used; and if an inexpensive material is needed, aluminum can be used.

[0056] Preferably, copper may be used as the metal species for the circuit board. Specifically, the metal layer may consist of copper containing 99.8% by mass or more, and further comprising 2000 ppm by mass or less of at least one other metal species selected from the group consisting of silver, tin, zinc, chromium, boron, titanium, magnesium, phosphorus, silicon, iron, gold, praseodymium, nickel, and cobalt, with the remainder being unavoidable impurities.

[0057] As a method for forming a metal layer on a thermoplastic liquid crystal polymer film, known methods can be used, and a laminate can be manufactured by bonding the metal layer directly or via an adhesive layer to at least one surface of the thermoplastic liquid crystal polymer film. Examples of adhesive layers include polyphenylene ether, epoxy resin, polyurethane, thermoplastic polyimide, and polyetherimide. In the case of direct bonding, the metal layer may be formed by vapor deposition, sputtering, electroless plating, electrolytic plating, etc. Alternatively, a metal foil (e.g., copper foil) may be laminated onto the surface of the thermoplastic liquid crystal polymer film by thermocompression bonding. The copper foil is not particularly limited as long as it is copper foil that can be used in circuit boards, and may be rolled copper foil or electrolytic copper foil.

[0058] Examples of resins constituting the heat-resistant resin layer include resins having a melting point higher than the maximum temperature achievable during heat treatment, or thermosetting resins. Preferably, these include polyimide, polyphenylene ether, polyphenylene sulfide, and fluororesin (e.g., polytetrafluoroethylene).

[0059] Known methods can be used to form a heat-resistant resin layer on a thermoplastic liquid crystal polymer film. For example, a heat-resistant resin film may be laminated onto the surface of the thermoplastic liquid crystal polymer film by thermocompression bonding.

[0060] The thermoplastic liquid crystal polymer film of the present invention can be used as a laminate containing at least one layer thereof. The laminate of the present invention may be manufactured by laminating an adherend to at least one surface of a heat-treated thermoplastic liquid crystal polymer film, or by heat-treating a thermoplastic liquid crystal polymer film (film before heat treatment) with an adherend already laminated to at least one surface. Lamination with the adherend can be performed directly on at least one surface of the thermoplastic liquid crystal polymer film or via an adhesive layer. Examples of adhesive layers include polyphenylene ether, epoxy resin, polyurethane, thermoplastic polyimide, and polyetherimide.

[0061] In particular, laminates including a metal layer as the adherend can be used as metal-clad laminates and the like, which are materials for manufacturing molded products (such as circuit boards). For example, in one embodiment of the present invention, a laminate comprising at least one layer of thermoplastic liquid crystal polymer film and at least one layer of metal can be manufactured by heat-treating the film containing the thermoplastic liquid crystal polymer with the metal layer in contact with at least one surface of the film, applying a pressure of 1.0 MPa or more at a temperature of (Tm0-35)°C or higher and (Tm0-10)°C for a period of 10 minutes or more and less than 60 minutes, and then cooling from that temperature to 250°C at an average cooling rate of 20°C / min or less. The heat treatment and cooling can be carried out according to the various heat treatment and cooling conditions described above.

[0062] Furthermore, in another embodiment of the present invention, a laminate comprising at least one thermoplastic liquid crystal polymer film and at least one metal layer can be manufactured by bonding the metal layer directly or via an adhesive layer to at least one surface of the thermoplastic liquid crystal polymer film after heat treatment.

[0063] In the laminate of the thermoplastic liquid crystal polymer film and the metal layer, if the thickness of each single layer is Ta (μm) and Tb (μm), then Ta and Tb can be selected from the range of 0.1 to 500 μm, respectively. From the viewpoint of thinning and weight reduction in recent years, Ta may preferably be 1 to 175 μm, more preferably 5 to 130 μm. Also, Tb may preferably be 1 to 20 μm, more preferably 2 to 15 μm.

