Laminate and metal-clad laminate having said laminate

Abstract

Provided is a metal-clad laminate (for example, copper-clad laminate (CCL) in which curling is suppressed and which excels in adhesiveness (adhesion) between a base material film (laminated body) and a metal film and dimensional stability while having good electrical properties (dielectric properties) compatible with 5G.　Also provided is a laminated body for a printed wiring board, which is used to form the metal-clad laminate.　This laminated body comprises: a low-CTE resin film having a coefficient of linear thermal expansion (CTE) of 50 ppm / °C or less; and a high-CTE resin film having a coefficient of linear thermal expansion (CTE) of greater than 50 ppm / °C and laminated on both sides of the low-CTE resin film, wherein the low-CTE resin film does not have a melting point at 300°C or less, the low-CTE resin film does not melt at a temperature obtained by adding 30°C to the melting point of the high-CTE resin film, the high-CTE resin film has a melting point of 250°C or higher, and the high-CTE resin film has a tensile elongation at break in the machine direction (MD direction) of 400% or less.

Description

[Technical Field]

[0001] The present invention relates to a laminate and a metal-clad laminate having the laminate. [Background technology]

[0002] In recent years, as communication speeds and capacity have increased in communication devices such as smartphones, the circuit boards used in these devices are required to have low loss in electrical signals, finer pitch circuit patterns, and more precise and fine circuit formation. Metal-clad laminates, which are the main material of circuit boards, are metal-clad laminates (e.g., copper-clad laminates (CCL)) in which a metal film is laminated on the surface of a base film made of insulating resin, and the like, are also required to have performance similar to that of the above-mentioned circuit boards. Various improved metal-clad laminates and laminates for use in the metal-clad laminates have been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-75030 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, with the full-scale introduction of next-generation mobile communication systems such as 5G, there is a demand for metal-clad laminates that use substrate films made of low-dielectric materials. However, since many low-dielectric substrate films have a large CTE, it has been found that when a metal-clad laminate is formed using a low-dielectric substrate film, the film shrinks significantly, resulting in poor dimensional stability of the metal-clad laminate and problems such as deformation and curling of the metal-clad laminate.On the other hand, even if dimensional stability and curling due to film shrinkage are not a problem, it has been found that the adhesion (adhesion) between the substrate film and the metal film may be poor. For example, the copper-clad laminate (CCL) described in Patent Document 1 above was not sufficient from the viewpoint of providing a copper-clad laminate (CCL) that has good electrical properties (dielectric properties) compatible with 5G, excellent adhesion (tightness) between the substrate film and the metal film, excellent dimensional stability, and suppressed curling. Furthermore, since many substrate films with low CTEs, which are used to reduce film shrinkage and improve dimensional stability, have poor dielectric properties, forming a metal-clad laminate using a low-CTE substrate film creates the problem of not being able to obtain a metal-clad laminate with excellent dielectric properties.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a metal-clad laminate (e.g., a copper-clad laminate (CCL)) that has good electrical properties (dielectric properties) compatible with 5G, excellent adhesion (tightness) between the substrate film (laminate) and the metal film, excellent dimensional stability, and suppressed curling. Another object of the present invention is to provide a laminate for a printed wiring board, which is used to form the metal-clad laminate. [Means for solving the problem]

[0006] As a result of extensive research into solving the above-mentioned problems, the inventors have discovered that for a laminate having a resin film with a high linear thermal expansion (CTE) on both sides of a resin film with a low linear thermal expansion (CTE), by specifying the melting points of each resin film and specifying the longitudinal (MD) tensile break elongation of the resin film with a high linear thermal expansion (CTE), a laminate that can solve the above-mentioned problems can be provided, and have completed the present invention.

[0007] The present invention includes the following aspects. [1] A low-CTE resin film having a coefficient of linear thermal expansion (CTE) of 50 ppm / °C or less; A laminate obtained by laminating a high-CTE resin film having a coefficient of linear thermal expansion (CTE) of more than 50 ppm / °C on both sides of the low-CTE resin film, The low CTE resin film has a melting point of not more than 300°C, the low CTE resin film does not melt at a temperature that is 30°C above the melting point of the high CTE resin film; The high CTE resin film exhibits a melting point of 250°C or higher, A laminate in which the high CTE resin film has a tensile elongation at break in the machine direction (MD) of 400% or less. [2] The laminate according to [1], wherein the high CTE resin film has a relative dielectric constant of 3.5 or less and a dielectric loss tangent of 0.008 or less. [3] The laminate according to [1] or [2], wherein the high CTE resin film has a water absorption rate of 1% or less. [4] The laminate according to any one of [1] to [3], wherein the low CTE resin film has a water absorption rate of 2.5% or less. [5] The laminate according to any one of [1] to [4], wherein the ratio of the thickness of the high CTE resin film to the thickness of the low CTE resin film (the high CTE resin film: the low CTE resin film) is 1:10 to 10:1. [6] The laminate according to any one of [1] to [5], wherein the surface of the low CTE resin film and / or the high CTE resin film has been subjected to a surface treatment selected from corona treatment, plasma treatment, and ultraviolet treatment. [7] The laminate according to any one of [1] to [5], wherein the surface of the low CTE resin film and / or the high CTE resin film is subjected to a surface treatment with a coupling agent. [8] A metal-clad laminate obtained by laminating a metal film on one or both sides of the laminate according to any one of [1] to [7]. [9] A method for producing a laminate according to any one of [1] to [7], comprising arranging the high CTE resin film, the low CTE resin film, and the high CTE resin film in this order, and thermocompression bonding them to obtain the laminate.

