Double-sided metal-clad laminate and circuit board

Abstract

The present application provides a kind of double-sided metal-clad laminated board and circuit substrate, with excellent dimensional stability can also be faced with size Large-scale.A kind of double-sided metal-clad laminated board, including insulating resin layer and the metal layer of the two sides of laminated in the insulating resin layer long strip film type double-sided metal-clad laminated board, and the length of the width direction of double-sided metal-clad laminated board with length direction orthogonal is 230mm or more, when the thickness direction birefringence of at least three measurement sites is measured to the multiple measurement sites of the same length direction position and different width direction positions in the insulating resin layer is set, in the coordinate of the value of the thickness direction birefringence is set as longitudinal axis, the width direction distance from the arbitrary reference position of width direction to each measurement site is set as transverse axis, the absolute value of the slope of straight line obtained by least square method to the plotting point corresponding to each measurement site is less than 1 × 10 ‑5 / mm.

Description

TECHNICAL FIELD

[0001] The present application relates to a double-sided metal-clad laminate and a circuit board. BACKGROUND

[0002] In recent years, along with the development of miniaturization, weight reduction, and space saving of electronic devices, the demand for flexible printed wiring boards (FPCs) that are thin and light, have flexibility, and have excellent durability even when repeatedly bent is increasing. FPCs enable three-dimensional and high-density mounting even in limited spaces, and thus their use is expanding to parts such as wiring or cables, connectors, and the like for movable portions of electronic devices such as hard disk drives (HDDs), digital versatile discs (DVDs), mobile phones, smartphones, and the like.

[0003] FPCs are manufactured by etching and wiring processing a metal layer of a metal-clad laminate having a metal layer and an insulating resin layer. In a photolithography process performed on the metal-clad laminate or a process of mounting the FPC, various processes such as bonding, cutting, exposure, etching, and the like are performed. The processing accuracy in these processes becomes important in maintaining the reliability of electronic devices in which the FPCs are mounted.

[0004] However, the metal-clad laminate has a structure in which metal layers having different coefficients of thermal expansion (hereinafter sometimes referred to as "CTE") and insulating resin layers are laminated, and thus internal stress is generated between the layers due to the difference in the coefficients of thermal expansion (CTE) of the metal layers and the insulating resin layers. The internal stress is released when the metal layers are etched and wiring processing is performed, and thus the insulating resin layers expand and contract, which becomes a main cause of changes in the size of wiring patterns. In addition, in a process of manufacturing a double-sided metal-clad laminate by adhering a single-sided metal-clad laminate and a metal foil using a continuous press device, strain is generated in the plane of the double-sided metal-clad laminate and the dimensional stability is reduced due to pressure unevenness when hot press bonding is performed using press rollers or alignment deviation of the rollers arranged in a paper conveying line from the rollers to the winding.

[0005] Due to the main causes such as those described above, if changes in the size occur finally at the stage of the circuit board, it becomes a cause of connection failure between wirings or between wirings and terminals, and thus the reliability or yield of the circuit board is reduced. Therefore, in a double-sided metal-clad laminate as a circuit board material, dimensional stability is a very important characteristic.

[0006] As a technique for improving the dimensional stability of a metal-clad laminate, Patent Literature 1 proposes that, in addition to setting the thermal expansion coefficient of a polyimide insulating layer to be within a prescribed range, the product of the thickness and tensile elastic coefficient of a rolled copper foil is also set to be within a prescribed range. In addition, Patent Literature 2 proposes reducing the deviation (ΔRO) in the value of in-plane retardation (RO) in the width direction (Transverse Direction (TD) direction) from the in-plane retardation (RO). Further, Patent Literature 3 proposes a polarizing optical element and a polarization state control device that can adjust the phase difference generated between two linearly polarized lights whose polarization directions are orthogonal to each other.

[0007] [Related Art Documents]

[0008] [Patent Literature]

[0009] [Patent Literature 1] Japanese Patent Application Laid-Open (kokai) No. 2016-60138

[0010] [Patent Literature 2] Japanese Patent Application Laid-Open (kokai) No. 2017-200759

[0011] [Patent Literature 3] Japanese Patent Application Laid-Open (kokai) No. 2016-126804 SUMMARY

[0012] [Problems to be Solved by the Invention]

[0013] It is expected that the demand for FPCs in electronic devices will increase in the future, and therefore, for metal-clad laminates as the material thereof, there is a demand for larger sizes, particularly an increase in the length in the width direction, in order to be able to process and produce as many FPCs as possible. In this case, particularly in a double-sided metal-clad laminate in which a metal foil is laminated to a single-sided metal-clad laminate having a length in the width direction of 500 mm or more, there is a problem in that the dimensional change rate in the length direction of the insulating resin layer varies depending on the position in the width direction. Therefore, not only is it required to suppress the dimensional change rate in the length direction of the insulating resin layer in the double-sided metal-clad laminate to be small, but it is also required to reduce the variation range thereof as much as possible so that the dimensional change rate is substantially constant even if the position in the width direction changes.

[0014] An object of the present application is to provide a double-sided metal-clad laminate in which the variation range of the dimensional change rate in the length direction of the insulating resin layer is small regardless of the position in the width direction, and which has excellent dimensional stability and is also able to cope with the large-scale of the size.

[0015] [Technical Means for Solving the Problems]

[0016] As a result of diligent studies by the present inventors and others, it has been found that a two-sided metal-clad laminate produced by controlling the width direction tension balance after laminating a metal foil to a single-sided metal-clad laminate having a length in the width direction of 500 mm or more using a continuous press device is capable of solving the problems described above, and thus the present invention has been completed.

[0017] That is, the two-sided metal-clad laminate of the first aspect of the present invention is a long, film-shaped two-sided metal-clad laminate including an insulating resin layer and metal layers laminated on both sides of the insulating resin layer, and

[0018] The length in the width direction orthogonal to the length direction of the two-sided metal-clad laminate is 230 mm or more,

[0019] When measuring the thickness direction birefringence at at least three measurement sites provided at symmetrical positions with respect to a center line connecting the midpoints of the entire length in the width direction of the insulating resin layer for a plurality of measurement sites having the same position in the length direction and different positions in the width direction in the insulating resin layer, the absolute value of the slope of a straight line obtained by approximating the plotted points corresponding to each measurement site using the least squares method in a coordinate in which the value of the thickness direction birefringence is set as the ordinate and the distance in the width direction from an arbitrary reference position in the width direction to each measurement site is set as the abscissa is less than 1 x 10 -5 / mm.

[0020] In addition, the two-sided metal-clad laminate of the second aspect of the present invention is a long, film-shaped two-sided metal-clad laminate including an insulating resin layer and metal layers laminated on both sides of the insulating resin layer. In the two-sided metal-clad laminate of the second aspect of the present invention, the length in the width direction orthogonal to the length direction of the two-sided metal-clad laminate is 500 mm or more and 1200 mm or less. Furthermore, in the two-sided metal-clad laminate of the second aspect of the present invention, when measuring the thickness direction birefringence at at least three measurement sites provided at symmetrical positions with respect to a center line connecting the midpoints of the entire length in the width direction of the insulating resin layer for a plurality of measurement sites having the same position in the length direction and different positions in the width direction in the insulating resin layer, the absolute value of the slope of a straight line obtained by approximating the plotted points corresponding to each measurement site using the least squares method in a coordinate in which the value of the thickness direction birefringence is set as the ordinate and the distance in the width direction from an arbitrary reference position in the width direction to each measurement site is set as the abscissa is less than 1 x 10 -5 / mm.

