Bond ply, circuit boards and striplines using the same

Abstract

To provide a bond ply capable of combining low dielectric tangent and dimensional stability.SOLUTION: A bond ply comprises a first adhesive layer, a polyimide layer and a second adhesive layer, in which a) a thickness of an entire bond ply is in the range of 50 μm or more and 300 μm or less, and a ratio of the thickness of the polyimide layer to the thickness of the entire bond ply is 0.2 or more and 0.9 or less, b) after drying at 80°C for 1 hour, the moisture absorption measured after conditioning for 24 hours under constant temperature and humidity at 23°C and 50% RH is 0.4 wt.% or less, and c) the storage elastic moduli at 50°C of the first adhesive layer and the second adhesive layer are each independently 1800 MPa or lower, and the maximum value of the storage elastic moduli at 180 to 260°C are each independently 800 MPa or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to bond ply, which is useful as an electronic component material, and to circuit boards and striplines using the same. [Background technology]

[0002] In recent years, with the miniaturization, weight reduction, and space-saving of electronic devices, the demand for flexible printed circuit boards (FPCs) has been increasing. These FPCs are thin, lightweight, flexible, and possess excellent durability even after repeated bending. Because FPCs enable three-dimensional and high-density mounting even in limited spaces, their applications are expanding to include wiring in the moving parts of electronic devices such as HDDs, DVDs, and smartphones, as well as components such as cables and connectors.

[0003] In addition to increased density, the performance of equipment has also improved, necessitating the handling of higher frequency transmission signals. When transmitting high-frequency signals, large transmission losses in the transmission path can lead to problems such as electrical signal loss and longer signal delays. For this reason, it has been proposed to use polyimide with a low dielectric loss tangent as the material for the multiple resin layers used in FPCs (for example, Patent Documents 1 and 2).

[0004] To support 5G (fifth-generation mobile communication system), there is a strong need to suppress transmission loss in the GHz band for striplines, which are a form of FPC and are applied as transmission lines such as RF cables. To suppress transmission loss in striplines, i) reducing the dielectric loss tangent of the resin material and ii) increasing the overall thickness of the resin layer are effective. For ii), an effective approach is to increase the thickness of the layer made of bonding sheets (adhesive resin layer) embedded in the stripline. However, since bonding sheets use resin materials that are flexible, have a low glass transition temperature and a large coefficient of thermal expansion, there is a concern that dimensional stability will decrease if the thickness is increased. Furthermore, there are problems such as damage such as abrasion and gouging to the adhesive resin layer during processes such as forming via holes (through holes) by laser processing, and resin leakage due to heat during soldering processes. Therefore, there are limitations to the approach of increasing the thickness of the bonding sheet. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-170417 [Patent Document 2] Japanese Patent Publication No. 2020-55186 [Overview of the project] [Problems that the invention aims to solve]

[0006] To compensate for the aforementioned shortcomings of bonding sheets, bond plies are used, which sandwich a relatively heat-resistant resin layer between adhesive resin layers. However, little research has been done to date on how to achieve both low dielectric loss tangent and dimensional stability in the resin materials used for bond plies.

[0007] The first object of the present invention is to provide a bond ply that can achieve both low dielectric loss tangent and dimensional stability, and the second object is to provide a circuit board such as a stripline that has low high-frequency signal transmission loss, excellent dimensional stability, and high reliability by using this bond ply. [Means for solving the problem]

[0008] As a result of diligent research, the inventors have discovered that the above problems can be solved in a bond ply with a structure in which a polyimide layer is sandwiched between adhesive resin layers, by using a resin with a low storage modulus as the adhesive resin layer, and by considering the thickness ratio of each layer and the overall moisture absorption rate, and have completed the present invention. In other words, the bond ply of the present invention is Polyimide layer, A first adhesive layer laminated on one side of the polyimide layer, A second adhesive layer is laminated on the side of the polyimide layer opposite to the first adhesive layer, It is a bonded ply equipped with adhesive. Furthermore, the bond ply of the present invention meets the following conditions a to c; a) The total thickness of the bond ply is within the range of 50 μm to 300 μm, and the ratio of the thickness of the polyimide layer to the total thickness of the bond ply is within the range of 0.2 to 0.9; b) After drying at 80°C for 1 hour, the moisture absorption rate measured after 24 hours of conditioning at a constant temperature and humidity of 23°C and 50%RH must be 0.4% by weight or less; c) The storage modulus of the first adhesive layer and the second adhesive layer at 50°C is independently 1800 MPa or less, and the maximum value of the storage modulus at 180-260°C is independently 800 MPa or less; It is characterized by satisfying the following conditions.

[0009] The bond ply of the present invention further meets the following condition d; d) The dielectric tangent at 10 GHz measured by a split post dielectric resonator (SPDR) after humidity conditioning for 24 hours under constant temperature and humidity conditions (normal state) of 23°C and 50% RH is 0.004 or less: It may satisfy the above.

[0010] In the bond ply of the present invention, the first adhesive layer and the second adhesive layer may each have a glass transition temperature (Tg) of 180°C or less.

[0011] In the bond ply of the present invention, the first adhesive layer and the second adhesive layer contain polyimide as a resin component, The polyimide may contain an acid anhydride residue derived from a tetracarboxylic acid anhydride component and a diamine residue derived from a diamine component, and may contain 50 mol% or more of a diamine residue derived from a dimer diamine composition mainly composed of a dimer diamine in which two terminal carboxylic acid groups of dimer acid are substituted with a primary aminomethyl group or an amino group.

[0012] In the bond ply of the present invention, the thermal expansion coefficient of the polyimide layer may be in the range of 1 ppm / K or more and 30 ppm / K or less.

[0013] In the bond ply of the present invention, the dielectric tangent at 10 GHz measured by a split post dielectric resonator (SPDR) after humidity conditioning for 24 hours under constant temperature and humidity conditions (normal state) of 23°C and 50% RH of the polyimide layer may be 0.006 or less.

[0014] In the bond ply of the present invention, the polyimide constituting the polyimide layer may contain a tetracarboxylic acid residue and a diamine residue, and the content of the diamine residue derived from the diamine compound represented by the following general formula (A1) may be 50 mol% or more with respect to all the diamine residues.

[0015]

Chemical formula

[0016] [In formula (A1), linking group Z represents a single bond or -COO-, Y independently represents a monovalent hydrocarbon having 1 to 3 carbon atoms which may be substituted with a halogen atom or a phenyl group, or an alkoxy group having 1 to 3 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkenyl group, n represents an integer of 0 to 2, and p and q independently represent an integer of 0 to 4.]

[0017] The circuit board of the present invention includes any of the above bond plies.

[0018] The stripline of the present invention a first metal layer, a first insulating resin layer composed of a single layer or multiple layers laminated on one surface of the first metal layer, a wiring layer provided in contact with the first insulating resin layer, a second metal layer, a second insulating resin layer composed of a single layer or multiple layers laminated on one surface of the second metal layer, an intermediate resin layer laminated between the first insulating resin layer and the second insulating resin layer, and comprises the intermediate resin layer is composed of any of the above bond plies, and the wiring layer is covered by the first adhesive layer or the second adhesive layer.

Advantages of the Invention

[0019] Since the bond ply of the present invention achieves both low dielectric tangent and dimensional stability, when applied to a circuit board such as a stripline for transmitting high-frequency signals in the GHz band (for example, 1 to 50 GHz), it can effectively reduce the transmission loss of high-frequency signals, and with excellent dimensional stability, it can improve reliability and yield.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram showing a cross-sectional structure of a bond ply according to an embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing the configuration of a stripline according to a preferred embodiment of the present invention. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described with reference to the drawings as appropriate. [Bond Ply] Figure 1 is a schematic diagram showing the cross-sectional structure of a bond ply according to one embodiment of the present invention. The bond ply 100 of this embodiment comprises a polyimide layer 10, a first adhesive layer 20A laminated on one side of the polyimide layer 10, and a second adhesive layer 20B laminated on the side of the polyimide layer 10 opposite to the first adhesive layer 20A. In other words, the bond ply 100 has a structure in which the first adhesive layer 20A, the polyimide layer 10, and the second adhesive layer 20B are laminated in this order.

[0022] The bond ply 100 of this embodiment satisfies the following conditions a to c. Condition a) The total thickness T1 of the bond ply 100 is within the range of 50 μm to 300 μm, and the ratio of the thickness T2 of the polyimide layer 10 to the total thickness T1 of the bond ply 100 (T2 / T1) is within the range of 0.2 to 0.9. If the overall thickness T1 of Bondply 100 is less than 50 μm, the overall thickness of the resin layer cannot be increased when applied to a stripline, resulting in insufficient reduction of transmission loss. If it exceeds 300 μm, there is a risk that the necessary flexibility for FPC cannot be guaranteed. From this perspective, the overall thickness T1 of Bondply 100 is more preferably within the range of 50 μm to 300 μm, or 50 μm to 150 μm.

[0023] Furthermore, if the ratio of the thickness T2 of the polyimide layer 10 to the total thickness T1 of the bond ply 100 (T2 / T1) is less than 0.2, dimensional stability decreases, and if it exceeds 0.9, the first adhesive layer 20A and the second adhesive layer 20B become too thin, making it difficult to ensure the necessary adhesion and circuit filling properties as a bonding sheet. From this viewpoint, a thickness ratio (T2 / T1) within the range of 0.2 to 0.9 is preferable.