[10] The method for producing a laminate according to [9], wherein the thermocompression bonding is carried out at a temperature in the range of -10°C to 20°C relative to the melting point of the high CTE resin film.

[11] A method for producing a metal-clad laminate according to [8], comprising arranging a metal film on both sides or one side of the laminate produced by [9] or

[10] , and thermocompression bonding the laminate to obtain the metal-clad laminate.

[12] A method for producing a metal-clad laminate according to [8], A metal film, the high CTE resin film, the low CTE resin film, and the high CTE resin film are arranged in this order and then thermally compressed together, or A method for producing a metal-clad laminate, comprising arranging a metal film, the high CTE resin film, the low CTE resin film, the high CTE resin film, and a metal film in this order, and then thermocompression bonding the resulting metal-clad laminate.

[13] The method for producing a metal-clad laminate according to

[11] or

[12] , wherein the thermocompression bonding is carried out at a temperature in the range of -10°C to 20°C relative to the melting point of the high CTE resin film. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a metal-clad laminate (e.g., a copper-clad laminate (CCL)) that has good electrical properties (dielectric properties) compatible with 5G, has excellent adhesion (tightness) between the substrate film (laminate) and the metal film, has excellent dimensional stability, and is suppressed from curling. Furthermore, according to the present invention, it is possible to provide a laminate for a printed wiring board, which is used to form the above-mentioned metal-clad laminate. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a laminate of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of the configuration of a metal-clad laminate of the present invention.

[0010] The laminate for printed wiring boards of the present invention and the metal-clad laminate of the present invention formed using the laminate will be described in detail below, but the description of the constituent elements described below is an example of one embodiment of the present invention and is not limited to these contents. The following definitions of terms apply throughout the specification and claims. The melting point in the present invention can be measured in accordance with JIS K 7121. Specifically, about 5 mg of a measurement sample is weighed out from a melt-extruded resin film, and the melting point is measured using a differential scanning calorimeter (SII Technologies, Inc.: high-sensitivity differential scanning calorimeter X-DSC 7000) at a heating rate of 10°C / min over a measurement temperature range of 20°C to 380°C. The film thickness of a resin film, metal film (metal foil film), etc. is determined by observing the cross section of the object to be measured using a microscope, measuring the thickness at five points, and averaging the measured values. In this specification, the low CTE resin film and the high CTE resin film may be collectively referred to as "resin film" in the description.

[0011] (Laminate) The laminate is a laminate for printed wiring boards and can be used to produce metal-clad laminates (copper-clad laminates (CCL)). The laminate is made up of three layers of resin films laminated together. The laminate is composed of a low-CTE resin film having a coefficient of linear thermal expansion (CTE) (CTE from 20°C to 140°C) of 50 ppm / °C or less, and a high-CTE resin film having a coefficient of linear thermal expansion (CTE) (CTE from 20°C to 140°C) of more than 50 ppm / °C laminated on both sides of the low-CTE resin film. A low CTE resin film does not have a melting point below 300° C. Also, a low CTE resin film does not melt at a temperature that is 30° C. higher than the melting point of a high CTE resin film. On the other hand, a high CTE resin film exhibits a melting point of 250° C. or higher. Furthermore, the tensile elongation at break of a high CTE resin film in the machine direction (MD direction) is 400% or less. In this specification, the coefficient of linear thermal expansion (CTE) is also referred to as the thermal expansion coefficient, the linear thermal expansion rate, or the thermal expansion rate.

[0012] <Layer structure of laminate> FIG. 1 is a cross-sectional view showing an example of the structure of the laminate of the present invention. The laminate 11 has a high CTE resin film 13, a low CTE resin film 12, and a high CTE resin film 14 laminated in this order.

[0013] <Low CTE resin film> The low-CTE resin film is disposed in the middle of a laminate formed by laminating three resin films, and has a linear thermal expansion coefficient (CTE) (CTE from 20°C to 140°C) of 50 ppm / °C or less. Furthermore, the low CTE resin film does not have a melting point below 300°C, and does not melt at a temperature that is 30°C higher than the melting point of the high CTE resin film. By disposing such a low CTE resin film in the center of the laminate, it is possible to effectively prevent deterioration of the dimensional stability of the laminate and curling of the laminate.

