CN117794048A

CN117794048A - Metal-clad laminate, circuit board, electronic device, and electronic apparatus

Info

Publication number: CN117794048A
Application number: CN202311199034.3A
Authority: CN
Inventors: 须藤芳树; 川上翔平
Original assignee: Nippon Steel and Sumikin Chemical Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2022-09-29
Filing date: 2023-09-18
Publication date: 2024-03-29
Also published as: TW202413090A; JP2024050431A; KR20240045119A

Abstract

The invention provides a metal-clad laminate, a circuit board, an electronic device, and an electronic apparatus. In a metal-clad laminate having a laminated structure in which an adhesive layer is interposed between insulating resin layers, excellent dielectric characteristics and connection reliability after circuit processing are both achieved. The metal-clad laminate comprises: a metal layer; a first insulating resin layer laminated on at least one surface of the metal layer; a metal layer; a second insulating resin layer laminated on at least one surface of the metal layer; and an adhesive layer laminated between the first insulating resin layer and the second insulating resin layer so as to be in contact with the layers. The total thickness T1 of the resin laminate is in the range of 70-500 [ mu ] m, the ratio of the thickness T2 of the adhesive layer to the total thickness T1, namely T2/T1, is in the range of 0.10-0.96, and the adhesive layer contains (A) a thermoplastic polyimide and (B) a polystyrene elastomer having a weight average molecular weight of 100,000 or less.

Description

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

Technical Field

The present invention relates to a metal-clad laminate and a circuit board which are effectively used as electronic components, and an electronic device and an electronic apparatus using the circuit board.

Background

In recent years, along with the progress of miniaturization, weight reduction, and space saving of electronic devices, there has been an increasing demand for flexible printed wiring boards (Flexible Printed Circuits, FPC) which are thin and lightweight, have flexibility, and have excellent durability even if repeatedly bent. Since FPC can be mounted in a three-dimensional and high-density manner even in a limited space, its use is expanding in parts such as wiring, cables, connectors, etc. of electronic devices such as Hard Disk Drives (HDD), digital video discs (digital video disk, DVD), smart phones, etc. As a material of a circuit board such as FPC, a metal-clad laminate in which a metal layer and a resin layer are laminated can be used.

In addition to the higher density, the higher performance of the device is advancing, and therefore, it is also necessary to cope with the higher frequency of the transmission signal. When a high-frequency signal is transmitted, if the transmission loss in the transmission path is large, there occurs a problem such as loss of the electric signal or a longer delay time of the signal. In addition, since a mobile communication device typified by a smart phone transmits a large amount of information due to the popularization of fifth generation (5G) communication, a system is adopted in which signals of a plurality of frequency bands are transmitted simultaneously with the increase in frequency of the transmission signal. In such a metal-clad laminate for FPC for high-frequency signal transmission, it is effective to form a resin layer having a low dielectric loss tangent and a thick film from the viewpoint of improving transmission loss.

In order to cope with the high frequency of the transmission signal, a metal-clad laminate having a laminated structure in which a thick adhesive layer is interposed between insulating resin layers of a pair of single-sided metal-clad laminates has been proposed (for example, patent documents 1 and 2). Here, in patent document 1, thermoplastic polyimide using Dimer Diamine (DDA) as a raw material is used as a material of the adhesive layer. In patent document 2, a thermoplastic resin or a thermosetting resin having a specific storage elastic modulus behavior is used as a material of the adhesive layer. The thermoplastic polyimide using dimer diamine as a raw material used in patent document 1 is a resin material which is effective as an adhesive because it is soluble in a solvent, excellent in adhesion and good in handleability, but in order to cope with the progress of high frequency, further low dielectric loss tangent is required.

On the other hand, in order to improve the dielectric characteristics of the resin film, a resin film has been proposed in which a polystyrene elastomer having an acid value of 10mgKOH/g or less is blended with a thermoplastic polyimide (for example, patent document 3).

[ Prior Art literature ]

[ patent literature ]

Patent document 1 Japanese patent laid-open publication No. 2018-170417

[ patent document 2] Japanese patent laid-open No. 2020-55299

[ patent document 3] Japanese patent laid-open No. 2022-99778

Disclosure of Invention

[ problem to be solved by the invention ]

When a circuit board such as an FPC is processed using a metal-clad laminate as a material, a through hole or a through hole is formed, and then plating is performed on the inner wall of the hole. The circuit board is placed in an environment where it is repeatedly heated and cooled, for example, in a temperature range of about-65 to 125 ℃ depending on the use mode of the electronic device. Therefore, stress due to thermal expansion and contraction is concentrated in plated portions of the through holes or the through holes, and there is a problem that cracks (cracks) are generated. Such a crack causes poor conduction in the through hole or the through hole, and greatly impairs connection reliability.

In the metal-clad laminate of patent document 1 and patent document 2, handling of high-frequency signal transmission is achieved by increasing the thickness ratio of the adhesive layer having a low dielectric loss tangent, and therefore, there is a concern that connection reliability after circuit processing is easily lowered, but there is a concern that desired dielectric characteristics cannot be obtained if the thickness ratio of the adhesive layer is reduced. That is, in the metal-clad laminate having a laminated structure as in patent document 1 and patent document 2, connection reliability after circuit processing is in a trade-off relationship with improvement of dielectric characteristics. The resin film of patent document 3 has excellent dielectric characteristics, but since the weight average molecular weight of the polystyrene elastomer to be blended is large, the low dielectric loss tangent is limited, and when applied to the adhesive layer of the laminated structure as in patent document 1 and patent document 2, the thickness ratio of the adhesive layer still has to be increased, and it is difficult to ensure the connection reliability after the circuit processing, and therefore there is room for further improvement.

Accordingly, the present invention aims to: in a metal-clad laminate having a laminated structure in which an adhesive layer is interposed between insulating resin layers, excellent dielectric characteristics and connection reliability after circuit processing are both achieved.

[ means of solving the problems ]

The present inventors have made an intensive study on the material of an adhesive layer, and as a result, have found that a resin film prepared from a polystyrene elastomer having a specific molecular weight exhibits an extremely low dielectric loss tangent, and that the above-mentioned problems can be solved by applying such a resin film as an adhesive layer in a metal-clad laminate having a laminate structure in which an adhesive layer is interposed between insulating resin layers, and have completed the present invention.

That is, the metal-clad laminate of the present invention includes:

a first metal layer;

a first insulating resin layer laminated on at least one surface of the first metal layer;

a second metal layer;

a second insulating resin layer laminated on at least one surface of the second metal layer; and

and an adhesive layer laminated between the first insulating resin layer and the second insulating resin layer so as to be in contact with the layers.

In the metal-clad laminate of the present invention, the total thickness T1 of the resin laminate including the first insulating resin layer, the adhesive layer, and the second insulating resin layer is in the range of 70 μm to 500 μm, and the ratio (T2/T1) of the thickness T2 of the adhesive layer to the total thickness T1 is in the range of 0.10 to 0.96.

The adhesive layer of the metal-clad laminate of the present invention contains the following components (a) and (B);

(A) Thermoplastic polyimide,

And

(B) Polystyrene elastomer having a weight average molecular weight of 100,000 or less.

In the metal-clad laminate of the present invention, the content of the component (B) may be in the range of 10 parts by weight to 350 parts by weight with respect to 100 parts by weight of the component (a).

In the metal-clad laminate of the present invention, the dielectric loss tangent of the resin laminate at 10GHz may be 0.0030 or less, and the dielectric loss tangent of the adhesive layer at 10GHz may be less than 0.0013.

In the metal-clad laminate of the present invention, the storage modulus of elasticity of the first insulating resin layer and the second insulating resin layer at 125℃may be 1.0X10, respectively⁹Pa～8.0×10⁹Pa.

In the metal-clad laminate of the present invention, the resin laminate may have an average thermal expansion coefficient of less than 400ppm/K in the thickness direction from a reference temperature of 25 ℃ to 125 ℃.

In the metal-clad laminate of the present invention, the average thermal expansion coefficient of the resin laminate as a whole in the in-plane direction perpendicular to the thickness direction from 250 ℃ to 100 ℃ may be in the range of 10ppm/K to 30 ppm/K.

In the metal-clad laminate of the present invention, each of the first insulating resin layer and the second insulating resin layer may have a multilayer structure in which a thermoplastic polyimide layer, a non-thermoplastic polyimide layer, and a thermoplastic polyimide layer are laminated in this order,

the adhesive layer may be disposed contiguous with both of the thermoplastic polyimide layers.

The circuit board of the present invention comprises:

a first wiring layer;

a first insulating resin layer laminated on at least one surface of the first wiring layer;

a second wiring layer;

a second insulating resin layer laminated on at least one surface of the second wiring layer; and

In the circuit board of the present invention, the total thickness T1 of the resin laminate including the first insulating resin layer, the adhesive layer, and the second insulating resin layer is in the range of 70 μm to 500 μm, and the ratio (T2/T1) of the thickness T2 of the adhesive layer to the total thickness T1 is in the range of 0.10 to 0.96.

The adhesive layer of the circuit board of the present invention contains the following components (a) and (B);

(A) Thermoplastic polyimide,

And

The electronic device of the invention comprises the circuit substrate.

[ Effect of the invention ]

In the metal-clad laminate of the present invention, in the laminated structure in which the adhesive layer is interposed between the insulating resin layers, by blending the adhesive layer of the polystyrene elastomer having a specific molecular weight, even if the thickness ratio of the adhesive layer is not necessarily increased, the dielectric loss tangent of the entire resin layer can be sufficiently suppressed to be sufficiently low, and excellent dielectric characteristics and connection reliability after circuit processing can be simultaneously achieved. Therefore, the circuit board manufactured using the metal-clad laminate of the present invention can ensure conduction in the through hole or the through hole, has excellent connection reliability, and can cope with high-frequency signal transmission.

Drawings

Fig. 1 is a schematic view showing a cross-sectional structure in a thickness direction of a metal-clad laminate according to a preferred embodiment of the present invention.

[ description of symbols ]

10A, 10B: thermoplastic polyimide layer

20A, 20B: non-thermoplastic polyimide layer

30A, 30B: thermoplastic polyimide layer

40A: first insulating resin layer

40B: second insulating resin layer

100: metal-clad laminate

101: resin laminate

110A, 110B: metal layer

AD: adhesive layer

Detailed Description

Embodiments of the present invention will be described with reference to the accompanying drawings.

[ Metal-clad laminate ]

Fig. 1 shows a cross-sectional structure of a metal-clad laminate 100 according to a preferred embodiment of the present invention. The metal-clad laminate 100 includes a metal layer 110A, a first insulating resin layer 40A laminated on at least one surface of the metal layer 110A, a metal layer 110B, a second insulating resin layer 40B laminated on at least one surface of the metal layer 110B, and an adhesive layer AD laminated between these layers so as to be in contact with the first insulating resin layer 40A and the second insulating resin layer 40B. In the metal-clad laminate 100, a first insulating resin layer 40A, an adhesive layer AD, and a second insulating resin layer 40B are laminated in this order to form a resin laminate 101. Therefore, the metal-clad laminate 100 has a structure in which the metal layer 110A and the metal layer 110B are laminated on both sides of the resin laminate 101. In a preferred embodiment of the metal-clad laminate 100, the metal layers 110A and 110B are located outermost, the first insulating resin layer 40A and the second insulating resin layer 40B are disposed inside the metal layers, and the adhesive layer AD is disposed between the first insulating resin layer 40A and the second insulating resin layer 40B. The metal-clad laminate 100 having such a layer structure may be considered to have a structure in which a first single-sided metal-clad laminate in which the metal layer 110A and the first insulating resin layer 40A are laminated and a second single-sided metal-clad laminate in which the metal layer 110B and the second insulating resin layer 40B are laminated are bonded to each other with the adhesive layer AD facing each other on the insulating resin layer side.

The structure of the metal-clad laminate 100 will be specifically described below in the order of the metal layer, insulating resin layer, adhesive layer, resin laminate, and the layer thicknesses of these layers.

< Metal layer >)

The material of the metal layers 110A and 110B is not particularly limited, and examples thereof include: copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, alloys of these, and the like. Among them, copper or copper alloy is particularly preferable. The copper foil may be a rolled copper foil or an electrolytic copper foil, and commercially available copper foil may be used. The wiring layer in the circuit board according to the present embodiment described later is also made of the same material as the metal layers 110A and 110B.

The metal foil may be subjected to, for example, a rust-preventing treatment or a surface treatment with, for example, a wallboard (fixing), an aluminum alkoxide, an aluminum chelate compound, a silane coupling agent, or the like for the purpose of improving the adhesion.

< insulating resin layer >)

The resin constituting the first insulating resin layer 40A and the second insulating resin layer 40B is not particularly limited as long as it is a resin having electrical insulation properties, and examples thereof include: polyimide, epoxy, phenolic, polyethylene, polypropylene, polytetrafluoroethylene, silicone, ethylene tetrafluoroethylene (ethylene tetrafluoroethylene, ETFE), and the like, with polyimide being preferred. In the present invention, the term "polyimide" refers to a resin containing a polymer having an imide group in its molecular structure, such as polyamide imide, polyether imide, polyester imide, polysiloxane imide, and polybenzimidazole imide, in addition to polyimide.

