Manufacturing method of metal-clad laminate

Abstract

To provide a metal-clad laminate which can enhance adhesion between a heat fusible resin layer having adhesion to a metal layer, and a thermosetting polyimide layer, and a method for manufacturing the same.SOLUTION: A metal-clad laminate 11 includes an insulating layer 12, and a metal layer 13 laminated on one surface or both surfaces of the insulating layer 12. The insulating layer 12 includes a thermosetting polyimide layer 21, and a heat fusible resin layer 31 provided between the thermosetting polyimide layer 21 and the metal layer 13. The thermosetting polyimide layer 21 is composed of a thermosetting polyimide film having a water contact angle of a main surface bonded to the heat fusible resin layer 31 of 20° or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a metal clad laminate. Board It relates to a manufacturing method. [Background technology]

[0002] In recent years, with the use of IoT (Internet of Things), electronic devices such as sensors tend to be used in various environments. For example, millimeter waves used in sensors and the like are highly stable against light, weather, and the environment, and are therefore used in millimeter wave radars in automobiles and are expected to be used in harsher environments. In this way, electronic devices in recent years may be used in harsher environments, and as a result, there is a demand for improving the environmental resistance of electronic devices. Here, a metal-clad laminate having a laminated structure of a polyimide layer as an insulating layer and a copper layer as a metal layer is used for the printed wiring board equipped in the electronic device. For example, Patent Document 1 discloses a polyimide film suitable for the polyimide layer of a metal-clad laminate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-106137 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned metal-clad laminate, by providing a heat-sealed resin layer between the thermosetting polyimide layer and the metal layer, it is possible to improve the adhesion between the insulating layer having the thermosetting polyimide layer and the heat-sealed resin layer and the metal layer. Thus, there is room for improvement in the adhesion between the heat-sealed resin layer having adhesion to the metal layer and the thermosetting polyimide layer. [Means for solving the problem]

[0005] The metal-clad laminate that solves the above problems is a metal-clad laminate comprising an insulating layer and a metal layer laminated on one or both sides of the insulating layer, wherein the insulating layer comprises a thermosetting polyimide layer and a heat-sealed resin layer provided between the thermosetting polyimide layer and the metal layer, and the thermosetting polyimide layer is composed of a thermosetting polyimide film having a water contact angle of 20° or less on the main surface bonded to the heat-sealed resin layer.

[0006] According to this configuration, the main surface of the thermosetting polyimide film that is bonded to the heat-sealed resin layer is in a state that is prone to hydrogen bonding, for example, so that the bonding strength between the thermosetting polyimide layer and the heat-sealed resin layer can be increased.

[0007] In the metal-clad laminate, the thermosetting polyimide layer preferably contains 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as copolymerization components, which allows the metal-clad laminate to exhibit excellent low dielectric properties.

[0008] In the above metal-clad laminate, the heat-sealing resin layer preferably has a melting point of not less than 280° C. According to this configuration, the solder heat resistance of the metal-clad laminate can be easily improved. In the above metal-clad laminate, the metal layer is preferably made of a metal foil having a ten-point average roughness (Rzjis) of 2.0 or less on the main surface to be bonded to the thermally fused resin layer. With this configuration, the smoothness of the main surface of the metal foil is increased, thereby suppressing the skin effect in which high-frequency current is concentrated on the surface of the metal layer, and the metal layer can fully exhibit the electrical characteristics of the high-frequency band.

[0009] In the above metal-clad laminate, the linear expansion coefficient of the thermosetting polyimide layer is preferably within a range of 10 ppm / K to 26 ppm / K inclusive. This configuration can improve, for example, the dimensional stability of the metal-clad laminate.

[0010] In the above metal-clad laminate, the water absorption rate of the heat-sealed resin layer is preferably lower than that of the thermosetting polyimide layer. With this configuration, it is presumed that the change in the state of the interface between the metal layer and the heat-sealed resin layer can be suppressed by suppressing water absorption and dehydration of the heat-sealed resin layer bonded to the metal layer. As a result, the decrease in adhesion of the metal layer to the insulating layer having the thermosetting polyimide layer can be suppressed during long-term use accompanied by temperature changes.

[0011] In the above metal-clad laminate, the interlayer peel strength between the thermosetting polyimide layer and the heat-sealable resin layer is preferably 0.6 N / mm or more. In the metal-clad laminate, the heat-sealing resin layer is preferably made of a fluororesin, which can keep the dielectric constant of the insulating layer low, thereby allowing the electrical characteristics in the high frequency band, for example, to be fully exhibited.

[0012] In the above metal-clad laminate, the thermosetting polyimide layer is composed of a thermosetting polyimide film whose main surface located on the heat-sealable resin layer side has been discharge-treated, and in a surface analysis of the thermosetting polyimide film using X-ray photoelectron spectroscopy, it is preferable that a ratio R calculated from an integrated value A1 of 527 to 536 eV before the discharge treatment and an integrated value A2 of 527 to 536 eV after the discharge treatment by the following formula (1) is 1.35 or more.