[0014] The coefficient of linear thermal expansion (CTE) (CTE at 20°C to 140°C) of the low-CTE resin film is preferably 5 to 50 ppm / °C, and more preferably 10 to 30 ppm / °C, because a value closer to the CTE of the metal film (e.g., copper film) to be laminated as a metal-clad laminate (e.g., copper-clad laminate (CCL)) provides better curl suppression and dimensional stability.

[0015] The coefficient of linear expansion (CTE) can be measured using a thermomechanical analyzer (TMA) in accordance with JIS K 7197: 1991. For example, it can be measured in tension mode using a thermomechanical analyzer (product name: SII / / SS7100, manufactured by Hitachi High-Tech Science Corporation) under conditions of a load of 50 mN and a heating rate of 5°C / min in the range of 10°C to 200°C, and the coefficient of linear expansion (ppm / °C) can be calculated from the slope in the range of 20°C to 140°C.

[0016] Since the low CTE resin film does not have a melting point below 300°C, it is preferably a film made of a thermosetting resin or a thermoplastic resin with a melting point higher than 300°C, and is preferably a film made of a resin selected from, for example, polyimide (PI), liquid crystal polymer (LCP), and oriented polyether ether ketone (oriented PEEK). When the low CTE resin film is made of a thermoplastic resin and has a melting point higher than 300° C., the low CTE resin film must also satisfy the requirement that it does not melt at a temperature obtained by adding 30° C. to the melting point of the high CTE resin film. In other words, the melting point of the low CTE resin film is higher than the temperature obtained by adding 30° C. to the melting point of the high CTE resin film. Furthermore, in the present invention, a highly flame-retardant resin is selected as the resin for forming the low CTE resin film, and the low CTE resin film is made to be a highly flame-retardant resin film, thereby making it possible to obtain a laminate with improved flame retardancy.

[0017] The low-CTE resin film may contain fillers and various additives to impart various functions to the resin film, such as strength, insulation properties, heat resistance, adjustment of the coefficient of linear thermal expansion (CTE), etc. Examples of additives include antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, plasticizers, and filler dispersants.

[0018] <<Filler>> Examples of fillers include inorganic fillers and organic fillers, which can be used alone or in combination.

[0019] Examples of inorganic fillers include mica, talc, boron nitride, magnesium oxide, silica, diatomaceous earth, titanium oxide, zinc oxide, etc. Among these, inorganic fillers such as mica, talc, boron nitride, magnesium oxide, and silica are preferred. The organic filler is not particularly limited, but examples thereof include organic particles such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyamide, polycarbonate, polyimide, polyether ketone, polyether ether ketone, polymethyl methacrylate, liquid crystal polymer, and polytetrafluoroethylene. The inorganic filler and the organic filler may be selected from the above and used alone or in combination of two or more. When two or more types are combined, the combination may be an inorganic filler and an organic filler.

[0020] <<Characteristics of low CTE resin film>> The film thickness of the low CTE resin film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 μm to 150 μm, more preferably 10 μm to 80 μm, and even more preferably 12 μm to 60 μm. If the film is too thick, the dielectric properties may deteriorate, and if the film is too thin, curling suppression and dimensional stability may become unstable.

[0021] The surface roughness (Rz) of the low-CTE resin film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 to 10 μm, for example. If the surface roughness is too small, the film will not be able to be wound up properly, while if it is too large, problems such as unstable adhesive strength and the inclusion of air bubbles will occur when the film is laminated with a high-CTE film. In this specification, surface roughness (Rz) refers to the ten-point average roughness of the film surface. The ten-point average roughness RzJIS can be determined based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009). In this specification, the surface roughness of each layer determined by the ten-point average roughness RzJIS is referred to as "surface roughness (Rz)."

[0022] [Measurement of ten-point average roughness RzJIS] The ten-point average roughness RzJIS (μm) of the sheet surface is obtained by measuring the roughness curve of the test piece using a laser microscope, measuring 10 samples from each roughness curve based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009), and calculating the average value.

[0023] The relative dielectric constant and dielectric dissipation factor of the low CTE resin film are not particularly limited and can be selected appropriately depending on the purpose, but for the purpose of reducing transmission loss of electrical signals, it is preferable that the relative dielectric constant is 3.5 or less and the dielectric dissipation factor is 0.025 or less. The low CTE resin film preferably has a low relative dielectric constant, but within a practically possible range, the dielectric constant is preferably 2.5 to 3.5, more preferably 3.0 to 3.5. The low CTE resin film also has a dielectric loss tangent of preferably 0.001 to 0.025, more preferably 0.001 to 0.01, and even more preferably 0.001 to 0.008.

[0024] [Dielectric constant and dielectric loss tangent] The relative dielectric constant and dielectric loss tangent of the resin film can be measured by the open resonator method using a network analyzer MS46122B (manufactured by Anritsu) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM) under conditions of a temperature of 23°C, humidity of 50%, and a frequency of 28 GHz.

