Thermoplastic liquid crystal polymer molded articles, metal-clad laminates, and circuit boards

Abstract

In order to improve overall light transmittance while maintaining the high haze value of a thermoplastic liquid crystal polymer, provided is a thermoplastic liquid crystal polymer molded body that has a haze value of 99% or higher and a thermal expansion coefficient of 16-27 ppm / °C, the correlation of the light absorption coefficient (ε) and the thickness (x) satisfying ε≤0.21x-0.55. The thermoplastic liquid crystal polymer may be a polyester containing repeating units derived from a substance selected from the group consisting of: p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; 6-hydroxy-2-naphthoic acid, terephthalic acid, or p-aminophenol; p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and terephthalic acid; 6-hydroxy-2-naphthoic acid, terephthalic acid, p-aminophenol, isophthalic acid, hydroquinone, and naphthalene dicarboxylic acid; or p-hydroxybenzoic acid, terephthalic acid, and 4,4'-dihydroxybiphenyl.

Description

Related Application

[0001] This application claims the priority of Japanese Patent Application No. 2020-105862 filed on June 19, 2020, the entire disclosure of which is incorporated herein by reference in its entirety.

Technical Field

[0002] The present invention relates to a thermoplastic liquid crystal polymer molded body having high total light transmittance and an ultra-high haze value, a metal-clad laminate using this molded body as a base material, and a circuit board.

Background Art

[0003] Due to the properties of thermoplastic liquid crystal polymers, thermoplastic liquid crystal polymer molded bodies have low dielectric properties (low dielectric constant and low dielectric tangent), and thus are attracting attention in applications that require dielectric properties.

[0004] For example, in recent years, as the transmission signals in printed wiring boards have become faster, the frequency of signals has been increasing. Along with this, the base materials used in printed wiring boards are required to have excellent low dielectric properties in the high-frequency range. In response to such requirements, thermoplastic liquid crystal polymer films having low dielectric properties have attracted attention as base films used in printed wiring boards, replacing conventional polyimide (PI) and polyethylene terephthalate films.

[0005] In addition, thermoplastic liquid crystal polymers have high light diffusion properties (high haze value) due to a collection of structures called microdomains. Therefore, the above-mentioned thermoplastic liquid crystal polymer molded bodies are also expected to be applied to electronic and optical materials such as displays, lighting fixtures, polarizer protection, and anti-glare applications.

[0006] However, due to their low transparency, thermoplastic liquid crystal polymer molded bodies are mostly treated as internal parts that are not visible to the human eye in devices, and have the problem that the freedom in device design and designability are limited.

[0007] Furthermore, with the increasing demand for multilayer circuit boards capable of accommodating multiple circuit connections, there is a need for technology to suppress misalignment of interlayer connection circuit wiring when connecting each layer. However, thermoplastic liquid crystal polymer films have the problem of causing interlayer connection failures because their low transparency provides little information necessary for aligning interlayer connection circuit wiring.

[0008] For example, Patent Document 1 (Japanese Patent Publication No. 2005-178056) discloses a molding method for obtaining a transparent molded article with a haze value of 40% or less by holding a liquid crystalline polyester resin at a temperature of -20°C or higher from its melting point for 10 seconds or more, either during or after molding.

[0009] Techniques are also being considered to impart light diffusivity to the film while maintaining a certain degree of transparency. For example, Patent Document 2 (Japanese Patent Publication No. 2007-293316) describes a light diffusivity film in which 2 to 40 parts by mass of an incompatible light diffusive agent is compounded with a crystalline polyester on a support layer made of crystalline polyester.

[0010] On the other hand, Patent Document 3 (International Publication No. 2011 / 118449) discloses a thermoplastic liquid crystal polymer film with improved light reflectivity having 8 to 40 crystalline domains per 10 μm in the thickness direction of the film. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2005-178056 Public Relations [Patent Document 2] Japanese Patent Publication No. 2007-293316 [Patent Document 3] International Publication No. 2011 / 118449 [Overview of the project] [Problems that the invention aims to solve]

[0012] However, Patent Document 1 presents a problem in that while the transparency of the film is improved, it simultaneously causes a decrease in the haze value and a reduction in light diffusion. For example, when using a film as a circuit board material, it is desirable to have a certain degree of transparency in order to ensure design flexibility and ease of processing, but when the circuit board is incorporated into the final product, it is desirable for the film to have a certain degree of light diffusion in order to maintain the confidentiality of the circuit design.

