Metal-clad laminate, multilayer circuit board, electronic device, and electronic apparatus

Abstract

To provide a metal-clad laminate that can reduce adhesion and curling during a heating step.SOLUTION: A metal-clad laminate 100A includes a metal layer 110, a first insulating resin layer 40 laminated on one side of the metal layer 110, an adhesive layer AD laminated on the first insulating resin layer 40, and a second insulating resin layer 50A laminated on the adhesive layer AD. The second insulating resin layer 50A is different from the first insulating resin layer 40 in at least one of thickness, number of constituent layers, type of material, storage modulus, or coefficient of thermal expansion. The second insulating resin layer 50A exhibits a storage modulus of 1.0×109 Pa or more in a temperature range from 30°C to 200°C. A curl index, expressed by the absolute value (|MA-MB|) of the difference between the bending moment (MA) of the first insulating resin layer 40 and the bending moment (MB) of the second insulating resin layer 50A, is less than 10 mNm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a metal-clad laminate useful as an electronic component, a multilayer circuit board, and an electronic device and electronic equipment using the same. [Background technology]

[0002] As electronic devices become smaller, lighter, and more space-saving, there is an increasing demand for flexible printed circuit boards (FPCs), which are thin, lightweight, flexible, and have excellent durability even when bent repeatedly.FPCs allow for three-dimensional, high-density mounting even in limited spaces, and so their use in various electronic components is expanding.

[0003] In recent years, efforts have been made to increase transmission frequencies in order to transmit and process large volumes of information in the fields of information processing and communications, and there is a demand for circuit boards such as FPCs to reduce transmission loss by improving the dielectric properties of the insulating layer, and the same is true for metal-clad laminates, which are used as circuit board materials.

[0004] In order to accommodate the increasing frequency of transmission signals, metal-clad laminates and multilayer circuit boards having a laminated structure with an adhesive layer having a large thickness ratio have been proposed (for example, Patent Document 1 and Patent Document 2). Patent Document 1 discloses a metal-clad laminate having a laminated structure in which an adhesive layer having a low dielectric tangent and a large thickness ratio is interposed between the insulating resin layers of a pair of single-sided metal-clad laminates. Patent Document 2 discloses the use of a metal-clad laminate having a layer structure of metal layer / insulating resin layer / adhesive layer as a material for a multilayer circuit board. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-170417 [Patent Document 2] Japanese Patent Application Publication No. 2020-72198 Summary of the Invention [Problem to be solved by the invention]

[0006] When metal-clad laminates are processed into circuit boards such as FPCs, they must undergo numerous heating processes. For example, metal-clad laminates are typically stored in rolled form. To maintain consistent quality, they are sometimes subjected to heat drying in a rolled state at temperatures around 100°C. When metal-clad laminates have a layer structure consisting of a metal layer, an insulating resin layer, and an adhesive layer, the adhesive layer can soften and stick to the adjacent metal layer, resulting in adhesion. Furthermore, if the adhesive layer is thick, the process temperature, for example during the reflow process, can cause an imbalance in thermal stress in the insulating resin layer laminated adjacent to the adhesive layer, making them prone to curling. Such adhesion and curling not only reduce yield but also impair the reliability of electronic components, so countermeasures are needed.

[0007] An object of the present invention is to provide a metal-clad laminate that can suppress the occurrence of adhesion and curling during a heating process. [Means for solving the problem]

[0008] The inventors reviewed the laminated structure of the entire resin layer and discovered that the above problem could be solved by providing a new resin layer adjacent to the adhesive layer in a layer structure of metal layer / insulating resin layer / adhesive layer and controlling its physical properties, thereby completing the present invention.

[0009] That is, the metal-clad laminate of the present invention comprises a metal layer and a first insulating resin layer (A) consisting of a single layer or multiple layers laminated in contact with at least one surface of the metal layer; an adhesive layer laminated in contact with the first insulating resin layer (A); a second insulating resin layer (B) consisting of a single layer or multiple layers laminated in contact with the adhesive layer; The metal-clad laminate of the present invention comprises: The first insulating resin layer (A) and the second insulating resin layer (B) both satisfy the following conditions (I) to (III): (I) Storage modulus at 30°C is 1.0 x 10 9 Pa or greater; (II) The average thermal expansion coefficient from 250°C to 100°C is within the range of 10 to 30 ppm / K; (III) a glass transition temperature (Tg) of 180°C or higher; Furthermore, the metal-clad laminate of the present invention satisfies the following: the second insulating resin layer (B) is different from the first insulating resin layer (A) in at least one of thickness, number of constituent layers, material, storage modulus, and thermal expansion coefficient; The storage modulus of the second insulating resin layer (B) in the temperature range of 30°C to 200°C is 1.0 x 10 9 Pa or more, The bending moment (M A ) and the bending moment (M B ) absolute value of the difference (|M A -M B The curl index (|) is less than 10 mNm.

[0010] In the metal-clad laminate of the present invention, the exposed surface of the second insulating resin layer (B) has a storage modulus of 1.0 × 10 in a temperature range of 30°C to 200°C. 9 It may be more than Pa.

[0011] The metal-clad laminate of the present invention is prepared by subjecting the second insulating resin layer (B) to the following steps (1) to (3): (1) The second insulating resin layer (B) of the metal-clad laminate and another copper foil are thermocompression bonded under conditions of 150°C, 3.0 MPa, and 45 minutes; (2) After heat-pressing, cut it into a test piece 10 mm wide and 70 mm long; (3) The other copper foil is fixed, and the metal-clad laminate is pulled in a 180° direction at a speed of 50 mm / min, and the median strength when 10 mm of the second insulating resin layer (B) is peeled from the other copper foil is defined as the peel strength; The peel strength measured by may be less than 0.1 kN / m.

[0012] In the metal-clad laminate of the present invention, the ratio (t4 / t2) of the thickness t4 of the second insulating resin layer (B) to the thickness t2 of the first insulating resin layer (A) may be in the range of 0.5 to 2.0.

[0013] In the metal-clad laminate of the present invention, the adhesive layer satisfies the following conditions (i) to (iii): (i) The storage modulus at 50°C is 1800 MPa or less; (ii) the maximum storage modulus in the temperature range from 180°C to 260°C is 800 MPa or less; (iii) a glass transition temperature (Tg) of 180°C or less; The above condition may be satisfied.

[0014] In the metal-clad laminate of the present invention, the adhesive layer may contain an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue, The adhesive polyimide may contain 50 molar parts 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, per 100 molar parts of the diamine residues.

[0015] The multilayer circuit of the present invention comprises a first circuit board having a wiring layer formed on an insulating resin layer; a bonding sheet laminated in contact with the wiring layer of the first circuit board; a single-sided metal-clad laminate laminated in contact with the surface of the bonding sheet opposite to the first circuit board; A multilayer circuit board comprising: The single-sided metal-clad laminate is the metal-clad laminate of the present invention, and the bonding sheet and the second insulating resin layer (B) are laminated in contact with each other.

[0016] The electronic device of the present invention includes the multilayer circuit board of the present invention.

[0017] An electronic device of the present invention includes the multilayer circuit board of the present invention. [Effects of the Invention]

[0018] The metal-clad laminate of the present invention is suppressed from adhesion and curling during the heating process. Therefore, in circuit boards manufactured using the metal-clad laminate of the present invention, it is possible to improve yield and ensure reliability. Therefore, the metal-clad laminate of the present invention is particularly suitable for use as a circuit board material for FPCs and the like in electronic devices and electronic equipment. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing a cross-sectional structure in the thickness direction of a metal-clad laminate according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing a cross-sectional structure in the thickness direction of a metal-clad laminate according to another preferred embodiment of the present invention. [Figure 3] 1 is a schematic diagram showing a cross-sectional structure in the thickness direction of a multilayer circuit board to which a metal-clad laminate is applied. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings.

[0021] [Metal-clad laminate] FIG. 1 shows a cross-sectional configuration of a metal-clad laminate 100A according to a preferred embodiment of the present invention. The metal-clad laminate 100A includes a metal layer 110, a first insulating resin layer 40 laminated on one side of the metal layer 110, an adhesive layer AD laminated in contact with the first insulating resin layer 40, and a second insulating resin layer 50A laminated in contact with the adhesive layer AD. In the metal-clad laminate 100A, the first insulating resin layer 40, the adhesive layer AD, and the second insulating resin layer 50A are laminated in this order to form a resin laminate 101A. Therefore, the metal-clad laminate 100A has a structure in which the metal layer 110 is laminated on one side of the resin laminate 101A. In the metal-clad laminate 100A, the first insulating resin layer 40 corresponds to the first insulating resin layer (A) of the present invention, and the second insulating resin layer 50A corresponds to the second insulating resin layer (B) of the present invention. The symbols t1 to t4 indicate the thickness of each layer (the same applies to FIG. 2).

[0022] FIG. 2 shows a cross-sectional view of a metal-clad laminate 100B according to another preferred embodiment of the present invention. The metal-clad laminate 100B includes a metal layer 110, a first insulating resin layer 40 laminated on one side of the metal layer 110, an adhesive layer AD laminated in contact with the first insulating resin layer 40, and a second insulating resin layer 50B laminated in contact with the adhesive layer AD. The second insulating resin layer 50B has a layer structure in which a thermoplastic polyimide layer 60, a non-thermoplastic polyimide layer 70, and a thermoplastic polyimide layer 80 are laminated in this order. In the metal-clad laminate 100B, the first insulating resin layer 40, the adhesive layer AD, and the second insulating resin layer 50B are laminated in this order to form a resin laminate 101B. Therefore, the metal-clad laminate 100B has a structure in which a metal layer 110 is laminated on one side of the resin laminate 101B. In the metal-clad laminate 100B, the first insulating resin layer 40 corresponds to the first insulating resin layer (A) of the present invention, and the second insulating resin layer 50B corresponds to the second insulating resin layer (B) of the present invention.