[0025] Since the dielectric properties of the substrate deteriorate significantly when the substrate absorbs moisture, the water absorption rate of the low CTE resin film is, for example, preferably 0 to 2.5%, more preferably 0.01 to 2.0%, even more preferably 0.03 to 1.5%, and particularly preferably 0.05 to 1.2%.

[0026] [Water absorption rate] The water absorption rate can be determined in accordance with JIS K7209A method by measuring the sample by immersing it in water at 23°C for 24 hours. The water absorption rate is calculated from the change in mass before and after immersion in water. Water absorption rate = ((mass after 24-hour moisture test - mass before test) / mass before test) x 100

[0027] The surface of the low CTE resin film is preferably subjected to any surface treatment selected from corona treatment, plasma treatment, and ultraviolet treatment for reasons such as improving adhesion. The surface of the low CTE resin film may be subjected to a surface treatment with a coupling agent for the purpose of improving adhesion or the like. As the silane coupling agent, a known silane coupling agent can be used, such as an alkoxysilane.

[0028] <High CTE resin film> The high CTE resin films are disposed on both sides of the low CTE resin film, and the coefficient of linear thermal expansion (CTE) of the high CTE resin films (CTE at 20°C to 140°C) is greater than 50 ppm / °C. In addition, the melting point of the high CTE resin film is 250°C or higher. Furthermore, the high CTE resin film has a tensile elongation at break in the machine direction (MD) of 400% or less. By providing such a high CTE resin film, in combination with the low CTE resin film, it is possible to effectively prevent deterioration in the dimensional stability of the laminate and curling of the laminate.

[0029] The coefficient of linear thermal expansion (CTE) of the high CTE resin film (CTE at 20°C to 140°C) is, for example, preferably more than 50 ppm / °C and 250 ppm / °C or less, and more preferably 50 to 200 ppm / °C.

[0030] The high CTE resin film is preferably a thermoplastic resin film, and is preferably a film made of a resin selected from the group consisting of polyphenylene sulfide (PPS), polyphenylene ether (PPE), polyether ether ketone (PEEK), cycloolefin polymer (COP), thermoplastic polyimide (TPI), polystyrene (PS), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), and a polymer alloy made by mixing two or more types selected from these resins. Furthermore, in the present invention, a resin with high flame retardancy is selected as the resin for forming the high CTE resin film, and the high CTE resin film is made into a resin film with high flame retardancy, thereby making it possible to obtain a laminate with improved flame retardancy.

[0031] The tensile elongation at break in the machine direction (MD) (also referred to as the extrusion direction of the film) of a high CTE resin film is 400% or less as described above, but is preferably 20 to 350%. If the elongation is too large, problems such as the generation of wrinkles may occur when the film is bonded to a low CTE film or metal film.

[0032] [Elongation at break (%)] The elongation at tensile break of a high CTE film can be determined in accordance with JIS K7127 by measuring the elongation in the machine direction of the film (i.e., the extrusion direction of the film) at a tensile speed of 50 mm / min and a temperature of 23°C.

[0033] The high CTE resin film may contain fillers and various additives to impart various functions to the resin film, such as strength, insulation properties, heat resistance, and adjustment of the coefficient of linear thermal expansion (CTE). The fillers and various additives are as described above.

[0034] <<Characteristics of high CTE resin film>> The film thickness of each high CTE resin film arranged on both sides of the low CTE resin film is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 5 μm to 150 μm, more preferably 10 μm to 80 μm, and even more preferably 12 μm to 60 μm.

[0035] The ratio of the thickness of each high CTE resin film (one layer of high CTE resin film) arranged on both sides of the low CTE resin film to the thickness of the low CTE resin film (high CTE resin film:low CTE resin film) is preferably 1:10 to 10:1, more preferably 1:5 to 5:1, even more preferably 1:3 to 3:1, and desirably 2:5 to 3:2. If the low CTE resin film is too thick, the transmission properties may deteriorate, and if the low CTE resin film is too thin, curling may occur or dimensional stability may deteriorate.

[0036] The surface roughness (Rz) of the high CTE resin film at the interface between the low CTE resin film and the high CTE resin film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably, for example, 1 to 10 μm. On the other hand, the surface roughness (Rz) of the high CTE resin film at the interface between the high CTE resin film and the metal film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably, for example, 1 to 10 μm.

[0037] The high CTE resin film preferably has a relative dielectric constant of 3.5 or less and a dielectric loss tangent of 0.008 or less, more preferably 0.004 or less. The water absorption rate of the high CTE resin film is preferably 1% or less, and more preferably 0.3% or less. Metal-clad laminates (e.g., copper-clad laminates (CCL)) with high CTE resin films that satisfy these properties have good electrical properties (dielectric properties) that are compatible with 5G. The lower the relative dielectric constant of the high CTE resin film, the more desirable it is, but because the resin must have solder heat resistance, it is preferably 2.0 to 3.5, and more preferably 2.1 to 3.3. Also, the lower the dielectric loss tangent of the high CTE resin film, the more desirable it is, but because the resin must have solder heat resistance, it is preferably 0.0005 to 0.008, more preferably 0.0005 to 0.006, even more preferably 0.0005 to 0.004, and particularly preferably 0.0005 to 0.003.

