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

Abstract

The present invention provides a thermoplastic liquid crystal polymer film which can suppress resin flow during multilayering and exhibits excellent solder reflow resistance. The thermoplastic liquid crystal polymer film is a film composed of a thermoplastic polymer capable of forming an optically anisotropic molten phase, in which the heat of fusion ΔH at the apparent melting point Tm (℃) of the thermoplastic liquid crystal polymer film determined by differential scanning calorimetry is 2.30 J / g or more.

Description

Thermoplastic Liquid Crystal Polymer Film, Laminate, and Their Manufacturing Methods, and Molded Body Related Application

[0001] This application claims the priority of Japanese Patent Application No. 2024-221039 filed on December 17, 2024, and the entire content thereof is incorporated herein by reference and made 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 including at least one layer of the thermoplastic liquid crystal polymer film, and a molded body including the thermoplastic liquid crystal polymer film.

[0003] In recent years, due to the demand for miniaturization and weight reduction of devices in the fields of electronics, electrical, and communication industries, the need for higher density of printed wiring boards has been increasing. Along with this, various measures such as multi-layerization of wiring boards, narrowing of wiring pitches, and miniaturization of via holes have been advanced. For example, a high-density circuit is manufactured by multi-layerizing a metal-clad laminate composed of a non-metal layer and a metal layer through the non-metal layer. Conventionally, printed wiring boards and circuits have mainly used thermosetting resins such as phenolic resins and epoxy resins as the non-metal layer and laminated them with metal layers such as copper foils. However, it is known that thermosetting resins require time until proper lamination becomes possible due to a heating reaction.

[0004] On the other hand, for the purpose of improving productivity, simultaneous lamination of multiple sheets and simultaneous multi-stage manufacturing by equipment are generally adopted. Under such circumstances, the thermoplastic liquid crystal polymer material can be expected to have an effect of improving productivity by taking advantage of being a thermoplastic resin, and also attracts high attention as a representative of high-frequency transmission applications due to its extremely low water absorption rate and dielectric loss compared to other materials in terms of physical properties.

[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 / 218141) proposes a thermoplastic liquid crystal polymer film in which the apparent melting point of the thermoplastic liquid crystal polymer portion, the intrinsic melting point of the thermoplastic liquid crystal polymer portion, and the melting point rise rate of the thermoplastic liquid crystal polymer portion, all measured using a differential scanning calorimeter, have a specific relationship.

[0007] Patent document 2 (International Publication No. 2022 / 138618) proposes a liquid crystal polymer film in which the area of ​​the melting peak measured by differential scanning calorimetry is within a specific range.

[0008] Patent Document 3 (International Publication No. 2024 / 024653) describes studies on improving the reflow resistance of styrene resin substrates by using glass fibers and crystal nucleating materials. The crystal nucleating materials are thought to be used to raise the crystallization temperature and simultaneously improve the degree of crystallinity.

[0009] International Publication No. 2020 / 218141, International Publication No. 2022 / 138618, International Publication No. 2024 / 024653

[0010] Patent Document 1 describes a thermoplastic liquid crystal polymer film that can suppress resin flow during multilayering by thermocompression bonding and has a wide process window. However, in recent years, the demand for lead-free solder has increased, and reflow processing is now performed at higher temperatures than before, so there is room for further improvement in solder reflow resistance.

[0011] Furthermore, in the liquid crystal polymer film with a melting peak area range obtained in the example of Patent Document 2, the suppression of resin flow (lamination flow) during multilayering is insufficient. In addition, with liquid crystal polymer films having such characteristics, there is a risk that the connection circuit will sink into the substrate when soldering by crimping.

[0012] Patent Document 3 describes the low heat resistance of styrene-based resin substrates, and the addition of fillers such as glass fibers presents challenges such as reduced processability and the original properties of the resin.

[0013] The present invention aims to provide a thermoplastic liquid crystal polymer film that has a wide process window when multilayered and excellent solder reflow resistance, and a method for manufacturing the same. Furthermore, the invention 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.

[0014] The inventors of the present invention, after diligent research to achieve the above objectives, have surprisingly discovered that a thermoplastic liquid crystal polymer film in which the heat of fusion at the apparent melting point is within a specific range can sufficiently suppress the lamination flow in multilayering and exhibits excellent solder reflow resistance of the substrate, thus completing the present invention.

