Metal-clad laminate, circuit board, multilayer circuit board

Abstract

Provided is a metal-clad laminate, a circuit board, a multilayer circuit board, and a method for manufacturing the same. The multilayer circuit board has excellent dimensional stability of a conductor circuit and includes an adhesive layer that can reduce transmission loss even in transmission of a high-frequency signal. A circuit board (101) includes an insulating resin layer (10), a conductor circuit layer (50) laminated to one surface of the insulating resin layer (10), and an adhesive layer (30) laminated to the other surface of the insulating resin layer (10). A multilayer circuit board (200) is manufactured by overlapping the adhesive layer (30) of a first circuit board (101) with the conductor circuit layer (50) of a second circuit board (101) in a manner such that the adhesive layer (30) faces the conductor circuit layer (50), overlapping the adhesive layer (30) of the second circuit board (101) with the conductor circuit layer (50) of any circuit board (110) not having the adhesive layer (30) in a manner such that the adhesive layer (30) faces the conductor circuit layer (50), and pressure-bonding these together.

Description

TECHNICAL FIELD

[0001] The present application relates to a metal-clad laminate sheet, a circuit board, and a multilayer circuit board having conductor circuit layers laminated in multiple layers and a method for manufacturing the same. BACKGROUND

[0002] In recent years, with the progress of high-density and high-functionality of electronic machines, circuit board materials having further dimensional stability or excellent high-frequency characteristics are required. In particular, for the characteristics of the organic interlayer insulating material required for high-speed signal processing, it is important to be low-dielectric constant and low-dielectric loss. In order to cope with high frequency, a multilayer wiring board in which a liquid crystal polymer (LCP) characterized by low dielectric constant and low dielectric loss tangent is made into a dielectric layer is proposed (for example, Patent Literature 1). The multilayer wiring board in which the liquid crystal polymer is made into an insulating layer is manufactured by performing heat press bonding in a state of being heated to the vicinity of the melting point of the liquid crystal polymer substrate as a thermoplastic resin, and thus, positional displacement of the circuit conductor is easily caused by thermal deformation of the liquid crystal polymer substrate, and there is a concern that adverse effects on electrical characteristics such as impedance mismatching occur. In addition, the multilayer wiring board in which the liquid crystal polymer is made into a substrate layer does not exhibit an anchoring effect when the multilayer bonding interface is smooth, and the interlayer adhesion is insufficient, and thus, roughening treatment needs to be performed on the respective surfaces of the circuit conductor and the liquid crystal polymer substrate, and there is a problem point that the manufacturing process is complicated.

[0003] Furthermore, as a technology related to an adhesive layer in which a polyimide is a main component, a crosslinked polyimide resin obtained by reacting a polyimide using a diamine compound derived from an aliphatic diamine such as a dimer acid as a raw material with an amino compound having at least two primary amino groups as a functional group is applied to an adhesive layer of a coverlay film (for example, Patent Literature 2). The crosslinked polyimide resin of Patent Literature 2 has the following advantages: no volatile components containing a cyclic siloxane compound are generated, excellent solder heat resistance is obtained, and the adhesion of the wiring layer and the coverlay film is not reduced even in a use environment repeatedly exposed to high temperatures. However, the possibility of application in high-frequency signal transmission is not studied in Patent Literature 2.

[0004] [Patent Literature]

[0005] [Patent Literature]

[0006] [Patent Literature 1] Japanese Patent Laid-Open No. 2005-317953

[0007] [Patent Literature 2] Japanese Patent Laid-Open No. 2013-1730 SUMMARY

[0008] [Problems to be Solved by the Invention]

[0009] In the future, in a multilayer circuit board, as a directional property to achieve a high-frequency signal transmission, it is considered that the total thickness of the insulating resin layer or the adhesive layer is increased while maintaining the dimensional stability of the conductor circuit, thereby achieving improvement in dielectric properties. For this reason, in a metal-clad laminate or a circuit board that is a material of a multilayer circuit board, not only the material but also the structure of these requires a design idea different from that of the previous multilayer circuit board.

[0010] Therefore, an object of the present application is to provide a multilayer circuit board having a novel structure in which the dimensional stability of the conductor circuit is excellent and in which reduction in transmission loss can be achieved even in transmission of a high-frequency signal.

[0011] [Technical Means to Solve the Problems]

[0012] The present inventors made intensive studies, and as a result, found that by using a metal-clad laminate having a specific structure as a material of a multilayer circuit board, the dimensional stability of the conductor circuit can be maintained while maintaining excellent adhesiveness, and at the same time, high-frequency signal transmission can be achieved, thereby completing the present application.

[0013] That is, the metal-clad laminate of the present application includes: an insulating resin layer; a metal layer laminated to one surface of the insulating resin layer; and an adhesive layer laminated to the other surface of the insulating resin layer.

[0014] In addition, the circuit board of the present application includes: an insulating resin layer; a conductor circuit layer formed on one surface of the insulating resin layer; and an adhesive layer laminated to the other surface of the insulating resin layer.

[0015] Furthermore, in the metal-clad laminate or the circuit board of the present application, the resin constituting the adhesive layer is a thermoplastic resin or a thermosetting resin, and satisfies the following conditions (i) to (iii):

[0016] (i) the storage elastic modulus at 50°C is 1800 MPa or less;

[0017] (ii) the maximum value of the storage elastic modulus in a temperature range from 180°C to 260°C is 800 MPa or less;

[0018] (iii) the glass transition temperature (Tg) is 180°C or lower.

[0019] In the metal-clad laminate or the circuit board of the present application, the thermoplastic resin can be an adhesive polyimide containing tetracarboxylic acid residues and diamine residues. In this case, the adhesive polyimide can contain 50 mol or more of diamine residues derived from a dimer acid type diamine per 100 mol of the total amount of the diamine residues, the dimer acid type diamine being obtained by substituting both terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group.

[0020] The metal-clad laminate of the present application can be a material for a circuit board in which the metal layer is processed into a wiring.

[0021] In the metal-clad laminate or the circuit board of the present application, the adhesive polyimide can contain 90 mol or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by General Formula (1) and / or General Formula (2) in total per 100 mol of the total amount of the tetracarboxylic acid residues.

[0022] [Chemical Formula 1]

[0023]

[0024] In General Formula (1), X represents a single bond or a divalent group selected from the following formulae, and in General Formula (2), the cyclic moiety represented by Y represents a cyclic saturated hydrocarbon group selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring.

[0025] [Chemical Formula 2]

[0026] -CO-, -SO2-, -O-,

[0027] -C(CF3)2-,

[0028] -COO- or -COO-Z-OCO-

[0029] In the formula, Z represents -C6H4-, -(CH2)n-, or -CH2-CH(-O-C(=O)-CH3)-CH2-, and n represents an integer of 1 to 20.

[0030] In the metal-clad laminate or the circuit board of the present application, the adhesive polyimide can contain diamine residues derived from the dimer acid type diamine in an amount of 50 mol or more and 99 mol or less per 100 mol of the total amount of the diamine residues, and can contain diamine residues derived from at least one diamine compound selected from the group consisting of diamine compounds represented by General Formula (B1) to General Formula (B7) in an amount of 1 mol or more and 50 mol or less.

[0031] [Chemical Formula 3]

[0032]

[0033] In formula (B1) to formula (B7), R1 independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, the linking group A independently represents 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; wherein, the portion common to formula (B2) is removed from formula (B3), and the portion common to formula (B4) is removed from formula (B5).

[0034] The multilayer circuit board of the present application is obtained by laminating a plurality of the circuit boards, and includes at least one or more of the above-described circuit board as the circuit board.

[0035] The manufacturing method of the multilayer circuit board of the first aspect of the present application can include:

[0036] a step of preparing a plurality of circuit boards including an insulating resin layer, a conductor circuit layer formed on one surface of the insulating resin layer, and an adhesive layer laminated on the other surface of the insulating resin layer; and

[0037] a step of overlapping and pressure bonding the conductor circuit layer of one of the circuit boards and the adhesive layer of the other of the circuit boards in a facing manner.

[0038] The manufacturing method of the multilayer circuit board of the second aspect of the present application can include:

[0039] a step of preparing a plurality of circuit boards including an insulating resin layer, a conductor circuit layer formed on one surface of the insulating resin layer, and an adhesive layer laminated on the other surface of the insulating resin layer; and

[0040] a step of overlapping and pressure bonding the adhesive layer of one of the circuit boards and the adhesive layer of the other of the circuit boards in a facing manner.

[0041] [Effects of the Invention]

[0042] The metal-clad laminate of the present application is a structure having a metal layer on one surface of an insulating resin layer and an adhesive layer on the other surface of the insulating resin layer, and thus, a multilayer circuit board can be easily manufactured by lamination, and is useful as a material for a multilayer circuit board. In addition, in the case where a multilayer circuit board is manufactured using the metal-clad laminate, the size stability of the conductor circuit can be maintained while ensuring the covering property and adhesion to the conductor circuit layer, and further ensuring the thickness of the entire resin layer. Therefore, a multilayer circuit board having good interlayer connection and high reliability can be obtained by using the metal-clad laminate of the present application.

[0043] In addition, the multilayer circuit substrate of the present application can reduce transmission loss even in transmission of high frequency signals, and can realize high-density integration or high-density mounting of electronic parts. In addition, the multilayer circuit substrate of the present application is also excellent in heat resistance, and thus can mount a semiconductor chip having a large amount of heat generation. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a cross-sectional view showing the structure of a metal-clad laminate according to an embodiment of the present application.

[0045] Figure 2 is a cross-sectional view showing the structure of a circuit substrate according to an embodiment of the present application.

[0046] Figure 3 is a cross-sectional view showing the structure of a multilayer circuit substrate according to a first embodiment of the present application.

[0047] Figure 4 is an explanatory view showing a manufacturing process of the multilayer circuit substrate according to the first embodiment of the present application.

[0048] Figure 5 is a cross-sectional view showing the structure of a multilayer circuit substrate according to a second embodiment of the present application.

[0049] Figure 6 is an explanatory view showing a manufacturing process of the multilayer circuit substrate according to the second embodiment of the present application.

[0050] [Explanation of Symbols]

[0051] 10: Insulating resin layer

[0052] 20: Metal layer

[0053] 30: Adhesive layer

[0054] 40: Single-sided metal-clad laminate

[0055] 50: Conductor circuit layer

[0056] 100: Metal-clad laminate

[0057] 101: Circuit substrate

[0058] 102: Circuit substrate unit

[0059] 110: Arbitrary circuit substrate

[0060] 200, 201: Multilayer circuit substrate

[0061] T1: Total thickness

[0062] T2, T3: Thickness DETAILED DESCRIPTION

[0063] Embodiments of the present application are described in detail.

[0064] [metal-clad laminate]

[0065] Figure 1 is a cross-sectional view showing the structure of a metal-clad laminate according to an embodiment of the present application. The metal-clad laminate 100 according to the present embodiment includes an insulating resin layer 10, a metal layer 20 laminated to one surface of the insulating resin layer 10, and an adhesive layer 30 laminated to the other surface of the insulating resin layer 10. That is, the metal-clad laminate 100 has a structure in which the metal layer 20 / insulating resin layer 10 / adhesive layer 30 are sequentially laminated. If another expression is used, the metal-clad laminate 100 has a structure in which the adhesive layer 30 is further added to the back surface side (insulating resin layer 10 side) of a single-sided metal-clad laminate 40 in which the insulating resin layer 10 and the metal layer 20 are laminated. Further, the adhesive layer 30 can be formed on the entire surface of the one surface of the insulating resin layer 10 or can be formed only on a part thereof.

[0066] [metal-clad laminate]

[0067] The single-sided metal-clad laminate 40 is not particularly limited in its constitution and a generally used material as a flexible printed circuit (FPC) material can be used. For example, a commercially available copper-clad laminate such as R-F705T (trade name) manufactured by Panasonic Corporation, Espanex (trade name) manufactured by JFE Chemicals & Materials Corporation, or the like can be used.

[0068] (metal layer)

[0069] The material of the metal layer 20 is not particularly limited and, for example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys of these can be exemplified. Among these, copper or a copper alloy is particularly preferable. Further, the material of the wiring layer in the circuit substrate according to the present embodiment described later is the same as the material of the metal layer 20.