The first insulating resin layer 40A and the second insulating resin layer 40B are not limited to a single layer, and may be formed by stacking a plurality of resin layers. Typically, fig. 1 shows the following configuration examples as a preferable example: the first insulating resin layer 40A has a three-layer laminated structure of a thermoplastic polyimide layer 10A, a non-thermoplastic polyimide layer 20A, and a thermoplastic polyimide layer 30A, and the second insulating resin layer 40B has a three-layer laminated structure of a thermoplastic polyimide layer 10B, a non-thermoplastic polyimide layer 20B, and a thermoplastic polyimide layer 30B. In this case, the metal-clad laminate 100 has a layer structure in which the metal layer 110A/thermoplastic polyimide layer 10A/non-thermoplastic polyimide layer 20A/thermoplastic polyimide layer 30A/adhesive layer AD/thermoplastic polyimide layer 30B/non-thermoplastic polyimide layer 20B/thermoplastic polyimide layer 10B/metal layer 110B are laminated in this order. Since fig. 1 is an example, the first insulating resin layer 40A and the second insulating resin layer 40B may be made of a material other than polyimide, and may have a three-layer structure, or may have a single layer, two layers, or four or more layers.

In the structural example shown in fig. 1, the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B may be made of the same or different types of thermoplastic polyimide, respectively. The non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B may be made of the same or different kinds of non-thermoplastic polyimide.

In addition, for example, a hardening resin component such as a plasticizer or an epoxy resin, a hardening agent, a hardening accelerator, an organic filler or an inorganic filler, a coupling agent, a flame retardant, or the like may be suitably blended in the first insulating resin layer 40A and the second insulating resin layer 40B.

For example, in the case of application to a circuit board, the dielectric loss tangent at 10GHz is preferably 0.02 or less, more preferably 0.0005 or more and 0.01 or less, and still more preferably 0.001 or more and 0.008 or less, in order to suppress dielectric loss. If the dielectric loss tangent at 10GHz of the first insulating resin layer 40A and the second insulating resin layer 40B exceeds 0.02, then, when applied to a circuit board, defects such as loss of an electrical signal are likely to occur in the transmission path of a high-frequency signal. The lower limit value of the dielectric loss tangent at 10GHz of the first insulating resin layer 40A and the second insulating resin layer 40B is not particularly limited, but physical property control of the circuit board as an insulating resin layer is considered.

In addition, when applied as an insulating layer of a circuit board, the first insulating resin layer 40A and the second insulating resin layer 40B preferably have a relative dielectric constant of 4.0 or less at 10GHz, respectively, in order to ensure impedance matching. If the relative dielectric constant at 10GHz of the first insulating resin layer 40A and the second insulating resin layer 40B exceeds 4.0, the dielectric loss of the first insulating resin layer 40A and the second insulating resin layer 40B increases when applied to a circuit board, and thus, there is a tendency that defects such as loss of an electrical signal are generated on a transmission path of a high-frequency signal.

The relative permittivity and dielectric loss tangent in the present invention can be measured by the methods and conditions described in examples described below.

In order to properly control the average thermal expansion coefficient in the thickness direction of the entire resin laminate 101, the storage elastic coefficients of the first insulating resin layer 40A and the second insulating resin layer 40B at 125 ℃ are preferably 1.0×10, respectively⁹Pa～8.0×10⁹Within Pa, more preferably 2.0X10⁹Pa～7.0×10⁹In the Pa range, further preferably 2.0X10⁹Pa～6.0×10⁹Pa. The storage modulus of elasticity at 125℃is less than 1.0X10⁹In Pa, physical properties such as mechanical strength required as a circuit board material may not be obtained, and in the case of using the laminate structure shown in fig. 1 in combination with an adhesive layer AD having a structure described later, it may be difficult to control the average thermal expansion coefficient in the thickness direction to a desired value. On the other hand, if the storage modulus of elasticity at 125℃exceeds 8.0X10⁹Pa may exert a large stress on surrounding wiring lines or insulating layers when the circuit board is exposed to a high-temperature environment, thereby impairing connection reliability.

Next, the non-thermoplastic polyimide layer 20A, the non-thermoplastic polyimide layer 20B, the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B constituting the first insulating resin layer 40A and the second insulating resin layer 40B will be described. In the present invention, the term "thermoplastic polyimide" is generally a polyimide whose glass transition temperature (Tg) can be clearly confirmed, and in the present invention, dynamic viscoelasticity is used The storage modulus of elasticity at 30℃measured by a measuring device (dynamic thermal mechanical analyzer (Dynamic thermomechanical analyzer, DMA)) was 1.0X10⁸A storage modulus of elasticity at 300 ℃ of less than 3.0X10 at Pa or above⁷Polyimide of Pa. In addition, the term "non-thermoplastic polyimide" is a polyimide which generally does not exhibit softening and adhesion even when heated, and in the present invention, it means that the storage modulus of elasticity at 30℃is 1.0X10 as measured by using a dynamic viscoelasticity measuring apparatus (DMA)⁹A storage elastic modulus at 300 ℃ of 3.0X10 at Pa or above⁸Polyimide of Pa or more.

Non-thermoplastic polyimide:

the polyimide used for the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B is preferably a non-thermoplastic polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride component with a diamine component containing an aliphatic diamine and/or an aromatic diamine, or the like. As the acid anhydride and the diamine, monomers generally used for the synthesis of the non-thermoplastic polyimide can be used, but the following monomers are preferable in terms of controlling the storage elastic modulus of the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B to an appropriate range. The thermal expansion, adhesion, storage modulus of elasticity, glass transition temperature, and the like can be controlled by selecting the types of the acid anhydride and the diamine, or the molar ratio of the acid anhydride or the diamine when two or more types of the acid anhydride or the diamine are used.

The non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B contains a tetracarboxylic acid residue and a diamine residue. In the present invention, the tetracarboxylic acid residue means a tetravalent group derived from tetracarboxylic dianhydride, and the diamine residue means a divalent group derived from a diamine compound. The non-thermoplastic polyimide preferably comprises an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine.

(tetracarboxylic acid residue)

The non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 20A, 20B preferably contains, as tetracarboxylic acid residues, tetracarboxylic acid residues derived from at least one of 3,3', 4' -biphenyltetracarboxylic dianhydride (3, 3', 4' -biphenyl tetracarboxylic dianhydride, BPDA) and 1, 4-phenylenebis (trimellitic acid monoester) dianhydride (1, 4-phenylenebis (trimellitic acid monoester) dianhydride, TAHQ) and from at least one of pyromellitic dianhydride (pyromellitic dianhydride, PMDA) and 2,3,6,7-naphthalene tetracarboxylic dianhydride (2, 3,6,7-naphthalene tetracarboxylic dianhydride, NTCDA).

Tetracarboxylic acid residues derived from BPDA (hereinafter also referred to as "BPDA residues") and tetracarboxylic acid residues derived from TAHQ (hereinafter also referred to as "TAHQ residues") tend to form ordered structures of polymers, and dielectric loss tangent and hygroscopicity can be reduced by suppressing molecular movement. The BPDA residue can impart self-supporting properties to a gel film of a polyamic acid as a polyimide precursor, but on the other hand, tends to be as follows: the average thermal expansion coefficient in the in-plane direction after imidization is increased, and the glass transition temperature is lowered to lower the heat resistance.

From this point of view, it is preferable to control in the following manner: the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B contains a BPDA residue and a TAHQ residue in a total of preferably 30 to 60 parts by mole, more preferably 40 to 50 parts by mole, based on 100 parts by mole of all tetracarboxylic acid residues. If the total of the BPDA residues and the TAHQ residues is less than 30 parts by mol, the ordered structure of the polymer may be insufficiently formed, the moisture absorption resistance may be lowered, or the dielectric loss tangent may be insufficiently reduced, and if it exceeds 60 parts by mol, the average thermal expansion coefficient in the in-plane direction may be increased or the heat resistance may be lowered.

Further, since tetracarboxylic acid residues derived from pyromellitic dianhydride (hereinafter, also referred to as "PMDA residues") and tetracarboxylic acid residues derived from 2,3,6, 7-naphthalene tetracarboxylic dianhydride (hereinafter, also referred to as "NTCDA residues") have rigidity, they are residues that have an effect of improving in-plane orientation, suppressing the average coefficient of thermal expansion in the in-plane direction to be low, and controlling the glass transition temperature. On the other hand, PMDA residues have a small molecular weight, and therefore if the amount thereof is too large, the imide group concentration of the polymer increases, the polar group increases, the hygroscopicity increases, and the dielectric loss tangent increases due to the influence of moisture in the molecular chain. In addition, NTCDA residues tend to have a film that is fragile and an elastic modulus that increases due to a naphthalene skeleton with high rigidity.

Accordingly, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 20A or 20B contains PMDA residues and NTCDA residues in a total of preferably 40 to 70 parts by mole, more preferably 50 to 60 parts by mole, and still more preferably 50 to 55 parts by mole, based on 100 parts by mole of all the tetracarboxylic acid residues. If the total of PMDA residues and NTCDA residues is less than 40 parts by mol, the average thermal expansion coefficient in the in-plane direction may be increased or the heat resistance may be decreased, and if it exceeds 70 parts by mol, the imide group concentration of the polymer may be increased, the polar group may be increased, the low hygroscopicity may be impaired, and the dielectric loss tangent may be increased; or the film becomes brittle and the self-supporting property of the film is lowered.

Further, the total of at least one of the BPDA residue and the TAHQ residue and at least one of the PMDA residue and the NTCDA residue is preferably 80 parts by mole or more, and more preferably 90 parts by mole or more, based on 100 parts by mole of the total tetracarboxylic acid residues.

Further, it is preferable that the molar ratio of at least one of the BPDA residue and the TAHQ residue to at least one of the PMDA residue and the NTCDA residue, { (BPDA residue+tahq residue)/(PMDA residue+ntcda residue) } is set to be in the range of 0.4 or more and 1.5 or less, preferably in the range of 0.6 or more and 1.3 or less, more preferably in the range of 0.8 or more and 1.2 or less, to control the average thermal expansion coefficient in the in-plane direction and the formation of the ordered structure of the polymer.

Since PMDA and NTCDA have rigid backbones, they can control the in-plane orientation of molecules in polyimide as compared with other general acid anhydride components, and have the effects of suppressing the average thermal expansion coefficient in the in-plane direction and increasing the glass transition temperature (Tg). Further, since the molecular weights of BPDA and TAHQ are larger than those of PMDA, the imide group concentration is reduced by an increase in the input ratio, and this has an effect on a reduction in dielectric loss tangent or a reduction in moisture absorption rate. On the other hand, when the input ratio of BPDA and TAHQ increases, the in-plane orientation of molecules in polyimide decreases, and the average thermal expansion coefficient in the in-plane direction increases. Further, the formation of an ordered structure within the molecule is advanced, and the haze value increases. From this viewpoint, the total amount of PMDA and NTCDA added is preferably in the range of 40 to 70 parts by mol, more preferably in the range of 50 to 60 parts by mol, and even more preferably in the range of 50 to 55 parts by mol, based on 100 parts by mol of the total acid anhydride component of the raw material. If the total amount of PMDA and NTCDA added is less than 40 parts by mole based on 100 parts by mole of the total acid anhydride components of the raw materials, the in-plane orientation of the molecules is reduced, and it is difficult to suppress the average thermal expansion coefficient in the in-plane direction to be low, and the heat resistance and dimensional stability of the film at the time of heating due to the reduction of Tg are reduced. On the other hand, if the total amount of PMDA and NTCDA added exceeds 70 parts by mole, the moisture absorption rate tends to increase or the elastic modulus tends to increase due to an increase in the imide group concentration.

Further, BPDA and TAHQ have effects of low dielectric loss tangent and low moisture absorption due to suppression of molecular movement or reduction of imide group concentration, but increase the average thermal expansion coefficient in the in-plane direction of the polyimide film after imidization. From this viewpoint, the total amount of BPDA and TAHQ added is preferably in the range of 30 to 60 parts by mol, more preferably in the range of 40 to 50 parts by mol, and still more preferably in the range of 40 to 45 parts by mol, based on 100 parts by mol of the total acid anhydride component of the raw material.

Examples of the tetracarboxylic acid residues other than the BPDA residues, TAHQ residues, PMDA residues, and NTCDA residues contained in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layers 20A and 20B include 3,3',4' -diphenyl sulfone tetracarboxylic dianhydride, 4' -oxydiphthalic anhydride, 2,3',3,4' -biphenyltetracarboxylic dianhydride, 2', 3' -benzophenone tetracarboxylic dianhydride, 2,3', 4' -benzophenone tetracarboxylic dianhydride or 3,3',4' -benzophenone tetracarboxylic dianhydride, 2,3',3,4' -diphenyl ether tetracarboxylic dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, 3',4' -p-terphenyl tetracarboxylic dianhydride, 2,3', 4' -para-terphenyl tetracarboxylic dianhydride or 2,2',3,3' -p-terphenyltetracarboxylic dianhydride, 2-bis (2, 3-dicarboxyphenyl) -propane dianhydride or 2, 2-bis (3, 4-dicarboxyphenyl) -propane dianhydride, bis (2, 3-dicarboxyphenyl) -methane dianhydride or bis (3, 4-dicarboxyphenyl) -methane dianhydride, bis (2, 3-dicarboxyphenyl) -sulfone dianhydride or bis (3, 4-dicarboxyphenyl) -sulfone dianhydride, 1-bis (2, 3-dicarboxyphenyl) -ethane dianhydride or 1, 1-bis (3, 4-dicarboxyphenyl) -ethane dianhydride, 1,2,7, 8-phenanthrene-tetracarboxylic dianhydride, 1,2,6, 7-phenanthrene-tetracarboxylic dianhydride or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6, 7-anthracene-tetracarboxylic dianhydride, 2, 2-bis (3, 4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5, 6-cyclohexane dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, 1,4,5, 8-naphthalene tetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic dianhydride, 2, 6-dichloro-naphthalene-1, 4,5, 8-tetracarboxylic dianhydride or 2, 7-dichloro-1, 4,5, 8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4,5, 8-) tetrachloronaphthalene-1, 4,5,8- (or 2,3,6, 7-) tetracarboxylic dianhydride, 2,3,8, 9-perylene-tetracarboxylic dianhydride aromatic tetracarboxylic acid dianhydride-derived tetracarboxylic acid residues such as 3,4,9, 10-perylene-tetracarboxylic acid dianhydride, 4,5,10, 11-perylene-tetracarboxylic acid dianhydride, or 5,6,11, 12-perylene-tetracarboxylic acid dianhydride, cyclopentane-1, 2,3, 4-tetracarboxylic acid dianhydride, pyrazine-2, 3,5, 6-tetracarboxylic acid dianhydride, pyrrolidine-2, 3,4, 5-tetracarboxylic acid dianhydride, thiophene-2, 3,4, 5-tetracarboxylic acid dianhydride, 4' -bis (2, 3-dicarboxyphenoxy) diphenylmethane dianhydride, and ethylene glycol trimellitic anhydride.

