Manufacturing method of metal-clad laminates

Abstract

The present invention provides a method for manufacturing metal-clad laminates with high interlayer adhesion and few or no voids. [Solution] The present disclosure is a method for manufacturing a metal-clad laminate, in which a metal layer (12) is laminated in contact with a liquid crystal polymer film (LCF) on at least one surface of an insulating layer (11) containing one or more liquid crystal polymer films (LCF) containing a thermoplastic liquid crystal polymer, and comprises the steps of: (S1) supplying one or more liquid crystal polymer films (LCF) and one or more metal foils (MF) to a double belt press device including a pair of endless belts and heat-pressing them to manufacture a pre-laminate in which a metal layer (12) is laminated on at least one surface of an insulating layer (11) containing one or more liquid crystal polymer films (LCF); and (S2) supplying the obtained pre-laminate to a roll press device including a pair of heated and pressurized rolls and heat-pressing them.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing metal-clad laminates. [Background technology]

[0002] Thermoplastic liquid crystal polymers (also simply called liquid crystal polymers) are used in applications such as insulating layers for metal-clad laminates, which are materials for wiring boards, due to their characteristics such as low transmission loss, high heat resistance, low water absorption, low thermal expansion coefficient, chemical resistance, high modulus of elasticity, and high internal loss. In this specification, unless otherwise specified, "wiring board" includes multilayer wiring boards. A metal foil can be layered onto at least one surface of a liquid crystal polymer film and heat-pressed to obtain a single-sided or double-sided metal-clad laminate. A wiring layer (also called a circuit) containing wiring can be formed using the metal foil on the surface of this metal-clad laminate to obtain a wiring substrate. Furthermore, a multilayer wiring substrate can be obtained by repeating the lamination of metal-clad laminates and the formation of wiring layers (circuits) one or more times on the obtained wiring substrate. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2010-221694 [Patent Document 2] Japanese Patent Publication No. 2016-129949 [Patent Document 3] International Publication No. 2020 / 090688 [Patent Document 4] International Publication No. 2020 / 153391 [Patent Document 5] Japanese Patent Application Publication No. 5-42603 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, applications such as portable electronic devices have seen advancements in communication speed and capacity, leading to higher signal frequencies. Wiring boards used in these applications require reduced transmission loss in the high-frequency range. Transmission loss includes conductor loss caused by the surface resistance of the metal foil. In wiring boards, high interlayer adhesion between the liquid crystal polymer film and the metal foil is desirable. One technique to improve interlayer adhesion between the liquid crystal polymer film and the metal foil involves roughening the surface of the metal foil on the liquid crystal polymer film side. However, this technique is undesirable because it tends to cause high-frequency current loss. From the viewpoint of reducing transmission loss in the high-frequency range, it is preferable to obtain high adhesion even when using metal foil with a small surface roughness.

[0005] The surface of the liquid crystal polymer film before lamination with the metal foil may have one or more dents (indentations). When the liquid crystal polymer film and the metal foil are laminated together, air may be trapped between them. During heat-pressing, volatile organic components may be generated between the liquid crystal polymer film and the metal layer. Due to these factors, the metal-clad laminate obtained by laminating a metal foil onto at least one surface of the liquid crystal polymer film and heat-pressing it may have one or more voids between the liquid crystal polymer film and the metal foil. The presence of one or more voids in a wiring board is undesirable because it may lead to circuit malfunctions such as broken wires. Components are mounted on the surface of the wiring board using high-temperature solder heated above the melting point of the liquid crystal polymer film. If there is one or more voids in the metal-clad laminate, one or more voids may expand due to heat during component mounting, potentially causing bulging, which is undesirable.

[0006] Conventional methods for manufacturing metal-clad laminates include a method of laminating a liquid crystal polymer film and a metal foil using a double-belt press device (Patent Document 1, Claim 1, Figure 1; Patent Document 2, Claim 2, Figure 1; Patent Document 3, Claim 7, Figure 5; Patent Document 4, Claim 1, Figure 1). In this method, compared to the later method using a roll press, thermocompression bonding is performed under conditions of low surface pressure, high temperature, and long duration. In this method, because heat bonding is performed at low surface pressure, it is difficult to improve the interlayer adhesion between the liquid crystal polymer film and the metal foil. In particular, when using metal foil with a low surface roughness, it is difficult to improve the interlayer adhesion between the liquid crystal polymer film and the metal foil.

[0007] Another conventional method for manufacturing metal-clad laminates involves laminating a liquid crystal polymer film with a metal foil using a roll press device (Claim 1 of Patent Document 5). In this method, compared to the aforementioned method using a double belt press device, thermocompression bonding is performed under conditions of high surface pressure, low temperature, and short duration. This method allows for heat-compression bonding at high surface pressure, thereby improving the interlayer adhesion between the liquid crystal polymer film and the metal foil. However, this method involves thermocompression bonding under low temperature and short time conditions, which may result in the formation of one or more voids in the resulting metal-clad laminate.

[0008] This disclosure is made in view of the above circumstances and aims to provide a method for manufacturing metal-clad laminates that have high interlayer adhesion and are free of or have few voids. [Means for solving the problem]

[0009] This disclosure provides a method for manufacturing a metal-clad laminate. [1] A method for manufacturing a metal-clad laminate comprising an insulating layer containing one or more liquid crystal polymer films containing a thermoplastic liquid crystal polymer, wherein a metal layer is laminated on at least one surface of the liquid crystal polymer film in contact with the liquid crystal polymer film, Step (S1) involves supplying one or more liquid crystal polymer films and one or more metal foils to a double belt press device including a pair of endless belts, and heat-pressing them to produce a pre-laminate in which the metal layers are laminated on at least one surface of the insulating layer including one or more liquid crystal polymer films, A method for manufacturing a metal-clad laminate, comprising a step (S2) of supplying the preliminary laminate to a roll press device including a pair of heating and pressurizing rolls and performing thermocompression bonding.

[0010] [2] In step (S1), when the maximum heating temperature (T max ) is Tm - 15[°C] to Tm + 20[°C], where Tm [°C] is the melting point of the liquid crystal polymer film, the pressure is 0.5 to 10 MPa, and the time during which the temperature of T max [°C] to T max - 10[°C] is maintained is 10 to 360 seconds, thermocompression bonding is performed. The method for manufacturing a metal-clad laminate according to [1].

[0011] [3] In step (S2), when the heating temperature is Tm - 150°C to Tm - 10°C, where Tm [°C] is the melting point of the liquid crystal polymer film, the pressure is 10 to 40 MPa, and the thermocompression bonding time is 0.0001 to 5.0 seconds, thermocompression bonding is performed. The method for manufacturing a metal-clad laminate according to [1] or [2].

[0012] [4] The preliminary laminate has an interlayer peeling strength in at least one direction between the liquid crystal polymer film and the metal layer of 0.20 to 5.00 N / mm, measured in accordance with JIS C 6471:1995. The method for manufacturing a metal-clad laminate according to any one of [1] to [3]. [5] The metal-clad laminate has an interlayer peeling strength in at least one direction between the liquid crystal polymer film and the metal layer of 0.42 to 5.00 N / mm, measured in accordance with JIS C 6471:1995. The method for manufacturing a metal-clad laminate according to any one of [1] to [4].

[0013] [6] The metal layer has a ten-point height of the area (S10z) of 0 to 2.30 μm on the surface in contact with the liquid crystal polymer film, measured in accordance with ISO25178 - 71(2017). The method for manufacturing a metal-clad laminate according to any one of [1] to [5]. [7] The metal-clad laminate has an area of 15,000 mm 2A method for manufacturing a metal-clad laminate according to any of [1] to [6], wherein the number of voids with a diameter of 5 μm or more per unit area is 0 to 15.

[0014] [8] The thermoplastic liquid crystal polymer comprises one or more aromatic compounds selected from the group consisting of aromatic polyesters, aromatic polyesteramides, and aromatic polyamides. A method for producing a metal-clad laminate according to any one of [1] to [7]. [9] A method for producing a metal-clad laminate according to any one of [1] to [8], wherein the thermoplastic liquid crystal polymer comprises an aromatic polyester having 4-hydroxybenzoic acid units and / or 6-hydroxy-2-naphthoic acid units.