[0064] The laminate may have a multilayer structure of a thermoplastic liquid crystal polymer film and a metal layer, and may include at least one thermoplastic liquid crystal polymer film and at least one metal layer. For example, examples of multilayer laminates include, but are not limited to, the following: (i) metal layer / thermoplastic liquid crystal polymer film (ii) metal layer / thermoplastic liquid crystal polymer film / metal layer (iii) thermoplastic liquid crystal polymer film / thermoplastic liquid crystal polymer film / metal layer (iv) thermoplastic liquid crystal polymer film / metal layer / thermoplastic liquid crystal polymer film (v) metal layer / thermoplastic liquid crystal polymer film / thermoplastic liquid crystal polymer film / metal layer (vi) metal layer / thermoplastic liquid crystal polymer film / metal layer / thermoplastic liquid crystal polymer film / metal layer.

[0065] A molded article containing the thermoplastic liquid crystal polymer film of the present invention may be manufactured by post-processing the thermoplastic liquid crystal polymer film and / or laminate.

[0066] For example, a molded body (or unit circuit board) such as a wiring board may be manufactured by forming a conductive pattern on the surface of a thermoplastic liquid crystal polymer film, or a molded body (or unit circuit board) such as a wiring board may be manufactured by forming a conductive pattern on a metal layer of a laminate. Furthermore, a molded body (or circuit board) such as a wiring board may be manufactured by layering unit circuit boards on which conductive patterns have been formed onto other substrate materials to create a multilayer structure. Examples of substrate materials include the thermoplastic liquid crystal polymer film, metal layer (metal foil), and unit circuit board mentioned above, and an adhesive layer may be used as needed.

[0067] Alternatively, a pre-molded body comprising a polymer layer composed of a thermoplastic liquid crystal polymer may be used to obtain a molded body by performing the heat treatment described above on the pre-molded body. In this case, the polymer portion of the molded body has specific dynamic viscoelastic properties, which will be described later.

[0068] [Thermoplastic liquid crystal polymer film, laminate and molded article] The thermoplastic liquid crystal polymer film of the present invention has a rubbery flat region in the storage modulus profile determined by dynamic viscoelasticity measurement in the temperature range of 240°C or above and below the apparent melting point Tm°C, and the storage modulus E' at 280°C. 280 The pressure is less than 60 MPa.

[0069] Here, the rubbery flat region refers to a region in which the polymer molecular chains move but do not completely melt, and in which the storage modulus is independent of temperature and takes on a substantially constant value. In this specification, the storage modulus at a given temperature is considered to belong to the flat region if the absolute value of the slope calculated from the change in the common logarithm of the storage modulus (MPa) in a temperature range of ±5°C of the given temperature is 0.015 / °C or less. The existence of a rubbery flat region in a given temperature range (for example, 240°C or higher and below the apparent melting point Tm°C) means that the entire rubbery flat region belongs to the temperature range of the given temperature, that is, the starting temperature of the rubbery flat region is 240°C or higher and the ending temperature is below the apparent melting point Tm°C. The thermoplastic liquid crystal polymer film of the present invention has a rubbery flat region in a temperature range of 240°C or higher and below the apparent melting point Tm°C, and its starting temperature may preferably be 250°C or higher. Furthermore, the endpoint temperature of the rubbery flat region may be below the apparent melting point Tm°C and 350°C or less, preferably 330°C or less, and more preferably 300°C or less. The region where the absolute value of the above slope exceeds 0.015 / °C on the high-temperature side and the storage modulus decreases sharply is defined as the flow region.

[0070] The thermoplastic liquid crystal polymer film of the present invention has a rubbery flat region in the high-temperature range of its storage modulus, and its storage modulus E' at 280°C. 280The viscosity is low in a specific range. In other words, because a rubbery, flat region exists in the low viscosity range, it is possible to achieve stable lamination at lower viscosity compared to conventional methods, and it was found that resin flow can be suppressed during the manufacturing of multilayer laminates. Furthermore, it was found that the storage modulus at high temperatures does not show a high value as in conventional methods, but rather a specific low value, which may make the thermoplastic liquid crystal polymer film more deformable during lamination, resulting in high resin filling ability between circuit patterns.

