METAL CLAD LAMINATE MANUFACTURING METHOD AND CIRCUIT BOARD MANUFACTURING METHOD

Abstract

To provide a manufacturing method of a metal-clad laminate that has low polarity as an adhesive layer, and even when a material having low dielectric property is used, can improve adhesion between an insulation resin layer and the adhesive layer.SOLUTION: A method for manufacturing a metal-clad laminate that comprises a metal layer M1, an insulating resin layer R1, and an adhesive layer B, the method comprises heat treatment of heating with an adhesive sheet BS serving as the adhesive layer B in contact with the insulating resin layer R1, and a value obtained by subtracting an adhesion temperature of adhesive layer B from the heat treatment temperature T at a certain point in a heat treatment process and integrating it over a total process time tA of the heat treatment process is 50 [unit: °C. h] or more.SELECTED DRAWING: Figure 1C

Description

[Technical Field]

[0001] The present invention relates to a method for producing a metal-clad laminate useful as a material for electronic components, and a method for producing a circuit board. [Background technology]

[0002] In recent years, with the progress in miniaturization, weight reduction, and space-saving of electronic devices, there has been an increasing demand for flexible printed circuits (FPCs), which are thin, lightweight, flexible, and have excellent durability even when repeatedly bent. Because FPCs allow for three-dimensional, high-density packaging even in limited spaces, their applications are expanding to include wiring for electronic devices such as hard disk drives, DVDs, and smartphones, as well as components such as cables and connectors.

[0003] In addition to the aforementioned trend toward higher density, the advancement of device performance has created a need for support for higher transmission signal frequencies. When transmitting high-frequency signals, if transmission loss along the transmission path is significant, problems such as electrical signal loss and longer signal delay times occur. Therefore, reducing transmission loss will become increasingly important in future FPCs. To support high-frequency signal transmission, FPCs are increasingly using liquid crystal polymers, which have lower dielectric constants and dielectric loss tangents, as their dielectric layers, instead of the commonly used polyimide. However, while liquid crystal polymers have excellent dielectric properties, there is still room for improvement in their heat resistance and adhesion to metal layers. Increasing the thickness of the dielectric layer is also important for reducing transmission loss.

[0004] Therefore, Patent Documents 1 and 2 propose a configuration in which a polyimide layer and an adhesive layer with low dielectric properties are laminated to reduce the dielectric constant, dielectric loss tangent, and thickness of the dielectric layer. However, in the configurations described in Patent Documents 1 and 2, the adhesive layer has low polarity, leaving room for improvement in the adhesion between the polyimide layer and the adhesive layer. Similarly, Patent Document 3 employs a configuration in which a polyimide and an adhesive film with low dielectric properties are laminated as the dielectric layer, but does not mention the adhesion between the polyimide and the dielectric layer. Patent Document 4 considers a configuration in which a polyimide and an epoxy adhesive are laminated, but uses a surface-treated polyimide film, which ensures adhesion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-170417 [Patent Document 2] Japanese Patent Application Publication No. 2020-55299 [Patent Document 3] Patent No. 6936639 [Patent Document 4] Patent Publication No. 2021-72324 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide a method for manufacturing a metal-clad laminate that can improve adhesion between an insulating resin layer and an adhesive layer without requiring additional steps to improve adhesion, such as surface treatment, even when a material with low polarity and low dielectric properties is used as the adhesive layer, and to provide a metal-clad laminate obtained by the manufacturing method that has high interlayer adhesion and excellent dielectric properties. [Means for solving the problem]

[0007] In the past, when laminating an insulating resin layer and an adhesive layer, the heat treatment was generally completed when the curing reaction of the resin constituting the adhesive layer had progressed completely. However, the inventors' research has made it possible to obtain a metal-clad laminate with high interlayer adhesion by considering the relationship between the maximum temperature in the heat treatment process and the curing temperature of the adhesive layer, and further by considering the time integral value of the difference between the heat treatment temperature and the adhesive temperature of the adhesive layer.

[0008] That is, the method for manufacturing a metal-clad laminate according to a first aspect of the present invention is a method for manufacturing a metal-clad laminate comprising a first metal layer, a first insulating resin layer laminated on one side of the first metal layer, and an adhesive layer laminated on the first insulating resin layer. A method for producing a metal-clad laminate according to a first aspect of the present invention includes a heat treatment step of heating the first insulating resin layer in a state where the adhesive sheet that will become the adhesive layer is in contact with the first insulating resin layer, The maximum temperature in the heat treatment step is in the range of the curing temperature of the adhesive layer or higher and the curing temperature + 50°C or lower.

[0009] A second aspect of the present invention is a method for producing a metal-clad laminate comprising a first metal layer, a first insulating resin layer laminated on one side of the first metal layer, an adhesive layer laminated on the first insulating resin layer, a second insulating resin layer laminated on the adhesive layer, and a second metal layer laminated on the second insulating resin layer. A method for producing a metal-clad laminate according to a second aspect of the present invention includes a heat treatment step of heating an adhesive sheet that will become the adhesive layer in contact with the first insulating resin layer, or with both the first insulating resin layer and the second insulating resin layer, The maximum temperature in the heat treatment step is in the range of the curing temperature of the adhesive layer or higher and the curing temperature + 50°C or lower.

[0010] A third aspect of the present invention provides a method for producing a metal-clad laminate comprising a first metal layer, a first insulating resin layer laminated on one side of the first metal layer, an adhesive layer laminated on the first insulating resin layer, a second insulating resin layer laminated on the adhesive layer, and a second metal layer laminated on the second insulating resin layer. A third aspect of the present invention provides a method for producing a metal-clad laminate, comprising: a coating film forming step of applying a solution of a resin composition that will become the adhesive layer to the second insulating resin layer and drying the applied coating film; a heat treatment step of heating the first insulating resin layer in a state where the first insulating resin layer is in contact with the coating film; The maximum temperature in the heat treatment step is in the range of the curing temperature of the adhesive layer or higher and the curing temperature + 50°C or lower.

[0011] The method for producing a metal-clad laminate according to the first to third aspects of the present invention is to calculate a difference (unit: ° C.) obtained by subtracting the adhesive temperature of the adhesive layer from the heat treatment temperature T at a certain point in the heat treatment step over a total process time t A The adhesive temperature is characterized by a value integrated over a period of 50°C / h (unit: h). (Here, the adhesive temperature refers to a temperature above the glass transition temperature in the loss modulus-temperature curve obtained by measuring the dynamic viscoelasticity of the adhesive layer, and is a temperature that is 22% higher than the temperature at which the tangent slope of the curve first becomes -7 kPa / °C in the higher temperature range.)

[0012] In the methods for manufacturing metal-clad laminates according to the first to third aspects of the present invention, the heat treatment temperature in the heat treatment step may be constant or may be changed stepwise multiple times, and the relationship between the heat treatment temperature and the heat treatment time may satisfy the following mathematical formula (1):

[0013]

number

[0014] In formula (1), T 1i[unit: °C] is the difference obtained by subtracting the adhesive temperature of the adhesive layer from the i-th heat treatment temperature, and t i is the i-th heat treatment time [unit: h], and n is an integer of 1 or more.

[0015] In the methods for producing a metal-clad laminate according to the first to third aspects of the present invention, at least the heat treatment step may be carried out in a state where the laminate is wound in a roll shape.

[0016] In the methods for manufacturing a metal-clad laminate according to the first to third aspects of the present invention, the peel strength between the adhesive layer and the first insulating resin layer in the metal-clad laminate may be 0.7 kN / m or more.

[0017] In the method for producing a metal-clad laminate according to the first to third aspects of the present invention, the adhesive layer may contain a polyimide containing an acid dianhydride residue derived from an acid dianhydride component and a diamine residue derived from a diamine component, The polyimide may contain 20 mol % or more of diamine residues derived from a dimer diamine composition containing, as a main component, a dimer diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid with primary aminomethyl groups or amino groups, relative to the total diamine residues.

[0018] In the methods for producing a metal-clad laminate according to the first to third aspects of the present invention, the first insulating resin layer may contain a polyimide containing an acid dianhydride residue derived from an acid dianhydride component and a diamine residue derived from a diamine component, The number of polar groups per repeating unit of the acid anhydride residue and diamine residue contained in the first insulating resin layer may be less than eight.

[0019] The method for producing a circuit board of the present invention includes a step of processing one or both of the first metal layer and the second metal layer in a metal-clad laminate produced by any of the above methods into wiring. [Effects of the Invention]

[0020] The method of the present invention can improve the adhesion between the insulating resin layer and the adhesive layer at a relatively low heat treatment temperature without requiring additional processes such as surface treatment to improve adhesion, even when using materials with low polarity and low dielectric properties, and can provide a metal-clad laminate that does not cause changes in physical properties such as decomposition even for materials with low curing temperatures.The metal-clad laminate obtained by the method of the present invention can reduce the transmission loss of high-frequency signals and can also suppress interlayer delamination during circuit processing such as drilling and cutting, so that when applied to circuit boards that transmit high-frequency signals of 10 GHz or more, for example, transmission loss can be reduced and reliability can be improved. [Brief explanation of the drawings]

[0021] [Figure 1A] 1A to 1C are explanatory views of main steps of a method for manufacturing a metal-clad laminate according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is an explanatory diagram of a step following FIG. 1A. [Figure 1C] FIG. 1C is an explanatory diagram of a step following FIG. 1B. [Figure 2A] FIG. 6 is an explanatory diagram of main steps of a method for manufacturing a metal-clad laminate according to a second embodiment of the present invention. [Figure 2B] FIG. 2B is an explanatory diagram of a step following FIG. 2A. [Figure 2C] FIG. 2C is an explanatory diagram of a step following FIG. 2B. [Figure 3A] FIG. 10 is an explanatory diagram of main steps of a method for manufacturing a metal-clad laminate according to a third embodiment of the present invention. [Figure 3B] FIG. 3B is an explanatory diagram of a step following FIG. 3A. [Figure 3C] FIG. 3C is an explanatory diagram of a step following FIG. 3B. [Figure 3D] FIG. 3D is an explanatory diagram of a step following FIG. 3C. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings.