[10] A method for manufacturing a metal-clad laminate according to any of [1] to [9], wherein the thickness of the liquid crystal polymer film is 10 to 500 μm and the thickness of the metal layer is 1 to 200 μm. [Effects of the Invention]

[0015] According to this disclosure, it is possible to provide a method for manufacturing metal-clad laminates that have high interlayer adhesion and are free from or have few voids. [Brief explanation of the drawing]

[0016] [Figure 1] These are schematic cross-sectional views of metal-clad laminates according to the first and second embodiments of the present invention. [Figure 2] This is a process diagram of the method for manufacturing a metal-clad laminate according to the present disclosure. [Figure 3] This is a process diagram of the method for manufacturing a metal-clad laminate according to the present disclosure. [Figure 4] This is a process diagram of the method for manufacturing a metal-clad laminate according to the present disclosure. [Modes for carrying out the invention]

[0017] Generally, thin film molded articles are referred to as "films" and "sheets," depending on their thickness, but there is no clear distinction between them. Unless otherwise specified, the term "film" in this specification includes "sheets." In this specification, unless otherwise specified, the "high frequency region" is defined as the region with a frequency of 1 GHz or higher. In this specification, (heat) crimping is a general term encompassing both non-heat crimping and heat crimping.

[0018] [Metal-clad laminate] This disclosure relates to a metal-clad laminate in which a metal layer is laminated in contact with a liquid crystal polymer film on at least one surface of an insulating layer comprising one or more liquid crystal polymer films comprising one or more thermoplastic liquid crystal polymers. Figure 1 shows schematic cross-sectional views of metal-clad laminates according to the first and second embodiments of the present invention. The metal-clad laminate 1 is a single-sided metal-clad laminate in which a metal layer 12 is laminated on one side of an insulating layer 11 containing one or more liquid crystal polymer films LCF (in the illustrated example, consisting of one liquid crystal polymer film LCF), in contact with the liquid crystal polymer film LCF. The metal-clad laminate 2 is a double-sided metal-clad laminate in which a metal layer 12 is laminated on both sides of an insulating layer 11 containing one or more liquid crystal polymer films LCF (in the illustrated example, consisting of one liquid crystal polymer film LCF), in contact with the liquid crystal polymer film LCF. The metal-clad laminate of this disclosure is suitable for use as a wiring board.

[0019] The thickness of the liquid crystal polymer film (LCF) is preferably 10 to 500 μm. The lower limit is preferably 20 μm, more preferably 25 μm, even more preferably 30 μm, even more preferably 35 μm, even more preferably 40 μm, particularly preferably 45 μm, and most preferably 50 μm. The upper limit is more preferably 450 μm, even more preferably 400 μm, even more preferably 350 μm, even more preferably 300 μm, even more preferably 250 μm, even more preferably 200 μm, particularly preferably 150 μm, and most preferably 100 μm. The liquid crystal polymer film (LCF) may be a laminated film obtained by (thermal) bonding multiple liquid crystal polymer films together.

[0020] The insulating layer 11 may optionally include one or more insulating members other than the liquid crystal polymer film LCF. Examples of insulating members include fibrous fillers made of thermoplastic liquid crystal polymer or other materials; fibrous structures (woven fabrics and nonwoven fabrics, etc.) made of thermoplastic liquid crystal polymer or other materials; and thermoplastic or thermosetting resins other than thermoplastic liquid crystal polymer. However, the metal layer 12 is laminated on the liquid crystal polymer film LCF in contact with the liquid crystal polymer film LCF.

[0021] The metal layer 12 is preferably made of metal foil MF. Due to its low electrical resistance, copper foil, silver foil, gold foil, aluminum foil, and combinations thereof are preferred as the metal foil, with copper foil being more preferred. A metal-clad laminate using copper foil as the metal foil is called a copper-clad laminate (CCL). The metal foil may have a metal plating layer on its surface. The metal foil may also be a carrier-equipped metal foil, comprising an ultrathin metal foil and a carrier metal foil supporting it. The metal foil may be a roughened metal foil or a non-roughened metal foil. The metal foil may have at least one surface treated with a known surface treatment.

[0022] The thickness of the metal layer 12 is not particularly limited, but is preferably 1 to 200 μm as it is suitable for circuit formation. The lower limit is more preferably 2 μm, even more preferably 3 μm, even more preferably 4 μm, even more preferably 5 μm, even more preferably 6 μm, even more preferably 7 μm, particularly preferably 8 μm, and most preferably 10 μm. The upper limit is more preferably 180 μm, even more preferably 150 μm, even more preferably 120 μm, even more preferably 100 μm, even more preferably 80 μm, even more preferably 50 μm, particularly preferably 30 μm, and most preferably 20 μm.

[0023] The surface roughness of the surface 12S of the metal layer 12 that contacts the liquid crystal polymer film LCF is not particularly limited. If the surface roughness of the surface 12S of the metal layer 12 that contacts the liquid crystal polymer film LCF is high, the interlayer adhesion between the liquid crystal polymer film LCF and the metal layer 12 can be improved, but high-frequency current loss is likely to occur, which is undesirable. In the technology disclosed herein, even if the surface roughness of the surface 12S of the metal layer 12 that is in contact with the liquid crystal polymer film LCF is low, the interlayer adhesion between the liquid crystal polymer film LCF and the metal layer 12 can be improved. In the technology disclosed herein, even if a low-roughness roughened metal foil or a non-roughened metal foil with low surface roughness is used as the material for the metal layer 12, the interlayer adhesion between the liquid crystal polymer film LCF and the metal layer 12 can be improved. Metal-clad laminates 1 and 2, in which the surface roughness of the surface 12S of the metal layer 12 in contact with the liquid crystal polymer film LCF is low, have low conductor loss due to the surface resistance of the metal layer 12, low transmission loss in the high-frequency range, and can have good high-frequency characteristics.

[0024] One parameter for surface roughness is the ten-point region height (S10z). The height of the ten-point region (S10z) of the surface 12S of the metal layer 12 in contact with the liquid crystal polymer film is preferably 0 to 2.3 μm. The lower limit is not particularly limited and can be, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm, 0.7 μm, 1.0 μm, 1.2 μm, 1.4 μm, or 1.5 μm. The upper limit is more preferably 2.2 μm, even more preferably 2.0 μm, even more preferably 1.9 μm, even more preferably 1.8 μm, particularly preferably 1.7 μm, and most preferably 1.6 μm. The "ten-point region height (S10z)" can be measured in accordance with ISO 25178-71 (2017) by the method described in the [Examples] section below.

[0025] Interlaminar adhesion can be indicated by the delamination strength. The peel strength between the liquid crystal polymer film (LCF) and the metal layer 12 in at least one direction, as measured in accordance with JIS C 6471:1995, can be 0.42 to 5.00 N / mm. The lower limit is more preferably 0.45 N / mm, even more preferably 0.47 N / mm, even more preferably 0.50 N / mm, even more preferably 0.52 N / mm, even more preferably 0.55 N / mm, particularly preferably 0.57 N / mm, and most preferably 0.60 N / mm. The upper limit can be 4.00 N / mm, 3.50 N / mm, 3.00 N / mm, 2.50 N / mm, 2.00 N / mm, 1.50 N / mm, or 1.20 N / mm. The delamination strength can be measured by the method described in the [Examples] section below.

[0026] The metal-clad laminates of this disclosure are manufactured by a manufacturing method using a roll-to-roll process. In the metal-clad laminate of this disclosure, the delamination strength between the liquid crystal polymer film LCF and the metal layer 12 can be within the above range in at least one of the directions of travel (MD (Machine Direction) or longitudinal direction) and the width direction (TD (Transverse Direction) or transverse direction) in the roll-to-roll process. In the metal-clad laminate of this disclosure, the interlayer peel strength between the liquid crystal polymer film LCF and the metal layer 12 can be within the above range in both the MD and TD directions in the roll-to-roll process.

[0027] According to the technology of this disclosure, it is possible to manufacture metal-clad laminates that are free of or have few voids. The metal-clad laminate of this disclosure has an area of ​​15,000 mm². 2 The number of voids with a diameter of 5 μm or more per unit area can be between 0 and 15. The upper limit is more preferably 12, even more preferably 10, even more preferably 8, even more preferably 5, even more preferably 4, particularly preferably 3, and most preferably 2. The metal-clad laminate of this disclosure has an area of ​​15,000 mm². 2 The number of voids with a diameter of 5 μm or more per unit area can be 0 or 1, and it is also possible to set it to 0. Area 15,000mm 2 The number of voids with a diameter of 5 μm or more per unit area can be measured by the method described in the [Examples] section below.

[0028] [Manufacturing method for metal-clad laminates] The metal-clad laminate of this disclosure is manufactured by a manufacturing method using a roll-to-roll process, and comprises steps (S1) and (S2). Process (S1) and process (S2) may be continuous or discontinuous.