(diamine residue)

The diamine residue contained in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layers 20A and 20B is preferably a diamine residue derived from a diamine compound represented by the general formula (A1).

[ chemical 1]

In the formula (A1), is connected withThe Z radical represents a single bond or-COO-, Y independently represents a monovalent hydrocarbon group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkenyl group, which may be substituted with a halogen atom or a phenyl group, n represents an integer of 0 to 2, and p and q independently represent an integer of 0 to 4. Here, "independently" means that the plural substituents Y, and the integers p and q in the formula (A1) may be the same or different. In the formula (A1), the hydrogen atom in the terminal two amino groups may be substituted, and may be-NR₂R₃(here, R₂、R₃Independently refers to any substituent such as an alkyl group).

The diamine compound represented by the general formula (A1) (hereinafter, sometimes referred to as "diamine (A1)") is an aromatic diamine having one or more benzene rings. The diamine (A1) has a rigid structure, and thus has an effect of imparting an ordered structure to the entire polymer. Therefore, polyimide having low air permeability and low hygroscopicity can be obtained, and the moisture in the molecular chain can be reduced, so that the dielectric loss tangent can be reduced. Here, the linking group Z is preferably a single bond.

Examples of the diamine (A1) include: 1, 4-diaminobenzene (p-PDA); p-phenylenediamine), 2' -dimethyl-4,4' -diaminobiphenyl (2, 2' -dimethyl-4,4' -diaminobiphenyl, m-TB), 2' -n-propyl-4,4' -diaminobiphenyl (2, 2' -n-propyl-4,4' -diaminobiphen, m-NPB), 4-aminophenyl-4 ' -aminobenzoate (APAB), and the like.

The non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B preferably contains diamine residues derived from the diamine (A1) in an amount of preferably 80 parts by mole or more, more preferably 85 parts by mole or more, based on 100 parts by mole of the total diamine residues. By using the diamine (A1) in the amount within the above range, and by utilizing a rigid structure derived from a monomer, an ordered structure is easily formed in the whole polymer, and a non-thermoplastic polyimide having low air permeability, low hygroscopicity, and low dielectric loss tangent is easily obtained.

In the case where the diamine residue derived from the diamine (A1) is in the range of 80 to 85 parts by mole based on 100 parts by mole of the total diamine residues in the non-thermoplastic polyimide, 1, 4-diaminobenzene is preferably used as the diamine (A1) in terms of a structure that is more rigid and has excellent in-plane orientation.

Examples of the other diamine residues contained in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layers 20A and 20B include: from 2, 2-bis- [4- (3-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) biphenyl, bis [1- (3-aminophenoxy) biphenyl ] methane, bis [4- (3-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) benzophenone, 9-bis [4- (3-aminophenoxy) phenyl ] fluorene, 2-bis- [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2-bis- [4- (3-aminophenoxy) phenyl ] hexafluoropropane 3,3' -dimethyl-4, 4' -diaminobiphenyl, 4' -methylenedi-o-toluidine, 4' -methylenedi-2, 6-dimethylaniline, 4' -methylene-2, 6-diethylaniline, 3' -diaminodiphenylethane, 3' -diaminobiphenyl 3,3' -dimethoxybenzidine, 3' -diamino-p-terphenyl, 4' - [1, 4-phenylenebis (1-methylethylene) ] diphenylamine, 4' - [1, 3-phenylenebis (1-methylethylene) ] diphenylamine, bis (p-aminocyclohexyl) methane, diamine residues derived from aromatic diamine compounds such as bis (p- β -amino-tert-butylphenyl) ether, bis (p- β -methyl- δ -aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1, 1-dimethyl-5-aminopentyl) benzene, 1, 5-diaminonaphthalene, 2, 6-diaminonaphthalene, 2, 4-bis (β -amino-tert-butyl) toluene, 2, 4-diaminotoluene, m-xylene-2, 5-diamine, p-xylene-2, 5-diamine, m-xylene diamine, p-xylene diamine, 2, 6-diaminopyridine, 2, 5-diamino-1, 3, 4-oxadiazole, piperazine, 2 '-methoxy-4, 4' -diaminobenzanilide, 1, 3-bis [2- (4-aminophenyl) -2-propyl ] benzene, 6-amino-2- (4-aminophenoxy) benzoxazole; diamine residues derived from aliphatic diamine compounds such as dimer acid-type diamines in which the two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups.

In addition, since both the tetracarboxylic acid residue and the diamine residue contained in the non-thermoplastic polyimide are aromatic groups, dimensional accuracy in a high-temperature environment can be improved, and this is preferable.

The non-thermoplastic polyimide can be produced by reacting the tetracarboxylic dianhydride with a diamine compound in a solvent to produce a polyamic acid, and then heating the resultant polyamic acid to ring-close the resultant polyamic acid. For example, a polyamic acid as a precursor of polyimide is obtained by dissolving tetracarboxylic dianhydride and a diamine compound in an organic solvent in approximately equimolar amounts, and stirring the mixture at a temperature in the range of 0 to 100 ℃ for 30 minutes to 24 hours to perform polymerization. In the reaction, the reaction component is dissolved so that the precursor to be produced is in the range of 5 to 50 wt%, preferably 10 to 40 wt%, in the organic solvent. Examples of the organic solvent used in the polymerization reaction include: n, N-dimethylformamide (N, N-dimethyl formamide, DMF), N-dimethylacetamide (N, N-dimethyl acetamide, DMAc), N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethylsulfoxide (dimethyl sulfoxide, DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, cresol, and the like. These solvents may be used in combination of two or more kinds, and aromatic hydrocarbons such as xylene and toluene may be used in combination. The amount of the organic solvent used is not particularly limited, and is preferably adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight.

The synthesized polyamic acid is generally advantageously used as a reaction solvent solution, but may be concentrated, diluted, or replaced with other organic solvents as necessary. In addition, polyamide acid generally has excellent solvent solubility, so can be advantageously used. The viscosity of the solution of the polyamic acid is preferably in the range of 500 mPas to 100,000 mPas. When the thickness is outside the above range, defects such as uneven thickness and streaks are likely to occur in the film when the coating operation is performed by a coater or the like.

The method of imidizing the polyamic acid to form a non-thermoplastic polyimide is not particularly limited, and for example, the following heat treatment can be preferably employed: heating is performed in the solvent at a temperature ranging from 80 ℃ to 400 ℃ for 1 hour to 24 hours.

The weight average molecular weight of the non-thermoplastic polyimide is, for example, preferably in the range of 10,000 ～ 400,000, more preferably in the range of 50,000 ～ 350,000. If the weight average molecular weight is less than 10,000, the strength of the film tends to be low and embrittlement tends to occur. On the other hand, if the weight average molecular weight exceeds 400,000, the viscosity tends to excessively increase, and defects such as uneven film thickness and streaks tend to occur during the coating operation.

From the viewpoint of heat resistance, the glass transition temperature (Tg) of the non-thermoplastic polyimide layer 20A or the non-thermoplastic polyimide layer 20B is preferably 280 ℃ or higher, and more preferably 300 ℃ or higher.

In addition, from the viewpoint of suppressing warpage, the average thermal expansion coefficient in the in-plane direction perpendicular to the thickness direction of the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B is preferably in the range of from 250 ℃ to 100 ℃, more preferably in the range of from 1ppm/K to 30ppm/K, still more preferably in the range of from 1ppm/K to 25ppm/K, still more preferably in the range of from 15ppm/K to 25 ppm/K.

In addition, for example, other curing resin components such as plasticizers and epoxy resins, curing agents, curing accelerators, coupling agents, fillers, flame retardants, and the like may be suitably blended as optional components in the non-thermoplastic polyimide used for the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B.

Thermoplastic polyimide:

the polyimide used for the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B is preferably a thermoplastic polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic acid anhydride component with an aliphatic diamine and/or an aromatic diamine. As the acid anhydride and the diamine, monomers generally used for synthesis of thermoplastic polyimide can be used, but the following monomers are preferable in terms of controlling the storage elastic modulus of the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B to an appropriate range. The thermal expansion, adhesion, storage modulus of elasticity, glass transition temperature, and the like can be controlled by selecting the types of the acid anhydride and the diamine, or the molar ratio of the acid anhydride or the diamine when two or more types of the acid anhydride or the diamine are used. In addition, from the viewpoint of improving dielectric characteristics, as the polyimide used for the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B, it is also preferable to use a thermoplastic polyimide as the component (a) for forming the adhesive layer AD.

The thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, and 30B contains a tetracarboxylic acid residue and a diamine residue, and preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine.

(tetracarboxylic acid residue)

The tetracarboxylic acid residue used in the thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, and 30B may be the same as that exemplified as the tetracarboxylic acid residue in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layers 20A and 20B.

(diamine residue)

The diamine residues contained in the thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, and 30B are preferably diamine residues derived from diamine compounds represented by the general formulae (B1) to (B7).

[ chemical 2]

In the formulae (B1) to (B7), R₁Independently represents a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group, the linking groups A independently represent a member selected from the group consisting of-O-; -S-, -CO-, -SO ₂-、-COO-、-CH₂-、-C(CH₃)₂Divalent radical in-NH-or-CONH-, n₁Independently represents an integer of 0 to 4. Wherein the part repeating the formula (B2) is removed from the formula (B3), and the part repeating the formula (B4) is removed from the formula (B5). The term "independently" as used herein means one or more of the above formulae (B1) to (B7) include a plurality of linking groups A and a plurality of R₁Or a plurality of n₁May be the same or different. In the formulae (B1) to (B7), the hydrogen atom in the terminal two amino groups may be substituted, and may be-NR₂R₃(here, R₂、R₃Independently refers to any substituent such as an alkyl group).

The diamine represented by the formula (B1) (hereinafter, sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. The diamine (B1) is considered to have an increased degree of freedom and high flexibility in the polyimide molecular chain, which contributes to an improvement in flexibility of the polyimide molecular chain, by having an amino group directly bonded to at least one benzene ring and a divalent linking group a in the meta position. Therefore, by using the diamine (B1), the thermoplastic properties of the polyimide are improved. Here, the linking group A is preferably-O-, -CH₂-、-C(CH₃)₂-、-CO-、-SO₂-、-S-、-COO-。

Examples of the diamine (B1) include: 3,3' -diaminodiphenylmethane, 3' -diaminodiphenylpropane, 3' -diaminodiphenylsulfide, 3' -diaminodiphenylsulfone, 3' -diaminodiphenylether, 3,4' -diaminodiphenylether 3,4' -diaminodiphenylmethane, 3,4' -diaminodiphenylpropane, 3,4' -diaminodiphenylsulfide, 3' -diaminobenzophenone, (3, 3' -diamino) diphenylamine, and the like.

The diamine represented by the formula (B2) (hereinafter, sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. The diamine (B2) is considered to have an increased degree of freedom and high flexibility in the polyimide molecular chain, which contributes to an improvement in flexibility of the polyimide molecular chain, by having an amino group directly bonded to at least one benzene ring and a divalent linking group a in the meta position. Therefore, by using the diamine (B2), the thermoplastic properties of the polyimide are improved. Here, the linking group A is preferably-O-.

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

The diamine represented by the formula (B3) (hereinafter, sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. The diamine (B3) is considered to have a high flexibility and an increased degree of freedom in the polyimide molecular chain by the two divalent linking groups a directly bonded to one benzene ring being in the meta position with respect to each other, and contributes to an improvement in the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B3), the thermoplastic properties of the polyimide are improved. Here, the linking group A is preferably-O-.

Examples of the diamine (B3) include: 1,3-bis (4-aminophenoxy) benzene (1, 3-bis (4-aminophenoxy) benzene, TPE-R), 1,3-bis (3-aminophenoxy) benzene (1, 3-bis (3-aminophenoxy) benzene, APB), 4' - [ 2-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 4' - [ 4-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 4' - [ 5-methyl- (1, 3-phenylene) dioxy ] diphenylamine, and the like.

The diamine represented by the formula (B4) (hereinafter, sometimes referred to as "diamine (B4)") is an aromatic diamine having four benzene rings. The diamine (B4) is considered to have high flexibility by having an amino group directly bonded to at least one benzene ring and a divalent linking group a in a meta position, and contributes to improvement of flexibility of a polyimide molecular chain. Therefore, by using the diamine (B4), the thermoplastic properties of the polyimide are improved. Here, the linking group A is preferably-O-, -CH₂-、-C(CH₃)₂-、-SO₂-、-CO-、-CONH-。

The diamine (B4) includes: 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) ] benzanilide, and the like.

The diamine represented by the formula (B5) (hereinafter, sometimes referred to as "diamine (B5)") is an aromatic diamine having four benzene rings. The diamine (B5) is considered to have an increased degree of freedom and a high flexibility in the polyimide molecular chain by the two divalent linking groups a directly bonded to at least one benzene ring being in the meta position with respect to each other, contributing to the improvement of the flexibility of the polyimide molecular chain. Therefore, by using the diamine (B5), the thermoplastic properties of the polyimide are improved. Here, the linking group A is preferably-O-.