[0013] R = A2 / A1 (1) In the metal-clad laminate, the thermosetting polyimide layer is composed of a thermosetting polyimide film whose main surface located on the heat-sealing resin layer side has been subjected to a discharge treatment, and in a surface analysis of the thermosetting polyimide film using X-ray photoelectron spectroscopy, when the sum of the integrated values ​​of 278 to 298 eV, 391 to 411 eV, 523 to 543 eV, and 94 to 114 eV is taken as 100% and the percentage of the integrated value of 523 to 543 eV in the total 100% is taken as the oxygen atom content, it is preferable that the change in oxygen atoms C (%) calculated from the oxygen atom content B1 (%) before the discharge treatment and the oxygen atom content B2 (%) after the discharge treatment using the following formula (2) is 5% or more.

[0014] C(%) = B2 - B1 (2) A method for manufacturing a metal-clad laminate includes an insulating layer and a metal layer laminated on one or both sides of the insulating layer, the insulating layer including a thermosetting polyimide layer and a heat-sealed resin layer provided between the thermosetting polyimide layer and the metal layer, the thermosetting polyimide layer being composed of a thermosetting polyimide film having a water contact angle of 20° or less on a main surface bonded to the heat-sealed resin layer, and the method preferably includes a step of thermocompressing a laminate in which a thermoplastic resin film that becomes the heat-sealed resin layer is disposed between the thermosetting polyimide film and a metal foil that becomes the metal layer. Effect of the Invention

[0015] According to the present invention, it is possible to improve the adhesion between the heat-sealing resin layer, which has adhesiveness to a metal layer, and the thermosetting polyimide layer. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a metal-clad laminate according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating a method for manufacturing a metal-clad laminate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of a metal-clad laminate and a method for manufacturing the same will be described. Note that in the drawings, the thickness of each layer constituting the metal-clad laminate may be exaggerated. 1, the metal-clad laminate 11 includes an insulating layer 12 and a metal layer 13 laminated on the insulating layer 12. The metal layer 13 in this embodiment is composed of a first metal layer 13a laminated on one main surface of the insulating layer 12 and a second metal layer 13b laminated on the other main surface of the insulating layer 12.

[0018] The insulating layer 12 includes a thermosetting polyimide layer 21 and a heat-sealed resin layer 31. The heat-sealed resin layer 31 includes a first heat-sealed resin layer 31a provided between the thermosetting polyimide layer 21 and the first metal layer 13a, and a second heat-sealed resin layer 31b provided between the thermosetting polyimide layer 21 and the second metal layer 13b. Thus, the metal-clad laminate 11 of this embodiment is a double-sided metal-clad laminate having a five-layer structure including an insulating layer 12 having a three-layer structure including the thermosetting polyimide layer 21, the first heat-sealed resin layer 31a, and the second heat-sealed resin layer 31b, and having metal layers 13 laminated on both sides of the insulating layer 12.

[0019] <Thermosetting polyimide layer 21> The thermosetting polyimide layer 21 is composed of a thermosetting polyimide film having a water contact angle of 20° or less on the main surface to be bonded to the heat-sealing resin layer 31. The water contact angle of the thermosetting polyimide film is preferably 17° or less, more preferably 14° or less. The water contact angle of the thermosetting polyimide film is preferably 5° or more, more preferably 6° or more, from the viewpoint of productivity, for example. A thermosetting polyimide film having a main surface with a water contact angle of 20° or less can be obtained, for example, by subjecting the main surface of the thermosetting polyimide film to a discharge treatment. That is, a hydrophilic group can be introduced into the main surface of the thermosetting polyimide film by a discharge treatment. The hydrophilic group introduced in this way can reduce the water contact angle of the main surface of the thermosetting polyimide film.

[0020] The thermosetting polyimide film is obtained from an acid component and a diamine component. Examples of the acid component include 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and pyromellitic acid. Examples of the diamine component include p-phenylenediamine (PPD), 4,4-diaminodiphenyl ether, m-tolidine, and 4,4'-diaminobenzanilide. Examples of commercially available thermosetting polyimide films include UPILEX-S (trade name) and UPILEX-SGA (trade name) manufactured by Ube Industries, Ltd.

[0021] From the viewpoint of excellent low dielectric properties such as low dielectric constant and low dielectric loss tangent, the thermosetting polyimide layer 21 preferably contains 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as copolymerization components. The content of 3,3',4,4'-biphenyltetracarboxylic dianhydride in the thermosetting polyimide layer 21 is preferably 50 mol% or more, more preferably 70 mol% or more, when the total acid components are taken as 100 mol%. The content of p-phenylenediamine in the thermosetting polyimide layer 21 is preferably 50 mol% or more, more preferably 70 mol% or more, when the total diamine components are taken as 100 mol%. An example of a commercially available thermosetting polyimide film containing 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as copolymerization components is Upilex-SGA (trade name) manufactured by Ube Industries, Ltd.