[0013] Patent Document 2 describes how light diffusion is achieved by filling the base material with particles that are incompatible with it, assuming applications such as backlight units for liquid crystal displays. However, when manufacturing multilayer circuit boards using layers containing such dissimilar materials, uneven removal of smear generated during the drilling process (e.g., laser or drill) for conductive processing of interlayer connections is likely to occur, leading to problems such as poor plating on the subsequent hole walls. Therefore, managing inorganic particles and insulating resin materials with different processing characteristics becomes complex, and from the standpoint of increased costs, it is industrially disadvantageous compared to the present invention.

[0014] Patent Document 3 describes how increasing the number of crystalline domains in the thickness direction can improve light reflectivity, but in that case, the light transmittance of the film is inhibited.

[0015] Therefore, the object of the present invention is to provide a thermoplastic liquid crystal polymer molded article having high total light transmittance and ultra-high haze value, as well as a metal-clad laminate and circuit board using the same. [Means for solving the problem]

[0016] Typically, liquid crystalline polyester resins consist of a collection of structures called microdomains (a type of higher-order structure). Because voids and defects may exist between microdomains, and because the optical anisotropy between microdomains is not continuous, light is strongly reflected at the interfaces between microdomains. Due to this structure, it has been considered difficult to make liquid crystalline polyester resins transparent.

[0017] As a result of intensive studies to achieve the above object, the inventors of the present invention have found that by controlling the size of the microdomains and the interface between the microdomains, it is possible to improve the light transmittance while maintaining an extremely high haze value.

[0018] Furthermore, it has been found that a thermoplastic liquid crystal polymer molded body having such a controlled higher-order structure has strong adhesion strength to an adherent and excellent heat resistance when used in a multilayer structure.

[0019] That is, the present invention provides the following preferred forms.

[0020] A first configuration of the present invention is a thermoplastic liquid crystal polymer molded body having a haze value of 99% or more, having a coefficient of thermal expansion of 16 to 27 ppm / °C, the correlation between the absorption coefficient (ε) and the thickness (x) is ε≦0.21x -0.55 and satisfying the above, a thermoplastic liquid crystal polymer molded body.

[0021] The above thermoplastic liquid crystal polymer molded body may be such that the thermoplastic liquid crystal polymer is a polyester containing a repeating unit derived from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; a polyester containing a repeating unit derived from 6-hydroxy-2-naphthoic acid, terephthalic acid and p-aminophenol; a polyester containing a repeating unit derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid and terephthalic acid; a polyester containing a repeating unit derived from 6-hydroxy-2-naphthoic acid, terephthalic acid, p-aminophenol, isophthalic acid, hydroquinone and naphthalenedicarboxylic acid; and a polyester containing a repeating unit derived from p-hydroxybenzoic acid, terephthalic acid and 4,4'-dihydroxybiphenyl, and is selected from the group consisting of.

[0022] The above thermoplastic liquid crystal polymer molded body may have a film-like shape.

[0023] The second configuration of the present invention is a metal-clad laminate, comprising the film-like thermoplastic liquid crystal polymer molded body, and a metal layer joined to at least one surface (one-sided or both-sided) of the molded body, and is a laminate.

[0024] The third configuration of the present invention is a circuit board, including the above metal-clad laminate, wherein the at least one metal layer has a circuit pattern, and is a circuit board. The circuit board may be a multilayer circuit board including at least one layer of the above metal-clad laminate.

[0025] In addition, any combination of at least two components disclosed in the claims and / or the specification is included in the present invention. In particular, any combination of two or more of the claims described in the claims is included in the present invention.