[0021] In the two-sided metal-clad laminate of the first aspect or the second aspect of the present invention, the value of the thickness direction birefringence of all measurement sites can be 0.15 or less.

[0022] In the two-sided metal-clad laminate board of the first or second aspect of the present application, when the insulating resin layer is divided into two virtual regions with a center line joining the midpoints of the full length in the width direction as a boundary, all of the measurement sites can be set in the range from the center line to 49% of the full length in the width direction in each of the two virtual regions.

[0023] In the two-sided metal-clad laminate board of the first or second aspect of the present application, the insulating resin layer can include a plurality of polyimide layers, and the metal layer is a copper layer.

[0024] The circuit substrate of the present application is formed by processing one or both of the metal layers of the two-sided metal-clad laminate board of the first or second aspect of the present application into wiring.

[0025] [Effects of the Invention]

[0026] The two-sided metal-clad laminate board of the present application has a length in the width direction of 500 mm or more at the time of lamination, and the absolute value of the slope of the approximate straight line obtained by measuring the birefringence in the thickness direction of the insulating resin layer at different positions in the width direction is less than 1 x 10 -5 / mm. This indicates that the dimensional change in the length direction of the insulating resin layer is basically stable regardless of the position in the width direction, and has excellent dimensional stability. Therefore, when the metal layer is circuit-processed, the deviation in the wiring interval caused by the processing site of the two-sided metal-clad laminate board in the plane, particularly in the width direction, can be suppressed to a very small extent. Therefore, by using the two-sided metal-clad laminate board of the present application, the reduction in yield can be suppressed, and the reliability of the circuit substrate can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a drawing showing the external structure of the two-sided metal-clad laminate board of an embodiment of the present application.

[0028] Figure 2 is an explanatory drawing of simulated coordinates showing the relationship between the value of the birefringence in the thickness direction and the distance to the measurement site in the width direction.

[0029] Figure 3 is an explanatory drawing of the position of the measurement site on the horizontal axis of the coordinates shown in Figure 2

[0030] Figure 4 is a drawing for explaining the evaluation system for the retardation used in the examples and comparative examples.

[0031] Figure 5 is a schematic diagram for explaining the measurement method for the retardation used in the examples and comparative examples.

[0032] Figure 6 ​is a view for explaining a method for measuring a dimensional change rate after etching.

[0033] Figure 7 is a graph showing the deviation in the width direction of the dimensional change rate after etching of the two-sided metal-clad laminate obtained in Example 1 and Comparative Example 1.

[0034] [Explanation of symbols]

[0035] 2: Polyimide film

[0036] 2a: Laminated surface

[0037] 2b: Casting surface

[0038] 10: Measurement site

[0039] 10a: Center of measurement site

[0040] 20: Test sample

[0041] 21: Light source

[0042] 22: Light receiving portion

[0043] 100: Two-sided metal-clad laminate

[0044] 100A: Fragment

[0045] A, B: Virtual regions

[0046] A, B, C, D, E, F: Measurement positions

[0047] d: Thickness / film thickness

[0048] θ1: Angle of incidence

[0049] θ2: Angle of refraction

[0050] Lo: Center line

[0051] L1, L2, L3: Light

[0052] N1 to N10, S1 to S10: Hole symbols

[0053] TD, MD: Directions DETAILED DESCRIPTION

[0054] [Two-sided metal-clad laminate]

[0055] While the embodiments of the present application are described with appropriate reference to the accompanying drawings, it is to be understood that the application is not limited to the embodiments. Figure 1 The embodiments of the present application will be described with appropriate reference to the accompanying drawings. Figure 1An appearance structure of a double-sided metal-clad laminate 100 representing one embodiment of the present application. The double-sided metal-clad laminate 100 is in the form of a long film as a whole. Although not shown, the double-sided metal-clad laminate 100 has an insulating resin layer and metal layers laminated on both sides of the insulating resin layer. In the following description, the length direction of the double-sided metal-clad laminate 100 in the form of a long film is sometimes referred to as the machine direction (MD) direction, the width direction orthogonal to the MD direction is referred to as the TD direction, and the axial direction orthogonal to the plane (xy plane) formed by the MD direction and the TD direction is referred to as the thickness direction (z direction). The same applies to the insulating resin layer and the metal layers (metal foils) in the double-sided metal-clad laminate 100, the fragment 100A described later, and the test piece 20.

[0056] The two-sided metal-clad laminate 100 can have a length in the width direction (TD direction) orthogonal to the length direction of 230 mm or more, but in a preferred aspect thereof, the width (length in the TD direction) can be in a range of 500 mm or more and 1200 mm or less. By having a length in the TD direction of 500 mm or more, the production efficiency when performing circuit processing on the two-sided metal-clad laminate 100 can be improved, but generally, the larger the width at the time of lamination, the more difficult it is to control the dimensional stability and the tendency toward in-plane isotropy after lamination. That is, the larger the length in the TD direction at the time of lamination, the more likely it is that the value of the birefringence in the thickness direction Δn(xy-z) (hereinafter sometimes referred to as "Δn(xy-z)") measured in multiple portions in the same direction will deviate, and in the two-sided metal-clad laminate 100 of the present application, this aspect is improved, and the variation in Δn(xy-z) is small. Here, the "birefringence in the thickness direction Δn(xy-z)" refers to the difference between the in-plane direction (xy plane) refractive index Nxy and the thickness (cross-sectional) direction (z direction) refractive index Nz in the insulating resin layer. Since the tendency for the molecules to align in the in-plane direction becomes stronger as the molecular orientation progresses, Δn(xy-z) becomes larger, and in the case where no orientation has been performed, Δn(xy-z) becomes smaller. Therefore, the degree of molecular orientation can be evaluated using Δn(xy-z). Furthermore, the degree of molecular orientation can have an effect on the dimensional change in the MD direction after etching. That is, from Δn(xy-z), it is possible to grasp to what extent the dimensional change in the MD direction after etching will occur. As will be described later, in a manufacturing method in which a single-sided metal-clad laminate and a metal foil are heat-pressed using a press roll in a roll-to-roll manner, there is a tendency for Δn(xy-z) to deviate in the TD direction, and this tendency becomes significant in the case where the length in the TD direction is 500 mm or more. Accordingly, the effect of the present application is particularly large in a two-sided metal-clad laminate having a width of 500 mm or more at the time of lamination. Furthermore, if the width exceeds 1200 mm, the dimensional stability in the plane or the variation in the thickness becomes large, and for example, there is a tendency for defects to occur when processing into an FPC or the like, and the yield deteriorates.

[0057] <Insulating Resin Layer>

[0058] The insulating resin layer is preferably a non-thermoplastic polyimide layer and thermoplastic polyimide layers laminated on both sides of the non-thermoplastic polyimide layer. The insulating resin layer is preferably formed by a casting method in which a solution of thermoplastic polyimide or non-thermoplastic polyimide, or a solution of these precursors is sequentially applied. For example, in the case where the insulating resin layer is formed by a casting method, a three-layer structure in which a thermoplastic polyimide layer, a non-thermoplastic polyimide layer, and a thermoplastic polyimide layer are sequentially laminated from the casting surface side of the insulating resin layer is preferred. Here, the "casting surface" of the insulating resin layer refers to the side of the metal layer to which the polyimide or the solution of the precursor thereof is applied. Further, the side of the insulating resin layer opposite the casting surface is sometimes referred to as the "lamination surface".