[0038] Since the dielectric properties of the substrate deteriorate significantly when the substrate absorbs moisture, the water absorption rate of the high CTE resin film is, for example, preferably 0 to 1%, more preferably 0 to 0.8%, even more preferably 0 to 0.5%, and particularly preferably 0 to 0.2%.

[0039] [Water absorption rate] The water absorption rate can be determined in accordance with JIS K7209A method by measuring the sample by immersing it in water at 23°C for 24 hours. The water absorption rate is calculated from the change in mass before and after immersion in water. Water absorption rate = ((mass after 24-hour moisture test - mass before test) / mass before test) x 100

[0040] As shown in Figure 1, high CTE resin films are arranged on both sides of low CTE resin film 12, but high CTE resin film 13 and high CTE resin film 14 may be resin films of the same composition or different compositions as long as they satisfy the above-mentioned requirements.

[0041] For reasons such as improving adhesion, the surface of the high CTE resin film is preferably subjected to any surface treatment selected from corona treatment, plasma treatment, and ultraviolet treatment. The surface of the high CTE resin film may be subjected to a surface treatment with a coupling agent for the purpose of improving adhesion or the like.

[0042] <Method of manufacturing resin film> The resin film can be obtained, for example, by forming a resin into a film shape by melt extrusion molding. The melt extrusion molding method is a molding method in which a resin material is melt-kneaded using a melt extruder and then continuously extruded from a T-die of the melt extruder. For example, a resin material melted and kneaded in a melt extruder is continuously extruded into a strip-shaped resin film through a T-die at the tip of the melt extruder, and this continuous resin film is placed between rolls arranged next, cooled, and then wound up on a winder. In this way, a resin film is produced. The extruder is not particularly limited, and any extruder such as a single-screw extruder or a twin-screw extruder can be used.

[0043] (Metal-clad laminate) The metal-clad laminate of the present invention is obtained by laminating a metal film on one or both sides of the laminate of the present invention.

[0044] It is made by laminating a high CTE resin film, a low CTE resin film, a high CTE resin film, and a metal film in this order. The metal-clad laminate of the present invention may have metal films laminated on both sides of the substrate film, in which case the metal-clad laminate is formed by laminating a metal film, a high CTE resin film, a low CTE resin film, a high CTE resin film, and a metal film in this order.

[0045] Fig. 2 is a cross-sectional view showing an example of the configuration of the metal-clad laminate of the present invention, in which metal films are laminated on both sides of the laminate. Metal-clad laminate 21 has metal film 25, high CTE resin film 23, low CTE resin film 22, high CTE resin film 24, and metal film 26, which are laminated in this order.

[0046] The metal constituting the metal film is not particularly limited and can be appropriately selected depending on the purpose, but examples thereof include one selected from the group consisting of nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, and zinc, or alloys containing any one or more of these. Among these, copper and alloys containing copper are preferred from the viewpoints of shielding properties and economy. A preferred embodiment of the metal-clad laminate of the present invention is a metal-clad laminate in which a metal foil film is laminated to a laminate. Among these, a copper-clad laminate in which the metal foil is copper foil and a copper foil film (copper foil film) is laminated to a laminate is more preferred.

[0047] <Metal film> A preferred embodiment of the metal film is a metal foil film. The type of metal foil is not particularly limited, and for example, electrolytic metal foil, rolled metal foil, etc. can be used. Among the metal foils, copper foil is more preferable.

[0048] The thickness of the metal foil film is preferably 0.05 μm to 20 μm, more preferably 0.1 to 15 μm, from the viewpoint of ensuring sufficient electrical signal transmission characteristics and enabling a fine pitch of the circuit pattern. The surface roughness (Rz) of the metal foil film at the interface between the metal foil film and the high CTE resin film is preferably 0.5 μm or less, more preferably 0.3 μm or less, from the viewpoint of transmission characteristics due to the skin effect.

[0049] <Film thickness of metal-clad laminate> The thickness of the metal-clad laminate is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 to 300 μm, for example. If the thickness of the metal-clad laminate is equal to or greater than the lower limit of the above range, it can have excellent handleability and ensure strength. On the other hand, if the thickness is equal to or less than the upper limit of the above range, it can be made lighter, thinner, shorter, and more flexible.

[0050] (Method of manufacturing laminate) The method for manufacturing the laminate includes the steps of arranging a high CTE resin film, a low CTE resin film, and a high CTE resin film in this order, sandwiching them in a heat press or between heated rolls or heated belts, and applying heat and pressure to thermocompression bond the resin films together. The thermocompression bonding is preferably carried out at a temperature in the range of -10°C to 30°C, more preferably -10°C to 20°C, relative to the melting point of the high CTE resin film. The pressure in thermocompression bonding is preferably 0.2 to 10 MPa, more preferably 1 to 5 MPa, in the case of a heat press or a heating belt, and the thermocompression bonding time is preferably 1 to 30 minutes. In the case of a heating roll, the linear pressure is preferably 4 to 60 kN / m, and the linear speed is preferably 0.5 to 5.0 m / min.