Effects of the Invention

[0026] The thermoplastic liquid crystal polymer molded body of the present invention has both a high total light transmittance and an ultra-high haze value, and has a specific coefficient of thermal expansion. Therefore, for example, when multilayer laminating an electronic circuit board, due to the high total light transmittance, it is easy to align the circuit wirings between layers and suppress the positional deviation of the circuit wirings. At the same time, due to the ultra-high haze value, it is possible to add functions such as ensuring the concealment of the wirings and elements in the device and reducing light interference, and it is extremely useful as an insulator material. In addition, the degree of freedom in device design and the designability are increased, and applications to electronic and optical materials such as displays, optical sensors, anti-glare films, lighting fixtures, and polarizer protection films can be expected. Further, by controlling the microdomain size, the adhesion to the adherend is high and the heat resistance is also excellent, so it is extremely useful as an insulator material for electronic circuit boards and the like.

Brief Description of the Drawings

[0027] [Figure 1]This is a schematic cross-sectional view illustrating the manufacturing process of a molded body, a metal-clad laminate, and a circuit board according to one embodiment of the present invention. [Figure 2] This graph shows the correlation between film thickness and absorption coefficient of the examples and comparative examples. [Modes for carrying out the invention]

[0028] The molded body of the present invention , melt A molded article made of a liquid crystal polymer (hereinafter referred to as thermoplastic liquid crystal polymer) that exhibits optical anisotropy during melting, exhibits an extremely high haze value of 99% or more, and has a correlation between the absorption coefficient (ε) and thickness (x) of ε ≤ 0.21x -0.55 This is a molded body that satisfies the following conditions.

[0029] The shape of the molded body described above is not particularly limited, but for example, it may have a film-like shape (i.e., a thermoplastic liquid crystal polymer film). Furthermore, the present invention also includes laminates (metal-clad laminates) in which a metal layer is laminated on at least one surface (one or both) of the molded body, and circuit boards in which a conductive circuit is formed on at least one surface of the molded body.

[0030] (Thermoplastic liquid crystal polymer) The thermoplastic liquid crystal polymer used in the present invention is a polymer capable of forming an optically anisotropic molten phase. Examples of thermoplastic liquid crystal polymers include thermoplastic liquid crystal polyesters, or thermoplastic liquid crystal polyesteramides in which amide bonds are introduced.

[0031] 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.

[0032] 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.

[0033] (1) Aromatic or aliphatic diols (see Table 1 for representative examples) [Table 1]

[0034] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples) [Table 2]

[0035] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples) [Table 3]

[0036] (4) Aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids (see Table 4 for representative examples) [Table 4]

[0037] Typical examples of thermoplastic liquid crystal polymers obtained from these raw material compounds include copolymers having the structural units shown in Tables 5 and 6.

[0038] [Table 5] [Table 6]

[0039] Of these copolymers, polymers 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.

[0040] When the thermoplastic liquid crystal polymer is a copolymer containing repeating units of p-hydroxybenzoic acid (A) and 6-hydroxy-2-naphthoic acid (B), the molar ratio (A) / (B) is preferably (A) / (B) = 10 / 90 to 90 / 10, more preferably 50 / 50 to 90 / 10, even more preferably 75 / 25 to 90 / 10, even more preferably 75 / 25 to 85 / 15, and particularly preferably 77 / 23 to 80 / 20.

[0041] 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.

[0042] 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 diol selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid The molar ratio of each repeating unit of von acid (E) 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).

[0043] 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.

[0044] 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.

[0045] Furthermore, the molar ratio of repeating structural units derived from aromatic diol (D) to repeating structural units derived from aromatic dicarboxylic acid (E) is preferably (D) / (E) = 95 / 100 to 100 / 95. If the ratio deviates from this range, the degree of polymerization does not increase and the mechanical strength tends to decrease.

[0046] In the thermoplastic liquid crystal polymer described above, it is particularly preferable to use a thermoplastic liquid crystal polymer selected from the group consisting of: a polyester containing repeating units derived from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; a polyester containing repeating units derived from 6-hydroxy-2-naphthoic acid, terephthalic acid, and p-aminophenol; a polyester containing repeating units derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and terephthalic acid; a polyester containing repeating units derived from 6-hydroxy-2-naphthoic acid, terephthalic acid, p-aminophenol, isophthalic acid, hydroquinone, and naphthalenedicarboxylic acid; and a polyester containing repeating units derived from p-hydroxybenzoic acid, terephthalic acid, and 4,4'-dihydroxybiphenyl.