[0023] [First embodiment] 1A, 1B, and 1C are explanatory diagrams showing main steps of a method for manufacturing a metal-clad laminate according to a first embodiment of the present invention. As shown in FIG. 1C, this embodiment produces a metal-clad laminate C having a layer structure in which a metal layer M1, an insulating resin layer R1, and an adhesive layer B are laminated in this order. A This is a method for manufacturing the above. The detailed configurations of the metal layer M1, the insulating resin layer R1, and the adhesive layer B will be described later.

[0024] (Intermediate laminate formation process) 1A, an adhesive sheet BS, which will become the adhesive layer B, is attached to the insulating resin layer R1, and the insulating resin layer R1 and the adhesive sheet BS are laminated in contact with each other to form an intermediate laminate S. In this step, temporary pressure bonding is preferably performed at a pressure in the range of 0.1 to 1 MPa, for example. The resin constituting the adhesive sheet BS is preferably in an uncured or semi-cured state. Here, "semi-cured" means that the tensile modulus of the adhesive sheet BS is higher than before the heat treatment, and that the tensile modulus has not yet increased even with continued heat treatment. The insulating resin layer R1 can be a first single-sided metal-clad laminate C1 formed by previously laminating a metal layer M1. The adhesive sheet BS can be produced, for example, by applying a solution of the resin composition that will become the adhesive layer B to any supporting substrate, drying it, and then peeling it off from the supporting substrate to obtain the adhesive sheet BS. The method for applying the solution of the resin composition that will become the adhesive layer B to the supporting substrate is not particularly limited, and it is possible to apply it using, for example, a coater such as a comma, die, knife, or lip coater.

[0025] The configuration of the first single-sided metal-clad laminate C1 is not particularly limited, and common FPC materials can be used, including commercially available copper-clad laminates. For example, commercially available copper-clad laminates include R-F705T (product name) manufactured by Panasonic Corporation and ESPANEX (product name) manufactured by Nippon Steel Chemical & Material Co., Ltd. The method for forming the first single-sided metal-clad laminate C1 is not particularly limited, and the laminate may be manufactured by thermocompression bonding a metal foil that will become the metal layer M1 and a resin film that will become the insulating resin layer R1, or by applying a solution of a resin composition (including a solution of a precursor composition) that will become the insulating resin layer R1 onto a metal foil that will become the metal layer M1 to form a coating film, followed by drying, solidifying, or curing the coating film.

[0026] (Heat treatment process) In this step, as shown in FIG. 1B, the intermediate laminate S is heated. This heat treatment hardens the resin that constitutes the adhesive sheet BS to form an adhesive layer B, and the metal-clad laminate C A Here, the curing temperature CT of adhesive layer B B "C" is the temperature at which the resin constituting the adhesive sheet BS or the coating film AA cures (including cross-linking) to form the adhesive layer B, and is specifically defined as the temperature 25% higher than the temperature at which the complex viscosity is minimized when measured using a rheometer at a heating rate of 5°C / min and an angular frequency of 6.28 rad / s, as shown in the Examples below. Temperature control in the heat treatment step will be described in detail later. The heat treatment step can be carried out, for example, by A) a method in which the intermediate laminate S is wound into a roll, placed in a thermostatic chamber, and heat-treated for a predetermined time and temperature (Method A), or B) a method in which the intermediate laminate S is flowed by a roll-to-roll method and heat-treated for a predetermined time and temperature (Method B). Either method may be used in the present embodiment, but when the intermediate laminate S is wound into a roll and heat-treated, it is preferable to attach a release material to the surface of the adhesive layer B to prevent adhesion between the adhesive layer B and the metal layer M1.

[0027] (Modification of the first embodiment) As a modification of the first embodiment, although not shown in the drawings, the intermediate laminate formation step and the heat treatment step can be performed simultaneously. That is, an adhesive sheet BS, which will become the adhesive layer B, is attached to the insulating resin layer R1, and the insulating resin layer R1 and the adhesive sheet BS are thermocompressed together for a predetermined time (thermocompression bonding step). In this way, by performing the heat treatment simultaneously with the lamination without using the intermediate laminate S, the resin that makes up the adhesive sheet BS is hardened to form the adhesive layer B, and the metal-clad laminate C is formed. A In this case, the heat treatment conditions in the thermocompression bonding step are the same as those in the above-mentioned heat treatment step. The pressure in the thermocompression bonding step can be appropriately set depending on the materials of the insulating resin layer R1 and the adhesive layer B, but is preferably in the range of 0.1 to 1 MPa, and more preferably in the range of 0.1 to 0.5 MPa.

[0028] In this embodiment, the intermediate laminate formation step is preferably carried out by a roll-to-roll method, which can improve productivity.

[0029] [Second embodiment] 2A, 2B, and 2C are explanatory diagrams showing main steps of a method for manufacturing a metal-clad laminate according to a second embodiment of the present invention. As shown in FIG. 2C, this embodiment is directed to a metal-clad laminate C having a layer structure in which a metal layer M1, an insulating resin layer R1, an adhesive layer B, an insulating resin layer R2, and a metal layer M2 are laminated in this order. B This is a method for manufacturing the above. The detailed configurations of the metal layers M1 and M2, the insulating resin layers R1 and R2, and the adhesive layer B will be described later.

[0030] (Intermediate laminate formation process) In this step, an adhesive sheet BS, which will become adhesive layer B, is attached to at least insulating resin layer R1, and insulating resin layer R1 and adhesive sheet BS are laminated in contact with each other to form intermediate laminate S. In this step, as shown in Fig. 2A, it is preferable to attach adhesive sheets BS, which will become adhesive layer B, to both insulating resin layer R1 and insulating resin layer R2 to form intermediate laminate S. In this step, it is preferable to perform temporary pressure bonding at a pressure in the range of 0.1 to 1 MPa, for example. Here, the adhesive sheet BS can be the same as that in the first embodiment. The insulating resin layer R1 can be a first single-sided metal-clad laminate C1 formed by previously laminating a metal layer M1. The insulating resin layer R2 can also be a second single-sided metal-clad laminate C2 formed by previously laminating a metal layer M2. The first single-sided metal-clad laminate C1 and the second single-sided metal-clad laminate C2 can be the same as the first single-sided metal-clad laminate C1 in the first embodiment. The first single-sided metal-clad laminate C1 and the second single-sided metal-clad laminate C2 can have the same or different configurations.

[0031] (Heat treatment process) In this step, as shown in FIG. 2B, the intermediate laminate S is heated. This heat treatment hardens the resin that constitutes the adhesive sheet BS to form the adhesive layer B, and the metal-clad laminate C B The temperature control in the heat treatment step will be described in detail later. The heat treatment step can be carried out by the same method A, method B, etc. as in the first embodiment.

[0032] (Modification of the second embodiment) As a modification of the second embodiment, although not shown in the drawings, the intermediate laminate formation step and the heat treatment step can be performed simultaneously. That is, an adhesive sheet BS that will become the adhesive layer B is attached to at least the insulating resin layer R1 (preferably to both the insulating resin layer R1 and the insulating resin layer R2), and the insulating resin layer R1 and the adhesive sheet BS are thermocompressed together for a predetermined time while in contact with each other (thermocompression bonding step). In this way, by performing the heat treatment simultaneously with the lamination without using the intermediate laminate S, the resin that makes up the adhesive sheet BS is hardened to form the adhesive layer B, and the metal-clad laminate C is formed. B In this case, the heat treatment conditions in the thermocompression bonding step are the same as those in the above-mentioned heat treatment step. The pressure in the thermocompression bonding step can be appropriately set depending on the materials of the insulating resin layers R1, R2 and the adhesive layer B, but is preferably in the range of 0.1 to 1 MPa, and more preferably in the range of 0.1 to 0.5 MPa.

[0033] In this embodiment, the intermediate laminate formation step is preferably carried out by a roll-to-roll method, which can improve productivity.

[0034] [Third embodiment] 3A, 3B, 3C, and 3D are explanatory diagrams showing main steps of a method for manufacturing a metal-clad laminate according to a third embodiment of the present invention. As shown in FIG. 3D, this embodiment is directed to a metal-clad laminate C having a layer structure in which a metal layer M1, an insulating resin layer R1, an adhesive layer B, an insulating resin layer R2, and a metal layer M2 are laminated in this order. B This is a method for manufacturing the above. The detailed configurations of the metal layer M1, the metal layer M2, the insulating resin layer R1, the insulating resin layer R2, and the adhesive layer B will be described later.

[0035] (Coating film formation process) In this step, as shown in FIG. 3A, a solution of a resin composition is applied to the insulating resin layer R2 and then dried to form a coating film AA that will become the adhesive layer B. The resin composition solution may be, for example, a solution of the resin that will form the adhesive layer B or a solution of its precursor. There are no particular limitations on the method for applying the solution of the resin composition that will become the adhesive layer B onto the insulating resin layer R2, and it is possible to apply it using, for example, a coater such as a comma, die, knife, or lip. The insulating resin layer R2 can be a second single-sided metal-clad laminate C2 formed by previously laminating a metal layer M2 on the insulating resin layer R2. The method for forming the single-sided metal-clad laminate C2 is the same as that in the second embodiment.