[0029] <Process (S1)> In process (S1), a double-belt press device can be used to laminate one or more liquid crystal polymer films with one or more metal layers. As shown in Figure 2, one or more liquid crystal polymer films (LCF) and one or more metal foils (MF) are supplied to a double belt press apparatus (DBPS) including a pair of endless belts (EB) and heat-compressed. After heat-compression bonding, a pre-laminate (LB) can be obtained in which a metal layer made of metal foils (MF) is laminated on at least one surface of an insulating layer containing one or more liquid crystal polymer films (LCF) in contact with the liquid crystal polymer films (LCF).

[0030] The liquid crystal polymer film (LCF) is unwound from a liquid crystal polymer film roll (not shown) and continuously supplied to a double belt press machine. The metal foil MF is unwound from a metal foil roll (not shown) and continuously supplied to a double belt press machine. In a double belt press (DBPS), one or more heat blocks (HB) are placed within each endless belt (EB). Each heat block (HB) contains one or more heaters (H) and pressurized oil (O) for pressurizing the laminate that passes between the pair of endless belts (EB). In the figure, the symbol P represents a pulley that rotates the endless belt (EB). Figure 2 illustrates a case in which metal foils MF are laminated on both sides of an insulating layer made of a single liquid crystal polymer film (LCF), thereby obtaining a pre-laminate LB having a laminated structure of first metal foil MF / liquid crystal polymer film (LCF) / second metal foil MF.

[0031] In step (S1), if necessary, one or two known protective films (e.g., polyimide films) may be continuously supplied to the double belt press apparatus DBPS simultaneously with the one or more liquid crystal polymer films LCF and one or more metal foils MF to protect at least one side of a laminate comprising one or more insulating layers including one or more liquid crystal polymer films LCF and one or more metal layers. The protective films may be peeled off after the completion of step (S1), or the next step may be carried out using the pre-laminated laminate LB with the protective films attached.

[0032] The method using a double-belt press allows for heat bonding under conditions of lower surface pressure, higher temperature, and longer duration, compared to the method using a roll press. Figure 2 schematically shows the relationship between the position in the direction of travel (MD) and the applied pressure, and the relationship between the position in the direction of travel (MD) and the heating temperature, using bar graphs.

[0033] In process (S1), the maximum heating temperature (T max The range is not particularly limited, but is preferably Tm-15[°C] to Tm+20[°C], where Tm[°C] is the melting point of the liquid crystal polymer film. The lower limit is more preferably Tm-12[°C], and particularly preferably Tm-10[°C]. The upper limit is more preferably Tm+15[°C], even more preferably Tm+10[°C], even more preferably Tm+5[°C], particularly preferably Tm-1[°C], and most preferably Tm-5[°C].

[0034] The pressing force (surface pressure) by a pair of endless belts is not particularly limited, and is preferably 0.5 to 10.0 MPa. The lower limit value is more preferably 1.0 MPa, still more preferably 1.5 MPa, still more preferably 2.0 MPa, still more preferably 2.5 MPa, still more preferably 3.0 MPa, still more preferably 3.5 MPa, still more preferably 4.0 MPa, particularly preferably 4.5 MPa, and most preferably 5.0 MPa. The upper limit value is more preferably 9.0 MPa, still more preferably 8.5 MPa, still more preferably 8.0 MPa, particularly preferably 7.5 MPa, and most preferably 7.0 MPa.

[0035] T max [℃]~T max The time during which the temperature of -10 [°C] is maintained is not particularly limited, and is preferably 10 to 360 seconds. The lower limit value is more preferably 20 seconds, still more preferably 30 seconds, particularly preferably 40 seconds, and most preferably 50 seconds. The upper limit value is more preferably 270 seconds, still more preferably 240 seconds, still more preferably 210 seconds, still more preferably 180 seconds, particularly preferably 150 seconds, and most preferably 120 seconds.

[0036] The surface of the liquid crystal polymer film before laminating with the metal layer may have one or more dents (depressions). When the liquid crystal polymer film and the metal foil are overlapped, air may be trapped between them. During thermocompression bonding, volatile substances of organic components may be generated between the liquid crystal polymer film and the metal layer. Due to these factors, one or more voids may be generated between the liquid crystal polymer film and the metal layer. If there are one or more voids in the wiring board, there is a risk of circuit defects such as disconnection of the wiring, which is not preferable. Components are mounted on the surface of the wiring board using high-temperature solder heated to a temperature equal to or higher than the melting point of the liquid crystal polymer film. If there are one or more voids in the metal-clad laminate, when components are mounted, one or more voids may thermally expand and cause swelling, which is not preferable. In step (S1), the liquid crystal polymer film and the metal layer can be heat-pressed together at a high temperature for a long period of time, and the liquid crystal polymer, softened or melted at the high temperature, can fill one or more voids. As a result, a pre-laminate with few or no voids can be obtained.

[0037] The pre-laminate obtained after step (S1) may have an interlaminar peel strength between the liquid crystal polymer film and the metal layer in at least one direction, measured in accordance with JIS C 6471:1995, preferably 0.20 to 5.00 N / mm. The lower limit is more preferably 0.22 N / mm, even more preferably 0.25 N / mm, even more preferably 0.27 N / mm, particularly preferably 0.30 N / mm, and most preferably 0.32 N / mm. The upper limit may be 4.50 N / mm, 4.00 N / mm, 3.50 N / mm, 3.00 N / mm, 2.50 N / mm, 2.00 N / mm, 1.50 N / mm, or 1.00 N / mm. The pre-laminate obtained after step (S1) can have an interlayer peel strength between the liquid crystal polymer film and the metal layer within the above range in at least one of the MD and TD directions in the roll-to-roll process. The pre-laminate obtained after step (S1) can have an interlayer peel strength between the liquid crystal polymer film and the metal layer within the above range in both the MD and TD directions in the roll-to-roll process.

[0038] <Process (S2)> As shown in Figure 3, the pre-laminate LB obtained after step (S1) is supplied to a roll press apparatus RPS including a pair of heated and pressurized rolls R, and thermocompressed. After thermocompression, a metal-clad laminate CCL can be obtained in which a metal layer made of metal foil MF is laminated on at least one surface of an insulating layer containing one or more liquid crystal polymer films LCF, in contact with the liquid crystal polymer film LCF. The heat-pressure roll R is not particularly limited and examples include heat-resistant rubber rolls and metal rolls. The pair of heat-pressure rolls R may be a combination of different types of rolls. Figure 3 illustrates a case in which metal foil MF is laminated on both sides of a liquid crystal polymer film (LCF) to obtain a metal-clad laminate (CCL) having a laminated structure of first metal foil MF / liquid crystal polymer film (LCF) / second metal foil MF.

[0039] As shown in Figure 4, after step (S1), a preliminary laminate LB is obtained in which metal foil MF is laminated on one side of the liquid crystal polymer film LCF. This preliminary laminate LB and the metal foil MF are then supplied to a roll press device RPS and heat-pressed to obtain a metal-clad laminate CCL in which metal foil MF is laminated on both sides of the liquid crystal polymer film LCF.

[0040] In step (S2), if necessary, one or two known protective films (e.g., polyimide films) may be continuously supplied to the roll press apparatus RPS simultaneously with the pre-laminate LB to protect at least one side of the pre-laminate LB. If a pre-laminated laminate LB with a protective film is obtained after process (S1), the pre-laminated laminate LB with the protective film may be continuously supplied to the roll press device RPS. The protective film can be peeled off after the completion of process (S2).

[0041] Compared to the method using a roll press, the method using a double belt press allows for heat bonding under conditions of high surface pressure, low temperature, and short duration. Figure 3 schematically shows the relationship between the position in the direction of travel (MD) and the applied pressure, and the relationship between the position in the direction of travel (MD) and the heating temperature, using bar graphs. This method allows for thermocompression bonding at high surface pressure, making it possible to obtain a metal-clad laminate with high interlayer adhesion between the liquid crystal polymer film and the metal layer.

[0042] In step (S2), the applied pressure (surface pressure) is not particularly limited, but is preferably 10 to 40 MPa from the viewpoint of improving interlayer adhesion between the liquid crystal polymer film and the metal layer. The lower limit is more preferably 12 MPa, even more preferably 15 MPa, particularly preferably 18 MPa, and most preferably 20 MPa. The upper limit is more preferably 38 MPa, even more preferably 35 MPa, even more preferably 32 MPa, even more preferably 30 MPa, particularly preferably 28 MPa, and most preferably 25 MPa. The applied pressure (surface pressure) referred to here is the value obtained by dividing the load applied to the laminate by the pair of heated and pressurized rolls by the effective area of ​​the heated and pressurized rolls. The effective area of ​​the heated and pressurized roll can be measured as follows: By pressing a single heated and pressurized roll onto pressure-sensitive paper without rotating it, the width and length of the shape imprinted on the paper can be measured, and their product can be calculated as the effective area.