[0047] Furthermore, the ability to form an optically anisotropic molten phase as referred to in this invention 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.

[0048] Preferred thermoplastic liquid crystal polymers have a melting point (hereinafter referred to as Tm0) in the range of, for example, 200 to 360°C, more preferably in the range of 240 to 350°C, even more preferably Tm0 is 260 to 330°C, and still more preferably Tm0 is 290 to 330°C. The melting point can be obtained by observing the thermal behavior of the thermoplastic liquid crystal polymer sample using a differential scanning calorimeter. Specifically, the thermoplastic liquid crystal polymer sample is heated at a rate of 10°C / min until completely melted, then the molten material is cooled to 50°C at a rate of 10°C / min, and the position of the endothermic peak that appears after heating again at a rate of 10°C / min is determined as the melting point of the thermoplastic liquid crystal polymer sample.

[0049] The thermoplastic liquid crystal polymer may contain thermoplastic polymers such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyether ether ketone, and fluororesin, as well as various additives and fillers, to the extent that the effects of the present invention are not impaired.

[0050] In the present invention, it is preferable that the thermoplastic liquid crystal polymer used does not contain additives or fillers. By not containing dissimilar materials, unevenness in smear removal during the drilling process (e.g., laser or drill) for conductive processing for interlayer connection is less likely to occur, and subsequent plating defects on the hole walls are less likely to occur. For this reason, the thermoplastic liquid crystal polymer molded article used in the present invention is preferably a thermoplastic liquid crystal polymer film that does not contain additives or fillers.

[0051] (Molded body) The shape of the molded article of the present invention is not limited, and the above-mentioned thermoplastic liquid crystal polymer may be processed into any shape depending on the application, but for example, it may have a film-like shape. A film-like thermoplastic liquid crystal polymer, so-called thermoplastic liquid crystal polymer film, can be obtained, for example, by extruding a molten kneaded mixture of the above-mentioned thermoplastic liquid crystal polymer. Any method can be used as the extrusion molding method, but the well-known T-die method and inflation method are industrially advantageous. In particular, in the inflation method, stress is applied not only in the machine axis direction (hereinafter abbreviated as MD direction) of the thermoplastic liquid crystal polymer film but also in the direction perpendicular to it (hereinafter abbreviated as TD direction), and since it can be stretched uniformly in the MD direction and TD direction, a thermoplastic liquid crystal polymer film with controlled molecular orientation, dielectric properties, etc. in the MD direction and TD direction can be obtained.

[0052] For example, in extrusion molding using the T-die method, the molten sheet extruded from the T-die may be stretched simultaneously in both the MD direction and the TD direction to form a thermoplastic liquid crystal polymer film, or the molten sheet extruded from the T-die may be stretched first in the MD direction and then in the TD direction to form a film.

[0053] Furthermore, in extrusion molding by the inflation method, a cylindrical sheet extruded from a ring die may be stretched at a predetermined draw ratio (corresponding to the stretching ratio in the MD direction) and blow ratio (corresponding to the stretching ratio in the TD direction) to form a film.

[0054] The stretch ratio in this type of extrusion molding may be, for example, about 1.0 to 10 as the stretch ratio (or draw ratio) in the MD direction, preferably about 1.2 to 7, and more preferably about 1.3 to 7. The stretch ratio (or blow ratio) in the TD direction may also be, for example, about 1.5 to 20, preferably about 2 to 15, and more preferably about 2.5 to 14.

[0055] Furthermore, known or conventional heat treatments may be performed as needed to adjust the melting point and / or thermal expansion coefficient of the thermoplastic liquid crystal polymer film. The heat treatment conditions can be set appropriately according to the purpose. For example, the melting point (Tm) of the thermoplastic liquid crystal polymer film may be increased by heating it for several hours at a temperature of (Tm0-10)°C or higher (for example, around (Tm0-10) to (Tm0+30)°C, preferably around (Tm0) to (Tm0+20)°C) relative to the melting point (Tm0) of the thermoplastic liquid crystal polymer.

[0056] The melting point (Tm) of the thermoplastic liquid crystal polymer film may be, for example, 270 to 380°C, preferably in the range of 280 to 370°C, and more preferably in the range of 290 to 360°C. The 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 at a rate of 10°C / min can be determined as the melting point (Tm) of the thermoplastic liquid crystal polymer film.