Examples of the diamine (B5) include 4- [3- [4- (4-aminophenoxy) phenoxy ] aniline and 4,4' - [ oxybis (3, 1-phenylene) oxy) ] diphenylamine.

The diamine represented by the formula (B6) (hereinafter, sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. The diamine (B6) is considered to have high flexibility by having at least two ether bonds, which contributes to the improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (B6), the thermoplastic properties of the polyimide are improved. Here, as the linking group A, it is preferably-C (CH)₃)₂-、-O-、-SO₂-、-CO-。

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

The diamine represented by the formula (B7) (hereinafter, sometimes referred to as "diamine (B7)") is an aromatic diamine having four benzene rings. The diamine (B7) has a divalent linking group a having high flexibility on both sides of the diphenyl skeleton, and thus is considered to contribute to the improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (B7), the thermoplastic properties of the polyimide are improved. Here, the linking group A is preferably-O-.

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

The thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, and 30B preferably contains diamine residues derived from at least one diamine compound selected from the group consisting of diamines (B1) to (B7) in a range of 60 parts by mole or more, preferably 60 parts by mole or more and 99 parts by mole or less, more preferably 70 parts by mole or more and 95 parts by mole or less, relative to 100 parts by mole of the total diamine residues. Since the diamines (B1) to (B7) contain a molecular structure having flexibility, the use of at least one diamine compound selected from these in the above-described amount can improve the flexibility of the polyimide molecular chain and impart thermoplasticity. If the total amount of the diamines (B1) to (B7) in the raw material is less than 60 parts by mole based on 100 parts by mole of the total diamine components, sufficient thermoplasticity cannot be obtained due to insufficient flexibility of the polyimide resin.

The diamine residues contained in the thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, and 30B are preferably diamine residues derived from the diamine compound represented by the general formula (A1). The diamine compound [ diamine (A1) ] represented by the formula (A1) is as described in the description of the non-thermoplastic polyimide. The diamine (A1) has a rigid structure and has an effect of imparting an ordered structure to the whole polymer, and thus can reduce dielectric loss tangent or hygroscopicity by suppressing movement of molecules. Further, when the polyimide is used as a raw material for a thermoplastic polyimide, a polyimide having low air permeability and excellent heat adhesion resistance over a long period of time can be obtained.

The thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, 30B may contain a diamine residue derived from the diamine (A1) in a range of preferably 1 to 40 parts by mole, more preferably 5 to 30 parts by mole. By using the diamine (A1) in the above-described amount, and by utilizing the rigid structure derived from the monomer, an ordered structure is formed in the whole polymer, and thus a polyimide which is thermoplastic, low in air permeability and hygroscopicity, and excellent in heat adhesion resistance over a long period of time can be obtained.

The thermoplastic polyimide constituting the thermoplastic polyimide layers 10A, 10B, 30A, 30B may contain a diamine residue derived from a diamine compound other than the diamine (A1), the diamine (B1) to the diamine (B7) within a range that does not impair the effects of the present invention.

The thermal expansion coefficient, the tensile modulus of elasticity, the glass transition temperature, and the like can be controlled by selecting the types of the tetracarboxylic acid residue and the diamine residue in the thermoplastic polyimide, or by using the molar ratio of each of two or more types of the tetracarboxylic acid residue and the diamine residue. In the case where the thermoplastic polyimide has a plurality of polyimide structural units, the polyimide structural units may exist in the form of blocks or may exist randomly, but are preferably randomly present.

In addition, by setting both the tetracarboxylic acid residue and the diamine residue contained in the thermoplastic polyimide as aromatic groups, dimensional accuracy in a high-temperature environment can be improved.

The synthesis of the thermoplastic polyimide and the precursor thereof can be performed in the same manner as the non-thermoplastic polyimide.

The weight average molecular weight of the thermoplastic polyimide is, for example, preferably in the range of 10,000 ～ 400,000, more preferably in the range of 50,000 ～ 350,000. If the weight average molecular weight is less than 10,000, the strength of the film tends to be low and embrittlement tends to occur. On the other hand, if the weight average molecular weight exceeds 400,000, the viscosity tends to excessively increase, and defects such as uneven film thickness and streaks tend to occur during the coating operation.

In the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B, the glass transition temperature (Tg) is preferably in the range of 150 ℃ or more and less than 300 ℃, more preferably 200 ℃ to 290 ℃, and most preferably 200 ℃ to 280 ℃ from the viewpoint of exhibiting adhesion to a metal foil or other insulating layer material.

In view of suppressing warpage, the thermoplastic polyimide layers 10A, 10B, 30A, and 30B preferably have an average thermal expansion coefficient of 30ppm/K or more, preferably in the range of 30ppm/K or more and 100ppm/K or less, more preferably in the range of 30ppm/K or more and 80ppm/K or less, from 250 ℃ to 100 ℃ in the in-plane direction perpendicular to the thickness direction.

In addition, in addition to the polyimide, other curing resin components such as plasticizers and epoxy resins, curing agents, curing accelerators, inorganic fillers, coupling agents, fillers, flame retardants, and the like may be suitably blended as optional components in the resins used for the thermoplastic polyimide layers 10A, 10B, 30A, and 30B.

< adhesion layer >)

The adhesive layer AD contains the following component (a) and component (B);

(A) Thermoplastic polyimide,

And

(A) The components are as follows:

(A) The component (a) is thermoplastic polyimide with adhesiveness. The thermoplastic polyimide as the component (a) is obtained by imidizing a polyamic acid which is a precursor obtained by reacting a tetracarboxylic anhydride component with a diamine component, and is solvent-soluble. The thermoplastic polyimide as the component (A) contains a tetracarboxylic acid residue derived from a tetracarboxylic anhydride and a diamine residue derived from a diamine compound.

(tetracarboxylic acid residue)

The thermoplastic polyimide as the component (a) may contain, without particular limitation, tetracarboxylic acid residues derived from tetracarboxylic acid anhydride generally used in thermoplastic polyimide, but preferably contains 90 parts by mole or more in total of tetracarboxylic acid residues derived from tetracarboxylic acid anhydride represented by the following general formula (1) (hereinafter, sometimes referred to as "tetracarboxylic acid residue (1)") per 100 parts by mole of the total of the tetracarboxylic acid residues. It is preferable that the thermoplastic polyimide as the component (A) has flexibility and heat resistance, because it is easy to achieve both the flexibility and heat resistance by containing 90 parts by mole or more of the tetracarboxylic acid residues (1) in total with respect to 100 parts by mole of the total of the tetracarboxylic acid residues. When the total amount of the tetracarboxylic acid residues (1) is less than 90 parts by mole, the solvent solubility of the thermoplastic polyimide as the component (A) tends to be lowered.

[ chemical 3]

In the general formula (1), X represents a single bond or a divalent group selected from the following formulas.

[ chemical 4]

In the formula, Z represents-C₆H₄-、-(CH₂) n-or-CH₂-CH(-O-C(＝O)-CH₃)-CH₂-n represents an integer from 1 to 20.

Examples of the tetracarboxylic dianhydride used for deriving the tetracarboxylic acid residue (1) include: 3,3',4' -biphenyltetracarboxylic dianhydride (3, 3',4' -biphenyl tetracarboxylic dianhydride, BPDA), 3',4' -benzophenone tetracarboxylic dianhydride (3, 3',4,4' -benzophenone tetracarboxylic dianhydride, BTDA), 3',4' -diphenyl sulfone tetracarboxylic dianhydride (3, 3',4,4' -diphenylsulfone tetracarboxylic dianhydride, DSDA), 4'-oxydiphthalic anhydride (4, 4' -oxydiphthalic dianhydride, ODPA), 4'- (hexafluoroisopropylidene) diphthalic anhydride (4, 4' - (hexafluorooisopropylidene) diphthalic anhydride,6 FDA), 2-bis [ 4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride (2, 2-bis [ 4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, BPADA), p-phenylene bis (trimellitic acid monoester anhydride) (p-phenyl bis (trimellitic acid monoester anhydride), TAHQ), ethylene glycol bis trimellitic anhydride (ethylene glycol bistrimellitic anhydride, TMEG), and the like.

The thermoplastic polyimide as the component (A) may contain a tetracarboxylic acid residue derived from an acid anhydride other than the tetracarboxylic acid anhydride represented by the general formula (1) within a range that does not impair the effect of the invention. The tetracarboxylic acid residue is not particularly limited, and examples thereof include pyromellitic dianhydride, 1, 4-phenylene bis (trimellitic acid monoester) dianhydride, 2,3',3,4' -biphenyl tetracarboxylic acid dianhydride, 2', 3' -benzophenone tetracarboxylic acid dianhydride, and 2,3', 4' -benzophenone tetracarboxylic dianhydride, 2,3',3,4' -diphenyl ether tetracarboxylic dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, 3",4" -p-terphenyl tetracarboxylic dianhydride, 2, 3",4" -p-terphenyl tetracarboxylic dianhydride or 2,2",3, 3' -p-terphenyltetracarboxylic dianhydride, 2-bis (2, 3-dicarboxyphenyl) -propane dianhydride or 2,2-bis (3, 4-dicarboxyphenyl) -propane dianhydride, bis (2, 3-dicarboxyphenyl) -methane dianhydride or bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) sulfone dianhydride or bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride or 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1,2,7, 8-phenanthrene-tetracarboxylic dianhydride, 1,2,6, 7-phenanthrene-tetracarboxylic dianhydride or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6, 7-anthracene-tetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5, 6-cyclohexane dianhydride, 1,2,5, 6-naphthalene-dicarboxylic anhydride, 4-tetracarboxylic dianhydride, 4, 8-naphthalene-tetracarboxylic dianhydride, 3, 8-naphthalene-tetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic dianhydride, 2, 6-dichloro-naphthalene-1, 4,5, 8-tetracarboxylic dianhydride or 2, 7-dichloro-naphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4,5, 8-) tetrachloronaphthalene-1, 4,5,8- (or 2,3,6, 7-) tetracarboxylic dianhydride, 2,3,8, 9-perylene-tetracarboxylic dianhydride, 3,4,9, 10-perylene-tetracarboxylic dianhydride, 4,5,10, 11-perylene-tetracarboxylic dianhydride or 5,6,11, 12-perylene-tetracarboxylic dianhydride, cyclopentane-1, 2,3, 4-tetracarboxylic dianhydride, pyrazine-2, 3,5, 6-tetracarboxylic dianhydride, pyrrolidine-2, 3,4, 5-tetracarboxylic dianhydride, thiophene-2, 4 '-tetracarboxylic dianhydride, 4' -4-tetraphenyl dicarboxylic dianhydride, and the like.

(diamine residue)

The thermoplastic polyimide as the component (a) preferably contains 20 parts by mole or more, preferably 40 parts by mole or more, more preferably 60 parts by mole or more of a diamine residue derived from a dimer diamine composition (hereinafter, sometimes referred to as "dimer acid-type diamine residue") containing a dimer diamine in which two terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups, as a main component, relative to 100 parts by mole of the total diamine residues. By containing the dimer acid-based diamine residue in the above amount, the dielectric characteristics of the adhesive layer AD can be improved, and the thermocompression bonding characteristics can be improved by lowering the glass transition temperature (lowering Tg) of the adhesive layer AD, and the internal stress can be relaxed by lowering the elastic modulus. If the dimer acid-based diamine residues are less than 20 parts by mole per 100 parts by mole of the total diamine residues, sufficient adhesion may not be obtained as the adhesive layer AD interposed between the first insulating resin layer 40A and the second insulating resin layer 40B, and the adhesive layer AD having high thermal expansion may have a high elastic modulus and may have impaired dimensional stability.

The dimer diamine composition is a mixture containing the following component (a) as a main component, and may contain the component (b) and the component (c), and is a purified product in which the amounts of the component (b) and the component (c) are controlled.

(a) Dimer diamine

(b) Monoamine compound obtained by substituting terminal carboxylic acid group of monoacid compound having 10-40 carbon atoms with primary aminomethyl group or amino group

(c) Amine compound obtained by substituting terminal carboxylic acid group of polybasic acid compound having hydrocarbon group in the range of 41 to 80 carbon atoms with primary aminomethyl group or amino group (wherein the dimer diamine is excluded)

The dimer diamine as component (a) means that the two terminal carboxylic acid groups (-COOH) of dimer acid are substituted with primary aminomethyl groups (-CH)₂-NH₂) Or amino (-NH)₂) And (3) diamine. Dimer acids are known dibasic acids obtained by intermolecular polymerization of unsaturated fatty acidsThe industrial production process is generally standardized in the industry, and the process can be obtained by dimerization of 11 to 22 carbon-containing unsaturated fatty acids using a clay catalyst or the like. The dimer acid obtained industrially contains, as a main component, a dibasic acid having 36 carbon atoms obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid, linoleic acid, linolenic acid, etc., and, depending on the degree of purification, any amount of a monomer acid (having 18 carbon atoms), a trimer acid (having 54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. In addition, although double bonds remain after the dimerization reaction, in the present invention, the dimer acid also contains a compound which further undergoes hydrogenation reaction to reduce the degree of unsaturation. The dimer diamine as the component (a) may be defined as a diamine compound obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having a carbon number in the range of 18 to 54, preferably 22 to 44, with a primary aminomethyl group or an amino group.

As a feature of the dimer diamine, a characteristic of a skeleton derived from dimer acid may be imparted. That is, since dimer diamine is an aliphatic group of a large molecule having a molecular weight of about 560 to 620, the molar volume of the molecule can be increased and the polar groups of polyimide can be relatively reduced. The characteristic of such dimer diamine is considered to contribute to suppression of a decrease in heat resistance of polyimide, and improvement in dielectric characteristics by reduction in relative permittivity and dielectric loss tangent. Further, since the polyimide contains two hydrophobic chains having 7 to 9 carbon atoms which are free to move and two chain aliphatic amino groups having a length close to 18 carbon atoms, it is considered that the polyimide can be provided with flexibility and can have an asymmetric chemical structure or a nonplanar chemical structure, and thus the dielectric constant of the polyimide can be reduced.