[0043] In step (S2), the heating temperature (temperature of the pair of heating and pressing rolls) is not particularly limited, but from the viewpoint of interlayer adhesion between the liquid crystal polymer film and the metal layer, and suppression of stretching of the liquid crystal polymer film, when the melting point of the liquid crystal polymer film is Tm[°C], it is preferably Tm-150[°C] to Tm-10[°C]. The lower limit is more preferably Tm-140[°C], even more preferably Tm-130[°C], even more preferably Tm-120[°C], even more preferably Tm-110[°C], even more preferably Tm-100[°C], particularly preferably Tm-90[°C], and most preferably Tm-80[°C]. The upper limit is more preferably Tm-20[°C], even more preferably Tm-30[°C], particularly preferably Tm-40[°C], and most preferably Tm-50[°C].

[0044] In step (S2), the heat-pressing time is not particularly limited, but is preferably 0.0001 to 5.0 seconds. The lower limit is more preferably 0.0005 seconds, even more preferably 0.001 seconds, even more preferably 0.005 seconds, even more preferably 0.01 seconds, particularly preferably 0.05 seconds, and most preferably 0.1 seconds. The upper limit is more preferably 4.5 seconds, even more preferably 4.0 seconds, even more preferably 3.5 seconds, even more preferably 3.0 seconds, even more preferably 2.5 seconds, even more preferably 2.0 seconds, particularly preferably 1.5 seconds, and most preferably 1.0 seconds.

[0045] In the manufacturing method of this disclosure, one or more voids can be eliminated or reduced by step (S1), and interlayer adhesion can be improved by step (S2). Therefore, according to this disclosure, it is possible to provide a method for manufacturing metal-clad laminates that have high interlayer adhesion and are free from or have few voids.

[0046] [Thermoplastic liquid crystal polymer] A "thermoplastic liquid crystal polymer" is a thermoplastic polymer capable of forming an optically anisotropic molten phase. The fact that "a sample can form an optically anisotropic molten phase" can be confirmed, for example, by heating a sample placed on a hot stage under a nitrogen atmosphere and observing the transmitted light from the sample.

[0047] The thermoplastic liquid crystal polymer contained in the liquid crystal polymer film is not particularly limited and includes aromatic polyesters (preferably fully aromatic polyesters); aromatic polyesteramides obtained by introducing an amide group into an aromatic polyester; aromatic polyamides (preferably fully aromatic polyamides); and aromatic compounds obtained by introducing one or more functional groups other than amide groups, such as an imide group, a carbonate group, a carbodiimide group, and an isocyanurate group, into an aromatic polyester, aromatic polyesteramide, or aromatic polyamide. The thermoplastic liquid crystal polymer preferably contains one or more aromatic compounds selected from the group consisting of aromatic polyesters, aromatic polyesteramides, and aromatic polyamides.

[0048] In this specification, "aromatic polyester (amide)" is a general term for aromatic polyester and aromatic polyesteramide. Examples of raw material monomers for aromatic polyesters (amides) include (1) aromatic or aliphatic diols, (2) aromatic or aliphatic dicarboxylic acids, (3) aromatic hydroxycarboxylic acids, (4) amino group-containing aromatic compounds such as aromatic diamines, aromatic hydroxyamines, and aromatic aminocarboxylic acids, and (5) derivatives thereof (e.g., acid anhydrides). Specific examples of these are shown below.

[0049] (1) Aromatic or aliphatic diols [ka]

[0050] (2) Aromatic or aliphatic dicarboxylic acids [ka]

[0051] (3) Aromatic hydroxycarboxylic acid [ka]

[0052] (4) Aromatic compounds containing amino groups, such as aromatic diamines, aromatic hydroxyamines, and aromatic aminocarboxylic acids. [ka]

[0053] Specific examples of aromatic polyesters (amides) include copolymers containing one or more units selected from the group consisting of the units shown in [Chemical Formula 5] and [Chemical Formula 6] below.

[0054] [ka]

[0055] [ka]

[0056] Aromatic polyesters (amides) preferably contain units that include a naphthalene skeleton. As the aromatic polyester (amide), a copolymer is preferred that contains, for example, a unit (A) derived from hydroxybenzoic acid and / or a unit (B) derived from hydroxynaphthoic acid, and may further contain one or more other units as needed.

[0057] The preferred unit (A) is the 4-hydroxybenzoic acid (HBA) unit represented by the following formula (A). The preferred unit (B) is the 6-hydroxy-2-naphthoic acid (HNA) unit represented by the following formula (B).

[0058] [ka]

[0059] The aromatic polyester (amide) preferably contains 4-hydroxybenzoic acid (HBA) units and / or 6-hydroxy-2-naphthoic acid (HNA) units. As the aromatic polyester (amide), a copolymer (HBA-HNA) containing 4-hydroxybenzoic acid (HBA) units and 6-hydroxy-2-naphthoic acid (HNA) units is particularly preferred. The melting point (Tm0) of the copolymer (HBA-HNA), the melt shear viscosity under the conditions of Tm0 + 15°C and shear strain rate of 0.1 rad / s, and the melt shear viscosity under the conditions of Tm0 + 15°C and shear strain rate of 100 rad / s can be adjusted by the content of 4-hydroxybenzoic acid (HBA) units and 6-hydroxy-2-naphthoic acid (HNA) units in the copolymer (HBA-HNA).

[0060] The content of 4-hydroxybenzoic acid (HBA) units in the copolymer (HBA-HNA) is not particularly limited, but is preferably 5 to 95 mol%. The lower limit is more preferably 10 mol%, even more preferably 20 mol%, even more preferably 30 mol%, even more preferably 40 mol%, even more preferably 50 mol%, particularly preferably 60 mol%, and most preferably 70 mol%. The upper limit is more preferably 90 mol%, particularly preferably 85 mol%, and most preferably 80 mol%.

[0061] The content of 6-hydroxy-2-naphthoic acid (HNA) units in the copolymer (HBA-HNA) is not particularly limited, but is preferably 95 to 5 mol%. The upper limit is more preferably 90 mol%, even more preferably 80 mol%, even more preferably 70 mol%, even more preferably 60 mol%, even more preferably 50 mol%, particularly preferably 40 mol%, and most preferably 30 mol%. The lower limit is more preferably 10 mol%, particularly preferably 15 mol%, and most preferably 20 mol%.

[0062] The total amount of 4-hydroxybenzoic acid (HBA) units and 6-hydroxy-2-naphthoic acid (HNA) units in the copolymer (HBA-HNA) is preferably 50 to 100 mol%. The lower limit is more preferably 50 mol%, even more preferably 60 mol%, 70 mol%, particularly preferably 80 mol%, and most preferably 90 mol%.

[0063] Other units that can be included in copolymers (HBA-HNA) include units derived from aromatic diols, aromatic dicarboxylic acids, aromatic hydroxyamines, and their derivatives. Examples of aromatic diols include 4,4'-dihydroxybiphenyl, hydroquinone, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of aromatic hydroxyamines include 4-aminophenol and 4-amino-4'-hydroxybiphenyl. The content of other units in the copolymer (HBA-HNA) (total amount if there are multiple types) is preferably 50 to 0 mol%. The upper limit is more preferably 40 mol%, 30 mol%, particularly preferably 20 mol%, and most preferably 10 mol%.

[0064] Aromatic polyamides may contain one or more units derived from amino group-containing aromatic compounds such as aromatic diamines, aromatic hydroxyamines, and aromatic aminocarboxylic acids. Aromatic polyamides may further contain one or more units derived from amino group-non-containing aromatic compounds such as aromatic dicarboxylic acids, as needed. Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminodiphenyl sulfone. Examples of aromatic hydroxyamines include 4-aminophenol and 4-amino-4'-hydroxybiphenyl. Examples of aromatic aminocarboxylic acids include 4-aminobenzoic acid. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and diphenyl ether-4,4'-dicarboxylic acid.

[0065] Examples of aromatic polyamides include copolymers containing units derived from aromatic diamines and units derived from aromatic dicarboxylic acids. Specific examples include polyp-phenylene terephthalamide containing p-phenylenediamine units and terephthalic acid units; polym-phenylene isophthalamide containing m-phenylenediamine units and isophthalic acid units; and copolymer p-phenylene·3,4'-oxydiphenylene terephthalamide containing p-phenylenediamine units, 3,4'-diaminodiphenyl ether units, and terephthalic acid units.