[0022] Examples of discharge treatments for thermosetting polyimide films include corona discharge treatment, atmospheric pressure plasma discharge treatment, and vacuum plasma discharge treatment. Among the discharge treatments, corona discharge treatment is preferred from the viewpoint of reducing equipment costs and improving productivity. The conditions for the discharge treatment may be adjusted so as to achieve the above water contact angle. For example, in corona discharge treatment, the discharge amount is 20 W·min / m 2 More than 500W min / m 2 This can be done by setting the following ranges.

[0023] In a thermosetting polyimide film having a main surface with a water contact angle of 20° or less, oxygen atoms due to hydrophilic groups are detected in a surface analysis using X-ray photoelectron spectroscopy (XPS). In the surface analysis of the thermosetting polyimide film using XPS, the ratio R calculated from the integrated value A1 from 527 to 536 eV before the discharge treatment and the integrated value A2 from 527 to 536 eV after the discharge treatment by the following formula (1) is preferably 1.35 or more.

[0024] R = A2 / A1 (1) In the surface analysis of the thermosetting polyimide film using XPS, the content of oxygen atoms can be expressed based on the total of carbon atoms, nitrogen atoms, oxygen atoms, and silicon atoms. That is, the sum of the integrated values ​​of 278 to 298 eV (carbon atoms), 391 to 411 eV (nitrogen atoms), 523 to 543 eV (oxygen atoms), and 94 to 114 eV (silicon atoms) is taken as 100%. The percentage of the integrated value of 523 to 543 eV (oxygen atoms) in this total of 100% can be expressed as the content of oxygen atoms. The change amount C (%) of oxygen atoms calculated from the content B1 (%) of oxygen atoms before discharge treatment and the content B2 (%) of oxygen atoms after discharge treatment by the following formula (2) is preferably 5% or more.

[0025] C(%) = B2 - B1 (2) The thickness of the thermosetting polyimide layer 21 is preferably, for example, 125 μm or less. The water absorption rate of the thermosetting polyimide layer 21 is preferably, for example, within a range of 1.0% or more and 2.0% or less.

[0026] <Heat-sealing resin layer 31> The water absorption rate of the thermal adhesive resin layer 31 is preferably lower than that of the thermosetting polyimide layer 21, more preferably 0.1% or less, further preferably 0.07% or less, and most preferably 0.05% or less.

[0027] The thermal adhesive resin layer 31 preferably has a melting point of 280° C. or more from the viewpoint of easily increasing the solder heat resistance, for example. The melting point of the thermal adhesive resin layer 31 is preferably 320° C. or less from the viewpoint of ease of thermal fusion.

[0028] The thickness of the first heat-sealed resin layer 31a and the thickness of the second heat-sealed resin layer 31b are preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 12.5 μm or more. The thickness of the first heat-sealed resin layer 31a and the thickness of the second heat-sealed resin layer 31b are preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less. The thickness of the first heat-sealed resin layer 31a and the thickness of the second heat-sealed resin layer 31b may be the same as or different from each other. From the viewpoint of suppressing twisting and warping of the metal-clad laminate 11, the difference in thickness between the first heat-sealed resin layer 31a and the second heat-sealed resin layer 31b is preferably 3 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

[0029] The thickness of the insulating layer 12 of this embodiment is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more. From the viewpoint of further increasing flexibility, the thickness of the insulating layer 12 of this embodiment is preferably 400 μm or less, and more preferably 300 μm or less.

[0030] From the viewpoint of keeping the dielectric constant low, the thermal adhesive resin layer 31 is preferably made of a fluororesin. Among the fluororesins, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) or tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) is preferred from the viewpoint of having good low dielectric properties and good adhesiveness.

[0031] <Metal layer 13> Examples of the metal of the metal layer 13 include gold, silver, copper, copper alloy, aluminum, and aluminum alloy. The first metal layer 13a and the second metal layer 13b may be made of the same metal or different metals. The metal layer 13 can be formed using, for example, a copper foil. Examples of the copper foil include electrolytic copper foil and rolled copper foil. The metal foil forming the first metal layer 13a and the metal foil forming the second metal layer 13b may be obtained by the same manufacturing method or by different manufacturing methods.

[0032] The thickness of the first metal layer 13a and the thickness of the second metal layer 13b are preferably in the range of 2 μm or more and 105 μm or less, and more preferably in the range of 2 μm or more and 35 μm or less. The thickness of the first metal layer 13a and the thickness of the second metal layer 13b may be the same as each other or may be different from each other.