[0015] In other words, the present invention may be configured in the following embodiments. [Embodiment 1] A thermoplastic liquid crystal polymer film comprising a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), wherein the heat of fusion ΔH at the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film is 2.30 J / g or more (preferably 2.40 to 3.60 J / g, more preferably 2.50 to 3.40 J / g, and even more preferably 2.60 to 3.30 J / g). [Embodiment 2] The thermoplastic liquid crystal polymer film according to Embodiment 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 (preferably -8 to +25°C, more preferably -5 to +20°C). [Aspect 3] A thermoplastic liquid crystal polymer film according to aspect 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). [Aspect 4] A laminate comprising at least one layer of the thermoplastic liquid crystal polymer film according to any one aspect of aspects 1 to 3. [Aspect 5] The laminate according to aspect 4, further comprising at least one metal layer. [Aspect 6] The laminate according to aspect 5, wherein the metal layer comprises at least one metal selected from the group consisting of copper, aluminum, nickel, iron, and silver. [Aspect 7] A molded article comprising the thermoplastic liquid crystal polymer film according to any one aspect of aspects 1 to 3. [Aspect 8] The molded article according to aspect 7, which is a circuit board. [Aspect 9] A method for producing a thermoplastic liquid crystal polymer film according to any one of aspects 1 to 3, 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; and a cooling step of cooling from that 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 10] A method for producing a thermoplastic liquid crystal polymer film according to Aspect 9, wherein the heat treatment is performed for a time of 10 minutes or more but less than 60 minutes (preferably 10 minutes or more but 55 minutes or less, more preferably 15 minutes or more but 45 minutes or less, and even more preferably 20 minutes or more but 40 minutes or less). [Aspect 11] A method for producing a laminate according to Aspect 5 or 6, comprising: a heat treatment step of heat treatment at a temperature of (Tm0-35)°C or more and (Tm0-10)°C or less (preferably (Tm0-30)°C or more and (Tm0-15)°C or less), where Tm0 (°C) is the intrinsic melting point of the thermoplastic liquid crystal polymer, with a metal layer in contact with at least one surface of a pre-heat-resistant film containing a thermoplastic liquid crystal polymer; and a cooling step of cooling at an average cooling rate of 20°C / min or less (preferably 15°C / min or less, more preferably 10°C / min or less) from the said temperature to 250°C. [Aspect 12] The method for manufacturing a laminate according to aspect 11, wherein the heat treatment is performed for a period of 10 minutes or more but less than 60 minutes (preferably 10 minutes or more but 55 minutes or less, more preferably 15 minutes or more but 45 minutes or less, and even more preferably 20 minutes or more but 40 minutes or less). [Aspect 13] The method for manufacturing a laminate according to aspect 5 or 6, wherein a metal layer is bonded to at least one surface of a thermoplastic liquid crystal polymer film according to any one aspect of aspects 1 to 3, either directly or via an adhesive layer.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] The thermoplastic liquid crystal polymer film of the present invention can sufficiently suppress the lamination flow in multilayering and has excellent solder reflow resistance. Therefore, it can simplify the multilayer lamination process, such as that for high-density 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 without using special equipment or jigs.

[0020] 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 production of a multilayer laminate according to one aspect of the present invention.

[0021] [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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] (1) Aromatic or aliphatic diols (see Table 1 for representative examples)

[0026] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples)

[0027] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples)

[0028] (4) Aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids (see Table 4 for representative examples)

[0029] 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.

[0030]

[0031]

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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).

[0036] 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.

[0037] Furthermore, the aromatic diol (D) may be 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 which 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.

[0038] Further, the molar ratio of the repeating structural unit derived from an aromatic diol to the repeating structural unit derived from an 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.

[0039] The intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer is, for example, preferably 300°C or higher, more preferably in the range of 300 to 380°C, still 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 a 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.

[0040] 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 may have a melt viscosity of 30 to 100 Pa·s.

[0041] 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 to the thermoplastic liquid crystal polymer within a range that does not impair the effects of the present invention. Further, 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 composed of a thermoplastic liquid crystal polymer composition containing a thermoplastic liquid crystal polymer as a main component and at least one of these sub-components such as different polymers, additives, fillers, etc.