[0024] Condition b) After drying at 80°C for 1 hour, the moisture absorption rate measured after 24 hours of constant temperature and humidity control at 23°C and 50%RH is 0.4% by weight or less. If the moisture absorption rate exceeds 0.4% by weight, the dielectric loss tangent of the entire bond ply 100 increases, and the transmission loss increases when applied to a stripline. From this viewpoint, it is preferable that the moisture absorption rate is 0.4% by weight or less. The overall moisture absorption rate of the bond ply 100 can be adjusted by the respective moisture absorption rates and thickness ratios of the polyimide layer 10, the first adhesive layer 20A, and the second adhesive layer 20B.

[0025] Condition c) The storage modulus of the first adhesive layer 20A and the second adhesive layer 20B at 50°C is independently 1800 MPa or less, and the maximum value of the storage modulus at 180-260°C is independently 800 MPa or less. The storage modulus of the first adhesive layer 20A and the second adhesive layer 20B, by having such storage moduli, can relieve internal stress when the bond ply 100 is heat-pressed and maintain dimensional stability after application to the strip line. If the storage moduli of the first adhesive layer 20A and the second adhesive layer 20B at 50°C exceed 1800 MPa, dimensional stability will be impaired. From this viewpoint, it is preferable that the storage moduli of the first adhesive layer 20A and the second adhesive layer 20B at 50°C be 1800 MPa or less.

[0026] Furthermore, by ensuring that the maximum storage modulus of the first adhesive layer 20A and the second adhesive layer 20B in the temperature range of 180°C to 260°C is 800 MPa or less, warping is less likely to occur even after the solder reflow process following circuit processing. It is preferable that the maximum storage modulus of the first adhesive layer 20A and the second adhesive layer 20B in the temperature range of 180°C to 260°C is 800 MPa or less.

[0027] The bond ply 100 of this embodiment is preferably further satisfied with the following condition d. Condition d) The dielectric loss tangent at 10 GHz, measured by a split-post dielectric resonator (SPDR) after 24 hours of humidity control under constant temperature and humidity conditions (normal state) of 23°C and 50% RH, is 0.004 or less. If the dielectric loss tangent of the entire Bondply 100 at 10 GHz exceeds 0.004, electrical signal loss is more likely to occur in the high-frequency signal transmission path when applied to a stripline. From this viewpoint, it is more preferable that the dielectric loss tangent of the entire Bondply 100 at 10 GHz be 0.003 or less. There is no particular lower limit to the dielectric loss tangent of the entire Bondply 100 at 10 GHz.

[0028] The bond ply 100 of this embodiment is preferably further satisfied with the following condition e. e) The tensile modulus of the polyimide layer 10 is 5.0 GPa or higher. The polyimide layer 10 having such a tensile modulus suppresses the influence of the thermal expansion coefficients of the first adhesive layer 20A and the second adhesive layer 20B, further improving dimensional stability after application to the stripline. Furthermore, by keeping the tensile modulus of the polyimide layer 10 within the above range, the thickness ratio of the polyimide layer 10 can be made relatively smaller, while the thickness ratio of the first adhesive layer 20A and the second adhesive layer 20B can be made larger, which is advantageous in terms of ensuring adhesion. It is more preferable that the tensile modulus of the polyimide layer 10 be 7.0 GPa or higher.

[0029] (Polyimide layer) The polyimide layer 10 preferably contains non-thermoplastic polyimide as the main component of the resin component, more preferably 70% by weight or more of the resin component, even more preferably 90% by weight or more of the resin component, and most preferably as the entirety of the resin component. The main component of the resin component means a component that is present in more than 50% by weight of the total resin component. Note that "non-thermoplastic polyimide" generally refers to polyimide that does not soften or become adhesive when heated, but in the present invention, the storage modulus at 30°C measured using a dynamic viscoelasticity measuring device (DMA) is 1.0 × 10⁻⁶. 9 The Pa is greater than or equal to 1.0 × 10⁻¹⁶, and the storage modulus at 350°C is 1.0 × 10⁻¹⁶. 8 This refers to polyimides with a storage modulus of Pa or higher. Furthermore, "thermoplastic polyimides" generally refer to polyimides whose glass transition temperature (Tg) can be clearly determined, but in this invention, the storage modulus at 30°C measured using DMA is 1.0 × 10⁻⁶. 9 The Pa is greater than or equal to 1.0 × 10⁻¹⁶, and the storage modulus at 350°C is 1.0 × 10⁻¹⁶. 8 This refers to polyimides with a Pa rating of less than 1.5. In this invention, the term "polyimide" also refers to resins made of polymers having imide groups in their molecular structure, including polyimides, polyamideimides, polyetherimides, polyesterimides, polysiloxaneimides, and polybenzimidazoleimides.

[0030] The non-thermoplastic polyimide constituting the polyimide layer 10 contains tetracarboxylic acid residues and diamine residues. In this invention, a tetracarboxylic acid residue refers to a tetravalent group derived from tetracarboxylic dianhydride, and a diamine residue refers to a divalent group derived from a diamine compound. When the raw materials, tetracarboxylic dianhydride and diamine compound, are reacted in approximately equimolar amounts, the types and molar ratios of tetracarboxylic acid residues and diamine residues contained in the polyimide can be made to correspond approximately to the types and molar ratios of the raw materials.

[0031] (tetracarboxylic acid residue) The non-thermoplastic polyimide constituting the polyimide layer 10 preferably contains tetracarboxylic acid residues derived from at least one of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) and 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ), as well as tetracarboxylic acid residues derived from at least one of pyromellitic acid dianhydride (PMDA) and 2,3,6,7-naphthalenetetracarboxylic acid dianhydride (NTCDA).

[0032] 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") readily form ordered structures in polymers, and by suppressing molecular motion, they can reduce dielectric loss tangent and hygroscopicity. BPDA residues can impart self-supporting properties to the gel film as polyamic acid in the polyimide precursor, but on the other hand, they tend to increase the CTE after imidation and lower the glass transition temperature, thereby reducing heat resistance. From this viewpoint, it is preferable to control the content of the non-thermoplastic polyimide constituting the polyimide layer 10 so that the total amount of BPDA residues and TAHQ residues is preferably in the range of 20 mol% to 60 mol%, more preferably in the range of 40 mol% to 50 mol%, relative to the total amount of tetracarboxylic acid residues. If the total amount of BPDA and TAHQ residues is less than 20 mol%, the formation of the polymer's ordered structure will be insufficient, resulting in reduced moisture resistance and insufficient reduction of the dielectric loss tangent. If it exceeds 60 mol%, there is a risk of increased CTE, increased change in in-plane retardation (RO), and reduced heat resistance.

[0033] Furthermore, tetracarboxylic acid residues derived from pyromellitic dianhydride (hereinafter also referred to as "PMDA residues") and tetracarboxylic acid residues derived from 2,3,6,7-naphthalenetetracarboxylic acid dianhydride (hereinafter also referred to as "NTCDA residues") possess rigidity, thereby enhancing in-plane orientation, keeping CTE low, and playing a role in controlling in-plane retardation (RO) and glass transition temperature. On the other hand, because PMDA residues have a small molecular weight, if their amount becomes too large, the imide group concentration of the polymer increases, the polar groups increase, and hygroscopicity increases, leading to an increase in dielectric loss tangent due to the influence of moisture within the molecular chain. Also, NTCDA residues, due to the highly rigid naphthalene skeleton, tend to make the film brittle and increase the elastic modulus. Therefore, the non-thermoplastic polyimide constituting the polyimide layer 10 preferably contains a total of 40 mol% to 80 mol%, more preferably 50 mol% to 60 mol%, and even more preferably 50 to 55 mol%, of the total tetracarboxylic acid residues. If the total of PMDA and NTCDA residues is less than 40 mol%, the CTE may increase or the heat resistance may decrease. If it exceeds 80 mol%, the imide group concentration of the polymer increases, the polar groups increase, the low hygroscopicity may be impaired, the dielectric loss tangent may increase, and the film may become brittle, reducing the self-supporting properties of the film.

[0034] Furthermore, it is preferable that the total amount of at least one BPDA residue and TAHQ residue, and at least one PMDA residue and NTCDA residue, be 80 mol% or more, preferably 90 mol% or more, relative to the total amount of tetracarboxylic acid residues.

[0035] Examples of tetracarboxylic acid residues other than the BPDA residue, TAHQ residue, PMDA residue, and NTCDA residue mentioned above, contained in the non-thermoplastic polyimide constituting the polyimide layer 10 include 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid anhydride, 2,3',3,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-, 2,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,3',3,4'-diphenyl ether tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyltetracarboxylic acid dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3.4-Dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-,1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic acid dianhydride, 2,3,6,7-anthracenetetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid Dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1,4,5,8-(or 2,3,6,7-)tetracarboxylic acid dianhydride, 2,3,8,9-,3,4,9,10-,4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, ethylene glycol Examples include tetracarboxylic acid residues derived from aromatic tetracarboxylic dianhydrides such as bisuanhydrotrimellitates.

[0036] (Diamine residue) The diamine residues included in the non-thermoplastic polyimide constituting the polyimide layer 10 are preferably diamine residues derived from a diamine compound represented by general formula (A1).

[0037] [ka]

[0038] In formula (A1), the linking group Z represents a single bond or -COO-, Y independently represents a monovalent hydrocarbon having 1 to 3 carbon atoms, which may be substituted with a halogen atom or a phenyl group, or an alkoxy group having 1 to 3 carbon atoms, or a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkenyl group, n represents an integer from 0 to 2, and p and q independently represent integers from 0 to 4. Here, "independently" means that in formula (A1), the multiple substituents Y and the integers p and q may be the same or different. In formula (A1), the hydrogen atoms in the two terminal amino groups may be substituted, for example, -NR2R3 (where R2 and R3 independently represent any substituent such as an alkyl group).