[0033] Here, the adhesive strength between the metal layer 13 and the heat-sealing resin layer 31 tends to increase as the surface roughness of the main surface of the metal foil that is adhered to the heat-sealing resin layer 31 increases. On the other hand, the main surface of the metal foil is smoother, which suppresses the skin effect in which the current in the high frequency band is concentrated on the surface of the metal layer 13, and thus allows the electrical characteristics of the high frequency band to be fully exhibited. In recent years, with the increase in the frequency of electronic devices such as 5G smartphones, the demand for printed wiring boards with smaller transmission loss has been increasing. For this reason, when the metal-clad laminate 11 is used as a printed wiring board compatible with the high frequency band, the metal layer 13 is preferably composed of a metal foil having a ten-point average roughness (Rzjis) of 2.0 or less on the main surface that is adhered to the heat-sealing resin layer 31. The ten-point average roughness (Rzjis) is specified in JIS B0601 (2001). The ten-point average roughness (Rzjis) of the main surface of the metal foil is more preferably 1.5 or less, and even more preferably 1.0 or less.

[0034] <Linear expansion coefficient and peel strength> By bringing the linear expansion coefficient of the insulating layer 12 closer to the linear expansion coefficient of the metal layer 13, the dimensional stability of the metal-clad laminate 11 can be improved. For example, the linear expansion coefficient of copper is 18 ppm / K. When the metal layer 13 is a copper layer, the linear expansion coefficient of the insulating layer 12 is preferably within a range of, for example, 10 ppm / K or more and 40 ppm / K or less. The linear expansion coefficient of the thermosetting polyimide layer 21 constituting the insulating layer 12 is preferably within a range of 10 ppm / K or more and 26 ppm / K or less. For example, even if the linear expansion coefficient of the heat-sealing resin layer 31 is larger than the linear expansion coefficient of the thermosetting polyimide layer 21, the dimensional stability of the metal-clad laminate 11 can be improved by setting the linear expansion coefficient of the thermosetting polyimide layer 21 to the above range.

[0035] The peel strength between the thermosetting polyimide layer 21 and the thermal adhesive resin layer 31 is preferably 0.6 N / mm or more. <Method of manufacturing metal-clad laminate 11> Next, a method for manufacturing the metal-clad laminate 11 will be described.

[0036] As shown in Fig. 2, the manufacturing method of the metal-clad laminate 11 includes a step of thermocompression bonding a laminate 111 in which a thermoplastic resin film 131 is disposed between a thermosetting polyimide film 121 and a metal foil 113. The thermosetting polyimide film 121 forms the above-mentioned thermosetting polyimide layer 21. The first thermoplastic resin film 131a and the second thermoplastic resin film 131b form the first heat-sealed resin layer 31a and the second heat-sealed resin layer 31b, respectively. The first metal foil 113a and the second metal foil 113b form the first metal layer 13a and the second metal layer 13b, respectively.

[0037] In the step of thermocompression bonding the laminate 111, the laminate 111 is heated to a temperature equal to or higher than the melting point of the thermoplastic resin film 131. When the melting point of the thermoplastic resin film 131 is Tm°C, the maximum temperature in the step of thermocompression bonding the laminate 111 is preferably Tm+70°C or lower.

[0038] The pressure in the step of thermocompression bonding the laminate 111 is, for example, 0.5 N / mm2 More than 10N / mm 2 It is preferable that the range is within the following range, and more preferably 2N / mm 2 More than 6N / mm 2 It is within the following range.

[0039] The heating time in the step of thermocompression bonding the laminate 111 is, for example, preferably in the range of 10 seconds or more and 600 seconds or less, and more preferably in the range of 30 seconds or more and 500 seconds or less. The step of thermocompression bonding the laminate 111 is preferably performed using a double belt press device 51. The double belt press device 51 heats and presses the laminate 111 while transporting it. The double belt press device 51 has a first transport section 52 located upstream in the transport direction of the laminate 111 and a second transport section 53 located downstream.

[0040] The first conveying section 52 is equipped with an upper first drum 52a and a lower first drum 52b. The second conveying section 53 is equipped with an upper second drum 53a and a lower second drum 53b. An endless upper belt 54 is stretched between the upper first drum 52a and the upper second drum 53a. An endless lower belt 55 is stretched between the lower first drum 52b and the lower second drum 53b. The first drums 52a and 52b are driven by the drive of the second drums 53a and 53b via the belts 54 and 55. The belts 54 and 55 are made of a metal such as stainless steel.

[0041] Between the first conveyor section 52 and the second conveyor section 53, an upper temperature adjustment device 56 and a lower temperature adjustment device 57 are disposed to face each other with the belts 54, 55 interposed therebetween. The upper temperature adjustment device 56 and the lower temperature adjustment device 57 heat and pressurize the laminate 111 via the upper belt 54 and the lower belt 55. The upper temperature adjustment device 56 and the lower temperature adjustment device 57 heat and pressurize the upper belt 54 and the lower belt 55 by a heat medium such as oil, for example.

[0042] By using the double belt press device 51, it is possible to continuously obtain the metal-clad laminate 11. By winding up the long metal-clad laminate 11, it is stored or transported as a roll product of the metal-clad laminate 11. The metal-clad laminate 11 can be used, for example, for a printed wiring board such as a flexible printed wiring board.