[0070] The thickness of the metal layer 20 is not particularly limited and, for example, in the case where a metal foil such as a copper foil is used, it is preferably 35 μm or less, more preferably in the range of 5 μm to 25 μm. From the viewpoint of production stability and handling properties, the lower limit value of the thickness of the metal layer is preferably set to 5 μm. Further, in the case where a copper foil is used, it can be a rolled copper foil or an electrolytic copper foil. In addition, a commercially available copper foil can be used as the copper foil.

[0071] In addition, the metal foil can also be subjected to rust-preventive treatment or surface treatment for the purpose of improving adhesion using, for example, siding, aluminum alcoholates, aluminum chelates, silane coupling agents, and the like.

[0072] (insulating resin layer)

[0073] As the insulating resin layer 10, there is no particular limitation if a resin having electrical insulation is included, and examples that can be given include polyimide, liquid crystal polymer, epoxy resin, phenol resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, ethylene tetrafluoroethylene (ETFE), bismaleimide triazine (BT) resin, and the like, with polyimide being preferred. Furthermore, in the present application, the term "polyimide" refers not only to polyimide, but also to polymers having an imide group in the molecular structure, such as polyamide-imide, polyether-imide, polyester-imide, polysiloxane-imide, and polybenzimidazole-imide.

[0074] In addition, the insulating resin layer 10 is not limited to a single layer, and can have a plurality of resin layers laminated. In addition, the insulating resin layer 10 preferably includes a non-thermoplastic polyimide layer formed of a non-thermoplastic polyimide. Furthermore, the "non-thermoplastic polyimide" is generally a polyimide that does not exhibit adhesion even when softened by heating, and in the present application, refers to a polyimide having a storage elastic modulus of 1.0 x 10 9 Pa or more and a storage elastic modulus of 3.0 x 10 8 Pa or more at 300°C.

[0075] The insulating resin layer 10 can be selected and used from among commercially available polyimide films, commercially available liquid crystal polymer films, or resins used as insulating substrates in commercially available metal-clad laminated boards, for example. As the polyimide film, Upilex (trade name) manufactured by Ube Industries, Ltd., Kapton (trade name) manufactured by Toray Dupont, Inc., Apical (trade name) manufactured by Kaneka Corporation, and Pixeo (trade name) manufactured by Kaneka Corporation can be used, and as the liquid crystal polymer film, Vecstar (trade name) manufactured by Kuraray Co., Ltd., BIAC Film (trade name) manufactured by Primatech Corporation, and the like can be used.

[0076] The coefficient of thermal expansion (CTE) of the insulating resin layer 10 is not particularly limited, and can be in a range of 10 ppm / K or more, preferably in a range of 10 ppm / K or more and 30 ppm / K or less, and more preferably in a range of 15 ppm / K or more and 25 ppm / K or less. If the CTE is less than 10 ppm / K or exceeds 30 ppm / K, warping or a decrease in dimensional stability occurs. The CTE can be controlled to be desired by appropriately changing the combination, thickness, drying / hardening conditions of the raw materials used.

[0077] Further, the coefficient of thermal expansion (CTE) of the entire resin layer including the insulating resin layer 10 and the adhesive layer 30 is not particularly limited, and is preferably in a range of 10 ppm / K or more and 30 ppm / K or less, and more preferably in a range of 15 ppm / K or more and 25 ppm / K or less. If the CTE of the entire resin layer is less than 10 ppm / K or exceeds 30 ppm / K, warping or a decrease in dimensional stability occurs.

[0078] The insulating resin layer 10, for example, in the case of being applied to a multilayer circuit substrate, in order to suppress deterioration of dielectric loss, the tangent of dielectric loss (Tan δ) at 10 GHz can be preferably 0.02 or less, more preferably in a range of 0.0005 or more and 0.01 or less, and further preferably in a range of 0.001 or more and 0.008 or less. If the tangent of dielectric loss at 10 GHz of the insulating resin layer 10 exceeds 0.02, when applied to a multilayer circuit substrate, an adverse situation such as a loss of an electric signal on a transmission path of a high frequency signal is easily caused. On the other hand, the lower limit value of the tangent of dielectric loss at 10 GHz of the insulating resin layer 10 is not particularly limited, and can be considered as a physical property control of the insulating resin layer of the multilayer circuit substrate.

[0079] The insulating resin layer 10, for example, in the case of being applied as an insulating resin layer of a multilayer circuit substrate, in order to ensure impedance matching, the dielectric constant (ε) at 10 GHz is preferably 4.0 or less. If the dielectric constant at 10 GHz of the insulating resin layer 10 exceeds 4.0, when applied to a multilayer circuit substrate, deterioration of dielectric loss of the insulating resin layer 10 is caused, and an adverse situation such as a loss of an electric signal on a transmission path of a high frequency signal is easily caused.

[0080] <Adhesive Layer>

[0081] The adhesive layer 30 contains a thermoplastic resin or a thermosetting resin, and satisfies the following conditions:

[0082] (i) the storage elastic modulus at 50°C is 1800 MPa or less;

[0083] (ii) the maximum value of the storage elastic modulus in the temperature range from 180°C to 260°C is 800 MPa or less; and

[0084] (iii) the glass transition temperature (Tg) is 180°C or less.

[0085] As such a resin, for example, polyimide resin, polyamide resin, epoxy resin, phenoxy resin, acrylic resin, polyurethane resin, styrene resin, polyester resin, phenol resin, polysulfone resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene resin, polypropylene resin, silicone resin, polyether ketone resin, polyvinyl alcohol resin, polyvinyl butyral resin, styrene-maleimide copolymer, maleimide-vinyl compound copolymer, or (meth) acrylic copolymer, benzoxazine resin, bismaleimide resin, and cyanate ester resin, etc. can be cited, and a resin satisfying conditions (i) to (iii) can be selected from among these, or a resin designed so as to satisfy conditions (i) to (iii) can be used in the adhesive layer 30.

[0086] In the case where the adhesive layer 30 is a thermosetting resin, an organic peroxide, a hardener, a hardening accelerator, etc. can be contained, and a hardener and a hardening accelerator, or a catalyst and a cocatalyst can be used in combination as necessary. The addition amount and the presence or absence of addition of the hardener, the hardening accelerator, the catalyst, the cocatalyst, and the organic peroxide can be determined as long as the conditions (i) to (iii) can be ensured.

[0087] The adhesive layer 30 has a storage elastic modulus at 50°C of 1800 MPa or less and a maximum value of the storage elastic modulus in the temperature range from 180°C to 260°C of 800 MPa or less as indicated in conditions (i) and (ii). It is considered that such a characteristic of the adhesive layer 30 is a main reason for relaxing internal stress at the time of heat pressing and maintaining dimensional stability after circuit processing. In addition, the storage elastic modulus at the upper limit temperature (260°C) of the temperature range of the adhesive layer 30 is preferably 800 MPa or less, more preferably in the range of 500 MPa or less. By setting such a storage elastic modulus, even after a solder reflow process after circuit processing, warping is less likely to occur.

[0088] The adhesive layer 30 has a glass transition temperature (Tg) in the range of 180°C or less, preferably 160°C or less as indicated in condition (iii). By setting the glass transition temperature of the adhesive layer 30 to 180°C or less, heat pressing at low temperature can be performed, and thus, internal stress generated at the time of lamination can be relaxed, and dimensional change can be suppressed. If the Tg of the adhesive layer 30 exceeds 180°C, the temperature at the time of adhesion with an insulating resin layer 10 and an arbitrary circuit substrate interposed therebetween becomes high, and there is a concern that dimensional stability can be impaired.

[0089] (CTE of the adhesive layer)

[0090] The thermoplastic resin or the thermosetting resin constituting the adhesive layer 30 is high in thermal expansion, but is low in elasticity and has a low glass transition temperature, and thus, even if the CTE exceeds 30 ppm / K, internal stress generated at the time of lamination can be mitigated. Therefore, the CTE of the adhesive layer 30 is preferably 35 ppm / K or more, more preferably in a range of 35 ppm / K or more and 200 ppm / K or less, and further preferably in a range of 35 ppm / K or more and 150 ppm / K or less. By appropriately changing the combination, thickness, drying / hardening conditions of the raw materials used, the adhesive layer 30 having a desired CTE can be produced.

[0091] (Tangent of dielectric loss of the adhesive layer)

[0092] In the case where the adhesive layer 30 is applied to a multilayer circuit substrate, for example, in order to suppress deterioration of dielectric loss, the tangent of dielectric loss (Tan δ) at 10 GHz can be preferably 0.004 or less, more preferably 0.003 or less, and further preferably 0.002 or less. If the tangent of dielectric loss of the adhesive layer 30 at 10 GHz exceeds 0.004, when applied to a multilayer circuit substrate, an adverse situation such as loss of an electric signal on a transmission path of a high-frequency signal is easily caused. On the other hand, the lower limit value of the tangent of dielectric loss of the adhesive layer 30 at 10 GHz is not particularly limited.

[0093] (Dielectric constant of the adhesive layer)

[0094] In the case where the adhesive layer 30 is applied to a multilayer circuit substrate, for example, in order to ensure impedance matching, the dielectric constant at 10 GHz is preferably 4.0 or less. If the dielectric constant of the adhesive layer 30 at 10 GHz exceeds 4.0, when applied to a multilayer circuit substrate, an adverse situation such as loss of an electric signal on a transmission path of a high-frequency signal is easily caused due to deterioration of dielectric loss of the adhesive layer 30.

[0095] (Filler)

[0096] The adhesive layer 30 can contain a filler as needed. As the filler, for example, silica, alumina, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, metal salts of organic phosphinic acid, and the like can be exemplified. These can be used alone or in combination of two or more.

[0097] (Adhesive polyimide)

[0098] Next, a specific example of the adhesive layer 30 will be described, taking the case where the resin constituting the adhesive layer 30 is an adhesive thermoplastic polyimide containing tetracarboxylic acid residues and diamine residues (hereinafter, sometimes referred to as "adhesive polyimide") as an example. The adhesive polyimide is manufactured by imidizing a polyamic acid obtained by reacting a specific anhydride with a diamine compound, and therefore, the specific example of the adhesive polyimide will be understood by describing the anhydride and the diamine compound. Further, in the present application, the term "tetracarboxylic acid residues" refers to tetravalent groups derived from tetracarboxylic dianhydrides, and the term "diamine residues" refers to divalent groups derived from diamine compounds. In addition, the term "thermoplastic polyimide" generally refers to polyimides in which a glass transition temperature (Tg) can be clearly confirmed, and in the present application, refers to polyimides in which the storage elastic modulus at 30°C is 1.0 x 10 8 Pa or more and the storage elastic modulus at 300°C is less than 3.0 x 10 7 Pa.

[0099] (tetracarboxylic acid residues)

[0100] The adhesive polyimide preferably contains, in 100 mol of all tetracarboxylic acid residues, 90 mol or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by General Formula (1) and / or General Formula (2) (hereinafter, sometimes referred to as "tetracarboxylic acid residues (1)", "tetracarboxylic acid residues (2)"). In the present application, by containing, in 100 mol of all tetracarboxylic acid residues, 90 mol or more of the tetracarboxylic acid residues (1) and / or the tetracarboxylic acid residues (2), solvent solubility is imparted to the adhesive polyimide, and coexistence of flexibility and heat resistance of the adhesive polyimide is easily achieved, and therefore, is more preferable. If the total of the tetracarboxylic acid residues (1) and / or the tetracarboxylic acid residues (2) is less than 90 mol, there is a tendency that solvent solubility of the adhesive polyimide decreases.

[0101] [Chemical Formula 4]

[0102]

[0103] In General Formula (1), X represents a single bond, or a divalent group selected from the following formulae, and in General Formula (2), the cyclic moiety represented by Y represents a cyclic saturated hydrocarbon group selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring.

[0104] [Chemical Formula 5]

[0105] -CO-, -SO2-, -O-,

[0106] -C(CF3)2-,

[0107] -COO- or -COO-Z-OCO-

[0108] In the formula, Z represents -C6H4-, -(CH2)n- or -CH2-CH(-O-C(=O)-CH3)-CH2-, and n represents an integer of 1 to 20.