[0023] The metal-clad laminates 100A and 100B may include any resin layer other than those described above, as long as the effect of the invention is not impaired.

[0024] In the metal-clad laminates 100A and 100B, the first insulating resin layer 40 and the second insulating resin layer 50A or 50B both satisfy the following conditions (I) to (III): (I) Storage modulus at 30°C is 1.0 x 10 9 Pa or greater; (II) The average thermal expansion coefficient from 250°C to 100°C is within the range of 10 to 30 ppm / K; (III) a glass transition temperature (Tg) of 180°C or higher; When metal-clad laminates 100A and 100B satisfy conditions (I) to (III), the mechanical properties required for circuit board materials are ensured, and curling can be suppressed when exposed to high temperatures during the circuit processing step. However, in the metal-clad laminates 100A and 100B, the second insulating resin layer 50A and the second insulating resin layer 50B differ from the first insulating resin layer 40 in one or more of their thickness, number of constituent layers, material, storage modulus, or thermal expansion coefficient.

[0025] In addition, the second insulating resin layer 50A and the second insulating resin layer 50B have a storage modulus of 1.0×10 in the temperature range of 30° C. to 200° C. in order to prevent adhesion when heated in a rolled state. 9 Pa or more, 1.0 × 10 9 Pa ~ 2.0 × 10 10 The storage modulus in the temperature range of 30°C to 200°C is preferably in the range of 1.0 × 10 9 If the compressive strength is less than Pa, the material will be softened by heating in the roll state, and adhesion will easily occur.

[0026] In addition, to prevent adhesion when heated in a rolled state, the storage modulus in the temperature range from 30°C to 200°C is set to 1.0 x 10 9 It is also preferable that the second insulating resin layer 50A and the second insulating resin layer 50B have an exposed surface made of a non-thermoplastic polyimide layer, instead of the electrical resistance being equal to or higher than Pa. In other words, it is preferable that the second insulating resin layer 50A or 50B has an exposed non-thermoplastic polyimide layer that is not easily softened by heat on the side opposite to the adhesive layer AD. Instead of forming the exposed surfaces of the second insulating resin layer 50A and the second insulating resin layer 50B as non-thermoplastic polyimide layers, it is also possible to incorporate a filler therein to reduce adhesion during heating and prevent adhesion.

[0027] In resin laminates 101A, 101B in which an adhesive layer AD is laminated between a first insulating resin layer 40 and a second insulating resin layer 50A or 50B, it is necessary to suppress curling caused by a difference in thermal stress that occurs between the first insulating resin layer 40 and the second insulating resin layer 50A or 50B due to heat applied during the production of the circuit board. For example, if curling occurs in the circuit board in a reflow device during solder mounting of the circuit board, there is a concern that lead lift of the element will occur, resulting in poor bonding. Therefore, in the metal-clad laminates 100A, 100B of the present invention, the bending moment (M A ) and the bending moment (M B ) absolute value of the difference (|M A -M B It is important that |) is less than 10 mNm. Here, since the curl due to heat is caused by the difference in bending moment between the first insulating resin layer 40 and the second insulating resin layer 50A or 50B via the adhesive layer AD, the absolute value |M A -M B |[mNm] is defined as the "curl index." If the curl index is 10 mNm or more, curling is likely to occur due to thermal stress during heating. If the curl index is less than 10 mNm, poor bonding due to curling will not occur. From this perspective, the curl index is more preferably 8 mNm or less.

[0028] Here, the bending moment M A ,M B can be calculated in the following way: First, the thermal stress σ generated in the first insulating resin layer 40 A [kPa] and the thermal stress σ generated in the second insulating resin layer 50A or 50B B [kPa] is expressed by the following formulas (1) and (2).

[0029]

number

[0030] In formulas (1) and (2), T2 is the maximum temperature during reflow; 260°C, T1 is the room temperature; 30°C, and α A is the coefficient of thermal expansion (CTE) of the first insulating resin layer 40, α B is the CTE of the second insulating resin layer 50A or 50B, E A is the storage modulus of the first insulating resin layer 40 at 30°C, E B is the storage modulus of the second insulating resin layer 50A or 50B at 30°C.

[0031] Next, the bending moment of the first insulating resin layer 40 caused by the thermal stress of formula (1) is defined as M A [mNm], the bending moment of the second insulating resin layer 50A or 50B caused by the thermal stress of formula (2) is M B [mNm], these bending moments are A ,σ B and the section modulus Z of the first insulating resin layer 40 A , the section modulus Z of the second insulating resin layer 50A or 50B B Therefore, it is expressed by equations (3) and (4).

[0032]

number

[0033] In formulas (3) and (4), b represents the cross-sectional width of the insulating resin layer, which is set to 1 m for convenience, t2 represents the thickness (unit: μm) of the first insulating resin layer 40, and t4 represents the thickness (unit: μm) of the second insulating resin layer 50A or 50B. The curl index is calculated by multiplying the bending moment M A [mNm] and the bending moment M of the second insulating resin layer 50A or 50B BThe target bending moment is [mNm] and does not take into consideration the presence of the metal layer 110. This is because in the reflow process stage, where curling is likely to occur, the metal layer 110 is often subjected to circuit wiring processing, and the difference in bending moment between the first insulating resin layer 40 and the second insulating resin layer 50A or 50B becomes the dominant factor in the occurrence of curling.

[0034] In order to reduce transmission loss of high frequency signals, the resin laminate 101A and the resin laminate 101B preferably have an overall dielectric loss tangent at 10 GHz of 0.0004 or less, more preferably 0.0036 or less, and even more preferably 0.0032 or less.

[0035] Next, each layer constituting the metal-clad laminates 100A and 100B will be described in more detail.

[0036] <Metal layer> The material of the metal layer 110 is not particularly limited, and 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 copper alloys are particularly preferred. The copper foil may be rolled copper foil or electrolytic copper foil, and commercially available copper foil can be used. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is the same as that of the metal layer 110. Furthermore, 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.

[0037] <Insulating resin layer> The resin constituting the first insulating resin layer 40 and the second insulating resin layers 50A, 50B is not particularly limited as long as it has electrical insulation properties and predetermined physical properties, and examples thereof include polyimide, epoxy resin, phenolic resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, ETFE, etc., with polyimide being preferred. 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, in addition to polyimide.

[0038] Furthermore, the first insulating resin layer 40 and the second insulating resin layers 50A, 50B may each be a single layer or may have a structure in which multiple resin layers are laminated. FIG. 1 shows a preferred example in which the first insulating resin layer 40 has a three-layer laminate structure of a thermoplastic polyimide layer 10, a non-thermoplastic polyimide layer 20, and a thermoplastic polyimide layer 30, and the second insulating resin layer 50A is a single non-thermoplastic polyimide layer. In this case, the metal-clad laminate 100A has a layer structure in which the metal layer 110 / thermoplastic polyimide layer 10 / non-thermoplastic polyimide layer 20 / thermoplastic polyimide layer 30 / adhesive layer AD / non-thermoplastic polyimide layer (the second insulating resin layer 50A) are laminated in this order. 2 shows a preferred example in which the first insulating resin layer 40 has a three-layer laminate structure of a thermoplastic polyimide layer 10, a non-thermoplastic polyimide layer 20, and a thermoplastic polyimide layer 30, and the second insulating resin layer 50B has a three-layer laminate structure of a thermoplastic polyimide layer 60, a non-thermoplastic polyimide layer 70, and a thermoplastic polyimide layer 80. In this case, the metal-clad laminate 100B has a layer structure in which the metal layer 110 / thermoplastic polyimide layer 10 / non-thermoplastic polyimide layer 20 / thermoplastic polyimide layer 30 / adhesive layer AD / thermoplastic polyimide layer 60 / non-thermoplastic polyimide layer 70 / thermoplastic polyimide layer 80 are laminated in this order. Even if the outermost layer having an exposed surface is the thermoplastic polyimide layer 80, the storage modulus in the temperature range from 30°C to 200°C is 1.0 x 10 9By setting the compressive strength to be equal to or greater than 100 Pa, adhesion during heating in a rolled state can be suppressed.

[0039] However, since Figures 1 and 2 are merely examples, the first insulating resin layer 40 and the second insulating resin layers 50A, 50B may be made of a material other than polyimide, and they do not need to have a single-layer or three-layer structure, but may each have two layers or four or more layers.

[0040] 1 and 2, the thermoplastic polyimide layers 10, 30, 60, and 80 may be made of the same or different types of thermoplastic polyimides. The non-thermoplastic polyimide layers 20 and 70 and the second insulating resin layer 50A, which is a non-thermoplastic polyimide layer, may also be made of the same or different types of non-thermoplastic polyimides.

[0041] The first insulating resin layer 40 and the second insulating resin layers 50A, 50B may contain, as appropriate, plasticizers, curable resin components such as epoxy resins, curing agents, curing accelerators, organic or inorganic fillers, coupling agents, flame retardants, etc.

