阅读说明：本技术 覆金属层叠板 (Metal-clad laminated board ) 是由 中岛崇裕 高桥健 小野寺稔 于 2017-03-06 设计创作，主要内容包括：本发明提供热塑性液晶聚合物膜与金属片的覆金属层叠板。其制造方法为通过卷对卷制造在热塑性液晶聚合物膜的至少一个表面上接合有金属片的覆金属层叠板的方法,其中,所述金属片的与热塑性液晶聚合物膜接触的面的十点平均粗糙度(Rz)为5.0μm以下,所述方法至少具备：层叠板准备工序,将所述热塑性液晶聚合物膜与所述金属片接合而得到层叠板；干燥工序,使所述层叠板从满足以下的条件(1)和(2)的干燥区通过：(1)干燥工序的温度为低于所述热塑性液晶聚合物膜的熔点的温度,(2)干燥工序的时间为10秒以上；和热处理工序,在该干燥工序后,使所述层叠板连续地在所述热塑性液晶聚合物膜的熔点以上的温度条件下从加热区通过。(The invention provides a metal-clad laminate of a thermoplastic liquid crystal polymer film and a metal sheet. The manufacturing method is a method for manufacturing a metal-clad laminate in which a metal sheet is bonded to at least one surface of a thermoplastic liquid crystal polymer film by roll-to-roll, wherein the ten-point average roughness (Rz) of the surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is 5.0 [ mu ] m or less, and the method at least comprises: a laminate preparation step of bonding the thermoplastic liquid crystal polymer film to the metal sheet to obtain a laminate; a drying step of passing the laminated sheet through a drying zone satisfying the following conditions (1) and (2): (1) the temperature of the drying step is lower than the melting point of the thermoplastic liquid crystal polymer film, and (2) the time of the drying step is 10 seconds or more; and a heat treatment step of continuously passing the laminated sheet through a heating zone under a temperature condition of not less than the melting point of the thermoplastic liquid crystal polymer film after the drying step.)

1. A metal-clad laminate sheet which is a metal-clad laminate sheet having a thermoplastic liquid crystal polymer film and a metal sheet laminated on at least one surface of the thermoplastic liquid crystal polymer film, wherein,

the metal sheet has a ten-point average roughness Rz of the surface thereof in contact with the thermoplastic liquid crystal polymer film of 5.0 [ mu ] m or less,

the peel strength between the thermoplastic liquid crystal polymer film and the metal sheet is 0.7kN/m or more,

every 1m²The average number of bubbles generated in the area is 20 or less.

2. The metal-clad laminate according to claim 1, wherein a skin layer forming at least one surface of the thermoplastic liquid crystal polymer film has the same molecular orientation as a core layer inside the thermoplastic liquid crystal polymer film.

3. The metal clad laminate of claim 1 or 2, wherein every 1m²The average number of bubbles generated in the area is 20 or less per 1m²Average number of generated bubbles in area by observing surface 10m of metal-clad laminate with camera²And detecting the brightness caused by the reflection of the metal surface from the light source and measuring the brightness by image processing.

4. The metal-clad laminate of claim 1 or 3, wherein the bubbles have a height of 5 to 10 μm and a diameter of 200 to 500 μm.

5. The metal-clad laminate according to claim 1 or 2, wherein a ten-point average roughness Rz of a surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is 2.0 μm or less.

6. The metal-clad laminate of claim 1 or 2, wherein the thermoplastic liquid crystal polymer film has a thickness in the range of 10 to 500 μm.

7. The metal-clad laminate of claim 1 or 2, wherein the thickness of each monolayer of metal sheets is in the range of 6 to 200 μm.

Technical Field

The present invention relates to a method for producing a metal-clad laminate using a film (hereinafter referred to as a "thermoplastic liquid crystal polymer film") containing a thermoplastic polymer (hereinafter referred to as a "thermoplastic liquid crystal polymer") capable of forming an optically anisotropic melt phase.

Background

Metal-clad laminates having a thermoplastic liquid crystal polymer film have been used as materials for circuit boards such as flexible wiring boards and circuit boards for mounting semiconductors, because they have excellent low moisture absorption, heat resistance, chemical resistance and electrical properties derived from the thermoplastic liquid crystal polymer film, and also have excellent dimensional stability.

Patent document 1 (jp 2007-268716 a) discloses a method for producing a laminate by laminating a metal foil and a film made of a liquid crystal polymer forming an optically anisotropic molten phase, wherein in a second step of carrying a roll-transportable laminate formed by thermally pressure-bonding the film and the metal foil in a first step and performing a heating treatment at a temperature 10 ℃ or higher than the melting point of the liquid crystal polymer, the temperature distribution of a carrying region from 200 ℃ to the maximum heating temperature in the temperature raising process of the laminate is set to ± 5 ℃ or less at each position in the width direction, and the following is described: according to this manufacturing method, a laminate with suppressed dimensional variations can be obtained.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2007 & 268716

Disclosure of Invention

Problems to be solved by the invention

In recent years, due to the widespread use of small-sized electronic devices with high performance such as smartphones, parts have been more densely packed, and electronic devices have been increasingly high-performance, and therefore, a metal-clad laminate having excellent adhesion strength between a thermoplastic liquid crystal polymer film and a metal sheet and capable of coping with the increase in frequency of transmission signals (that is, having high-frequency characteristics) has been desired.

Since the high-frequency characteristics, that is, the transmission loss of the metal piece serving as the transmission line depends on the skin effect (surface resistance), the transmission loss of the metal piece having a high roughness and a large Rz, that is, the high-frequency characteristics are increased, depending on the surface shape, in particular, the surface roughness (ten-point average roughness) Rz of the metal piece, while the transmission loss of the metal piece having a low roughness and a small Rz, that is, the high-frequency characteristics are improved, the metal piece having a low roughness and a small surface roughness Rz is desired.

However, when a metal sheet having low roughness is used in order to reduce the resistance of the skin effect and to reduce the transmission loss, the adhesion strength between the metal sheet and the thermoplastic liquid crystal polymer film is insufficient, and therefore, various attempts have been made to satisfy both the transmission loss and the adhesion strength, but the problem has not been sufficiently solved.