[0109] As the tetracarboxylic dianhydride to derive the tetracarboxylic acid residue (1), for example, 3,3',4,4'-diphenyltetracarboxylic 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-phenylene bis(trimellitic monoester anhydride) (TAHQ), ethylene glycol bis(trimellitic anhydride) ester (TMEG), and the like can be exemplified.

[0110] In addition, as the tetracarboxylic dianhydride to derive the tetracarboxylic acid residue (2), for example, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,4,5-cycloheptane tetracarboxylic dianhydride, 1,2,5,6-cyclooctane tetracarboxylic dianhydride, and the like can be exemplified.

[0111] The adhesive polyimide can contain a tetracarboxylic acid residue derived from an anhydride other than the tetracarboxylic anhydride represented by the general formula (1) or the general formula (2) within a range not impairing the effects of the invention.

[0112] (diamine residue)

[0113] The adhesive polyimide contains the dimer acid type diamine residue derived from the dimer acid type diamine in a range of 50 mol or more, for example, 50 mol or more and 99 mol or less, relative to 100 mol of all diamine residues, preferably in a range of 80 mol or more, for example, 80 mol or more and 99 mol or less. By containing the dimer acid type diamine residue in the amount, the dielectric properties of the adhesive layer 30 can be improved, and the heat press bonding properties can be improved by the lowering of the glass transition temperature of the adhesive layer 30 and the internal stress can be alleviated by the lowering of the elastic modulus. In addition, by providing the dimer acid type diamine residue in 50 mol or more, solvent solubility and thermoplasticity can be imparted, the water absorption of the adhesive layer 30 is reduced, and, for example, the dimensional change due to etching is reduced. If the dimer acid type diamine residue is less than 50 mol relative to 100 mol of all diamine residues, the solvent solubility of the adhesive polyimide is reduced.

[0114] Here, the so-called dimer acid type diamine refers to a diamine in which both terminal carboxylic acid groups (-COOH) of a dimer acid are substituted with a primary aminomethyl group (-CH2-NH2) or an amino group (-NH2). The dimer acid is a known dibasic acid obtained by an intermolecular polymerization reaction of an unsaturated fatty acid, and its industrial production process has been roughly standardized in the industry, and can be obtained by using a clay catalyst or the like to dimerize an unsaturated fatty acid having a carbon number of 11 to 22. The dimer acid obtained industrially is mainly composed of a dibasic acid having a carbon number of 36 obtained by dimerizing an unsaturated fatty acid having a carbon number of 18 such as oleic acid or linoleic acid, and contains a monomeric acid (carbon number 18), a trimeric acid (carbon number 54), and other polymerized fatty acids having a carbon number of 20 to 54 in an arbitrary amount depending on the degree of refinement. In the present application, the dimer acid is preferably a compound in which the dimer acid content is increased to 90% by weight or more by molecular distillation. In addition, a double bond remains after the dimerization reaction, but in the present application, a compound in which the unsaturation degree is reduced by further hydrogenation is also included in the dimer acid.

[0115] As a feature of the dimer acid type diamine, the polyimide can be given a property derived from the skeleton of the dimer acid. That is, the dimer acid type diamine is an aliphatic fatty acid having a large molecule with a molecular weight of about 560 to 620, and thus the molar volume of the molecule can be increased and the polar group of the polyimide can be relatively reduced. It is considered that such a feature of the dimer acid type diamine contributes to the suppression of the reduction of the heat resistance of the polyimide and the reduction of the dielectric constant and the dielectric loss tangent to improve the dielectric properties. In addition, since it contains two hydrophobic chains having a carbon number of 7 to 9 that move freely and two chain-like aliphatic amino groups having a length close to that of a carbon number of 18, the polyimide is not only given flexibility, but also can be provided with an asymmetric chemical structure or a non-planar chemical structure, and thus it is considered that the low dielectric constant and the low dielectric loss tangent of the polyimide can be achieved.

[0116] The dimer acid type diamine can be obtained as a commercial product, and for example, PRIAMINE 1073 (trade name) manufactured by CRODA Japan, PRIAMINE 1074 (trade name) manufactured by CRODA Japan, PRIAMINE 1075 (trade name) manufactured by CRODA Japan, Versamine 551 (trade name) manufactured by BASF Japan, Versamine 552 (trade name) manufactured by BASF Japan, and the like can be listed.

[0117] Further, the adhesive polyimide preferably contains, in a range of 1 mol% or more and 50 mol% or less in total, diamine residues derived from at least one diamine compound selected from the group consisting of diamine compounds represented by General Formula (B1) to General Formula (B7) below, more preferably in a range of 1 mol% or more and 20 mol% or less in total. The diamine compounds represented by General Formula (B1) to General Formula (B7) have a molecular structure having a curvature, and thus, by using at least one diamine compound selected from these in the above range, the softness of the polyimide molecular chain can be improved to impart solvent solubility and thermoplasticity. Further, by using the diamine compounds represented by General Formula (B1) to General Formula (B7), for example, even in the case where a via hole (through hole) is formed in the adhesive layer 30 by laser processing, the proportion of aromatic rings in the polyimide molecular structure becomes high, and thus, for example, the absorbance in the ultraviolet region can be improved, and in addition to this, the glass transition temperature of the adhesive layer 30 can be improved, and thus, the heat resistance to the temperature rise of the bottom metal due to laser light irradiation can be improved, and thus, the laser processability can be further improved. If the total amount of diamine residues derived from at least one diamine compound selected from the group consisting of diamine compounds represented by General Formula (B1) to General Formula (B7) exceeds 50 mol% with respect to 100 mol% of all diamine residues, the softness of the adhesive polyimide is insufficient, and in addition to this, the glass transition temperature is increased, and thus, the residual stress due to heat press bonding is increased, and there is a tendency that the post-etch dimensional change rate deteriorates.

[0118] [Chemical Formula 6]

[0119]

[0120] In General Formulae (B1) to (B7), R1independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, the linking group A independently represents a divalent group selected from -0-, -S-, -CO-, -SO-, -S02-, -COO-, -CH2-, -C(CH3)2-, -NH-, or -CONH-, and n1independently represents an integer of 0 to 4. Here, the portion common to General Formula (B2) is removed from General Formula (B3), and the portion common to General Formula (B4) is removed from General Formula (B5).

[0121] Further, the term "independently" means that the plurality of linking groups A, the plurality of R1, or the plurality of n1may be the same or different in one of General Formulae (B1) to (B7), or two or more thereof. In General Formulae (B1) to (B7), the hydrogen atoms in the two terminal amino groups can be substituted, for example, can be -NR2R3(where R2and R3independently represent an arbitrary substituent such as an alkyl group).

[0122] The diamine represented by formula (B1) (hereinafter, sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. It is considered that the diamine (B1) has an increased degree of freedom of the polyimide molecular chain and has a high flexibility by locating the amino group directly bonded to at least one benzene ring and the divalent linking group A in the meta position, thereby contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B1), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -0-, -CH2-, -C(CH3)2-, -CO-, -SO2-, -S-, -COO- are preferable.

[0123] As the diamine (B1), for example, 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, (3,3'-diamino)diphenylamine, and the like can be exemplified.

[0124] The diamine represented by formula (B2) (hereinafter, sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. It is considered that the diamine (B2) has an increased degree of freedom of the polyimide molecular chain and has a high flexibility by locating the amino group directly bonded to at least one benzene ring and the divalent linking group A in the meta position, thereby contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B2), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -0- is preferable.

[0125] As the diamine (B2), for example, 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]aniline, 3-[3-(4-aminophenoxy)phenoxy]aniline, and the like can be exemplified.

[0126] The diamine represented by formula (B3) (hereinafter, sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. It is considered that the diamine (B3) has an increased degree of freedom of the polyimide molecular chain and has a high flexibility by locating the two divalent linking groups A directly bonded to one benzene ring in the meta position to each other, thereby contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B3), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -0- is preferable.

[0127] As the diamine (B3), for example, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bis(oxy)]dianiline, 4,4'-[4-methyl-(1,3-phenylene)bis(oxy)]dianiline, 4,4'-[5-methyl-(1,3-phenylene)bis(oxy)]dianiline, and the like can be exemplified.

[0128] The diamine represented by formula (B4) (hereinafter, sometimes referred to as "diamine (B4)") is an aromatic diamine having four phenyl groups. It is considered that the diamine (B4) has a high flexibility by directly bonding the amino groups to at least one of the phenyl groups and by locating the divalent linking group A in the meta position, thereby contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B4), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -0-, -CH2-, -C(CH3)2-, -SO2-, -CO-, -CONH- are preferable.

[0129] As the diamine (B4), 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, bis[4,4'-(3-aminophenoxy)]benzamide, and the like can be exemplified.

[0130] The diamine represented by formula (B5) (hereinafter, sometimes referred to as "diamine (B5)") is an aromatic diamine having four phenyl groups. It is considered that the diamine (B5) has a high flexibility by directly bonding two divalent linking groups A to at least one of the phenyl groups and by locating the divalent linking groups A in the meta position to each other, thereby increasing the degree of freedom of the polyimide molecular chain and having a high flexibility, thereby contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B5), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -0- is preferable.

[0131] As the diamine (B5), 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]dianiline, and the like can be exemplified.

[0132] The diamine represented by formula (B6) (hereinafter, sometimes referred to as "diamine (B6)") is an aromatic diamine having four phenyl groups. It is considered that the diamine (B6) has a high flexibility by having at least two ether bonds, thereby contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B6), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -C(CH3)2-, -0-, -SO2-, -CO- are preferable.

[0133] As the diamine (B6), for example, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl] ether (BAPE), bis[4-(4-aminophenoxy)phenyl] sulfone (BAPS), bis[4-(4-aminophenoxy)phenyl] ketone (BAPK), and the like can be exemplified.

[0134] The diamine represented by the formula (B7) (hereinafter, sometimes referred to as "diamine (B7)") is an aromatic diamine having four phenyl groups. It is considered that the diamine (B7) has a divalent linking group A having high flexibility on both sides of the diphenyl skeleton, and thus contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B7), the thermoplasticity of the polyimide is improved. Here, as the linking group A, -0- is preferable.

[0135] As the diamine (B7), for example, bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl, and the like can be exemplified.

[0136] The adhesive polyimide can contain a diamine residue derived from a diamine compound other than the dimer acid type diamine and the diamines (B1) to (B7) within a range not impairing the effects of the invention.

[0137] Further, with respect to the adhesive polyimide, by selecting the kind of the tetracarboxylic acid residue and the diamine residue, or the respective molar ratios when two or more kinds of tetracarboxylic acid residues or diamine residues are contained, the coefficient of thermal expansion, the tensile elastic modulus, the glass transition temperature, and the like can be controlled. Further, in the case where a plurality of polyimide structural units are present, they can exist in a block form, or can exist randomly, and it is preferable that they exist randomly.

[0138] The imide group concentration of the adhesive polyimide is preferably 20% by weight or less. Here, the "imide group concentration" is a value obtained by dividing the molecular weight of the imide group portion (-(CO)2-N-) in the polyimide by the molecular weight of the entire structure of the polyimide. If the imide group concentration exceeds 20% by weight, the molecular weight of the resin itself becomes small, and the low moisture absorption property is also deteriorated due to the increase in the polar group, and the elastic modulus rises.

[0139] The weight average molecular weight of the adhesive polyimide is preferably, for example, in the range of 10,000 to 400,000, and 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 30 is reduced, and there is a tendency to be easily brittle. On the other hand, if the weight average molecular weight exceeds 400,000, the viscosity excessively increases, and there is a tendency to easily cause unevenness in the thickness of the adhesive layer 30, streaks, and the like in the coating work.

[0140] The adhesive polyimide, in the case of forming a multilayer circuit substrate, coats the conductor circuit layer of an arbitrary circuit substrate, and therefore, is most preferably a fully imidized structure in order to suppress the diffusion of copper. Among them, a part of the polyimide can be an amic acid. As for the imidization rate thereof, the infrared absorption spectrum of a polyimide film can be measured by using a Fourier transform infrared spectrophotometer (commercially available product: FT / IR 620 manufactured by Japan Spectroscopic Co., Ltd.) and utilizing a 1st reflection ATR (Attenuated Total Reflectance) method, and the imidization rate can be calculated based on the absorbance of the benzene ring absorber near 1015 cm -1 and the absorbance of the C=0 stretch derived from the imide group at 1780 cm -1 .