[0071] The thermoplastic liquid crystal polymer film of the present invention has a storage modulus E' at 280°C. 280 The pressure is less than 60 MPa. From the viewpoint of suppressing resin flow during laminate fabrication, for example, it may be 10 MPa or more, preferably 20 MPa or more, and more preferably 30 MPa or more. On the other hand, from the viewpoint of improving the resin filling properties between circuit patterns in fine circuits, the storage modulus E' at 280°C is used. 280 The upper limit is preferably 50 MPa or less, more preferably 45 MPa or less, and even more preferably 40 MPa or less.

[0072] Furthermore, from the viewpoint of suppressing resin flow during laminate fabrication, the storage modulus E' of the rubbery flat region may preferably be 10 MPa or more, more preferably 30 MPa or more. The upper limit of the storage modulus E' of the rubbery flat region may be, for example, less than 80 MPa, preferably 75 MPa or less, more preferably 70 MPa or less. In this specification, the storage modulus E' of the rubbery flat region is the storage modulus at the temperature at which the absolute value of the slope in the rubbery flat region is at its minimum, and is a value measured by the method described in the examples below.

[0073] The thermoplastic liquid crystal polymer film of one embodiment of the present invention may have an endpoint temperature of 280°C or higher in the rubbery flat region, preferably 285°C or higher, and more preferably 290°C or higher, from the viewpoint of excellent heat resistance. In this specification, the endpoint temperature of the rubbery flat region is a value measured by the method described in the examples below.

[0074] In the thermoplastic liquid crystal polymer film of one embodiment of the present invention, the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer constituting the thermoplastic liquid crystal polymer film is preferably, for example, 300°C or higher, more preferably in the range of 300 to 380°C, even more preferably in the range of 305 to 360°C, and even more preferably in the range of 310 to 350°C. The intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer constituting the thermoplastic liquid crystal polymer film can be measured using a differential scanning calorimeter, following the measurement procedure described above, with the thermoplastic liquid crystal polymer film sample as the object of measurement.

[0075] The apparent melting point Tm of the thermoplastic liquid crystal polymer film may be, for example, 310°C or higher, preferably 315 to 380°C, more preferably 318 to 370°C, and even more preferably 320 to 360°C. The apparent melting point Tm of the thermoplastic liquid crystal polymer film can be obtained by observing the thermal behavior of the thermoplastic liquid crystal polymer film sample using a differential scanning calorimeter. Specifically, the position of the endothermic peak that appears when the thermoplastic liquid crystal polymer film sample is heated from room temperature (e.g., 25°C) at a rate of 10°C / min can be determined as the apparent melting point Tm of the thermoplastic liquid crystal polymer film.

[0076] In one embodiment of the present invention, the thermoplastic liquid crystal polymer film may exhibit different values ​​for the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film and the intrinsic melting point Tm0 (°C) of the thermoplastic liquid crystal polymer, depending on the crystal structure formed by heat treatment. For example, the difference (Tm - Tm0) between the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film and the intrinsic melting point Tm0 (°C) of the thermoplastic liquid crystal polymer is preferably -10 to +30°C, more preferably -8 to +25°C, and even more preferably -5 to +20°C.

[0077] The thickness of the thermoplastic liquid crystal polymer film can be set appropriately depending on the application. For example, when considering its use as a material for the insulating layer of a circuit board, it may be 10 to 500 μm, preferably 15 to 250 μm, more preferably 20 to 200 μm, and even more preferably 25 to 150 μm.

[0078] The thermoplastic liquid crystal polymer film of the present invention has excellent heat resistance and can therefore be suitably used in various applications.

[0079] For example, a laminate comprising a thermoplastic liquid crystal polymer film and a metal layer on at least one of its surfaces can be used as a metal-clad laminate, which is a material for manufacturing molded articles (such as circuit boards). The metal-clad laminate may be a single-sided metal-clad laminate having a metal layer on one side of the thermoplastic liquid crystal polymer film, or a double-sided metal-clad laminate having metal layers on both sides of the thermoplastic liquid crystal polymer film. The metal-clad laminate may be formed by laminating the thermoplastic liquid crystal polymer film and the metal layer via an adhesive layer (e.g., an adhesive), but from the viewpoint of reducing the thickness for use as a circuit board manufacturing material, it is preferable to have a metal-clad laminate in which the thermoplastic liquid crystal polymer film and the metal layer are directly laminated without an adhesive layer.