[0042] Next, the non-thermoplastic polyimide and thermoplastic polyimide constituting the first insulating resin layer 40 and the second insulating resin layers 50A and 50B will be described. In the present invention, the term "non-thermoplastic polyimide" generally refers to a polyimide that does not soften or exhibit adhesiveness even when heated. In the present invention, however, the term "non-thermoplastic polyimide" refers to a polyimide having a storage modulus of 1.0×10 at 30°C measured using a dynamic viscoelasticity measuring device (DMA). 9 Pa or more, and the storage modulus at 300°C is 3.0 × 10 8 The term "thermoplastic polyimide" generally refers to a polyimide whose glass transition temperature (Tg) can be clearly confirmed. In the present invention, however, the term "thermoplastic polyimide" refers to a polyimide whose storage modulus at 30°C measured using a dynamic viscoelasticity measuring apparatus (DMA) is 1.0 × 10 8 Pa or more, and the storage modulus at 300°C is 3.0 × 10 7 Polyimides with a modulus of less than 1 Pa are also referred to as polyimides.

[0043] Non-thermoplastic polyimides: The polyimide used in the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 is preferably a non-thermoplastic polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride component with a diamine component containing an aliphatic diamine and / or an aromatic diamine. Monomers commonly used in the synthesis of non-thermoplastic polyimides can be used as the acid anhydride and diamine. However, the following examples are preferred in order to control the storage modulus and thermal expansion coefficient of the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 within appropriate ranges. By selecting the type of acid anhydride and diamine, or by selecting the respective molar ratios when two or more acid anhydrides or diamines are used, the thermal expansion properties, adhesion, storage modulus, glass transition temperature, and the like can be controlled.

[0044] The non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 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 acid dianhydride, and the diamine residue refers to a divalent group derived from a diamine compound. The non-thermoplastic polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic acid dianhydride and an aromatic diamine residue derived from an aromatic diamine.

[0045] (tetracarboxylic acid residue) The non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 preferably contains, as the tetracarboxylic acid residue, a tetracarboxylic acid residue derived from at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ), and a tetracarboxylic acid residue derived from at least one of pyromellitic dianhydride (PMDA) and 2,3,6,7-naphthalenetetracarboxylic dianhydride (NTCDA).

[0046] Tetracarboxylic acid residues derived from BPDA (hereinafter also referred to as "BPDA residues") and tetracarboxylic acid residues derived from TAHQ (hereinafter also referred to as "TAHQ residues") tend to form ordered polymer structures and reduce dielectric loss tangent and moisture absorption by suppressing molecular motion. BPDA residues can impart self-supporting properties to gel films as polyamic acids in polyimide precursors, but they also tend to increase the in-plane thermal expansion coefficient after imidization and lower the glass transition temperature, reducing heat resistance.

[0047] From this viewpoint, it is preferable to control the total content of BPDA residues and TAHQ residues in the non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 so that it is preferably 30 to 60 parts by mole, more preferably 40 to 50 parts by mole, per 100 parts by mole of all tetracarboxylic acid residues. If the total content of BPDA residues and TAHQ residues is less than 30 parts by mole, the formation of an ordered structure of the polymer may be insufficient, resulting in reduced moisture absorption resistance and insufficient reduction of the dielectric loss tangent. If the total content exceeds 60 parts by mole, the in-plane thermal expansion coefficient may increase and heat resistance may be reduced.

[0048] Furthermore, tetracarboxylic acid residues derived from pyromellitic dianhydride (hereinafter also referred to as "PMDA residues") and tetracarboxylic acid residues derived from 2,3,6,7-naphthalenetetracarboxylic dianhydride (hereinafter also referred to as "NTCDA residues") are rigid, enhancing in-plane orientation and lowering the in-plane thermal expansion coefficient, while also controlling the glass transition temperature. However, because PMDA residues have a low molecular weight, excessive amounts of them increase the imide group concentration in the polymer, increasing the polar groups and increasing hygroscopicity, leading to an increase in the dielectric loss tangent due to the influence of moisture within the molecular chain. Furthermore, NTCDA residues tend to make films brittle due to their highly rigid naphthalene skeleton, increasing the modulus of elasticity.

[0049] Therefore, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer preferably contains a total of 40 to 70 molar parts of PMDA residues and NTCDA residues, more preferably 50 to 60 molar parts, and even more preferably 50 to 55 molar parts, per 100 molar parts of all tetracarboxylic acid residues. If the total of PMDA residues and NTCDA residues is less than 40 molar parts, the in-plane thermal expansion coefficient may increase and heat resistance may decrease. If the total of PMDA residues and NTCDA residues exceeds 70 molar parts, the imide group concentration in the polymer may increase, resulting in an increase in polar groups, which may impair low moisture absorption, increase the dielectric loss tangent, and cause the film to become brittle and reduce its self-supporting ability.

[0050] The total amount of at least one of BPDA residue and TAHQ residue and at least one of PMDA residue and NTCDA residue is preferably 80 molar parts or more, and more preferably 90 molar parts or more, per 100 molar parts of all tetracarboxylic acid residues.

[0051] Furthermore, it is preferable to set the molar ratio of at least one of BPDA residues and TAHQ residues to at least one of PMDA residues and NTCDA residues {(BPDA residues + TAHQ residues) / (PMDA residues + NTCDA residues)} within a range of 0.4 to 1.5, preferably within a range of 0.6 to 1.3, and more preferably within a range of 0.8 to 1.2, in order to control the in-plane thermal expansion coefficient and the formation of an ordered structure of the polymer.

[0052] Because PMDA and NTCDA have a rigid backbone, they are able to control the in-plane molecular orientation in polyimides compared to other common acid anhydride components, suppressing the in-plane thermal expansion coefficient and improving the glass transition temperature (Tg). Furthermore, because BPDA and TAHQ have a larger molecular weight than PMDA, increasing their loading ratio reduces the imide group concentration, which is effective in lowering the dielectric tangent and moisture absorption rate. On the other hand, increasing the loading ratio of BPDA and TAHQ reduces the in-plane molecular orientation in polyimides, leading to an increase in the in-plane thermal expansion coefficient. Furthermore, the formation of an ordered structure within the molecules progresses, increasing the haze value.

[0053] Examples of tetracarboxylic acid residues other than the BPDA residue, TAHQ residue, PMDA residue, and NTCDA residue contained in the non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20 and 70 include 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic anhydride, 2,3',3,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-,2,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-diphenyl ether tetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3.4-dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid Dianhydrides, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1,4,5,8-(or 2,3,6,7-)tetracarboxylic dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, ethylene glycol Examples include tetracarboxylic acid residues derived from aromatic tetracarboxylic dianhydrides such as bisanhydrotrimellitate.

[0054] (diamine residue) The diamine residue contained in the non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 is preferably a diamine residue derived from a diamine compound represented by general formula (A1).

[0055] [ka]

[0056] In formula (A1), 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, an alkoxy group having 1 to 3 carbon atoms, 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 formula (A1), the multiple substituents Y and the integers p and q may be the same or different. In formula (A1), 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).

[0057] The diamine compound represented by general formula (A1) (hereinafter sometimes referred to as "diamine (A1)") is an aromatic diamine having one to three benzene rings. Diamine (A1) has a rigid structure, and therefore 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.

[0058] Examples of diamines (A1) 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).

[0059] The non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 preferably contains 80 molar parts or more, and more preferably 85 molar parts or more, of diamine residues derived from diamine (A1) relative to 100 molar parts of all diamine residues. By using diamine (A1) in an amount within the above range, an ordered structure is easily formed throughout the polymer due to the rigid structure derived from the monomer, and a non-thermoplastic polyimide having low gas permeability, low moisture absorption, and low dielectric loss tangent is easily obtained.

[0060] Furthermore, when the diamine residues derived from the diamine (A1) are in the range of 80 to 85 parts by mole relative to 100 parts by mole of all diamine residues in the non-thermoplastic polyimide, it is preferable to use 1,4-diaminobenzene as the diamine (A1) from the viewpoint of a more rigid structure with excellent in-plane orientation.

[0061] Other diamine residues contained in the non-thermoplastic polyimide constituting the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 include, for example, 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]ether ... aminophenoxy)]benzophenone, 9,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 2,2-bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3, 3'-Diaminobiphenyl, 3,3'-dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl)ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl- 5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, 1,Examples of the diamine residue include those derived from aromatic diamine compounds such as 3-bis[2-(4-aminophenyl)-2-propyl]benzene and 6-amino-2-(4-aminophenoxy)benzoxazole, and those derived from aliphatic diamine compounds such as dimer acid diamines in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

[0062] It is preferable that both the tetracarboxylic acid residue and the diamine residue contained in the non-thermoplastic polyimide are aromatic groups, since this can improve dimensional accuracy in a high-temperature environment.

[0063] Non-thermoplastic polyimides can be produced by reacting the above-mentioned tetracarboxylic dianhydride with a diamine compound in a solvent to produce polyamic acid, followed by heating and ring-closure. For example, approximately equimolar amounts of the tetracarboxylic dianhydride and the diamine compound are dissolved in an organic solvent and stirred at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours to cause a polymerization reaction, thereby producing polyamic acid, a precursor to polyimide. During the reaction, the reaction components are dissolved in the organic solvent so that the resulting precursor is in the range of 5 to 50 wt %, preferably 10 to 40 wt %, of the organic solvent. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, and cresol. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such organic solvents used is not particularly limited, but it is preferable to adjust the amount so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight.

[0064] The synthesized polyamic acid is usually advantageously used as a solution in a reaction solvent, but it can be concentrated, diluted, or replaced with another organic solvent if necessary. Polyamic acid is also advantageously used because it generally has excellent solvent solubility. The viscosity of the polyamic acid solution is preferably within the range of 500 mPa·s to 100,000 mPa·s. If the viscosity is outside this range, defects such as uneven thickness and streaks are likely to occur in the film during coating using a coater or the like.