[0057] 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 multilayer circuit board, it may be 10 to 500 μm, preferably 15 to 250 μm, more preferably 25 to 180 μm, or for example, 25 to 100 μm.

[0058] The thermoplastic liquid crystal polymer molded article of the present invention has a coefficient of thermal expansion in the planar direction of the molded article adjusted to 16 to 27 ppm / °C, preferably 17 ppm / °C or higher, more preferably 18 ppm / °C or higher. Furthermore, it is preferably 25 ppm / °C or lower, more preferably 23 ppm / °C or lower, and even more preferably 20 ppm / °C or lower. The coefficient of thermal expansion can be measured, for example, by the TMA method.

[0059] While the thermoplastic liquid crystal polymers described above generally exhibit high haze values, the present invention improves total light transmittance compared to conventional products while maintaining a high haze value. Specifically, the thermoplastic liquid crystal polymer molded article (for example, a thermoplastic liquid crystal polymer film) of the present invention exhibits a haze value of 99% or higher, and the correlation between the absorption coefficient (ε) and thickness (x) is ε ≤ 0.21x. -0.55 It satisfies the following conditions.

[0060] The optical properties described above can be imparted to a molded article, for example, by first processing a thermoplastic liquid crystal polymer into a predetermined shape and then performing a predetermined heat treatment. The heat treatment is preferably performed at a temperature higher than the melting point Tm of the molded article (thermoplastic liquid crystal polymer film), for example, at a temperature 20°C or higher than the melting point Tm, or for example, at a temperature 20 to 40°C higher than the melting point Tm. The heat treatment time is preferably at least 1 second, and more preferably 4 seconds or more. On the other hand, if the heat treatment time is too long, the thermoplastic liquid crystal polymer will deteriorate, so the heat treatment time is preferably 500 seconds or less, and more preferably 400 seconds or less.

[0061] The reason why the above heat treatment can impart the desired optical properties is that, on the one hand, the thermoplastic liquid crystal polymer film retains its multi-domain structure, thus maintaining a haze value of 99% or higher; and on the other hand, transparency is improved due to the growth of domain size during heat treatment and the reduction of defects due to the relaxation of strain during molding. In the case of thermoplastic liquid crystal polymer films, the above heat treatment may be performed after forming a metal layer on one or both sides. After heat treatment, it may be used as a metal-clad laminate as described below, or the metal layer may be peeled off and used for other applications.

[0062] (Metal-clad laminate) The laminate of the present invention is a laminate (so-called metal-clad laminate) having the above-mentioned thermoplastic liquid crystal polymer molded body (e.g., thermoplastic liquid crystal polymer film) and a metal layer laminated on at least one side thereof. The laminate may be, for example, a single-sided or double-sided metal-clad laminate in which a metal layer is laminated on one or both sides of a thermoplastic liquid crystal polymer film.

[0063] The metal layer can be appropriately determined depending on the purpose, but copper, nickel, cobalt, aluminum, gold, tin, chromium, etc. are preferably used. The thickness of the metal layer may be 0.01 to 200 μm, preferably 0.1 to 100 μm, more preferably 1 to 80 μm, and particularly preferably 2 to 50 μm.

[0064] The method of laminating the metal layer is not particularly limited, but for example, using a roll press in a roll-to-roll manner, a thermoplastic liquid crystal polymer fill Mu A metal foil (e.g., copper foil) may be pressed onto the film, or it may be pressed using a double belt press, vacuum heat press, or the like. Alternatively, a metal layer may be vacuum deposited onto the surface of a thermoplastic liquid crystal polymer film, and then a metal layer may be formed on the deposited layer by electroplating.

[0065] (Circuit board) A circuit board according to one aspect of the present invention is formed using a metal-clad laminate with the thermoplastic liquid crystal polymer molded body of the present invention as a base material. In this circuit board, circuits are formed on one or both metal layers. The circuits can be formed by known subtractive, additive, or semi-additive methods. The thickness of the circuit (metal layer) may be, for example, 10 to 14 μm, and preferably 11 to 13 μm. The circuit board may consist of the above-mentioned metal-clad laminate, or it may be a laminated circuit board with other layers further laminated thereon.