[0059] In the present embodiment, as the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer and the thermoplastic polyimide constituting the thermoplastic polyimide layer, a general non-thermoplastic polyimide and a thermoplastic polyimide can be used without particular limitation as a circuit board material. Here, the "non-thermoplastic polyimide" is a polyimide that does not soften even when heated and does not exhibit tackiness, and in the present specification, refers to a polyimide other than a thermoplastic polyimide, and preferably refers to a polyimide having a storage elastic modulus of 1.0 x 10 9 Pa or more and a storage elastic modulus of 3.0 x 10 8 Pa or more at 280°C. Further, the "thermoplastic polyimide" is a polyimide in which the glass transition temperature (Tg) can be clearly confirmed, and in the present specification, preferably refers to a polyimide having a storage elastic modulus of 1.0 x 10 9 Pa or more at 30°C and a storage elastic modulus of less than 3.0 x 10 8 Pa at 280°C.

[0060] Further, in the insulating resin layer, the thickness ratio of the thickness (A) of the non-thermoplastic polyimide layer to the thickness (B) of the thermoplastic polyimide layer ((A) / (B)) is preferably in the range of 1 to 20, more preferably in the range of 2 to 12. Further, in the case where the number of layers of the non-thermoplastic polyimide layer and / or the thermoplastic polyimide layer is plural, the thickness (A) or the thickness (B) refers to the total thickness. If the value of the ratio is less than 1, the non-thermoplastic polyimide layer becomes thin with respect to the entire insulating resin layer, and thus the variation in the in-plane birefringence Δn(x-y) (hereinafter sometimes referred to as "Δn(x-y)") easily becomes large, and if the ratio exceeds 20, the thermoplastic polyimide layer becomes thin, and thus the adhesion reliability of the insulating resin layer to the metal layer easily decreases. Here, Δn(x-y) is the difference between the two refractive indexes Nx and Ny in the xy plane in the insulating resin layer. Further, the refractive index Nxy in the in-plane direction (xy plane) is the average of the refractive index Nx in the x direction and the refractive index Ny in the y direction. The control of Δn(x-y) is related to the resin structure of each polyimide layer constituting the insulating resin layer and the thickness thereof. The greater the thickness of the thermoplastic polyimide layer having a resin structure imparted with adhesion, i.e., high thermal expansion or softening, the greater the influence on the value of Δn(x-y) of the insulating resin layer. Therefore, it is preferable to increase the ratio of the thickness of the non-thermoplastic polyimide layer and decrease the ratio of the thickness of the thermoplastic polyimide layer, thereby decreasing the value of Δn(x-y) of the insulating resin layer and the variation thereof. As described later, in the present embodiment, even in the case where the ratio of the thickness of the thermoplastic polyimide layer is decreased, by designing the thermoplastic polyimide layer to contain a prescribed amount of the diamine residue selected from the group consisting of the general formula (2) and the general formula (3), the adhesion of the metal layer to the insulating resin layer can be ensured.

[0061] From the viewpoint of more greatly exhibiting the improvement effect of the dimensional accuracy of the insulating resin layer, the double-sided metal-clad laminate sheet 100 of the present embodiment is preferably a long strip having a width (length in the TD direction) of 500 mm or more and a length of 20 m or more. Further, as described later, after the double-sided metal-clad laminate sheet 100 of the present embodiment is continuously manufactured, it is sometimes cut at a certain fixed value in the length direction (MD direction) and the TD direction of the long double-sided metal-clad laminate sheet 100 and used, and such slit-processed laminate sheet is also included in the double-sided metal-clad laminate sheet 100 of the present embodiment.

[0062] (non-thermoplastic polyimide)

[0063] In the present embodiment, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer contains tetracarboxylic acid residues and diamine residues, and it is preferable that both of them contain aromatic groups, and it is more preferable that all of the tetracarboxylic acid residues and the diamine residues contain only aromatic groups. The tetracarboxylic acid residues and the diamine residues contained in the non-thermoplastic polyimide each contain an aromatic group, whereby an ordered structure of the non-thermoplastic polyimide is easily formed, and it is possible to suppress the variation in Δn(x-y) of the insulating resin layer in a high-temperature environment while reducing the variation in Δn(x-y) of the insulating resin layer in a high-temperature environment, and it is possible to suppress the deviation in Δn(x-y).

[0064] Further, in the present application, the "tetracarboxylic acid residue" means a tetravalent group derived from a tetracarboxylic dianhydride, and the "diamine residue" means a divalent group derived from a diamine compound. In addition, in the "diamine compound", the hydrogen atoms in the two terminal amino groups can be substituted, and for example, can be -NR3R4 (here, R3, R4 independently indicate an arbitrary substituent such as an alkyl group).

[0065] There is no particular limitation on the tetracarboxylic acid residues contained in the non-thermoplastic polyimide, and for example, it is possible to preferably cite a tetracarboxylic acid residue derived from pyromellitic dianhydride (PMDA) (hereinafter also referred to as a PMDA residue), and a tetracarboxylic acid residue derived from 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) (hereinafter also referred to as a BPDA residue). These tetracarboxylic acid residues easily form an ordered structure, and it is possible to reduce the variation in Δn(x-y) in a high-temperature environment. In addition, the PMDA residue is a residue that plays a role in controlling the coefficient of thermal expansion and controlling the glass transition temperature. Furthermore, the BPDA residue has no polar group among the tetracarboxylic acid residues, and has a large molecular weight, and thus it is also possible to expect an effect of reducing the imide group concentration of the non-thermoplastic polyimide and suppressing the moisture absorption of the insulating resin layer. From this viewpoint, the total amount of the PMDA residue and / or the BPDA residue can be preferably 50 mol or more, more preferably in the range of 50 mol to 100 mol, and most preferably in the range of 70 mol to 100 mol, with respect to 100 mol of all of the tetracarboxylic acid residues contained in the non-thermoplastic polyimide.

[0066] Other tetracarboxylic acid residues contained in non-thermoplastic polyimides include, for example, tetracarboxylic acid residues derived from the following aromatic tetracarboxylic dianhydrides: 2,3',3,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 4,4'-oxophthalic anhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride or 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',3,4'-diphenyl ether tetracarboxylic dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3'- 4,4”-p-terphenyltetracarboxylic acid dianhydride, 2,3,3”,4”-p-terphenyltetracarboxylic acid dianhydride or 2,2”,3,3”-p-terphenyltetracarboxylic acid dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-propane dianhydride or 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride or bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)sulfone dianhydride or bis(3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride or 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-phenanthrene- Tetracarboxylic dianhydride, 1,2,6,7-phenanthrene-tetracarboxylic dianhydride or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracene-tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalene-tetracarboxylic dianhydride, 1,4,5,8-naphthalene-tetracarboxylic dianhydride, 2,3,6,7-naphthalene-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-Tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride or 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,3,8,9-perylene-tetracarboxylic dianhydride, 3,4,9,10-perylene-tetracarboxylic dianhydride, 4,5,10,11-perylene-tetracarboxylic dianhydride or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, etc.

[0067] The diamine residues contained in the non-thermoplastic polyimide are preferably diamine residues derived from diamine compounds represented by the following general formula (1) (hereinafter sometimes referred to as "diamine residue (1)").

[0068] [Chemistry 1]

[0069]

[0070] In General Formula (1), the linking group Z represents a single bond or -COO-, Y independently represents a monovalent hydrocarbon group having a carbon number of 1 to 3 which can be substituted with a halogen or a phenyl group, or an alkoxy group having a carbon number of 1 to 3, or a perfluoroalkyl group or an alkenyl group having a carbon number of 1 to 3, n represents an integer of 0 to 2, and p and q independently represent an integer of 0 to 4. Here, the term "independently" means that the plurality of substituents Y, the integers p, q in the formula (1) can be the same or different.