The following dimer diamine compositions are preferably used: the dimer diamine content as the component (a) is increased to 96% by weight or more, preferably 97% by weight or more, more preferably 98% by weight or more by a purification method such as molecular distillation. By setting the dimer diamine content as the component (a) to 96% by weight or more, the molecular weight distribution of the polyimide can be suppressed from expanding. If technically feasible, the dimer diamine composition is preferably composed of the dimer diamine as component (a) in its entirety (100 wt%).

The dimer diamine composition preferably has a total of the component (b) and the component (c) of 4% or less, preferably less than 4%, in terms of the area percentage of the chromatogram obtained by measurement by gel permeation chromatography (gel permeation chromatography, GPC). The area percentage of the chromatogram of the component (b) is preferably 3% or less, more preferably 2% or less, and further preferably 1% or less, and the area percentage of the chromatogram of the component (c) is preferably 2% or less, more preferably 1.8% or less, and further preferably 1.5% or less. By setting the range, a rapid increase in the molecular weight of polyimide can be suppressed, and further, an increase in the dielectric loss tangent of the resin film at a wide frequency can be suppressed. The component (b) and the component (c) may not be contained in the dimer diamine composition.

Examples of the dimer diamine composition include a commercially available product such as Pr Li Amin (PRIAMINE) 1073 (trade name) manufactured by Croda Japan (Croda Japan), pr Li Amin (PRIAMINE) 1074 (trade name) manufactured by Croda Japan (Croda Japan), and Pr Li Amin (PRIAMINE) 1075 (trade name) manufactured by Croda Japan (Croda Japan). In the case of using these commercial products, it is preferable to perform the purification for the purpose of reducing the content of components other than dimer diamine, and for example, it is preferable to set the content of dimer diamine to 96% by weight or more. The purification method is not particularly limited, and conventional methods such as distillation and precipitation purification are preferable.

The thermoplastic polyimide as the component (a) preferably contains a diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the general formulae (B1) to (B7) in a range of 20 to 80 parts by mole based on 100 parts by mole of the total of all diamine residues, more preferably contains a diamine residue in a range of 20 to 60 parts by mole. Since the diamine compounds represented by the general formulae (B1) to (B7) contain a molecular structure having flexibility, the flexibility of the polyimide molecular chain can be improved and the thermoplastic properties can be imparted by using at least one diamine compound selected from these compounds in the above-mentioned amounts. If the total amount of the residues derived from the diamine compounds represented by the general formulae (B1) to (B7) exceeds 80 parts by mole based on 100 parts by mole of all diamine residues, the polyimide may have insufficient flexibility and may have an increased Tg, and thus the residual stress due to thermocompression bonding may be increased and the dimensional stability may be impaired.

The thermoplastic polyimide as the component (a) may contain the dimer acid-based diamine residue and a diamine residue other than the diamine residues derived from the diamines (B1) to (B7) within a range that does not impair the effects of the invention. As such a diamine residue, a diamine compound generally used as a thermoplastic polyimide can be used without limitation.

The average thermal expansion coefficient, storage modulus of elasticity, glass transition temperature, and the like of the adhesive layer AD can be controlled by selecting the types of the tetracarboxylic acid residue and the diamine residue in the thermoplastic polyimide as the component (a), or by using the respective molar ratios of two or more types of the tetracarboxylic acid residue and the diamine residue. In the thermoplastic polyimide as the component (a), when the polyimide has a plurality of structural units of polyimide, the thermoplastic polyimide may exist in the form of blocks or may exist randomly, but is preferably randomly.

The synthesis of the thermoplastic polyimide and the precursor thereof as the component (a) can be performed in the same manner as the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B, or the thermoplastic polyimide constituting the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B.

The weight average molecular weight of the thermoplastic polyimide as the component (a) is, for example, preferably in the range of 10,000 ～ 400,000, more preferably in the range of 20,000 ～ 350,000. If the weight average molecular weight is less than 10,000, the strength of the adhesive layer AD tends to be low, and embrittlement tends to occur. On the other hand, if the weight average molecular weight exceeds 400,000, the viscosity tends to excessively increase, and defects such as uneven thickness and streaks of the adhesive layer AD tend to occur during the coating operation.

The thermoplastic polyimide as the component (A) is most preferably a structure after complete imidization. Among them, a part of polyimide may be amic acid. The imidization ratio was measured by using a Fourier transform infrared spectrophotometer (commercially available product: FT/IR620 manufactured by Japanese Spectroscopy) and measuring the infrared absorption spectrum of a polyimide film by a primary reflection ATR method, at 1015cm^-1Based on the nearby benzene ring absorber, according to 1780cm^-1C=o from imide groups.

(B) The components are as follows:

the polystyrene elastomer as the component (B) is a copolymer of styrene or a derivative thereof and a conjugated diene compound, and contains a hydride thereof. Here, styrene or its derivative is not particularly limited, and examples thereof may be given: styrene, methyl styrene, butyl styrene, divinylbenzene, vinyl toluene, and the like. The conjugated diene compound is not particularly limited, and examples thereof include: butadiene, isoprene, 1, 3-pentadiene, and the like.

In addition, the polystyrene elastomer is preferably hydrogenated. By hydrogenation, thermal stability is further improved, degradation such as decomposition and polymerization is less likely to occur, and aliphatic properties are improved, so that compatibility with the thermoplastic polyimide as the component (a) is improved.

The copolymer structure of the polystyrene elastomer as the component (B) may have a block structure or a random structure. Preferable specific examples of the polystyrene elastomer include: styrene-butadiene-styrene block copolymers (SBS), styrene-butadiene-butylene-styrene block copolymers (SBBS), styrene-ethylene-butylene-styrene block copolymers (SEBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), styrene-ethylene-ethylene/propylene-styrene block copolymers (SEEPS), and the like, but are not limited to these specific examples.

The polystyrene elastomer as the component (B) has a weight average molecular weight of 100,000 or less, preferably in the range of 50,000 ～ 100,000, more preferably in the range of 70,000 ～ 100,000. By the weight average molecular weight of the polystyrene elastomer being 100,000 or less, the component (B) can be relatively blended in a large amount with respect to the component (a), and the dielectric characteristics of the adhesive layer AD can be greatly improved. Specifically, even if the component (B) is blended at a high concentration in the range of 76 to 250 parts by weight relative to 100 parts by weight of the component (a), for example, the increase in viscosity of the resin composition containing the component (a) can be suppressed, and the effect of reducing the dielectric loss tangent by blending the polystyrene elastomer can be exhibited to the maximum.

On the other hand, if the weight average molecular weight of the polystyrene elastomer exceeds 100,000 and becomes too large, the viscosity of the resin composition becomes high when it is mixed with the component (a), and thus the production of the resin film may become difficult, and as a result, the blending amount of the component (B) is restricted, and thus it is difficult to reduce the dielectric loss tangent at 10GHz of the adhesive layer AD to less than 0.0020.

The acid value of the polystyrene elastomer as the component (B) is, for example, preferably 10mgKOH/g or less, more preferably 1mgKOH/g or less, and still more preferably 0mgKOH/g. By blending a polystyrene elastomer having an acid value of 10mgKOH/g or less into the thermoplastic polyimide as the component (A), the dielectric loss tangent at the time of forming the adhesive layer AD can be reduced, and good peel strength can be maintained. On the other hand, if the acid value exceeds 10mgKOH/g, the dielectric properties become poor and the compatibility with component (A) becomes poor due to the increase of the polar groups, and the adhesion at the time of forming the adhesive layer AD is lowered. Therefore, as the acid value is lower, the material which is not acid-modified (i.e., the material having an acid value of 0 mgKOH/g) is most suitable as the component (B) of the present invention. In the present invention, since the thermoplastic polyimide as the component (a) can exhibit excellent adhesion when it contains a residue derived from an aliphatic diamine, even if a polystyrene elastomer which has not been acid-modified (i.e., has a strong aliphatic property) is used, a decrease in adhesion strength can be avoided.

Styrene unit [ -CH ] in the polystyrene elastomer as component (B)₂CH(C₆H₅)-]The content ratio of (2) is preferably in the range of 10% by weight or more and 65% by weight or less, more preferably in the range of 20% by weight or more and 65% by weight or less, and most preferably in the range of 30% by weight or more and 60% by weight or less. If the content of the styrene unit in the polystyrene elastomer is less than 10% by weight, the elastic modulus of the resin is lowered, and if the content is higher than 65% by weight, the resin becomes rigid and difficult to use as an adhesive, and besides, the rubber component in the polystyrene elastomer is reduced, resulting in deterioration of the dielectric characteristics.

Further, since the content ratio of the styrene unit is within the above range, the proportion of the aromatic ring in the adhesive layer AD increases, and therefore, when the through hole (through hole) and the blind hole are formed by laser processing in the process of manufacturing the circuit board using the adhesive layer AD, the absorptivity in the ultraviolet region can be improved, and the laser processability can be further improved.

The polystyrene elastomer as the component (B) may be selected from commercially available ones. As such a commercially available polystyrene elastomer, for example, MD1653MO (trade name), G1653VO (trade name), G1726VS (trade name) and the like manufactured by KRATON are preferably used.

In the adhesive layer AD, when the thermoplastic polyimide as the component (a) has a ketone group, the ketone group is reacted with an amino group of an amino compound having at least two primary amino groups as functional groups to form a c=n bond, whereby a crosslinked structure can be formed. By forming a crosslinked structure, the heat resistance of the thermoplastic polyimide as the component (a) can be improved. As the tetracarboxylic anhydride preferable for forming the thermoplastic polyimide as the component (A) having a ketone group, for example, 3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) is exemplified, and as the diamine compound, for example, aromatic diamines such as 4,4' -bis (3-aminophenoxy) benzophenone (BABP), 1,3-bis [4- (3-aminophenoxy) benzoyl ] benzene (1, 3-bis [4- (3-aminophenoxy) benzoyl ] benzene, BABB) and the like are exemplified.

Examples of the amino compound that can be used for crosslinking of the thermoplastic polyimide as the component (a) include: dihydrazide compounds, aromatic diamines, aliphatic amines, and the like. Among these, dihydrazide compounds are preferable. Aliphatic amines other than dihydrazide compounds tend to form crosslinked structures even at room temperature, and there is concern about storage stability of varnishes, while aromatic diamines need to be set at high temperatures in order to form crosslinked structures. When the dihydrazide compound is used, both the storage stability of the varnish and the shortening of the curing time can be achieved. Examples of the dihydrazide compound include 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-naphthoic acid dihydrazide, 4-bisphenyldihydrazide, 1, 4-naphthoic acid dihydrazide, 2, 6-pyridine dihydrazide, itaconic acid dihydrazide and the like. The dihydrazide compounds mentioned above may be used alone or in combination of two or more.

When the thermoplastic polyimide as the component (a) is crosslinked, the amino compound is added to a resin solution containing the thermoplastic polyimide as the component (a) having a ketone group, and the ketone group in the thermoplastic polyimide as the component (a) and the primary amino group of the amino compound undergo a condensation reaction. The resin solution is cured by the condensation reaction to form a cured product. In this case, the amino compound may be added in such a manner that the total amount of the primary amino groups is 0.004 to 1.5 mol, preferably 0.005 to 1.2 mol, more preferably 0.03 to 0.9 mol, and most preferably 0.04 to 0.5 mol, based on 1 mol of the ketone group. When the total amount of the amino compounds is less than 0.004 mole based on 1 mole of the ketone group, the thermoplastic polyimide as the component (a) is not sufficiently crosslinked by the amino compounds, and therefore the heat resistance tends to be hardly exhibited in the adhesive layer AD after curing, and when the amount of the amino compounds exceeds 1.5 mole, the unreacted amino compounds act as a thermoplastic agent, and the heat resistance of the adhesive layer AD tends to be lowered.

The conditions for the condensation reaction for crosslinking are not particularly limited as long as the ketone group in the thermoplastic polyimide as the component (a) reacts with the primary amino group of the amino compound to form an imine bond (c=n bond). The temperature of the thermal condensation is preferably in the range of 120 to 220 ℃, more preferably in the range of 140 to 200 ℃ for the reason that the condensation step is simplified, for example, by discharging water generated by condensation out of the system or by performing the thermal condensation reaction after the synthesis of the thermoplastic polyimide as the component (a). The reaction time is preferably about 30 minutes to 24 hours, and the end point of the reaction can be measured by, for example, infrared absorption spectroscopy using a Fourier transform infrared spectrophotometer (commercially available product: FT/IR620 manufactured by Japanese Spectroscopy), and using 1670cm^-1Near absorption peak reduction or disappearance of ketone group derived from polyimide resin and 1635cm^-1The occurrence of a nearby imide-derived absorption peak was confirmed.

The thermal condensation of the ketone group of the thermoplastic polyimide as the component (a) with the primary amino group of the amino compound can be carried out, for example, by the following method: the resin composition containing the thermoplastic polyimide as the component (a), the polystyrene elastomer as the component (B), and the amino compound is processed into a predetermined shape and then heated (for example, after being applied to an arbitrary substrate or formed into a film shape).

The examples of the formation of the cross-links by the imine bonds are described for imparting heat resistance to the thermoplastic polyimide as the component (a), but the method of curing the thermoplastic polyimide as the component (a) is not limited thereto, and for example, an epoxy resin curing agent, or the like may be blended and cured.

The adhesive layer AD may further contain, as an optional component, an inorganic filler, an organic filler, a plasticizer, a hardening accelerator, a coupling agent, a pigment, a flame retardant, and the like as appropriate within a range that does not impair the effects of the present invention. Here, examples of the inorganic filler include: silicon dioxide, aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicon fluoride, phosphinate metal salts, and the like. These may be used singly or in combination of two or more.