[0066] Furthermore, the circuit board may have through-holes formed on it by various known or commonly used manufacturing methods, as needed. In that case, the circuit board may have a through-hole plating layer formed on it, and the thickness of the circuit (metal layer) with the through-hole plating layer formed on it may be, for example, 20 to 40 μm, and preferably 25 to 35 μm.

[0067] (Method for manufacturing a thermoplastic liquid crystal polymer molded article) Hereinafter, an example of the manufacturing process for a molded body, a metal-clad laminate, and a circuit board according to one embodiment of the present invention will be described with reference to Figure 1. Note that Figure 1 is a schematic cross-sectional view for illustrative purposes, and the thickness ratio, width, etc. of the material do not reflect the actual size. A. Preparation process First, prepare the thermoplastic liquid crystal polymer film 1 and the metal foil 2 that will form the metal layer. B.Lamination process Next, the thermoplastic liquid crystal polymer film 1 and the metal foil 2 are pressed together by thermocompression to form a laminated precursor 3. C. Heat treatment process Next, the laminate precursor 3 is heat-treated, preferably in an inert atmosphere such as nitrogen gas, at a temperature higher than the melting point of the thermoplastic liquid crystal polymer film 1 (for example, 20°C or higher than the melting point) to improve the total light transmittance of the thermoplastic liquid crystal polymer film 1, thereby forming a metal-clad laminate 30, which is the laminate of the present invention, in which the film-like thermoplastic liquid crystal polymer molded body 10 and the metal foil 2 are laminated. Furthermore, when heat treatment is performed continuously, the load and tension that stabilizes the laminate during continuous heat treatment may be set according to the thickness and width of the laminate precursor, but from the viewpoint of dimensional stability, it is preferable to perform the heat treatment without applying any load or tension to the laminate precursor 3 and while it is in a horizontal, stationary state. D.Circuit processing process Next, the metal foil 2 is processed to form a circuit board 40 having a circuit pattern 20.

[0068] The conditions for each of the above steps may be those described above. Furthermore, the metal foil 2 may be removed from the metal-clad laminate 30 after the heat treatment process by etching or the like, and the resulting film-like thermoplastic liquid crystal polymer molded body 10 may be used for other purposes. Also, in Figure 1, the metal foil 2 is pressed onto one side of the thermoplastic liquid crystal polymer film 1, but the metal foil 2 may be pressed onto both sides.

[0069] In the lamination process described in B. above, the metal foil 2 can be appropriately determined according to the purpose, but examples include metal foils such as copper, nickel, cobalt, aluminum, gold, tin, and chromium. It is preferable to use copper foil or aluminum foil, and more preferable to use copper foil.

[0070] In step C. Heat treatment described above, the heat treatment temperature is preferably Tm + 10°C or higher, more preferably Tm + 15°C or higher, and even more preferably Tm + 20°C or higher. It is also preferably Tm + 40°C or lower, more preferably Tm + 35°C or lower, and even more preferably Tm + 30°C or lower. The heat treatment time is preferably 1 second or more, more preferably 2 seconds or more, even more preferably 3 seconds or more, and even more preferably 4 seconds or more. It is also preferably 500 seconds or less, more preferably 400 seconds or less, even more preferably 350 seconds or less, and even more preferably 300 seconds or less. [Examples]

[0071] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way by these examples. The evaluation methods for thermoplastic liquid crystal polymer films used in the following examples and comparative examples are shown below.

[0072] (1) Film thickness The film thickness was measured using a digital thickness gauge (manufactured by Mitutoyo Corporation) at 1 cm intervals in the TD direction on the obtained film, and the average of 10 points was taken as the film thickness.

[0073] (2) Total light transmittance Total light transmittance was measured using a HAZEMETER, HM-150 (manufactured by Murakami Color Technology Research Institute Co., Ltd.) in accordance with JIS K7136.

[0074] (3) Hayes Haze was measured using a HAZEMETER, HM-150 (manufactured by Murakami Color Technology Laboratory Co., Ltd.) in accordance with JIS K7136.