[0071] The diamine residue (1) easily forms an ordered structure, improves dimensional stability, and particularly effectively suppresses the change in Δn(x-y) under a high temperature environment. From this viewpoint, the diamine residue (1) can be contained in a range of 20 mol or more, preferably 70 mol to 95 mol, and more preferably 80 mol to 90 mol, relative to 100 mol of the total diamine residues contained in the non-thermoplastic polyimide.

[0072] As a preferable specific example of the diamine residue (1), a diamine residue derived from a diamine compound such as p-phenylenediamine (p-PDA), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), 2,2'-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), and the like can be exemplified. Among these, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) is particularly preferable because it easily forms an ordered structure and can reduce the change in Δn(x-y) under a high temperature environment.

[0073] In addition, in order to reduce the elastic modulus of the insulating resin layer and improve the elongation and the bending resistance and the like, it is preferable that the non-thermoplastic polyimide contain at least one diamine residue selected from the group consisting of diamine residues represented by General Formula (2) and General Formula (3) below.

[0074] [Chem. 2]

[0075]

[0076] In the formula (2) and the formula (3), R5, R6, R7, and R8 each independently represent a halogen atom, or a carbon number 1 to 4 alkyl group or alkoxy group or alkenyl group which can be substituted with a halogen atom, X independently represents a divalent group selected from -0-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -CO-, -COO-, -SO2-, -NH-, or -NHCO-, X1 and X2 each independently represent a divalent group selected from a single bond, -0-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -CO-, -COO-, -SO2-, -NH-, or -NHCO-, m, n, o, and p independently represent an integer of 0 to 4, except for the case where both X1 and X2 are a single bond.

[0077] Further, the "independently" means that the plurality of linking groups X, the linking groups X1 and X2, the plurality of substituents R5, R6, R7, R8, and the integers m, n, o, p can be the same or different in one or both of the formula (2) and the formula (3).

[0078] The diamine residue represented by the general formula (2) and the general formula (3) has a site of flexibility, and thus the insulating resin layer can be imparted with flexibility. Here, the benzene ring of the diamine residue represented by the general formula (3) is four, and thus in order to suppress an increase in the coefficient of thermal expansion (CTE), the terminal group bonded to the benzene ring is preferably set to the para position. In addition, from the viewpoint of imparting flexibility to the insulating resin layer while suppressing an increase in the coefficient of thermal expansion (CTE), the diamine residue represented by the general formula (2) and the general formula (3) can be contained in a range of preferably 5 mol% to 30 mol%, more preferably 10 mol% to 20 mol%, with respect to 100 mol% of all diamine residues contained in the non-thermoplastic polyimide. If the diamine residue represented by the general formula (2) and the general formula (3) is less than 5 mol%, the elastic modulus of the insulating resin layer increases, the elongation decreases, and sometimes a decrease in the bending resistance and the like occurs, and if it exceeds 30 mol%, the molecular orientation decreases, and sometimes it is difficult to achieve low CTE.

[0079] The diamine residue represented by General Formula (2) is preferably one in which one or more of m, n, and o is 0, and as preferred examples of the groups R5, R6, and R7, mention can be made of an alkyl group having 1 to 4 carbon atoms which can be substituted with a halogen atom, or an alkoxy group having 1 to 3 carbon atoms, or an alkenyl group having 2 to 3 carbon atoms. Also, in General Formula (2), as preferred examples of the linking group X, mention can be made of -0-, -S-, -CH2-, -CH(CH3)-, -SO2-, or -CO-. As preferred specific examples of the diamine residue represented by General Formula (2), mention can be made of diamine residues derived from the following diamine compounds: 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), bis(4-aminophenoxy)-2,5-di-tert-butylbenzene (DTBAB), 4,4-bis(4-aminophenoxy)benzophenone (BAPK), 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, and the like.

[0080] The diamine residue represented by General Formula (3) is preferably one in which one or more of m, n, o, and p is 0, and as preferred examples of the groups R5, R6, R7, and R8, mention can be made of an alkyl group having 1 to 4 carbon atoms which can be substituted with a halogen atom, or an alkoxy group having 1 to 3 carbon atoms, or an alkenyl group having 2 to 3 carbon atoms. Also, in General Formula (3), as preferred examples of the linking groups X1and X2, mention can be made of a single bond, -0-, -S-, -CH2-, -CH(CH3)-, -SO2-, or -CO-. Among these, the case in which both of the linking groups X1and X2are single bonds is excluded from the viewpoint of imparting a bending site. As preferred specific examples of the diamine residue represented by General Formula (3), mention can be made of diamine residues derived from the following diamine compounds: 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2'-bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone, and the like.

[0081] Among the diamine residues represented by General Formula (2), a diamine residue derived from 1,3-bis(4-aminophenoxy)benzene (TPE-R) (sometimes described as a "TPE-R residue") is particularly preferable, and among the diamine residues represented by General Formula (3), a diamine residue derived from 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) (sometimes described as a "BAPP residue") is particularly preferable. The TPE-R residue and the BAPP residue have a site of flexibility, and thus can reduce the modulus of elasticity of the insulating resin layer and impart softness. In addition, the BAPP residue has a large molecular weight, and thus can also be expected to reduce the imide group concentration of the non-thermoplastic polyimide and suppress the moisture absorption of the insulating resin layer.

[0082] As other diamine residues contained in the non-thermoplastic polyimide, for example, diamine residues derived from the following aromatic diamine compounds can be listed: m-phenylenediamine (m-PDA), 4,4'-diamino diphenyl ether (4,4'-DAPE), 3,3'-diamino diphenyl ether, 3,4'-diamino diphenyl ether, 4,4'-diamino diphenyl methane, 3,3'-diamino diphenyl methane, 3,4'-diamino diphenyl methane, 4,4'-diamino diphenyl propane, 3,3'-diamino diphenyl propane, 3,4'-diamino diphenyl propane, 4,4'-diamino diphenyl sulfide, 3,3'-diamino diphenyl sulfide, 3,4'-diamino diphenyl sulfide, 4,4'-diamino diphenyl sulfone, 3,3'-diamino diphenyl sulfone, 4,4'-diamino benzophenone, 3,4'-diamino benzophenone, 3,3'-diamino benzophenone, 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'-diamino biphenyl, 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis-2,6-dimethylaniline, 4,4'-methylene-2,6-diethyl-aniline, 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-xylylene-2,5-diamine, p-xylylene-2,5-diamine, m-phenylenediamine, p-phenylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, and the like.

[0083] In the non-thermoplastic polyimide, by selecting the kinds of the tetracarboxylic acid residue and the diamine residue, or the respective molar ratios when two or more kinds of tetracarboxylic acid residues or diamine residues are used, the coefficient of thermal expansion, the storage elastic modulus, the tensile elastic modulus, and the like can be controlled. In addition, in the non-thermoplastic polyimide, in the case where a plurality of polyimide structural units are present, the plurality of polyimide structural units can be present in a block form or randomly, but from the viewpoint of suppressing the deviation of Δn(x-y), it is preferable that the plurality of polyimide structural units be present randomly.

[0084] The imide group concentration of the non-thermoplastic polyimide is preferably 35% by mass or less. Here, the "imide group concentration" refers to a value obtained by dividing the molecular weight of the imide group portion (-(CO)2-N-) in the polyimide by the molecular weight of the entire structure of the polyimide. If the imide group concentration exceeds 35% by mass, the molecular weight of the resin itself becomes small, and at the same time, the low moisture absorption property is also deteriorated due to an increase in the polar group. By selecting the combination of the acid anhydride and the diamine compound, the orientation property of the molecule in the non-thermoplastic polyimide is controlled, thereby suppressing an increase in the CTE accompanying a decrease in the imide group concentration, and thus the low moisture absorption property is ensured.