[0065] The method for imidizing polyamic acid to form a non-thermoplastic polyimide is not particularly limited, and a heat treatment such as heating at a temperature in the range of 80 to 400° C. for 1 to 24 hours is preferably used.

[0066] The weight-average molecular weight of the non-thermoplastic polyimide is, for example, preferably in the range of 10,000 to 400,000, more preferably in the range of 50,000 to 350,000. If the weight-average molecular weight is less than 10,000, the film tends to have reduced strength and become brittle. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur during coating.

[0067] From the viewpoint of heat resistance, the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 preferably have a glass transition temperature (Tg) of 280°C or higher, and more preferably 300°C or higher.

[0068] Furthermore, from the viewpoint of suppressing curling, the average thermal expansion coefficient from 250°C to 100°C in the in-plane direction perpendicular to the thickness direction of the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 is preferably in the range of 1 ppm / K or more and 30 ppm / K or less, more preferably in the range of 1 ppm / K or more and 25 ppm / K or less, and even more preferably in the range of 15 ppm / K or more and 25 ppm / K or less.

[0069] In addition, the non-thermoplastic polyimide used in the second insulating resin layer 50A and the non-thermoplastic polyimide layers 20, 70 may contain optional components such as plasticizers, other curable resin components such as epoxy resins, curing agents, curing accelerators, coupling agents, fillers, and flame retardants.

[0070] Thermoplastic polyimide: The polyimide used in the thermoplastic polyimide layers 10, 30, 60, and 80 is preferably a thermoplastic polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride component with an aliphatic diamine and / or an aromatic diamine. Monomers commonly used in the synthesis of thermoplastic polyimides can be used as the acid anhydride and diamine. However, the following examples are preferred in order to control the storage modulus of the thermoplastic polyimide layers 10, 30, 60, and 80 within an appropriate range. By selecting the type of acid anhydride and diamine, or the molar ratio when using two or more acid anhydrides or diamines, it is possible to control the thermal expansion, adhesion, storage modulus, glass transition temperature, and other properties. Furthermore, from the viewpoint of improving dielectric properties, it is also preferable to use an adhesive polyimide for forming the adhesive layer AD as the polyimide used in the thermoplastic polyimide layers 10, 30, 60, and 80.

[0071] The thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80 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.

[0072] (tetracarboxylic acid residue) The tetracarboxylic acid residue used in the thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80 may be the same as those exemplified as the tetracarboxylic acid residue in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layers 20 and 70 and the second insulating resin layer 50A.

[0073] (diamine residue) The diamine residue contained in the thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80 is preferably a diamine residue derived from a diamine compound represented by any of the general formulae (B1) to (B7).

[0074] [ka]

[0075] 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).

[0076] 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-. 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.

[0077] 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. Examples of diamine (B2) include 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzeneamine, and 3-[3-(4-aminophenoxy)phenoxy]benzeneamine.

[0078] 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. 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.

[0079] 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-. 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. Examples of diamine (B5) include 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline and 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline.

[0081] 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 polyimide. Here, the linking group A is preferably -C(CH3)2-, -O-, -SO2-, or -CO-. 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).

[0082] 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. Examples of diamine (B7) include bis[4-(3-aminophenoxy)]biphenyl and bis[4-(4-aminophenoxy)]biphenyl.

[0083] The thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80 preferably contains at least 60 molar parts, preferably at least 60 molar parts and at most 99 molar parts, more preferably at least 70 molar parts and at most 95 molar parts, of diamine residues derived from one or more diamine compounds selected from diamines (B1) to (B7) relative to 100 molar parts of all 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 can improve the flexibility of the polyimide molecular chain and impart thermoplasticity. If the total amount of diamine residues derived from one or more diamine compounds selected from diamines (B1) to (B7) is less than 60 molar parts relative to 100 molar parts of all diamine components, the polyimide resin will lack flexibility and will not exhibit sufficient thermoplasticity.

[0084] Furthermore, diamine residues derived from diamine compounds represented by the general formula (A1) are also preferred as diamine residues contained in the thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80. The diamine compound represented by formula (A1) [diamine (A1)] is as described in the description of non-thermoplastic polyimides. Diamine (A1) has a rigid structure and acts to impart an ordered structure to the entire polymer, thereby suppressing molecular motion and thereby 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 adhesion can be obtained.

[0085] The thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80 may contain diamine residues derived from diamine (A1) in an amount preferably ranging from 1 to 40 parts by mole, more preferably from 5 to 30 parts by mole. By using diamine (A1) 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 adhesion.

[0086] The thermoplastic polyimide constituting the thermoplastic polyimide layers 10, 30, 60, and 80 may contain diamine residues derived from diamine compounds other than the diamines (A1) and (B1) to (B7) within the scope that does not impair the effects of the invention.

[0087] 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 two or more types of tetracarboxylic acid residues or diamine residues. When the thermoplastic polyimide has a plurality of polyimide structural units, they may be present as blocks or randomly, but are preferably present randomly.

[0088] By making both the tetracarboxylic acid residue and the diamine residue contained in the thermoplastic polyimide aromatic groups, the dimensional accuracy in a high temperature environment can be improved.

[0089] Thermoplastic polyimides and their precursors can be synthesized in the same manner as non-thermoplastic polyimides.

[0090] The weight-average molecular weight of the thermoplastic polyimide is preferably in the range of 10,000 to 400,000, and more preferably in the range of 50,000 to 350,000. If the weight-average molecular weight is less than 10,000, the film tends to have reduced strength and become brittle. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur during coating.

[0091] From the viewpoint of exhibiting adhesiveness to metal foil and other insulating layer materials, the thermoplastic polyimide layers 10, 30, 60, and 80 preferably have a glass transition temperature (Tg) in the range of 150°C or higher and lower than 300°C, more preferably 200 to 290°C, and most preferably 200 to 280°C.

[0092] In order to suppress curling, the thermoplastic polyimide layers 10, 30, 60, and 80 preferably have an average thermal expansion coefficient in the in-plane direction perpendicular to the thickness direction from 250°C to 100°C of 30 ppm / K or more, preferably in the range of 30 ppm / K to 100 ppm / K, and more preferably in the range of 30 ppm / K to 80 ppm / K.

[0093] In addition to polyimide, the resin used for the thermoplastic polyimide layers 10, 30, 60, and 80 may contain optional components such as plasticizers, other curable resin components such as epoxy resins, curing agents, curing accelerators, inorganic fillers, coupling agents, bulking agents, and flame retardants.

[0094] <Adhesive layer> The material of the adhesive layer AD is preferably, for example, a thermoplastic resin or a thermosetting resin, such as a polyimide resin, a polyamide resin, an epoxy resin, a phenoxy resin, an acrylic resin, a polyurethane resin, a styrene resin, a polyester resin, a phenolic resin, a polysulfone resin, a polyethersulfone resin, a polyphenylene sulfide resin, a polyethylene resin, a polypropylene resin, a silicone resin, a polyetherketone resin, a polyvinyl alcohol resin, a polyvinyl butyral resin, a styrene-maleimide copolymer, a maleimide-vinyl compound copolymer, or a (meth)acrylic copolymer, an epoxy resin, a benzoxazine resin, a bismaleimide resin, and a cyanate ester resin.

[0095] When the adhesive layer AD 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.

[0096] The adhesive layer AD may be any of the following (i) to (iii); (i) The storage modulus at 50°C is 1800 MPa or less; (ii) the maximum storage modulus in the temperature range from 180°C to 260°C is 800 MPa or less; (iii) a glass transition temperature (Tg) of 180°C or less; It is preferable that the following conditions are satisfied. By satisfying conditions (i) and (ii), stress generation due to thermal expansion and contraction in an environment where the film is repeatedly exposed to low to high temperatures can be suppressed, and thermocompression bonding at 180°C or less is possible, ensuring adhesion and suppressing dimensional change after circuit processing. From these viewpoints, the storage modulus at 50°C is preferably 1000 MPa or less, and more preferably in the range of 1 to 500 MPa. Furthermore, the adhesive layer AD preferably has a maximum storage modulus of 800 MPa or less in the temperature range of 150°C to 260°C, more preferably has a maximum storage modulus of 800 MPa or less in the temperature range of 125°C to 260°C, and most preferably has a maximum storage modulus of 800 MPa or less in the temperature range of 100°C to 260°C. Furthermore, by satisfying the condition (iii), thermocompression bonding at low temperatures can be ensured. The glass transition temperature (Tg) of the adhesive layer AD is preferably 150°C or lower, more preferably 125°C or lower, and most preferably 100°C or lower.

[0097] The adhesive layer AD may have an average thermal expansion coefficient of more than 30 ppm / K from 250°C to 100°C in an in-plane direction perpendicular to the thickness direction. Because the adhesive layer AD has low elasticity, it can alleviate internal stress generated during lamination even if the thermal expansion coefficient in the in-plane direction exceeds 30 ppm / K.

[0098] A preferred example of the resin constituting the adhesive layer AD is a thermoplastic polyimide having adhesive properties (hereinafter, sometimes referred to as "adhesive polyimide"), which contains a tetracarboxylic acid residue derived from a tetracarboxylic acid anhydride and a diamine residue derived from a diamine compound.

[0099] (tetracarboxylic acid residue) The adhesive polyimide can contain, without particular limitation, tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides generally used in thermoplastic polyimides, but preferably contains a total of 90 molar parts or more of tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formula (1) (hereinafter sometimes referred to as "tetracarboxylic acid residues (1)") relative to 100 molar parts of all tetracarboxylic acid residues. By containing a total of 90 molar parts or more of tetracarboxylic acid residues (1) relative to 100 molar parts of all tetracarboxylic acid residues, it is easy to achieve both flexibility and heat resistance of the adhesive polyimide, and this is preferred. If the total amount of tetracarboxylic acid residues (1) is less than 90 molar parts, the solvent solubility of the adhesive polyimide tends to decrease.