[0141] (crosslinking formation)

[0142] In the case where the adhesive polyimide has a ketone group, the ketone group is 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, whereby a crosslinking structure can be formed. By forming a crosslinking structure, the heat resistance of the adhesive polyimide can be improved. Tetra carboxylic anhydrides preferred for forming a polyimide having a ketone group can be exemplified by 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), for example, and diamine compounds preferred can be exemplified by 4,4'-bis(3-aminophenoxy)benzophenone (BABP), 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB), and the like aromatic diamines.

[0143] As the amino compound usable in the crosslinking formation of the adhesive polyimide, dihydrazide compounds, aromatic diamines, aliphatic amines, and the like can be exemplified. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds easily form a crosslinking structure even at room temperature, and there are concerns about the storage stability of the varnish, on the other hand, aromatic diamines need to be set to a high temperature in order to form a crosslinking structure. In the case of using dihydrazide compounds, the storage stability of the varnish and the shortening of the hardening time can coexist. As dihydrazide compounds, dihydrazide compounds such as 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, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthalene carboxylic acid dihydrazide, 4,4-bisbenzoyl dihydrazide, 1,4-naphthalene carboxylic acid dihydrazide, 2,6-pyridine diacid dihydrazide, itaconic acid dihydrazide, and the like can be exemplified. The above dihydrazide compounds can be used alone, or two or more kinds thereof can be used in combination.

[0144] The adhesive polyimide can be produced by reacting the tetracarboxylic dianhydride and the diamine compound in a solvent to form a polyamic acid, and then heating to close the ring. For example, the tetracarboxylic dianhydride and the diamine compound are dissolved in an organic solvent in approximately equimolar amounts, and the polymerization reaction is performed by stirring at a temperature in the range of 0°C to 100°C for 30 minutes to 24 hours, whereby a polyamic acid, which is a precursor of the adhesive polyimide, is obtained. During the reaction, the reaction components are dissolved in the range of 5% to 50% by weight, and preferably in the range of 10% to 40% by weight, of the generated precursor in the organic solvent. As the organic solvent used in the polymerization reaction, for example, 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, cresol, and the like can be exemplified. Two or more of these solvents can also be used in combination, and further, an aromatic hydrocarbon such as xylene or toluene can also be used in combination. The amount of the organic solvent used is not particularly limited, and it is preferably used in an amount adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5% to 50% by weight.

[0145] The polyamic acid synthesized is generally advantageously used as a reaction solvent solution, and can be concentrated, diluted, or replaced with another organic solvent as needed. In addition, the polyamic acid is generally advantageously used because of its excellent solvent solubility. The viscosity of the solution of the polyamic acid is preferably in the range of 500 cps to 100,000 cps. If it deviates from the range, thickness unevenness, streaks, or the like are easily generated in the film during the coating work using a coater or the like.

[0146] The method of imidizing the polyamic acid to form the polyimide is not particularly limited, and for example, heat treatment at a temperature in the range of 80°C to 400°C for 1 hour to 24 hours in the solvent can be appropriately used.

[0147] In the case where the adhesive polyimide obtained as above is subjected to cross-linking formation, the amino compound is added to the resin solution containing the polyimide having a ketone group, and a primary amino group of the amino compound is subjected to condensation reaction with the ketone group in the adhesive polyimide. By the condensation reaction, the resin solution is hardened to become a hardened product. In this case, the amount of the amino compound to be added can be such that the total of the primary amino groups can be 0.004 mole to 1.5 mole, preferably 0.005 mole to 1.2 mole, more preferably 0.03 mole to 0.9 mole, and most preferably 0.04 mole to 0.5 mole, per 1 mole of the ketone groups. In the case where the total of the primary amino groups is less than 0.004 mole per 1 mole of the ketone groups, the cross-linking of the polyimide chain with the amino compound is insufficient, and thus there is a tendency that the heat resistance of the adhesive layer 30 after hardening is not exhibited. If the amount of the amino compound to be added exceeds 1.5 mole, the unreacted amino compound functions as a thermoplastic agent, and there is a tendency that the heat resistance of the adhesive layer 30 is reduced.

[0148] The conditions for the condensation reaction for cross-linking formation are not particularly limited, provided that the primary amino group of the amino compound reacts with the ketone group in the adhesive polyimide to form an imine bond (C=N bond). The temperature for the heat condensation is preferably in the range of, for example, 120°C to 220°C, and more preferably in the range of 140°C to 200°C, for the purpose of, for example, releasing water generated by the condensation to the outside of the system, or simplifying the condensation process in the case where the heat condensation reaction is performed after 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 confirmed, for example, by measuring the infrared absorption spectrum using a Fourier transform infrared spectrophotometer (commercially available product: FT / IR 620 manufactured by Japan Spectroscopic Co., Ltd.), and confirming that the absorption peak derived from the ketone group in the polyimide resin near 1670 cm -1 disappears, and an absorption peak derived from the imine group appears near 1635 cm -1

[0149] The heat condensation of the primary amino group of the amino compound with the ketone group in the adhesive polyimide can be performed, for example, by (a) a method in which the amino compound is added immediately after the synthesis (imidization) of the adhesive polyimide and is subjected to heat; (b) a method in which an excess amount of the amino compound is previously added as a diamine component, and the residual amino compound which does not participate in the imidization or amidization is subjected to heat together with the adhesive polyimide immediately after the synthesis (imidization) of the adhesive polyimide; or (c) a method in which a composition of the adhesive polyimide to which the amino compound is added is processed into a predetermined shape (for example, after coating on an arbitrary substrate or after being formed into a film), and is subjected to heat. ​

[0150] In order to impart heat resistance to the adhesive layer 30, the formation of an imine bond is described in the formation of a crosslinked structure in the adhesive polyimide, but is not limited thereto, and as a hardening method for the adhesive layer 30, for example, epoxy resin, an epoxy resin hardener, or the like can be compounded and hardened.

[0151] <Thickness of the resin layer>

[0152] Regarding the metal-clad laminate 100, when the total thickness of the thickness T3 of the insulating resin layer 10 and the thickness T2 of the adhesive layer 30 is T1, the total thickness T1 is in the range of 50 μm to 250 μm, and preferably in the range of 70 μm to 150 μm. If the total thickness T1 is less than 50 μm, the effect of reducing transmission loss when a multilayer circuit substrate is manufactured using the metal-clad laminate 100 is insufficient, and if it exceeds 250 μm, there is a concern that productivity is reduced.

[0153] In addition, the thickness T2 of the adhesive layer 30 is preferably, for example, in the range of 20 μm to 200 μm, and more preferably in the range of 20 μm to 100 μm. If the thickness T2 of the adhesive layer 30 is less than the lower limit value, the transmission loss is sometimes large with respect to a high-frequency substrate. On the other hand, if the thickness T2 of the adhesive layer 30 exceeds the upper limit value, adverse situations such as a reduction in dimensional stability are sometimes generated.

[0154] In addition, the ratio (T2 / T1) of the thickness T2 of the adhesive layer 30 to the total thickness T1 is in the range of 0.5 to 0.8, and preferably in the range of 0.5 to 0.7. If the ratio (T2 / T1) is less than 0.5, it is difficult to set the total thickness T1 to be 50 μm or more, and if it exceeds 0.8, adverse situations such as a reduction in dimensional stability are generated.

[0155] The thickness T3 of the insulating resin layer 10 is preferably, for example, in the range of 12 μm to 100 μm, and more preferably in the range of 12 μm to 50 μm. If the thickness T3 of the insulating resin layer 10 is less than the lower limit value, problems such as warping of the metal-clad laminate 100 are sometimes generated. If the thickness T3 of the insulating resin layer 10 exceeds the upper limit value, adverse situations such as a reduction in productivity are generated.

[0156] In the metal-clad laminate 100 of the present embodiment, in order to realize low dielectric loss tangent of the entire resin layer and to cope with high-frequency transmission, the thickness T2 of the adhesive layer 30 is itself increased. However, in general, a material having a low elastic modulus exhibits a high coefficient of thermal expansion, and thus there is a concern that increasing the layer thickness leads to a reduction in dimensional stability. Here, it is considered that dimensional changes generated when the metal-clad laminate 100 is subjected to circuit processing and is multilayered are mainly generated due to the following a) to c) mechanisms, and the total amount of b) and c) is exhibited as a dimensional change after etching.

[0157] a) When the metal-clad laminate 100 is manufactured, internal stress is accumulated in the resin layer.

[0158] b) When the circuit is processed, the internal stress accumulated in a) is released by etching the metal layer 20, and the resin layer expands or shrinks.

[0159] c) When the circuit is processed, the resin exposed by etching the metal layer 20 absorbs moisture and expands.

[0160] The main causes of the internal stress of a) are: 1) the difference in the thermal expansion coefficients of the metal layer 20 and the resin layer; and 2) the internal strain of the resin generated by film formation. Here, the magnitude of the internal stress caused by 1) is not only affected by the difference in the thermal expansion coefficients, but also by the temperature difference ΔT from the temperature (heating temperature) at the time of lamination to the temperature at the time of cooling and solidification when multilayer circuiting is performed. That is, the internal stress becomes larger in proportion to the temperature difference ΔT, and therefore, even if the difference in the thermal expansion coefficients of the metal layer 20 and the resin layer is small, the more the resin requires a high temperature at the time of lamination, the larger the internal stress becomes. In the metal-clad laminate 100 of the present embodiment, by using the adhesive layer 30 that satisfies the conditions (i) to (iii) as the adhesive layer 30, the internal stress is reduced and the dimensional stability is ensured. In addition, the adhesive layer 30 is laminated to the insulating resin layer 10, and therefore, in the case of forming a multilayer circuit substrate, functions as an intermediate layer and warping and dimensional changes are suppressed.

[0161] [Method of manufacturing metal-clad laminate]

[0162] The metal-clad laminate 100 can be manufactured, for example, by the following Method 1 or Method 2.

[0163] [Method 1]

[0164] A method in which a resin composition that will become the adhesive layer 30 is formed into a film shape and made into an adhesive film, the adhesive film is arranged and attached in a manner facing the insulating resin layer 10 of the single-sided metal-clad laminate 40, and heat pressure bonding is performed.

[0165] [Method 2]

[0166] A method in which a solution of a resin composition that will become the adhesive layer 30 is applied to the insulating resin layer 10 of the single-sided metal-clad laminate 40 in a prescribed thickness and dried. In this case, heating and the like to perform a hardening reaction or a crosslinking reaction can also be performed as necessary.

[0167] The adhesive film used in the method 1 can be produced, for example, by coating a solution of the resin composition to be the adhesive layer 30 on an arbitrary support substrate and drying, and then peeling from the support substrate. As the adhesive film, an adhesive polyimide film produced by forming the adhesive polyimide into a film shape can also be used. As the production method of the adhesive polyimide film, for example, the following methods can be listed: [1] a method of coating a solution of a polyamic acid on a support substrate and drying, and then peeling from the support substrate to produce an adhesive film by imidization through heat treatment; [2] a method of coating a solution of a polyamic acid on a support substrate and drying, and then peeling a gel film of the polyamic acid from the support substrate, and then producing an adhesive film by imidization through heat treatment; and [3] a method of coating a solution of an adhesive polyimide on a support substrate and drying, and then peeling from the support substrate to produce an adhesive film. Among the above [1] to [3], the method of [3] using coating of a solution of an adhesive polyimide in which imidization is completed in a polyamic acid solution on a support substrate and drying is preferable. Since the adhesive polyimide is solvent-soluble, the polyamic acid is imidized in a solution state, and can be directly used as a coating solution of the adhesive polyimide, and thus is advantageous. Further, the adhesive polyimide constituting the adhesive film can also be cross-linked by the above method.

[0168] In the method 1 and the method 2, the method of coating a solution of the resin composition to be the adhesive layer 30 on a support substrate or the insulating resin layer 10 is not particularly limited, and coating can be performed, for example, using a coater such as a doctor blade, a die, a knife, a lip, or the like. In the formation step of the adhesive layer 30, the surface of the formed adhesive layer 30 is preferably made flat. Further, the thickness of the adhesive layer 30 is preferably also made uniform. By making the surface of the adhesive layer 30 flat and the thickness uniform, the adhesiveness in the production process of the multilayer circuit board is improved.