[0085] (Thermoplastic Polyimide)

[0086] In the present embodiment, the thermoplastic polyimide constituting the thermoplastic polyimide layer contains a tetracarboxylic acid residue and a diamine residue, and these preferably each contain an aromatic group, and more preferably the tetracarboxylic acid residue and the diamine residue each contain only an aromatic group. By containing a tetracarboxylic acid residue and a diamine residue each containing an aromatic group in the thermoplastic polyimide, the amount of change in Δn(x-y) of the insulating resin layer in a high-temperature environment can be suppressed.

[0087] There is no particular limitation on the tetracarboxylic acid residue contained in the thermoplastic polyimide, and for example, a tetracarboxylic acid residue derived from pyromellitic dianhydride (PMDA) (hereinafter also referred to as a PMDA residue), a tetracarboxylic acid residue derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) (hereinafter also referred to as a BPDA residue) can be preferably exemplified. These tetracarboxylic acid residues easily form an ordered structure, and the amount of change in Δn(x-y) in a high-temperature environment can be reduced. In addition, the PMDA residue is a residue that plays a role in controlling the coefficient of thermal expansion and controlling the glass transition temperature. Furthermore, the BPDA residue has no polar group among the tetracarboxylic acid residues, and has a large molecular weight, and thus an effect of reducing the imide group concentration of the thermoplastic polyimide and suppressing the moisture absorption of the insulating resin layer can also be expected. From this viewpoint, the total amount of the PMDA residue and / or the BPDA residue can be preferably 50 mol or more, more preferably in the range of 50 mol to 100 mol, and most preferably in the range of 70 mol to 100 mol, with respect to 100 mol of all the tetracarboxylic acid residues contained in the thermoplastic polyimide.

[0088] As the other tetracarboxylic acid residue contained in the thermoplastic polyimide, there can be mentioned a tetracarboxylic acid residue derived from the same aromatic tetracarboxylic acid dianhydride as exemplified in the non-thermoplastic polyimide.

[0089] In the present embodiment, as the diamine residue contained in the thermoplastic polyimide, at least one diamine residue selected from the general formula (2) and the general formula (3) is preferable. The diamine residue selected from the general formula (2) and the general formula (3) is preferably 50 mol% or more, more preferably in the range of 50 mol% to 100 mol%, and most preferably in the range of 70 mol% to 100 mol%, based on 100 mol% of the total diamine residue. By containing 50 mol% or more of the diamine residue selected from the general formula (2) and the general formula (3) based on 100 mol% of the total diamine residue, the thermoplastic polyimide layer can be imparted with softness and adhesion, and can function as an adhesion layer to the metal layer. Further, among the diamine residues represented by the general formula (2), the TPE-R residue is particularly preferable, and among the diamine residues represented by the general formula (3), the BAPP residue is particularly preferable. The TPE-R residue and the BAPP residue have a bending site, and thus can reduce the modulus of elasticity of the insulating resin layer and impart softness. Further, the BAPP residue has a large molecular weight, and thus can also be expected to reduce the imide group concentration of the thermoplastic polyimide and suppress the moisture absorption of the insulating resin layer.

[0090] Further, as described above, in the case where the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer contains a diamine residue selected from the general formula (2) and the general formula (3), the thermoplastic polyimide constituting the thermoplastic polyimide layer can contain a similar structure, and preferably the same diamine residue selected from the general formula (2) and the general formula (3) as the diamine residue. In this case, the content ratio of the diamine residue is different between the thermoplastic polyimide and the non-thermoplastic polyimide, but by containing a similar or the same diamine residue, particularly in the case of forming a polyimide film by a casting method, the orientation control of the thermoplastic polyimide layer and the non-thermoplastic polyimide layer becomes easy, and the dimensional accuracy can be easily managed. From this viewpoint, in the present embodiment, it is preferable that the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer and the thermoplastic polyimide constituting the thermoplastic polyimide layer both contain at least one diamine residue selected from the general formula (2) and the general formula (3), and most preferably contain the TPE-R residue and / or the BAPP residue.

[0091] In the present embodiment, as the diamine residue other than the general formula (2) and the general formula (3) contained in the thermoplastic polyimide, for example, a diamine residue derived from the following diamine compound can be exemplified: 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), 2,2'-di-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,3-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, (3,3'-diamino)diphenylamine, 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]aniline, 3-[3-(4-aminophenoxy)phenoxy]aniline, 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bis(oxy)]dianiline, 4,4'-[4-methyl-(1,3-phenylene)bis(oxy)]dianiline, 4,4'-[5-methyl-(1,3-phenylene)bis(oxy)]dianiline, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, bis[4,4'-(3-aminophenoxy)]benzanilide, 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]dianiline, bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK), bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl, and the like.

[0092] In the thermoplastic polyimide, by selecting the kinds of the tetracarboxylic acid residue and the diamine residue, or the respective molar ratios when two or more kinds of tetracarboxylic acid residues or diamine residues are used, the coefficient of thermal expansion, the tensile elastic coefficient, the glass transition temperature, and the like can be controlled. In addition, in the thermoplastic polyimide, in the case where a plurality of polyimide structural units are present, they can exist in a block form or randomly, but random existence is preferred.

[0093] The thermoplastic polyimide constituting the thermoplastic polyimide layer can improve adhesion to the metal layer. The glass transition temperature of such a thermoplastic polyimide is in the range of 200°C or higher and 350°C or lower, and preferably in the range of 200°C or higher and 320°C or lower.

[0094] The imide group concentration of the thermoplastic polyimide is preferably 35% by weight or less. Here, the "imide group concentration" refers to the value obtained by dividing the molecular weight of the imide group portion (-(CO)2-N-) in the polyimide by the molecular weight of the entire structure of the polyimide. If the imide group concentration exceeds 35% by weight, the molecular weight of the resin itself becomes small, and at the same time, the low moisture absorption property is also deteriorated due to the increase in the polar group. By selecting the combination of the acid anhydride and the diamine compound to control the orientation property of the molecules in the thermoplastic polyimide, the increase in the CTE accompanying the decrease in the imide group concentration is suppressed, and thus the low moisture absorption property is ensured.

[0095] (Synthesis of non-thermoplastic polyimide and thermoplastic polyimide)

[0096] Generally, the polyimide can be produced by reacting a tetracarboxylic dianhydride and a diamine compound in a solvent to generate a polyamic acid, and then heating to close the ring. For example, the tetracarboxylic dianhydride and the diamine compound are dissolved in an organic solvent in approximately equimolar amounts, and the polymerization reaction is performed by stirring at a temperature in the range of 0°C to 100°C for 30 minutes to 24 hours, whereby a polyamic acid, which is a precursor of the polyimide, is obtained. At the time of the reaction, the reaction components are dissolved in such a manner that the resulting precursor is in the range of 5% to 30% by weight, and preferably in the range of 10% to 20% by weight, in the organic solvent. As the organic solvent used in the polymerization reaction, for example, N,N-dimethylformamide (DMF), N,N-dimethyl acetamide (DMAc), N,N-diethyl acetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, cresol, and the like can be exemplified. Two or more of these solvents can be used in combination, and further, an aromatic hydrocarbon such as xylene or toluene can be used in combination. In addition, the amount of the organic solvent used is not particularly limited, but it is preferable to use an amount adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5% to 30% by weight.