[0075] (4) Absorption coefficient The absorption coefficient (ε) was calculated using the Lambert-Wehr formula, with the measured total light transmittance (R: 100R in percentage terms) and the film thickness (x), as ε = -logR / x.

[0076] (5) Coefficient of thermal expansion (CTE) of the film Using a thermomechanical analyzer (TMA), measurements were taken between 30°C and 150°C after heating from 25°C to 200°C at a rate of 5°C / min, cooling to 30°C at a rate of 20°C / min, and then heating again at a rate of 5°C / min. Measurements were taken in both the TD and MD directions of the film, and the average value was taken as the thermal expansion coefficient of the film.

[0077] (6) Dimensional change rate of copper-clad laminate Measurements were taken in accordance with IPC-TM-6502.2.4. The heating conditions were 150°C for 30 minutes, and the dimensional change rate (%) of the sample before and after heating was measured.

[0078] (7) Adhesion strength of copper-clad laminates In accordance with JIS C5016-1994, the peel strength of the copper foil of the copper-clad laminate was measured using a tensile testing machine (Nidec-Shimpo Corporation, Digital Force Gauge FGP-2) while peeling the copper foil at a speed of 50 mm per minute in a 90° direction, and the obtained value was defined as the adhesive strength. (8) Solder heat resistance Solder heat resistance was measured by examining the time it took for the film surface to maintain its original shape on a molten solder bath maintained at a predetermined temperature. Specifically, the laminate was placed on a 300°C solder bath for 60 seconds, and changes in the film surface, such as blistering and deformation, were visually observed. In Table 7, those that showed no blistering or deformation after 60 seconds were rated as "good," and those that showed blistering or deformation were rated as "poor." (9) Visibility Samples were placed on paper printed with a 0.1 mm wide striped pattern and circular and square patterns of varying sizes (diameter and side length 0.5-5 mm), and the minimum size of the patterns that could be identified was observed. The table shows the smallest size of the patterns that could be identified.

[0079] [Reference example] The raw material for the thermoplastic liquid crystal polymer molded article was a copolymer of 6-hydroxy-2-naphthoic acid and p-hydroxybenzoic acid. The thermoplastic liquid crystal polymer, which has a melting point of 310°C, was heated and kneaded in a single-screw extruder and extruded through a circular die in an inflation apparatus with a die diameter of 33.5 mm and a die slit spacing of 500 μm to obtain a thermoplastic liquid crystal polymer film with an average film thickness of 25 to 100 μm. A 25 μm thick film had a melting point of 310°C, a total light transmittance of 26.8%, a haze value of 99.6%, and an absorption coefficient of 0.053 / μm. A copper-clad laminate was fabricated by laminating the obtained thermoplastic liquid crystal polymer film, which had a thickness of 25 to 100 μm, with JX Metals Corporation's "JXEFL-BHM" copper foil for 5 minutes under conditions of 300°C and 4.0 MPa.

[0080] [Examples 1-5] The copper-clad laminate obtained in the reference example was placed horizontally in a hot air dryer under a nitrogen atmosphere at 330°C and heat-treated for the time shown in Table 7. Then, the copper foil was removed using a ferric chloride solution to obtain a thermoplastic liquid crystal polymer film.

[0081] [Example 6] A thermoplastic liquid crystal polymer film with a thickness of 50 μm, obtained in the same manner as in the reference example, was laminated on both sides with the same type of copper foil under the same conditions to create a double-sided copper-clad laminate. This was then left to stand horizontally for 4 seconds in a hot air dryer under a nitrogen atmosphere at 330°C, and the copper foil was removed using a ferric chloride solution to obtain a thermoplastic liquid crystal polymer film.

[0082] [Comparative Example 1~ 3 ] A copper-clad laminate was prepared by laminating a film of Kuraray Co., Ltd.'s "Vecter" (registered trademark) CTQ 25-100 μm thickness with JX Metals Corporation's "JXEFL-BHM" copper foil at a temperature of 300°C and a pressure of 4.0 MPa for 5 minutes. Subsequently, the copper foil was removed using a ferric chloride solution to obtain a thermoplastic liquid crystal polymer film.

[0083] [Comparative Example] 4、 5] The copper-clad laminate obtained in the reference example was heat-treated at the temperatures and times shown in Table 7. Then, the copper foil was removed using a ferric chloride solution to obtain a thermoplastic liquid crystal polymer film.