[0169] The metal-clad laminate 100 of the present embodiment obtained as above can be produced into a single-sided FPC or a double-sided FPC by circuit processing of the metal layer 20, and in addition thereto, a plurality of single-sided FPCs or double-sided FPCs can be laminated using the adhesiveness of the adhesive layer 30 or using an arbitrary bonding sheet or the like, and thus a multilayer circuit board can be produced.

[0170] [Circuit Substrate]

[0171] Figure 2is a cross-sectional view showing the structure of a circuit board according to an embodiment of the present application. The circuit board 101 includes an insulating resin layer 10, a conductor circuit layer 50 laminated on one surface of the insulating resin layer 10, and an adhesive layer 30 laminated on the other surface of the insulating resin layer 10. That is, the circuit board 101 has a structure in which the conductor circuit layer 50, the insulating resin layer 10, and the adhesive layer 30 are laminated in this order. The circuit board 101 according to the present embodiment is obtained by subjecting the metal layer 20 of the metal-clad laminate 100 to wiring circuit processing.

[0172] (conductor circuit layer)

[0173] The conductor circuit layer 50 is a layer in which a conductor circuit is formed in a predetermined pattern on one surface of the insulating resin layer 10. For example, a photosensitive resist is applied to the metal layer 20 of the metal-clad laminate 100, and exposure and development are performed to form a predetermined mask pattern. After etching the metal layer 20 through the mask pattern, the mask pattern is removed, whereby the conductor circuit layer 50 having a predetermined pattern can be formed. Further, the "conductor circuit layer" refers to an in-plane connection electrode (land electrode) formed in the surface direction of the insulating resin layer 10, which is distinguished from an interlayer connection electrode (via electrode).

[0174] With respect to the conductor circuit layer 50, the maximum height roughness (Rz) of the surface in contact with the insulating resin layer 10 is preferably 1.0 μm or less from the viewpoint of reducing transmission loss in high-frequency transmission. The transmission loss includes the sum of conductor loss and dielectric loss, and if the Rz of the conductor circuit layer 50 is large, the conductor loss becomes large, and this adversely affects the transmission loss. Therefore, it is preferable to control the Rz.

[0175] The insulating resin layer 10 and the adhesive layer 30 in the circuit board 101 according to the present embodiment are configured as described in the metal-clad laminate 100.

[0176] [multilayer circuit board]

[0177] Next, the circuit board 101 according to the present embodiment will be described with reference to FIG. 2. Figures 3 to 6The multilayer circuit board of the present embodiment will be described. Generally, the multilayer circuit board has a laminate including a plurality of insulating resin layers, and two or more conductor circuit layers embedded in the interior of the laminate, and preferably has two or more insulating resin layers and two or more conductor circuit layers. Here, two preferred embodiments of the multilayer circuit board will be described. The multilayer circuit board 200, multilayer circuit board 201 of the present embodiment include one or more of the circuit board 101. In addition, the multilayer circuit board 200, multilayer circuit board 201 of the present embodiment can include one or more arbitrary circuit boards 110 laminated to the circuit board 101 other than the circuit board 101.

[0178] <First Embodiment>

[0179] Figure 3 is a cross-sectional view in the lamination direction showing the structure of the multilayer circuit board 200 of the first embodiment of the present application. The multilayer circuit board 200 of the first embodiment is a structure in which a plurality of circuit boards 101 and an arbitrary circuit board 110 are laminated in the same direction.

[0180] That is, from the top to the bottom in the Figure 3 first circuit board 101 is joined and laminated so as to cover the conductor circuit layer 50 of the second circuit board 101, and further, the adhesive layer 30 of the second circuit board 101 is joined and laminated so as to cover the conductor circuit layer 50 of the arbitrary circuit board 110 which does not have an adhesive layer 30. Here, the structure or material of the arbitrary circuit board 110 is not limited, and for example, the conductor circuit layer 50 can be formed of a patterned metal layer 20, or can have a damascene structure conductor circuit layer 50. In addition, the conductor circuit layer 50 of the arbitrary circuit board 110 can be formed on the insulating resin layer 10 by inkjet, sputtering, plating, or the like. Further, the thickness, material, physical properties, or the like of the conductor circuit layer 50 or the insulating resin layer 10 of the arbitrary circuit board 110 are not particularly limited.

[0181] Figure 3 In the above, the laminated structure of two circuit boards 101 and one arbitrary circuit board 110 is shown, and three or more circuit boards 101 can also be laminated. In addition, the adhesive layer 30 can cover all of the conductor circuit layer 50 of the adjacent circuit board 101 or arbitrary circuit board 110, or can cover a portion thereof. Further, in the multilayer circuit board 200, the conductor circuit layer 50 can be exposed on the surface of the uppermost circuit board 101, and an arbitrary protective film covering the uppermost conductor circuit layer 50 can also be provided. In addition, Figure 3In the present embodiment, as the arbitrary circuit board 110, a case where the conductor circuit layer 50 is formed on one surface of the insulating resin layer 10 is exemplified, and the conductor circuit layer 50 can be formed on both surfaces of the insulating resin layer 10, respectively.

[0182] Figure 4 A manufacturing process diagram of the multilayer circuit board 200 of the first embodiment. First, a plurality of circuit boards 101 and an arbitrary circuit board 110 are prepared. Then, the adhesive layer 30 of the first circuit board 101 is overlaid and arranged so as to face the conductor circuit layer 50 of the second circuit board 101, and the adhesive layer 30 of the second circuit board 101 is overlaid and arranged so as to face the conductor circuit layer 50 of the arbitrary circuit board 110 which does not have the adhesive layer 30, and these are pressure-bonded together, whereby the manufacturing can be performed (pressure-bonding process). Further, in the present embodiment, an example where two circuit boards 101 are laminated is shown, and three or more circuit boards 101 can be laminated at a time. In addition, the arbitrary circuit board 110 is not limited to one, and a plurality of arbitrary circuit boards 110 can be laminated. Figure 4

[0183] The adhesive layer 30 of the circuit board 101, because its surface is planarized, does not generate a gap or the like in the adhesive layer 30 in the pressure-bonding process, and can be laminated in a state where the adhesive resin is filled between the conductor circuits of the conductor circuit layer 50. In addition, as necessary, the multilayer circuit board 200 obtained by lamination is pressed from both sides using a press roller or a press device, and the thickness adjustment process of adjusting the thickness of the adhesive layer 30 can be performed. By the thickness adjustment process, the thickness accuracy of the adhesive layer 30 and the entire multilayer circuit board 200 can be improved. Further, at the time of pressure-bonding, for example, a heating treatment of heating at a temperature of 60°C to 220°C can be performed. Thereby, the multilayer circuit board 200 in which a plurality of circuit boards are integrally laminated can be manufactured. At the time of the heating treatment, in the adhesive layer 30, for example, a crosslinked structure of an imine bond can be formed by heat condensation of the adhesive polyimide.

[0184] In the present embodiment, the adhesive layer 30 of each circuit board 101 has a function of the adhesive sheet which adheres the circuit boards to each other, and a function of the protective film which protects the conductor circuit. Therefore, it is not necessary to separately prepare an adhesive sheet or a protective layer for the conductor circuit and interpose it between the circuit boards, and simplification of the process and the equipment, and simplification of the materials and cost reduction for forming a multilayer circuit can be achieved.

[0185] ​The multilayer circuit board 200 obtained as described above includes the following configuration: an adhesive layer 30 of sufficient thickness is provided between the conductor circuit layer 50 and the insulating resin layer 10 to ensure insulation, flexibility, and low dielectric properties. Furthermore, in the multilayer circuit board 200 of this embodiment, a protective layer such as a cover film or solder resist may be provided as needed. Additionally, although not shown in the figures, chip-type electronic components such as IC chips, chip capacitors, chip coils, and chip resistors may be embedded inside the multilayer circuit board 200 of this embodiment. Furthermore, in the multilayer circuit board 200 of this embodiment, interlayer connection electrodes (through-hole electrodes) (not shown) may also be formed. Interlayer connection electrodes can be formed by forming through-holes in the insulating resin layer 10 using laser processing or drilling, and then filling them with conductive paste using printing or the like. The conductive paste, for example, can be a conductive paste made by mixing an organic solvent or epoxy resin with a tin-based conductive powder. In addition, after the via is formed, the interlayer connection electrode can be plated on the inner surface of the via and a portion of the surface of the conductor circuit layer 50.

[0186] <Second Implementation>

[0187] Figure 5 This is a cross-sectional view in the stacking direction showing the structure of the multilayer circuit board 201 according to the second embodiment of the present invention. In the multilayer circuit board 201 of the second embodiment, a circuit board unit 102 is defined as a structure formed by bonding a pair of circuit boards 101 together with these adhesive layers 30 facing each other, and includes at least one of the circuit board units 102.

[0188] That is, since Figure 5 The circuit board unit 102, a first metal-clad laminate 100, and a second metal-clad laminate 100 (oriented in the opposite direction to the first metal-clad laminate 100) are arranged sequentially from top to bottom, and are stacked such that the circuit board unit 102 is sandwiched between the adhesive layers 30 of the two metal-clad laminates 100. The adhesive layer 30 of the first metal-clad laminate 100 is stacked in contact with the conductor circuit layer 50 on one side (the upper side in the figure) of the circuit board unit 102, and the adhesive layer 30 of the second metal-clad laminate 100 is stacked in contact with the conductor circuit layer 50 on the other side (the lower side in the figure) of the circuit board unit 102. Furthermore, Figure 5 The diagram shows a stacked structure containing only one circuit board unit 102. A stacked structure containing multiple circuit board units 102 can also be formed by further separating an adhesive sheet or circuit board 101 or any circuit board 110. Additionally, the circuit board 101 can also be used as one or both of the upper and lower metal-clad laminates 100.

[0189] Figure 6 A manufacturing process diagram of the multilayer circuit board 201 of the second embodiment. First, one circuit board unit 102 and two metal-clad laminated boards 100 are prepared. Here, the circuit board unit 102 can be produced by preparing a pair of circuit boards 101 and adhering the adhesive layer 30 of one of the circuit boards 101 to the adhesive layer 30 of the other circuit board 101. Also, the multilayer circuit board 201 can be produced by arranging the adhesive layer 30 of the first metal-clad laminated board 100 so as to face the conductor circuit layer 50 on the upper surface side of the circuit board unit 102, and further, arranging the adhesive layer 30 of the second metal-clad laminated board 100 so as to face the conductor circuit layer 50 on the lower surface side of the circuit board unit 102, and pressure-bonding these together (pressure-bonding process).

[0190] Further, instead of producing the circuit board unit 102, the adhesive layer 30 of the first metal-clad laminated board 100 can be arranged so as to face the conductor circuit layer 50 of the upper circuit board 101, the adhesive layer 30 of the upper circuit board 101 and the adhesive layer 30 of the lower circuit board 101 can be arranged so as to face each other, and further, the adhesive layer 30 of the second metal-clad laminated board 100 can be arranged so as to face the conductor circuit layer 50 of the lower circuit board 101, and these can be pressure-bonded together.

[0191] If necessary, the multilayer circuit board 201 obtained by laminating from both sides can be pressed using a press roller or a press device, and thus a thickness adjustment process for adjusting the thickness of the adhesive layer 30 can be performed. By the thickness adjustment process, the thickness accuracy of the adhesive layer 30 and the entire multilayer circuit board 201 can be improved. Further, at the time of pressure-bonding, for example, a heating process can be performed in which heating is performed at a temperature of 60°C to 220°C. Thus, a multilayer circuit board 201 in which a plurality of circuit boards are integrally laminated can be produced. At the time of the heating process, for example, a cross-linking structure in which an imine bond is formed by heat condensation of the adhesive polyimide can be formed in the adhesive layer 30.

[0192] In the present embodiment, the adhesive layer 30 of each circuit board 101 also has a function as an adhesive sheet for adhering the circuit boards to each other. Therefore, it is not necessary to separately prepare an adhesive sheet and interpose it between the circuit boards, and simplification of the process and equipment for forming a multilayer circuit, simplification of the materials, and cost reduction can be achieved.