[0036] (Intermediate laminate formation process) 3B, the insulating resin layer R1 is bonded to the coating film AA to form an intermediate laminate S in which the insulating resin layer R1 and the coating film AA are laminated in contact with each other. In this step, temporary pressure bonding is preferably performed at a pressure in the range of 0.1 to 1 MPa, for example. The resin constituting the coating film AA is preferably in an uncured or semi-cured state, where semi-cured means a state in which the tensile modulus of the coating film AA is higher than that before the heat treatment and the increase in the tensile modulus cannot be confirmed even if the heat treatment is continued. The insulating resin layer R1 can be a first single-sided metal-clad laminate C1 formed by laminating a metal layer M1 in advance. The method for forming the first single-sided metal-clad laminate C1 is the same as in the first and second embodiments.

[0037] (Heat treatment process) In this step, as shown in FIG. 3C, the intermediate laminate S is heated. This heat treatment hardens the resin constituting the coating film AA to form the adhesive layer B, and the metal-clad laminate C B The details of the temperature control in the heat treatment step will be described later. When the heat treatment is carried out by the roll-to-roll method, the heat treatment step can be carried out by the same method A, method B, etc. as in the first embodiment.

[0038] (Modification of the third embodiment) As a modified example of the third embodiment, although not shown in the drawings, the intermediate laminate formation step and the heat treatment step can be performed simultaneously. That is, the coating film AA that will become the adhesive layer B is attached to the insulating resin layer R1, and the insulating resin layer R1 and the coating film AA are thermocompressed together for a predetermined time while in contact with each other (thermocompression bonding step). In this way, by performing the heat treatment simultaneously with the lamination without using the intermediate laminate S, the resin that makes up the coating film AA is hardened to form the adhesive layer B, and the metal-clad laminate C is formed. B In this case, the heat treatment conditions in the thermocompression bonding step are the same as those in the above-mentioned heat treatment step. The pressure in the thermocompression bonding step can be appropriately set depending on the materials of the insulating resin layer R1 and the coating film AA (adhesive layer B), but is preferably in the range of 0.1 to 1 MPa, and more preferably in the range of 0.1 to 0.5 MPa.

[0039] In this embodiment, the intermediate laminate formation step is preferably carried out by a roll-to-roll method, which can improve productivity.

[0040] [Maximum temperature during heat treatment process] In the first to third embodiments, the maximum temperature Tmax in the heat treatment step is set within a range of not less than the curing temperature of adhesive layer B but not more than the curing temperature + 50° C. If the heat treatment is performed within this range, excessive heat treatment of the first insulating resin layer (or the second insulating resin layer) can be suppressed, and deterioration of the dielectric loss tangent and thermal decomposition can be prevented.

[0041] [Temperature and time in the heat treatment process] In the first to third embodiments, in the heat treatment process, at a certain time t0, the heat treatment temperature T is changed to the adhesive temperature T B The difference T1 [unit: °C] obtained by subtracting A The value X, integrated over [unit: time], is controlled to be 50 or more, preferably 100 or more. If the heat treatment temperature and time satisfy this condition, sufficient adhesion between the layers is achieved. If the value X is less than 50, the heat treatment temperature or time is too short, resulting in insufficient interface formation by molecular diffusion and poor adhesion between the layers. On the other hand, if the value X is too large, it may cause decomposition of the adhesive layer B or a deterioration in the dielectric properties of the insulating resin layer R1. Therefore, the upper limit of the value X is preferably 20,000, more preferably 10,000. Here, the bonding temperature means a temperature above the glass transition temperature in the loss modulus-temperature curve obtained by measuring the dynamic viscoelasticity of the adhesive layer B, the temperature being 22% higher than the temperature at which the tangent slope of the curve first becomes -7 kPa / °C. The inventors of the present application focused on the temperature above the glass transition temperature of the adhesive layer B at which the rate of decrease in the loss modulus is lowest, i.e., the temperature at which the tangent slope of the loss modulus-temperature curve first becomes -7 kPa / °C, and based on knowledge of the correlation between adhesive strength and value X, defined the bonding temperature as the temperature being 22% higher than the temperature at which the tangent slope first becomes -7 kPa / °C.

[0042] The "heat treatment temperature" refers to the atmospheric temperature during the heat treatment.

[0043] As an example of a simple method for controlling the heat treatment temperature in the heat treatment step, (i) when the heat treatment temperature is constant, or (ii) when the heat treatment temperature is changed stepwise multiple times, it is preferable that the relationship between the heat treatment temperature and the heat treatment time satisfy the following mathematical formula (1):

[0044]

number

[0045] In formula (1), T 1i [unit: °C] is the temperature T B is the difference obtained by subtracting t i is the i-th heat treatment time [unit: h], and n is an integer of 1 or more.

[0046] In the heat treatment process, when a) the heat treatment temperature is constant, or b) the heat treatment temperature is changed stepwise multiple times, the adhesion between layers is sufficiently exhibited as long as the heat treatment temperature and time satisfy the formula (1). a) The i-th heat treatment temperature and the adhesive temperature T of adhesive layer B B Difference T 1i and, b) the i-th heat treatment time t i and, The total value X1 obtained by adding up the products of these for the number of times is equal to or greater than 50, and preferably equal to or greater than 100. If the total value X1 is less than 50, the heat treatment temperature or time is too short, resulting in insufficient interface formation by molecular diffusion and poor adhesion between the layers. The upper limit of the total value X1 is the same as the value X.

[0047] In a heat treatment process that satisfies the above relationship, crosslinking or thermal curing can be promoted regardless of whether the resin constituting adhesive layer B is a thermoplastic resin that forms crosslinks by heat or a thermosetting resin. The heat treatment temperature is the adhesive temperature T B By setting the heat treatment time to be longer than the time required for curing of the adhesive layer B, molecular diffusion from the adhesive layer B to the insulating resin layer R1 (preferably both insulating resin layers R1 and R2) is promoted, and molecular chains become entangled across the layer boundary, which contributes to improving the adhesion between the insulating resin layer R1 (preferably both insulating resin layers R1 and R2) and the adhesive layer B. That is, in the loss modulus-temperature curve obtained by measuring the dynamic viscoelasticity of the adhesive layer B, when the temperature exceeds the glass transition temperature and exceeds a temperature that is 22% higher than the temperature at which the slope of the tangent to the curve first becomes -7 kPa / °C in the higher temperature range, the molecular chain motion of the resin constituting the adhesive layer B becomes more active, and entanglement with the molecular chains of the resin constituting the insulating resin layer R1 is more likely to occur.

[0048] The maximum processing temperature in the heat treatment process can be appropriately determined depending on the materials of the insulating resin layer R1 and the adhesive layer B, whether heat treatment alone is performed or thermocompression bonding is performed. However, for example, taking into account the heat resistance of the adhesive layer B, it is preferable to perform the heat treatment at a temperature higher than the bonding temperature of the adhesive layer B, preferably at +50°C or lower, more preferably at +30°C or lower.

[0049] [Configuration of metal clad laminate] The metal-clad laminate C manufactured as described above A ,C B The configuration will be explained.

[0050] (metal layer) The material of the metal layer M1 and the metal layer M2 is not particularly limited, but examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or a copper alloy is particularly preferred. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is also the same as that of the metal layer M1 and the metal layer M2.

[0051] The thickness of the metal layer M1 and the metal layer M2 is not particularly limited, but when a metal foil such as copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Furthermore, commercially available copper foil may be used as the copper foil.

[0052] The metal foil may be subjected to a surface treatment using, for example, siding, aluminum alcoholate, aluminum chelate, or a silane coupling agent for the purpose of, for example, rust prevention or improving adhesive strength.

[0053] (insulating resin layer) The insulating resin layers R1 and R2 are not particularly limited as long as they are made of a resin having electrical insulation properties, and examples thereof include polyimide, liquid crystal polymer, epoxy resin, phenolic resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, ETFE, etc., but are preferably made of polyimide. Note that in the present invention, the term "polyimide" refers to a resin made of a polymer having an imide group in its molecular structure, such as polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, or polybenzimidazoleimide.

[0054] The insulating resin layer R1 and the insulating resin layer R2 are not limited to a single layer, but may be a laminate of multiple resin layers, and preferably include a non-thermoplastic polyimide layer made of a non-thermoplastic polyimide. Note that "non-thermoplastic polyimide" generally refers to a polyimide that does not soften or exhibit adhesiveness even when heated. In the present invention, however, a non-thermoplastic polyimide having a storage modulus of 1.0 × 10 at 30°C measured using a dynamic viscoelasticity measuring device (DMA) is used. 9 Pa or more, and the storage modulus at 300°C is 3.0 × 10 8 This refers to polyimides with a modulus of tensile strength of 100 Pa or more.

[0055] The insulating resin layers R1 and R2 can be selected from, for example, commercially available polyimide films, commercially available liquid crystal polymer films, or resins used as insulating substrates in commercially available metal-clad laminates. Examples of polyimide films that can be used include UPILEX (trade name) manufactured by Ube Industries, Ltd., Kapton (trade name) manufactured by Toray DuPont Co., Ltd., and Apical (trade name) and Pixio (trade name) manufactured by Kaneka Corporation. Examples of liquid crystal polymer films that can be used include Vecstar (trade name) manufactured by Kuraray Co., Ltd. and BIAC Film (trade name) manufactured by Primatec Co., Ltd.