[0043] Next, the operation and effects of this embodiment will be described. (1) The insulating layer 12 of the metal-clad laminate 11 includes a thermosetting polyimide layer 21 and a heat-sealed resin layer 31 provided between the thermosetting polyimide layer 21 and the metal layer 13. The thermosetting polyimide layer 21 is composed of a thermosetting polyimide film 121 having a water contact angle of 20° or less on the main surface bonded to the heat-sealed resin layer 31.

[0044] According to this configuration, the main surface of the thermosetting polyimide film 121 that is bonded to the heat-sealed resin layer 31 is in a state that is prone to hydrogen bonding, for example, and therefore it is possible to increase the interlayer bonding strength between the thermosetting polyimide layer 21 and the heat-sealed resin layer 31. This makes it possible to increase the adhesion between the heat-sealed resin layer 31, which has adhesiveness to the metal layer 13, and the thermosetting polyimide layer 21.

[0045] (2) The thermosetting polyimide layer 21 preferably contains 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as copolymerization components, which makes it possible to exhibit excellent low dielectric properties.

[0046] (3) The thermal adhesive resin layer 31 preferably has a melting point of 280° C. or higher. In this case, the solder heat resistance of the metal-clad laminate 11 can be easily improved. (4) The metal layer 13 is preferably made of a metal foil having a ten-point average roughness (Rzjis) of 2.0 or less on the main surface to be bonded to the thermally fused resin layer 31. In this case, by increasing the smoothness of the main surface of the metal foil, it is possible to suppress the skin effect, in which high-frequency band currents are concentrated on the surface of the metal layer 13, and therefore the metal layer 13 can fully exhibit the electrical characteristics of the high-frequency band.

[0047] (5) The linear expansion coefficient of the thermosetting polyimide layer 21 is preferably within a range of 10 ppm / K or more and 26 ppm / K or less. In this case, the dimensional stability of the metal-clad laminate 11 can be improved.

[0048] (6) The water absorption rate of the thermally adhesive resin layer 31 is preferably lower than that of the thermosetting polyimide layer 21. In this case, it is presumed that by suppressing water absorption and dehydration of the thermally adhesive resin layer 31 bonded to the metal layer 13, it is possible to suppress changes in the state of the interface between the metal layer 13 and the thermally adhesive resin layer 31. This makes it possible to suppress a decrease in the adhesion of the metal layer 13 to the insulating layer 12 having the thermosetting polyimide layer 21 during long-term use accompanied by temperature changes.

[0049] (7) The peel strength between the thermosetting polyimide layer 21 and the heat-sealable resin layer 31 is preferably 0.6 N / mm or more. In this way, the adhesion between the thermosetting polyimide layer 21 and the heat-sealable resin layer 31 can be ensured.

[0050] (8) The thermal adhesive resin layer 31 is preferably made of a fluororesin. In this case, the dielectric constant of the insulating layer 12 can be kept low, so that, for example, the electrical characteristics in the high frequency band can be fully exhibited.

[0051] (9) In a surface analysis of the thermosetting polyimide film 121 using X-ray photoelectron spectroscopy, the ratio R calculated from the integrated value A1 from 527 to 536 eV before the discharge treatment and the integrated value A2 from 527 to 536 eV after the discharge treatment is preferably 1.35 or more. The thermosetting polyimide film 121 modified by the discharge treatment in this manner can be suitably used for the thermosetting polyimide layer 21.

[0052] (10) In a surface analysis of a thermosetting polyimide film using X-ray photoelectron spectroscopy, the change in oxygen atoms C (%) calculated from the oxygen atom content B1 (%) before discharge treatment and the oxygen atom content B2 (%) after discharge treatment is preferably 5% or more. The thermosetting polyimide film 121 modified by discharge treatment in this manner can be suitably used for the thermosetting polyimide layer 21.

[0053] (11) The method for manufacturing the metal-clad laminate 11 includes a step of thermocompression bonding a laminate 111 in which a thermoplastic resin film 131 serving as the thermally adhesive resin layer 31 is disposed between a thermosetting polyimide film 121 serving as the thermosetting polyimide layer 21 and a metal foil 113 serving as the metal layer 13. In this case, the metal-clad laminate 11 can be manufactured efficiently. In addition, in the step of thermocompression bonding the laminate 111, a double belt press device 51 is used, so that the metal-clad laminate 11 can be manufactured continuously, and therefore the manufacturing efficiency of the metal-clad laminate 11 can be easily improved.

[0054] (Example of change) The above embodiment may be modified as follows: The above embodiment and the following modified examples may be combined with each other to the extent that no technical contradiction occurs.

[0055] The metal-clad laminate 11 can also be manufactured using a laminating device other than the double belt press device 51. In the above embodiment, the long metal-clad laminate 11 is manufactured continuously, but metal-clad laminates of a predetermined size may be manufactured one by one.