[0100] [ka]

[0101] In general formula (1), X represents a single bond or a divalent group selected from the following formulae:

[0102] [ka]

[0103] In the above formula, Z represents -C6H4-, -(CH2)n- or -CH2-CH(-OC(=O)-CH3)-CH2-, where n represents an integer of 1 to 20.

[0104] Examples of tetracarboxylic acid dianhydrides for deriving the tetracarboxylic acid residue (1) include 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 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 bisanhydrotrimellitate (TMEG).

[0105] The adhesive polyimide may contain tetracarboxylic acid residues derived from acid anhydrides other than the tetracarboxylic acid anhydride represented by the general formula (1) above, provided that the effects of the invention are not impaired. Examples of such tetracarboxylic acid residues include, but are not limited to, pyromellitic dianhydride, 1,4-phenylenebis(trimellitic acid monoester)dianhydride, 2,3',3,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'- or 2,3,3',4'-benzophenonetetracarboxylic acid dianhydride, 2,3',3,4'-diphenylethertetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''-, or 2,2'',3,3''-p-terphenyltetracarboxylic acid dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)propane dianhydride, and bis(2,3- or 3,4-dicarboxyphenyl)propane dianhydride.4-dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride Examples of suitable tetracarboxylic acid residues include tetracarboxylic acid residues derived from aromatic tetracarboxylic acid dianhydrides such as hydrates, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1,4,5,8-(or 2,3,6,7-)tetracarboxylic acid dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, and 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride.

[0106] (diamine residue) The adhesive polyimide preferably contains 50 or more, preferably 60 or more, more preferably 80 or more, molar parts of diamine residues (hereinafter sometimes referred to as "dimer acid type diamine residues") derived from a dimer diamine composition primarily composed of a dimer diamine in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, relative to 100 molar parts of all diamine residues. The inclusion of the dimer acid type diamine residues in the above amounts improves the dielectric properties of the adhesive layer AD, improves thermocompression bonding properties by lowering the glass transition temperature (Tg) of the adhesive layer AD, and alleviates internal stress by lowering the elastic modulus. If the dimer acid type diamine residues are less than 50 molar parts relative to 100 molar parts of all diamine residues, the adhesive layer AD interposed between the first insulating resin layer 40 and the second insulating resin layers 50A and 50B may not have sufficient adhesive properties. Furthermore, the high elastic modulus of the adhesive layer AD, which has high thermal expansion, may impair dimensional stability.

[0107] Here, the dimer diamine composition is a mixture containing the following component (a) as a main component and optionally containing component (b) and component (c), and is a purified product in which the amounts of component (b) and component (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).

[0108] 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.

[0109] 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.

[0110] The dimer diamine composition used should be one in which the dimer diamine content of component (a) is increased to 96% or more, preferably 97% or more, and more preferably 98% or more, in terms of area percentage in a chromatogram obtained by GPC measurement, by a purification method such as molecular distillation. By increasing the dimer diamine content of component (a) to 96% or more, broadening of the molecular weight distribution of the polyimide can be suppressed. If technically possible, it is best for all (100%) of the dimer diamine composition 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.

[0111] 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.

[0112] The adhesive polyimide may contain a diamine residue other than the dimer acid type diamine residue described above, provided that the effects of the present invention are not impaired. Examples of such a diamine residue include diamine residues derived from the diamine compounds exemplified above as those used in the thermoplastic polyimide.

[0113] In the adhesive 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 adhesive polyimide has a plurality of polyimide structural units, they may be present as blocks or randomly, but are preferably present randomly.

[0114] The weight-average molecular weight of the adhesive polyimide is 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 AD tends to decrease and the adhesive layer AD 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 AD tends to have defects such as uneven thickness and streaks during coating.

[0115] The adhesive 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 the polyimide thin film by the 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.

[0116] (Crosslink formation) When an adhesive 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 C=N bond, thereby forming a crosslinked structure. The formation of a crosslinked structure can improve the heat resistance of the adhesive polyimide. Examples of tetracarboxylic acid anhydrides suitable for forming adhesive polyimides having ketone groups include 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), and examples of diamine compounds include aromatic diamines such as 4,4'-bis(3-aminophenoxy)benzophenone (BABP) and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB).

[0117] Examples of amino compounds that can be used to crosslink adhesive 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.

[0118] The adhesive polyimide and its precursor can be synthesized in the same manner as for the non-thermoplastic polyimide.

[0119] To crosslink the adhesive polyimide obtained as described above, the amino compound is added to a resin solution containing an adhesive polyimide having ketone groups, and the ketone groups in the adhesive polyimide and the primary amino groups 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 an amount such that the total number of primary amino groups per mole of ketone groups 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 less than 0.004 moles, the adhesive polyimide will not be sufficiently crosslinked by the amino compound, resulting in a tendency for the adhesive layer AD to exhibit poor heat resistance after curing. However, if the amount of amino compound added exceeds 1.5 moles, the unreacted amino compound will act as a thermoplasticizer, reducing the heat resistance of the adhesive layer AD.

[0120] The conditions for the condensation reaction for crosslinking are not particularly limited, as long as they are conditions under which the ketone group in the adhesive polyimide reacts with the primary amino group of the amino compound to form an imine bond (C=N bond). The temperature for the thermal condensation is preferably within the range of, for example, 120 to 220°C, more preferably within the range of 140 to 200°C, for reasons such as discharging water produced by the condensation outside the system or simplifying the condensation step when the thermal condensation reaction is carried out subsequently to the synthesis of the adhesive polyimide. The reaction time is preferably about 30 minutes to 24 hours, and 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.

[0121] The thermal condensation of the ketone group of the adhesive polyimide with the primary amino group of the amino compound can be carried out, for example, by (a) adding an amino compound and heating the mixture following the synthesis (imidization) of the adhesive polyimide, (b) charging an excess amount of an amino compound as a diamine component in advance, and then heating the adhesive polyimide together with the remaining amino compound that is not involved in the imidization or amidation following the synthesis (imidization) of the adhesive polyimide, or (c) processing the adhesive 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) and then heating it, or the like.

[0122] The formation of imine bonds has been described as a method for forming a crosslinked structure to impart heat resistance to adhesive polyimides, but the present invention is not limited to this. For example, an adhesive polyimide can be cured by blending an epoxy resin, an epoxy resin curing agent, or the like.

[0123] By using the adhesive polyimide obtained as described above, the adhesive layer AD has excellent flexibility and dielectric properties (low dielectric constant and low dielectric loss tangent).

[0124] <Layer thickness> In the metal-clad laminates 100A and 100B, the thickness t1 of the metal layer 110 is not particularly limited, but when a metal foil such as a copper foil is used, the thickness is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoints of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm.

[0125] When the thickness of the resin laminate 101A, 101B (i.e., the total thickness of the first insulating resin layer 40, adhesive layer AD, and second insulating resin layer 50A or 50B) is T, the metal-clad laminate 100A, 100B preferably has a thickness T in the range of 70 to 500 μm, more preferably 100 to 300 μm. If the thickness T 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, productivity may decrease.

[0126] The thickness t3 of the adhesive layer AD is preferably, for example, in the range of 50 to 450 μm, and more preferably in the range of 50 to 250 μm. If the thickness t3 of the adhesive layer AD is less than the above-mentioned lower limit, the dielectric loss tangent will be insufficient, sufficient dielectric properties will not be obtained, and sufficient adhesion to the insulating resin layer will be difficult to obtain. On the other hand, if the thickness of the adhesive layer AD exceeds the above-mentioned upper limit, problems such as reduced dimensional stability will occur.

[0127] Furthermore, the ratio (t3 / T) of the thickness t3 of the adhesive layer AD to the thickness T is preferably in the range of 0.5 to 0.96, more preferably in the range of 0.5 to 0.75. If the ratio (t3 / T) is less than 0.5, the dielectric loss tangent is not sufficiently reduced, and sufficient dielectric properties cannot be obtained. If it exceeds 0.96, problems such as reduced dimensional stability occur.

[0128] The thickness t2 of the first insulating resin layer 40 and the thickness t4 of the second insulating resin layers 50A, 50B are each, for example, preferably in the range of 8 to 50 μm, more preferably in the range of 12 to 50 μm, even more preferably in the range of 20 to 50 μm, and most preferably in the range of 38 to 45 μm. If the thicknesses t2 and t4 are less than the above lower limit values, problems such as curling may occur in the metal-clad laminates 100A, 100B. If the thicknesses t2 and t4 exceed the above upper limit values, problems such as reduced transmission characteristics may occur when the resulting circuit board is used.

[0129] Furthermore, thicknesses t2 and t4 do not necessarily have to be the same, but from the viewpoint of effectively suppressing curling, the ratio of thickness t4 to thickness t2 (t4 / t2) is preferably within the range of 0.5 to 2.0, more preferably within the range of 0.6 to 1.5. If the ratio (t4 / t2) is outside the above range, curling is more likely to occur.

[0130] The thickness of the non-thermoplastic polyimide layers 20, 70 is preferably in the range of 6 μm to 45 μm, more preferably in the range of 9 μm to 30 μm, from the viewpoints of ensuring the function as a base layer and transportability during production and thermoplastic polyimide coating. If the thickness of the non-thermoplastic polyimide layers 20, 70 is less than the above lower limit, electrical insulation and handleability become insufficient, while if it exceeds the above upper limit, productivity decreases.