[0051] (Metal-clad laminate manufacturing method) A method for producing a metal-clad laminate includes the steps of arranging a metal film on one or both sides of the laminate, and bonding the laminate and the metal film by thermocompression bonding. In addition, the method for manufacturing a metal-clad laminate includes a step of arranging a metal film, a high CTE resin film, a low CTE resin film, and a high CTE resin film in this order, sandwiching them in a heat press or between heated rolls or heated belts, and applying heat and pressure to thermocompression bond the metal film and each resin film, or arranging a metal film, a high CTE resin film, a low CTE resin film, a high CTE resin film, and a metal film in this order, thermocompression bond the metal film and each resin film. The thermocompression bonding is preferably carried out at a temperature in the range of -10°C to 30°C, more preferably -10°C to 20°C, relative to the melting point of the high CTE resin film.

[0052] When the metal-clad laminate is a metal-clad laminate having metal films on both sides of a laminate as shown in Figure 2, the metal-clad laminate may be manufactured by laminating a metal film on one side of the laminate using the method described above, and then laminating a metal film on the other side of the laminate using the same method, or the metal films on both sides may be laminated together on the laminate to manufacture a metal-clad laminate having metal films on both sides at the same time.

[0053] Before forming the metal film, the surface of the high CTE resin film on the side that comes into contact with the metal film may be surface-treated by corona treatment, plasma treatment, ultraviolet treatment, or the like.

[0054] The laminate of the present invention (particularly, the double-sided metal-clad laminate) has good electrical properties (dielectric properties), excellent adhesion (tightness) between the base film (laminate) and the metal film, and excellent dimensional stability and curl suppression, and therefore can be suitably used in the production of flexible printed circuit boards and rigid printed circuit boards. For example, a printed circuit board can be manufactured by processing the metal substrate of the metal-clad laminate of the present invention into a transmission circuit (conductor circuit) having a predetermined shape by etching or electrolytic plating (semi-additive process (SAP process), modified semi-additive process (MSAP process)). In manufacturing a printed circuit board, after forming a transmission circuit, an interlayer insulating film may be formed on the transmission circuit, and another transmission circuit may be formed on the interlayer insulating film. Also, a solder resist or a coverlay film may be laminated on the transmission circuit. [Example]

[0055] The present invention will be described in further detail below with reference to examples, but the scope of the present invention is not limited to these examples. In the following, parts and percentages are by weight unless otherwise specified.

[0056] (Water absorption rate (%)) The water absorption rate was measured in accordance with JIS K7209A by immersing the sample in water at 23°C for 24 hours. The water absorption rate was calculated from the change in mass before and after immersion in water.

[0057] (Dielectric properties) The dielectric properties (relative permittivity and dielectric loss tangent) were measured at a frequency of around 28 GHz at 23°C and 50% RH using an electronic measuring instrument (product name: Compact USB Vector Network Analyzer MS46122B, manufactured by Anritsu) using the Fabry-Perot method, a type of open-type resonator method. An open-type resonator (product name: Fabry-Perot Resonator Model No. DPS03, manufactured by Keycom) was used.

[0058] (Coefficient of linear thermal expansion (CTE) (ppm / ℃)) The coefficient of linear thermal expansion (CTE) was measured in tension mode using a thermomechanical analyzer (product name: SII / / SS7100, manufactured by Hitachi High-Tech Science Corporation) under conditions of a load of 50 mN and a heating rate of 5°C / min in the range of 10°C to 200°C, and the coefficient of linear thermal expansion (ppm / °C) was calculated from the slope in the range of 20°C to 140°C. Measurements were taken in the transverse direction (TD) of the resin film.

[0059] (Melting point (℃)) The melting point was measured in accordance with JIS K 7121. Specifically, approximately 5 mg of a measurement sample was weighed out from the melt-extruded resin film, and the sample was measured using a differential scanning calorimeter (SII Technologies, Inc.: high-sensitivity differential scanning calorimeter X-DSC 7000) at a heating rate of 10°C / min over a measurement temperature range of 20°C to 380°C.

[0060] (stretch(%)) The tensile elongation at break (elongation at tensile break) of the high CTE film was measured in the longitudinal direction of the film (i.e., the extrusion direction of the film) at a tension speed of 50 mm / min and a temperature of 23°C in accordance with JIS K7127.

[0061] The resin films and copper foil films used in the following Examples and Comparative Examples are as follows: The properties of the resin films are shown in Table 1 below.