Patent document 1 describes that dimensional stability is improved by setting a temperature condition at the time of laminating a liquid crystal polymer film and a metal foil to a specific condition, but does not describe a temperature condition for improving adhesive strength, and does not disclose a technique for improving adhesive strength with a metal foil having low roughness in particular.

The purpose of the present invention is to provide a method for producing a metal-clad laminate, which has high-frequency characteristics, has excellent adhesion strength between a thermoplastic liquid crystal polymer film and a metal sheet, and is inhibited from generating bubbles.

Means for solving the problems

The present inventors have found that, even when a metal sheet having low roughness is used, the adhesion strength between the metal sheet and the thermoplastic liquid crystal polymer film can be improved by forming a laminate by thermally pressing the metal sheet and the thermoplastic liquid crystal polymer film, and then subjecting the laminate to a heat treatment at a temperature equal to or higher than the melting point of the thermoplastic liquid crystal polymer film, but the following problems occur: when the laminate is rapidly raised to a temperature not lower than the melting point of the thermoplastic liquid crystal polymer film, volatile components such as water contained in the film expand and swell due to a rapid temperature change, and appearance defects, that is, bubbles are generated.

As a result of intensive studies for the above-mentioned problems, the present inventors have found that, after a laminate is formed by thermally pressure-bonding a metal sheet and a thermoplastic liquid crystal polymer film, the laminate is subjected to a drying treatment under specific temperature and time conditions, and then subjected to a heat treatment at a temperature equal to or higher than the melting point of the thermoplastic liquid crystal polymer film, thereby suppressing the generation of bubbles and improving the adhesion strength between the thermoplastic liquid crystal polymer film and the metal sheet even with a metal sheet having low roughness, and have completed the present invention.

That is, the present invention is a method for producing a metal-clad laminate in which a metal sheet is bonded to at least one surface of a thermoplastic liquid crystal polymer film, characterized in that,

the method for manufacturing a liquid crystal display device includes the steps of bonding the thermoplastic liquid crystal polymer film to the metal sheet to form a laminate, subjecting the laminate to a drying step that satisfies the following conditions (1) and (2), and then subjecting the laminate to a heat treatment under a temperature condition of not less than the melting point of the thermoplastic liquid crystal polymer film.

(1) The temperature in the drying step is a temperature lower than the melting point of the thermoplastic liquid crystal polymer film.

(2) The time for the drying step is 10 seconds or more.

In the production method of the present invention, the metal sheet is preferably a low-roughness metal sheet, and the ten-point average roughness (Rz) of the surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is preferably 2.0 μm or less.

The present invention may be configured as follows.

[ means 1]

A method for producing a metal-clad laminate by roll-to-roll production of a metal-clad laminate obtained by bonding a metal sheet to at least one surface of a film comprising a thermoplastic polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as "thermoplastic liquid crystal polymer film"), characterized in that,

the metal sheet has a ten-point average roughness (Rz) of a surface in contact with the thermoplastic liquid crystal polymer film of 5.0 μm or less (preferably 2.0 μm or less),

the method at least comprises the following steps:

a laminate preparation step of obtaining a laminate obtained by joining the thermoplastic liquid crystal polymer film and the metal sheet;

a drying step of passing the laminated sheet through a drying zone satisfying the following conditions (1) and (2),

(1) the temperature in the drying step is a temperature lower than the melting point (Tm) of the thermoplastic liquid crystal polymer film (for example, Tm-5 ℃ or lower, preferably Tm-15 ℃ or lower),

(2) the time for the drying step is 10 seconds or longer (preferably about 10 seconds to about 300 seconds, more preferably about 30 seconds to about 200 seconds, and further preferably about 60 seconds to about 150 seconds); and

and a heat treatment step of continuously passing the laminate through a heating zone under a temperature condition of a melting point of the thermoplastic liquid crystal polymer film or higher (preferably, Tm +1 ℃ or higher and lower than Tm +50 ℃, more preferably, Tm +1 ℃ to Tm +30 ℃, and further preferably, Tm +2 ℃ to Tm +20 ℃) after the drying step.

[ means 2]

The method for producing a metal-clad laminate according to mode 1, wherein the ten-point average roughness (Rz) of the surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is 2.0 μm or less (preferably 0.1 to 1.5 μm, more preferably 0.3 to 1.1 μm).

[ means 3]

The method according to mode 1 or 2, wherein a product of a drying temperature (C.) and a drying time (sec) is 1400 to 30000 (preferably 1600 to 30000, more preferably 2000 to 30000).

[ means 4]

The method for producing a metal-clad laminate according to any one of aspects 1 to 3, wherein the rate of temperature rise of the surface of the thermoplastic liquid crystal polymer film in the heat treatment step is 3 to 80 ℃/sec (preferably 5 to 70 ℃/sec).

[ means 5]

The method according to any one of aspects 1 to 4, wherein the temperature in the drying step is 140 to Tm-5 ℃ and the temperature in the heat treatment step is Tm +1 to Tm +30 ℃ assuming that the melting point of the thermoplastic liquid crystal polymer film is Tm (. degree.C.).

[ means 6]

The method for producing a metal-clad laminate according to any one of aspects 1 to 4, wherein the heating temperature in the heat treatment step is Tm +11 ℃ or higher, assuming that the melting point of the thermoplastic liquid crystal polymer film is Tm (° c).

[ means 7]

The method for producing a metal-clad laminate according to any one of aspects 1 to 6, wherein the thermoplastic liquid crystal polymer film has a thickness in the range of 10 to 500 μm (preferably 15 to 200 μm, more preferably 20 to 150 μm), and the metal sheet has a thickness in the range of 6 to 200 μm (preferably 9 to 40 μm, more preferably 10 to 20 μm).

[ means 8]

The method of manufacturing a metal-clad laminate according to any one of aspects 1 to 7, wherein a ratio (unit: μm) of the thickness of the metal sheet to the surface roughness is 200/1 to 50/1 (preferably 150/1 to 50/1).