In the adhesive layer AD, the content of the component (B) is preferably in the range of 10 parts by weight or more and 350 parts by weight or less, more preferably in the range of 50 parts by weight or more and 350 parts by weight or less, and most preferably in the range of 76 parts by weight or more and 250 parts by weight or less, relative to 100 parts by weight of the component (a). When the content of the component (B) is less than 10 parts by weight relative to 100 parts by weight of the component (a), the effect of lowering the dielectric loss tangent may not be sufficiently exhibited. On the other hand, if the weight ratio of the component (B) exceeds 350 parts by weight, the adhesion of the adhesion layer AD may be lowered.

In order to reduce the thickness ratio of the adhesive layer AD to the thickness of the resin laminate 101 to, for example, less than 0.5, it is important to reduce the dielectric loss tangent of the adhesive layer AD to a minimum in order to ensure connection reliability after circuit processing. From this viewpoint, the content of the component (B) is preferably in the range of 50 parts by weight or more and 350 parts by weight or less, more preferably in the range of 76 parts by weight or more and 350 parts by weight or less, and most preferably in the range of 76 parts by weight or more and 250 parts by weight or less, relative to 100 parts by weight of the component (a).

In order to achieve both the desired dielectric characteristics and adhesion, the total amount of the component (a) and the component (B) is preferably 50 wt% or more, more preferably 60 wt% to 95 wt%, and most preferably 70 wt% to 95 wt% with respect to the entire adhesive layer AD.

In the case of application to a circuit board, the dielectric loss tangent of the adhesive layer AD at 10GHz is preferably less than 0.0020, more preferably less than 0.0013, in order to suppress dielectric loss. This can reduce transmission loss when applied to a circuit board or the like for transmitting a high-frequency signal of 10GHz or more. When the dielectric loss tangent of the adhesive layer AD at 10GHz is 0.0020 or more, there is a problem that loss of an electric signal or the like is likely to occur in a transmission path of a high-frequency signal when applied to a circuit board. The lower limit of the dielectric loss tangent of the adhesive layer AD at 10GHz is not particularly limited.

In addition, for example, in the case of application to a circuit board, the relative dielectric constant of the subsequent layer AD at 10GHz is preferably 4.0 or less in order to secure impedance matching. If the relative dielectric constant of the adhesive layer AD at 10GHz exceeds 4.0, the dielectric loss of the adhesive layer AD increases when applied to a circuit board, and there is a problem that loss of an electrical signal or the like is likely to occur on a transmission path of a high-frequency signal.

The average thermal expansion coefficient of the adhesive layer AD in the in-plane direction orthogonal to the thickness direction from 250 ℃ to 100 ℃ may exceed 30ppm/K. Since the adhesive layer AD has low elasticity, even if the average thermal expansion coefficient in the in-plane direction exceeds 30ppm/K, the internal stress generated at the time of lamination can be relaxed.

The adhesive layer AD described above has excellent flexibility and dielectric characteristics (low dielectric constant and low dielectric loss tangent).

< resin laminate >)

In the metal-clad laminate 100, in order to suppress occurrence of cracks in plated parts of through holes or through holes after circuit processing, the average coefficient of thermal expansion in the thickness direction (lamination direction) of the resin laminate 101 including the first insulating resin layer 40A, the adhesive layer AD, and the second insulating resin layer 40B from the reference temperature of 25 ℃ to 125 ℃ is preferably less than 400ppm/K. When the average thermal expansion coefficient in the thickness direction of the resin laminate 101 is 400ppm/K or more, stress due to thermal expansion and contraction after circuit processing is concentrated on the plated portions of the through holes or the through holes, and cracking tends to be strong. The smaller the average thermal expansion coefficient in the thickness direction of the resin laminate 101 is, the better from the viewpoint of preventing cracking in the plated portion of the through hole or the through hole, but in order to reduce the transmission loss at the time of high frequency signal transmission, the more preferably the average thermal expansion coefficient in the thickness direction is in the range of 100ppm/K to 350ppm/K, and most preferably in the range of 200ppm/K to 300ppm/K, in view of low dielectric loss tangent of the entire resin laminate 101.

The average thermal expansion coefficient in the thickness direction can be controlled to be within the above range by the storage elastic coefficient of each layer, the thickness ratio, and the like of the first insulating resin layer 40A, the adhesive layer AD, and the second insulating resin layer 40B constituting the resin laminate 101.

In the metal-clad laminate 100, in order to ensure dimensional stability after circuit processing, the average thermal expansion coefficient in the in-plane direction perpendicular to the thickness direction (lamination direction) of the resin laminate 101 may be, for example, 10ppm/K or more, preferably 10ppm/K or more and 30ppm/K or less, and more preferably 15ppm/K or more and 25ppm/K or less. If the average thermal expansion coefficient in the in-plane direction is less than 10ppm/K or exceeds 30ppm/K, warpage occurs or dimensional stability is lowered.

The average thermal expansion coefficient in the thickness direction and the average thermal expansion coefficient in the in-plane direction of the present invention can be measured by the method described in examples described below.

For example, in the case of application to a circuit board, the dielectric loss tangent of the resin laminate 101 at 10GHz is preferably 0.0030 or less, more preferably 0.0028 or less, and still more preferably 0.0025 or less, in order to suppress dielectric loss. If the dielectric loss tangent of the resin laminate 101 at 10GHz exceeds 0.0030, the dielectric loss of an electric signal or the like tends to occur in the transmission path of a high-frequency signal when applied to a circuit board.

In addition, in the case of application as an insulating layer of a circuit board, the resin laminate 101 preferably has a relative dielectric constant of 4.0 or less at 10GHz in order to secure impedance matching. If the relative dielectric constant of the resin laminate 101 at 10GHz exceeds 4.0, dielectric loss increases when applied to a circuit board, and defects such as loss of an electrical signal tend to occur in a transmission path of a high-frequency signal.

< layer thickness >)

In the metal-clad laminate 100, the thickness of the metal layers 110A and 110B is not particularly limited, and for example, in the case of using a metal foil such as a copper foil, it is preferable that the thickness is 35 μm or less, and more preferably in the range of 5 μm to 25 μm. The lower limit of the thickness of the metal foil is preferably set to 5 μm from the viewpoint of production stability and operability.

In the metal-clad laminate 100, when the thickness of the resin laminate 101 (i.e., the total thickness of the first insulating resin layer 40A, the adhesive layer AD, and the second insulating resin layer 40B) is T1, the thickness T1 is preferably in the range of 70 μm to 500 μm, and more preferably in the range of 100 μm to 300 μm. When the thickness T1 is less than 70 μm, the effect of reducing the transmission loss at the time of producing the circuit board becomes insufficient, and when it exceeds 500 μm, productivity may be lowered.

The thickness T2 of the adhesive layer AD is preferably in the range of 1 μm to 450 μm, more preferably in the range of 10 μm to 250 μm, for example. If the thickness T2 of the adhesion layer AD is less than the lower limit value, the following problem may occur: the low dielectric loss tangent becomes insufficient, and thus, sufficient dielectric characteristics cannot be obtained, and it is difficult to obtain sufficient adhesion to an insulating resin layer. On the other hand, if the thickness of the adhesive layer AD exceeds the upper limit value, there may be a problem such as a decrease in dimensional stability.

The ratio (T2/T1) of the thickness T2 of the adhesive layer AD to the thickness T1 is preferably in the range of 0.1 to 0.96, more preferably in the range of 0.1 to 0.75. If the ratio (T2/T1) is less than 0.1, the low dielectric loss tangent may be insufficient, and if it exceeds 0.96, the dielectric characteristics may not be sufficiently obtained, and if it exceeds the dielectric characteristics, the dimensional stability may be lowered. Here, in order to make connection reliability after circuit processing reliable, it is preferable to set the ratio (T2/T1) to be small in order to easily control the average thermal expansion coefficient in the thickness direction of the resin laminate 101. When the average thermal expansion coefficient in the thickness direction of the resin laminate 101 is less than 400ppm/K, the occurrence of cracks in plated portions of the through holes or through holes after circuit processing can be suppressed, and connection reliability can be ensured. In the present invention, the thermoplastic polyimide as the component (a) and the polystyrene elastomer as the component (B) are blended as the material of the adhesive layer AD, whereby the resin laminate 101 can be sufficiently reduced in dielectric loss tangent even if the ratio (T2/T1) is reduced. In this case, the ratio (T2/T1) is, for example, preferably in the range of 0.1 to less than 0.5, more preferably in the range of 0.1 to 0.45, and particularly preferably in the range of 0.3 to 0.4 in order to achieve both low dielectric loss tangent of the entire resin laminate 101 and connection reliability after circuit processing.

The thickness T3 of each of the first insulating resin layer 40A and the second insulating resin layer 40B is preferably in the range of, for example, 8 μm to 50 μm, more preferably 12 μm to 50 μm, still more preferably 20 μm to 50 μm, and most preferably 38 μm to 45 μm. If the thickness T3 of the first insulating resin layer 40A and the second insulating resin layer 40B is less than the lower limit, warpage of the metal-clad laminate 100 may occur. If the thickness T3 of the first insulating resin layer 40A and the second insulating resin layer 40B exceeds the upper limit value, there occurs a problem such as a decrease in the transmission characteristics when the circuit board is manufactured. Further, the first insulating resin layer 40A and the second insulating resin layer 40B may not necessarily have the same thickness.

The thickness of the non-thermoplastic polyimide layer 20A and the non-thermoplastic polyimide layer 20B is preferably in the range of 6 μm to 45 μm, more preferably in the range of 9 μm to 30 μm, respectively, from the viewpoint of securing the function as a base layer and the conveyance property at the time of manufacturing and at the time of thermoplastic polyimide coating. When the thickness of the non-thermoplastic polyimide layer 20A or 20B is less than the lower limit, electrical insulation or workability becomes insufficient, and when the upper limit is exceeded, productivity is lowered.

From the viewpoint of securing the adhesion function, the thicknesses of the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B are each preferably in the range of 1 μm to 10 μm, more preferably in the range of 1 μm to 5 μm. When the thicknesses of the thermoplastic polyimide layer 10A, the thermoplastic polyimide layer 10B, the thermoplastic polyimide layer 30A, and the thermoplastic polyimide layer 30B are less than the lower limit, the adhesion becomes insufficient, and when the upper limit is exceeded, the dimensional stability tends to be deteriorated.

[ production of Metal-clad laminate ]

Although not shown, the metal-clad laminate 100 can be manufactured according to, for example, method 1 or method 2 described below. In this case, the component (a) and the component (B) constituting the adhesive layer AD are preferably used as a resin composition. The thermoplastic polyimide as the component (a) used in the adhesive layer AD may be crosslinked as described above.

The resin composition can be prepared, for example, by blending and mixing a polystyrene elastomer as the component (B) in a resin solution of a thermoplastic polyimide as the component (a) prepared using an arbitrary solvent. In this case, in order to uniformly mix the thermoplastic polyimide and the polystyrene elastomer, the thermoplastic polyimide and the polystyrene elastomer may be mixed in a state in which the polystyrene elastomer is dissolved in a solvent, or a solvent exhibiting high solubility with respect to the polystyrene elastomer may be added. In addition, the resin composition may contain an amino compound or an optional component for crosslinking the thermoplastic polyimide as the component (a).

The content of the component (B) in the resin composition is in the range of 10 parts by weight or more and 350 parts by weight or less, preferably in the range of 50 parts by weight or more and 350 parts by weight or less, more preferably in the range of 76 parts by weight or more and 250 parts by weight or less, relative to 100 parts by weight of the component (a). When the content of the component (B) is less than 10 parts by weight relative to 100 parts by weight of the component (a), the effect of lowering the dielectric loss tangent may not be sufficiently exhibited. On the other hand, if the weight ratio of the component (B) exceeds 350 parts by weight, the adhesion at the time of forming a resin film may be lowered, and the solid content concentration in the resin composition is too high, the viscosity may be raised, and the handleability may be lowered.

In order to achieve both the desired dielectric characteristics and adhesion, the total amount of the component (a) and the component (B) is preferably 50% by weight or more, more preferably 60% by weight to 95% by weight, and most preferably 70% by weight to 95% by weight, based on the total solid content in the resin composition. The solid content in the resin composition means the total of the components after the solvent is removed.

The resin composition may contain a solvent such as an organic solvent. The thermoplastic polyimide as the component (a) is soluble in a solvent, and the polystyrene elastomer as the component (B) is excellent in solubility in an aromatic hydrocarbon solvent such as xylene or toluene, for example, so that the resin composition can be prepared as a polyimide solution (varnish) containing a solvent. As the organic solvent, for example, a mixed solvent obtained by mixing one or more selected from N, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, cresol, and the like, with the aromatic hydrocarbon solvent in an arbitrary ratio is preferably used. The content of the solvent is not particularly limited, and is preferably adjusted to a total content of the component (a) and the component (B) of about 5 to 30% by weight based on the total composition. The viscosity of the resin composition is preferably in the range of 3000mpa·s to 100000mpa·s, more preferably in the range of 5000mpa·s to 50000mpa·s, for example, in order to improve the handleability when the resin composition is applied and to facilitate formation of a coating film having a uniform thickness. When the viscosity is outside the above-mentioned range, defects such as uneven thickness and streaks are likely to occur in the film when the coating operation is performed by a coater or the like.

Method 1 >

The method 1 comprises the following steps: the resin composition serving as the adhesive layer AD is formed into a sheet shape to form an adhesive sheet, and the adhesive sheet is arranged between the first insulating resin layer 40A of the first single-sided metal-clad laminate (C1) and the second insulating resin layer 40B of the second single-sided metal-clad laminate (C2) and bonded thereto, and then the adhesive layer AD is formed by thermocompression bonding to form the metal-clad laminate 100.