[0097] The polyamic acid synthesized is generally advantageously used as a reaction solvent solution, but can be concentrated, diluted, or replaced with another organic solvent as needed. In addition, the polyamic acid is generally excellent in solvent solubility, and thus can be advantageously used. The viscosity of the solution of the polyamic acid is preferably in the range of 500 cps to 100,000 cps. If the range is deviated, the film is likely to have thickness unevenness, streaks, or the like in the coating operation using a coater or the like. The method of imidizing the polyamic acid is not particularly limited, and for example, heat treatment at a temperature in the range of 80°C to 400°C for 1 hour to 24 hours can be suitably employed.

[0098] The weight average molecular weight of the polyimide is, for example, 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, there is a tendency that the strength of the insulating resin layer is reduced and the insulating resin layer is easily brittle. On the other hand, if the weight average molecular weight exceeds 400,000, there is a tendency that the viscosity is excessively increased and thickness unevenness, streaks, or the like are easily generated in the coating operation.

[0099] The entire insulation resin layer preferably has a CTE of 1 x 10 -6 / K or more and 30 x 10 -6 / K or less. If the CTE is less than 1 x 10 -6 / K or more than 30 x 10 -6 / K, the double-sided metal-clad laminate 100 is likely to warp in the TD direction, or the dimensional stability is likely to be impaired. The CTE of the non-thermoplastic polyimide layer can preferably be in the range of 1 x 10 -6 / K to 30 x 10 -6 / K. The CTE of the thermoplastic polyimide layer can preferably be in the range of more than 30 x 10 -6 / K and 80 x 10 -6 / K or less. The polyimide layer can be made to have a desired coefficient of thermal expansion by appropriately changing the combination, thickness, drying, and hardening conditions of the raw materials used.

[0100] The thickness of the insulation resin layer can be set to a thickness within a prescribed range according to the thickness or rigidity of the metal layer, and the like, and is preferably in the range of 6 μm to 50 μm, and more preferably in the range of 9 μm to 38 μm. If the thickness of the insulation resin layer is less than the lower limit value, there are cases in which it is not possible to ensure electrical insulation, or it becomes difficult to handle in the manufacturing process due to a decrease in handling properties, or the like. On the other hand, if the thickness of the insulation resin layer exceeds the upper limit value, there are cases in which, for example, the resistance to bending when bending the FPC decreases.

[0101] In the case where the width (length in the TD direction) of the insulation resin layer is in the range of 500 mm or more and 1200 mm or less, the absolute value of the slope of the straight line obtained by approximating the plotted points corresponding to each measurement site using the least squares method in a coordinate in which the value of Δn (xy-z) is set to the ordinate and the distance in the TD direction from an arbitrary reference position in the TD direction to each measurement site is set to the abscissa is less than 1 x 10 -5 / mm. This point will be described below with reference to Figure 2 to this point.

[0102] Figure 2 A coordinate when measuring Δn (xy-z) of the insulation resin layer at a plurality of measurement sites set at different positions in the TD direction is simulated for the double-sided metal-clad laminate 100 of the present embodiment and comparative double-sided metal-clad laminates having a width (length in the TD direction) in the range of 500 mm or more and 1200 mm or less. In the simulation, the absolute value of the slope of the straight line obtained by approximating the plotted points corresponding to each measurement site using the least squares method in a coordinate in which the value of Δn (xy-z) is set to the ordinate and the distance in the TD direction from an arbitrary reference position in the TD direction to each measurement site is set to the abscissa is less than 1 x 10 Figure 2In the diagram, the vertical axis represents the value of Δn(xy-z), and the horizontal axis represents the measurement position in the TD direction, with the end of one side of the double-sided metal-clad laminate 100 as the reference position. Here, the measurement positions at points A, B, C, D, E, and F are shown. Furthermore, the horizontal axis only needs to represent the relative distance in the TD direction from any reference position to each measurement position. Therefore, the "reference position" can be any position in the TD direction of the insulating resin layer, such as one end, the opposite end, or the midpoint in the TD direction. In addition, the measurement positions are not limited to a total of 6 points; for example, 6 to 10 points are preferred.

[0103] Figure 2 The upper straight line is obtained by approximating the set of plotted points corresponding to the circles at each measurement position of the double-sided metal-clad laminate 100 of this embodiment using the least squares method. The lower straight line is obtained by approximating the set of plotted points corresponding to the four directions at each measurement position of the double-sided metal-clad laminate of the comparison object using the least squares method. Both the upper and lower straight lines can be represented by the formula y = ax + b, where a is the slope of the line and b is any value of Δn(xy - z). Furthermore, Figure 2 The results are not actual measurements, but rather simulated graphs used for illustration. Therefore, the value of Δn(xy-z) or the slope of the line are not strictly accurate.

[0104] exist Figure 2 In the middle, the absolute value of the slope of the upper straight line, |a|, is less than 1 × 10. -5 / mm. Thus, by ensuring the slope of the approximate straight line obtained from the values ​​of Δn(xy-z) at multiple measurement locations in the TD direction is within a specified range, deviations in the dimensional change rate in the MD direction can be suppressed in the TD direction, thereby improving the dimensional stability after etching. That is, the variation in the value of Δn(xy-z) in the TD direction of the two metal-clad laminates 100 corresponding to the upper straight line is very small, indicating that the dimensional change in the MD direction after etching is approximately constant regardless of the position in the TD direction, and the magnitude of the dimensional change is extremely small.

[0105] On the other hand, Figure 2 In the middle, the absolute value of the slope |a| of the lower straight line obtained by approximating the four square plotted points using the least squares method is 1×10. -5 / mm or more. Therefore, the deviation of Δn(xy-z) values ​​at multiple measurement locations in the TD direction of the two-sided metal-coated laminate of the comparison object is large, and the dimensional changes in the MD direction after etching vary greatly depending on the position in the TD direction.

[0106] Both the double-sided metal-clad laminate 100 and the comparative double-sided metal-clad laminate are manufactured by casting. Figure 2In the comparison, regardless of the measurement position from A to F, the value of Δn(xy-z) for the square plotted points is smaller than that for the circular plotted points. Therefore, the dimensional stability of the two-sided metal-clad laminates after etching in the MD direction is considered to be excellent overall. However, as can be understood from the slope of two approximate straight lines, the deviation of Δn(xy-z) in the TD direction is larger for the square plotted points compared to the circular plotted points. Therefore, the wiring width during circuit fabrication is more likely to vary depending on the position in the TD direction. Thus, if the wiring width of the manufactured FPC differs due to the different in-plane processing positions of the two-sided metal-clad laminates, the homogeneity of quality among multiple FPCs is lacking, which becomes a problem in terms of reliability. In contrast, in the case of the circle plotting point group corresponding to the double-sided metallized laminate 100 of this embodiment, the value of Δn(xy-z) is approximately constant regardless of the position in the TD direction, with very small deviation. Therefore, even if dimensional changes occur in the MD direction after etching, countermeasures such as anticipating the dimensional changes and setting margins during circuit design can be implemented. Therefore, compared to the double-sided metallized laminate of the comparison object, the double-sided metallized laminate 100 has the advantage of easily achieving quality stabilization (especially wiring width uniformity) among the processed multiple FPCs.

[0107] Furthermore, regarding the insulating resin layer, when measuring Δn(xy-z) at multiple measurement points set at the same location in the MD direction and different locations in the TD direction, it is preferable that the value of Δn(xy-z) at all measurement points is 0.15 or less. A low value of Δn(xy-z) below 0.15 at all measurement points indicates small dimensional changes in the MD direction after etching of the insulating resin layer, resulting in high dimensional stability. This excellent dimensional stability is difficult to achieve in double-sided metal-coated laminates using polyimide films manufactured by the tenter frame method. Moreover, in Figure 2 In the example, four sets of plotted points are listed as comparison objects. However, since the double-sided metal-coated laminate of the comparison objects is manufactured by casting, the dimensional accuracy of the circuit is exceptionally superior compared to the double-sided metal-coated laminate using polyimide film manufactured by the stretching method.