[0080] The metal-clad laminate may have a metal layer containing the above-mentioned metal species laminated on it. The metal layer may be formed by bonding metal foil by thermocompression as described above, or by sputtering, vapor deposition, electroless plating, etc. The thickness of the metal layer can be appropriately set according to the application of the metal-clad laminate, etc. For example, it can be selected from a wide range of 10 nm to 100 μm. For example, when metal foil is used as the metal layer, the thickness of the metal layer may be 1 to 100 μm, preferably 5 to 50 μm, and more preferably 8 to 35 μm. Also, when the metal layer is formed by sputtering, vapor deposition, electroless plating, etc., the thickness of the metal layer may be 10 nm to 35 μm, preferably 50 nm to 12 μm, and more preferably 100 nm to 9 μm.

[0081] Furthermore, the molded body may be a circuit board comprising a thermoplastic liquid crystal polymer film as an insulating layer and a circuit layer. For example, a circuit board can be manufactured by forming a conductive pattern on the surface of the thermoplastic liquid crystal polymer film described above. Alternatively, a circuit board can be manufactured by processing a metal layer on the metal-clad laminate described above to form a wiring circuit. Known methods can be used for circuit processing; for example, circuits may be formed by etching the metal layer on the film using a subtractive method.

[0082] The circuit board can be used as various high-frequency circuit boards. Furthermore, the circuit board may be a circuit board (or semiconductor element mounting board) on which semiconductor elements (e.g., IC chips) are mounted. Also, because the dielectric loss tangent of the circuit board is controlled to be low, it may be used in various transmission lines, such as coaxial lines, strip lines, microstrip lines, coplanar lines, and parallel lines, as well as in antennas (e.g., microwave or millimeter-wave antennas). The circuit board may also be used in antenna devices where the antenna and transmission line are integrated. For example, it may be used in various sensors, particularly in automotive radar.

[0083] Examples of antennas include waveguide slot antennas, horn antennas, lens antennas, printed antennas, triplate antennas, microstrip antennas, and patch antennas, which utilize millimeter waves or microwaves.

[0084] When a molded body has multiple circuit layers, it can meet the requirements for high density and high functionality, making the molded body suitable as a multilayer circuit board.

[0085] The thermoplastic liquid crystal polymer film, laminate, and molded article of the present invention have remarkably high heat resistance and can be effectively used as components in the electrical and electronic fields, office equipment and precision equipment fields, power semiconductor fields, etc., such as circuit board materials. They are suitable for applications such as high-frequency circuit boards, automotive sensors, mobile device circuit boards, and antennas, but are not limited to these.

[0086] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, various physical properties were measured by the following methods.

[0087] (Film thickness) Using a digital thickness gauge (manufactured by Mitutoyo Corporation), the obtained thermoplastic liquid crystal polymer film was measured at intervals of 1 cm in the TD direction, and the average value of 10 points arbitrarily selected from the central part and the end part was taken as the film thickness.

[0088] (Apparent melting point Tm of thermoplastic liquid crystal polymer film) Using a differential scanning calorimeter (manufactured by Shimadzu Corporation), a predetermined size was sampled from the thermally treated thermoplastic liquid crystal polymer films obtained in the examples and comparative examples and placed in a sample container. The position of the endothermic peak that appeared when the temperature was raised from room temperature to 400 °C at a rate of 10 °C / min was taken as the apparent melting point Tm of the thermoplastic liquid crystal polymer film.

[0089] (True melting point Tm0 of thermoplastic liquid crystal polymer) Using a differential scanning calorimeter (manufactured by Shimadzu Corporation), a predetermined size was sampled from the thermally treated thermoplastic liquid crystal polymer films obtained in the examples and comparative examples and placed in a sample container. After the temperature was raised from room temperature to 400 °C at a rate of 10 °C / min, it was cooled from room temperature to room temperature at a rate of 10 °C / min, and then the position of the endothermic peak that appeared when the temperature was raised from room temperature to 400 °C at a rate of 10 °C / min again was taken as the true melting point Tm0 of the thermoplastic liquid crystal polymer constituting the thermoplastic liquid crystal polymer film.