Method 2 >

The method 2 comprises the following steps: the metal clad laminate 100 is produced by applying a resin composition to be the adhesive layer AD to either or both of the first insulating resin layer 40A of the first single-sided metal clad laminate (C1) and the second insulating resin layer 40B of the second single-sided metal clad laminate (C2) at a predetermined thickness, drying the layers, and then bonding the first single-sided metal clad laminate (C1) to the resin layer (or the coating film) side of the second single-sided metal clad laminate (C2) and thermocompression bonding the layers.

The first single-sided metal-clad laminate (C1) and the second single-sided metal-clad laminate (C2) used in the method 1 and the method 2 can be produced, for example, by: the application of the polyamic acid solution to the metal foil and the drying are repeated a predetermined number of times, and then imidization is performed.

The adhesive sheet used in the method 1 can be manufactured by, for example, the following method: the resin composition is applied to an arbitrary support substrate, dried, and then peeled off from the support substrate to prepare an adhesive sheet.

In the above description, the method of applying the resin composition or the polyamic acid solution to the metal foil, the support substrate, the first insulating resin layer 40A, and the second insulating resin layer 40B is not particularly limited, and may be applied by, for example, an applicator such as an angle wheel, a die, a knife, or a die lip.

The metal-clad laminate 100 of the present embodiment thus obtained can be used to manufacture a circuit board such as a single-sided FPC or a double-sided FPC by performing wiring circuit processing by etching or the like on the metal layer 110A and/or the metal layer 110B.

[ Circuit Board ]

When described with reference to fig. 1, a circuit board as an embodiment of the present invention can be manufactured as follows: one or both of the two metal layers 110A, 110B of the metal-clad laminate 100 are patterned to form a wiring layer according to a conventional method. The circuit board of the present embodiment includes: the first wiring layer formed by circuit processing the metal layer 110A, the first insulating resin layer 40A laminated on at least one side surface of the first wiring layer, the second wiring layer formed by circuit processing the metal layer 110B, the second insulating resin layer 40B laminated on at least one side surface of the second wiring layer, and the adhesive layer AD laminated between these layers so as to be in contact with the first insulating resin layer 40A and the second insulating resin layer 40B. In the circuit board of the present embodiment, the total thickness T1 of the resin laminate 101 including the first insulating resin layer 40A, the adhesive layer AD, and the second insulating resin layer 40B is in the range of 70 μm to 500 μm, and the ratio (T2/T1) of the thickness T2 of the adhesive layer AD to the total thickness T1 is in the range of 0.10 to 0.96, and the adhesive layer AD contains the following components (a) and (B);

(A) Thermoplastic polyimide,

And

In the circuit board of the present embodiment, after forming a through hole or a through hole according to a conventional method, plating may be performed on the inner wall of the hole. In this case, in the circuit board according to the present embodiment, the dielectric loss tangent of the entire resin laminate 101 can be sufficiently reduced without increasing the thickness ratio of the adhesive layer AD, and therefore excellent dielectric characteristics and connection reliability can be achieved. That is, the circuit board of the present invention can ensure conduction in the through hole or the through hole, has excellent reliability, and can cope with high-frequency signal transmission. In particular, in the circuit board of the present embodiment, when the average thermal expansion coefficient in the thickness direction of the resin laminate 101 from the reference temperature of 25 ℃ to 125 ℃ is less than 400ppm/K, the occurrence of cracks in the plated portion of the through hole or the through hole can be suppressed, sufficient conduction can be ensured, and excellent reliability is achieved. The circuit board of the present embodiment can be preferably used as, for example, an FPC, a rigid-flexible circuit board, or the like.

[ electronic device, electronic apparatus ]

The electronic device and the electronic apparatus according to the present embodiment include the circuit board. Examples of the electronic device according to the present embodiment include: a liquid crystal display, an organic Electroluminescence (EL) display, a display device such as electronic paper, organic EL lighting, a solar cell, a touch panel, a camera module, an inverter, a converter, and structural members thereof, and the like. Examples of the electronic device include HDD, DVD, mobile phone, smart phone, tablet terminal, electronic control unit (electronic control unit, ECU) of automobile, power control unit (power control unit, PCU), and the like. The circuit board is preferably used as a component such as a wiring of a movable portion, a cable, or a connector in these electronic devices or electronic apparatuses.

Examples (example)

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, various measurements and evaluations were as follows.

[ measurement of viscosity ]

The viscosity at 25℃was measured using an E-type viscometer (trade name: DV-II+Pro, manufactured by Brookfield Co.). The rotational speed was set so that the torque became 10% to 90%, and after 2 minutes passed from the start of measurement, the value at which the viscosity was stable was read.

[ measurement of weight average molecular weight (Mw) of polyimide ]

The weight average molecular weight was measured by a gel permeation chromatograph (Gel Permeation Chromatograph) (manufactured by Tosoh Co., ltd., trade name: HLC-8220 GPC). Polystyrene was used as a standard substance, and Tetrahydrofuran (THF) was used as a developing solvent.

[ measurement of relative permittivity (Dk) and dielectric loss tangent (Df) ]

The relative dielectric constant and dielectric loss tangent of the resin sheet at 10GHz were measured using a vector network analyzer (Vector Network Analyzer) (manufactured by Agilent, trade name E8363C) and an SPDR resonator. In addition, the materials used in the assay are at temperature: the material is placed for 24 hours under the conditions of 24-26 ℃ and humidity of 45-55%RH.

[ measurement of average coefficient of thermal expansion in-plane direction (XY-CTE) ]

For a polyimide film having a size of 3mm×20mm, a thermal mechanical analyzer (trade name: 4000SA, manufactured by Bruker) was used, and the polyimide film was heated from 30 ℃ to 265 ℃ at a constant temperature-increasing rate while applying a load of 5.0g, and was further cooled at a rate of 5 ℃/min after being held at the temperature for 10 minutes, and an average thermal expansion coefficient (thermal expansion coefficient) from 250 ℃ to 100 ℃ was obtained.

[ measurement of average coefficient of thermal expansion in thickness direction (Z-CTE) ]

A polyimide film having a size of 7mm X7 mm was subjected to pretreatment using a laser thermal dilatometer (trade name: LIX-1 type manufactured by Alvac) in a helium atmosphere, and then heated to 200℃at a heating rate of 3℃per minute while applying a load of 17.0g, and then cooled to 25℃at a cooling rate of 3℃per minute. Then, the temperature was lowered from 25℃to-65℃at a temperature lowering rate of 3℃per minute, and the temperature was raised from-65℃to 200℃at a temperature raising rate of 3℃per minute, and the average thermal expansion coefficients (length change rates) in the thickness direction were determined at the time of the temperature raising from-65℃to 25℃and from 25℃to 125 ℃.

[ measurement of storage modulus of elasticity and glass transition temperature (Tg) ]

For the storage modulus of elasticity, a polyimide film or a cured resin sheet was cut into 5 mm. Times.20 mm pieces, and the pieces were subjected to stepwise heating at a temperature rising rate of 4℃per minute from 30℃to 400℃using a dynamic viscoelasticity apparatus (DMA: manufactured by TA Instruments, trade name: RSA-G2) at a frequency of 11 Hz. The maximum temperature at which the value of Tan δ in the measurement becomes maximum is defined as Tg. In addition, the storage modulus of elasticity at 30℃was 1.0X10⁸A storage modulus of elasticity at 300 ℃ of less than 3.0X10 at Pa or above⁷The polyimide of Pa was judged to be "thermoplastic", and the storage modulus of elasticity at 30℃was 1.0X10⁹A storage elastic modulus at 300 ℃ of 3.0X10 at Pa or above⁸Polyimide of Pa or more was judged as "non-thermoplastic".

[ connection reliability test ]

The following test samples were prepared: a copper-clad laminate sheet comprising a copper foil of 12 μm thickness was drilled with a 150 μm diameter drill using an NC drill (trade name: A-120D type manufactured by the same Co., ltd.) and after the photoresist removal treatment, a copper-clad layer of about 10 μm to 15 μm thickness was formed. A gas phase cold and hot impact device (trade name: TSA-71H-W, manufactured by Espec Co.) was used, and a treatment was carried out in 1,000 cycles using a procedure of treating at-65℃for 30 minutes and then at 125℃for 30 minutes as one cycle. The cross section of the interlayer connection processed portion of the sample after the test was observed by an electron microscope, and the copper plating layer was judged to be satisfactory if no crack was generated, and the copper plating layer was judged to be unacceptable if a crack was generated.

Abbreviations used in this example refer to the following compounds.

BPDA:3,3', 4' -biphenyltetracarboxylic dianhydride

PMDA: pyromellitic dianhydride

m-TB:2,2 '-dimethyl-4, 4' -diaminobiphenyl

BAPP:2, 2-bis [4- (4-aminophenoxy) phenyl ] propane

TPE-R:1, 3-bis (4-aminophenoxy) benzene

BTDA:3,3', 4' -benzophenone tetracarboxylic dianhydride

DDA: an aliphatic diamine having 36 carbon atoms (manufactured by Croda Japan, trade name: pr Li Amin (PRIAMINE) 1074, having an amine value of 210mgKOH/g, a mixture of dimer diamines having a cyclic structure and a chain structure, component (a) of 97.9%, component (b) of 0.3%, component (c) of 1.8%)

The "%" of the components (a), (b) and (c) refer to the area percentage of the chromatogram in the GPC measurement. The molecular weight of DDA is calculated by the following formula.

Molecular weight=56.1×2×1000/amine number

Elastomer resin 1: manufactured by KRATON (KRATON), trade name: MD1653MO (hydrogenated polystyrene elastomer, styrene unit content: 30% by weight, mw:80,499, acid value-free)

Elastomer resin 2: manufactured by KRATON (KRATON), trade name: a1535HU (hydrogenated polystyrene elastomer resin, styrene unit content: 58% by weight, mw:230,305, acid value-free)

NMP: n-methyl-2-pyrrolidone

DMAc: n, N-dimethylacetamide

N-12: dodecanedioic acid dihydrazide

OP935: aluminum organic phosphinate (trade name: ai Kesuo Lite (Exolit) OP935 manufactured by Clariant Japan Co., ltd.)

SR-3000: phosphate (trade name: SR-3000, non-halogen aromatic condensed phosphate, phosphorus content: 7.0%) manufactured by Daba chemical industry Co., ltd.)

Synthesis example 1

Preparation of resin solution for adhesive layer

A500 ml separable flask was charged with 21.34g of BTDA (0.06622 mol), 12.99g of BPDA (0.04414 mol), 46.7042g of DDA (0.08741 mol), 8.97104g of BAPP (0.02185 mol), 126g of NMP and 84g of xylene, and the mixture was thoroughly mixed at 40℃for 1 hour to prepare a polyamic acid solution. The polyamic acid solution was heated to 190℃and stirred for 5 hours, and xylene was added in an amount such that the solid content concentration after polymerization was 31%, to prepare a polyimide solution 1 (solid content: 31% by weight, weight average molecular weight: 35,886, viscosity: 2.580 mPa.s, thermoplastic polyimide) having been imidized.

Synthesis example 2

Preparation of resin solution for adhesive layer

A1000 ml separable flask was charged with 34.04g of BTDA (0.1057 mol), 55.89g of DDA (0.1046 mol), 126g of NMP and 84g of xylene under a nitrogen stream, and the mixture was thoroughly mixed at 40℃for 1 hour to prepare a polyamic acid solution. The polyamic acid solution was heated to 190℃and stirred for 5 hours, and xylene was added in an amount such that the solid content concentration after polymerization was 31%, to prepare an imidized polyimide solution 2 (solid content: 31% by weight, weight average molecular weight: 52,800, viscosity: 4.750 mPas, thermoplastic polyimide).

Synthesis example 3

Preparation of polyamic acid solution for insulating resin layer

Under a nitrogen stream, 31.88g of m-TB (0.1502 mol) and 3.24g of BAPP (0.0079 mol) were charged into the reaction vessel, and DMAc was dissolved in the reaction vessel under stirring at room temperature in an amount such that the concentration of the solid matter after polymerization was 15% by weight. Then, 16.98g of PMDA (0.0778 mol) and 22.90g of BPDA (0.0778 mol) were added, followed by continuing stirring at room temperature for 3 hours to carry out polymerization, thereby producing a polyamic acid solution 1 (viscosity: 26,500 mPa. Multidot.s). The storage modulus of elasticity of a polyimide film obtained by applying the polyamic acid solution 1 to a substrate, drying it and imidizing it was measured and found to be "non-thermoplastic".

Synthesis example 4

Preparation of polyamic acid solution for insulating resin layer

Polyamide acid solution 2 (viscosity: 2,650 mPas) was prepared in the same manner as in Synthesis example 3 except that 3.48g of m-TB (0.0164 mol), 27.14g of TPE-R (0.0928 mol) and DMAc in an amount of 12% by weight in terms of solid content concentration after polymerization were charged, and 9.72g of PMDA (0.0446 mol) and 19.6731g of BPDA (0.0668 mol) were used as raw materials. The storage modulus of elasticity of a polyimide film obtained by applying the polyamic acid solution 2 to a substrate, drying it and imidizing it was measured and the result was "thermoplastic".

Production example 1

Preparation of resin sheet 1 for adhesive layer

To 100g of polyimide solution 1 (31 g as a solid content), 1.1g of N-12 (0.004 mol), 26.4g of elastomer resin 1, 2.2g of OP935 and 2.2g of SR-3000 were blended, and xylene was added so as to make the solid content 26.5 wt% and diluted, followed by stirring, to thereby prepare adhesive composition 1.