[0062] (resin film) PPS film: PPS film manufactured by Shin-Etsu Polymer Co., Ltd. PPE-PPS film: PPE-PPS film manufactured by Shin-Etsu Polymer Co., Ltd. Non-oriented PEEK film: Non-oriented PEEK film manufactured by Shin-Etsu Polymer Co., Ltd. TPI film: TPI film manufactured by Shin-Etsu Polymer Co., Ltd. PI film: PI Kapton (registered trademark) H series manufactured by Toray DuPont PI film: PI Kapton (registered trademark) LK series manufactured by Toray DuPont LCP film: High-melting point LCP (1) film manufactured by Shin-Etsu Polymer Co., Ltd. Stretched PEEK film: Kurabo Stretched PEEK film LCP film: Low melting point LCP (2) film manufactured by Shin-Etsu Polymer Co., Ltd. PFA film: PFA film manufactured by Shin-Etsu Polymer Co., Ltd. (Copper foil film) Copper foil: CF-T9DA-SV-12 manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd. (Rz: 0.21μm, CTE: 18ppm / ℃)

[0063] [Table 1]

[0064] Example 1 A polyimide film (PI) (manufactured by Toray DuPont Co., Ltd., Kapton (registered trademark) LK series film) having a thickness of 50 μm and shown in Table 1 was prepared. The front and back surfaces of the polyimide film were subjected to a corona treatment. A 25 μm thick polyphenylene sulfide film (PPS) (Shin-Etsu SeplaFilm manufactured by Shin-Etsu Polymer Co., Ltd.) shown in Table 1 was placed on both sides of the polyimide film, and a heat-resistant release film (PI25x1-J0(LM)-ASI5: manufactured by Nippa Corporation) was placed on both outermost surfaces. The laminate was then laminated using a thermal laminator at a temperature of 295°C, a linear pressure of 20 kN / m, and a linear speed of 2 m / min. The used heat-resistant release film was then discarded to obtain the laminate of Example 1. Furthermore, a 12 μm thick copper foil film (CF-T9DA manufactured by Fukuda Metal Foil and Powder Co., Ltd.) was placed on both surfaces of the outermost surface, and the film was sandwiched between 1 mm thick stainless steel plates (SUS plates) using a heat press. The surface pressure was set to 3 MPa, and the hot plate temperature of the heat press was set to 295°C. The film was then heat-pressed for 5 minutes to obtain a copper-clad laminate (CCL). The configuration of the copper-clad laminate of Example 1 thus obtained is shown in the following Tables 2-1 and 2-2 (collectively referred to as Table 2). The copper-clad laminate of Example 1 was evaluated for curl, dimensions at 250°C, transmission characteristics, peel strength, and flame retardancy by the following evaluation methods. The results are shown in Table 4 below.

[0065] (Curl test) A test specimen measuring 150 x 150 mm was cut out from the obtained copper-clad laminate (CCL), and the copper foil on only one side of the test specimen was removed using an aqueous solution of iron chloride. The test specimen was then placed on a flat glass plate, and the amount of lift at each of the four corners of the test specimen was measured with a ruler, and the average value was calculated.

[0066] [Evaluation criteria for curl test] 〇 The average of the four points is 5cm or less × The average of the four points is greater than 5 cm

[0067] (250℃ dimensional test) The 250°C dimensional shrinkage test was performed in accordance with JIS C 6481:1996. First, a copper-clad laminate (CCL) was cut to a size of 300 x 300 mm, and four holes were punched at the edges of this laminate. The distance between the centers of the holes was measured. The laminated copper foil was then removed with an aqueous solution of iron chloride, and the sheet was placed in an oven at 250°C for 30 minutes. After removal, the dimensions were measured. A two-dimensional measuring machine (product name: VMH600, manufactured by Mino Group Co., Ltd.) was used to measure the dimensions.

[0068] [Evaluation criteria for 250℃ dimensional test] ◎ Shrinkage rate is 0.2% or less (good shrinkage rate) Shrinkage rate is greater than 0.2% and less than 0.3% △ Shrinkage rate is greater than 0.3% and less than 0.4% × Shrinkage rate is greater than 0.4% (poor shrinkage rate)

[0069] (Transmission characteristics test) For the transmission characteristic test, a microstrip line with a length of 10 cm and an impedance of 50 Ω was fabricated by etching the copper foil in a copper-clad laminate (CCL), and the transmission characteristics were measured at 30 GHz under the conditions of a temperature of 25°C and humidity of 50%. The measurement equipment used was a network analyzer E8363B (Keysight Technologies).

[0070] [Evaluation criteria for transmission characteristics test] ◎ Less than 5dB (30GHz) 〇 More than 5dB and less than 7dB △ More than 7dB and less than 10dB × Greater than 10dB

[0071] (peel strength test) For the peel strength test, a copper clad laminate (CCL) was cut into a 25 mm wide test piece, and the copper clad laminate (CCL) was fixed to a support and the copper foil was fixed to a pulling jig at a peel rate of 0.3 mm / min and a peel angle of 180°, in accordance with JIS Z 0237:2009, and the peel strength was measured when the copper foil was pulled from the copper clad laminate (CCL).