[0090] (Dynamic viscoelasticity measurement) (Storage modulus E') 280 ) The thermally treated thermoplastic liquid crystal polymer films obtained in the examples and comparative examples were cut into pieces with a length of 10 mm and a width of 5 mm to prepare test pieces. Using a viscoelasticity measuring device ("DMA242E Artemis" manufactured by NETZSCH), the test piece was attached to a sample holder, the frequency was 1 Hz, the load was 0.2 N, the measurement mode was the tensile mode, and the storage modulus was measured at a temperature range from room temperature to 350 °C at a heating rate of 5 °C / min. The storage modulus at 280 °C was taken as the storage modulus E' 280 and designated as such.

[0091] (Presence or absence of a rubbery flat region) In the obtained storage modulus profile (vertical axis: storage modulus (MPa), horizontal axis: temperature (°C)), the slope was calculated from the change in the common logarithm of the storage modulus for each temperature in 10°C increments between 240°C and 300°C, within a temperature range of ±5°C. In the temperature range above 240°C and below the apparent melting point (Tm), if there was a temperature at which the absolute value of the calculated slope was 0.015 / °C or less, it was determined that a rubbery flat region existed; otherwise, it was determined that a rubbery flat region did not exist.

[0092] (Storage modulus E' of the rubbery flat region) If a rubbery flat region exists, the storage modulus E' of the rubbery flat region was calculated as the storage modulus E' of the rubbery flat region, which is the temperature at which the absolute value of the calculated slope is minimized.

[0093] (End point temperature of the rubbery flat region) The temperature at the intersection of the tangent to the rubbery flat region, which exists at a temperature of 240°C or higher, and the tangent to the region on the lower temperature side of the rubbery flat region was calculated as the starting point temperature of the rubbery flat region, and the temperature at the intersection of the tangent to the rubbery flat region and the tangent to the flow region on the higher temperature side of the rubbery flat region was calculated as the end point temperature of the rubbery flat region.

[0094] (Lamination Flow) The heat resistance due to lamination flow (suppression of resin flow) was evaluated by observing the shape change of the thermoplastic liquid crystal polymer film at the four corners of the multilayer laminate. As shown in Figure 1, a laminate 3 was used to evaluate the lamination flow by stacking a thermoplastic liquid crystal polymer film 1 and a metal foil 2 using the method described in the manufacturing example below. As shown in Figure 2, two laminates 3 obtained in Figure 1 were stacked so that the thermoplastic liquid crystal polymer films 1 of each were facing each other to create an assembly. A SUS plate 4 and a cushioning material 5 were placed on the upper and lower surfaces of this assembly, respectively, and the assembly was sandwiched between them. A multilayer laminate was produced by heat-pressing in a vacuum press at 310°C and a surface pressure of 2 MPa. The shape change of the thermoplastic liquid crystal polymer film at the four corners of the fabricated multilayer laminate was observed visually and evaluated according to the following criteria. A: In the obtained multilayer laminate, the thermoplastic liquid crystal polymer hardly flowed, and only burrs of 1.0 mm or less were observed from the metal layer. B: In the obtained multilayer laminate, burrs larger than 1.0 mm were observed from the metal layer due to the flow of the thermoplastic liquid crystal polymer.

[0095] (Filling capacity into fine circuits) The filling capacity into fine circuits was evaluated by observing the shape change of the thermoplastic liquid crystal polymer film in the cross-section of the multilayer laminate with line-and-space circuits. As shown in Figure 3, a laminate 6 was fabricated by processing a circuit with a line-and-space of 10 μm / 10 μm on the metal layer 2 of the laminate 3 obtained in Figure 1. An assembly was fabricated by overlapping the circuit-processed surface of laminate 6 with the thermoplastic liquid crystal polymer film 1 of another laminate 3. A SUS plate 4 and a cushioning material 5 were placed on the upper and lower surfaces of this assembly, respectively, and the assembly was sandwiched between them. A multilayer laminate was fabricated by thermocompression bonding in a vacuum press at 310°C and a surface pressure of 2 MPa. The shape change of the thermoplastic liquid crystal polymer film in the cross-section of the fabricated multilayer laminate was observed visually and evaluated according to the following criteria. A: In the obtained multilayer laminate, the thermoplastic liquid crystal polymer was sufficiently filled, and no voids were observed in the space between circuits. B: In the resulting multilayer laminate, the thermoplastic liquid crystal polymer was not sufficiently filled, and voids were observed in the spaces between circuits.