[0042] 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.

[0043] [Method for producing thermoplastic liquid crystal polymer film, laminate or molded body] The thermoplastic liquid crystal polymer film of the present invention is heat-treated at a temperature of (Tm0 - 35) °C or more and (Tm0 - 10) °C or less with respect to the thermoplastic liquid crystal polymer film (film before heat resistance improvement) composed of the thermoplastic liquid crystal polymer, and cooled at an average cooling rate of 20 °C / min or less from that temperature to 250 °C, whereby it can be produced.

[0044] The thermoplastic liquid crystal polymer film (film before heat resistance improvement) may be a cast film of the above thermoplastic liquid crystal polymer or thermoplastic liquid crystal polymer composition, or may be a film obtained by extrusion molding a melt-kneaded product of the thermoplastic liquid crystal polymer or thermoplastic liquid crystal polymer composition. At this time, any extrusion molding method can be used, but well-known T-die film forming and stretching methods, laminate stretching methods, inflation methods, etc. are industrially advantageous. In particular, in the inflation method, stress is applied not only in the machine axis direction (hereinafter abbreviated as MD) of the thermoplastic liquid crystal polymer film but also in the direction orthogonal thereto (hereinafter abbreviated as TD), and since it can be uniformly stretched in MD and TD, a thermoplastic liquid crystal polymer film (film before heat resistance improvement) with controlled molecular orientation, dielectric properties, etc. in MD and TD can be obtained.

[0045] Further, the thermoplastic liquid crystal polymer film (film before heat resistance improvement) may be stretched as necessary after extrusion molding. The stretching method itself is known, and either biaxial stretching or uniaxial stretching may be employed, but biaxial stretching is preferred because it is easier to control the molecular orientation degree. Also, for stretching, known uniaxial stretching machines, simultaneous biaxial stretching machines, sequential biaxial stretching machines, etc. can be used.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The thermoplastic liquid crystal polymer film (film before heat treatment) obtained in this manner is subjected to heat treatment to make it heat resistant. From the viewpoint of adjusting it to exhibit a specific heat of fusion, 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 at a temperature of (Tm0 - 35)°C or higher and (Tm0 - 10)°C or lower, 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 this heat treatment can increase the number of crystals near a specific melting point, and as a result, the heat of fusion (ΔH) can be increased.

[0050] From the viewpoint of increasing the heat of fusion at the apparent melting point Tm, the heat treatment temperature is preferably (Tm0-35)°C or higher and (Tm0-10)°C or lower, and more preferably (Tm0-30)°C or higher and (Tm0-15)°C or lower. For example, the heat treatment temperature may be within the above range, as well as 260 to 350°C (preferably 270 to 340°C, more preferably 280 to 330°C).

[0051] The heat treatment time varies depending on the heat treatment temperature, but from the viewpoint of increasing the heat of fusion at the apparent melting point Tm, it is preferably 10 minutes or more and less than 60 minutes, more preferably 10 minutes or more and 55 minutes or less, even more preferably 15 minutes or more and 45 minutes or less, and even more preferably 20 minutes or more and 40 minutes or less.

[0052] It is preferable to slow down 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.

[0053] For heat treatment, known or conventional heat sources can be used. Preferred heat sources include, for example, hot air ovens, steam ovens, electric heaters, infrared heaters, ceramic heaters, hot rolls, hot presses, and electromagnetic irradiation machines (e.g., microwave irradiation machines). These heat sources may be used individually or in combination of two or more.

[0054] Heat treatment for heat resistance can be performed in one or more 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. In a one-stage heat treatment, heat resistance is achieved by the first heat treatment alone, and in a multi-stage heat treatment, after the first heat treatment, the heat treatment temperature of the next stage 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.

[0055] The heat treatment method is not particularly limited as long as the heat-resistant thermoplastic liquid crystal polymer film has a specific heat of fusion. For example, the thermoplastic liquid crystal polymer film (film before heat treatment) may be directly heat-treated by roll-to-roll or the like, the thermoplastic liquid crystal polymer film (film before heat treatment) may be laminated with a substrate and heat-treated together, 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 in the state in which it is 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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).

[0062] 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.

[0063] 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.