[0056] In the above embodiment, the metal-clad laminate 11 is manufactured by one-stage thermocompression bonding, but it may also be manufactured by multiple stages of thermocompression bonding. For example, the metal-clad laminate 11 may be manufactured by a step of obtaining a laminated film by thermocompression bonding the thermosetting polyimide film 121 and the thermoplastic resin film 131, and a step of thermocompression bonding the laminated film and the metal foil 113.

[0057] In the above-mentioned metal-clad laminate 11, either one of the laminate structure consisting of the first heat-sealed resin layer 31a and the first metal layer 13a and the laminate structure consisting of the second heat-sealed resin layer 31b and the second metal layer 13b may be omitted. That is, the metal-clad laminate may be a single-sided metal-clad laminate having an insulating layer with a two-layer structure of a thermosetting polyimide layer and a heat-sealed resin layer, and a metal layer laminated on one side of the insulating layer. In the case of a single-sided metal-clad laminate, the thickness of the insulating layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 12.5 μm or more. In the case of a single-sided metal-clad laminate, the thickness of the insulating layer is preferably 200 μm or less, more preferably 150 μm or less, from the viewpoint of further increasing flexibility, for example. EXAMPLES

[0058] Next, examples and comparative examples will be described. Example 1 In Example 1, a metal-clad laminate was manufactured by laminating metal layers on both sides of an insulating layer. The thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film with a water contact angle of 12° on both main surfaces. This thermosetting polyimide film was obtained by subjecting a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-SGA) to discharge treatment. The discharge treatment was performed with a discharge amount of 155 W·min / m 2 A corona discharge treatment was used with a setting of 0.

[0059] The first and second heat-sealable resin layers of the insulating layer were both formed using a fluororesin film (manufactured by AGC Corporation, product name: EA-2000). The metal layer was formed using copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd., product name: TQ-M4-VSP). A double belt press machine was used for the process of thermocompression bonding the film and the copper foil.

[0060] The physical properties of each layer and the conditions for thermocompression bonding are shown in Table 1. The "water contact angle" shown in Table 1 is the average value of measurements taken three times by the sessile drop method using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name: DMs-401) on the thermosetting polyimide film after discharge treatment.

[0061] In addition, the surface of the thermosetting polyimide film was analyzed before and after discharge treatment using X-ray photoelectron spectroscopy (XPS). For this surface analysis, an X-ray photoelectron spectroscopy analyzer (ULVAC-PHI, Inc., product name: PHI 5000 Versa ProbeII) was used. In addition, AlKα rays (1486.6 eV) were used as the X-ray source for the surface analysis.

[0062] In the surface analysis of the thermosetting polyimide film using XPS, the ratio R was calculated according to the above formula (1) from the integrated value A1 from 527 to 536 eV before the discharge treatment and the integrated value A2 from 527 to 536 eV after the discharge treatment. In the "Increase in oxygen atoms" column in Table 1, the ratio R of 1.35 or more is indicated by "○", and the ratio R of less than 1.35 is indicated by "×".

[0063] In the surface analysis of the thermosetting polyimide film using XPS, the change in oxygen atom content C (%) was calculated from the oxygen atom content B1 (%) before the discharge treatment and the oxygen atom content B2 (%) after the discharge treatment according to (2) below. The results are shown in the "Change in oxygen atom content" column in Table 1.

[0064] The water absorption rates of the thermosetting polyimide layer and the heat-sealable resin layer shown in Table 1 were determined in accordance with JIS K7209:2000 (ASTM D570) from the measured weight change rate after immersing the films forming each layer in water at 23°C for 24 hours.

[0065] Example 2 In Example 2, except that the thicknesses of the first heat-sealable resin layer and the second heat-sealable resin layer were changed, a metal-clad laminate was produced in the same manner as in Example 1. The same double belt press device as in Example 1 was used for the step of thermocompression bonding the film and the copper foil. The physical properties of each layer and the conditions of thermocompression bonding are shown in Table 1.

[0066] Example 3 In Example 3, the thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film with a water contact angle of 8° on both main surfaces, and a metal-clad laminate was manufactured in the same manner as in Example 1, except that the thicknesses of the first heat-sealed resin layer and the second heat-sealed resin layer were changed. This thermosetting polyimide film was obtained by subjecting a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-SGA) to discharge treatment. For this discharge treatment, a discharge amount of 200 W·min / m was used. 2 The corona discharge treatment was performed with the setting set at 100° C. The film and the copper foil were thermocompression-bonded using the same double belt press as in Example 1. The physical properties of each layer and the thermocompression-bonding conditions are shown in Table 1.

[0067] Example 4 In Example 4, a metal-clad laminate was produced in the same manner as in Example 1, except that the thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film with a water contact angle of 15° on both main surfaces. This thermosetting polyimide film was obtained by subjecting a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-SGA) to discharge treatment. The discharge treatment was performed with a discharge amount of 310 W min / m 2 The corona discharge treatment was performed with the setting set at 100° C. The film and the copper foil were thermocompression-bonded using the same double belt press as in Example 1. The physical properties of each layer and the thermocompression-bonding conditions are shown in Table 1.