[0039] The diamine compound represented by general formula (A1) (hereinafter sometimes referred to as "diamine (A1)") is an aromatic diamine having one to three benzene rings. Because diamine (A1) has a rigid structure, it has the effect of conferring an ordered structure to the entire polymer. As a result, a polyimide with low gas permeability and low hygroscopicity can be obtained, and since the moisture content inside the molecular chain can be reduced, the dielectric loss tangent can be lowered. Here, a single bond is preferred as the linking group Z.

[0040] Examples of diamine (A1) include 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-n-propyl-4,4'-diaminobiphenyl (m-NPB), and 4-aminophenyl-4'-aminobenzoate (APAB). Among these, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) is the most preferred.

[0041] The non-thermoplastic polyimide constituting the polyimide layer 10 preferably contains 50 mol% or more, more preferably 80 mol% or more, and even more preferably 85 mol% or more of diamine residues derived from diamine (A1) relative to the total number of diamine residues. By using diamine (A1) in the above range, an ordered structure is easily formed throughout the polymer due to the rigid structure derived from the monomer, making it easier to obtain a non-thermoplastic polyimide with low gas permeability, low hygroscopicity, and low dielectric loss tangent. From this viewpoint, it is most preferable to contain residues derived from 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) in the range of 90 to 100 mol% relative to the total number of diamine residues.

[0042] Other diamine residues included in the non-thermoplastic polyimide constituting the polyimide layer 10 are not particularly limited as long as they are residues derived from diamine compounds used as raw materials for polyimide, but for example, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene)bisoxy] Bisaniline, 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)]benzophenone, 9,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 2,2-bis-[4-(4-aminophenoxy)phenyl ]Hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4' -[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl)ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,Examples include diamine residues derived from aromatic diamine compounds such as 5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, and 6-amino-2-(4-aminophenoxy)benzoxazole, as well as diamine residues derived from aliphatic diamine compounds such as dimer acid-type diamines in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl or amino groups.

[0043] In non-thermoplastic polyimides, the thermal expansion coefficient, storage modulus, tensile modulus, etc., can be controlled by selecting the types of tetracarboxylic acid residues and diamine residues, and the molar ratios of each when two or more tetracarboxylic acid residues or diamine residues are applied. Furthermore, in non-thermoplastic polyimides, if there are multiple polyimide structural units, they may exist as blocks or randomly, but random arrangement is preferable.

[0044] Furthermore, it is preferable to use aromatic groups for both the tetracarboxylic acid residues and diamine residues contained in the non-thermoplastic polyimide, as this can improve the dimensional accuracy of the polyimide film under high-temperature conditions.

[0045] (Synthesis of polyimides) Non-thermoplastic polyimides can be produced by reacting the above-mentioned acid anhydride and diamine in a solvent to produce a precursor resin, which is then cyclized by heating. For example, polyamic acid, a precursor of polyimide, can be obtained by dissolving the acid anhydride component and the diamine component in an organic solvent in approximately equimolar amounts and polymerizing them by stirring at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours. In the reaction, the reactants are dissolved in the organic solvent in a range of 5 to 30% by weight, preferably 10 to 20% by weight, to produce the precursor. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide, N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, trigrime, etc. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. Furthermore, while there are no particular restrictions on the amount of such organic solvent used, it is preferable to adjust the amount used so that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction is approximately 5 to 30% by weight.

[0046] In the synthesis of polyimides, the acid anhydrides and diamines can be used individually or in combination of two or more. By selecting the types of acid anhydrides and diamines, and the molar ratios of each when using two or more acid anhydrides or diamines, dielectric properties, thermal expansion properties, glass transition temperature, etc., can be controlled.

[0047] The synthesized precursor is usually advantageous to use as a reaction solvent solution, but can be concentrated, diluted, or replaced with other organic solvents as needed. Furthermore, the precursor generally exhibits excellent solvent solubility, which is advantageous for its use. The method for imidizing the precursor is not particularly limited; for example, heat treatment such as heating in the aforementioned solvent at a temperature in the range of 80 to 400°C for 1 to 24 hours is preferably employed.

[0048] The imide group concentration of the non-thermoplastic polyimide is preferably 37% by weight or less, more preferably 33% by weight or less, and even more preferably 32% by weight or less. Here, "imide group concentration" refers to the value obtained by dividing the molecular weight of the imide group (-(CO)2-N-) in the polyimide by the molecular weight of the entire polyimide structure. If the imide group concentration exceeds 37% by weight, the molecular weight of the resin itself decreases, and the low hygroscopicity also deteriorates due to the increase in polar groups. By selecting the above combination of acid anhydride and diamine compound, the orientation of molecules in the non-thermoplastic polyimide is controlled, thereby suppressing the increase in CTE associated with a decrease in imide group concentration and ensuring low hygroscopicity.

[0049] The weight-average molecular weight of the non-thermoplastic polyimide is preferably in the range of 10,000 to 400,000, and more preferably in the range of 50,000 to 350,000. If the weight-average molecular weight is less than 10,000, the strength of Bondply 100 tends to decrease. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity increases excessively, which tends to cause defects such as uneven film thickness and streaks during the coating process.

[0050] The thickness of the polyimide layer 10 is preferably in the range of 10 μm to 135 μm, and more preferably in the range of 12 μm to 50 μm, from the viewpoint of ensuring functions such as insulation and maintenance of mechanical strength as the base layer in Bondply 100, and also from the viewpoint of transportability when manufacturing Bondply 100. If the thickness of the polyimide layer 10 is less than the lower limit above, electrical insulation and handling will be insufficient, and if it exceeds the upper limit, productivity will decrease.

[0051] From the viewpoint of heat resistance, the polyimide layer 10 preferably has a glass transition temperature (Tg) of 280°C or higher. Having a glass transition temperature (Tg) of 280°C or higher allows for the maintenance of dimensional stability during heating processes such as soldering.

[0052] The thermal expansion coefficient of the polyimide layer 10 is preferably in the range of 1 ppm / K to 30 ppm / K, more preferably in the range of 1 ppm / K to 25 ppm / K, and even more preferably in the range of 15 ppm / K to 25 ppm / K, from the viewpoint of improving the dimensional stability of the bond ply 100 and suppressing warping.

[0053] Preferably, the dielectric loss tangent of the polyimide layer 10 is 0.006 or less, as measured by a split-post dielectric resonator (SPDR) after 24 hours of humidity control under constant temperature and humidity conditions (normal state) of 23°C and 50%RH. By keeping the dielectric loss tangent of the polyimide layer 10 at 0.006 or less at 10GHz, the dielectric loss tangent of the entire bond ply 100 can be reduced. If the dielectric loss tangent of the polyimide layer 10 at 10GHz exceeds 0.006, it becomes difficult to keep the dielectric loss tangent of the entire bond ply 100 low.

[0054] The polyimide layer 10 can be appropriately blended with optional components such as plasticizers, other curing resin components such as epoxy resins, curing agents, curing accelerators, coupling agents, fillers, and flame retardants.

[0055] (First adhesive layer, second adhesive layer) The first adhesive layer 20A and the second adhesive layer 20B are not particularly limited in their material, as long as condition c is satisfied, and may be independently composed of thermoplastic resin or thermosetting resin. Examples of such resins include polyimide resin, polyamide resin, epoxy resin, phenoxy resin, acrylic resin, polyurethane resin, styrene resin, polyester resin (including liquid crystal polyester resin), phenol resin, polysulfone resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene resin, polypropylene resin, silicone resin, polyetherketone resin, polyvinyl alcohol resin, polyvinyl butyral resin, styrene-maleimide copolymer, maleimide-vinyl compound copolymer, or (meth)acrylic copolymer, benzoxazine resin, bismaleimide resin, cyanate ester resin, and the like. From these, those that satisfy condition c can be selected or designed to satisfy condition c and used as the first adhesive layer 20A and the second adhesive layer 20B. When the first adhesive layer 20A and the second adhesive layer 20B are thermosetting resins, they may contain organic peroxides, curing agents, curing accelerators, etc., and if necessary, a curing agent and a curing accelerator, or a catalyst and a co-catalyst may be used in combination. The amount of curing agent, curing accelerator, catalyst, co-catalyst, and organic peroxide added, and whether or not they are added, should be determined within the range that condition c can be satisfied.

[0056] The resins constituting the first adhesive layer 20A and the second adhesive layer 20B are preferably resins containing polyimide as the main component of the resin component, more preferably 70% by weight or more of the resin component, even more preferably 90% by weight or more of the resin component, and most preferably all of the resin component contains polyimide. The main component of the resin component means a component that is present in more than 50% by weight of the total resin component. In order to satisfy condition c, a preferred polyimide used to form the first adhesive layer 20A and the second adhesive layer 20B is a polyimide (hereinafter sometimes referred to as "adhesive polyimide") that contains acid anhydride residues derived from tetracarboxylic anhydride components and diamine residues derived from diamine components, and also contains 50 mol% or more of diamine residues derived from a dimer amine composition in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, relative to the total diamine residues. In other words, adhesive polyimides are obtained by using a raw material containing 50 mol% or more of a dimeramine composition, mainly composed of dimeramines in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, relative to the total diamine components. By setting the content of diamine residues derived from the dimeramine composition to preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably in the range of 80 to 99 mol%, relative to the total diamine residues, condition c can be satisfied, and the relative permittivity and dielectric loss tangent can be reduced. That is, by including diamine residues derived from the dimeramine composition in the above amounts, it becomes possible to improve the thermocompression bonding properties by lowering the glass transition temperature (low Tg) of the polyimide and to relax internal stress by lowering the elastic modulus. Furthermore, if the content of diamine residues derived from the dimeramine composition is less than 50 mol%, the relative permittivity and dielectric loss tangent tend to increase as the number of polar groups contained in the polyimide increases relatively.