[0064] 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 at a temperature of (Tm0-35)°C to (Tm0-10)°C with the metal layer in contact with at least one surface of the film before heat treatment, and then cooling it 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. For example, the heat treatment time is preferably 10 minutes or more and less than 60 minutes.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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 a heat of fusion within a specific range of apparent melting points, as described later.

[0071] [Thermoplastic liquid crystal polymer film, laminate and molded article] The thermoplastic liquid crystal polymer film of the present invention has a heat of fusion ΔH of 2.30 J / g or more at the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film.

[0072] The thermoplastic liquid crystal polymer film of the present invention has a melting heat ΔH within the above range, which allows for control of resin fluidity and suppresses indentation in the thickness direction of the resin during the soldering process, resulting in a tendency for excellent solder reflow resistance. Furthermore, during the manufacturing of multilayer laminates, the flow of resin in the planar direction perpendicular to the thickness direction can be suppressed, which is considered to sufficiently suppress the lamination flow in multilayer construction.

[0073] The thermoplastic liquid crystal polymer film of the present invention preferably has a heat of fusion ΔH at its apparent melting point Tm of 2.40 J / g or more, more preferably 2.50 J / g or more, and even more preferably 2.60 J / g or more. Furthermore, the heat of fusion ΔH is preferably 3.60 J / g or less, more preferably 3.40 J / g or less, and even more preferably 3.30 J / g or less.

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

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

[0088] (Apparent melting point Tm and heat of fusion ΔH of thermoplastic liquid crystal polymer film) Using a differential scanning calorimeter (Shimadzu Corporation), a sample of a predetermined size was taken from the thermoplastic liquid crystal polymer film after heat treatment obtained in the examples and comparative examples, placed in a sample container, and 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 defined as the apparent melting point Tm of the thermoplastic liquid crystal polymer film. In addition, the area of ​​the endothermic peak enclosed by the endothermic peak and baseline of the DSC curve was calculated to determine the heat of fusion ΔH (unit: J / g) of the sample. The endothermic peak and baseline in the DSC curve were identified based on JIS K 7121:2012.

[0089] (Intrinsic melting point Tm0 of thermoplastic liquid crystal polymer) Using a differential scanning calorimeter (manufactured by Shimadzu Corporation), a sample of a predetermined size was taken from the thermoplastic liquid crystal polymer film after heat treatment obtained in the examples and comparative examples, placed in a sample container, heated from room temperature to 400°C at a rate of 10°C / min, cooled to room temperature at a rate of 10°C / min, and then heated again from room temperature to 400°C at a rate of 10°C / min. The position of the endothermic peak that appeared at this time was defined as the intrinsic melting point Tm0 of the thermoplastic liquid crystal polymer constituting the thermoplastic liquid crystal polymer film.

[0090] (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.

[0091] (Hot bar test) A hot bar test was performed using a flip-chip bonder M1300 (manufactured by Hisol Co., Ltd.) to evaluate solder reflow resistance. A 15 mm x 15 mm sample was cut from the heat-treated thermoplastic liquid crystal polymer film obtained in the examples and comparative examples, and a circuit was created with L / S (Line and Space) = 1 mm / 2 mm. This circuit was placed on a stage at 25°C, and a 12 mm x 12 mm head temperature was set to 350°C, and pressure was applied to the circuit to a load of 0.1 MPa (contact area with the circuit: 12 mm x 1 mm x 4), and the pressure was maintained for 20 seconds. The sinking of the circuit portion into the resin (thermoplastic liquid crystal polymer film) was measured by cross-sectional observation of the sample, and evaluated according to the following criteria. A: The indentation is 1 / 3 or less of the circuit thickness of 12 μm. B: The indentation is greater than 1 / 3 but 1 / 2 or less of the circuit thickness of 12 μm. C: The indentation is greater than 1 / 2 of the circuit thickness of 12 μm.

[0092] <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 280-340°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 with a thickness of 50 μm.

[0093] 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 a 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.