[0193] The other configurations and effects of the multilayer circuit board 201 of the present embodiment are the same as those of the multilayer circuit board 200 of the first embodiment.

[0194] [Embodiment]

[0195] The following shows examples and more specifically explains the features of the present application. The scope of the present application is not limited to the examples. Further, in the following examples, unless otherwise specified, various measurements and evaluations are based on the following.

[0196] [Measurement of dimensional change rate]

[0197] The measurement of the dimensional change rate was performed in the following order. First, a 150 mm square test piece was used to expose and develop the dry film resist at 100 mm intervals, thereby forming a target for position measurement. In an environment of temperature 23 ± 2°C and relative humidity 50 ± 5%, the dimension before etching (normal state) was measured, after which the copper of the test piece except for the target was removed by etching (liquid temperature 40°C or lower, time 10 minutes or less). After standing for 24 ± 4 hours in an environment of temperature 23 ± 2°C and relative humidity 50 ± 5%, the dimension after etching was measured. The dimensional change rate with respect to the normal state was calculated for each of three sites in the MD direction (long side direction) and the TD direction (width direction), and the average of each was taken as the dimensional change rate after etching. The dimensional change rate after etching was calculated using the following equation.

[0198] Dimensional change rate after etching (%) = (B - A) / A x 100

[0199] A: distance between targets before etching

[0200] B: distance between targets after etching

[0201] Next, the test piece was subjected to a heating treatment using an oven at 250°C for 1 hour, and the distance between the position targets after this was measured. The dimensional change rate with respect to the dimension after etching was calculated for each of three sites in the MD direction (long side direction) and the TD direction (width direction), and the average of each was taken as the dimensional change rate after the heating treatment. The dimensional change rate after heating was calculated using the following equation.

[0202] Dimensional change rate after heating (%) = (C - B) / B x 100

[0203] B: distance between targets after etching

[0204] C: distance between targets after heating

[0205] [Measurement of viscosity]

[0206] The viscosity at 25°C was measured using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro). The number of revolutions was set so that the torque was 10% to 90%, and the value at the time when the viscosity became stable was read after 2 minutes from the start of measurement.

[0207] [Measurement of coefficient of thermal expansion (CTE)]

[0208] The average coefficient of thermal expansion (coefficient of thermal expansion) from 250°C to 100°C was obtained by using a thermomechanical analyzer (manufactured by Bruker, trade name: 4000SA) for a polyimide film of 3 mm x 20 mm size, applying a load of 5.0 g while increasing the temperature from 30°C to 300°C at a certain temperature increase rate, and then cooling at a rate of 5°C / min after keeping the temperature for 10 minutes, and the average coefficient of thermal expansion (coefficient of thermal expansion) from 250°C to 100°C was obtained.

[0209] [Measurement of Storage Elastic Modulus and Glass Transition Temperature (Tg)]

[0210] A dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F) was used for a resin sheet of 5 mm x 20 mm size, and measurement was performed under conditions of a temperature increase rate of 4°C / min from 30°C to 400°C and a frequency of 11 Hz. In addition, the temperature at which the elastic modulus change (tan δ) was the largest was set as the glass transition temperature.

[0211] [Measurement of Dielectric Constant and Dielectric Loss Tangent]

[0212] A vector network analyzer (manufactured by Agilent, trade name: E8363C) and a split post dielectric resonator (SPDR) were used to measure the dielectric constant and dielectric loss tangent of a resin sheet at 10 GHz. Furthermore, the material used in the measurement was left to stand for 24 hours under conditions of a temperature of 24°C to 26°C and a humidity of 45% to 55% RH.

[0213] [Measurement of Surface Roughness of Copper Foil]

[0214] An atomic force microscope (AFM) (manufactured by Bruker AXS, trade name: Dimension Icon type scanning probe microscope (SPM)), a probe (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip radius of curvature 10 nm, spring constant 42 N / m) were used to measure a range of 80 μm x 80 μm of the surface of a copper foil in a tapping mode, and the ten-point average roughness (Rzjis) was obtained.

[0215] The abbreviations used in the synthesis examples represent the following compounds.

[0216] o BPDA: 3,3',4,4'-Biphenyltetracarboxylic dianhydride

[0217] o BPADA: 2,2-Bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride

[0218] o PMDA: Pyromellitic dianhydride

[0219] o BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride

[0220] o m-TB: 2,2'-Dimethyl-4,4'-diaminobiphenyl

[0221] o TPE-R: 1,3-Bis(4-aminophenoxy)benzene

[0222] o Bis-aniline-M: 1,3-Bis[2-(4-aminophenyl)-2-propyl]benzene

[0223] o BAPP: 2,2-Bis[4-(4-aminophenoxy)phenyl]propane

[0224] o DDA: Aliphatic diamine having a carbon number of 36 (manufactured by CRODA Japan Co., Ltd., trade name: PRIAMINE 1074, amine value: 205 mgKOH / g, mixture of dimer diamine of cyclic structure and chain structure, content of dimer component: 95% by weight or more)

[0225] o DMAc: N,N-Dimethylacetamide

[0226] o NMP: N-Methyl-2-pyrrolidone

[0227] o N-12: Dodecanedioic acid dihydrazide

[0228] o OP935: Aluminum salt of organic phosphinic acid (manufactured by Clariant Japan Co., Ltd., trade name: Exolit OP935)

[0229] o R710: (trade name, manufactured by Printec Co., Ltd., bisphenol-type epoxy resin, epoxy equivalent weight: 170, liquid at normal temperature, weight average molecular weight: about 340)

[0230] o VG3101L: (trade name, manufactured by Printec Co., Ltd., multifunctional epoxy resin, epoxy equivalent weight: 210, softening point: 39°C to 46°C)

[0231] o SR35K: (trade name, manufactured by Printec Co., Ltd., epoxy resin, epoxy equivalent: 930 to 940, softening point: 86°C to 98°C)

[0232] o YDCN-700-10: (trade name, manufactured by Nippon Steel Chemical & Material Co., Ltd., cresol novolak type epoxy resin, epoxy equivalent 210, softening point 75°C to 85°C)

[0233] o milex XLC-LL: (trade name, manufactured by Mitsui Chemicals, Inc., phenol resin, hydroxyl equivalent: 175, softening point: 77°C, water absorption: 1 mass%, mass reduction rate by heating: 4 mass%)

[0234] o HE200C-10: (trade name, manufactured by AIR WATER, Inc., phenol resin, hydroxyl equivalent: 200, softening point: 65°C to 76°C, water absorption: 1 mass%, mass reduction rate by heating: 4 mass%)

[0235] o HE910-10: (trade name, manufactured by AIR WATER, Inc., phenol resin, hydroxyl equivalent: 101, softening point: 83°C, water absorption: 1 mass%, mass reduction rate by heating: 3 mass%)

[0236] o SC1030-HJA: (trade name, manufactured by Admatechs Co., Ltd., silica filler dispersion liquid, average particle diameter: 0.25 μm)

[0237] o Aerosil R972: (trade name, manufactured by Aerosil Japan Co., Ltd., silica, average particle diameter: 0.016 μm)

[0238] o Acryl gum HTR-860P-30B-CHN: (sample name, manufactured by Teikoku Chemical Industry Co., Ltd., weight average molecular weight: 230,000, glycidyl functional monomer ratio: 8%, Tg: -7°C)

[0239] o Acryl gum HTR-860P-3CSP: (sample name, manufactured by Teikoku Chemical Industry Co., Ltd., weight average molecular weight: 800,000, glycidyl functional monomer ratio: 3%, Tg: -7°C)

[0240] o A-1160: (trade name, manufactured by GE Toshiba Silicones Co., Ltd., γ-ureidopropyl triethoxysilane)

[0241] o A-189: (trade name, manufactured by GE Toshiba Silicones Co., Ltd., γ-mercaptopropyl trimethoxysilane)

[0242] o Curezol 2PZ-CN: (trade name, manufactured by Shikoku Chemicals Corporation, 1-cyanoethyl-2-phenylimidazole)

[0243] o RE-810NM: (trade name, manufactured by Nippon Kayaku Co., Ltd., Diallyl bisphenol A diglycidyl ether (property: liquid))

[0244] o Phoret SCS: (trade name: manufactured by Soken Chemical & Engineering Co., Ltd., styrene group-containing acrylic polymer (Tg: 70°C, weight average molecular weight: 15,000))

[0245] o BMI-1: (trade name, manufactured by Tokyo Chemical Industry Co., Ltd., 4,4'-bismaleimidediphenylmethane)

[0246] o TPPK: (trade name: manufactured by Tokyo Chemical Industry Co., Ltd., tetraphenylphosphonium tetraphenylborate)

[0247] o HP-P1: (trade name, manufactured by Sumitomo Metal Industries, Ltd., boron nitride filler)

[0248] (Synthetic Example 1)

[0249] Preparation of Resin Solution A for Adhesive Layer

[0250] A composition containing an epoxy resin and a phenol resin as (a) thermosetting resin and an inorganic filler as (c) inorganic filler, which are the trade name and composition ratio (unit: mass parts) in Table 1, was added with cyclohexanone and stirred and mixed. To this, an acrylic rubber as (b) high molecular weight component shown in Table 1 was added and stirred, and further, a coupling agent as (e) and a hardening accelerator as (d) shown in Table 1 were added and stirred until each component became uniform, to obtain a resin solution A for adhesive layer.

[0251] [Table 1]

[0252]

[0253] (Synthetic Example 2)

[0254] Synthesis of Polyimide Resin (PI-1) and Preparation of Resin Solution B for Adhesive Layer

[0255] In a 300 mL flask equipped with a thermometer, a stirrer, a cooling tube, and a nitrogen inlet tube, 15.53 g of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: LP-7100), 28.13 g of polyoxypropylenediamine (manufactured by BASF SE, trade name: D400, molecular weight: 450), and 100.0 g of NMP were placed and stirred to prepare a reaction solution. After the diamine was dissolved, the flask was cooled in an ice bath while 32.30 g of 4,4'-oxydiphthalic dianhydride, which was previously purified by recrystallization from anhydrous acetic acid, was added to the reaction solution in small amounts at a time. After 8 hours of reaction at normal temperature (25°C), 67.0 g of xylene was added, and heating was performed at 180°C while blowing nitrogen, whereby xylene was removed together with water by azeotropy. The reaction solution was poured into a large amount of water, the precipitated resin was taken by filtration, and dried to obtain a polyimide resin (PI-1). The molecular weight of the obtained polyimide resin (PI-1) was measured by gel permeation chromatography (GPC), and as a result, the number average molecular weight Mn = 22400 and the weight average molecular weight Mw = 70200 in terms of polystyrene.

[0256] Using the obtained polyimide resin (PI-1) and blending the components at the composition ratio (unit: mass parts) shown in Table 2, a resin solution B for an adhesive layer was obtained.

[0257] [Table 2]

[0258]

[0259] (Synthesis Example 3)

[0260] Preparation of Resin Solution C for Adhesive Layer

[0261] In a 500 mL four-necked flask equipped with a nitrogen inlet tube, a stirrer, a thermocouple, a Dean-Stark trap, and a cooling tube, 44.92 g of BTDA (0.139 mol), 75.08 g of DDA (0.141 mol), 168 g of NMP, and 112 g of xylene were charged, and mixed at 40°C for 30 minutes to prepare a polyamic acid solution. The polyamic acid solution was warmed to 190°C, heated for 4 hours with stirring, and water and xylene distilled out of the system. Thereafter, it was cooled to 100°C, 112 g of xylene was added and stirred, and further cooled to 30°C to complete imidization, and a resin solution C for an adhesive layer was obtained (solid content: 29.5% by weight, weight average molecular weight: 75,700).

[0262] (Synthetic Example 4)

[0263] Preparation of Resin Solution D for Adhesive Layer

[0264] Using 42.51 g of BPADA (0.082 mol), 34.30 g of DDA (0.066 mol), 6.56 g of BAPP (0.016 mol), 208 g of NMP, and 112 g of xylene as raw material components, a polyamic acid solution was prepared in the same manner as in Synthetic Example 3. The polyamic acid solution was treated in the same manner as in Synthetic Example 3, and a resin solution D for adhesive layer (solid content: 30.0 wt%, weight average molecular weight: 65,000) was obtained.