[0131] From the viewpoint of ensuring adhesive properties, the thickness of each of the thermoplastic polyimide layers 10, 30, 60, and 80 is preferably in the range of 1 μm to 10 μm, more preferably in the range of 1 μm to 5 μm. If the thickness of the thermoplastic polyimide layers 10, 30, 60, and 80 is less than the lower limit, adhesiveness becomes insufficient, and if the thickness exceeds the upper limit, dimensional stability tends to deteriorate.

[0132] [Manufacturing of metal-clad laminates] Although not shown, the metal-clad laminates 100A and 100B can be produced, for example, according to the following method 1 or method 2. The adhesive polyimide that forms the adhesive layer AD may be crosslinked as described above.

[0133] <Method 1> A method in which the above-mentioned adhesive polyimide or its precursor that will become the adhesive layer AD is formed into a sheet to form an adhesive sheet, and the adhesive sheet is placed between the first insulating resin layer 40 of a single-sided metal-clad laminate formed by laminating a metal layer 110 and a first insulating resin layer 40 and a resin film that will become the second insulating resin layers 50A, 50B, and bonded together by thermocompression.

[0134] <Method 2> A method in which a solution of the adhesive polyimide or a solution of its precursor, which will become the adhesive layer AD, is applied to a predetermined thickness and dried on either the first insulating resin layer 40 of a single-sided metal-clad laminate formed by laminating a metal layer 110 and a first insulating resin layer 40, or on one or both of the resin films which will become the second insulating resin layers 50A, 50B, and then the coated film side is bonded together and thermocompressed.

[0135] The single-sided metal-clad laminate used in methods 1 and 2 can be produced, for example, by repeating a process of applying a polyamic acid solution onto a metal foil and drying it a predetermined number of times, followed by imidization. The adhesive sheet or resin film used in Method 1 can be produced, for example, by (1) applying a solution of polyamic acid to any supporting substrate, drying the solution, heat-treating it to form an imidized film, and then peeling it off from the supporting substrate to form an adhesive sheet or resin film; (2) applying a solution of polyamic acid to any supporting substrate, drying the solution, peeling the polyamic acid gel film from the supporting substrate, and heat-treating it to form an imidized film to form an adhesive sheet or resin film; or (3) applying a solution of the adhesive polyimide to a supporting substrate, drying the solution, and then peeling it off from the supporting substrate to form an adhesive sheet or resin film. Furthermore, in the above, the method for applying the polyimide solution (or polyamic acid solution) onto the metal foil, the supporting substrate, the first insulating resin layer 40, or the resin film is not particularly limited, and it is possible to apply it using, for example, a coater such as a comma, a die, a knife, or a lip.

[0136] Metal-clad laminates 100A and 100B of the present embodiment obtained as described above can be used to manufacture circuit boards such as single-sided FPCs by processing metal layer 110 into wiring circuits by etching or the like.

[0137] [Circuit board] A circuit board according to one embodiment of the present invention can be manufactured by forming a wiring layer by patterning the metal layer 110 of a metal-clad laminate 100A or 100B using a conventional method. For example, referring to FIG. 1 , the circuit board according to this embodiment includes a wiring layer formed by circuit processing the metal layer 110, a first insulating resin layer 40 laminated on at least one surface of the wiring layer, an adhesive layer AD laminated in contact with the first insulating resin layer 40, and a second insulating resin layer 50A laminated in contact with the adhesive layer AD. Referring to FIG. 2 , the circuit board according to this embodiment includes a wiring layer formed by circuit processing the metal layer 110, a first insulating resin layer 40 laminated on at least one surface of the wiring layer, an adhesive layer AD laminated in contact with the first insulating resin layer 40, and a second insulating resin layer 50B laminated in contact with the adhesive layer AD.

[0138] The circuit board of this embodiment can be preferably used as, for example, an FPC or a rigid-flex circuit board.

[0139] The metal-clad laminates 100A and 100B can also be preferably applied to multilayer circuit boards. FIG. 3 shows an example of a cross-sectional configuration of a multilayer circuit board 200 incorporating the metal-clad laminate 100A. The multilayer circuit board 200 is formed by laminating the metal-clad laminate 100A and a circuit board 120 with a bonding sheet BS interposed therebetween. The circuit board 120 includes a metal layer 210, an insulating resin layer 220 laminated on the metal layer 210, and a patterned wiring layer 230 laminated on the insulating resin layer 220. The multilayer circuit board 200 can be manufactured, for example, by arranging the wiring layer 230 of the circuit board 120 and the second insulating resin layer 50A of the metal-clad laminate 100A so that they face each other, and then placing a bonding sheet BS between them and thermocompression bonding them. The metal layer 110 and / or the metal layer 210 may be subjected to circuit processing before or after the multilayer circuit board 200 is manufactured.

[0140] Although not shown, metal-clad laminate 100B can also be applied to a multilayer circuit board in the same manner as metal-clad laminate 100A.

[0141] [Electronic Devices and Electronic Equipment] The electronic devices and electronic equipment according to the embodiments of the present invention include the above-described circuit board. Examples of the electronic devices of the present invention include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as organic EL lighting, solar cells, touch panels, camera modules, inverters, converters, and components thereof. Examples of the electronic equipment include hard disk drives, DVDs, mobile phones, smartphones, tablet devices, automotive electronic control units (ECUs), and power control units (PCUs). Circuit boards are preferably used in these electronic devices and electronic equipment as components such as wiring for moving parts, cables, and connectors. [Example]

[0142] 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.

[0143] [Measurement of coefficient of thermal expansion (CTE)] Using a thermomechanical analyzer (manufactured by Bruker, product name: 4000SA), a 3 mm x 20 mm polyimide film was heated from 30°C to 300°C at a constant heating rate while applying a 5.0 g load, and then held at that temperature for 10 minutes. After that, the film was cooled at a rate of 5°C / min, and the average thermal expansion coefficient (thermal expansion coefficient) from 250°C to 100°C was determined.

[0144] [Measurement of copper foil surface roughness] Using an AFM (manufactured by Bruker AXS, product name: Dimension Icon SPM) and a probe (manufactured by Bruker AXS, product name: TESPA (NCHV), tip curvature radius 10 nm, spring constant 42 N / m), measurements were taken in tapping mode over an area of ​​80 μm × 80 μm on the copper foil surface, and the ten-point average roughness (Rzjis) was calculated.

[0145] [Viscosity measurement] The viscosity 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.

[0146] [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 was used.) Polystyrene was used as a standard substance, and tetrahydrofuran (THF) was used as a developing solvent.

[0147] [Measurement of dielectric loss tangent (Df)] The dielectric loss tangent (Df) of the resin sheet at 10 GHz was measured using a vector network analyzer (Agilent, product name E8363C) and an SPDR resonator. The resin sheet used for the measurement was a resin laminate obtained by removing the metal layer from a single-sided metal-clad laminate, and was left for 72 hours under conditions of temperature: 24 to 26°C and humidity: 45°C to 55% RH.

[0148] [Measurement of storage modulus and glass transition temperature (Tg)] The storage modulus was measured using a 5 mm × 70 mm polyimide film using a dynamic viscoelasticity measuring device (DMA: manufactured by TA Instruments, product name: RSA G2) at a heating rate of 4°C / min from 30°C to 400°C and a frequency of 1 Hz. The peak value of Tan δ at the maximum temperature during the measurement was defined as the glass transition temperature (Tg).

[0149] [Evaluation of stickiness] Two single-sided metal-clad laminates were stacked so that the copper foil surface of one laminate contacted the insulating resin layer surface of the other laminate. They were then thermocompressed for 45 minutes at 150°C and 3.0 MPa using a hot press (Kitagawa Seiki Co., Ltd., product name: KVHC). After thermocompression bonding, the specimens were cut into 10 mm wide x 70 mm long test pieces. One copper foil surface was attached to an aluminum plate with double-sided tape. The laminate was peeled at the interface using a Tensilon tester (Toyo Seiki Seisakusho, product name: Strograph VE-1D). The other unattached single-sided metal-clad laminate was pulled in a 180° direction at a rate of 50 mm / min, and the median peel strength was measured after 10 mm of peeling. A value of 0.1 kN / m or greater was considered to be "sticky" ("Positive"), and a value of less than 0.1 kN / m was considered to be "non-sticky" ("Good").

[0150] [Film curl evaluation] The copper foil of a single-sided metal-clad laminate was etched to obtain a resin film, which was then cut to a size of 50 mm x 50 mm. The sample was left for 24 hours under conditions of temperature: 24-26°C, humidity: 45°C-55%RH. The heights of the four corners of the sample were measured with calipers, and the average value was taken as the amount of film curl. A film curl of 10 mm or more was judged as having film curl (×), and a film curl of less than 10 mm was judged as not having film curl (◯).

[0151] [Evaluation of curl during reflow] The copper foil of a single-sided metal-clad laminate was etched to obtain a resin film, which was then cut to a size of 50 mm x 50 mm. The sample was then heat-treated in a reflow machine (Antom Corporation, product name: UNI-6116S) under conditions of 100°C for 40 seconds, 150°C for 40 seconds, 200°C for 40 seconds, and 260°C for 70 seconds. The heights of the four corners of the sample were measured with calipers immediately after the treatment, and the average value was used as the curl amount. A curl amount of 10 mm or more was judged as "curl present" (×), and a curl amount of less than 10 mm was judged as "no curl present" (◯).