[0108] As above, for the two-sided metal-clad laminate sheet 100 of the present embodiment, although the width (length in the TD direction) is in the range of 500 mm or more and 1200 mm or less, all of the measurement sites Δn(xy-z) showed low values of 0.15 or less, and thus not only the dimensional stability in the MD direction after etching was very high, but also the variation in Δn(xy-z) in the TD direction was extremely suppressed, and thus the variation in the dimensions in the MD direction after etching was extremely small in the TD direction. Therefore, the stabilization of the quality among the plurality of FPCs processed from the two-sided metal-clad laminate sheet 100 could be achieved, and thus the reliability of the FPCs could be improved.

[0109] In Figure 3 the graph, A, B, C, D, E, and F, which are six measurement positions, are shown at equal intervals on the horizontal axis. The six measurement positions refer to the positions of the measurement sites in the TD direction of the two-sided metal-clad laminate sheet 100. Specifically, as shown in Figure 2 , six rectangular regions are set as measurement sites 10 by making the positions in the MD direction coincide with each other from a piece 100A obtained by cutting the two-sided metal-clad laminate sheet 100 in the MD direction at an arbitrary length. The positions of the centers 10a of the respective measurement sites 10 (samples 20) in the rectangular shape correspond to the "measurement positions" of the horizontal axis of Figure 4 . The respective measurement sites 10 in the rectangular shape are cut from the evaluation film from which the metal layer is removed from the piece 100A by etching, and the obtained ones are used as test pieces for measuring Δn(xy-z) (samples 20 described later; refer to Figure 3 ). Further, in Figure 3 , the dimensions of the respective parts are exaggeratedly depicted for illustration.

[0110] In addition, in Figure 3 , if the six measurement sites 10 are biased in the TD direction, it is difficult to correctly grasp the variation in Δn(xy-z) in the TD direction, and thus it is preferable that the intervals of the measurement positions (centers 10a) of the respective measurement sites 10 be approximately equal intervals.

[0111] In addition, in order to distribute the measurement sites 10 in a wide range in the TD direction, the intervals of the measurement positions (centers 10a) of the adjacent measurement sites 10 with respect to the entire length in the TD direction are preferably set to be at least 1 / 12 or more, more preferably 1 / 10 or more, and most preferably 1 / 8 or more. As for the upper limit of the intervals of the adjacent measurement positions (centers 10a) with respect to the entire length in the TD direction, as long as at least six measurement sites can be set in the TD direction, it is preferably set to be 1 / 5 or less, and more preferably 1 / 6 or less, in consideration of the case where the intervals of the measurement positions (centers 10a) are not equal intervals.

[0112] Further, as shown in Figure 3As shown, when dividing the insulating resin layer of the double-sided metal-coated laminate 100 into two virtual regions A and B with the center line Lo as the boundary of the midpoint of the full length in the TD direction, it is preferable to select the position of each measuring part 10 in such a way that the measuring part 10 existing in each virtual region A and B is located in a position symmetrical about the center line Lo. Figure 3 In the process, with the center line Lo as the reference, three measurement points are set at symmetrical positions in each of the virtual regions A and B, for a total of six measurement points 10. However, four or more measurement points can also be set at symmetrical positions in virtual regions A and B.

[0113] Therefore, the most preferred setting is that the interval between the measurement positions (center 10a) of each measurement part 10 is approximately equal, the interval between adjacent measurement positions (center 10a) is more than 1 / 12 of the total length in the TD direction, and the measurement parts 10 existing in each of the three or more virtual regions A and B are located in positions symmetrical about the center line Lo.

[0114] In addition, such as Figure 3 As shown, it is preferable to set the measurement position (center 10a) of all measurement parts 10 within a range of 49% of the total length from the center line Lo to both ends in the TD direction in each of the two virtual regions A and B. As will be explained later, the reason is that in the manufacturing method of using a pressure roller to heat-press a single-sided metal-coated laminate to a metal foil in a roller-to-roll manner, the variation of Δn(xy-z) near the two ends of the insulating resin layer in the TD direction of the double-sided metal-coated laminate 100 may become large, and the area near the two ends is cut off and not used during circuit processing.

[0115] Therefore, relative to the entire length in the TD direction, from the center line Lo towards both ends, the center 10a of all measuring parts 10 can preferably be set within a range of 0% to 49%, more preferably within a range of 0% to 45%, and most preferably within a range of 0% to 40%. In other words, the center 10a of all measuring parts 10 can be set within a range of 98% after removing preferably 1% from each end area from the entire length in the TD direction, more preferably within a range of 90% after removing 5% from each end area, and most preferably within a range of 80% after removing 10% from each end area.

[0116] Furthermore, since it is not preferable for multiple measurement portions 10 to be biased in the TD direction, the distance between the centers 10a of the two outermost measurement portions 10 among the multiple measurement portions 10 can be set to preferably be 50% or more, more preferably 60% or more, and even more preferably 70% or more relative to the total length in the TD direction.

[0117] According to the above, in order to correctly grasp the deviation of Δn (xy-z) in the TD direction, the plurality of measurement sites 10 can be distributed in such a manner that the distance between the centers 10a of the two outermost measurement sites 10 among the plurality of measurement sites 10 accounts for a range of 50% or more and 98% or less, more preferably a range of 60% or more and 98% or less, and further preferably a range of 70% or more and 98% or less, with respect to the entire length in the TD direction.

[0118] Further, as shown in the following examples, the test piece (sample 20) can also be produced by cutting the test piece from the fragment 100A that is divided into two parts along the center line Lo. In addition, a small fragment in which the both end portions in the TD direction of the fragment 100A are cut off in a range of 1% to 20% can be produced, and the test piece (sample 20) can be further cut from the small fragment. In this case, either end portion of the small fragment in the TD direction can be set as the reference position.

[0119] < Metal Layer >

[0120] As the metal constituting the metal layer, for example, a metal selected from among copper, aluminum, stainless steel, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zirconium, gold, cobalt, titanium, tantalum, zinc, lead, tin, silicon, bismuth, indium, or alloys thereof, or the like can be exemplified. In terms of electrical conductivity, a copper foil is particularly preferable. The copper foil can be any one of an electrolytic copper foil or a rolled copper foil. Further, in the case of continuously producing the two-sided metal-clad laminate 100, as the metal foil, a long metal foil in which a metal foil of a prescribed thickness is wound into a roll shape is used. The length of the metal foil in the TD direction that can be applied to the two-sided metal-clad laminate 100 is, for example, preferably in a range of 500 mm to 1200 mm. The thickness of the metal foil is, for example, preferably in a range of 6 μm to 20 μm, and more preferably in a range of 8 μm to 13 μm. Further, in the two-sided metal-clad laminate 100, the structures of the two metal layers can be the same or different.

[0121] [Manufacturing Method of Two-Sided Copper-Clad Laminate]

[0122] A manufacturing method of the two-sided metal-clad laminate 100 will be described taking a two-sided copper-clad laminate in which the metal layer is a copper layer (copper foil) as an example. In this case, the copper layer laminated on one side of the insulating resin layer of the two-sided copper-clad laminate is referred to as a "first copper layer", and the copper layer laminated on the opposite side is referred to as a "second copper layer".