[0056] The coefficient of thermal expansion (CTE) of the insulating resin layer R1 and the insulating resin layer R2 is not particularly limited, but is preferably 10 ppm / K or more, more preferably in the range of 10 ppm / K to 30 ppm / K, and even more preferably in the range of 15 ppm / K to 25 ppm / K. If the CTE is less than 10 ppm / K or more than 30 ppm / K, warping may occur or dimensional stability may decrease. The desired CTE can be controlled by appropriately changing the combination of raw materials used, the thickness, and the drying and curing conditions.

[0057] When the insulating resin layers R1 and R2 are applied to, for example, a circuit board, the dielectric loss tangent (Tan δ) at 10 GHz is preferably 0.02 or less, more preferably 0.0005 to 0.01, and even more preferably 0.001 to 0.008, in order to suppress deterioration of dielectric loss. If the dielectric loss tangent at 10 GHz exceeds 0.02, problems such as loss of electrical signals are likely to occur in the transmission path of high-frequency signals when applied to a circuit board. On the other hand, the lower limit of the dielectric loss tangent at 10 GHz is not particularly limited, but consideration is given to controlling the physical properties as an insulating resin layer of a circuit board.

[0058] When the insulating resin layers R1 and R2 are used as insulating resin layers for a circuit board, for example, the dielectric constant (ε) at 10 GHz is preferably 4.0 or less to ensure impedance matching. If the dielectric constant at 10 GHz exceeds 4.0, the insulating resin layers will have a higher dielectric loss when used in a circuit board, which may lead to problems such as loss of electrical signals on the transmission path of high-frequency signals.

[0059] <Preferable Configuration of Insulating Resin Layer> Polyimide is suitable for the insulating resin layers R1 and R2 from the viewpoints of heat resistance, dimensional stability, and chemical resistance. Furthermore, from the viewpoint of adhesion to the metal layer, a configuration in which a thermoplastic polyimide is provided between the metal layer and the non-thermoplastic polyimide film is preferred. The term "thermoplastic polyimide" generally refers to a polyimide whose glass transition temperature (Tg) can be clearly confirmed. In the present invention, however, a polyimide having a storage modulus of 1.0×10 at 30°C measured using DMA is used. 8 Pa or more, and the storage modulus at 300°C is 3.0 × 10 7 It refers to a polyimide having a modulus of less than 1 Pa. In addition, a thermoplastic polyimide may or may not be present between the non-thermoplastic polyimide and adhesive layer B.

[0060] Non-thermoplastic polyimide layer: The non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer contains a tetracarboxylic acid residue and a diamine residue. In the present invention, the tetracarboxylic acid residue refers to a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue refers to a divalent group derived from a diamine compound. The polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine.

[0061] (tetracarboxylic acid residue) The non-thermoplastic polyimide preferably contains tetracarboxylic acid residues derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA). Tetracarboxylic acid residues derived from BPDA tend to form an ordered polymer structure, suppressing molecular motion and reducing the dielectric loss tangent and moisture absorption. Furthermore, tetracarboxylic acid residues derived from PMDA are highly planar and rigid, reducing the CTE of the polyimide and increasing the glass transition temperature (Tg).

[0062] (diamine residue) The diamine residue contained in the non-thermoplastic polyimide is preferably a diamine residue derived from a diamine compound represented by general formula (1).

[0063] [ka]

[0064] In general formula (1), the linking group Z represents a single bond or -COO-; Y independently represents a monovalent hydrocarbon having 1 to 3 carbon atoms, which may be substituted with a halogen atom or a phenyl group, or an alkoxy group having 1 to 3 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkenyl group; n represents an integer of 0 to 2; and p and q independently represent integers of 0 to 4. Here, "independently" means that in general formula (1), the multiple substituents Y and the integers p and q may be the same or different. In general formula (1), the hydrogen atoms in the two terminal amino groups may be substituted, for example, with -NR2R3 (where R2 and R3 independently represent any substituent such as an alkyl group).

[0065] The diamine compound represented by general formula (1) (hereinafter sometimes referred to as "diamine (1)") is an aromatic diamine having one to three benzene rings. Diamine (1) has a rigid structure, which has the effect of imparting an ordered structure to the entire polymer. This results in a polyimide with low gas permeability and low moisture absorption, and the moisture content inside the molecular chain can be reduced, thereby lowering the dielectric loss tangent. Here, a single bond is preferred as the linking group Z.

[0066] Examples of diamine (1) include 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-n-propyl-4,4'-diaminobiphenyl (m-NPB), and 4-aminophenyl-4'-aminobenzoate (APAB).

[0067] Thermoplastic polyimide layer: The thermoplastic polyimide contains a tetracarboxylic acid residue and a diamine residue, and preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic acid dianhydride and an aromatic diamine residue derived from an aromatic diamine.

[0068] (tetracarboxylic acid residue) As the tetracarboxylic acid residue used in the thermoplastic polyimide, the same tetracarboxylic acid residues as those exemplified above for the non-thermoplastic polyimide can be used.

[0069] (diamine residue) The diamine residue contained in the thermoplastic polyimide is preferably a diamine residue derived from a diamine compound represented by any of the general formulae (B1) to (B7).

[0070] [ka]

[0071] In formulas (B1) to (B7), R1 independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, linking groups A independently represent a divalent group selected from -O-, -S-, -CO-, -SO-, -SO2-, -COO-, -CH2-, -C(CH3)2-, -NH-, or -CONH-, and n1 independently represents an integer of 0 to 4. However, formula (B3) excluding those that overlap with formula (B2), and formula (B5) excluding those that overlap with formula (B4). Here, "independently" means that in one or more of formulas (B1) to (B7), multiple linking groups A, multiple R1s, or multiple n1s may be the same or different. In the above formulas (B1) to (B7), the hydrogen atoms in the two terminal amino groups may be substituted, for example, -NR2R3 (where R2 and R3 independently represent any substituent such as an alkyl group).

[0072] The diamine represented by formula (B1) (hereinafter sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. In this diamine (B1), the amino group directly bonded to at least one benzene ring and the divalent linking group A are located at the meta position, which increases the degree of freedom of the polyimide molecular chain and provides high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B1) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH2-, -C(CH3)2-, -CO-, -SO2-, or -S-.

[0073] Examples of the diamine (B1) include 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, and (3,3'-bisamino)diphenylamine.

[0074] The diamine represented by formula (B2) (hereinafter sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. In this diamine (B2), the amino group directly bonded to at least one benzene ring and the divalent linking group A are located at the meta position, which increases the degree of freedom of the polyimide molecular chain and provides high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B2) enhances the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

[0075] Examples of the diamine (B2) include 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzenamine, and 3-[3-(4-aminophenoxy)phenoxy]benzenamine.

[0076] The diamine represented by formula (B3) (hereinafter sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. This diamine (B3) has two divalent linking groups A directly bonded to one benzene ring, which are mutually meta-positioned. This increases the degree of freedom of the polyimide molecular chain, resulting in high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B3) enhances the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

[0077] Examples of diamine (B3) include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, and 4,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline.

[0078] The diamine represented by formula (B4) (hereinafter sometimes referred to as "diamine (B4)") is an aromatic diamine having four benzene rings. This diamine (B4) has high flexibility due to the presence of an amino group directly bonded to at least one benzene ring and a divalent linking group A at the meta position, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B4) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH2-, -C(CH3)2-, -SO2-, -CO-, or -CONH-.

[0079] Examples of the diamine (B4) include bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, and bis[4,4'-(3-aminophenoxy)]benzanilide.

[0080] The diamine represented by formula (B5) (hereinafter sometimes referred to as "diamine (B5)") is an aromatic diamine having four benzene rings. In this diamine (B5), two divalent linking groups A directly bonded to at least one benzene ring are located at meta positions relative to each other, which increases the degree of freedom of the polyimide molecular chain and provides high flexibility, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B5) enhances the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

[0081] Examples of the diamine (B5) include 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, and the like.

[0082] The diamine represented by formula (B6) (hereinafter sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. This diamine (B6) has high flexibility due to the presence of at least two ether bonds, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B6) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -C(CH3)2-, -O-, -SO2-, or -CO-.

[0083] Examples of diamine (B6) include 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), and bis[4-(4-aminophenoxy)phenyl]ketone (BAPK).

[0084] The diamine represented by formula (B7) (hereinafter sometimes referred to as "diamine (B7)") is an aromatic diamine having four benzene rings. This diamine (B7) has a highly flexible divalent linking group A on both sides of the diphenyl skeleton, which is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B7) enhances the thermoplasticity of the polyimide. Here, -O- is preferred as the linking group A.

[0085] Examples of the diamine (B7) include bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl, and the like.

[0086] The thermoplastic polyimide preferably contains 60 mol % or more, preferably 60 mol % to 99 mol %, and more preferably 70 mol % to 95 mol % of diamine residues derived from at least one diamine compound selected from diamines (B1) to (B7) relative to the total diamine residues. Because diamines (B1) to (B7) have flexible molecular structures, using at least one diamine compound selected from these compounds in an amount within the above range improves the flexibility of the polyimide molecular chain and imparts thermoplasticity. If the total amount of diamines (B1) to (B7) in the raw materials is less than 60 mol % relative to the total diamine components, the polyimide will lack flexibility and will not exhibit sufficient thermoplasticity.

[0087] Furthermore, diamine residues derived from diamine compounds represented by general formula (1) are also preferred as diamine residues contained in thermoplastic polyimides. The diamine compounds represented by general formula (1) [diamine (1)] are as described in the description of non-thermoplastic polyimides. Diamine (1) has a rigid structure and acts to impart an ordered structure to the entire polymer, thereby suppressing molecular motion and reducing the dielectric loss tangent and moisture absorption. Furthermore, when used as a raw material for thermoplastic polyimides, polyimides with low gas permeability and excellent long-term heat-resistant adhesiveness can be obtained.