[ means 9]

A metal-clad laminate sheet which is a metal-clad laminate sheet having a thermoplastic liquid crystal polymer film and a metal sheet laminated on at least one surface of the thermoplastic liquid crystal polymer film, wherein,

the metal sheet has a ten-point average roughness (Rz) of a surface in contact with the thermoplastic liquid crystal polymer film of 5.0 [ mu ] m or less,

the peel strength between the thermoplastic liquid crystal polymer film and the metal sheet is 0.7kN/m or more,

every 1m²The average number of bubbles generated in the area is 20 or less.

[ means 10]

The metal-clad laminate according to mode 9, wherein a ten-point average roughness (Rz) of a surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is 2.0 μm or less.

[ means 11]

The metal-clad laminate according to mode 9 or 10, wherein the thermoplastic liquid crystal polymer film has a thickness in the range of 10 to 500 μm (preferably 15 to 200 μm, more preferably 20 to 150 μm), and the metal sheet has a thickness per one layer in the range of 6 to 200 μm (preferably 9 to 40 μm, more preferably 10 to 20 μm).

Effects of the invention

According to the present invention, a metal-clad laminate having high-frequency characteristics, excellent adhesion strength, and suppressed generation of bubbles can be provided. In addition, such a metal-clad laminate can be efficiently manufactured.

Drawings

Fig. 1 is a sectional view showing the structure of a metal-clad laminate according to an embodiment of the present invention.

Fig. 2 is a schematic view showing the overall configuration of a continuous hot-press apparatus used in the method for manufacturing a metal clad laminate according to an embodiment of the present invention.

Fig. 3 is a sectional view showing the structure of a metal-clad laminate according to another embodiment of the present invention.

Fig. 4 is a schematic view showing the entire configuration of a continuous hot-press apparatus used in a method for manufacturing a metal clad laminate according to another embodiment of the present invention.

Detailed Description

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments.

Fig. 1 is a sectional view showing the structure of a metal-clad laminate according to an embodiment of the present invention.

As shown in fig. 1, a metal-clad laminate 1 of the present embodiment is composed of a thermoplastic liquid crystal polymer film 2 and a metal sheet (hereinafter, also referred to as a metal foil) 3 laminated on one surface of the thermoplastic liquid crystal polymer film 2.

< Metal foil >

The material of the metal foil 3 of the present invention is not particularly limited, and examples thereof include copper, gold, silver, nickel, aluminum, and stainless steel, and copper foil and stainless steel foil are preferably used from the viewpoint of conductivity, workability, cost, and the like. As the copper foil, a copper foil produced by a rolling method or an electrolytic method can be used.

The metal foil 3 may be subjected to chemical treatment such as acid washing, etc. usually. The thickness of the metal foil 3 is preferably in the range of 6 μm to 200 μm, more preferably in the range of 9 μm to 40 μm, and still more preferably in the range of 10 μm to 20 μm.

This is because when the thickness is too small, deformation such as wrinkles may occur in the metal foil 3 in the manufacturing process of the metal-clad laminate 1, and when the thickness is too large, for example, when used as a flexible wiring board, the bending performance may be reduced.

In the present invention, the surface roughness of the metal foil 3 on the surface in contact with the thermoplastic liquid crystal polymer film is small (i.e., low roughness), and the ten-point average roughness Rz may be 5.0 μm or less. Even when the metal-clad laminate has such a low roughness, the metal-clad laminate of the present invention can be produced by a specific production method, and therefore, the adhesion strength can be improved and the generation of bubbles can be suppressed. The ten-point average roughness Rz may be 0.1 μm or more, for example. In particular, when the thickness is 2.0 μm or less, the metal-clad laminate 1 having excellent high-frequency characteristics and excellent adhesion strength can be obtained. In particular, from the viewpoint of the balance between the high-frequency characteristics and the adhesion strength, the thickness is more preferably in the range of 0.1 μm to 1.5 μm, and still more preferably in the range of 0.3 μm to 1.1 μm.

The "surface roughness" as referred to herein means a ten-point average roughness (Rz) of the surface of the metal sheet as measured by a contact surface roughness meter (model: SJ-201, manufactured by Sanfeng corporation), and means a roughness of a surface of the metal foil 3 which is in contact with the thermoplastic liquid crystal polymer film 2.

As a method for measuring the surface roughness, a method of measuring the surface roughness was performed in accordance with JIS B0601: 1994. More specifically, the surface roughness (Rz) is a value obtained by extracting a reference length from a roughness curve in the direction of the average line thereof, and expressing the sum of the average value of the level of the peak top (convex top) from the highest to the fifth highest and the average value of the level of the valley bottom (concave bottom) from the deepest to the fifth lowest in μm, and this surface roughness (Rz) represents a ten-point average roughness.

In addition, from the viewpoint of obtaining good high-frequency characteristics, it is preferable that the thickness of the metal foil and the surface roughness thereof have a predetermined relationship, and for example, the ratio (unit: μm) of the thickness of the metal foil and the surface roughness may be (thickness of metal foil)/(surface roughness) about 200/1 to 50/1, preferably about 150/1 to 50/1.

< thermoplastic liquid crystalline Polymer film >

The raw material of the thermoplastic liquid crystal polymer film of the present invention is not particularly limited. For example, known thermotropic liquid crystal polyesters and thermotropic liquid crystal polyester amides derived from compounds classified into the following exemplified (1) to (4) and derivatives thereof can be cited. However, it goes without saying that there is an appropriate range of combination of the respective raw material compounds in order to obtain a polymer capable of forming an optically anisotropic melt phase.

(1) Aromatic or aliphatic dihydroxy Compound (representative examples refer to Table 1)

[ Table 1]

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

[ Table 2]

(3) Aromatic hydroxycarboxylic acid (representative examples refer to Table 3)

[ Table 3]

(4) Aromatic diamine, aromatic hydroxylamine or aromatic aminocarboxylic acid (see Table 4 for representative examples)

[ Table 4]

Representative examples of the thermoplastic liquid crystal polymers obtained from these raw material compounds include copolymers (a) to (e) having the structural units shown in table 5.

[ Table 5]

In addition, in order to impart desired heat resistance and processability to the film, the thermoplastic liquid crystal polymer used in the present invention preferably has a melting point in the range of about 200 to about 400 ℃, particularly preferably in the range of about 250 to about 350 ℃, but preferably has a lower melting point from the viewpoint of film production.