[0096] <Manufacturing Example 1> [Preparation of Thermoplastic Liquid Crystal Polymer Film (Pre-heat Resistance Film)] A copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (molar ratio: 80 / 20) was heated and kneaded in an extruder at 280 to 340°C, and then extruded through an inflation die with a diameter of 40 mm and a slit spacing of 0.6 mm to obtain a thermoplastic liquid crystal polymer film (pre-heat resistance film) with a thickness of 50 μm.

[0097] [Fabrication of Laminates] The obtained thermoplastic liquid crystal polymer film (film before heat treatment) and copper foil (JX Metals Corporation, "JXEFL-BHM", 12 μm thick) were laminated using the roll-to-roll method. During lamination, a heated metal roll and a heat-resistant rubber roll were used, and the surface temperature of the heated metal roll was set to 280°C. The pressure applied to the thermoplastic liquid crystal polymer film and copper foil between the heat-resistant rubber roll and the heated metal roll was 40 kg / cm² in terms of surface pressure. 2 The settings were adjusted, and under these conditions, the thermoplastic liquid crystal polymer film was first moved along a heat-resistant rubber roll, and then the copper foil was temporarily bonded to the thermoplastic liquid crystal polymer film to create a laminate.

[0098] <Example 1> The laminate from Manufacturing Example 1 was heat-treated in a press at 310°C under a pressure of 2 MPa for 30 minutes. Then, it was cooled by adjusting the average cooling rate from 310°C to 250°C to 10°C / min, obtaining a laminate in which a thermoplastic liquid crystal polymer film was laminated on a support (copper foil). The copper foil was removed from the obtained laminate by etching, and various melting point measurements and dynamic viscoelasticity measurements of the thermoplastic liquid crystal polymer film were performed. Furthermore, the heat resistance and filling ability into microcircuits were evaluated for the obtained laminate by lamination flow. The results are shown in Table 7. Figure 4 is a graph showing the temperature dependence of the storage modulus of the thermoplastic liquid crystal polymer film obtained in Example 1 by dynamic viscoelasticity measurement. A rubbery flat region exists, with a starting temperature of 257°C and an ending temperature of 296°C. The storage modulus E' in the rubbery flat region represents the storage modulus value at 280°C.

[0099] <Example 2> The laminate from Manufacturing Example 1 was heat-treated in a press at 310°C under a pressure of 2 MPa for 45 minutes. Then, it was cooled by adjusting the average cooling rate from 310°C to 250°C to 15°C / min, thereby obtaining a laminate in which a thermoplastic liquid crystal polymer film was laminated on a support (copper foil). The copper foil was removed from the obtained laminate by etching, and the thermoplastic liquid crystal polymer film was evaluated by various melting point measurements and dynamic viscoelasticity measurements. In addition, the heat resistance and filling ability into microcircuits of the obtained laminate were evaluated by lamination flow. The results are shown in Table 7. In the dynamic viscoelasticity measurement, a rubbery flat region existed, with an initial temperature of 258°C and an end temperature of 297°C. The storage modulus E' in the rubbery flat region represents the value of the storage modulus at 280°C.

[0100] <Example 3> The laminate from Manufacturing Example 1 was heat-treated in a press at 300°C under a pressure of 2 MPa for 30 minutes. Then, it was cooled by adjusting the average cooling rate from 300°C to 250°C to 5°C / min, thereby obtaining a laminate in which a thermoplastic liquid crystal polymer film was laminated on a support (copper foil). The copper foil was removed from the obtained laminate by etching, and various melting point measurements and dynamic viscoelasticity measurements of the thermoplastic liquid crystal polymer film were performed to evaluate it. In addition, the heat resistance and filling ability into microcircuits of the obtained laminate were evaluated by lamination flow. The results are shown in Table 7. In the dynamic viscoelasticity measurement, a rubbery flat region existed, with an initial temperature of 245°C and an end temperature of 288°C. Furthermore, the storage modulus E' in the rubbery flat region represents the value of the storage modulus at 260°C.