[0152] [Calculating the Carl Index] In a laminate in which an adhesive layer is laminated between a first insulating resin layer (A) and a second insulating resin layer (B), it is necessary to consider curling that occurs due to the difference in thermal stress that occurs in the first insulating resin layer (A) and the second insulating resin layer (B) due to the heat applied when creating a circuit board. For example, when soldering a circuit board, if the stress difference is large in the solder reflow equipment, the circuit board will curl in the reflow equipment, causing the leads of the element to lift, resulting in poor bonding. At this time, the thermal stress σ generated in the first insulating resin layer (A) A [kPa], thermal stress σ generated in the second insulating resin layer (B) B [kPa] is expressed by equations (1) and (2).

[0153]

number

[0154] The bending moment of each insulating resin layer caused by the thermal stress in formula (1) and formula (2) is M A , M B [mNm], these bending moments are the thermal stress σ and the section modulus Z of the first insulating resin layer (A) and the second insulating resin layer (B). A , Z B Therefore, it is expressed by equations (3) and (4).

[0155]

number

[0156] Here, b represents the cross-sectional width of each insulating resin layer, which is assumed to be 1 m for convenience, t2 represents the thickness of the first insulating resin layer (A), and t4 represents the thickness of the second insulating resin layer (B).

[0157] The curl of the laminate due to heat is caused by the difference in bending moment between the first insulating resin layer (A) and the second insulating resin layer (B) via the adhesive. Therefore, the absolute value of the difference in bending moment between the two layers |M A -M B |[mNm] is defined as the "curl index", and if the curl index is less than 10 mNm, no bonding failure due to curling occurs.

[0158] The abbreviations used in the examples and comparative examples represent the following compounds. BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PMDA: Pyromellitic dianhydride DDA: aliphatic diamine having 36 carbon atoms [manufactured by Croda Japan Co., Ltd., trade name: PRIAMINE 1074, distilled and purified, amine value: 210 mg KOH / g, mixture of dimer diamines with cyclic and chain structures, component (a): 97.9%, component (b): 0.3%, component (c): 1.8%] The "%" for component (a), component (b), and component (c) refers to the area percentage of the chromatogram in GPC measurement. The molecular weight of DDA was calculated using the following formula: molecular weight = 56.1 x 2 x 1000 / amine value. 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 N-12: Dodecanedioic acid dihydrazide NMP: N-methyl-2-pyrrolidone DMAc: N,N-dimethylacetamide OP945: organic phosphinic acid aluminum salt (manufactured by Clariant Japan, trade name: Exolit OP945, D 50 ;2.1μm, D 953.0 μm, maximum particle size: 6.7 μm, percentage of particles with a size exceeding 10 μm: 0% by volume

[0159] (Synthesis Example 1) <Preparation of resin solution for adhesive layer> Under a nitrogen stream, a reaction vessel was charged with 45.43 parts by weight of BTDA (0.1410 parts by mole), 74.57 parts by weight of DDA (0.1396 parts by mole), 168 parts by weight of NMP, and 112 parts by weight of xylene, and the mixture was thoroughly mixed at 40°C for 1 hour to prepare a polyamic acid solution. The polyamic acid solution was heated to 190°C and stirred for 5 hours, and 98 parts by weight of xylene was added to complete the imidization, preparing Polyimide Solution 1 (solid content: 30% by weight, weight average molecular weight: 52,800).

[0160] (Synthesis Example 2) <Preparation of polyamic acid solution for insulating resin layer> Under a nitrogen atmosphere, 64.20 parts by weight of m-TB (0.302 mol parts), 5.48 parts by weight of bisaniline-M (0.016 mol parts), and an amount of DMAc to achieve a solids concentration of 15% by weight after polymerization were added to a reactor and stirred at room temperature. Next, 34.20 parts by weight of PMDA (0.157 mol parts) and 46.13 parts by weight of BPDA (0.157 mol parts) were added, and the polymerization reaction was continued with stirring at room temperature for 3 hours to prepare polyamic acid solution 1 (viscosity: 26,500 mPa s).

[0161] (Synthesis Example 3) <Preparation of polyamic acid solution for insulating resin layer> Under a nitrogen atmosphere, 69.56 parts by weight of m-TB (0.328 mol), 542.75 parts by weight of TPE-R (1.857 mol), and an amount of DMAc to achieve a solids concentration of 12% by weight were added to a reaction vessel and stirred at room temperature. Next, 194.39 parts by weight of PMDA (0.891 mol), and 393.31 parts by weight of BPDA (1.337 mol) were added, and the polymerization reaction was continued with stirring at room temperature for 3 hours to prepare polyamic acid solution 2 (viscosity: 2,650 mPa s).

[0162] (Combination example 1) 100.00 parts by weight of polyimide solution 1 was blended with 9.40 parts by weight of N-12, diluted with 143.23 parts by weight of OP945 (55.00 parts by weight based on 100 parts by weight of the final resin), 95.44 parts by weight of xylene, and 17.18 parts by weight of NMP, and stirred in a planetary mixer. 768.06 parts by weight of polyimide solution 1 and 36.78 parts by weight of xylene were then added and stirred for 2 hours to prepare a resin composition for adhesive layers (viscosity: 2,477 mPa·s). This resin composition for adhesive layers was applied to a substrate, dried, and peeled off. The resulting adhesive film had a storage modulus of 90 MPa at 50°C, a maximum storage modulus of 3.5 MPa in the temperature range from 180°C to 260°C, and a glass transition temperature (Tg) of 52°C.

[0163] (Production Example 1) <Preparation of Single-Sided Metal-Clad Laminate Intermediate A> Polyamic acid solution 2 was uniformly applied onto electrolytic copper foil (thickness: 12 μm, surface roughness Rzjis on the resin layer side: 0.6 μm) to a thickness of approximately 1 to 2 μm after curing, and then heated and dried at 120°C to remove the solvent. Next, polyamic acid solution 1 was uniformly applied onto that to a thickness of approximately 5 μm after curing, and then heated and dried at 120°C to remove the solvent. Polyamic acid solution 2 was further uniformly applied onto that to a thickness of approximately 1 to 2 μm after curing, and then heated and dried at 120°C to remove the solvent, to prepare single-sided metal-clad laminate intermediate A'. The single-sided metal-clad laminate intermediate A' was subjected to stepwise heat treatment from 120°C to 360°C to complete the imidization and form an insulating resin layer, thereby preparing the single-sided metal-clad laminate intermediate A (insulating resin layer thickness: 10 μm, CTE: 21 ppm / K, storage modulus at 30°C: 7.6 GPa, Tg: 300°C).

[0164] (Production Example 2) <Preparation of Single-Sided Metal-Clad Laminate Intermediate B> Polyamic acid solution 2 was uniformly applied onto electrolytic copper foil (thickness: 12 μm, surface roughness Rzjis 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 that to a thickness of approximately 20 μm after curing, and then heated and dried at 120°C to remove the solvent. Polyamic acid solution 2 was further uniformly applied onto that to a thickness of approximately 2 to 3 μm after curing, and then heated and dried at 120°C to remove the solvent, to prepare single-sided metal-clad laminate intermediate B'. The single-sided metal-clad laminate intermediate B' was subjected to stepwise heat treatment from 120°C to 360°C to complete the imidization and form an insulating resin layer, thereby preparing the single-sided metal-clad laminate intermediate B (insulating resin layer thickness: 25 μm, CTE: 21 ppm / K, storage modulus at 30°C: 7.6 GPa, Tg: 300°C).

[0165] (Production Example 3) <Preparation of Single-Sided Metal-Clad Laminate Intermediate C> Polyamic acid solution 2 was uniformly applied onto electrolytic copper foil (thickness: 12 μm, surface roughness Rzjis on the resin layer side: 0.6 μm) to a thickness of approximately 3 to 5 μm after curing, and then heated and dried at 120°C to remove the solvent. Next, polyamic acid solution 1 was uniformly applied onto that to a thickness of approximately 32 μm after curing, and then heated and dried at 120°C to remove the solvent. Polyamic acid solution 2 was further uniformly applied onto that to a thickness of approximately 3 to 5 μm after curing, and then heated and dried at 120°C to remove the solvent, preparing single-sided metal-clad laminate intermediate C'. The single-sided metal-clad laminate intermediate C' was subjected to stepwise heat treatment from 120°C to 360°C to complete the imidization and form an insulating resin layer, thereby preparing the single-sided metal-clad laminate intermediate C (insulating resin layer thickness: 40 μm, CTE: 21 ppm / K, storage modulus at 30°C: 7.6 GPa, Tg: 300°C).

[0166] (Production Example 4) <Preparation of Single-Sided Metal-Clad Laminate Intermediate D> Polyamic acid solution 2 was uniformly applied onto electrolytic copper foil (thickness: 12 μm, surface roughness Rzjis on the resin layer side: 0.6 μm) to a thickness of approximately 3 to 5 μm after curing, and then heated and dried at 120°C to remove the solvent. Next, polyamic acid solution 1 was uniformly applied onto that to a thickness of approximately 42 μm after curing, and then heated and dried at 120°C to remove the solvent. Polyamic acid solution 2 was further uniformly applied onto that to a thickness of approximately 3 to 5 μm after curing, and then heated and dried at 120°C to remove the solvent, preparing single-sided metal-clad laminate intermediate D'. The single-sided metal-clad laminate intermediate D' was subjected to stepwise heat treatment from 120°C to 360°C to complete the imidization and form an insulating resin layer, thereby preparing a single-sided metal-clad laminate intermediate D (insulating resin layer thickness: 50 μm, CTE: 21 ppm / K, storage modulus at 30°C: 7.6 GPa, Tg: 300°C).