[0057] The dimer amine composition is a purified product that contains component (a) as the main component, while the amounts of components (b) and (c) are controlled.

[0058] (a) Dimer amine; (a) The dimer amine in component (a) refers to a diamine in which the two terminal carboxylic acid groups (-COOH) of a dimer acid are replaced with primary aminomethyl groups (-CH2-NH2) or amino groups (-NH2). Dimer acids are known dibasic acids obtained by the intermolecular polymerization reaction of unsaturated fatty acids, and their industrial production process is largely standardized in the industry. They are obtained by dimerizing unsaturated fatty acids with 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acids mainly consist of dibasic acids with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms, such as oleic acid, linoleic acid, and linolenic acid. However, depending on the degree of purification, they also contain arbitrary amounts of monomeric acids (18 carbon atoms), trimer acids (54 carbon atoms), and other polymeric fatty acids with 20 to 54 carbon atoms. Furthermore, although double bonds remain after the dimerization reaction, in this invention, dimer acids are also included in those obtained by further hydrogenation to reduce the degree of unsaturation. (a) The dimer amine of component (a) can be defined as a diamine compound obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0059] One characteristic of dimer amines is that they can impart properties derived from the dimer acid skeleton. Specifically, since dimer amines are macromolecules with a molecular weight of approximately 560-620 and are aliphatic, they can increase the molar volume of the molecule and relatively reduce the polar groups of polyimide. These characteristics of dimer acid-type diamines are thought to contribute to improving dielectric properties by reducing the relative permittivity and dielectric loss tangent while suppressing the decrease in the heat resistance of polyimide. Furthermore, because they have two freely moving hydrophobic chains with 7-9 carbon atoms and two chain-like aliphatic amino groups with lengths close to 18 carbon atoms, they not only give polyimide flexibility but can also create asymmetric or non-planar chemical structures, thus enabling the reduction of the dielectric constant of polyimide.

[0060] The dimer amine composition should preferably be purified by methods such as molecular distillation to increase the dimer amine content of component (a) to 96% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more. By increasing the dimer amine content of component (a) to 96% by weight or more, the broadening of the molecular weight distribution of the polyimide can be suppressed. Ideally, if technically possible, the entire dimer amine composition (100% by weight) should consist of dimer amine of component (a).

[0061] (b) Monoamine compounds obtained by substituting the terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group; Monobasic acid compounds with 10 to 40 carbon atoms are a mixture of monobasic unsaturated fatty acids with 10 to 20 carbon atoms derived from the raw materials of dimer acid, and monobasic acid compounds with 21 to 40 carbon atoms that are by-products during the production of dimer acid. Monoamine compounds are obtained by substituting the terminal carboxylic acid group of these monobasic acid compounds with a primary aminomethyl group or an amino group.

[0062] (b) The monoamine compound is a component that suppresses the increase in molecular weight of polyimide. During polymerization of polyamic acid or polyimide, the monofunctional amino group of the monoamine compound reacts with the terminal acid anhydride group of the polyamic acid or polyimide, thereby encapsulating the terminal acid anhydride group and suppressing the increase in molecular weight of the polyamic acid or polyimide.

[0063] (c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group in the range of 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the dimer amines mentioned above); Polybasic acid compounds having hydrocarbon groups with 41 to 80 carbon atoms are polybasic acid compounds mainly composed of tribasic acid compounds with 41 to 80 carbon atoms, which are by-products of dimer acid production. They may also contain polymerized fatty acids other than dimer acid with 41 to 80 carbon atoms. Amine compounds are obtained by substituting the terminal carboxylic acid groups of these polybasic acid compounds with primary aminomethyl groups or amino groups.

[0064] (c) The amine compounds in component (c) are components that promote an increase in the molecular weight of polyimide. Trifunctional or higher amino groups, mainly triamine compounds derived from trimer acids, react with the terminal acid anhydride groups of polyamic acid or polyimide, causing a rapid increase in the molecular weight of polyimide. In addition, amine compounds derived from polymerized fatty acids other than dimer acids with 41 to 80 carbon atoms also increase the molecular weight of polyimide and cause gelation of polyamic acid or polyimide.

[0065] When quantifying each component using gel permeation chromatography (GPC), samples of the dimer amine composition treated with acetic anhydride and pyridine are used to facilitate the identification of the peak start, peak top, and peak end of each component, and cyclohexanone is used as an internal standard. Using these prepared samples, each component is quantified by the area percentage of the GPC chromatogram. The peak start and peak end of each component are defined as the minimum values ​​of each peak curve, and the area percentage of the chromatogram can be calculated based on these values.

[0066] Furthermore, the dimer amine composition should have a total area percentage of components (b) and (c) of 4% or less, preferably less than 4%, in the chromatogram obtained by GPC measurement. By keeping the total of components (b) and (c) at 4% or less, the broadening of the molecular weight distribution of the polyimide can be suppressed.

[0067] Furthermore, the area percentage of the chromatogram of component (b) is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. By keeping it within this range, the decrease in the molecular weight of the polyimide can be suppressed, and the range of molar ratios of the tetracarboxylic anhydride component and the diamine component can be broadened. Note that component (b) does not have to be included in the dimer amine composition.

[0068] Furthermore, the area percentage of the chromatogram of component (c) is 2% or less, preferably 1.8% or less, and more preferably 1.5% or less. By keeping it within this range, a rapid increase in the molecular weight of the polyimide can be suppressed, and furthermore, the increase in the dielectric loss tangent of the resin film over a wide frequency range can be suppressed. Note that component (c) does not necessarily have to be included in the dimer amine composition.

[0069] Furthermore, when the ratio of the area percentages of the chromatograms of components (b) and (c) (b / c) is 1 or greater, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) is preferably 0.97 or greater and less than 1.0. By using such a molar ratio, it becomes easier to control the molecular weight of the polyimide.

[0070] Furthermore, if the ratio (b / c) of the area percentages of the chromatograms of components (b) and (c) is less than 1, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) is preferably 0.97 or more and 1.1 or less. By using such a molar ratio, it becomes easier to control the molecular weight of the polyimide.

[0071] Commercially available dimer amine compositions are available, and it is preferable to purify them to reduce components other than dimer amine in component (a), for example, it is preferable to have component (a) at 96 area % or more. There are no particular restrictions on the purification method, but known methods such as distillation and precipitation purification are preferred. Examples of commercially available dimer amine compositions include PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

[0072] The synthesis of adhesive polyimides can be carried out in accordance with the method described above for non-thermoplastic polyimides.

[0073] Adhesive polyimides, when they have a ketone group in their molecule, can form a crosslinked structure by reacting the ketone group with the amino group of an amino compound having at least two primary amino groups as functional groups (hereinafter sometimes referred to as "crosslinking amino compound") to form a C=N bond. A polyimide with such a crosslinked structure (hereinafter sometimes referred to as "crosslinked polyimide") is an example of an application of adhesive polyimide and is a preferred form. The heat resistance of the adhesive polyimide can be improved by forming a crosslinked structure. Preferred tetracarboxylic dianhydrides for forming adhesive polyimides having a ketone group include, for example, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and examples of diamine compounds include aromatic diamines such as 4,4'-bis(3-aminophenoxy)benzophenone (BABP) and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB). For the purpose of forming a crosslinked structure, it is preferable to react the above-mentioned adhesive polyimide, which preferably contains 50 mol% or more, more preferably 60 mol% or more, of BTDA residues derived from BTDA relative to all tetracarboxylic acid residues, with a crosslinking amino compound. In this invention, "BTDA residue" refers to a tetravalent group derived from BTDA.

[0074] Examples of amino compounds for crosslinking include (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form crosslinked structures even at room temperature, raising concerns about the storage stability of the varnish, while aromatic diamines require high temperatures to form crosslinked structures. Thus, using dihydrazide compounds allows for both storage stability of the varnish and a reduction in curing time. Examples of dihydrazide compounds include dihydrazide oxalate, dihydrazide malonic acid, dihydrazide succinate, dihydrazide glutarate, dihydrazide adipic acid, dihydrazide pimelic acid, dihydrazide suberic acid, dihydrazide azelaic acid, dihydrazide sebacate, dihydrazide dodecanediic acid, dihydrazide maleate, dihydrazide fumarate, and diglyceride. Dihydrazide compounds such as cholic acid dihydrazide, tartrate dihydrazide, malate dihydrazide, phthalate dihydrazide, isophthalate dihydrazide, terephthalate dihydrazide, 2,6-naphthoate dihydrazide, 4,4-bisbenzene dihydrazide, 1,4-naphthoate dihydrazide, 2,6-pyridinedioate dihydrazide, and itaconic acid dihydrazide are preferred. These dihydrazide compounds may be used individually or in combination of two or more types.

[0075] Furthermore, amino compounds such as (I) dihydrazide compounds, (II) aromatic diamines, and (III) aliphatic amines can be used in combination of two or more types, even across categories, for example, a combination of (I) and (II), a combination of (I) and (III), or a combination of (I), (II), and (III).

[0076] Furthermore, from the viewpoint of making the network structure formed by crosslinking with the crosslinking amino compound denser, the crosslinking amino compound used in the present invention preferably has a molecular weight (weight-average molecular weight if the crosslinking amino compound is an oligomer) of 5,000 or less, more preferably 90 to 2,000, and even more preferably 100 to 1,500. Among these, a crosslinking amino compound having a molecular weight of 100 to 1,000 is particularly preferred. When the molecular weight of the crosslinking amino compound is less than 90, only one amino group of the crosslinking amino compound forms a C=N bond with the ketone group of the adhesive polyimide, and the area around the remaining amino groups becomes sterically bulky, making it difficult for the remaining amino groups to form C=N bonds.