[0101] <Comparative Example 1> The laminate of Manufacturing Example 1 was evaluated without heat treatment. For the laminate of Manufacturing Example 1, the copper foil was removed by etching, and various melting point measurements and dynamic viscoelasticity measurements of the thermoplastic liquid crystal polymer film were performed. In addition, the heat resistance and filling ability into microcircuits of the laminate were evaluated by lamination flow. The results are shown in Table 7. In the dynamic viscoelasticity measurement, no rubbery flat region of the storage modulus was detected in the temperature range of 240°C or above and below the apparent melting point Tm°C.

[0102] <Comparative Example 2> The laminate from Manufacturing Example 1 was heat-treated in a press at 320°C under a pressure of 2 MPa for 30 minutes. Then, it was cooled by adjusting the average cooling rate from 320°C to 250°C to 250°C at 25°C / min to obtain a laminate in which a thermoplastic liquid crystal polymer film was laminated on a support (copper foil). The copper foil was removed from the obtained laminate by etching, and various melting point measurements and dynamic viscoelasticity measurements of the thermoplastic liquid crystal polymer film were performed to evaluate it. In addition, the heat resistance and filling ability into microcircuits of the obtained laminate were evaluated by lamination flow. The results are shown in Table 7. Figure 5 is a graph showing the temperature dependence of the storage modulus measured by dynamic viscoelasticity of the thermoplastic liquid crystal polymer film obtained in Comparative Example 2. As shown in this figure, in the dynamic viscoelasticity measurement, no rubbery flat region of the storage modulus was detected in the temperature range of 240°C or above and below the apparent melting point Tm°C.

[0103] <Comparative Example 3> The laminate from Manufacturing Example 1 was heat-treated in a press at 300°C under a pressure of 2 MPa for 80 minutes. Then, it was cooled by adjusting the average cooling rate from 300°C to 250°C to 30°C / min, thereby obtaining a laminate in which a thermoplastic liquid crystal polymer film was laminated on a support (copper foil). The copper foil was removed from the obtained laminate by etching, and various melting point measurements and dynamic viscoelasticity measurements of the thermoplastic liquid crystal polymer film were performed to evaluate it. In addition, the heat resistance and filling ability into microcircuits of the obtained laminate were evaluated by lamination flow. The results are shown in Table 7. In the dynamic viscoelasticity measurement, a rubbery flat region existed, with an initial temperature of 228°C and an end temperature of 283°C. The storage modulus E' in the rubbery flat region represents the value of the storage modulus at 240°C.

[0104] <Comparative Example 4> The laminate from Manufacturing Example 1 was heat-treated in a press at 315°C under a pressure of 2 MPa for 60 minutes. Then, it was cooled by adjusting the average cooling rate from 310°C to 250°C to 30°C / min, thereby obtaining a laminate in which a thermoplastic liquid crystal polymer film was laminated on a support (copper foil). The copper foil was removed from the obtained laminate by etching, and various melting point measurements and dynamic viscoelasticity measurements of the thermoplastic liquid crystal polymer film were performed to evaluate it. In addition, the heat resistance and filling ability into microcircuits of the obtained laminate were evaluated by lamination flow. The results are shown in Table 7. In the dynamic viscoelasticity measurement, a rubbery flat region existed, with an initial temperature of 244°C and an end temperature of 292°C. The storage modulus E' in the rubbery flat region represents the value of the storage modulus at 260°C.

[0105]

[0106] As shown in Table 7, Examples 1 to 3, in which a rubbery flat region exists above 240°C and below the apparent melting point Tm°C, and the storage modulus at 280°C is within a specific range, show good results in both heat resistance due to lamination flow (suppression of resin flow) and filling ability into microcircuits. In contrast, Comparative Examples 1 and 2, in which the rubbery flat region does not exist, show low heat resistance due to lamination flow because the resin flows during the manufacturing of the multilayer laminate. Furthermore, Comparative Examples 3 and 4, in which the storage modulus at 280°C is not within a specific range, show low filling ability into microcircuits.