[0094] <Example 1> The laminate obtained in Manufacturing Example 1 was heat-treated at 310°C for 30 minutes, and then cooled by adjusting the average cooling rate from 310°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 the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0095] <Example 2> The laminate obtained in Manufacturing Example 1 was heat-treated at 310°C for 45 minutes, and then cooled by adjusting the average cooling rate from 310°C to 250°C to 15°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 the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0096] <Example 3> The laminate obtained in Manufacturing Example 1 was heat-treated at 300°C for 30 minutes, and then cooled by adjusting the average cooling rate from 300°C to 250°C to 15°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 the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0097] <Example 4> The laminate obtained in Manufacturing Example 1 was heat-treated at 300°C for 45 minutes, and then cooled by adjusting the average cooling rate from 300°C to 250°C to 10°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 the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0098] <Comparative Example 1> The laminate obtained in Manufacturing Example 1 was evaluated without heat treatment. The copper foil was removed from the laminate by etching, and the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0099] <Comparative Example 2> The laminate obtained in Manufacturing Example 1 was heat-treated at 320°C for 30 minutes, and then cooled by adjusting the average cooling rate from 320°C to 250°C to 30°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 the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0100] <Comparative Example 3> The laminate obtained in Manufacturing Example 1 was heat-treated at 290°C for 30 minutes, and then cooled by adjusting the average cooling rate from 290°C to 250°C to 10°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 the various melting points and heat of fusion ΔH of the thermoplastic liquid crystal polymer film were measured. In addition, the hot bar and lamination flow of the obtained laminate were evaluated. The results are shown in Table 7.

[0101]

[0102] As shown in Table 7, Examples 1 to 4, in which the heat of fusion ΔH at the apparent melting point Tm is within a specific range, showed good solder reflow resistance in the hot bar test and also good heat resistance in the multilayer flow test. In contrast, Comparative Examples 1 to 3, in which the heat of fusion ΔH at the apparent melting point Tm is not within a specific range, showed poor solder reflow resistance in the hot bar test and poor heat resistance in the multilayer flow test.

[0103] The thermoplastic liquid crystal polymer film of the present invention allows for control of resin fluidity by increasing the number of crystals near a specific melting point and increasing the enthalpy of melting. This suppresses indentations in the thickness direction of the resin during the soldering process and lateral flow of the resin during the manufacturing of multilayer laminates. For example, this leads to the simplification of the multilayer lamination process for high-density circuits, which has been complicated until now, and enables the low-cost manufacturing of laminates. Furthermore, it becomes possible to manufacture multilayer laminated substrates for high-density circuits without using special equipment or jigs.

[0104] 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.

[0105] 1. Thermoplastic liquid crystal polymer film 2. Metal layer (copper foil) 3. Laminate 4. SUS plate 5. Cushioning material

Claims

1. A thermoplastic liquid crystal polymer film comprising a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), wherein the heat of fusion ΔH at the apparent melting point Tm (°C) of the thermoplastic liquid crystal polymer film is 2.30 J / g or more.

2. 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.

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. A laminate comprising at least one layer of a thermoplastic liquid crystal polymer film according to any one of claims 1 to 3.

5. The laminate according to claim 4, further comprising at least one metal layer.

6. The laminate according to claim 5, wherein the metal layer comprises at least one metal selected from the group consisting of copper, aluminum, nickel, iron, and silver.

7. A molded article comprising a thermoplastic liquid crystal polymer film according to any one of claims 1 to 3.

8. The molded body according to claim 7, which is a circuit board.

9. A method for producing a thermoplastic liquid crystal polymer film according to any one of claims 1 to 3, 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, where Tm0 (°C) is the intrinsic melting point of the thermoplastic liquid crystal polymer; and a cooling step of cooling from said temperature to 250°C at an average cooling rate of 20°C / min or less.

10. The method for producing a thermoplastic liquid crystal polymer film according to claim 9, wherein the heat treatment is performed for a period of 10 minutes or more but less than 60 minutes.

11. A method for manufacturing a laminate according to claim 5, comprising: a heat treatment step of heat treatment at a temperature of (Tm0-35)°C or higher and (Tm0-10)°C or lower, where Tm0 (°C) is the intrinsic melting point of the thermoplastic liquid crystal polymer, with a metal layer in contact with at least one surface of a pre-heat-resistant film containing a 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.

12. The method for manufacturing a laminate according to claim 11, wherein the heat treatment is performed for a period of 10 minutes or more but less than 60 minutes.

13. 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 3, or via an adhesive layer.

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