[0088] The thermoplastic polyimide may contain diamine residues derived from diamine (1) in an amount of preferably 1 mol % to 40 mol %, more preferably 5 mol % to 30 mol %, based on the total diamine residues. By using diamine (1) in an amount within the above range, an ordered structure is formed throughout the polymer due to the rigid structure derived from the monomer, resulting in a polyimide that is thermoplastic yet has low gas permeability and moisture absorption and excellent long-term heat-resistant adhesiveness.

[0089] The thermoplastic polyimide constituting the thermoplastic polyimide layer may contain diamine residues derived from diamine compounds other than diamines (1) and (B1) to (B7) within the scope of the invention.

[0090] In the thermoplastic polyimide, the thermal expansion coefficient, tensile modulus, glass transition temperature, etc. can be controlled by selecting the types of the tetracarboxylic acid residue and diamine residue, or by selecting the molar ratio of each when two or more types of tetracarboxylic acid residues or diamine residues are used. Furthermore, when the thermoplastic polyimide has a plurality of polyimide structural units, they may be present as blocks or randomly, but are preferably present randomly.

[0091] <Number of polar groups in the insulating resin layer in contact with adhesive layer B> Polyimide is suitable for the insulating resin layers R1 and R2, but to reduce dielectric loss, it is preferable to have as few polar groups as possible in the polyimide molecular chain. The present invention is effective in improving adhesion to such polyimides with few polar groups and excellent dielectric properties. Specifically, for the insulating resin layers R1 and R2 in contact with the adhesive layer B, polyimides with fewer than eight polar groups per repeating unit of the acid anhydride residue and diamine residue of the polyimide are suitable. Here, "per repeating unit of the acid anhydride residue and diamine residue" means that one unit is an acid anhydride residue and a diamine residue linked by an imide bond in the polyimide chain, and the combination of the types of acid anhydride residue and diamine residue is not important. The number of polar groups can be calculated using the following formula (2):

[0092] Number of polar groups = (Number of polar groups in diamine residue) × (molar ratio of diamine residue) + (Number of polar groups in acid anhydride residue) × (molar ratio of acid anhydride residue) + (Number of imide groups) × 3 (2) [Here, the sum of the molar ratios of diamine residues + the sum of the molar ratios of acid anhydride residues is assumed to be 2, and the number of polar groups is calculated as one each of -X (where X is a halogen atom), -OH, -SH, -O-, -S-, -SO-, -NH-, -CO-, -CN, -P=O, and -PO-, two each of -SO2- and -CONH-, and three each of -S03H and -(CO)2N- (imido group).]

[0093] <Adhesive layer> The adhesive layer B is composed of a thermoplastic resin or a thermosetting resin that has the property of being cured by heat. Here, in the case of a thermoplastic resin, curing also includes, for example, forming crosslinks by heat. Preferred thermoplastic resins or thermosetting resins include, for example, polyimide resins, polyamide resins, epoxy resins, phenoxy resins, acrylic resins, polyurethane resins, styrene resins, polyester resins, phenolic resins, polysulfone resins, polyethersulfone resins, polyphenylene sulfide resins, polyethylene resins, polypropylene resins, silicone resins, polyetherketone resins, polyvinyl alcohol resins, polyvinyl butyral resins, styrene-maleimide copolymers, maleimide-vinyl compound copolymers, or (meth)acrylic copolymers, benzoxazine resins, bismaleimide resins, and cyanate ester resins.

[0094] When adhesive layer B is a thermosetting resin, it may contain an organic peroxide, a curing agent, a curing accelerator, etc., and if necessary, a curing agent and a curing accelerator, or a catalyst and a co-catalyst may be used in combination.

[0095] An aliphatic polyimide using an aliphatic diamine as a raw material can be cited as an example of the resin constituting the adhesive layer B. The aliphatic polyimide is a thermoplastic polyimide obtained by reacting an acid dianhydride component with a diamine component containing an aliphatic diamine. As the acid dianhydride component serving as the raw material for aliphatic polyimides, monomers generally used in the synthesis of thermoplastic polyimides can be used, such as 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), p-phenylenebis(trimellitic acid monoester anhydride) (TAHQ), and ethylene glycol. Aromatic acid dianhydrides such as bisanhydrotrimellitate (TMEG), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and 2,3',3,4'-biphenyltetracarboxylic dianhydride are preferred, with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) being more preferred. The aliphatic polyimide preferably contains 40 to 100 mol %, and more preferably 60 to 100 mol %, of acid dianhydride residues derived from one or more of the above aromatic acid dianhydrides relative to the total acid dianhydride residues.

[0096] As the diamine component serving as the raw material for the aliphatic polyimide, a monomer generally used in the synthesis of thermoplastic polyimides can be used, but from the viewpoint of lowering the dielectric dissipation factor and improving the dielectric properties, it is preferable to use a dimer diamine composition. That is, the aliphatic polyimide preferably contains 20 mol % or more, more preferably 50 mol % or more, and most preferably 70 to 100 mol % of diamine residues derived from the dimer diamine composition relative to the total diamine residues. By containing the diamine residues derived from the dimer diamine composition in the above amount, the glass transition temperature Tg BThis can improve thermocompression bonding properties by lowering the temperature (lowering Tg), and further alleviate internal stress by lowering the elastic modulus, while improving the dielectric properties of adhesive layer B. If the content of diamine residues derived from the dimer diamine composition is less than 20 mol % with respect to all diamine residues, transmission loss during high-frequency transmission may increase, or sufficient adhesion to insulating resin layer R1 may not be obtained.

[0097] The dimer diamine composition is a mixture containing the following component (a) as a main component and optionally containing components (b) and (c), and is a purified product in which the amounts of components (b) and (c) are controlled. (a) Dimer diamine (b) Monoamine compounds obtained by substituting the terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group. (c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the dimer diamine).

[0098] The dimer diamine of component (a) refers to a diamine in which the two terminal carboxylic acid groups (—COOH) of a dimer acid are replaced with primary aminomethyl groups (—CH—NH) or amino groups (—NH). Dimer acids are known dibasic acids obtained by the intermolecular polymerization of unsaturated fatty acids. Their industrial production process is largely standardized in the industry, and they are obtained by dimerizing unsaturated fatty acids with 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acids are primarily composed of a 36-carbon dibasic acid obtained by dimerizing 18-carbon unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. However, depending on the degree of purification, they may contain arbitrary amounts of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids with 20 to 54 carbon atoms. Although double bonds remain after the dimerization reaction, in the present invention, dimer acids that have been further hydrogenated to reduce the degree of unsaturation are also included in the definition of dimer acids. The dimer diamine of component (a) can be defined as a diamine compound obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0099] Dimer diamine is characterized by its ability to impart properties derived from the dimer acid skeleton. Specifically, because dimer diamine is a macromolecular aliphatic molecule with a molecular weight of approximately 560 to 620, it can increase the molecular molar volume and relatively reduce the polar groups in polyimides. These characteristics of dimer diamine are believed to contribute to improving the dielectric properties of polyimides by reducing their relative dielectric constant and dielectric dissipation factor while suppressing a decrease in their heat resistance. Furthermore, because dimer diamine contains two freely movable hydrophobic chains with 7 to 9 carbon atoms and two linear aliphatic amino groups with a length approaching 18 carbon atoms, it not only imparts flexibility to polyimides but also allows them to have asymmetric or nonplanar chemical structures, thereby potentially lowering the dielectric constant of polyimides.

[0100] The dimer diamine composition used should be one in which the dimer diamine content of component (a) has been increased to 96% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more, by a purification method such as molecular distillation. By increasing the dimer diamine content of component (a) to 96% by weight or more, the broadening of the molecular weight distribution of the polyimide can be suppressed. If technically possible, it is best for the entire dimer diamine composition (100% by weight) to be composed of component (a) dimer diamine. In addition, the dimer diamine composition preferably has a total area percentage of components (b) and (c) of 4% or less, preferably less than 4%, in a chromatogram obtained by GPC measurement. The area percentage of the chromatogram of component (b) is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less, and the area percentage of the chromatogram of component (c) is preferably 2% or less, more preferably 1.8% or less, and even more preferably 1.5% or less. By achieving these ranges, a rapid increase in the molecular weight of the polyimide can be suppressed, and an increase in the dielectric loss tangent of the resin film over a wide frequency range can be suppressed. Note that components (b) and (c) do not necessarily need to be present in the dimer diamine composition.

[0101] Commercially available dimer diamine compositions are available, such as PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan. When using these commercially available products, they are preferably purified to reduce the amount of components other than dimer diamine, and for example, it is preferable to make the dimer diamine content 96% by weight or more. The purification method is not particularly limited, but known methods such as distillation and precipitation purification are suitable.

[0102] Aliphatic polyimides can be made using diamine compounds other than the dimer diamine composition as raw materials, as long as the effects of the present invention are not impaired. Examples of preferred diamine compounds that can be used for aliphatic polyimides include the diamine compounds represented by the general formulas (B1) to (B7). Among the diamine compounds represented by the general formulas (B1) to (B7), it is preferable to use, for example, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)benzene (APB), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS).

[0103] In order to increase the flexibility of adhesive layer B and reduce residual stress after thermocompression bonding due to the low elastic modulus of the aliphatic polyimide, the content of diamine residues derived from diamine compounds represented by general formulas (B1) to (B7) is preferably within the range of 5 to 50 mol %, more preferably within the range of 10 to 30 mol %, relative to all diamine residues.

[0104] In aliphatic polyimides, the thermal expansion coefficient, glass transition temperature, dielectric properties, etc. can be controlled by selecting the types of acid dianhydride components and diamine components, or by selecting the respective molar ratios when two or more types of acid dianhydrides or diamines are used.