[0066] The melting point (Tm0) of the thermoplastic liquid crystal polymer is not particularly limited, but is preferably 200 to 380°C. The lower limit is more preferably 220°C, even more preferably 250°C, even more preferably 260°C, particularly preferably 270°C, and most preferably 280°C. The upper limit is more preferably 370°C, even more preferably 360°C, even more preferably 350°C, even more preferably 340°C, particularly preferably 330°C, and most preferably 320°C.

[0067] The melting point (Tm0) of a thermoplastic liquid crystal polymer can be measured using a differential scanning calorimeter as follows. A 10 mg sample is placed in an aluminum pan and set in the apparatus described above. After purging with nitrogen for 30 minutes or more, the sample is heated from room temperature (20-25°C) to 400°C at a rate of 10°C / min in a 10 ml / min nitrogen stream, held for 5 minutes, and then cooled to 50°C at a rate of 10°C / min (primary scan). Next, the sample is heated to 400°C at a rate of 10°C / min (secondary scan), and the DSC curve is measured. The endothermic peak temperature obtained from the DSC curve obtained in the secondary scan can be determined as the melting point (Tm0) of the thermoplastic liquid crystal polymer. Furthermore, the melting point of the thermoplastic liquid crystal polymer contained in the liquid crystal polymer film can be the same as the melting point of the thermoplastic liquid crystal polymer raw material before the film is made, unless special treatments such as heat resistance treatment are performed.

[0068] The thermoplastic liquid crystal polymer preferably has a melt shear viscosity of 3,000 to 90,000 Pa·s at a temperature of Tm0+15°C and a shear strain rate of 0.1 rad / s, and a melt shear viscosity of 80 to 1,000 Pa·s at a temperature of Tm0+15°C and a shear strain rate of 100 rad / s.

[0069] Under the conditions of a temperature of Tm0 + 15℃ and a shear strain rate of 0.1 rad / s, the lower limit of the molten shear viscosity is more preferably 3,500 Pa·s, even more preferably 4,000 Pa·s, particularly preferably 4,500 Pa·s, and most preferably 5,000 Pa·s. The upper limit is more preferably 80,000 Pa·s, even more preferably 70,000 Pa·s, even more preferably 60,000 Pa·s, even more preferably 50,000 Pa·s, even more preferably 40,000 Pa·s, even more preferably 30,000 Pa·s, even more preferably 20,000 Pa·s, even more preferably 10,000 Pa·s, particularly preferably 9,000 Pa·s, and most preferably 8,000 Pa·s.

[0070] Under the conditions of a temperature of Tm0 + 15℃ and a shear strain rate of 100 rad / s, the lower limit of the molten shear viscosity is more preferably 85 Pa·s, and particularly preferably 90 Pa·s. The upper limit is more preferably 900 Pa·s, even more preferably 800 Pa·s, even more preferably 700 Pa·s, even more preferably 600 Pa·s, even more preferably 500 Pa·s, even more preferably 400 Pa·s, even more preferably 300 Pa·s, particularly preferably 200 Pa·s, and most preferably 100 Pa·s.

[0071] The melting point (Tm0) of a thermoplastic liquid crystal polymer, the melt shear viscosity under the conditions of Tm0 + 15°C and a shear strain rate of 0.1 rad / s, and the melt shear viscosity under the conditions of Tm0 + 15°C and a shear strain rate of 100 rad / s can be adjusted by the monomer unit composition of the thermoplastic liquid crystal polymer.

[0072] The melt shear viscosity of thermoplastic liquid crystal polymers can be measured as follows. A rotary viscoelasticity measuring rheometer (TA Instruments "ARES-G2") is fitted with a pair of parallel plates with a diameter of 25 mm (gap: 1.00 mm), and the melt shear viscosity of thermoplastic liquid crystal polymers can be measured in an air atmosphere under the following conditions: measurement mode: Dynamic Frequency Sweep Test, initial strain: 10%, shear strain rate: 0.1 rad / s or 100 rad / s, transducer detection torque: 0.02~200 g·cm, and temperature: melting point (Tm0) + 15°C.

[0073] (optional ingredient) The liquid crystal polymer film may optionally contain one or more other thermoplastic polymers besides the thermoplastic liquid crystal polymer. Examples of other thermoplastic polymers include polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyether ether ketone, and fluororesin.

[0074] Liquid crystal polymer films may contain one or more types of additives as needed. Examples of additives include inorganic fillers such as titanium dioxide, kaolin, silica, and barium oxide; colorants such as dyes and pigments (e.g., carbon black); and antioxidants, light stabilizers, infrared absorbers, ultraviolet absorbers, and the like.

[0075] (Melting point) The melting point (Tm) of the liquid crystal polymer film is not particularly limited, but is preferably 200 to 380°C. The lower limit is more preferably 220°C, even more preferably 250°C, even more preferably 260°C, particularly preferably 270°C, and most preferably 280°C. The upper limit is more preferably 370°C, even more preferably 360°C, even more preferably 350°C, even more preferably 340°C, particularly preferably 330°C, and most preferably 320°C. The melting point (Tm) of the liquid crystal polymer film can be measured by the method described in the [Examples] section below.

[0076] (Molecular orientation degree (SOR)) The degree of molecular orientation (SOR) of the liquid crystal polymer film is not particularly limited, but isotropic or close to isotropic is preferred, and is preferably 0.5 to 1.5. The lower limit is more preferably 0.6, even more preferably 0.7, even more preferably 0.8, even more preferably 0.85, particularly preferably 0.9, and most preferably 0.95. The upper limit is more preferably 1.45, even more preferably 1.4, even more preferably 1.35, even more preferably 1.3, particularly preferably 1.25, and most preferably 1.2. SOR (Segment Orientation Ratio) is an index of the degree of molecular orientation for a segment composed of molecules, and can be measured by the method described in the [Examples] section below. A molecular orientation degree (SOR) of 1.0 signifies perfect isotropy, and a molecular orientation degree (SOR) of 1.0 or close to it is preferable.

[0077] The degree of molecular orientation (SOR) of liquid crystal polymer films can be measured using a microwave molecular orientation analyzer. The sample is inserted into a microwave resonant waveguide so that its surface is perpendicular to the direction of microwave propagation, and the electric field intensity (microwave transmission intensity) of the microwaves that have passed through the sample is measured. The m-value (refractive index) is calculated using the following formula. m=(Z0 / Δz)×[1-ν max / ν0] Here, Z0 is the apparatus constant, Δz is the average thickness of the object, and ν max ν0 is the frequency that gives the maximum microwave transmission intensity when the microwave frequency is changed, and ν0 is the frequency that gives the maximum microwave transmission intensity when the average thickness is zero (i.e., when there is no object). When the rotation angle of the object with respect to the direction of microwave vibration is 0° (i.e., when the direction of microwave vibration coincides with the direction in which the molecules of the object are best oriented and which gives the minimum microwave transmission intensity), the m value is defined as m0, and when the rotation angle is 90°, the m value is defined as m 90 The degree of molecular orientation (SOR) can be calculated using the following formula. [Molecular orientation degree (SOR)]=m0 / m 90

[0078] (Heat distortion temperature) The thermal distortion temperature of the liquid crystal polymer film is not particularly limited, but is preferably 180 to 320°C. The lower limit is more preferably 200°C, and the upper limit is more preferably 300°C. The thermal distortion temperature can be measured as follows: A test specimen measuring 5 mm in width and 20 mm in length is cut from a liquid crystal polymer film. Using a thermomechanical analyzer (TMA), a tensile load of 1 g is applied to both ends of the test specimen, and the temperature is increased from room temperature (20-25°C) at a heating rate of 5°C / min until the film breaks. The thermal distortion temperature is the temperature at which rapid expansion (elongation) occurs, and can be determined as the temperature at the intersection of the tangent line of the high-temperature baseline and the tangent line of the low-temperature baseline in the temperature-deformation curve.

[0079] [Method for manufacturing liquid crystal polymer films] The method for producing the liquid crystal polymer film is not particularly limited, and examples include solution casting and extrusion molding, with extrusion molding being preferred. Examples of extrusion molding methods include the T-die method and the inflation method, with inflation molding being preferred.