Therefore, when higher heat resistance or melting point is required, the temporarily obtained film can be subjected to heat treatment, whereby the heat resistance or melting point can be improved to a desired value. An example of the conditions of the heat treatment is described, and even when the melting point of the film obtained temporarily is 283 ℃, if the film is heated at 260 ℃ for 5 hours, the melting point can be made 320 ℃.

The thermoplastic liquid crystal polymer film 2 of the present invention is obtained by extrusion molding the above-mentioned polymer. In this case, any extrusion molding method can be used, but a known T-die film-forming stretching method, a laminate stretching method, an inflation method, and the like are industrially advantageous. In particular, in the inflation method, stress is applied not only in the direction of the mechanical axis (length) of the film (hereinafter referred to as "MD direction") but also in the direction orthogonal thereto (hereinafter referred to as "TD direction"), and therefore a film having a balance between mechanical properties and thermal properties in the MD direction and the TD direction can be obtained.

In the thermoplastic liquid crystal polymer film 2 of the present embodiment, the molecular Orientation degree sor (segment Orientation ratio) in the film longitudinal direction is preferably set to a range of 0.90 or more and less than 1.50, more preferably to a range of 0.95 or more and 1.15 or less, and still more preferably to a range of 0.97 or more and 1.15 or less.

The thermoplastic liquid crystal polymer film 2 having a molecular orientation degree in this range has a good balance of mechanical properties and thermal properties in the MD direction and the TD direction, and is highly practical, and has the advantage of having good isotropy and dimensional stability of the metal-clad laminate 1 used for a circuit substrate, as described above.

When the molecular orientation degree SOR is less than 0.90 or 1.50 or more, the imbalance in the orientation of the liquid crystal polymer molecules is significant, and therefore, the film is hard and is easily cracked in the TD direction or the MD direction. For circuit board applications requiring morphological stability such as no warpage during heating, the molecular orientation degree SOR is preferably in the range of 0.90 or more and less than 1.50 as described above. In particular, when it is necessary to completely eliminate the warp during heating, it is preferably 0.95 to 1.08. Further, by orienting the molecules to be 0.90 or more and 1.08 or less, the film dielectric constant can be made uniform.

The "degree of Molecular Orientation SOR" as used herein is an index of the degree of Molecular Orientation imparted to a segment constituting a molecule, and is a value in consideration of the thickness of an object, unlike the conventional MOR (Molecular Orientation Ratio).

The molecular orientation degree SOR is calculated as follows.

First, the thermoplastic liquid crystal polymer film 2 was inserted into a microwave resonance waveguide so that the film surface was perpendicular to the traveling direction of microwaves using a known microwave molecular orientation degree measuring instrument, and the electric field intensity (microwave transmission intensity) of microwaves transmitted through the film was measured.

Then, based on the measured value, a value of m (referred to as a refractive index) is calculated by the following equation (1).

(math formula 1)

m＝(Zo/△z)×[1-νmax/νo]…(1)

(wherein Zo is a device constant, Δ z is an average thickness of the object, vmax is an oscillation number that provides a maximum microwave transmission intensity when the oscillation number of the microwaves is varied, and vo is an oscillation number that provides a maximum microwave transmission intensity when the average thickness is zero (i.e., when there is no object))

Next, m is set as the value of m when the rotation angle of the object with respect to the vibration direction of the microwave is 0 °, that is, when the vibration direction of the microwave is aligned with the direction in which the molecules of the object are optimally oriented (usually, the longitudinal direction of the extrusion-molded film) and the direction in which the minimum microwave transmission intensity is given₀M is a value of m when the rotation angle is 90 DEG₉₀Through m₀/m₉₀The molecular orientation degree SOR was calculated.

The thickness of the thermoplastic liquid crystal polymer film 2 of the present invention is not particularly limited, but is preferably within a range of 10 to 500. mu.m, and more preferably within a range of 15 to 200. mu.m. When the metal-clad laminate 1 using the thermoplastic liquid crystal polymer film 2 as an electrically insulating material is used as a printed wiring board, the thickness is particularly preferably in the range of 20 to 150 μm, and more preferably in the range of 20 to 50 μm.

This is because, when the film thickness is too thin, the rigidity and strength of the film are reduced, and therefore, when an electronic component is mounted on the obtained printed wiring board, the printed wiring board is deformed by pressurization, and the positional accuracy of the wiring is deteriorated, which causes a problem.

As an electrically insulating material for a main circuit board of a personal computer or the like, a composite of the above thermoplastic liquid crystal polymer film and another electrically insulating material, for example, a glass substrate, may be used. Additives such as lubricants and antioxidants may be incorporated into the film. Additionally, the film may or may not contain fillers.

Next, a method for manufacturing a metal-clad laminate according to an embodiment of the present invention will be described.

The manufacturing method of the present embodiment is a method of manufacturing a metal-clad laminate in which a metal sheet is bonded to at least one surface of a thermoplastic liquid crystal polymer film by roll-to-roll. The metal sheet has a low roughness, and the ten-point average roughness (Rz) of the surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is 5.0 [ mu ] m or less. The method includes a preparation step of obtaining a laminate in which the thermoplastic liquid crystal polymer film and the metal sheet are joined. In this preparation step, a manufactured laminate can be obtained, but it is preferable that a thermoplastic liquid crystal polymer film and a metal foil are bonded (thermocompression bonding) to form a laminate. The method further includes at least a drying step of passing the laminated plate through a drying zone under a predetermined condition and a heat treatment step of passing the laminated plate through a heating zone under a predetermined condition.

The above method may include, for example, a laminate forming step of forming a laminate by bonding (thermocompression bonding) the thermoplastic liquid crystal polymer film 2 and the metal foil 3, a drying step of drying the laminate, and a heat treatment step of heat-treating the laminate.

< Process for Forming laminated plate >

First, a long thermoplastic liquid crystal polymer film 2 is put under tension, a long metal foil 3 is superimposed on one surface of the thermoplastic liquid crystal polymer film 2, and these are laminated by thermocompression bonding between heated rollers.

The "tension state" as used herein means that a tension (for example, 0.12 to 0.28 kg/mm) is applied to the film in the longitudinal direction (stretching direction) of the film²) The state of (1).