[0077] When crosslinking ketone groups in adhesive polyimide with a crosslinking amino compound, the crosslinking amino compound is added to a resin solution containing adhesive polyimide to cause a condensation reaction between the ketone groups in the adhesive polyimide and the primary amino groups of the crosslinking amino compound. This condensation reaction causes the resin solution to harden into a cured product. In this case, the amount of crosslinking amino compound added can be 0.004 moles to 1.5 moles, preferably 0.005 moles to 1.2 moles, more preferably 0.03 moles to 0.9 moles, and most preferably 0.04 moles to 0.6 moles of primary amino groups per mole of ketone groups. When the amount of crosslinking amino compound added is such that the total amount of primary amino groups is less than 0.004 moles per mole of ketone groups, the crosslinking by the crosslinking amino compound is insufficient, and the heat resistance after curing tends to be poor. When the amount of crosslinking amino compound added exceeds 1.5 moles, the unreacted crosslinking amino compound acts as a thermoplastic, which tends to reduce the heat resistance of the adhesive layer.

[0078] The conditions for the condensation reaction for crosslinking are not particularly limited, as long as the ketone groups in the adhesive polyimide react with the primary amino groups of the crosslinking amino compound to form imine bonds (C=N bonds). The temperature for the heating condensation is preferably in the range of 120 to 220°C, and more preferably in the range of 140 to 200°C, for reasons such as releasing the water produced by the condensation from the system or simplifying the condensation step when the heating condensation reaction is carried out immediately after the synthesis of the adhesive polyimide. The reaction time is preferably about 30 minutes to 24 hours. The endpoint of the reaction is 1670 cm⁻¹, for example, by measuring the infrared absorption spectrum using a Fourier transform infrared spectrophotometer (commercially available: JASCO FT / IR620). -1 A decrease or disappearance of absorption peaks originating from ketone groups in the nearby polyimide resin, and at 1635 cm⁻¹. -1 This can be confirmed by the appearance of absorption peaks originating from nearby imine groups.

[0079] The thermal condensation of the ketone group of the adhesive polyimide and the primary amino group of the above crosslinking amino compound is, for example, (1) A method of adding an amino compound for crosslinking and heating following the synthesis (imidization) of adhesive polyimide. (2) A method in which an excess amount of amino compound is pre-charged as the diamine component, and following the synthesis (imidation) of adhesive polyimide, the remaining amino compound that does not participate in imidation or amidation is used as a crosslinking amino compound and heated together with the adhesive polyimide. Or, (3) A method of heating an adhesive polyimide composition to which the above-mentioned crosslinking amino compound has been added, after it has been processed into a predetermined shape (for example, after being applied to any substrate or after being formed into a film), This can be done by means of, for example.

[0080] While an example of a crosslinked polyimide, formed by the creation of imine bonds to impart heat resistance to adhesive polyimides, was given, the method is not limited to this. As a curing method for polyimides, it is also possible to cure them by incorporating compounds having unsaturated bonds, such as epoxy resins, epoxy resin curing agents, maleimides, activated ester resins, and resins with a styrene skeleton.

[0081] The first adhesive layer 20A and the second adhesive layer 20B each have a glass transition temperature (Tg) of 180°C or less, preferably within the range of 160°C or less. By setting the Tg of the first adhesive layer 20A and the second adhesive layer 20B to 180°C or less, thermocompression bonding at low temperatures becomes possible, thereby mitigating internal stress generated during lamination and suppressing dimensional changes after circuit processing. If the Tg of the first adhesive layer 20A and the second adhesive layer 20B exceeds 180°C, the temperature required for bonding by interposing them between insulating resin layers for application to a stripline becomes high, which may impair the dimensional stability of the stripline.

[0082] Preferably, the first adhesive layer 20A and the second adhesive layer 20B have a dielectric loss tangent of 0.004 or less at 10 GHz, as measured by a split-post dielectric resonator (SPDR) after 24 hours of conditioning under constant temperature and humidity conditions (normal state) of 23°C and 50% RH. By having a dielectric loss tangent of 0.004 or less at 10 GHz for the first adhesive layer 20A and the second adhesive layer 20B, the dielectric loss tangent of the entire bond ply 100 can be reduced. If the dielectric loss tangent of the polyimide layer 10 at 10 GHz exceeds 0.004, it becomes difficult to keep the dielectric loss tangent of the entire bond ply 100 low.

[0083] The first adhesive layer 20A and the second adhesive layer 20B may contain optional components such as plasticizers, other curing resin components such as epoxy resins, curing agents, curing accelerators, coupling agents, fillers, and flame retardants as appropriate.

[0084] Bondply 100 can be manufactured, for example, by method 1 or method 2 below.

[0085] [Method 1] A polyimide film corresponding to the polyimide layer 10 that makes up Bondply 100, and adhesive films corresponding to the first adhesive layer 20A and the second adhesive layer 20B are prepared separately. Next, the polyimide film is placed between the two adhesive films, and by thermocompression bonding at a temperature exceeding the glass transition temperature of the resins constituting the first adhesive layer 20A and the second adhesive layer 20B, for example, Bondply 100 with a three-layer laminated structure can be manufactured.

[0086] [Method 2] First, a polyimide film corresponding to the polyimide layer 10 is prepared by a conventional method, and a resin solution constituting the first adhesive layer 20A is applied to one side of the film to a predetermined thickness. The coated film is then heated to form the first adhesive layer 20A. Next, a resin solution constituting the second adhesive layer 20B is applied to the other side of the polyimide film to a predetermined thickness. The coated film is then heated and dried to form the second adhesive layer 20B. In this way, a bond ply 100 with a three-layer laminated structure can be manufactured.

[0087] The polyimide films and adhesive films used in methods 1 and 2 described above can be manufactured, for example, by applying and drying a resin solution onto any support substrate, and then peeling it off the support substrate to form a film. Furthermore, there are no particular limitations on the method of applying the resin solution onto the support substrate or polyimide film; for example, it can be applied using a coater such as a comma, die, knife, or lip.

[0088] [Circuit board] Bondply 100 is useful primarily as a circuit board material for FPCs, rigid-flex circuit boards, and the like. For example, a multilayer circuit board can be manufactured by preparing a metal-clad laminate having an insulating resin layer and a metal layer, or by preparing a circuit board in which a wiring layer is formed by processing the metal layer of the metal-clad laminate into a pattern by a conventional method, and then sandwiching Bondply 100 between two or more metal-clad laminates and / or circuit boards and heat-pressing them together to form a single unit. One example of such a circuit board is a stripline used as a high-frequency transmission line.

[0089] (Strip line) Figure 2 is a schematic diagram illustrating the cross-sectional structure of a stripline as a preferred embodiment of the circuit board of the present invention. The stripline 200 shown in Figure 2 comprises a first metal layer 30A, a first insulating resin layer 40A consisting of one or more layers laminated on one side of the first metal layer 30A, and a wiring layer 50 provided in contact with the first insulating resin layer 40A. Here, the first metal layer 30A, the first insulating resin layer 40A, and the wiring layer 50 form a first laminate 60A. Furthermore, the stripline 200 includes a second metal layer 30B and a second insulating resin layer 40B consisting of one or more layers laminated on one side of the second metal layer 30B. Here, the second metal layer 30B and the second insulating resin layer 40B form a second laminate 60B. Furthermore, the stripline 200 includes an intermediate resin layer 101 that is laminated interposed between the first insulating resin layer 40A and the second insulating resin layer 40B.

[0090] The stripline 200 has an intermediate resin layer 101 formed by bond ply 100. That is, an intermediate resin layer 101 made of bond ply 100 is interposed between the first laminate 60A and the second laminate 60B, with the first adhesive layer 20A of bond ply 100 in contact with the first insulating resin layer 40A and the wiring layer 50 of the first laminate 60A, and the second adhesive layer 20B of bond ply 100 in contact with the second insulating resin layer 40B of the second laminate 60B. The first adhesive layer 20A of bond ply 100 covers the wiring layer 50. In other words, the wiring layer 50, which is formed protruding from the first insulating resin layer 40A, is inserted and embedded in the first adhesive layer 20A.

[0091] In the stripline 200, the first metal layer 30A and the second metal layer 30B function as a ground layer or a shield layer. In the stripline 200, the wiring layer 50 is patterned and functions as a signal line. There are no particular restrictions on the material of the first metal layer 30A, the second metal layer 30B and the wiring layer 50, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese and their alloys. Among these, copper or copper alloys are particularly preferred. If copper foil is used, it may be rolled copper foil or electrolytic copper foil.

[0092] In the stripline 200, the first insulating resin layer 40A and the second insulating resin layer 40B are not particularly limited as long as they are made of an electrically insulating resin, and may be independently made of a thermoplastic resin or a thermosetting resin. Examples of such resins include polyimide resin, polyamide resin, epoxy resin, phenoxy resin, acrylic resin, polyurethane resin, styrene resin, polyester resin (including liquid crystal polyester resin), phenol resin, polysulfone resin, polyethersulfone resin, polyphenylene sulfide resin, polyethylene resin, polypropylene resin, silicone resin, polyetherketone resin, polyvinyl alcohol resin, polyvinyl butyral resin, styrene-maleimide copolymer, maleimide-vinyl compound copolymer, or (meth)acrylic copolymer, benzoxazine resin, bismaleimide resin, cyanate ester resin, and the like. Furthermore, the first insulating resin layer 40A and the second insulating resin layer 40B are not limited to single layers, but may be laminated with multiple resin layers.