[0107] The thermoplastic liquid crystal polymer film of the present invention can suppress resin flow during the manufacturing of multilayer laminates and has high resin filling ability between circuit patterns. Therefore, for example, it can simplify the multilayer lamination process for high-density circuit boards and fine circuit boards, which has been complicated until now, and make it possible to manufacture laminates at low cost. Furthermore, it becomes possible to manufacture multilayer laminated substrates of high-density circuit boards and fine circuit boards without using special equipment or jigs.

[0108] As described above, preferred embodiments of the present invention have been explained, but those skilled in the art will readily anticipate various changes and modifications within the obvious scope by reviewing this specification. Therefore, such changes and modifications will be interpreted as falling within the scope of the invention as defined by the claims.

[0109] 1. Thermoplastic liquid crystal polymer film 2. Metal layer (copper foil) 3. Laminate 4. SUS plate 5. Cushioning material 6. Laminate with circuit processing

Claims

1. A film composed of a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as thermoplastic liquid crystal polymer), wherein, when the apparent melting point of the thermoplastic liquid crystal polymer film is Tm (°C), a rubbery flat region exists in the temperature range of 240°C to Tm°C in the storage modulus profile obtained by dynamic viscoelasticity measurement, and the storage modulus E' at 280°C is... 280 A thermoplastic liquid crystal polymer film having a pressure of less than 60 MPa.

2. Storage modulus E' at 280°C 280 The thermoplastic liquid crystal polymer film according to claim 1, wherein the pressure is 30 MPa or more.

3. The thermoplastic liquid crystal polymer film according to claim 1, wherein the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer is 300°C or higher.

4. The thermoplastic liquid crystal polymer film according to claim 1, wherein the storage modulus E' of the rubbery flat region is 10 MPa or more and less than 80 MPa.

5. The thermoplastic liquid crystal polymer film according to claim 1, wherein the difference (Tm - Tm0) between the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film and the intrinsic melting point Tm0 (°C) of the thermoplastic liquid crystal polymer is -10 to +30°C.

6. The thermoplastic liquid crystal polymer film according to claim 1, wherein the endpoint temperature of the rubbery flat region is 280°C or higher.

7. A laminate comprising at least one layer of a thermoplastic liquid crystal polymer film according to any one of claims 1 to 6.

8. The laminate according to claim 7, further comprising at least one metal layer.

9. The laminate according to claim 8, wherein the metal layer comprises at least one metal selected from the group consisting of copper, aluminum, nickel, iron, and silver.

10. A molded article comprising a thermoplastic liquid crystal polymer film according to any one of claims 1 to 6.

11. The molded body according to claim 10, which is a circuit board.

12. A method for producing a thermoplastic liquid crystal polymer film according to any one of claims 1 to 6, comprising: a heat treatment step of heat-treating a pre-heat-resistant film containing a thermoplastic liquid crystal polymer for a period of 10 minutes to less than 60 minutes at a temperature of (Tm0-35)°C or higher and (Tm0-10)°C or lower, with a pressure of 1.0 MPa or higher, where Tm0 (°C) is the intrinsic melting point of the thermoplastic liquid crystal polymer; and a cooling step of cooling from the said temperature to 250°C at an average cooling rate of 20°C / min or less.

13. A method for manufacturing a laminate according to claim 8, comprising: a heat treatment step in which a metal layer is brought into contact with at least one surface of a pre-heat-resistant film containing a thermoplastic liquid crystal polymer, and the heat treatment is performed for a period of 10 minutes or more and less than 60 minutes at a temperature of (Tm0-35)°C or higher and (Tm0-10)°C or lower while applying a pressure of 1.0 MPa or higher, with the intrinsic melting point of the thermoplastic liquid crystal polymer being Tm0 (°C); and a cooling step in which the film is cooled from the said temperature to 250°C at an average cooling rate of 20°C / min or less.

14. A method for manufacturing a laminate comprising at least one layer of thermoplastic liquid crystal polymer film and at least one layer of metal, wherein the metal layer is bonded directly to at least one surface of the thermoplastic liquid crystal polymer film according to any one of claims 1 to 6, or via an adhesive layer.

Images