Fig. 2 is a schematic view showing the overall configuration of a continuous hot-press apparatus used in the method for manufacturing a metal clad laminate according to an embodiment of the present invention.

The continuous hot press apparatus 10 is an apparatus for manufacturing a single-sided metal-clad laminate in which a metal foil 3 is bonded to one surface of a thermoplastic liquid crystal polymer film 2, and as shown in fig. 2, the continuous hot press apparatus 10 includes an unwinding roll 4 to which a rolled thermoplastic liquid crystal polymer film 2 is attached, an unwinding roll 5 to which a rolled metal foil 3 such as a copper foil is attached, and a heating roll 7 to which the thermoplastic liquid crystal polymer film 2 and the metal foil 3 are bonded by thermocompression bonding to form a laminate 6.

In the case of manufacturing a single-sided metal-clad laminate, for example, a pair of heat-resistant rubber rollers 8 and a heating metal roller 9 (both roller surfaces have a hardness of 80 degrees or more) can be used as the heating roller 7. The heat-resistant rubber roller 8 and the metal roller 9 are preferably arranged such that the heat-resistant rubber roller 8 is arranged on the thermoplastic liquid crystal polymer film 2 side and the heating metal roller 9 is arranged on the metal foil 3 side.

The heat-resistant rubber roller 8 used for producing the single-sided metal-clad laminated sheet preferably has a hardness of 80 degrees or more, more preferably 80 to 95 degrees, on the surface thereof, as measured by a spring type hardness tester a according to JIS K6301. In this case, if the roll surface is too soft, the pressure during thermocompression bonding is insufficient, and the adhesive strength of the laminated sheet 6 is insufficient. Further, if the roll surface is too hard, a local linear pressure acts between the heat-resistant rubber roll 8 and the heating metal roll 9, and the appearance of the laminated plate 6 may be deteriorated. The rubber having an angle of 80 degrees or more can be obtained by adding a vulcanizing agent, a vulcanization accelerator such as an alkali substance, or the like to a synthetic rubber or a natural rubber such as a silicone rubber or a fluorine rubber.

Then, as shown in fig. 1, the thermoplastic liquid crystal polymer film 2 and the metal foil 3 are conveyed in a state of being overlapped in the film longitudinal direction, and are supplied between a pair of heat-resistant rubber rollers 8 and a heating metal roller 9, and the thermoplastic liquid crystal polymer film 2 and the metal foil 3 are laminated by thermocompression bonding.

As the conditions for thermocompression bonding, the temperature of the heating roller is preferably in the range of-40 ℃ to-10 ℃ from the viewpoint of suppressing the stretching of the film, and the pressure is preferably 90kg/cm from the viewpoint of smoothing the surface²～250kg/cm²The pressing time is preferably in the range of 0.1 to 1.5 seconds from the viewpoint of improving the adhesion strength by heating the metal foil 3 side.

< drying Process >

Subsequently, the obtained laminated plate 6 is subjected to a drying treatment. As shown in fig. 2, the continuous hot press apparatus 10 includes a nip roller 11 for conveying the laminated sheet 6, a drying unit 16 for drying the laminated sheet 6, a heating unit 17 for heating, and a winding roller 13 for winding the metal-clad laminated sheet 1 after the heating.

The drying unit 16 is not particularly limited as long as the laminated plate 6 can be dried under the drying conditions of the present invention, and for example, a hot air type heating furnace, a hot air circulation dryer, a hot roll, a ceramic heater, a heat treatment apparatus using IR (far infrared ray), and a method using the above apparatuses in combination can be used. In addition, from the viewpoint of preventing oxidation of the surface of the metal foil 3, it is preferable to perform the heat treatment in an inert atmosphere using nitrogen gas and oxygen concentration of 0.1% or less after heating.

Here, the present invention is characterized in that when the melting point of the thermoplastic liquid crystal polymer film 2 is Tm (deg.c), the drying temperature is lower than Tm (deg.c), and the drying time is 10 seconds or longer.

When the bonding surface of the metal foil has low roughness, it is necessary to perform heat treatment of the thermoplastic liquid crystal polymer film at a temperature equal to or higher than the melting point thereof as described below in order to improve the adhesion between the metal foil and the thermoplastic liquid crystal polymer film. However, the metal-clad laminate obtained in this way may have a problem with bubbles generated in the heat treatment step. The drying treatment under the above conditions may be performed to remove volatile components present in the thermoplastic liquid crystal polymer film that cause bubbles while suppressing the generation of bubbles, and therefore, the generation of bubbles can be suppressed in the subsequent heat treatment step.

The drying temperature in the present invention is not particularly limited as long as it is lower than the melting point (Tm ℃) of the thermoplastic liquid crystal polymer film, and since the effect of removing volatile components in the film becomes more remarkable by the molecular motion of the thermoplastic liquid crystal polymer film caused by heating, it is preferable that the drying temperature is high under the condition lower than the melting point (Tm ℃). The drying temperature is preferably in the range of 100 ℃ to less than Tm ℃, more preferably 140 ℃ to Tm-5 ℃, and still more preferably 200 ℃ to Tm-15 ℃. The drying temperature may be set to a range of Tm-180 ℃ or higher and lower than Tm ℃, preferably Tm-140 ℃ or higher and Tm-5 ℃ or lower, and more preferably Tm-85 ℃ or higher and Tm-15 ℃ or lower. By setting the drying treatment temperature in this range, volatile gas derived from the thermoplastic liquid crystal polymer film can be gradually released without being rapidly generated, and bubbles can be suppressed even in the subsequent heat treatment step. The drying temperature in the present invention means a temperature of the surface of the thermoplastic liquid crystal polymer film in the drying step.

In addition, as for the drying treatment time, the longer the drying time, the more remarkable the effect of removing volatile components containing moisture in the film becomes, and from the viewpoint of production efficiency, it is preferably 10 seconds to 300 seconds, more preferably 30 seconds to 200 seconds, and further preferably 60 seconds to 150 seconds.

For example, from the viewpoint of industrially advantageously promoting the effect of removing volatile components, the product of the drying temperature (DEG C) and the drying time (sec) may be about 1400 to 30000. The product may be preferably 1600 or more, and may be particularly preferably 2000 or more.