[0093] The thickness and thickness ratio of each layer constituting the stripline 200 can be set as appropriate according to the purpose, but by including Bondply 100, which has excellent dimensional stability, low hygroscopicity, and low dielectric loss tangent, it is possible to improve reliability based on high dimensional stability and suppress transmission loss of high-frequency signals. In particular, in the stripline 200, the first adhesive layer 20A is filled so as to cover the periphery of the wiring layer 50, and with this characteristic structure, when a resin material with a low dielectric loss tangent (for example, the above-mentioned adhesive polyimide) is used as the first adhesive layer 20A, an excellent effect of reducing transmission loss can be expected. Furthermore, by including Bondply 100 in the stripline 200, unlike when using a bonding sheet, problems such as damage such as abrasion and gouging during laser processing and resin leakage during the soldering process can be avoided.

[0094] The stripline 200 can be manufactured by manufacturing the first laminate 60A and the second laminate 60B separately by conventional methods and bonding them together using a separately prepared bond ply 100. Specifically, the first insulating resin layer 40A and the wiring layer 50 of the first laminate 60A are positioned opposite the first adhesive layer 20A of the bond ply 100, and the second insulating resin layer 40B of the second laminate 60B is positioned opposite the second adhesive layer 20B of the bond ply 100. The stripline can then be manufactured by, for example, thermocompressing them at a temperature exceeding the glass transition temperature of the resins constituting the first adhesive layer 20A and the second adhesive layer 20B of the bond ply 100. [Examples]

[0095] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way by these examples. In the following examples, unless otherwise specified, various measurements and evaluations are performed as described below.

[0096] [Method for measuring amine value] Weigh approximately 2 g of dimer amine composition into a 200-250 mL Erlenmeyer flask. Using phenolphthalein as an indicator, add 0.1 mol / L ethanolic potassium hydroxide solution dropwise until the solution turns pale pink, then dissolve in approximately 100 mL of neutralized butanol. Add 3-7 drops of phenolphthalein solution and titrate with 0.1 mol / L ethanolic potassium hydroxide solution while stirring until the sample solution turns pale pink. Add 5 drops of bromophenol blue solution and titrate with 0.2 mol / L hydrochloric acid / isopropanol solution while stirring until the sample solution turns yellow. The amine value is calculated using the following formula (1). Amine value = {(V2×C2)-(V1×C1)}×M KOH / m ···(1) Here, the amine value is expressed as a value in mg-KOH / g, M KOHThe molecular weight of potassium hydroxide is 56.1. V and C represent the volume and concentration of the solution used in the titration, respectively, and the subscripts 1 and 2 represent a 0.1 mol / L ethanolic potassium hydroxide solution and a 0.2 mol / L hydrochloric acid / isopropanol solution, respectively. Furthermore, m is the sample weight in grams.

[0097] [Calculation of area percentage for GPC and chromatogram] (a) Dimer amine (b) Monoamine compounds obtained by substituting the terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group. (c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group in the range of 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the dimer amines mentioned above).

[0098] For GPC analysis, a 100 mg solution of 20 mg of dimer amine composition was pretreated with 200 μL of acetic anhydride, 200 μL of pyridine, and 2 mL of THF. This solution was then diluted with 10 mL of THF (containing 1000 ppm of cyclohexanone) to prepare the sample. The prepared sample was measured using a Tosoh Corporation HLC-8220GPC under the following conditions: column: TSK-gel G2000HXL, G1000HXL, flow rate: 1 mL / min, column (oven) temperature: 40°C, injection volume: 50 μL. Cyclohexanone was used as a standard substance to correct for efflux time.

[0099] At this time, the peak top of the cyclohexanone main peak is adjusted so that the retention time is from 27 minutes to 31 minutes, and the time from the peak start to the peak end of the cyclohexanone main peak is 2 minutes, and the peak top of the main peak excluding the cyclohexanone peak is from 18 minutes to 19 minutes, and the time from the peak start to the peak end of the main peak excluding the cyclohexanone peak is from 2 minutes to 4 minutes 30 seconds, under the conditions that the above components (a) to (c) are as follows: (a) The component represented by the main peak; (b) Components represented by GPC peaks detected at times later than the minimum retention time at the main peak; (c) Components represented by GPC peaks detected earlier than the minimum retention time at the main peak; Detected.

[0100] [Measurement of weight-average molecular weight (Mw)] The weight-average molecular weight was measured using gel permeation chromatography (HLC-8220GPC, manufactured by Tosoh Corporation). Polystyrene was used as the standard substance, and tetrahydrofuran (THF) was used as the developing solvent.

[0101] [Viscosity measurement] Viscosity was measured at 25°C using an E-type viscometer (Brookfield, product name: DV-II+Pro). The rotation speed was set so that the torque was between 10% and 90%, and the value was read after 2 minutes had elapsed since the start of measurement, when the viscosity had stabilized.

[0102] [Measurement of the coefficient of thermal expansion (CTE)] A 3mm x 20mm polyimide film was heated from 30°C to 265°C at a constant rate of 20°C / min while applying a 5.0g load using a thermomechanical analyzer (Bruker, product name: 4000SA). After holding the film at this temperature for 10 minutes, it was cooled at a rate of 5°C / min, and the average thermal expansion coefficient from 250°C to 100°C was determined.

[0103] [Measurement of relative permittivity (Dk) and dielectric loss tangent (Df)] The relative permittivity and dielectric loss tangent of resin sheets (adhesive films, resin laminates) at 10 GHz were measured using a vector network analyzer (Agilent, product name: E8363C) and an SPDR resonator. The materials used for measurement were left standing for 24 hours under conditions of temperature: 20-26°C and humidity: 45-55%RH.

[0104] [Measurement of storage modulus and glass transition temperature (Tg)] The sample was cut into 5mm x 20mm sections and heated stepwise from 30°C to 400°C at a heating rate of 4°C / min using a dynamic viscoelasticity analyzer (DMA: UBM Corporation, product name: E4000F), with measurements taken at a frequency of 11Hz. The maximum temperature at which the Tanδ value was maximized during measurement was defined as Tg.

[0105] [Measurement of moisture absorption rate] A sample of A4 size (TD: 210 mm × MD: 297 mm) (polyimide film or bond ply) was dried in a hot air oven at 80°C for 1 hour, and its weight after drying was measured and taken as the dry weight (W1). The sample with the measured dry weight was then allowed to absorb moisture for 24 hours under constant temperature and humidity conditions of 23°C and 50% RH, and its weight after absorption was measured and taken as the weight after absorption (W2). The moisture absorption rate was calculated by substituting the measured weight into the following formula. Moisture absorption rate (weight %)=[(W2-W1) / W1]×100

[0106] [Measurement of dimensional change rate] Electrolytic copper foil (manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., product name: T49A-DS-HD2, thickness: 12 μm) is superimposed on both sides of the bond ply. For adhesive films with a glass transition temperature of less than 160°C, the bond ply is hot-pressed for 40 minutes at a temperature of 160°C and a pressure of 4 MPa. For adhesive films with a glass transition temperature of 300°C or higher, the bond ply is hot-pressed for 40 minutes at a temperature of 390°C and a pressure of 4 MPa to obtain a copper foil-coated bond ply. After obtaining a 150 mm square test piece, a dry film resist is exposed and developed at 100 mm intervals to form a target for position measurement. The dimensions before etching (normal state) are measured in an atmosphere of 23 ± 2°C and 50 ± 5% relative humidity. Then, the copper other than the target on the test piece is removed by etching (liquid temperature 40°C or less, time within 10 minutes). After standing for 24 ± 4 hours in an atmosphere of 23 ± 2°C and 50 ± 5% relative humidity, the dimensions after etching are measured. The dimensional change rates relative to the normal state were calculated for three locations in both the MD direction (longitudinal direction) and the TD direction (width direction), and the average value of these values ​​was used as the dimensional change rate after etching. The dimensional change rate after etching was calculated using the following formula.

[0107] Dimensional change rate after etching (%) = [(BA) / A] × 100 A; Distance between targets before etching B; Distance between targets after etching

[0108] The abbreviations used in this example indicate the following compounds. PMDA: Pyromellitic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride BTDA:3,3',4,4'-benzophenonetetracarboxylic dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis(4-aminophenoxy)benzene p-PDA: Paraphenylenediamine BAPP: 2,2-Bis[4-(4-aminophenoxy)phenyl]propane APB: 1,3-Bis(3-aminophenoxy)benzene NMP:N-methyl-2-pyrrolidone DMAc: N,N-dimethylacetamide DDA: A 36-carbon aliphatic diamine (manufactured by Croda Japan Co., Ltd., trade name: PRIAMINE 1074, distilled and purified; amine value: 210 mg KOH / g; mixture of cyclic and chain-like dimer amines; component (a): 97.9%, component (b): 0.3%, component (c): 1.8%) N-12: Dodecane dioxide dihydrazide OP935: Organic aluminum phosphinate salt (manufactured by Clariant Japan, product name: Exolit OP935) In the above DDA, the "%" for component (a), component (b), and component (c) represents the area percentage of the chromatogram measured by GPC. Furthermore, the molecular weight of the above DDA was calculated using the following formula. Molecular weight = 56.1 × 2 × 1000 / Amine value

[0109] (Synthesis Example 1) Under a nitrogen atmosphere, 12.745 g of m-TB (0.0599 mol), 1.947 g of TPE-R (0.0066 mol), and an amount of DMAc such that the solid content concentration after polymerization was 15% by weight were added to the reaction bed and stirred at room temperature to dissolve. Next, 11.447 g of PMDA (0.0525 mol) and 3.86 g of BPDA (0.0131 mol) were added, and the polymerization reaction was carried out by continuing to stir at room temperature for 3 hours to prepare polyamic acid solution 1 (viscosity: 16,500 cps).