[0105] The weight-average molecular weight of the aliphatic polyimide is, for example, preferably in the range of 10,000 to 400,000, more preferably in the range of 20,000 to 350,000. If the weight-average molecular weight is less than 10,000, the strength of the adhesive layer B tends to decrease and the adhesive layer B tends to become brittle. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity increases excessively, and the adhesive layer B tends to have defects such as uneven thickness and streaks during the coating process.

[0106] The aliphatic polyimide is most preferably a completely imidized structure. However, a portion of the polyimide may be an amic acid. The imidization rate can be determined by measuring the infrared absorption spectrum of a polyimide thin film by a single-reflection ATR method using a Fourier transform infrared spectrophotometer (commercially available: FT / IR620 manufactured by JASCO Corporation) at 1015 cm -1 Based on the benzene ring absorber near 1780cm -1 It can be calculated from the absorbance of the C=O stretching derived from the imide group.

[0107] The glass transition temperature (Tg) of the aliphatic polyimide is preferably 250° C. or lower, and more preferably within the range of 40° C. to 200° C. When the Tg of the aliphatic polyimide is 250° C. or lower, thermocompression bonding can be performed at low temperatures, which alleviates internal stress generated during lamination and suppresses dimensional changes after circuit processing.

[0108] When an aliphatic polyimide has a ketone group, the ketone group can be reacted with the amino group of an amino compound having at least two primary amino groups as functional groups to form a crosslinked structure via a C=N bond through thermal condensation, thereby curing the polyimide. The formation of a crosslinked structure can improve the heat resistance of the aliphatic polyimide. Examples of suitable tetracarboxylic acid anhydrides for forming aliphatic polyimides having ketone groups include 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), and examples of suitable diamine compounds include aromatic diamines such as 4,4'-bis(3-aminophenoxy)benzophenone (BABP) and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB).

[0109] Examples of amino compounds that can be used to crosslink aliphatic polyimides include dihydrazide compounds, aromatic diamines, and aliphatic amines. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form crosslinked structures even at room temperature, raising concerns about the storage stability of the varnish. On the other hand, aromatic diamines require high temperatures to form crosslinked structures. When a dihydrazide compound is used, it is possible to achieve both the storage stability of the varnish and a shortened curing time. Examples of dihydrazide compounds include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, and diglycerides. Preferred dihydrazide compounds include cholic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4-bisbenzenedihydrazide, 1,4-naphthoic acid dihydrazide, 2,6-pyridine dioic acid dihydrazide, itaconic acid dihydrazide, etc. The above dihydrazide compounds may be used alone or in combination of two or more.

[0110] When crosslinking an aliphatic polyimide, the amino compound is added to a resin solution containing an aliphatic polyimide having a ketone group, and the ketone group in the aliphatic polyimide and the primary amino group of the amino compound undergo a condensation reaction. This condensation reaction hardens the resin solution to form a cured product. In this case, the amino compound can be added in such an amount that the total number of primary amino groups per mole of ketone group is 0.004 to 1.5 moles, preferably 0.005 to 1.2 moles, more preferably 0.03 to 0.9 moles, and most preferably 0.04 to 0.5 moles. If the amount of amino compound added is such that the total number of primary amino groups per mole of ketone group is less than 0.004 moles, the crosslinking of the aliphatic polyimide by the amino compound is insufficient, and the adhesive layer B after curing tends to have difficulty exhibiting heat resistance. If the amount of amino compound added is such that the total number of primary amino groups per mole of ketone group is more than 1.5 moles, the unreacted amino compound tends to act as a thermoplasticizer, reducing the heat resistance of the adhesive layer B.

[0111] The conditions for the condensation reaction for crosslink formation are not particularly limited, as long as they are conditions under which the ketone group in the aliphatic polyimide reacts with the primary amino group of the amino compound to form an imine bond (C=N bond). The temperature of the thermal condensation is preferably within the range of, for example, 120 to 220°C, more preferably 140 to 200°C, for reasons such as releasing water produced by condensation out of the system or simplifying the condensation step when the thermal condensation reaction is carried out subsequently to the synthesis of the aliphatic polyimide. The reaction temperature and reaction time may be set so that the value X or the total value X1 is 8000 or more in the heat treatment step. The end point of the reaction can be determined by measuring the infrared absorption spectrum using, for example, a Fourier transform infrared spectrophotometer (commercially available: FT / IR620 manufactured by JASCO Corporation) at 1670 cm -1 The decrease or disappearance of the absorption peak due to the ketone group in the polyimide resin near 1635 cm -1 This can be confirmed by the appearance of an absorption peak derived from a nearby imine group.

[0112] The thermal condensation of the ketone group of the aliphatic polyimide with the primary amino group of the amino compound can be carried out, for example, by processing the aliphatic polyimide composition to which the amino compound has been added into a predetermined shape (for example, after applying it to any substrate or forming it into a film), followed by heating.

[0113] The formation of imine bonds has been described as a method for forming a crosslinked structure to impart heat resistance to an aliphatic polyimide. However, the present invention is not limited to this method. For example, an aliphatic polyimide can be cured by blending an epoxy resin, an epoxy resin curing agent, or the like.

[0114] By using the above aliphatic polyimide, the adhesive layer B has excellent flexibility and dielectric properties (low dielectric constant and low dielectric loss tangent).

[0115] (CTE of adhesive layer) The thermoplastic or thermosetting resin constituting adhesive layer B has high thermal expansion but low elasticity and a low glass transition temperature, so that even if the CTE exceeds 30 ppm / K, it can alleviate the internal stress generated during lamination. Therefore, the CTE of adhesive layer B is preferably 35 ppm / K or more, more preferably in the range of 35 ppm / K to 200 ppm / K, and even more preferably in the range of 35 ppm / K to 150 ppm / K. By appropriately changing the combination of raw materials used, the thickness, and the drying and curing conditions, adhesive layer B can be made to have the desired CTE.

[0116] (Dielectric loss tangent of adhesive layer) When adhesive layer B is applied to, for example, a circuit board, in order to suppress deterioration of dielectric loss, the dielectric loss tangent (Tan δ) at 10 GHz is preferably 0.004 or less, more preferably 0.003 or less, and even more preferably 0.002 or less. If the dielectric loss tangent at 10 GHz of adhesive layer B exceeds 0.004, when applied to a circuit board, problems such as loss of electrical signals are likely to occur in the transmission path of high-frequency signals. On the other hand, there is no particular lower limit for the dielectric loss tangent at 10 GHz of adhesive layer B.

[0117] (relative dielectric constant of adhesive layer) In order to ensure impedance matching when applied to, for example, a circuit board, adhesive layer B preferably has a relative dielectric constant (ε) of 4.0 or less at 10 GHz. If the relative dielectric constant of adhesive layer B at 10 GHz exceeds 4.0, when applied to a circuit board, this leads to an increase in the dielectric loss of adhesive layer B, which is likely to cause problems such as loss of electrical signals on the transmission path of high-frequency signals.

[0118] (filler) The adhesive layer B may contain a filler as needed. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, and metal salts of organic phosphinic acid. These may be used alone or in combination of two or more.

[0119] <Layer thickness> Metal clad laminate C A ,C B In the above, the thickness TT1 of the adhesive layer B is preferably in the range of 50 to 450 μm, and more preferably in the range of 50 to 250 μm. If the thickness TT1 of the adhesive layer B is less than the above lower limit, the transmission loss as a high-frequency substrate may increase. On the other hand, if the thickness of the adhesive layer B exceeds the above upper limit, problems such as reduced dimensional stability may occur.

[0120] Metal clad laminate C A ,C B In the above, the thickness TT2 of the insulating resin layer R1 and the insulating resin layer R2 is preferably in the range of 12 to 100 μm, and more preferably in the range of 12 to 50 μm. If the thickness TT2 of the insulating resin layer R1 and the insulating resin layer R2 is less than the above lower limit, the metal-clad laminate C A ,C B If the thickness TT2 of the insulating resin layer R1 and the insulating resin layer R2 exceeds the upper limit, problems such as reduced productivity may occur. Note that the insulating resin layer R1 and the insulating resin layer R2 do not necessarily have to have the same thickness.

[0121] Metal clad laminate C B In this case, the total thickness TT3 of the insulating resin layer R1, adhesive layer B, and insulating resin layer R2 is preferably within a range of 70 to 500 μm, and more preferably within a range of 100 to 300 μm. If the total thickness TT3 is less than 70 μm, the effect of reducing transmission loss when made into a circuit board will be insufficient, and if it exceeds 500 μm, there is a risk of a decrease in productivity. The ratio (TT1 / TT3) of the thickness TT1 of the adhesive layer B to the total thickness TT3 is preferably in the range of 0.5 to 0.8, more preferably 0.5 to 0.7. If the ratio (TT1 / TT3) is less than 0.5, it becomes difficult to make TT3 70 μm or more, and if it exceeds 0.8, problems such as reduced dimensional stability occur.