[0080] In the T-die method, the molten film extruded from the T-die, or the film obtained by cooling the molten film extruded from the T-die, may be subjected to a stretching treatment. The stretching method is not particularly limited and includes uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, and tubular stretching, with simultaneous biaxial stretching and sequential biaxial stretching being preferred. The stretching direction can be the direction of resin flow (also called MD (Machine Direction) or longitudinal direction) and / or the direction perpendicular to the direction of resin flow (also called TD (Transverse Direction) or transverse direction). By performing biaxial stretching in the longitudinal (MD) and transverse (TD) directions using simultaneous biaxial stretching or sequential biaxial stretching, it is possible to easily control the molecular orientation in these two axial directions and obtain isotropic or nearly isotropic liquid crystal polymer films.

[0081] In the inflation method, air is introduced into the interior of a cylindrical molten film extruded from a ring-shaped die, causing the molten film to expand. In this method, stress is applied to the molten film in both the longitudinal (MD) and transverse (TD) directions, enabling biaxial stretching in both directions. By performing biaxial stretching in both directions, the molecular orientation in these two axes can be easily controlled, and an isotropic or nearly isotropic liquid crystal polymer film can be obtained. The stretch ratio in the longitudinal direction (MD) can be adjusted by the drawdown ratio, and the stretch ratio in the transverse direction (TD) can be adjusted by the blow ratio. The stretch ratio in the longitudinal direction (MD) is not particularly limited, but is preferably 1.1 to 10.0 times. The lower limit is more preferably 1.2 times, even more preferably 1.5 times, particularly preferably 1.8 times, and most preferably 2.0 times. The upper limit is more preferably 8.0 times, even more preferably 7.0 times, even more preferably 6.0 times, particularly preferably 5.0 times, and most preferably 3.0 times. The stretch ratio in the lateral direction (TD) is not particularly limited, but is preferably 1.5 to 20.0 times. The lower limit is more preferably 2.0 times, even more preferably 2.5 times, even more preferably 3.0 times, even more preferably 3.5 times, particularly preferably 4.0 times, and most preferably 4.5 times. The upper limit is more preferably 15.0 times, even more preferably 12.0 times, even more preferably 10.0 times, even more preferably 8.0 times, even more preferably 7.0 times, particularly preferably 6.0 times, and most preferably 5.0 times.

[0082] Liquid crystal polymer films produced by methods such as the T-die method and the inflation method may be subjected to further post-treatment, such as heat treatment, as needed. Let Tm [°C] be the melting point of the thermoplastic liquid crystal polymer film. By performing an annealing treatment on the liquid crystal polymer film, which involves heating it at a temperature of approximately Tm+5 [°C] to Tm+15 [°C] for 20 seconds to 5 minutes, the orientation can be relaxed. After such annealing treatment, the liquid crystal polymer film exhibits relaxed stretching in both MD and TD directions, and its mechanical properties, such as elastic modulus, can become isotropic. Annealing can be performed, if necessary, with the liquid crystal polymer film supported by a support such as metal foil (e.g., aluminum foil).

[0083] [Wiring board] The wiring board of this disclosure is manufactured using the metal-clad laminate of this disclosure described above, and may include an insulating layer made of a liquid crystal polymer film and a wiring layer (also referred to as a circuit) including wiring, etc. A wiring board can be manufactured by forming a predetermined wiring layer (circuit) using the metal layer on the outermost surface of the metal-clad laminate shown in the first or second embodiment in Figure 1. Methods for forming wiring layers (circuits) with a predetermined pattern include subtractive methods, which involve etching a metal layer, and MSAP (Modified Semi Additive Process) methods, which form wiring by plating on a metal layer. The resulting wiring substrate can be further multilayered by repeating the process of laminating metal-clad laminates and forming wiring layers (circuits) with a predetermined pattern one or more times. [Examples]

[0084] Examples and comparative examples of the present invention will be described below. Unless otherwise specified, the length and width directions of samples obtained from pre-laminates and metal-clad laminates are the direction of travel (MD: Machine Direction) and the width direction (TD: Transverse Direction) in the roll-to-roll process, respectively.

[0085] [Evaluation items and evaluation methods] The evaluation items and methods are as follows: (Melting point (Tm) of liquid crystal polymer film) The melting point (Tm) of the liquid crystal polymer film was measured using a differential scanning calorimeter (TA Instruments "DSC Q2000"). A 10 mg sample, cut from a liquid crystal polymer film, was placed in an aluminum pan and set in the apparatus described above. After purging with nitrogen for more than 30 minutes, the temperature was increased from room temperature (20-25°C) to 400°C at a rate of 10°C / min in a 10 ml / min nitrogen stream, held for 5 minutes, and then cooled to 50°C at a rate of 10°C / min (first scan). The DSC curve was then measured. The endothermic peak temperature obtained from this DSC curve was defined as the melting point (Tm) of the liquid crystal polymer film. (Thickness) The thickness of the liquid crystal polymer film was measured using a micrometer (MDC-25MX, manufactured by Mitutoyo Corporation). A test specimen measuring 30 mm in width and 10 mm in length was cut from a liquid crystal polymer film. The thickness was measured at five locations: near one short side of the specimen, near the other short side, along the center line parallel to the length, midway between one short side and the center line parallel to the length, and midway between the other short side and the center line parallel to the length. The arithmetic mean of these measurements was used as the data. Note that the vicinity of the short sides is within 3 mm of the short side.

[0086] (Height of the ten-point region (S10z)) A test piece measuring 30 cm in width and 10 cm in length was cut from copper foil. Under conditions of 23-25°C, the surface roughness of the copper foil in contact with the liquid crystal polymer film was measured using a 3D measuring laser microscope (OLYMPUS "LEXT® OLS5100") in accordance with ISO 25178-71 (2017). The objective lens magnification was set to 100x, and the laser microscope magnification was set to 8x. Each measurement point measured an area of ​​approximately 16 μm x 16 μm (area: approximately 256 μm²). 2 Measurements were taken using the provided analysis software, and the height of the ten-point region (S10z) was determined. The cutoff value was set to 8 μm. The height of the ten-point region (S10z) was measured at five locations: near one short side of the test specimen, near the other short side, along the center line parallel to the length direction, midway between one short side and the center line parallel to the length direction, and midway between the other short side and the center line parallel to the length direction. The arithmetic mean of these measurements was used as the data. Note that the vicinity of the short sides is within 30 mm of the short side.

[0087] (Delamination strength) Two test pieces, 3 mm wide and 100 mm long, were cut from a pre-laminate, a double-sided copper-clad laminate (double-sided CCL), or a single-sided copper-clad laminate (single-sided CCL). The first test specimen was for measuring the delamination strength of the MD (Machine Direction), with its length aligned to the direction of travel (MD) in the roll-to-roll process. The second test specimen was for measuring the delamination strength of the TD, with the length direction being the width direction (TD (Transverse Direction)) in the roll-to-roll process. For each test specimen, the delamination strength was measured in accordance with JIS C 6471:1995 using an electric measuring stand with a 90° delamination test slide table manufactured by IMADA Corporation and their "Digital Force Gauge ZTS-5N" as tensile testing equipment. The test specimen was fixed to a flat plate (stainless steel panel) with double-sided adhesive tape so that one copper foil contained in the test specimen became the uppermost layer. One short side of the uppermost copper foil was pulled perpendicular to the surface of the liquid crystal polymer film directly beneath it, and the tensile stress [N / mm] was measured at 0.1-second intervals when the specimen was peeled at a peeling speed of 50 mm / min. After each second, the average value of the 10 data points obtained in that second (average value for the second) was calculated, and the relationship between time and stress was graphed. As the delamination strength, the minimum value of the tensile stress in the center of a 100 mm long test specimen (within a range of ±20 mm from the center in the longitudinal direction of the test specimen) was determined. For the pre-laminate of the double-sided laminated structure and the double-sided copper-clad laminate (double-sided CCL), measurements were performed on each of the two copper foils contained in the test piece, and the minimum value of the peel strength of the two copper foils was adopted as the data.