[0068] Example 5 In Example 5, the thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film having a water contact angle of 18° on both main surfaces and a thickness of 25 μm, and a metal-clad laminate was produced in the same manner as in Example 1, except that the thicknesses of the first heat-sealed resin layer and the second heat-sealed resin layer were changed. This thermosetting polyimide film was obtained by subjecting a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-SGA) to discharge treatment. For this discharge treatment, a discharge amount of 155 W·min / m was used. 2 The corona discharge treatment was performed with the setting set at 100° C. The film and the copper foil were thermocompression-bonded using the same double belt press as in Example 1. The physical properties of each layer and the thermocompression-bonding conditions are shown in Table 1.

[0069] Example 6 In Example 6, a metal-clad laminate was produced in the same manner as in Example 1, except that the metal layer was formed using a copper foil having a different ten-point average roughness (Rzjis) from the copper foil in Example 1. The same double belt press machine as in Example 1 was used for the step of thermocompression bonding the film and the copper foil. The physical properties of each layer and the thermocompression bonding conditions are shown in Table 2.

[0070] Comparative Example 1 In Comparative Example 1, a metal-clad laminate was produced in the same manner as in Example 1, except that the thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film with a water contact angle of 24° on both main surfaces. This thermosetting polyimide film was obtained by subjecting a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-S) to discharge treatment. The discharge treatment was performed with a discharge amount of 155 W·min / m 2 The corona discharge treatment was performed with the setting set at 100° C. The film and the copper foil were thermocompression-bonded using the same double belt press as in Example 1. The physical properties of each layer and the thermocompression-bonding conditions are shown in Table 2.

[0071] Comparative Example 2 In Comparative Example 2, the thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film with a water contact angle of 29° on both main surfaces, and a metal-clad laminate was produced in the same manner as in Example 1, except that the thicknesses of the first heat-sealed resin layer and the second heat-sealed resin layer were changed. This thermosetting polyimide film was obtained by subjecting a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-VT) to discharge treatment. For this discharge treatment, a discharge amount of 155 W·min / m was used. 2 The corona discharge treatment was performed with the setting set at 100° C. The film and the copper foil were thermocompression-bonded using the same double belt press as in Example 1. The physical properties of each layer and the thermocompression-bonding conditions are shown in Table 2.

[0072] Comparative Example 3 In Comparative Example 3, the thermosetting polyimide layer of the insulating layer was made of a thermosetting polyimide film having a water contact angle of 79.5° on both main surfaces, and a metal-clad laminate was manufactured in the same manner as in Example 1, except that the thicknesses of the first heat-sealed resin layer and the second heat-sealed resin layer were changed. This thermosetting polyimide film was a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-SGA). The same double belt press machine as in Example 1 was used in the process of thermocompression bonding the film and the copper foil. The physical properties of each layer and the conditions of thermocompression bonding are shown in Table 2.

[0073] Comparative Example 4 In Comparative Example 4, a metal-clad laminate was produced in the same manner as in Example 1, except that the thermosetting polyimide layer of the insulating layer was composed of a thermosetting polyimide film having a water contact angle of 76° on both main surfaces. This thermosetting polyimide film was a commercially available thermosetting polyimide film (manufactured by Ube Industries, Ltd., product name: Upilex-S). The same double belt press machine as in Example 1 was used in the step of thermocompression bonding the film and the copper foil. The physical properties of each layer and the conditions for thermocompression bonding are shown in Table 2.

[0074] <Appearance inspection> A 500mm x 500mm sample was taken from the metal-clad laminate obtained in each example, and the appearance of the sample was visually observed. Samples without wrinkles were judged as good (○), and samples with wrinkles were judged as bad (×). The results are shown in the "Appearance Inspection" column in Tables 1 and 2.

[0075] <Peel strength> The metal-clad laminate obtained in each example was cut into strips with a width of 10 mm to prepare samples, and the peel strength between the thermosetting polyimide layer and the heat-sealed resin layer was measured using "Method A" (90° peel method) specified in JIS C6471. A peel strength value of 0.6 N / mm or more was judged as good (○), and a value of less than 0.6 N / mm was judged as poor (×). The results are shown in the "Peel Strength" column in Tables 1 and 2.

[0076] <High frequency transmission characteristics> A sample was prepared by etching the metal layer of each metal-clad laminate to form a microstrip line with a circuit length of 100 mm and an impedance of 50 Ω. The insertion loss (S21) of this sample at 40 GHz was measured using a network analyzer (Keysight Technologies, Inc., product name: E8363B).

[0077] When the absolute value of the insertion loss (S21) was less than 0.4 dB / cm, the high frequency transmission characteristics were judged to be good (○), when it was 0.4 dB / cm or more but less than 0.5 dB / cm, the high frequency transmission characteristics were judged to be slightly poor (△), and when it was 0.5 dB / cm or more, the high frequency transmission characteristics were judged to be poor (×). The results are shown in the "High Frequency Transmission Characteristics" column in Tables 1 and 2.