[0084] [Table 7]

[0085] [Comparative Examples 6 and 7] In addition to those shown in Table 7, as Comparative Examples 6 and 7, metal-clad laminates were prepared by laminating copper foil onto a thermoplastic liquid crystal polymer film with a thickness of 25 μm obtained in the reference example. These laminates were placed horizontally in a hot air dryer under a nitrogen atmosphere at 330°C, and heat-treated for 600 seconds in Comparative Example 6 and 1800 seconds in Comparative Example 7. After removing the copper foil using a ferric chloride solution, the physical properties of the films were measured. The total light transmittance was lower compared to Example 2, and compared to the films obtained in Examples 1 to 5, the films of Comparative Examples 6 and 7 were both discolored yellow. Furthermore, the thermal expansion coefficient of the films could not be controlled within the predetermined range.

[0086] Figure 2 shows the data for Examples 1-6 and Comparative Examples 1-5, with the extinction coefficient on the vertical axis and the thickness of the thermoplastic liquid crystal polymer film on the horizontal axis. The examples are plotted as diamonds, and the comparative examples are plotted as squares, with ε = 0.21x -0.55 It can be seen that the distribution is bounded by the curve shown.

[0087] As shown in Table 7, the thermoplastic liquid crystal polymer molded articles shown in the heat-treated examples exhibit a lower absorption coefficient, resulting in higher light transmittance and improved visibility compared to comparative examples of the same thickness. This indicates that laminates controlled to such specific higher-order structures have high adhesive strength and excellent heat resistance. On the other hand, in comparative examples 1-5, where no heat treatment was performed on the metal-clad laminates, or where the heat treatment temperature was low, the haze values ​​were high, but the light transmittance was lower and visibility was poorer compared to the examples of the same thickness. Furthermore, in Comparative Examples 4 and 5, the thermal expansion coefficient of the film could not be controlled to a predetermined range. [Industrial applicability]

[0088] The thermoplastic liquid crystal polymer molded articles of the present invention possess both high total light transmittance and ultra-high haze values. Therefore, in addition to conventional applications such as insulators for multilayer circuit boards and electronic circuit boards, reinforcing plates for flexible circuit boards, and cover films for circuit surfaces, they are expected to have applications as diffusers for displays, lighting fixtures, and other devices where a degree of freedom in device design and design flexibility are required. Furthermore, due to the control of microdomain size, they exhibit high adhesion to the substrate and excellent heat resistance, making them extremely useful as insulating materials for electronic circuit boards and the like.

[0089] As described above, preferred embodiments of the present invention have been explained, but those skilled in the art can make various additions, modifications, or deletions without departing from the spirit of the invention, and such additions, modifications, or deletions are also included within the scope of the present invention. [Explanation of Symbols]

[0090] 1. Thermoplastic liquid crystal polymer film 2 Metal foil 3. Stacked precursor 10 Film-like thermoplastic liquid crystal polymer molded body 20 circuit patterns 30 Metal clad laminate 40 Circuit boards

Claims

1. A molded article containing a thermoplastic liquid crystal polymer, Haze value is 99% or higher, The coefficient of thermal expansion is 16 to 27 ppm / °C. The correlation between the absorption coefficient (ε), expressed in units of μm, and the thickness (x), expressed in units of μm, is ε≦0.21×x －０．５５ Satisfying the conditions, The thermoplastic liquid crystal polymer contains repeating units derived from p-hydroxybenzoic acid and repeating units derived from 6-hydroxy-2-naphthoic acid in a molar ratio of 75 / 25 to 80 / 20. Thermoplastic liquid crystal polymer molded product.

2. A thermoplastic liquid crystal polymer molded article according to claim 1, wherein the shape is film-like.

3. A film-like thermoplastic liquid crystal polymer molded article according to claim 2, The film-like molded body comprises a metal layer laminated on at least one surface, Metal-clad laminate.

4. Includes the metal-clad laminate described in claim 3, A circuit board having at least one of the metal layers having a circuit pattern.

5. A laminated circuit board comprising at least one layer of the metal-clad laminate described in claim 3.

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