[0167] [Example 1] <Preparation of single-sided metal-clad laminate 1> The adhesive layer resin composition was uniformly applied to the insulating resin layer of single-sided metal-clad laminate intermediate C to a dry thickness of 60 μm. The temperature was raised from 80°C to 160°C for 6 minutes, followed by heat treatment for drying and crosslinking to form adhesive layer-attached metal-clad laminate 1. A 25 μm-thick polyimide film (manufactured by DuPont-Toray Co., Ltd., product name: Kapton 100V, CTE: 21 ppm / K, storage modulus at 30°C: 3.4 GPa) was placed on the adhesive layer surface of adhesive layer-attached metal-clad laminate 1 and temporarily pressed at 80°C, 0.5 MPa, for 2 seconds to prepare primary laminate 1. Primary laminate 1 was then heat-treated in a thermostatic chamber at 180°C for 120 hours to obtain single-sided metal-clad laminate 1 with an insulating resin layer thickness of 125 μm.

[0168] [Example 2] <Preparation of single-sided metal-clad laminate 2> The insulating resin layer side of single-sided metal-clad laminate intermediate D was placed facing the adhesive layer surface of adhesive layer-attached metal-clad laminate 1, and temporary pressure bonding was performed at 80°C, 0.5 MPa, and for 2 seconds to prepare primary laminate 2. Primary laminate 2 was heat-treated in a thermostatic chamber at 180°C for 120 hours to obtain double-sided metal-clad laminate 2. The copper foil on the side of single-sided metal-clad laminate intermediate D of this double-sided metal-clad laminate 2 was etched to obtain single-sided metal-clad laminate 2 with an insulating resin layer thickness of 150 μm.

[0169] [Example 3] <Preparation of single-sided metal-clad laminate 3> The adhesive layer resin composition was uniformly applied to the insulating resin layer of single-sided metal-clad laminate intermediate A to a dry thickness of 53 μm. The temperature was raised from 80°C to 160°C for 6 minutes, followed by heat treatment for drying and crosslinking to form adhesive layer-attached metal-clad laminate 3. A 12 μm-thick polyimide film (manufactured by DuPont-Toray Co., Ltd., product name: Kapton 50EN, CTE: 21 ppm / K, storage modulus at 30°C: 5.3 GPa, Tg: 300°C or higher) was placed on the adhesive layer surface of adhesive layer-attached metal-clad laminate 3 and temporarily pressed at 80°C, 0.5 MPa, for 2 seconds to prepare primary laminate 3. Primary laminate 3 was then heat-treated in a thermostatic chamber at 180°C for 120 hours to obtain single-sided metal-clad laminate 3 with an insulating resin layer thickness of 75 μm.

[0170] [Comparative Example 1] <Preparation of single-sided metal-clad laminate 4> The adhesive layer resin composition was uniformly applied to the insulating resin layer of single-sided metal-clad laminate intermediate B to a dried thickness of 63 μm. The temperature was raised from 80 ° C to 160 ° C for 6 minutes, followed by heat treatment for drying and crosslinking to form an adhesive layer-attached metal-clad laminate 4. A 12 μm-thick PET film (manufactured by Toray Industries, Inc., trade name: Lumirror #12-S10, CTE: 21 ppm / K, storage modulus at 30 ° C: 4.3 GPa, Tg: 110 ° C) was placed on the adhesive layer surface of the adhesive layer-attached metal-clad laminate 4 and temporarily pressure-bonded at 80 ° C, 0.5 MPa, for 2 seconds to prepare a primary laminate 4. The primary laminate 4 was then heat-treated at 180 ° C for 120 hours in a thermostatic chamber to obtain a single-sided metal-clad laminate 4 with an insulating resin layer thickness of 100 μm.

[0171] Comparative Example 2 <Preparation of Single-Sided Metal-Clad Laminate 5> A 12 μm thick PEN film (manufactured by Toyobo Co., Ltd., product name: Teonex Q51, CTE: 21 ppm / K, storage modulus at 30°C: 6.5 GPa, Tg: 155°C) was placed on the adhesive layer surface of the adhesive-layered metal-clad laminate 4 and temporarily pressed at 80°C, 0.5 MPa, for 2 seconds to prepare a primary laminate 5. The primary laminate 5 was heat-treated in a thermostatic oven at 180°C for 120 hours to obtain a single-sided metal-clad laminate 5 having an insulating resin layer thickness of 100 μm.

[0172] Comparative Example 3 <Preparation of Single-Sided Metal-Clad Laminate 6> The adhesive layer resin composition was uniformly applied to the insulating resin layer of single-sided metal-clad laminate intermediate B to a dried thickness of 25 μm. The temperature was raised from 80°C to 160°C for 6 minutes, followed by heat treatment for drying and crosslinking to form an adhesive layer-attached metal-clad laminate 6. The insulating resin layer side of single-sided metal-clad laminate intermediate D was placed facing the adhesive layer surface of adhesive layer-attached metal-clad laminate 6, and the resulting laminate was temporarily pressed at 80°C, 0.5 MPa, and pressure for 2 seconds to prepare primary laminate 6. Primary laminate 6 was then heat-treated in a thermostatic chamber at 180°C for 120 hours to obtain double-sided metal-clad laminate 6. The copper foil on the single-sided metal-clad laminate intermediate D side of double-sided metal-clad laminate 6 was etched to obtain a single-sided metal-clad laminate 6 with an insulating resin layer thickness of 100 μm.

[0173] Table 1 shows various parameters and evaluation results in the examples and comparative examples.

[0174] [Table 1]

[0175] 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]

[0176] 10...thermoplastic polyimide layer, 20...non-thermoplastic polyimide layer, 30...thermoplastic polyimide layer, 40...first insulating resin layer, 50A, 50B...second insulating resin layer, 60...thermoplastic polyimide layer, 70...non-thermoplastic polyimide layer, 80...thermoplastic polyimide layer, 100A, 100B...metal-clad laminate, 101A, 101B...resin laminate, 110...metal layer, 120...circuit board, 200...multilayer circuit board, 210...metal layer, 220...insulating resin layer, 230...wiring layer, AD...adhesive layer, BS...bonding sheet

Claims

1. a metal layer; a first insulating resin layer (A) consisting of a single layer or multiple layers laminated in contact with at least one surface of the metal layer; an adhesive layer laminated in contact with the first insulating resin layer (A); a second insulating resin layer (B) consisting of a single layer or multiple layers laminated in contact with the adhesive layer; Equipped with The first insulating resin layer (A) and the second insulating resin layer (B) both satisfy the following conditions (I) to (III): (I) Storage modulus at 30°C is 1.0 x 10 ９ Pa or more; (II) The average thermal expansion coefficient from 250°C to 100°C is within the range of 10 to 30 ppm / K; (III) a glass transition temperature (Tg) of 180°C or higher; While satisfying the above, the second insulating resin layer (B) is different from the first insulating resin layer (A) in at least one of thickness, number of constituent layers, material, storage modulus, and thermal expansion coefficient; The storage modulus of the second insulating resin layer (B) in the temperature range of 30° C. to 200° C. is 1.0×10 ９ Pa or more, The bending moment (M Ａ ) and the bending moment (M Ｂ ) absolute value of the difference (|M Ａ -M Ｂ A metal-clad laminate having a curl index represented by |) of less than 10 mNm.

2. The exposed surface of the second insulating resin layer (B) has a storage modulus of 1.0×10 in a temperature range of 30° C. to 200° C. ９ The metal-clad laminate according to claim 1, wherein the modulus is 100 Pa or more.

3. The second insulating resin layer (B) is subjected to the following steps (1) to (3): (1) The second insulating resin layer (B) of the metal-clad laminate and another copper foil are thermocompression bonded under conditions of 150°C, 3.0 MPa, and 45 minutes; (2) After heat-pressing, the specimen is cut into a piece 10 mm wide and 70 mm long to prepare a test piece; (3) The other copper foil is fixed, and the metal-clad laminate is pulled in a 180° direction at a speed of 50 mm / min. The median strength when 10 mm of the second insulating resin layer (B) is peeled from the other copper foil is determined as the peel strength; 2. The metal-clad laminate according to claim 1, wherein the peel strength measured by the method is less than 0.1 kN / m.

4. The thickness t of the first insulating resin layer (A) ２ The thickness t of the second insulating resin layer (B) ４ The ratio (t ４ / t ２ 2. The metal-clad laminate according to claim 1, wherein the value of (a) is in the range of 0.5 to 2.

0.

5. The adhesive layer satisfies the following conditions (i) to (iii): (i) a storage modulus at 50°C of 1800 MPa or less; (ii) the maximum storage modulus in the temperature range of 180°C to 260°C is 800 MPa or less; (iii) a glass transition temperature (Tg) of 180°C or less; 2. The metal-clad laminate according to claim 1, wherein the above formula (1) is satisfied.

6. the adhesive layer comprises an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue, 2. The metal-clad laminate according to claim 1, wherein the adhesive polyimide contains 50 or more molar parts of diamine residues 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, per 100 molar parts of the diamine residues.

7. a first circuit board having a wiring layer formed on an insulating resin layer; a bonding sheet laminated in contact with the wiring layer of the first circuit board; a single-sided metal-clad laminate laminated in contact with the surface of the bonding sheet opposite to the first circuit board; A multilayer circuit board comprising: A multilayer circuit board characterized in that the single-sided metal-clad laminate is a metal-clad laminate described in any one of claims 1 to 6, and the bonding sheet and the second insulating resin layer (B) are laminated in contact with each other.

8. An electronic device comprising the multilayer circuit board according to claim 7.

9. An electronic device comprising the multilayer circuit board according to claim 7.

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