[0110] (Synthesis Example 2) Under a nitrogen atmosphere, 13.780 g of m-TB (0.0643 mol) and an amount of DMAc such that the solid content concentration after polymerization would be 15% by weight were added to the reaction bed and stirred at room temperature to dissolve. Next, 6.903 g of PMDA (0.0317 mol) and 9.317 g of BPDA (0.0317 mol) were added, and the polymerization reaction was carried out by continuing to stir at room temperature for 3 hours to prepare polyamic acid solution 2 (viscosity: 12,500 cps).

[0111] (Synthesis Example 3) Under a nitrogen atmosphere, 7.715 g of m-TB (0.0363 mol), 3.694 g of p-PDA (0.0363 mol), DMAc in an amount that results in a solid content concentration of 15% by weight after polymerization, 7.797 g of PMDA (0.0375 mol), and 10.524 g of BPDA (0.0375 mol) were added to the reaction bed. The mixture was then stirred at room temperature for 3 hours to carry out the polymerization reaction and prepare polyamic acid solution 3 (viscosity: 9,600 cps).

[0112] (Synthesis Example 4) Under a nitrogen atmosphere, 9.061 g of p-PDA (0.0830 mol) and an amount of DMAc such that the solid content concentration after polymerization would be 15% by weight were added to the reaction bed and stirred at room temperature to dissolve. Next, 8.9112 g of PMDA (0.0409 mol) and 12.0275 g of BPDA (0.0409 mol) were added, and the polymerization reaction was carried out by continuing to stir at room temperature for 3 hours to prepare polyamic acid solution 4 (viscosity: 11,000 cps).

[0113] (Synthesis Example 5) A 500 mL four-necked flask equipped with a nitrogen inlet tube, stirrer, thermocouple, Dean-Stark trap, and condenser was charged with 44.92 g of BTDA (0.139 mol), 75.08 g of DDA (0.141 mol), 168 g of NMP, and 112 g of xylene. The mixture was stirred at 40°C for 30 minutes to prepare a polyamic acid solution. This polyamic acid solution was heated to 190°C and stirred for 4 hours, and the distilled water and xylene were removed from the system. The mixture was then cooled to 100°C, 112 g of xylene was added and stirred, and the mixture was further cooled to 30°C to complete the imidation process and prepare polyimide solution 5 (solids content: 29.5% by weight, weight-average molecular weight: 75,700).

[0114] (Synthesis Example 6) A 500 mL four-necked flask equipped with a nitrogen inlet tube, stirrer, thermocouple, Dean-Stark trap, and condenser was charged with 47.67 g of BTDA (0.148 mol), 46.3969 g of DDA (0.085 mol), 16.601 g of APB (0.05679 mol), 155 g of NMP, and 103 g of xylene. The mixture was stirred at 40°C for 30 minutes to prepare a polyamic acid solution. This polyamic acid solution was heated to 190°C and stirred for 4 hours, and the distilled water and xylene were removed from the system. The mixture was then cooled to 100°C, 112 g of xylene was added and stirred, and the mixture was further cooled to 30°C to complete the imidation process and prepare polyimide solution 6 (solids content: 29.5% by weight, weight-average molecular weight: 85,200).

[0115] (Synthesis Example 7) Under a nitrogen atmosphere, 18.574 g of BAPP (0.0453 mol), DMAc in an amount that results in a solid content concentration of 15% by weight after polymerization, and 9.7354 g of PMDA (0.0446 mol) were added to the reaction bed. The polymerization reaction was then carried out by stirring at room temperature for 3 hours to prepare polyamic acid solution 7 (viscosity: 5,300 cps).

[0116] (Example 1) A polyamic acid solution 1 was uniformly applied to a copper foil 1 (electrolytic copper foil, thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) so that the thickness after curing was approximately 50 μm. The solution was then heated and dried at 120°C to remove the solvent. Subsequently, stepwise heat treatment was performed from 120°C to 360°C to complete the imidization and prepare a single-sided metal-clad laminate 1. The copper foil 1 of the single-sided metal-clad laminate 1 was etched off using an aqueous ferric chloride solution to prepare a polyimide film 1 (thickness: 50 μm, CTE: 12 ppm / K, Dk: 3.3, Df: 0.0056, moisture absorption rate: 0.77 wt%, Tg: 378°C).

[0117] (Example 2) Polyimide film 2 (thickness: 50 μm, CTE: 16.4 ppm / K, Dk: 3.4, Df: 0.0036, moisture absorption rate: 0.63 wt%, Tg: 332°C) was prepared in the same manner as in Preparation Example 1, except that polyamic acid solution 2 was used.

[0118] (Production Example 3) A polyimide film 3 (thickness: 50 μm, CTE: 22.4 ppm / K, Dk: 3.6, Df: 0.0051, moisture absorption rate: 0.65 wt%) was prepared in the same manner as in Production Example 1, except that polyamic acid solution 3 was used.

[0119] (Production Example 4) A polyimide film 4 (thickness: 50 μm, CTE: 15.8 ppm / K, Dk: 3.8, Df: 0.0122, moisture absorption rate: 1.66 wt%, Tg > 400°C) was prepared in the same manner as in Production Example 1, except that polyamic acid solution 4 was used.

[0120] (Production Example 5) A polyimide film 5 (thickness: 25 μm, CTE: 11.4 ppm / K, Dk: 3.4, Df: 0.0038, moisture absorption rate: 0.64 wt%) was prepared in the same manner as in Production Example 1, except that polyamic acid solution 2 was used and the thickness after curing was adjusted to be about 25 μm.

[0121] (Production Example 6) 1.8 g of N-12 (0.0036 mol) and 12.5 g of OP935 were added to 169.49 g (50 g as solid content) of polyimide solution 5, and 6.485 g of NMP and 19.345 g of xylene were added and diluted to prepare polyimide varnish 1.

[0122] Polyimide varnish 1 was applied to the silicone-treated surface of a release substrate 1 (length × width × thickness = 320 mm × 240 mm × 25 μm) so that the thickness after drying would be 50 μm, then heated and dried at 80°C for 15 minutes, and peeled off from the release substrate 1 to prepare an adhesive film 1 (thickness: 50 μm, CTE: 113 ppm / K, Dk: 2.7, Df: 0.0024). The storage elastic modulus of the adhesive film 1 at 50°C after curing and the maximum value of the storage elastic modulus in the steep gradient temperature range of 180°C to 260°C were 5.0×10 2 MPa and 3.0 MPa, respectively. The glass transition temperature of the adhesive film 1 was 54°C.

[0123] (Example 7) Polyimide varnish 2 was prepared by adding 1.8 g of N-12 (0.0036 mol) and 12.5 g of OP935 to 169.49 g (50 g as solids) of polyimide solution 6, and then diluting it with 6.485 g of NMP and 19.345 g of xylene.

[0124] Adhesive film 2 (thickness: 50 μm, CTE: 78 ppm / K, Dk: 2.7, Df: 0.0028) was prepared in the same manner as in Fabrication Example 6, except that polyimide varnish 2 was used. The maximum storage modulus of adhesive film 2 at 50°C after curing and in the steep temperature range of 180°C to 260°C were 15.0 × 10⁻⁶, respectively. 2 The pressure was 12.0 MPa. The glass transition temperature of adhesive film 2 was 120°C.

[0125] (Example 8) A polyamic acid solution 7 was uniformly applied to copper foil 1 to a thickness of approximately 50 μm after curing, and then heated and dried at 120°C to remove the solvent. Subsequently, stepwise heat treatment was performed from 120°C to 360°C to complete the imidization and prepare a single-sided metal-clad laminate 2. The copper foil 1 of the single-sided metal-clad laminate 2 was etched off using an aqueous ferric chloride solution to prepare an adhesive film 3 (thickness: 50 μm, CTE: 58 ppm / K, Dk: 3.4, Df: 0.0059). The maximum storage modulus of adhesive film 3 at 50°C after curing and in the steep temperature gradient range of 180°C to 260°C were 29.0 × 10⁻⁶, respectively. 2 MPa, 21.0 × 10 2 The pressure was MPa. Furthermore, the glass transition temperature of adhesive film 3 was 326°C.

[0126] (Example 9) A polyimide film 6 (thickness: 12 μm, CTE: 28.6 ppm / K, Dk: 3.4, Df: 0.0038, moisture absorption rate: 0.6 wt%) was prepared in the same manner as in Preparation Example 1, except that the cured thickness was approximately 12 μm using polyamic acid solution 2.

[0127] [Example 1] Polyimide varnish 1 was applied to polyimide film 2 to a thickness of 25 μm after drying, and then heated and dried at 80°C for 15 minutes. Subsequently, polyimide varnish 1 was applied to the opposite side to the previously applied surface to a thickness of 25 μm after drying, and heated and dried at 80°C for 15 minutes to obtain Bondply 1. The evaluation results of Bondply 1 are shown in Table 1.

[0128] [Example 2] Bondply 2 was prepared in the same manner as in Example 1, except that the thickness of polyimide varnish 1 after drying was set to 50 μm. The evaluation results of Bondply 2 are shown in Table 1.

[0129] [Example 3] Bondply 3 was prepared in the same manner as in Example 2, except that polyimide film 5 was used instead of polyimide film 2. The evaluation results of Bondply 3 are shown in Table 1.

[0130] [Example 4] Bondply 4 was prepared in the same manner as in Example 2, except that polyimide film 1 was used instead of polyimide film 2. The evaluation results of Bondply 4 are shown in Table 1.

[0131] [Example 5] Bondply 5 was obtained in the same manner as in Example 2, except that polyimide film 3 was used instead of polyimide film 2. The evaluation results of Bondply 5 are shown in Table 1.