[0265] (Synthetic Example 5)

[0266] Preparation of Polyamic Acid Solution 1 for Insulating Resin Layer

[0267] Under a nitrogen stream, 64.20 g of m-TB (0.302 mol) and 5.48 g of bisaniline-M (0.016 mol) and DMAc in an amount such that the solid content concentration after polymerization was 15 wt% were charged into a reaction vessel, and stirring was performed at room temperature to dissolve them. Next, 34.20 g of PMDA (0.157 mol) and 46.13 g of BPDA (0.157 mol) were added, and then stirring was continued at room temperature for 3 hours to perform a polymerization reaction, and a polyamic acid solution 1 (viscosity: 26,500 cps) was prepared.

[0268] (Synthetic Example 6)

[0269] Preparation of Polyamic Acid Solution 2 for Insulating Resin Layer

[0270] Using 69.56 g of m-TB (0.328 mol), 542.75 g of TPE-R (1.857 mol), DMAc in an amount such that the solid content concentration after polymerization was 12 wt%, 194.39 g of PMDA (0.891 mol), and 393.31 g of BPDA (1.337 mol) as raw material components, a polyamic acid solution 2 (viscosity: 2,650 cps) was prepared in the same manner as in Synthetic Example 3.

[0271] (Production Example 1)

[0272] Preparation of Resin Sheet A for Adhesive Layer

[0273] The resin solution A for the adhesive layer was applied to the silicone-treated surface of a release base (length x width x thickness = 320 mm x 240 mm x 25 μm) in a manner such that the dried thickness was 50 μm, and then dried at 80°C for 15 minutes and further dried at 120°C for 15 minutes, after which it was peeled from the release base, thereby producing a resin sheet A. In addition, the resin sheet A was heated in an oven at 120°C for 2 hours and at 170°C for 3 hours in order to evaluate the properties after hardening. At this time, the Tg of the resin sheet A after hardening was 95°C, the storage elastic modulus at 50°C was 960 MPa, and the maximum value of the storage elastic modulus in the range from 180°C to 260°C was 7 MPa.

[0274] (Production Example 2)

[0275] <Preparation of Resin Sheet B for Adhesive Layer>

[0276] The resin solution B for the adhesive layer was applied to the silicone-treated surface of a release base (length x width x thickness = 320 mm x 240 mm x 25 μm) in a manner such that the dried thickness was 50 μm, and then dried at 80°C for 15 minutes and further dried at 120°C for 15 minutes, after which it was peeled from the release base, thereby producing a resin sheet B. In addition, the resin sheet B was heated in an oven at 120°C for 2 hours and at 170°C for 3 hours in order to evaluate the properties after hardening. At this time, the Tg of the resin sheet B after hardening was 100°C or less, the storage elastic modulus at 50°C was 1800 MPa or less, and the maximum value of the storage elastic modulus in the range from 180°C to 260°C was 70 MPa.

[0277] (Production Example 3)

[0278] <Preparation of Resin Sheet C for Adhesive Layer>

[0279] The polyimide varnish 1 was prepared by formulating 1.8 g of N-12 (0.0036 moles) and 12.5 g of OP935 in 169.49 g (50 g in terms of solid content) of the resin solution C for the adhesive layer, and diluting with 6.485 g of NMP and 19.345 g of xylene.

[0280] A resin sheet C was produced by applying polyimide varnish 1 to the silicone-treated surface of a release substrate (length x width x thickness = 320 mm x 240 mm x 25 μm) in a dried thickness of 50 μm, followed by heating and drying at 80°C for 15 minutes, and peeling from the release substrate. The resin sheet C had a Tg of 78°C, a storage elastic modulus at 50°C of 800 MPa, and a maximum value of the storage elastic modulus in the range from 180°C to 260°C of 10 MPa. In addition, the dielectric constant (Dk) and the dielectric loss tangent (Df) were 2.68 and 0.0028, respectively.

[0281] (Production Example 4)

[0282] <Production of Resin Sheet D for Adhesive Layer>

[0283] A resin sheet D was produced by applying resin solution D for adhesive layer to the silicone-treated surface of a release substrate (length x width x thickness = 320 mm x 240 mm x 25 μm) in a dried thickness of 50 μm, followed by heating and drying at 80°C for 15 minutes, and peeling from the release substrate. The resin sheet D had a Tg of 82°C, a storage elastic modulus at 50°C of 1800 MPa or less, and a maximum value of the storage elastic modulus in the range from 180°C to 260°C of 2 MPa or less. In addition, the dielectric constant (Dk) and the dielectric loss tangent (Df) were 2.80 and 0.0026, respectively.

[0284] (Production Example 5)

[0285] <Production of Single-Sided Metal-Clad Laminate>

[0286] A polyamide acid solution 2 was uniformly applied to a copper foil 1 (electrolytic copper foil, thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) in a hardened thickness of about 2 μm to 3 μm, followed by heating and drying at 120°C to remove the solvent. Next, a polyamide acid solution 1 was uniformly applied thereto in a hardened thickness of about 21 μm, followed by heating and drying at 120°C to remove the solvent. Further, a polyamide acid solution 2 was uniformly applied thereto in a hardened thickness of about 2 μm to 3 μm, followed by heating and drying at 120°C to remove the solvent. Further, a heat treatment was performed from 120°C to 360°C in stages to complete imidization, and a single-sided metal-clad laminate 1 was produced. The dimensional change rate of the single-sided metal-clad laminate 1 was as follows.

[0287] Dimensional change rate after etching in the MD direction (longitudinal direction): 0.01%

[0288] Dimensional change rate after etching in the TD direction (width direction): -0.04%

[0289] MD direction (long side direction) : -0.03%

[0290] TD direction (width direction) : -0.01%

[0291] In addition, the CTE of a polyimide film 1 (thickness: 25 μm) prepared by etching and removing the copper foil 1 of the single-sided metal-clad laminate 1 using an aqueous ferric chloride solution was 20.0 ppm / K, and the dielectric constant (Dk) and the dielectric loss tangent (Df) were 3.40 and 0.0029, respectively.

[0292] [Example 1]

[0293] The resin solution A for the adhesive layer was applied to the resin surface of the single-sided metal-clad laminate 1 in a manner such that the dried thickness was 50 μm, and then dried at 80°C for 15 minutes, and further dried at 120°C for 15 minutes, thereby preparing a single-sided metal-clad laminate 1 with an adhesive layer. In addition, the single-sided metal-clad laminate 1 with an adhesive layer was heated in an oven at 120°C for 2 hours and at 170°C for 3 hours in order to evaluate the properties after hardening of the adhesive layer. The evaluation results of the single-sided metal-clad laminate 1 with an adhesive layer after heating are described below.

[0294] MD direction : -0.05%

[0295] TD direction : -0.02%

[0296] MD direction : -0.01%

[0297] TD direction : -0.03%

[0298] The dimensional change of the single-sided metal-clad laminate 1 with an adhesive layer after heating was not problematic. In addition, the CTE of a resin laminate 1 (thickness: 75 μm) prepared by etching and removing the copper foil 1 of the single-sided metal-clad laminate 1 with an adhesive layer after heating was 26.2 ppm / K.

[0299] [Example 2]

[0300] The resin solution B for the adhesive layer was applied to the resin surface of the single-sided metal-clad laminate 1 in a manner such that the dried thickness was 50 μm, and then dried at 80°C for 15 minutes, and further dried at 120°C for 15 minutes, thereby preparing a single-sided metal-clad laminate 2 with an adhesive layer. In addition, the single-sided metal-clad laminate 2 with an adhesive layer was heated in an oven at 120°C for 2 hours and at 170°C for 3 hours in order to evaluate the properties after hardening of the adhesive layer. The evaluation results of the single-sided metal-clad laminate 2 with an adhesive layer after heating are described below.

[0301] Etching after size change rate in MD direction: -0.08%

[0302] Etching after size change rate in TD direction: -0.06%

[0303] Heating after size change rate in MD direction: -0.03%

[0304] Heating after size change rate in TD direction: -0.06%

[0305] The size change of the adhesive layer-attached single-sided metal-clad laminate 2 after heating was not problematic. In addition, the CTE of a resin laminate 2 (thickness: 75 μm) prepared by etching away the copper foil 1 of the adhesive layer-attached single-sided metal-clad laminate 2 after heating was 25.0 ppm / K.

[0306] [Example 3]

[0307] The polyimide varnish 1 was applied to the resin side of the single-sided metal-clad laminate 1 in such a manner that the thickness after drying was 50 μm, and then, heat-dried at 80°C for 15 minutes, thereby preparing an adhesive layer-attached single-sided metal-clad laminate 3. In addition, with respect to the adhesive layer-attached single-sided metal-clad laminate 3, evaluation was performed after heating in an oven at 180°C for 1 minute and at 150°C for 30 minutes, and the results were as described below.

[0308] Etching after size change rate in MD direction: -0.05%

[0309] Etching after size change rate in TD direction: -0.04%

[0310] Heating after size change rate in MD direction: 0.05%

[0311] Heating after size change rate in TD direction: 0.01%

[0312] The size change of the adhesive layer-attached single-sided metal-clad laminate 3 after heating was not problematic. In addition, the CTE of a resin laminate 3 (thickness: 75 μm) prepared by etching away the copper foil 1 of the adhesive layer-attached single-sided metal-clad laminate 3 after heating was 25.6 ppm / K, and the dielectric constant (Dk) and the dielectric loss tangent (Df) were 2.92 and 0.0028, respectively.

[0313] [Example 4]

[0314] The resin solution D for the adhesive layer was applied to the resin surface of the single-sided metal-clad laminate 1 in a dried thickness of 50 μm, and then dried at 80°C for 15 minutes, thereby producing a single-sided metal-clad laminate 4 with an adhesive layer. In addition, the single-sided metal-clad laminate 4 with an adhesive layer was evaluated after heating in an oven at 180°C for 1 minute and at 150°C for 30 minutes, and as a result, there was no problem in dimensional change, and the dielectric constant (Dk) and dielectric loss tangent (Df) were 3.00 and 0.0027, respectively.

[0315] [Example 5]

[0316] A liquid crystal polymer film (manufactured by Kuraray Co., Ltd., trade name: CT-Z, thickness: 25 μm, CTE: 18 ppm / K, heat distortion temperature: 300°C, Dk: 3.40, Df: 0.0022) was set as an insulating substrate, and a double-sided metal-clad laminate 1 having copper foils 1 provided on both surfaces thereof was prepared. The copper foil 1 on one surface of the double-sided metal-clad laminate 1 was etched and removed, thereby producing a single-sided metal-clad laminate 2.

[0317] The polyimide varnish 1 was applied to the resin surface of the single-sided metal-clad laminate 2 in a dried thickness of 50 μm, and then dried at 80°C for 15 minutes, thereby producing a single-sided metal-clad laminate 5 with an adhesive layer. In addition, the single-sided metal-clad laminate 5 with an adhesive layer was evaluated after heating in an oven at 180°C for 1 minute and at 150°C for 30 minutes, and as a result, there was no problem in dimensional change, and the dielectric constant (Dk) and dielectric loss tangent (Df) were 2.92 and 0.0026, respectively.

[0318] [Example 6]

[0319] The resin solution D for the adhesive layer was applied to the resin surface of the single-sided metal-clad laminate 2 in a dried thickness of 50 μm, and then dried at 80°C for 15 minutes, thereby producing a single-sided metal-clad laminate 6 with an adhesive layer. In addition, the single-sided metal-clad laminate 6 with an adhesive layer was evaluated after heating in an oven at 180°C for 1 minute and at 150°C for 30 minutes, and as a result, there was no problem in dimensional change, and the dielectric constant (Dk) and dielectric loss tangent (Df) were 3.00 and 0.0025, respectively.

[0320] [Example 7]

[0321] The copper foil 1 of the single-sided metal-clad laminate 1 is subjected to circuit processing using a subtractive method to produce a single-sided wiring board 1 formed with a conductor circuit layer. The copper foils 1 of the two single-sided metal-clad laminates 3 with adhesive layers are subjected to circuit processing using a subtractive method to produce two single-sided wiring boards 1 with adhesive layers formed with conductor circuit layers.