[0078] [Table 1]

[0079] [Table 2] As shown in Table 1, it is understood that good evaluation results are obtained for the peel strength between the thermosetting polyimide layer and the heat-sealable resin layer in Examples 1 to 6. Moreover, it is understood that good evaluation results are also obtained for the high-frequency transmission characteristics in Examples 1 to 5, since the metal layer is formed using a metal foil having a main surface with high smoothness.

[0080] On the other hand, as shown in Comparative Examples 1 to 4, when a thermosetting polyimide film having a water contact angle of more than 20° is used, good evaluation results cannot be obtained for the peel strength between the thermosetting polyimide layer and the heat-sealable resin layer. [Explanation of symbols]

[0081] 11...Metal clad laminate 12...Insulating layer 13...Metal layer 21...Thermosetting polyimide layer 31...Heat-sealing resin layer 111...Laminate 113...Metal foil 121...Thermosetting polyimide film 131...Thermoplastic resin film

Claims

1. An insulating layer and a metal layer laminated on one or both sides of the insulating layer, a method for producing a metal-clad laminate, the method comprising the steps of: producing a metal-clad laminate comprising: a thermosetting polyimide layer; and a heat-sealed resin layer provided between the thermosetting polyimide layer and the metal layer; and producing a metal-clad laminate, the metal-clad laminate being made of a thermosetting polyimide film having a water contact angle of 20° or less on a main surface bonded to the heat-sealed resin layer, the method comprising the steps of: A step of preparing a thermosetting polyimide film, a metal foil that will become the metal layer, and a thermoplastic resin film that will become the heat-sealable resin layer; a step of forming a treated surface by subjecting only the main surface of the thermosetting polyimide film to a discharge treatment so as to have a water contact angle of 20° or less, without subjecting the main surface of the thermoplastic resin film to a treatment for reducing the water contact angle; and a step of thermocompressing, using a double belt press device, the laminate in which the thermoplastic resin film is disposed between the thermosetting polyimide film having the treated surface formed thereon and the metal foil, with the main surface of the thermoplastic resin film being superimposed on the treated surface of the thermosetting polyimide film.

2. The method for manufacturing a metal-clad laminate described in claim 1, wherein the maximum temperature in the thermocompression bonding process is Tm+70°C or lower, where Tm is the melting point of the thermoplastic resin film.

3. 3. The method for producing a metal-clad laminate according to claim 1, wherein the thermosetting polyimide layer contains 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as copolymerization components.

4. The method for producing a metal-clad laminate according to claim 1 , wherein the heat-sealing resin layer has a melting point of 280° C. or higher.

5. The method for producing a metal-clad laminate according to any one of claims 1 to 4, wherein the metal foil is composed of a metal foil having a ten-point average roughness (Rzjis) of 2.0 or less on a main surface to be bonded to the heat-sealable resin layer.

6. The method for producing a metal-clad laminate according to claim 1 , wherein the thermosetting polyimide layer has a linear expansion coefficient in the range of 10 ppm / K or more and 26 ppm / K or less.

7. The method for producing a metal-clad laminate according to claim 1 , wherein the thermal adhesive resin layer has a water absorption rate lower than a water absorption rate of the thermosetting polyimide layer.

8. The method for producing a metal-clad laminate according to claim 1 , wherein an interlayer peel strength between the thermosetting polyimide layer and the heat-sealable resin layer is 0.6 N / mm or more.

9. The method for producing a metal-clad laminate according to claim 1 , wherein the heat-sealing resin layer is made of a fluorine-based resin.

10. In a surface analysis of the thermosetting polyimide film using X-ray photoelectron spectroscopy, the following formula (1): R=A2 / A1...(1) The method for producing a metal-clad laminate according to any one of claims 1 to 9, wherein a ratio R calculated by the above formula is 1.35 or more.

11. In a surface analysis of the thermosetting polyimide film using X-ray photoelectron spectroscopy, the sum of the integrated values ​​of 278 to 298 eV, 391 to 411 eV, 523 to 543 eV, and 94 to 114 eV was taken as 100%, and the proportion of the integrated value of 523 to 543 eV in the total 100% was taken as the content of oxygen atoms. The oxygen atom content B1 (%) before the discharge treatment and the oxygen atom content B2 (%) after the discharge treatment are used to calculate the following formula (2): C (%)=B2-B1...(2) The method for producing a metal-clad laminate according to any one of claims 1 to 10, wherein a change C (%) of oxygen atoms calculated by the above formula is 5% or more.

12. The method for producing a metal-clad laminate according to any one of claims 1 to 11, wherein the discharge treatment is at least one selected from a corona discharge treatment, an atmospheric plasma discharge treatment, and a vacuum plasma discharge treatment.

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