< Heat treatment Process >

The heat treatment unit 17 is not particularly limited as long as the laminate 6 can be heat-treated at a temperature equal to or higher than the melting point of the thermoplastic liquid crystal polymer film 2, and for example, a hot air type heat treatment furnace, a hot air circulation dryer, a hot roll, a ceramic heater, a heat treatment apparatus using IR (far infrared ray), and a method using the above apparatuses in combination can be used. In addition, from the viewpoint of preventing oxidation of the surface of the metal foil 3, it is preferable to perform the heat treatment in an inert atmosphere using nitrogen gas and oxygen concentration of 0.1% or less after heating. In addition, the heat treatment process may be performed using the same heating furnace immediately after the drying process. In this case, in order to facilitate heat control, the drying step and the heat treatment step may be performed using a heat treatment apparatus using IR (far infrared ray).

In the present invention, in the heat treatment performed after the drying treatment, it is important that the heat treatment temperature Ta (deg.c) is higher than the melting point Tm (deg.c) of the thermoplastic liquid crystal polymer film, when the heat treatment temperature is Ta (deg.c). When the heat treatment temperature Ta (c) is lower than the melting point Tm (c) of the thermoplastic liquid crystal polymer film, sufficient adhesion strength cannot be obtained particularly in the case of bonding a metal sheet having low roughness to the thermoplastic liquid crystal polymer film. The heat treatment temperature Ta (c) is preferably a temperature higher by 1 c or more and lower than 50 c, more preferably a temperature higher by 1 c or more and lower than 30 c, and still more preferably a temperature higher by 2 c or more and lower than 20 c than the melting point Tm (c) of the thermoplastic liquid crystal polymer film. From the viewpoint of improving the meltability of the thermoplastic liquid crystal polymer film, the heat treatment temperature Ta may be Tm +11 ℃ or higher (for example, Tm +11 ℃ or higher and lower than Tm +50 ℃).

The heat treatment time is preferably 1 second to 10 minutes, more preferably 5 seconds to 8 minutes, still more preferably 8 seconds to 5 minutes, and particularly preferably 8 seconds to 3 minutes. The heat treatment temperature in the present invention means a temperature of the surface of the thermoplastic liquid crystal polymer film in the heat treatment step.

By applying such a heat treatment to the laminate 6, the adhesion strength with the thermoplastic liquid crystal polymer film can be improved even with a metal foil having low roughness. In particular, the adhesion strength between a metal foil having a surface roughness Rz of 2.0 μm or less and a thermoplastic liquid crystal polymer film, which are excellent in high frequency characteristics, can be improved.

The reason why the adhesion strength between the metal foil having low roughness and the thermoplastic liquid crystal polymer film is improved by the above-mentioned heat treatment is presumed to be as follows. That is, in general, when a thermoplastic liquid crystal polymer film and a metal foil are thermocompression bonded, the surface of the thermoplastic liquid crystal polymer film is melted by heat at the time of thermocompression bonding, and molecular orientation called a skin layer is generated on the surface of the thermoplastic liquid crystal polymer film by pressure at the time of thermocompression bonding. Here, the skin layer is likely to be cracked in one direction as compared with the structure of the core layer which is a layer inside the film, and is also a layer different from the core layer in terms of crystal structure, and therefore it is estimated that the interface portion between the core layer and the skin layer becomes weak, and the skin layer becomes a factor of reducing the adhesion strength between the thermoplastic liquid crystal polymer film and the metal foil.

However, in the present embodiment, since the thermoplastic liquid crystal polymer film 2 and the metal foil 3 are thermally pressed and then subjected to the heat treatment at a temperature equal to or higher than the melting point of the thermoplastic liquid crystal polymer film 2 without applying pressure, it is considered that the orientation of the skin layer formed once disappears (that is, the cause of the decrease in the adhesion strength disappears), and as a result, the adhesion strength is improved.

It is preferable that the heat treatment temperature Ta is set to a temperature higher than the melting point Tm of the thermoplastic liquid crystal polymer film 2, because the effect of eliminating the orientation of the skin layer becomes more remarkable.

The skin layer in the present invention means: the cross section of the metal-clad laminate 1 was polished by a cross section polisher, and then the cross section was etched with a propylamine solution, and a layer having a domain structure different from that of the film core layer, which is a surface structure having a domain structure that is not uniform (different) in the thickness direction, was observed on the surface of the thermoplastic liquid crystal polymer film by using an electron microscope (SEM) in a state where the domain structure was emphasized.

In the present invention, it is important to perform a drying treatment using the conditions of the present invention on the laminate before the above-described heat treatment. By performing the drying treatment under the temperature and time conditions of the present invention before the heat treatment, volatile components contained in the thermoplastic liquid crystal polymer film forming the laminate are gradually removed from the surface or side surface of the film without rapidly expanding, and therefore, the generation of bubbles can be suppressed.

When the drying treatment temperature is lower than the melting point, the thermoplastic liquid crystal polymer film forming the laminate does not melt, and therefore, swelling due to volatile components contained in the film does not occur, and the generation of bubbles is suppressed. In addition, within the range of the drying treatment time of the present invention, volatile components such as moisture can be slowly removed from the surface or side surface of the film. When the drying temperature is set to a temperature equal to or higher than the melting point, the laminate is brought to a temperature equal to or higher than the melting point in substantially less than 10 seconds. When the laminate is heated to a temperature of the melting point or higher for 2 to 3 seconds, for example, the thermoplastic liquid crystal polymer film melts without removing volatile components in the film from the film, and therefore the volatile components in the film expand and bubbles are generated in the film.

By performing the drying treatment under the conditions of the present invention, even when the temperature is rapidly raised in order to improve the adhesiveness between the thermoplastic liquid crystal polymer film and the metal foil in the subsequent heat treatment step (for example, the temperature raising rate of the surface of the thermoplastic liquid crystal polymer film is 3 to 80 ℃/sec, preferably 5 to 70 ℃/sec), the generation of bubbles in the film can be suppressed.