[0072] [Evaluation criteria for peel strength test] 〇 7N / cm or more △ 3N / cm or more and less than 7N / cm × 3N / cm or less

[0073] (Flame retardancy test) For the flame retardancy test, test specimens were prepared based on UL-94 (VTM test) and a combustion test was carried out based on the VTM method. The test pieces were cut out from copper clad laminates (CCL) after the copper foil had been completely removed with an aqueous solution of iron chloride.

[0074] [Evaluation criteria for flame retardancy testing] 〇 VTM-0 △ VTM-1 × Does not meet the conditions for VTM-0 and VTM-1

[0075] (Examples 2 to 14) Copper-clad laminates of Examples 2 to 14 were produced in the same manner as in Example 1, except that the type of resin film used and the thermocompression bonding temperature conditions were changed as shown in Table 2.

[0076] The copper-clad laminates produced in Examples 2 to 14 were evaluated in the same manner as in Example 1. Table 4 shows the evaluation results for the copper-clad laminates of Examples 2 to 14.

[0077] (Comparative Examples 1 to 7) Copper-clad laminates of Comparative Examples 1 to 7 were produced in the same manner as in Example 1, except that the type of resin film used and the thermocompression bonding temperature conditions in Example 1 were changed as shown in Tables 3-1 and 3-2 (collectively referred to as Table 3). Note that in Comparative Example 5, numerous wrinkles occurred, making it impossible to laminate the laminate.

[0078] The copper-clad laminates produced in Comparative Examples 1 to 7 were evaluated in the same manner as in Example 1. Table 4 shows the evaluation results for the copper-clad laminates of Comparative Examples 1 to 7.

[0079] [Table 2-1]

[0080] [Table 2-2]

[0081] [Table 3-1]

[0082] [Table 3-2]

[0083] [Table 4]

[0084] From the examples, it was confirmed that the metal-clad laminate of the present invention has good electrical properties (dielectric properties), excellent adhesion (tightness) between the base film (laminate) and the metal film, excellent dimensional stability, and suppressed curling. [Industrial Applicability]

[0085] The metal-clad laminate of the present invention can be suitably used in the production of FPC-related products for electronic devices such as smartphones, mobile phones, optical modules, digital cameras, game consoles, notebook computers, and medical instruments. [Explanation of symbols]

[0086] 11 Laminate 12 Low CTE resin film 13 High CTE resin film 14 High CTE resin film 21 Metal-clad laminate 22 Low CTE resin film 23 High CTE resin film 24 High CTE resin film 25 Metal Film 26 Metal Film

Claims

1. a low-CTE resin film having a coefficient of linear thermal expansion (CTE) of 50 ppm / °C or less; A laminate obtained by laminating a high CTE resin film having a coefficient of linear thermal expansion (CTE) of more than 50 ppm / °C on both sides of the low CTE resin film, The low CTE resin film has a melting point of not more than 300°C, The low CTE resin film does not melt at a temperature that is 30° C. above the melting point of the high CTE resin film; The high CTE resin film exhibits a melting point of 250°C or higher; The high CTE resin film has a tensile break elongation in the machine direction (MD direction) of 400% or less, A laminate in which the ratio of the thickness of the high CTE resin film (thickness of one layer of high CTE resin film) to the thickness of the low CTE resin film (the high CTE resin film:the low CTE resin film) is 1:1 to 1:

5.

2. The laminate of claim 1 , wherein the high CTE resin film has a relative dielectric constant of 3.5 or less and a dielectric loss tangent of 0.008 or less.

3. The laminate of claim 1 , wherein the high CTE resin film has a water absorption rate of 1% or less.

4. The laminate of claim 1 , wherein the low CTE resin film has a water absorption rate of 2.5% or less.

5. The laminate according to claim 1 , wherein the surface of the low CTE resin film and / or the high CTE resin film has been subjected to any surface treatment selected from the group consisting of corona treatment, plasma treatment, and ultraviolet treatment.

6. The laminate according to claim 1 , wherein a surface of the low CTE resin film and / or the high CTE resin film is subjected to a surface treatment with a coupling agent.

7. A metal-clad laminate obtained by laminating a metal film on one or both sides of the laminate according to any one of claims 1 to 6.

8. A method for manufacturing a laminate according to any one of claims 1 to 6, comprising arranging the high CTE resin film, the low CTE resin film, and the high CTE resin film in this order, and thermocompression bonding the resulting laminate.

9. A method for manufacturing the metal-clad laminate according to claim 7, comprising: a metal film, the high CTE resin film, the low CTE resin film, and the high CTE resin film are arranged in this order and then thermally compressed; A method for producing a metal-clad laminate, comprising arranging a metal film, the high CTE resin film, the low CTE resin film, the high CTE resin film, and a metal film in this order, and then thermocompression bonding the resulting laminate to obtain the metal-clad laminate.

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