The adhesive composition 1 was applied to the silicone-treated surface of a release substrate (vertical×horizontal×thickness=320 mm×240mm×25 μm) so that the thickness after drying became 60 μm, and then heated and dried at 120 ℃ for 30 minutes, and peeled off from the release substrate, thereby producing a resin sheet 1. The relative dielectric constants (Dk) and dielectric loss tangents (Df) of the cured resin sheet 1 obtained by heat-treating the resin sheet 1 at 180℃for 2 hours were 2.46 and 0.0011, respectively.

Production example 2

Preparation of resin sheet 2 for adhesive layer

Resin sheets 2 were obtained in the same manner as in production example 1, except that the adhesive composition 1 was applied so that the thickness after drying was 50 μm each.

Production example 3

Preparation of resin sheet 3 for adhesive layer

To 100g of polyimide solution 1 (31 g as a solid content), 1.1g of N-12 (0.004 mol) and 55.8g of elastomer resin 1 were prepared, and xylene was added so as to make the solid content 29.0 wt% and diluted, followed by stirring, to prepare adhesive composition 3.

The adhesive composition 3 was applied to the silicone-treated surface of a release substrate (vertical×horizontal×thickness=320 mm×240mm×25 μm) so that the thickness thereof after drying became 60 μm, and then heated and dried at 120 ℃ for 30 minutes, and peeled off from the release substrate, thereby producing a resin sheet 3. The relative dielectric constant (Dk) and the dielectric loss tangent (Df) of the cured resin sheet 3 obtained by heat-treating the resin sheet 3 at 180℃for 2 hours were 2.45 and 0.0009, respectively.

Reference example 1

To 100g of polyimide solution 1 (31 g as a solid content), 1.1g of N-12 (0.004 mol), 26.4g of elastomer resin 2, 2.2g of OP935 and 2.2g of SR-3000 were blended, and xylene was added so as to make the solid content 26.5 wt% and diluted, followed by stirring, whereby the resulting adhesive composition had low fluidity and was in the form of a gel, and thus, it was impossible to make the adhesive composition into sheets.

Production example 4

Preparation of resin sheet 4 for adhesive layer

To 100g of polyimide solution 2, 1.1g of N-12 (0.004 mol) was prepared, and 7.8g of OP935 and 14.0g of xylene were added and diluted, followed by stirring for 1 hour, to thereby prepare adhesive composition 4.

The adhesive composition 4 was applied to the silicone-treated surface of a release substrate (vertical×horizontal×thickness=320 mm×240mm×25 μm) so that the thickness after drying became 50 μm, and then heated and dried at 120 ℃ for 30 minutes, and peeled off from the release substrate, thereby producing a resin sheet 4. The relative dielectric constants (Dk) and dielectric loss tangents (Df) of the cured resin sheets 4 obtained by heat-treating the resin sheets 4 at 180 ℃ for 2 hours were 2.68 and 0.0024, respectively.

Production example 5

Preparation of resin sheet 5 for adhesive layer

A resin sheet 5 was obtained in the same manner as in production example 4, except that the adhesive composition 4 was applied so that the thickness after drying became 30 μm.

Production example 6

< preparation of Single-sided Metal-clad laminate 1 >

The polyamic acid solution 2 was uniformly applied to the copper foil 1 (electrolytic copper foil, thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) so that the thickness after curing was about 3 μm to 5 μm, and then dried by heating at 120℃to remove the solvent. Next, the polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing was about 40 μm to 44 μm, and the solvent was removed by heat drying at 120 ℃. Further, the polyamic acid solution 2 was uniformly applied so that the thickness after curing was about 3 to 5. Mu.m, and then dried by heating at 120℃to remove the solvent. Further, a single-sided metal clad laminate 1 having a polyimide layer thickness of 50 μm was produced by performing stepwise heat treatment from 120℃to 360℃to complete imidization.

Preparation of polyimide film 1

The copper foil layer of the single-sided metal clad laminate 1 was removed by etching using an aqueous solution of ferric chloride to prepare a polyimide film 1 having a thickness of 50 μm. XY-CTE was 20ppm/K, and relative dielectric constant (Dk) and dielectric loss tangent (Df) were 3.40 and 0.0034, respectively. In addition, the polyimide film 1 had a storage modulus of elasticity of 5.9X10 at 125 ℃ ⁹Pa。

Production example 7

< preparation of Single-sided Metal-clad laminate 2 >

The polyamic acid solution 2 was uniformly applied to the copper foil 1 so that the thickness thereof after curing was about 3 μm to 5 μm, and then dried by heating at 120℃to remove the solvent. Next, the polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing was about 35 μm to 39 μm, and the solvent was removed by heat drying at 120 ℃. Further, the polyamic acid solution 2 was uniformly applied so that the thickness after curing was about 3 to 5. Mu.m, and then dried by heating at 120℃to remove the solvent. Further, a single-sided metal clad laminate 2 having a polyimide layer thickness of 45 μm was produced by performing stepwise heat treatment from 120℃to 360℃to complete imidization.

Production example 8

< preparation of Single-sided Metal-clad laminate 3 >

The polyamic acid solution 2 was uniformly applied to the copper foil 1 so that the thickness thereof after curing was about 2 μm to 3 μm, and then dried by heating at 120℃to remove the solvent. Next, the polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing was about 21 μm, and dried by heating at 120 ℃ to remove the solvent. Further, the polyamic acid solution 2 was uniformly applied so that the thickness after curing was about 2 μm to 3 μm, and then dried by heating at 120℃to remove the solvent. Further, a single-sided metal clad laminate 3 having a polyimide layer thickness of 25 μm was produced by performing stepwise heat treatment from 120℃to 360℃to complete imidization.

Production example 9

< preparation of Single-sided Metal-clad laminate 4 >

The polyamic acid solution 2 was uniformly applied to the copper foil 1 so that the thickness thereof after curing was about 2 μm to 3 μm, and then dried by heating at 120℃to remove the solvent. Next, the polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing was about 14 μm to 16 μm, and the solvent was removed by heat drying at 120 ℃. Further, the polyamic acid solution 2 was uniformly applied so that the thickness after curing was about 2 μm to 3 μm, and then dried by heating at 120℃to remove the solvent. Further, a single-sided metal clad laminate 4 having a polyimide layer thickness of 20 μm was produced by performing stepwise heat treatment from 120℃to 360℃to complete imidization.

Production example 10

< preparation of Single-sided Metal-clad laminate 5 >

The polyamic acid solution 2 was uniformly applied to the copper foil 1 so that the thickness thereof after curing was about 1 μm to 2 μm, and then dried by heating at 120℃to remove the solvent. Next, the polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing was about 6 μm to 8 μm, and the solvent was removed by heat drying at 120 ℃. Further, the polyamic acid solution 2 was uniformly applied so that the thickness after curing was about 1 μm to 2. Mu.m, and then dried by heating at 120℃to remove the solvent. Further, a single-sided metal clad laminate 5 having a polyimide layer thickness of 10 μm was produced by performing stepwise heat treatment from 120℃to 360℃to complete imidization.

Preparation of polyimide film 2 to polyimide film 5

The copper foil layers of the single-sided metal clad laminate 2 to the single-sided metal clad laminate 5 were removed by etching with an aqueous solution of ferric chloride to prepare polyimide films 2 to 5. The relative dielectric constants (Dk) and dielectric loss tangents (Df) of the polyimide films 2 to 5 and the storage elastic coefficients at 125 ℃ are equal to those of the polyimide film 1.

Example 1

Two single-sided metal clad laminate plates 2 were prepared, and the respective insulating resin layer side surfaces were overlapped with both surfaces of the resin sheet 1, and pressure of 3.5MPa was applied at 180 ℃ for 2 hours and pressure-bonded, to prepare a double-sided metal clad laminate plate 1. The metal clad laminate 1 did not generate cracks in the copper clad after the connection reliability test. The resin laminate 1 (thickness: 150 μm) prepared by etching the copper foil layer in the metal clad laminate 1 had Z-CTE of 154ppm/K, 310ppm/K, XY-CTE of 24ppm/K, relative dielectric constant (Dk) and dielectric loss tangent (Df) of 3.03 and 0.0027, respectively, from a reference temperature of 25℃to-65℃and 125 ℃. The evaluation results are shown in table 1.

Example 2

A double-sided metal-clad laminate 2 and a resin laminate 2 (thickness: 150 μm) were obtained in the same manner as in example 1, except that the single-sided metal-clad laminate 1 and the resin sheet 2 were used. The evaluation results are shown in table 1.

Example 3

The adhesive composition 1 was applied to the insulating resin layer of the single-sided metal-clad laminate 3 so that the thickness after drying was 50 μm, and then, was dried by heating at 120℃for 10 minutes, thereby obtaining a single-sided metal-clad laminate 1 with an adhesive layer. The insulating resin layer of the single-sided metal-clad laminate 3 was overlapped with the adhesive layer side of the single-sided metal-clad laminate 1 with the adhesive layer, and the double-sided metal-clad laminate 3 was prepared by applying a pressure of 3.5MPa at 180 ℃ for 2 hours and performing pressure bonding. Further, the copper foil layer in the metal clad laminate 3 was etched away to obtain a resin laminate 3 (thickness: 100 μm). The evaluation results are shown in table 1.

Example 4

A double-sided metal-clad laminate 4 and a resin laminate 4 (thickness: 100 μm) were obtained in the same manner as in example 3, except that the adhesive composition 1 was applied to the insulating resin layer of the single-sided metal-clad laminate 4 so that the thickness after drying was 60 μm. The evaluation results are shown in table 1.

Example 5

A double-sided metal-clad laminate 5 and a resin laminate 5 (thickness: 150 μm) were obtained in the same manner as in example 1 except that the single-sided metal-clad laminate 2 and the resin sheet 3 were used. The evaluation results are shown in table 1.

Comparative example 1

Two single-sided metal clad laminate plates 5 were prepared, and after two resin sheets 4 and one resin sheet 5 were stacked on the surface of the insulating resin layer side of the first single-sided metal clad laminate plate 5, the insulating resin layer side of the second single-sided metal clad laminate plate 5 was further stacked so as to be in contact with the resin sheet 5, and pressure was applied at 180 ℃ for 2 hours under a pressure of 3.5MPa, whereby a double-sided metal clad laminate plate 6 and a resin laminate 6 (thickness: 150 μm) were obtained. The evaluation results are shown in table 1.

The results are summarized in Table 1.

TABLE 1

Reference example 2

A double-sided metal-clad laminate 7 and a resin laminate 7 (thickness: 150 μm) were obtained in the same manner as in example 1, except that the single-sided metal-clad laminate 1 and the resin sheet 4 were used. The metal clad laminate 7 did not generate cracks in the copper clad layer after the connection reliability test. The Z-CTE of the resin laminate 7 (thickness: 150 μm) was 60ppm/K, 272ppm/K, 24ppm/K, and 3.13 and 0.0031 respectively from the reference temperature of 25℃to-65℃and 125℃respectively.

In production examples 1 to 3, a low molecular weight styrene elastomer excellent in solubility was used, and thus the blending ratio was increased, and resin sheets having a dielectric loss tangent (Df) of 0.0012 or less were obtained.

In addition, the following was verified: examples 1 to 5 can provide a metal-clad laminate having both good connection reliability due to suppression of Z-CTE and low dielectric loss tangent (Df) of 0.003 or less, compared with comparative example 1.

Although the embodiments of the present invention have been described in detail for the purpose of illustration, the present invention is not limited to the embodiments, and various modifications are possible.

Claims

1. A metal clad laminate comprising:

a first metal layer;

a second metal layer;

an adhesive layer laminated between the first insulating resin layer and the second insulating resin layer so as to be in contact with each other, wherein the metal-clad laminate is characterized in that,

the total thickness T1 of the resin laminate including the first insulating resin layer, the adhesive layer and the second insulating resin layer is in the range of 70 [ mu ] m to 500 [ mu ] m, and the ratio of the thickness T2 of the adhesive layer to the total thickness T1, namely T2/T1, is in the range of 0.10 to 0.96,

The adhesive layer contains the following component (A) and component (B);

(A) Thermoplastic polyimide,

And

2. The metal-clad laminate according to claim 1, wherein the content of the component (B) is in the range of 10 parts by weight or more and 350 parts by weight or less relative to 100 parts by weight of the component (a).

3. The metal-clad laminate according to claim 1, wherein the resin laminate has a dielectric loss tangent of 0.0030 or less at 10GHz and the adhesive layer has a dielectric loss tangent of less than 0.0013 at 10 GHz.

4. The metal-clad laminate according to claim 1, wherein the storage elastic modulus at 125 ℃ of the first insulating resin layer and the second insulating resin layer are each 1.0 x 10⁹Pa～8.0×10⁹Pa.

5. The metal-clad laminate according to claim 1, wherein the resin laminate has an average coefficient of thermal expansion of less than 400ppm/K in a thickness direction from a reference temperature of 25 ℃ to 125 ℃.

6. The metal-clad laminate according to claim 1, wherein an average thermal expansion coefficient of the resin laminate as a whole in an in-plane direction orthogonal to a thickness direction from 250 ℃ to 100 ℃ is in a range of 10ppm/K or more and 30ppm/K or less.

7. The metal-clad laminate of claim 1 wherein

The first insulating resin layer and the second insulating resin layer each have a multilayer structure in which a thermoplastic polyimide layer, a non-thermoplastic polyimide layer, and a thermoplastic polyimide layer are sequentially laminated,

the adhesive layer is connected with the two thermoplastic polyimide layers.

8. A circuit substrate, comprising:

a first wiring layer;

a second wiring layer;

an adhesive layer laminated between the first insulating resin layer and the second insulating resin layer so as to be in contact with each other, wherein the circuit board is characterized in that,

the adhesive layer contains the following component (A) and component (B);

(A) Thermoplastic polyimide,

And

9. An electronic device comprising the circuit substrate of claim 8.

10. An electronic device comprising the circuit substrate according to claim 8.