[0132] Comparative Example 1 Bondply 6 was obtained by fabricating in the same manner as in Example 2, except that polyimide film 4 was used instead of polyimide film 2. The evaluation results of Bondply 6 are shown in Table 1.

[0133] [Example 6] Bondply 7 was obtained by fabricating in the same manner as in Example 4, except that polyimide varnish 2 was used instead of polyimide varnish 1. The evaluation results of Bondply 7 are shown in Table 1.

[0134] Comparative Example 2 A polyamic acid solution 7 was uniformly applied to the polyimide film 2 to a cured thickness of approximately 50 μm, and then heated and dried at 120°C to remove the solvent. The same process was repeated on the opposite side of the polyimide film 2, where the polyamic acid solution 7 was uniformly applied to a cured thickness of approximately 50 μm, and then heated and dried at 120°C to remove the solvent. Stepwise heat treatment from 120°C to 360°C was performed to complete the imidation process and obtain Bondply 8. The evaluation results of Bondply 8 are shown in Table 1.

[0135] Comparative Example 3 Bondply 9 was obtained by fabricating in the same manner as in Example 2, except that polyimide film 6 was used instead of polyimide film 2. The evaluation results of Bondply 9 are shown in Table 1.

[0136] [Example 7] Adhesive sheets (manufactured by Nikkan Industries Co., Ltd., product side: NIKAFLEX SAFY, thickness: 50 μm) were placed on both sides of polyimide film 2, and the film was hot-pressed at a temperature of 160°C and a pressure of 4 MPa for 40 minutes to obtain Bondply 10. The evaluation results of Bondply 10 are shown in Table 1.

[0137] The results above are summarized in Table 1.

[0138] [Table 1]

[0139] As shown in Table 1, the bond plies of Examples 1 to 7 achieve both low dielectric loss tangent and dimensional stability. Therefore, when applied to circuit boards such as striplines that transmit high-frequency signals in the GHz band (e.g., 1 to 50 GHz), it is expected that the transmission loss of high-frequency signals can be effectively reduced, and reliability and yield can be improved due to the excellent dimensional stability.

[0140] [Example 8] A wiring board 1 was fabricated by forming multiple linear conductor patterns (circuit conductor width / space width = 100 μm / 100 μm) on the copper foil of a single-sided copper-clad laminate (manufactured by Nippon Steel Chemical & Material Co., Ltd., product name: ESPANEX M series) using a subtractive etching method. Two of these wiring boards 1 were prepared. Bond ply 2 was placed on the circuit processing surface of wiring board 1, and then another wiring board 1 was placed on top of it with the circuit processing surface facing outwards. The boards were then heat-pressed for 40 minutes at a temperature of 160°C and a pressure of 4MPa to obtain a multilayer circuit board 1 {Laminated structure: wiring board 1 (circuit surface inward) / bond ply 2 / wiring board 1 (circuit surface outward)}.

[0141] [Example 9] A multilayer circuit board 2 {layer configuration: circuit board 1 (circuit side facing outwards) / bond ply 2 / circuit board 1 (circuit side facing outwards)} was obtained in the same manner as in Example 8, except that the two wiring boards 1 were arranged so that their circuit processing surfaces faced outwards, and a bond ply 2 was further laminated between the two wiring boards 1.

[0142] [Example 10] A wiring board 2 was fabricated by forming multiple linear conductor patterns (circuit conductor width / space width = 100 μm / 100 μm) on one side of the copper foil of a double-sided copper-clad laminate (manufactured by Nippon Steel Chemical & Material Co., Ltd., product name: ESPANEX M series) using a subtractive etching method. A multilayer circuit board 3 {laminated structure; wiring board 2 (copper foil side outward, circuit side inward) / bond ply 2 / single-sided copper-clad laminate (copper foil side outward)} was obtained in the same manner as in Example 8, except that the bond ply 2 was placed on the circuit processing surface of the wiring board 2, and then the single-sided copper-clad laminate was placed on top of it with the copper foil side facing outward.

[0143] [Example 11] Multiple linear conductor patterns (circuit conductor width / space width = 100 μm / 100 μm) were formed on the copper foil of both sides of a double-sided copper-clad laminate by subtractive etching, and a wiring board 3 was fabricated. A multilayer circuit board 4 {laminated structure; wiring board 3 / bond ply 2 / single-sided copper-clad laminate (copper foil side facing outwards)} was obtained in the same manner as in Example 10, except that wiring board 3 was used instead of wiring board 2.

[0144] [Example 12] A multilayer circuit board 5 {laminated structure; wiring board 2 (copper foil side outward, circuit side inward) / bond ply 2 / wiring board 1 (circuit side outward)} was obtained in the same manner as in Example 10, except that wiring board 1 was used instead of a single-sided copper-clad laminate and the wiring board 1 was positioned so that the circuit processing side was on the outside.

[0145] [Example 13] A multilayer circuit board 6 {laminated configuration; wiring board 3 / bond ply 2 / wiring board 1 (circuit side facing outwards)} was obtained in the same manner as in Example 12, except that wiring board 3 was used instead of wiring board 2.

[0146] [Example 14] Two single-sided copper-clad laminates, two bond plies 2, and a wiring board 1 were prepared. The laminates were stacked in the following configuration: single-sided copper-clad laminate (copper foil side facing outwards) / bond plies 2 / wiring board 1 (circuit side orientation not specified) / bond plies 2 / single-sided copper-clad laminate (copper foil side facing outwards). A multilayer circuit board 7 was obtained by hot pressing at a temperature of 160°C and a pressure of 4MPa for 40 minutes.

[0147] Although embodiments of the present invention have been described in detail above for illustrative purposes, the present invention is not limited to the above embodiments and various modifications are possible. [Explanation of Symbols]

[0148] 10...Polyimide layer, 20A...First adhesive layer, 20B...Second adhesive layer, 30A...First metal layer, 30B...Second metal layer, 40A...First insulating resin layer, 40B...Second insulating resin layer, 50...Wiring layer, 60A...First laminate, 100...Bond ply, 101...Intermediate resin layer, 200...Stripline

Claims

1. A non-thermoplastic polyimide layer comprising a resin component made of non-thermoplastic polyimide, A first adhesive layer laminated in contact with one side of the non-thermoplastic polyimide layer, A second adhesive layer is laminated in contact with the side of the non-thermoplastic polyimide layer opposite to the first adhesive layer, A bond ply equipped with, The following conditions a to c; a) The total thickness of the bond ply is within the range of 100 μm to 300 μm, and the ratio of the thickness of the non-thermoplastic polyimide layer to the total thickness of the bond ply is within the range of 0.3 to 0.9; b) After drying at 80°C for 1 hour, the moisture absorption rate measured after 24 hours of constant temperature and humidity at 23°C and 50% RH is 0.4% by weight or less; c) The storage modulus of the first adhesive layer and the second adhesive layer at 50°C is independently 1800 MPa or less, and the maximum value of the storage modulus at 180 to 260°C is independently 800 MPa or less; A bond ply characterized by satisfying the following conditions.

2. Furthermore, the following condition d; d) The dielectric loss tangent at 10 GHz, measured by a split-post dielectric resonator (SPDR) after 24 hours of conditioning under constant temperature and humidity conditions (normal state) of 23°C and 50% RH, must be 0.004 or less: The bond ply according to claim 1 that satisfies the following conditions.

3. The bond ply according to claim 1 or 2, wherein the first adhesive layer and the second adhesive layer each have a glass transition temperature (Tg) of 180°C or less.

4. The first adhesive layer and the second adhesive layer contain polyimide as a resin component, The bond ply according to any one of claims 1 to 3, wherein the polyimide contains acid anhydride residues derived from a tetracarboxylic anhydride component and diamine residues derived from a diamine component, and also contains 50 mol% or more of diamine residues derived from a dimer amine composition mainly composed of a dimer amine in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

5. The bond ply according to any one of claims 1 to 4, wherein the thermal expansion coefficient of the non-thermoplastic polyimide layer is in the range of 1 ppm / K or more and 30 ppm / K or less.

6. The bond ply according to any one of claims 1 to 5, wherein the dielectric loss tangent at 10 GHz measured by a split post dielectric resonator (SPDR) after 24 hours of conditioning under constant temperature and humidity conditions (normal state) of 23°C and 50% RH of the non-thermoplastic polyimide layer is 0.006 or less.

7. The bond ply according to any one of claims 1 to 6, characterized in that the polyimide constituting the non-thermoplastic polyimide layer contains tetracarboxylic acid residues and diamine residues, and the content of diamine residues derived from a diamine compound represented by the following general formula (A1) is 50 mol% or more relative to the total number of diamine residues. 【Chemistry 1】 [In formula (A1), the linking group Z represents a single bond or -COO-, Y independently represents a C1-C3 monovalent hydrocarbon, a C1-C3 alkoxy group, a C1-C3 perfluoroalkyl group, or an alkenyl group, which may be substituted with a halogen atom or a phenyl group, n represents an integer from 0 to 2, and p and q independently represent integers from 0 to 4.]

8. A circuit board comprising a bond ply according to any one of claims 1 to 7.

9. The first metal layer and A first insulating resin layer consisting of one or more layers laminated on one side surface of the first metal layer, A wiring layer provided in contact with the first insulating resin layer, The second metal layer, A second insulating resin layer consisting of one or more layers laminated on one side surface of the second metal layer, An intermediate resin layer is laminated between the first insulating resin layer and the second insulating resin layer, Equipped with, A stripline in which the intermediate resin layer is made of bond ply according to any one of claims 1 to 7, and the wiring layer is covered with the first adhesive layer or the second adhesive layer.

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