[0322] The conductor circuit layer of the single-sided wiring board 1 and the adhesive layer of one single-sided wiring board 1 with an adhesive layer, the conductor circuit layer of one single-sided wiring board 1 with an adhesive layer and the adhesive layer of the other single-sided wiring board 1 with an adhesive layer are overlapped in a respective facing manner, and then hot-press bonding is performed at 160°C and 4 MPa for 60 minutes, thereby producing a multilayer circuit board 1. In the bonded surface of the multilayer circuit board 1, the adhesive is sufficiently filled into the conductor circuit layer, and no disorder of the conductor circuit layer caused by the hot-press bonding process occurs.

[0323] [Example 8]

[0324] The two single-sided wiring boards 1 with adhesive layers are prepared, and the adhesive layer of one single-sided wiring board 1 with an adhesive layer and the adhesive layer of the other single-sided wiring board 1 with an adhesive layer are overlapped in a facing manner, and then hot-press bonding is performed at 160°C and 4 MPa for 60 minutes, thereby producing a double-sided circuit board 1. In the bonded surface of the double-sided circuit board 1, the adhesive layers are sufficiently bonded to each other, and no disorder of the conductor circuit layer caused by the hot-press bonding process occurs.

[0325] [Example 9]

[0326] The copper foils 1 of the two single-sided metal-clad laminates 4 with adhesive layers are subjected to circuit processing using a subtractive method to produce two single-sided wiring boards 2 with adhesive layers formed with conductor circuit layers.

[0327] The conductor circuit layer of the single-sided wiring board 1 and the adhesive layer of one single-sided wiring board 2 with an adhesive layer, the conductor circuit layer of one single-sided wiring board 2 with an adhesive layer and the adhesive layer of the other single-sided wiring board 2 with an adhesive layer are overlapped in a respective facing manner, and then hot-press bonding is performed at 160°C and 4 MPa for 60 minutes, thereby producing a multilayer circuit board 2. In the bonded surface of the multilayer circuit board 2, the adhesive is sufficiently filled into the conductor circuit layer, and no disorder of the conductor circuit layer caused by the hot-press bonding process occurs.

[0328] [Example 10]

[0329] Two single-sided wiring substrates 2 with adhesive layers were prepared, and the adhesive layer of one single-sided wiring substrate 2 with an adhesive layer was overlapped with the adhesive layer of the other single-sided wiring substrate 2 with an adhesive layer in a facing manner, and then heat-pressed at 160°C and 4 MPa for 60 minutes, thereby preparing a double-sided circuit substrate 2. In the pressure-bonded surface of the double-sided circuit substrate 2, the adhesive layers were sufficiently bonded to each other, and no conductor circuit disorder caused by the heat-pressing process was generated.

[0330] [Example 11]

[0331] The copper foil 1 of the single-sided metal-clad laminate 2 was subjected to circuit processing using a subtractive method, thereby preparing a single-sided wiring substrate 2 formed with a conductor circuit layer. The copper foil 1 of two single-sided metal-clad laminates 5 with adhesive layers was subjected to circuit processing using a subtractive method, thereby preparing two single-sided wiring substrates 3 with adhesive layers formed with a conductor circuit layer.

[0332] The conductor circuit layer of the single-sided wiring substrate 2 was overlapped with the adhesive layer of one single-sided wiring substrate 3 with an adhesive layer, and the conductor circuit layer of one single-sided wiring substrate 3 with an adhesive layer was overlapped with the adhesive layer of the other single-sided wiring substrate 3 with an adhesive layer in a facing manner, respectively, and then heat-pressed at 160°C and 4 MPa for 60 minutes, thereby preparing a multilayer circuit substrate 3. In the pressure-bonded surface of the multilayer circuit substrate 3, the adhesive was sufficiently filled to the conductor circuit layer, and no conductor circuit disorder caused by the heat-pressing process was generated.

[0333] [Example 12]

[0334] Two single-sided wiring substrates 3 with adhesive layers were prepared, and the adhesive layer of one single-sided wiring substrate 3 with an adhesive layer was overlapped with the adhesive layer of the other single-sided wiring substrate 3 with an adhesive layer in a facing manner, and then heat-pressed at 160°C and 4 MPa for 60 minutes, thereby preparing a double-sided circuit substrate 3. In the pressure-bonded surface of the double-sided circuit substrate 3, the adhesive layers were sufficiently bonded to each other, and no conductor circuit disorder caused by the heat-pressing process was generated.

[0335] [Example 13]

[0336] The copper foil 1 of two single-sided metal-clad laminates 6 with adhesive layers was subjected to circuit processing using a subtractive method, thereby preparing two single-sided wiring substrates 4 with adhesive layers formed with a conductor circuit layer.

[0337] The conductor circuit layer of the single-sided wiring substrate 2 and the adhesive layer of the single-sided wiring substrate 4 with an adhesive layer, the conductor circuit layer of the single-sided wiring substrate 4 with an adhesive layer and the adhesive layer of the other single-sided wiring substrate 4 with an adhesive layer were overlapped in a respective facing manner, and then heat-pressed at 160°C and 4MPa for 60 minutes, thereby producing the multilayer circuit substrate 4. In the pressure-bonded surface of the multilayer circuit substrate 4, the adhesive was sufficiently filled into the conductor circuit layer, and no disorder of the conductor circuit layer caused by the heat-pressing process was generated.

[0338] [Example 14]

[0339] Two single-sided wiring substrates 4 with an adhesive layer were prepared, and the adhesive layer of one single-sided wiring substrate 4 with an adhesive layer and the adhesive layer of the other single-sided wiring substrate 4 with an adhesive layer were overlapped in a facing manner, and then heat-pressed at 160°C and 4MPa for 60 minutes, thereby producing the double-sided circuit substrate 4. In the pressure-bonded surface of the double-sided circuit substrate 4, the adhesive layers were sufficiently bonded to each other, and no disorder of the conductor circuit layer caused by the heat-pressing process was generated.

[0340] The above-described embodiments of the present application are provided for the purpose of illustration, and the present application is not limited to the embodiments described above, and various modifications can be made.

Claims

1. A metal-clad laminate sheet comprising: an insulating resin layer; a metal layer laminated to one face of the insulating resin layer; and an adhesive layer laminated to the other face of the insulating resin layer, and the resin constituting the adhesive layer is a thermoplastic resin or a thermosetting resin, and satisfies the following conditions (i) to (iii): (i) a storage elastic modulus at 50°C is 1800 MPa or less; (ii) a maximum value of the storage elastic modulus in a temperature range from 180°C to 260°C is 800 MPa or less; (iii) a glass transition temperature is 180°C or less, the thickness T2 of the adhesive layer is in a range from 20 μm to 200 μm, the thickness T3 of the insulating resin layer is in a range from 12 μm to 100 μm, the total thickness Tl of the thickness T2 of the adhesive layer and the thickness T3 of the insulating resin layer is in a range from 50 μm to 250 μm, and the ratio (T2 / Tl) of the thickness T2 of the adhesive layer to the total thickness Tl is in a range from 0.5 to 0.

8.

2. The metal-clad laminate sheet according to claim 1, wherein the thermoplastic resin is an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue, and the adhesive polyimide contains 50 mol% or more of the diamine residue derived from a dimer acid type diamine, which is obtained by substituting both terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group, with respect to 100 mol% of the total amount of the diamine residue.

3. The metal-clad laminate sheet according to claim 1, wherein the metal-clad laminate sheet is a material of a circuit substrate in which the metal layer is processed into a wiring.

4. The metal-clad laminate sheet according to claim 2, wherein the adhesive polyimide contains 90 mol% or more of the tetracarboxylic acid residue derived from a tetracarboxylic anhydride represented by the following general formula (1) and / or general formula (2) with respect to 100 mol% of the total amount of the tetracarboxylic acid residue: in the general formula (1), X represents a single bond, or a divalent group selected from the following formulae, and in the general formula (2), the cyclic moiety represented by Y represents a cyclic saturated hydrocarbon group selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring; in the formulae, Z represents -C6H4-, -(CH2)n-, or -CH2-CH(-O-C(=O)-CH3)-CH2-, and n represents an integer from 1 to 20.

5. The metal-clad laminate sheet according to claim 2, wherein the adhesive polyimide contains 50 mol% or more and 99 mol% or less of the diamine residue derived from the dimer acid type diamine with respect to 100 mol% of the total amount of the diamine residue, and contains 1 mol% or more and 50 mol% or less of the diamine residue derived from at least one diamine compound selected from the following general formulae Bl to B7: the portion duplicated with formula B2 is removed from formula B3, and the portion duplicated with formula B4 is removed from formula B5.

6. A circuit substrate comprising: an insulating resin layer; a conductor circuit layer formed on one face of the insulating resin layer; and an adhesive layer laminated to the other face of the insulating resin layer. ​ ​ ​ ​ ​ ​ ​ ​ ​ -CO-, -SO2-, -O-, -C(CF3)2-, -COO- or -COO-Z-OCO- ​ ​ ​ In formula B1 to formula B7, R1independently represents a monovalent hydrocarbon group or alkoxy group having a carbon number of 1 to 6, the linking group A independently represents a divalent group selected from -0-, -S-, -CO-, -SO-, -S02-, -COO-, -CH2-, -C(CH3)2-, -NH-, or -CONH-, and n1independently represents an integer of 0 to 4; wherein, ​ ​ ​ ​ ​ an adhesive layer laminated to the other of the insulating resin layers, and The resin constituting the adhesive layer is a thermoplastic resin or a thermosetting resin, and satisfies the following conditions (i) to (iii): (i) a storage elastic modulus at 50°C is 1800 MPa or less; (ii) a maximum value of the storage elastic modulus in a temperature region from 180°C to 260°C is 800 MPa or less; (iii) a glass transition temperature is 180°C or less, The thickness T2 of the adhesive layer is in a range from 20 μm to 200 μm, the thickness T3 of the insulating resin layer is in a range from 12 μm to 100 μm, the total thickness Tl of the thickness T2 of the adhesive layer and the thickness T3 of the insulating resin layer is in a range from 50 μm to 250 μm, and the ratio (T2 / Tl) of the thickness T2 of the adhesive layer to the total thickness Tl is in a range from 0.5 to 0.

8.

7. The circuit substrate according to claim 6, wherein the thermoplastic resin is an adhesive polyimide containing tetracarboxylic acid residues and diamine residues, and The adhesive polyimide contains 50 mol% or more of diamine residues derived from a dimer acid type diamine, which is a dimer acid in which both terminal carboxylic acid groups are substituted with a primary aminomethyl group or an amino group, relative to 100 mol% of the total amount of the diamine residues.

8. The circuit substrate according to claim 7, characterized by: The adhesive polyimide contains 90 mol% or more of tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formula (1) and / or general formula (2) relative to 100 mol% of the total amount of the tetracarboxylic acid residues: In the general formula (1), X represents a single bond or a divalent group selected from the following formulae, and in the general formula (2), the cyclic moiety represented by Y represents a cyclic saturated hydrocarbon group selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring; -CO-, -SO2-, -O-, -C(CF3)2-, -COO- or -COO-Z-OCO- In the formulae, Z represents -C6H4-, -(CH2)n-, or -CH2-CH(-O-C(=O)-CH3)-CH2-, and n represents an integer from 1 to 20.

9. The circuit substrate according to claim 7, wherein the adhesive polyimide contains 50 mol% or more and 99 mol% or less of diamine residues derived from the dimer acid type diamine relative to 100 mol% of the total amount of the diamine residues, and contains diamine residues derived from at least one diamine compound selected from the following general formulae B1 to B7 in a range from 1 mol% or more to 50 mol% or less: In formula B1 to formula B7, R1independently represents a monovalent hydrocarbon group or alkoxy group having a carbon number of 1 to 6, the linking group A independently represents a divalent group selected from -0-, -S-, -CO-, -SO-, -S02-, -COO-, -CH2-, -C(CH3)2-, -NH-, or -CONH-, and n1independently represents an integer of 0 to 4; wherein, The portion duplicated in formula B2 is removed from formula B3, and the portion duplicated in formula B4 is removed from formula B5.

10. A multilayer circuit substrate which is a multilayer circuit substrate in which a plurality of circuit substrates are laminated, and is characterized by: at least one or more of the circuit substrate according to any one of claims 6 to 9 is included as the circuit substrate.

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