[0122] <Adhesion between insulating resin layer and adhesive layer> Metal clad laminate C A ,C BIn this case, the interlayer adhesion between at least the insulating resin layer R1 and the adhesive layer B, i.e., the peel strength, is preferably 0.7 kN / m or more, and more preferably 1.0 kN / m or more. Peel strength can be measured using the method and conditions described in the Examples below. If the peel strength is less than 0.7 kN / m, delamination is likely to occur during circuit processing such as drilling and cutting, leading to deterioration in the processing yield and reliability of the circuit board. The reason why the interlayer adhesion between the insulating resin layer R1 and the adhesive layer B is emphasized here is that the boundary between these layers is an interface formed by lamination, and therefore peel strength is less likely to be exhibited than at a cast-side interface formed by applying a resin composition solution (for example, the interface between the insulating resin layer R1 and the adhesive layer B in the third embodiment). In the third embodiment, the peel strength is preferably 0.7 kN / m or more, and more preferably 1.0 kN / m or more, not only between the insulating resin layer R1 and the adhesive layer B but also between the insulating resin layer R2 and the adhesive layer B. Also, as in the second embodiment, when both the interface between the insulating resin layer R1 and the adhesive layer B and the interface between the insulating resin layer R2 and the adhesive layer B are formed by bonding, the peel strength between each of the layers is preferably 0.7 kN / m or more, and more preferably 1.0 kN / m or more.

[0123] [Circuit board] The metal-clad laminate C of this embodiment obtained as described above A ,C B By subjecting the metal layer M1 and / or the metal layer M2 to wiring circuit processing, for example, by etching, a circuit board such as a single-sided FPC or a double-sided FPC can be manufactured. [Example]

[0124] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, various measurements and evaluations were carried out according to the following methods unless otherwise specified.

[0125] [Viscosity measurement] The viscosity of the resin was measured at 25°C using an E-type viscometer (Brookfield, product name: DV-II+Pro). The rotation speed was set so that the torque was 10% to 90%, and the viscosity was read when the viscosity stabilized 2 minutes after the start of measurement.

[0126] [Measurement of glass transition temperature (Tg) and adhesive temperature] The glass transition temperature was measured using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, product name: E4000F) by stepwise heating a 5mm x 20mm cured film from 30°C to 400°C at a heating rate of 4°C / min and a frequency of 11Hz. The temperature at which Tanδ reached a maximum during the measurement was defined as Tg. The adhesion temperature was defined as the temperature above the glass transition temperature on the loss modulus-temperature curve, which is 22% higher than the temperature at which the tangent to the curve first becomes -7kPa / °C.

[0127] [Peel strength measurement] The metal-clad laminate with the adhesive layer was cut into 0.5 mm wide pieces and fixed to an aluminum plate with double-sided tape. The adhesive layer and the insulating resin layer were peeled off using a Tensilon tester (manufactured by Toyo Seiki Seisakusho, product name: Strograph VE-1D) to measure the peel strength. The single-sided metal-clad laminate was pulled in a 180° direction at a rate of 50 mm / min, and the median strength was determined when it had peeled 10 mm.

[0128] [Measurement of adhesive layer curing temperature] The curing temperature of the adhesive layer was measured using a rheometer (Anton Paar, product name: MCR302) at a heating rate of 5°C / min and an angular frequency of 6.28 rad / s. The curing temperature of the adhesive layer was defined as the temperature 25% higher than the temperature at which the complex viscosity was minimized.

[0129] [Measurement of tensile modulus] The tensile modulus of the adhesive layer was measured using a Strograph R-1 manufactured by Toyo Seiki Seisakusho, under the following conditions in an environment of a temperature of 23°C and a relative humidity of 50%. Test piece size: length 160mm x width 12.7mm Grip distance: 101.6 mm Tensile speed: 50 mm / min

[0130] [Measurement of weight average molecular weight (Mw)] The weight-average molecular weight was measured by gel permeation chromatography (manufactured by Tosoh Corporation, trade name: HLC-8220GPC). Polystyrene was used as a standard substance, and THF was used as a developing solvent.

[0131] The abbreviations used in the examples and comparative examples represent the following compounds. BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PMDA: Pyromellitic dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis(4-aminophenoxy)benzene Bisaniline-M: 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene NMP: N-methyl-2-pyrrolidone DMAc: N,N-dimethylacetamide BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride DDA: aliphatic diamine having 36 carbon atoms (manufactured by Croda Japan Co., Ltd., trade name: PRIAMINE 1074, amine value: 205 mg KOH / g, mixture of dimer diamines with cyclic and chain structures, dimer content: 95% by weight or more) N-12: Dodecanedioic acid dihydrazide OP935: organic phosphinic acid aluminum salt (manufactured by Clariant Japan, trade name: Exolit OP935)

[0132] (Synthesis Example 1) <Preparation of resin solution for adhesive layer> A 500 mL four-neck flask equipped with a nitrogen inlet tube, stirrer, thermocouple, Dean-Stark trap, and condenser was charged with 44.92 g of BTDA (0.139 mol), 75.08 g of DDA (0.141 mol), 168 g of NMP, and 112 g of xylene, and mixed at 40°C for 30 minutes to prepare a polyamic acid solution. The polyamic acid solution was heated to 190°C and stirred for 4 hours, after which the distilled water and xylene were removed from the system. The solution was then cooled to 100°C, 112 g of xylene was added, stirred, and further cooled to 30°C to prepare polyimide solution 1 (solids content: 29.5 wt%, weight average molecular weight: 75,700), in which imidization was completed.

[0133] Polyimide varnish 1 was prepared by blending 1.8 g of N-12 (0.0036 mol) and 12.5 g of OP935 with 169.49 g of polyimide solution 1 (50 g as solid content), and diluting with the addition of 6.485 g of NMP and 19.345 g of xylene.

[0134] (Synthesis Example 2) <Preparation of polyamic acid solution for insulating resin layer> 69.56 g of m-TB (0.328 mol), 542.75 g of TPE-R (1.857 mol), DMAc in an amount to give a solids concentration of 12 wt% after polymerization, 194.39 g of PMDA (0.891 mol), and 393.31 g of BPDA (1.337 mol) were added, and the mixture was stirred at room temperature for 3 hours to polymerize the mixture, yielding polyamic acid solution 1 (viscosity: 2,650 cps). The number of polar groups per repeating unit of the acid anhydride and diamine residues in the insulating resin layer fabricated using polyamic acid solution 1 was 7.7.

[0135] (Synthesis Example 3) <Preparation of polyamic acid solution for insulating resin layer> Under a nitrogen stream, 64.20 g of m-TB (0.302 mol), 5.48 g of bisaniline-M (0.016 mol), and an amount of DMAc sufficient to achieve a solids concentration of 15 wt% after polymerization were added to a reaction vessel and stirred at room temperature. Next, 34.20 g of PMDA (0.157 mol) and 46.13 g of BPDA (0.157 mol) were added, followed by stirring at room temperature for 3 hours to allow the polymerization reaction to proceed, yielding polyamic acid solution 2 (viscosity: 26,500 cps). The number of polar groups per repeating unit of the acid anhydride and diamine residues in the insulating resin layer fabricated using polyamic acid solution 2 was 6.0.

[0136] (Production Example 1) <Preparation of adhesive sheet for adhesive layer> Polyimide varnish 1 was applied to the silicone-treated surface of a release substrate (length x width x thickness = 320 mm x 240 mm x 25 μm) so that the thickness after drying was 60 μm, and then the coating was dried by heating at 80°C for 15 minutes and peeled off from the release substrate to prepare adhesive sheet 1. When the curing temperature of adhesive sheet 1 was measured using a rheometer, the curing temperature was 160°C and the tensile modulus was 0.4 GPa. When the adhesive temperature of adhesive sheet 1 after curing was evaluated, it was 158°C and the tensile modulus was 0.8 GPa.

[0137] (Production Example 2) <Preparation of single-sided metal-clad laminate 1> Polyamic acid solution 2 was uniformly applied onto electrolytic copper foil (thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) to a thickness of approximately 2 to 3 μm after curing, and then heated and dried at 120°C to remove the solvent. Next, polyamic acid solution 1 was uniformly applied onto the above to a thickness of approximately 16 μm after curing, and then heated and dried at 120°C to remove the solvent. Polyamic acid solution 2 was further uniformly applied onto the above to a thickness of approximately 2 to 3 μm after curing, and then heated and dried at 120°C to remove the solvent. Further, stepwise heat treatment was performed from 120°C to 360°C to complete the imidization, forming a polyimide layer as an insulating resin layer, and single-sided metal-clad laminate 1 was prepared.

[0138] <Preparation of Polyimide Film> Polyamic acid solution 1 was uniformly applied to an electrolytic copper foil (thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) to a thickness of approximately 10 μm after curing. The coating was then heated and dried at 120°C to remove the solvent, and the coating was then subjected to a stepwise heat treatment from 120°C to 360°C to complete the imidization. The copper foil layer was then etched away using an aqueous ferric chloride solution, and the Tg of the resulting polyimide film was evaluated to be 220°C. The Tg of a polyimide film prepared from polyamic acid solution 2 was also evaluated in the same manner as above, and was found to be 310°C.

[0139] (Production Example 3) <Preparation of single-sided metal-clad laminate 2> Polyamic acid solution 2 was uniformly applied onto electrolytic copper foil (thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) so that the thickness after curing would be approximately 2 to 3 μm, and then heated and dried at 120°C to remove the solvent. Next, polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing would be approximately 18 μm, and then heated and dried at 120°C to remove the solvent. Further, stepwise heat treatment was performed from 120°C to 360°C to complete imidization, form an insulating resin layer, and prepare a single-sided metal-clad laminate 2.

[0140] Example 1 <Preparation of double-sided metal-clad laminate> A double-sided metal-clad laminate copper foil was prepared using a roll-to-roll process as follows. Polyimide varnish 1 was uniformly applied to the polyimide layer of single-sided metal-clad laminate 1 to a dry thickness of 60 μm. The polyimide varnish was then dried at 150°C to remove the solvent, forming adhesive layer 1. The adhesive layer 1 was then temporarily bonded to the polyimide layer side of another single-sided metal-clad laminate 1 at 80°C, producing double-sided metal-clad laminate intermediate 1. The rolled double-sided metal-clad laminate intermediate 1 was then heat-treated in a thermostatic oven at 160°C for 48 hours to obtain double-sided metal-clad laminate 1. The peel strength between the temporarily bonded single-sided metal-clad laminate 1 and adhesive layer 1 was evaluated and found to be 0.87 kN / m.