In the present invention, in the production of the double-sided metal-clad laminate, the metal sheets may be bonded to both sides of the thermoplastic liquid crystal polymer film, and then the drying treatment and the subsequent heat treatment of the present invention may be performed, or the metal sheets may be bonded to one side of the thermoplastic liquid crystal polymer film, and then the drying treatment of the present invention may be performed to form a single-sided metal-clad laminate, and then the metal sheets may be bonded to the side (film side) of the single-sided metal-clad laminate on which the metal sheets are not bonded, and the heat treatment of the present invention may be performed.

The above embodiment may be modified as follows.

In the above embodiment, the metal-clad laminate 1 in which the metal foil 3 is bonded to one surface of the thermoplastic liquid crystal polymer film 2 was described as an example, but the present invention can also be applied to the metal-clad laminate 1 in which the metal foil 3 is bonded to both surfaces of the thermoplastic liquid crystal polymer film 2 as shown in fig. 3. That is, the present invention can be applied to a metal-clad laminate in which a metal foil 3 is bonded to at least one surface of a thermoplastic liquid crystal polymer film 2.

In this case, as shown in fig. 4, the continuous hot press apparatus 30 further including the unwinding roll 5 to which the metal foil 3 such as a copper foil in a rolled shape is attached (that is, including 2 unwinding rolls 5) is used in the continuous hot press apparatus 10 shown in fig. 2.

Then, as in the case of the above-described embodiment, first, the long thermoplastic liquid crystal polymer film 2 is put in tension, the long metal foils 3 are stacked on both surfaces of the thermoplastic liquid crystal polymer film 2, and they are laminated by pressure-bonding between the heating rollers 7 to produce the laminated plate 15, and then, the drying treatment and the heat treatment of the present invention are performed on the laminated plate 15 thus obtained to produce the metal-clad laminated plate 20.

Next, a metal-clad laminate according to an embodiment of the present invention will be described.

The metal-clad laminate of the present embodiment is a metal-clad laminate having a thermoplastic liquid crystal polymer film and a metal sheet laminated on at least one surface of the thermoplastic liquid crystal polymer film, and has good interlayer adhesion and suppressed generation of bubbles in the metal-clad laminate, although the ten-point average roughness (Rz) of the surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is 5.0 μm or less from the viewpoint of making good high-frequency characteristics.

The peel strength between the thermoplastic liquid crystal polymer film and the metal sheet bonded to the thermoplastic liquid crystal polymer film is, for example, 0.7kN/m or more (for example, 0.7 to 2kN/m), preferably 0.8kN/m or more, and more preferably 0.9kN/m or more, because of good interlayer adhesiveness. The peel strength is a value measured by the method described in the examples described below.

In addition, even in the case of heating at the melting point or more of the liquid crystal polymer film in order to improve the adhesiveness, the generation of bubbles can be suppressed, and therefore, the thickness per 1m can be reduced²The average number of bubbles generated in the area is 20 or less. The average number of generated bubbles is preferably 10 or less, and more preferably 5 or less. The bubbles can be determined by the bulge (about 5 to 10 μm in height and 200 to 500 μm in diameter) of the surface of the laminated plate, and the number of independent bubbles can be determined by the number of individual bubbles. The average number of bubbles generated was measured by measuring 10m of the membrane area²The number of generated bubbles in (1) m²The average conversion value generated in the membrane area was determined.

The liquid crystal polymer film and the metal sheet, after being laminated, each independently have the characteristics described in the liquid crystal polymer film and the metal foil. For example, the ten-point average roughness (Rz) of the surface of the metal sheet in contact with the thermoplastic liquid crystal polymer film is preferably 2.0 μm or less. The thickness of the thermoplastic liquid crystal polymer film may be in the range of 20 to 150 μm, and the thickness of each single layer of the metal sheet may be in the range of 6 to 200 μm.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples at all. The copper-clad laminates in examples and comparative examples were evaluated by the following methods.

< evaluation of air bubbles >

For the surface (10 m) of the metal-clad laminate after heat treatment²) The number of bubbles was measured by detecting the brightness caused by reflection from the film surface of the light source with a camera (LSC-6000 manufactured by MEC corporation) provided on the liquid crystal polymer film side, and performing image processing. In the case of a double-sided metal-clad laminate, the number of bubbles can be measured by detecting the brightness caused by reflection from the metal surface of the light source by a camera provided on the side of either metal layer, and performing image processing. Calculating the number of bubbles per 1m²The average number of generated bubbles in the membrane area.

< evaluation of adhesion Strength >

Subsequently, a peel test piece having a width of 1.0cm was prepared from each of the metal-clad laminates prepared, the thermoplastic liquid crystal polymer film layer of the test piece was fixed to a flat plate with a double-sided adhesive tape, and the strength (kN/m) at the time of peeling the metal foil at a speed of 50 mm/min was measured by a 180 ° method in accordance with JIS C5016.

In addition, from the viewpoint of bending resistance and the like, a peel strength of 0.7kN/m or more is required, and therefore, a case having a strength of 0.7kN/m or more is judged to be good in adhesive strength, and a case having a strength of less than 0.7kN/m is judged to be poor. The above results are shown in table 6.

< measurement of Transmission loss >

Next, the transmission loss of each of the metal clad laminates thus produced was measured. More specifically, a microwave network analyzer [ manufactured by Agilent corporation, model: 8722ES ] and a probe (manufactured by Cascade Microtech Co., Ltd., model: ACP40-250) were measured at a measuring frequency of 40 GHz.

[ reference example 1]

(1) A thermoplastic liquid crystalline polymer film 2 having a thickness of 50 μm was obtained by heating and kneading a liquid crystalline polyester comprising 27 mol% of 6-hydroxy-2-naphthoic acid units and 73 mol% of p-hydroxybenzoic acid units at 280 to 300 ℃ using a single-shaft extruder, and extruding the mixture from a blow die having a diameter of 40mm and a slit interval of 0.6 mm. The film had a melting point Tm of 282 ℃ and a heat distortion temperature Tdef of 230 ℃.