[0088] (Number of voids) The copper foil contained in a double-sided copper-clad laminate (double-sided CCL) or a single-sided copper-clad laminate (single-sided CCL) was etched off, and a test piece measuring 540 mm in width and 200 mm in length was cut from the resulting liquid crystal polymer film. A microscope (OLYMPUS MX63L) was used to capture camera images using transmitted light from a light source. The magnification of the microscope's objective lens was set to 5x. The illuminance of the inspection light on the measurement surface was set to 73 klx, and the exposure speed of the microscope camera was set to a value corresponding to the film thickness (1 / 1250 [sec] for a film thickness of 25 μm; 1 / 1000 [sec] for a film thickness of 38 μm; 1 / 640 [sec] for a film thickness of 50 μm; 1 / 500 [sec] for a film thickness of 75 μm; 1 / 320 [sec] for a film thickness of 100 μm). Image processing to remove the background was performed on the captured camera image, and then offset image correction was applied so that the brightness of the background became a grayscale value of 128 for a grayscale value range of 0 to 255. The voids were observed to be brighter than the overall brightness of the film. The number of voids was determined by counting the number of bright spots with a diameter of 5 μm or more that had a brightness level corresponding to the film thickness (for a film thickness of 25 μm, the grayscale value was 145 or higher; for a film thickness of 38 μm, the grayscale value was 140 or higher; for a film thickness of 50 μm or more, the grayscale value was 135 or higher). Each measurement point is measured in an area of ​​30mm width and 100mm length (area: 3,000mm²). 2 The measurement was performed using ). The number of voids was measured at five locations on the test specimen: near one short side, near the other short side, along the center line parallel to the length, midway between one short side and the center line parallel to the length, and midway between the other short side and the center line parallel to the length. The total value of these measurements (total measurement area: 15,000 mm²) was then calculated.2 The following data was used: The vicinity of the short side was defined as an area within 50 mm of the short side. Furthermore, the stage on which the test specimen was placed was automatically moved to ensure that the five measurement areas did not overlap, and measurements were performed.

[0089] [material] The following materials were prepared. <Copper foil> (Cu1) Copper foil (Fukuda Metal Foil & Powder Industry Co., Ltd. "CF-H9A-DS-HD2", thickness 12 μm, width 540 mm). The surface in contact with the liquid crystal polymer film was a low-roughness surface, and its ten-point region height (S10z) was 1.586 μm.

[0090] <Protective film> (PI1) Polyimide film, "Apical" manufactured by Kaneka Corporation, 125 μm thick, 545 mm wide.

[0091] <Liquid crystal polymer film> (CTZ) Kuraray Co., Ltd.'s "Vecter (registered trademark) CTZ-50", thickness 50 μm, width 535 mm, melting point (Tm): 335℃.

[0092] [Example E1] (First process) (Double Belt Press (DBP) process) The first protective film (PI1), the first copper foil (Cu1), the liquid crystal polymer film (CTZ), the second copper foil (Cu1), and the second protective film (PI1) were continuously supplied to a double belt press device including a pair of endless belts and heat-pressed together. The conveying speed was set to 2.0 m / min. The pair of endless belts were heated to a maximum heating temperature (T max The temperature was set to 330℃ (Tm-5[℃]), and the applied pressure (surface pressure) was set to 6MPa. max [℃]~T max The temperature of -10°C was maintained for 15 seconds. The first and second protective films (PI1) were peeled off to obtain a preliminary laminate (double-sided laminate) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1).

[0093] (Second process) (Roll press (RP) process) The first protective film (PI1), the resulting pre-laminate, and the second protective film (PI1) were continuously supplied to a roll press device including a pair of heated and pressurized rolls (metal rolls) and heat-pressed together. The conveying speed was set to 2.0 m / min.

[0094] A hydraulic roll press was used as the roll press device, which included an upper roll, a lower roll, and two hydraulic cylinders that pressurized one of the rolls.

[0095] As shown in the calculation formula below, the pressure (surface pressure) applied by a pair of heated and pressurized rolls was determined by dividing the weight of the laminate sandwiched between the upper and lower rolls by the effective area of ​​the heated and pressurized rolls. [Surface pressure on the laminate sandwiched between the upper and lower rolls (MPa)] = [Weight on the laminate sandwiched between the upper and lower rolls (N)] / [Effective area of ​​the heated and pressurized roll (m²)] 2 )] / 1,000,000=52478.6 / 0.00218 / 1,000,000=24.1

[0096] The weight of the laminate sandwiched between the upper and lower rolls was calculated by subtracting the weight of the lower roll from the total output of the two hydraulic cylinders. In the case of the roll press machine used in this study, the weight of the laminate sandwiched between the upper and lower rolls was 52478.6N.

[0097] Furthermore, the effective area of ​​the heated and pressurized roll was calculated by pressing one heated and pressurized roll onto pressure-sensitive paper without rotating it, and measuring the width and length of the shape imprinted on the pressure-sensitive paper. In the case of the roll press device used in the [Examples] section, the shape imprinted on the pressure-sensitive paper had a width of 4 mm and a length of 545 mm, and the effective area obtained from the product of these values ​​was 0.00218 m². 2 That was the case.

[0098] The pair of heated and pressurized rolls were set to a surface temperature of 270°C (Tm-65°C) and a pressing force (surface pressure) of 24.1 MPa. The heat-pressure bonding time was 0.12 seconds.

[0099] The five-layer laminate obtained after thermocompression bonding was transported and cooled, and after cooling, the first and second protective films (PI1) were peeled off to obtain a double-sided copper-clad laminate (double-sided CCL) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1). The interlayer delamination strength between the liquid crystal polymer film and the copper foil was measured for the preliminary laminate obtained after the first process and the double-sided copper-clad laminate (double-sided CCL) obtained after the second process. The number of voids in the double-sided copper-clad laminate (double-sided CCL) obtained after the second process was measured. Table 1 shows the main manufacturing conditions and evaluation results. In the examples shown in Table 1, conditions not listed in the table were considered common conditions.

[0100] [Example E2] (First process) (Double Belt Press (DBP) process) The first protective film (PI1), the first copper foil (Cu1), the liquid crystal polymer film (CTZ), and the second protective film (PI1) were continuously supplied to a double belt press device including a pair of endless belts and heat-pressed together. The heat-pressing conditions were the same as those for the first step of Example E1. The first and second protective films (PI1) were peeled off to obtain a preliminary laminate (single-area layer) having a laminated structure of the first copper foil (Cu1) / liquid crystal polymer film (CTZ). I obtained it.

[0101] (Second process) (Roll press (RP) process) The first protective film (PI1), the resulting pre-laminate, and the second protective film (PI1) were continuously supplied to a roll press apparatus including a pair of heated and pressurized rolls (metal rolls) and heat-pressed together. The heat-pressing conditions were the same as those for the second step of Example E1. The four-layer laminate obtained after thermocompression bonding was transported and cooled, and after cooling, the first and second protective films (PI1) were peeled off to obtain a single-sided copper-clad laminate (single-sided CCL) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ). Table 1 shows the main manufacturing conditions and evaluation results.

[0102] [Example E3] (First process) (Double Belt Press (DBP) process) A preliminary laminate (single-area layer) having a laminated structure of the first copper foil (Cu1) / liquid crystal polymer film (CTZ) was obtained in the same manner as in the first step of Example E2.

[0103] (Second process) (Roll press (RP) process) The first protective film (PI1), the resulting pre-laminate, the second copper foil (Cu1), and the second protective film (PI1) were continuously supplied to a roll press apparatus including a pair of heated and pressurized rolls (metal rolls) and heat-pressed. The heat-pressing conditions were the same as those for the second step of Example E1. The five-layer laminate obtained after thermocompression bonding was transported and cooled, and after cooling, the first and second protective films (PI1) were peeled off to obtain a double-sided copper-clad laminate (double-sided CCL) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1). Table 1 shows the main manufacturing conditions and evaluation results.

[0104] [Comparative Example EC1] (First process) (Double Belt Press (DBP) process) The first protective film (PI1), the first copper foil (Cu1), the liquid crystal polymer film (CTZ), the second copper foil (Cu1), and the second protective film (PI1) were continuously supplied to a double belt press device including a pair of endless belts including a pair of heated pressure rolls (metal rolls) and heat-pressed together. The heat-pressing conditions were the same as those for the first step of Example E1. The first and second protective films (PI1) were peeled off to obtain a double-sided copper-clad laminate (double-sided CCL) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1). Table 1 shows the main manufacturing conditions and evaluation results.

[0105] [Comparative Example EC2] (First process) (Double Belt Press (DBP) process) A preliminary laminate (double-sided laminate) having a laminated structure of a first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1) was obtained in the same manner as in the first step of Comparative Example EC1.

[0106] (Second process) (Double Belt Press (DBP) process) The first protective film (PI1), the resulting pre-laminate, and the second protective film (PI1) were continuously supplied to a double-belt press machine including a pair of endless belts and heat-pressed. The heat-pressing conditions were the same as those for the first step of Example E1. The first and second protective films (PI1) were peeled off to obtain a double-sided copper-clad laminate (double-sided CCL) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1). Table 1 shows the main manufacturing conditions and evaluation results.