[0141] Examples 2 to 6 The peel strength between the single-sided metal-clad laminate 1 and the adhesive layer 1 on the pre-press bonded side was evaluated in the same manner as in Example 1, except that the temperature of the thermostatic bath and the heat treatment time were changed as shown in Table 1.

[0142] (Examples 7 to 8) The peel strength between the single-sided metal-clad laminate 1 and the adhesive layer 1 on the pre-press bonded side was evaluated in the same manner as in Example 1, except that the temperature of the thermostatic bath and the heating treatment time were changed in stages as shown in Table 1.

[0143] Examples 9 to 11 The peel strength between the single-sided metal-clad laminate 2 and the adhesive layer 1 on the pre-pressed side was evaluated in the same manner as in Example 1, except that single-sided metal-clad laminate 2 was used instead of single-sided metal-clad laminate 1 and the temperature of the thermostatic oven and the heating treatment time were changed as shown in Table 1.

[0144] (Comparative Examples 1 and 2) The peel strength between the single-sided metal-clad laminate 1 and the adhesive layer 1 on the pre-press bonded side was evaluated in the same manner as in Example 1, except that the temperature of the thermostatic bath and the heat treatment time were changed as shown in Table 1.

[0145] [Table 1]

[0146] Example 12 <Preparation of double-sided metal-clad laminate> Two single-sided metal-clad laminates 1 were prepared, and the polyimide layer side of each was overlapped on both sides of adhesive sheet 1, and they were pressed together at 180°C for 4 hours under a pressure of 3.5 MPa to prepare a double-sided metal-clad laminate. The peel strength between the insulating resin layer of single-sided metal-clad laminate 1 and adhesive sheet 1 was evaluated and found to be 0.82 kN / m.

[0147] (Comparative Example 3) <Preparation of double-sided metal-clad laminate> Two single-sided metal-clad laminates 1 were prepared, and the insulating resin layer side of each was overlapped on both sides of adhesive sheet 1, and they were pressed together at 180°C for 2 hours under a pressure of 3.5 MPa to prepare a double-sided metal-clad laminate. The peel strength between the insulating resin layer of single-sided metal-clad laminate 1 and adhesive sheet 1 was evaluated and found to be 0.65 kN / m.

[0148] Example 13 <Preparation of single-sided metal-clad laminate with adhesive layer> One single-sided metal-clad laminate 1 was prepared, adhesive sheet 1 was placed on the insulating resin layer side, and the laminate was pressed together at 180°C for 4 hours under a pressure of 3.5 MPa to prepare a single-sided metal-clad laminate with an adhesive layer. The peel strength between the insulating resin layer of single-sided metal-clad laminate 1 and adhesive sheet 1 was evaluated and found to be 0.84 kN / m.

[0149] Comparing Examples 1 to 11 with Comparative Examples 1 and 2, it can be seen that the comparative examples have a short heating time or a low heating temperature, so the total value X1 calculated by formula (1) is less than 50, and the peel strength is low. Furthermore, while Examples 7 and 8 undergo stepwise heat treatment, formula (1) can be applied, and it can be seen that sufficient peel strength is achieved when the total value X1 calculated by formula (1) is 50 or more. In Example 12, an adhesive sheet is used and pressure is applied to laminate the single-sided metal-clad laminate. However, as can be seen from Comparative Example 3, the peel strength of the insulating resin layer and adhesive layer is independent of pressure and depends on time, as in Examples 1 to 11, as long as the heat treatment temperature is above a predetermined level. Furthermore, the heat treatment conditions of the present invention can also be applied when preparing a single-sided metal-clad laminate with an adhesive layer, as in Example 13.

[0150] Although the embodiments of the present invention have been described in detail above for the purpose of illustration, the present invention is not limited to the above-described embodiments and various modifications are possible. [Explanation of symbols]

[0151] B...adhesive layer, BS...adhesive sheet, C A ,C B...metal-clad laminate, C1...first single-sided metal-clad laminate, C2...second single-sided metal-clad laminate, M1, M2...metal layers, R1, R2...insulating resin layers, S...intermediate laminate

Claims

1. A method for manufacturing a metal-clad laminate comprising: a first metal layer; a first insulating resin layer laminated on one surface of the first metal layer; and an adhesive layer laminated on the first insulating resin layer, a heat treatment step of heating the first insulating resin layer in a state where the adhesive sheet that will become the adhesive layer is in contact with the first insulating resin layer; The maximum temperature in the heat treatment step is in the range of the curing temperature of the adhesive layer or higher and the curing temperature + 50°C or lower, The difference (unit: ° C.) obtained by subtracting the adhesive temperature of the adhesive layer from the heat treatment temperature T at a certain point in the heat treatment process is defined as the total process time t Ａ A method for producing a metal-clad laminate, characterized in that the value integrated over [unit: h] is 50 [unit: °C h] or more (here, the adhesive temperature means a temperature that exceeds the glass transition temperature in the loss modulus-temperature curve obtained by measuring the dynamic viscoelasticity of the adhesive layer, and is a temperature that is 22% higher than the temperature at which the tangent slope of the curve first becomes -7 kPa / °C in the higher temperature range).

2. A method for manufacturing a metal-clad laminate comprising: a first metal layer; a first insulating resin layer laminated on one surface of the first metal layer; an adhesive layer laminated on the first insulating resin layer; a second insulating resin layer laminated on the adhesive layer; and a second metal layer laminated on the second insulating resin layer, a heat treatment step of heating an adhesive sheet to be the adhesive layer in contact with the first insulating resin layer or with both the first insulating resin layer and the second insulating resin layer, The maximum temperature in the heat treatment step is in the range of the curing temperature of the adhesive layer or higher and the curing temperature + 50°C or lower, The difference (unit: ° C.) obtained by subtracting the adhesive temperature of the adhesive layer from the heat treatment temperature T at a certain point in the heat treatment process is defined as the total process time t Ａ A method for producing a metal-clad laminate, characterized in that the value integrated over [unit: h] is 50 [unit: °C h] or more (here, the adhesive temperature means a temperature that exceeds the glass transition temperature in the loss modulus-temperature curve obtained by measuring the dynamic viscoelasticity of the adhesive layer, and is a temperature that is 22% higher than the temperature at which the tangent slope of the curve first becomes -7 kPa / °C in the higher temperature range).

3. A method for manufacturing a metal-clad laminate comprising: a first metal layer; a first insulating resin layer laminated on one surface of the first metal layer; an adhesive layer laminated on the first insulating resin layer; a second insulating resin layer laminated on the adhesive layer; and a second metal layer laminated on the second insulating resin layer, a coating film forming step of applying a solution of a resin composition that will become the adhesive layer to the second insulating resin layer and drying the applied film; a heat treatment step of heating the first insulating resin layer in a state where the first insulating resin layer is in contact with the coating film; The maximum temperature in the heat treatment step is in the range of the curing temperature of the adhesive layer or higher and the curing temperature + 50°C or lower, The difference (unit: ° C.) obtained by subtracting the adhesive temperature of the adhesive layer from the heat treatment temperature T at a certain point in the heat treatment process is defined as the total process time t Ａ A method for producing a metal-clad laminate, characterized in that the value integrated over [unit: h] is 50 [unit: °C h] or more (here, the adhesive temperature means a temperature that exceeds the glass transition temperature in the loss modulus-temperature curve obtained by measuring the dynamic viscoelasticity of the adhesive layer, and is a temperature that is 22% higher than the temperature at which the tangent slope of the curve first becomes -7 kPa / °C in the higher temperature range).

4. The method for manufacturing a metal-clad laminate according to any one of claims 1 to 3, wherein the heat treatment temperature in the heat treatment step is constant or changed stepwise multiple times, and the relationship between the heat treatment temperature and the heat treatment time satisfies the following mathematical formula (1). [Equation 1] [In formula (1), T １ｉ [unit: °C] is the difference obtained by subtracting the adhesive temperature of the adhesive layer from the i-th heat treatment temperature, and t i is the i-th heat treatment time (unit: h), and n is an integer of 1 or more.

5. The method for producing a metal-clad laminate according to any one of claims 1 to 4, wherein at least the heat treatment step is carried out in a rolled state.

6. The method for manufacturing a metal-clad laminate according to any one of claims 1 to 5, wherein a peel strength between the adhesive layer and the first insulating resin layer in the metal-clad laminate is 0.7 kN / m or more.

7. the adhesive layer comprises a polyimide containing an acid dianhydride residue derived from an acid dianhydride component and a diamine residue derived from a diamine component; The polyimide contains, relative to the total diamine residues, 7. A method for producing a metal-clad laminate according to claim 1, wherein the composition contains 20 mol% or more of a diamine residue derived from a dimer diamine composition mainly composed of a dimer diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

8. the first insulating resin layer contains a polyimide containing an acid dianhydride residue derived from an acid dianhydride component and a diamine residue derived from a diamine component; The method for producing a metal-clad laminate according to any one of claims 1 to 7, wherein the number of polar groups per repeating unit of the acid anhydride residue and the diamine residue contained in the first insulating resin layer is less than 8.

9. A method for manufacturing a circuit board, comprising a step of processing one or both of the first metal layer and the second metal layer in a metal-clad laminate manufactured by the method according to any one of claims 1 to 8 into wiring.

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