[ example 1]

Using the thermoplastic liquid-crystalline polymer film 2 obtained in reference example 1 and an electrolytic copper foil (ten point average roughness (Rz): 0.9 μm) having a thickness of 12 μm as a metal sheet 3, as shown in FIG. 2, a resin-coated metal roll (Super-Tempex: manufactured by RIBORON MACHI, resin thickness 1.7cm) was used as a roll 8 which was brought into contact with the thermoplastic liquid-crystalline polymer film 2. The thermoplastic liquid crystal polymer film 2 was disposed on the resin-coated metal roll 8 side, and the electrolytic copper foil was disposed on the opposite side. A metal roll 9 and a resin-coated metal roll 8 each having a diameter of 40cm were used. The surface temperature of the metal roller 9 is set to a temperature 20 ℃ lower than the melting point of the thermoplastic liquid crystal polymer film 2. The pressure applied between the rolls to the thermoplastic liquid crystal polymer film 2 and the electrolytic copper foil 3 was 120kg/cm in terms of surface pressure²The thermoplastic liquid crystal polymer film 2 is temporarily bonded to the resin-coated metal roll 8 under the above-described conditions, and then the electrolytic copper foil 3 is bonded to the film 2. Then, both are introduced between the metal roller 9 and the resin-coated metal roller 8, and are joined by pressure bonding, thereby obtaining a laminated sheet 6. The produced laminated sheet 6 was subjected to a heating treatment in an IR furnace having a length of 5m in the line direction. At this time, the temperature distribution of the heating zone in the IR furnace is divided, and the treatment is performed in the drying zone 16 and the heat treatment zone 17. The temperature of the drying zone 16 was set to 140 ℃ which is a temperature lower than the melting point of the thermoplastic liquid crystal polymer film 2, so that any point of the laminate was passed through the drying zone in the IR heating furnace for 15 seconds. In this case, the drying treatment time was 15 seconds. After the laminate was dried in the drying zone 16, the temperature of the heat treatment zone was set to 300 ℃ (temperature rise rate: about 20 ℃/sec) which is a temperature equal to or higher than the melting point of the thermoplastic liquid crystal polymer film 2, and the laminate was heat-treated so as to pass through the heat treatment zone 17 for 30 seconds, thereby producing a metal-clad laminate 1. The results are shown in table 6.

In examples 2 to 9, the drying temperature and the drying time in the drying zone 16 in example 1 were set as shown in table 6, and the metal-clad laminate 1 was produced.

Comparative example 1

A metal-clad laminate 1 was produced in the same manner as in example 3, except that the drying temperature in the drying zone 16 was set to 285 ℃. The results are shown in table 6.

Comparative example 2

After the laminated plate 6 was produced in the same manner as in example 1, the heat treatment of the laminated plate was carried out by providing only the heat treatment zone without providing the drying zone when the heat treatment was carried out in the IR heating furnace. At this time, the temperature of the heat treatment zone was set to 300 ℃ which is a temperature equal to or higher than the melting point of the thermoplastic liquid crystal polymer film, and the temperature was set so as to pass through the heat treatment zone for 30 seconds. In this case, the laminate is heated at about 60 ℃/sec to a set temperature of 300 ℃, and the residence time of the laminate at a temperature lower than the melting point of the thermoplastic liquid crystal polymer film is about 5 seconds. The results are shown in table 6.

Comparative example 3

A metal-clad laminate was produced in the same manner as in example 1, except that the drying time was set to 3 seconds. The results are shown in table 6.

Comparative example 4

A metal-clad laminate was produced in the same manner as in example 4, except that the heat treatment temperature was set to 280 ℃. The results are shown in table 6.

Comparative example 5

After the laminated plate 6 was produced in the same manner as in example 3, the heat treatment of the laminated plate was carried out by providing only the drying treatment zone without providing the heat treatment zone when the heat treatment was carried out in the IR heating furnace. At this time, the temperature and time of the drying treatment zone were set in the same manner as in example 3.

The results are shown in table 6.

In examples 1 to 9, although the film was laminated on a copper foil having a low roughness of Rz 0.9 μm, which was difficult to improve the adhesion strength to the thermoplastic liquid crystal polymer film in the past, no bubbles were generated, and a good adhesion strength and a low transmission loss were obtained, i.e., good high-frequency characteristics were obtained.

In comparative example 1, the drying temperature was set to be not less than the melting point of the thermoplastic liquid crystal polymer film, and therefore, bubbles were generated due to a rapid temperature rise, resulting in poor appearance, and the film was broken due to the generation of bubbles, resulting in poor adhesion strength (less than 0.4kN/m), and further, it was difficult to measure the transmission loss.

In comparative example 2, since the heat treatment step was performed without performing the drying step, the laminate was rapidly heated, and the film was broken due to the generation of bubbles, as in comparative example 1, and the appearance and the adhesion strength were poor (less than 0.4kN/m), and it was difficult to measure the transmission loss due to bubbles.

In comparative example 3, the time for the drying step was 3 seconds and was short, and therefore, the film was broken due to the generation of bubbles, and the appearance and the adhesion strength were poor (less than 0.4kN/m), and it was difficult to measure the transmission loss due to the bubbles.

In comparative example 4, although no bubble was observed due to the drying step, the adhesion strength was poor (less than 0.4kN/m) because the temperature of the heat treatment was lower than the melting point.

In comparative example 5, since the heat treatment step after the drying step was not performed, the adhesion strength was poor (less than 0.4 kN/m).

Industrial applicability

As described above, the present invention can efficiently produce a metal clad laminate using a thermoplastic liquid crystal polymer film, and the metal clad laminate has excellent high-frequency characteristics, and therefore can be advantageously used as a circuit board material, and particularly as a high-frequency circuit board material for use in a microwave millimeter wave antenna and a board material for use in a vehicle radar using microwave millimeter waves.

As described above, the preferred embodiments of the present invention have been described, but various additions, modifications, and deletions can be made within the scope of the present invention, and such embodiments are also included in the scope of the present invention.

Description of the reference symbols

1-clad metal laminated plate

2 thermoplastic liquid crystalline Polymer films

3 Metal foil (Metal sheet)

4 uncoiling roller

5 uncoiling roller

6 laminated plate

7 heating roller

8 Heat-resistant rubber roller

9 heating metal roller

10 continuous hot-pressing device

11 nip roll

16 drying treatment unit, drying zone

17 Heat treatment Unit, Heat treatment zone

13 winding roller

15 laminated plate

20-metal clad laminate

30 continuous hot-pressing device