[0107] [Comparative Example EC3] (First process) (Roll press (RP) process) The first protective film (PI1), the first copper foil (Cu1), the liquid crystal polymer film (CTZ), the second copper foil (Cu1), and the second protective film (PI1) were continuously supplied to a roll press device including a pair of heated and pressurized rolls (metal rolls) and heat-pressed together. The heat-pressing conditions were the same as those for the second step of Example E1. The five-layer laminate obtained after thermocompression bonding was transported and cooled, and after cooling, the first and second protective films (PI1) were peeled off to obtain a double-sided copper-clad laminate (double-sided CCL) having a laminated structure of first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1). Table 1 shows the main manufacturing conditions and evaluation results.

[0108] [Comparative Example: EC4] (First process) (Roll press (RP) process) A preliminary laminate (double-sided laminate) having a laminated structure of a first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1) was obtained in the same manner as in the first step of Comparative Example EC3.

[0109] (Second process) (Heat treatment (HT) process) The resulting pre-laminate was heat-treated at 320°C (Tm-15[°C]) for 15 seconds under no pressure. In this way, a double-sided copper-clad laminate (double-sided CCL) having a laminated structure of a first copper foil (Cu1) / liquid crystal polymer film (CTZ) / second copper foil (Cu1) was obtained. Table 1 shows the main manufacturing conditions and evaluation results.

[0110] [Table 1]

[0111] [Summary of results] The metal foils used in Examples E1-E3 and Comparative Examples EC1-EC4 had a ten-point region height (S10z) of 0-2.3 μm on the surface in contact with the liquid crystal polymer film, indicating low surface roughness.

[0112] In Examples E1 to E3, a liquid crystal polymer film and one or more metal foils were supplied to a double belt press apparatus including a pair of endless belts so that a metal foil was laminated on at least one surface of the liquid crystal polymer film, and a pre-laminate was obtained by heat-pressing. In all of these examples, the pre-laminates obtained, both MD and TD, showed an interlayer peel strength of 0.20 to 5.00 N / mm (0.30 to 5.00 N / mm) between the liquid crystal polymer film and the copper foil.

[0113] In Examples E1 and E2, the obtained pre-laminates were supplied to a roll press apparatus including a pair of heated and pressurized rolls and heat-compressed to produce double-sided copper-clad laminates (double-sided CCL) or single-sided copper-clad laminates (single-sided CCL). In Example E3, the obtained single-area layer structure pre-laminate and copper foil were supplied to a roll press apparatus including a pair of heated and pressurized rolls, and a double-sided copper-clad laminate (double-sided CCL) was manufactured by thermocompression bonding.

[0114] In these examples, the double-sided copper-clad laminates (double-sided CCL) or single-sided copper-clad laminates (single-sided CCL) ultimately obtained all exhibited good interlayer adhesion, with interlayer peel strengths of 0.42 to 5.00 N / mm between the liquid crystal polymer film and the copper foil in both MD and TD configurations. The double-sided copper-clad laminates (double-sided CCL) or single-sided copper-clad laminates (single-sided CCL) ultimately obtained in these examples all have an area of ​​15,000 mm². 2 The number of voids with a diameter of 5 μm or larger per unit area was 0, meaning that no voids with a diameter of 5 μm or larger were present at all.

[0115] In Comparative Example EC1, a liquid crystal polymer film and two metal foils were supplied to a double-belt press machine including a pair of endless belts so that metal foils were laminated on at least one surface of the liquid crystal polymer film, and a double-sided copper-clad laminate (double-sided CCL) was manufactured by heat-pressing them together. In Comparative Example EC2, a liquid crystal polymer film and two metal foils were supplied to a double-belt press machine including a pair of endless belts so that metal foils were laminated on at least one surface of the liquid crystal polymer film, and a pre-laminate was obtained by heat-pressing. Furthermore, the obtained pre-laminate was supplied to a double-belt press machine including a pair of endless belts and heat-pressed to produce a double-sided copper-clad laminate (double-sided CCL). In these comparative examples, the double-sided copper-clad laminates (double-sided CCLs) ultimately obtained, both MD and TD, all exhibited poor interlayer adhesion, with the delamination strength between the liquid crystal polymer film and the copper foil being less than 0.42 N / mm.

[0116] In comparative example EC3, a liquid crystal polymer film and two metal foils were supplied to a roll press device including a pair of heated and compressed rolls so that metal foils were laminated on at least one surface of the liquid crystal polymer film, and a double-sided copper-clad laminate (double-sided CCL) was manufactured by thermocompression bonding. In Comparative Example EC4, a liquid crystal polymer film and two metal foils were supplied to a roll press apparatus including a pair of heated and compressed rolls so that metal foils were laminated on at least one surface of the liquid crystal polymer film, and a pre-laminate was obtained by heat-pressing. Furthermore, the obtained pre-laminate was heat-treated to produce a double-sided copper-clad laminate (double-sided CCL). In these comparative examples, the double-sided copper-clad laminates (double-sided CCLs) ultimately obtained all had an area of ​​15,000 mm². 2 There were over 15,000 voids with a diameter of 5 μm or more per unit area, indicating a large number of voids were observed.

[0117] The present invention is not limited to the embodiments and examples described above, and design modifications can be made as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0118] 1, 2 Metal-clad laminate 11 Insulating layer 12 metal layer 12S Surface of the metal layer in contact with the liquid crystal polymer film LCF Liquid Crystal Polymer Film MF Metal Foil DBPS Double Belt Press Machine EB Endless Belt LB Pre-laminate RPS Roll Press Machine R Heat-pressed roll CCL metal clad laminate

Claims

1. A method for manufacturing a metal-clad laminate, wherein a metal layer is laminated on at least one surface of an insulating layer comprising one or more liquid crystal polymer films containing a thermoplastic liquid crystal polymer, in contact with the liquid crystal polymer film, Step (S1) involves supplying one or more liquid crystal polymer films and one or more metal foils to a double belt press device including a pair of endless belts, and heat-pressing them to produce a pre-laminate in which the metal layers are laminated on at least one surface of the insulating layer including one or more liquid crystal polymer films, A method for manufacturing a metal-clad laminate, comprising the steps of: (S2) supplying the pre-laminate to a roll press device including a pair of heating and pressing rolls and heat-pressing it;

2. In process (S1), the maximum heating temperature (T ｍａｘ ) is such that when the melting point of the liquid crystal polymer film is Tm [°C], the pressure is between Tm - 15 [°C] and Tm + 20 [°C], and the pressure is between 0.5 and 10 MPa, T ｍａｘ [℃] ~ T ｍａｘ A method for manufacturing a metal-clad laminate according to claim 1, wherein thermocompression bonding is performed under the condition that the temperature of -10 [°C] is maintained for 10 to 360 seconds.

3. The method for manufacturing a metal-clad laminate according to claim 1, wherein in step (S2), the heating temperature is Tm-150 [°C] to Tm-10 [°C], where Tm [°C] is the melting point of the liquid crystal polymer film, the pressing force is 10 to 40 MPa, and the heat-compression bonding time is 0.0001 to 5.0 seconds.

4. The method for manufacturing a metal-clad laminate according to claim 1, wherein the pre-laminate has an interlayer peel strength of at least 1 direction between the liquid crystal polymer film and the metal layer, measured in accordance with JIS C 6471:1995, of 0.20 to 5.00 N / mm.

5. The method for manufacturing a metal-clad laminate according to claim 1, wherein the metal-clad laminate has an interlaminar peel strength of at least 1 direction between the liquid crystal polymer film and the metal layer, as measured in accordance with JIS C 6471:1995, of 0.42 to 5.00 N / mm.

6. The method for manufacturing a metal-clad laminate according to claim 1, wherein the metal layer has a ten-point region height (S10z) of the surface in contact with the liquid crystal polymer film, measured in accordance with ISO 25178-71 (2017), which is 0 to 2.30 μm.

7. The aforementioned metal-clad laminate has an area of ​​15,000 mm². ２ A method for manufacturing a metal-clad laminate according to claim 1, wherein the number of voids with a diameter of 5 μm or more per unit area is 0 to 15.

8. The method for producing a metal-clad laminate according to claim 1, wherein the thermoplastic liquid crystal polymer comprises one or more aromatic compounds selected from the group consisting of aromatic polyesters, aromatic polyesteramides, and aromatic polyamides.

9. The method for producing a metal-clad laminate according to claim 1, wherein the thermoplastic liquid crystal polymer includes an aromatic polyester having 4-hydroxybenzoic acid units and / or 6-hydroxy-2-naphthoic acid units.

10. The method for manufacturing a metal-clad laminate according to claim 1, wherein the thickness of the liquid crystal polymer film is 10 to 500 μm, and the thickness of the metal layer is 1 to 200 μm.

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