[0123] (Step of Laminating Insulating Resin Layer on First Copper Layer)

[0124] For example, a single-sided copper-clad laminate in which the insulating resin layer and the first copper foil are laminated, i.e., a single-sided copper-clad laminate in which the width (length in the TD direction) is in the range of 500 mm or more and 1200 mm or less, is formed by the so-called casting method in which, after directly applying a polyamide acid solution to the first copper foil having a width (length in the TD direction) in the range of 500 mm or more and 1200 mm or less, drying and hardening are performed by heat treatment. The first copper foil in the single-sided copper-clad laminate serves as the first copper layer. In the case where the insulating resin layer containing a plurality of polyimide layers is formed by the casting method, the coating liquid of the polyamide acid can be applied sequentially, and drying can be performed to form the precursor layers. For example, in the case where the polyimide layer has a three-layer structure, it is preferable to sequentially apply the coating liquid of the polyamide acid to sequentially laminate the precursor layer of the thermoplastic polyimide, the precursor layer of the non-thermoplastic polyimide, and the precursor layer of the thermoplastic polyimide on the first copper foil, dry the same, and then perform heat treatment to perform imidization. The first copper foil is not particularly limited, and a commercially available rolled copper foil or electrolytic copper foil can be used.

[0125] (Lamination step of second copper layer)

[0126] The single-sided copper-clad laminate having the first copper layer and the long strip-shaped second copper foil prepared separately are passed through the press device having two pairs of press rolls in a manner facing each other in the conveyance step using roll-to-roll. The uncoiling tension of the single-sided copper-clad laminate is preferably in the range of 10 N to 35 N, and more preferably in the range of 15 N to 30 N. The uncoiling tension of the second copper foil is preferably in the range of 5 N to 25 N, and more preferably in the range of 10 N to 20 N. The line speed of the passage is preferably in the range of 2 m / min to 10 m / min. In this way, the second copper foil is laminated by heat pressure bonding using the press rolls on the side of the insulating resin layer of the single-sided copper-clad laminate, and a double-sided copper-clad laminate, i.e., a double-sided copper-clad laminate in which the width (length in the TD direction) is in the range of 500 mm or more and 1200 mm or less, in which the first copper layer is present on one side of the insulating resin layer and the second copper layer is present on the other side, can be obtained. The double-sided copper-clad laminate obtained by pressing is conveyed and wound on the rotating rolls using the winding tension in the roll-to-roll manner, and the balance of the winding tension applied in the TD direction of the double-sided copper-clad laminate can be controlled by adjusting the angle or height of the rotating rolls, and the orientation of the insulating resin layer can be controlled by adjusting the stress applied to the double-sided copper-clad laminate.

[0127] Further, the second copper foil used for the second copper layer is not particularly limited, and can be, for example, a rolled copper foil or an electrolytic copper foil. In addition, the same copper foil as the first copper foil can be used as the second copper foil.

[0128] In the present embodiment, although illustration is omitted, a laminated board obtained by cutting the two-sided metal-clad laminated board 100 in the length direction, the width (length in the TD direction) of which is in the range of 500 mm or more and 1200 mm or less, and making the length in the width direction orthogonal to the length direction, for example, 230 mm or more, preferably 230 mm or more and 450 mm or less, more preferably 230 mm or more and 270 mm or less, and most preferably 230 mm or more and 250 mm or less, can be included as a modification. The divided two-sided metal-clad laminated board of the modification can be manufactured by further cutting the two-sided metal-clad laminated board 100 obtained by the manufacturing method including the laminating process of the first copper layer laminated insulating resin layer and the laminating process of the second copper layer in the length direction, the width of which is in the range of 500 mm or more and 1200 mm or less.

[0129] For the divided two-sided metal-clad laminated board, as long as the thickness direction birefringence is measured at a plurality of measurement sites in the insulating resin layer, the positions in the length direction of which are the same and the positions in the width direction of which are different, that is, at least three measurement sites are provided in the width direction of the insulating resin layer, in a coordinate in which the value of the thickness direction birefringence is set as the vertical axis and the distance in the width direction from an arbitrary reference position in the width direction to each measurement site is set as the horizontal axis, the absolute value of the slope of a straight line obtained by approximating the plotted points corresponding to each measurement site using the least squares method is less than 1 x 10 -5 / mm.

[0130] Although illustration is omitted, in the divided two-sided metal-clad laminated board, if the measurement sites of at least three are deviated in the TD direction, it is difficult to correctly grasp the deviation of Δn (xy-z) in the TD direction, and thus it is preferable that the intervals of the measurement positions of each measurement site are substantially equally spaced.

[0131] In addition, in order to distribute the measurement sites over a wide range in the TD direction, the intervals of the measurement positions of the adjacent measurement sites with respect to the entire length in the TD direction are preferably set to be at least 1 / 6 or more, more preferably 1 / 5 or more, and most preferably 1 / 4 or more. As for the upper limit of the intervals of the adjacent measurement positions, as long as at least three measurement sites in total can be provided in the TD direction, it is preferable that the intervals are set to be 2 / 5 or less, more preferably 1 / 3 or less, with respect to the entire length in the TD direction, taking into account the case where the intervals of the measurement positions are not equally spaced.

[0132] Furthermore, in the divided two-sided metal-clad laminated board, the measurement positions of all the measurement sites can be preferably provided in the range of 49% or less of the entire length in the TD direction from one end to the other end, more preferably in the range of 0% to 45%, and most preferably in the range of 0% to 40%.

[0133] As a preferred example of a split two-sided metal-clad laminate, the following two-sided metal-clad laminate is shown: a two-sided metal-clad laminate 100 with a width of approximately 500 mm is split along the centerline Lo (refer to the centerline Lo) connecting the midpoint of its entire length in the TD direction. Figure 4 A two-section, double-sided metal-clad laminate is formed by cutting it in the length direction and making the length in the width direction, which is orthogonal to the length direction, at least 230 mm, preferably at least 230 mm and less than 250 mm. In this case, it is preferable that when arranging a pair of two-section, double-sided metal-clad laminates with the cut portions joined together and aligning the length direction position with the same position as before cutting, when measuring the birefringence in the thickness direction at multiple measurement points in the insulating resin layer that are at the same position in the length direction but different positions in the width direction—that is, at least three measurement points symmetrically positioned with respect to the cut portion—the absolute value of the slope of the straight line obtained by approximating the plotted points corresponding to each measurement point using the least squares method in a coordinate system where the value of the birefringence in the thickness direction is set as the vertical axis and the distance from any reference position in the width direction to the width direction of each measurement point is set as the horizontal axis, is less than 1 × 10⁻⁶. -5 / mm.

[0134] The modified example described above, which is a split two-sided metal-clad laminate, is the same as the two-sided metal-clad laminate 100 except for the difference in length in the width direction. Therefore, unless otherwise specified, it is included in the two-sided metal-clad laminate 100 of this embodiment.

[0135] [Circuit board]

[0136] The double-sided metal-clad laminate 100 is mainly used as a material for circuit boards such as FPCs. For example, by using conventional methods to process the metal layers of the double-sided metal-clad laminate 100 into a pattern to form wiring layers, circuit boards such as FPCs, which are embodiments of the present invention, multilayer circuit boards formed by stacking the circuit boards into multiple layers, and rigid flexible substrates (rigid FPCs) can be manufactured.

[0137] [Example]

[0138] The following embodiments illustrate the features of the present invention in more detail. However, the scope of the present invention is not limited to these embodiments. Furthermore, in the following embodiments, unless otherwise specified, various measurements and evaluations are performed using the methods described below.

[0139] [Viscosity Measurement]

[0140] The viscosity at 25°C was measured using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro). The rotation speed was set so that the torque was 10% to 90%, and after 2 minutes had elapsed from the start of measurement, the value at the time when the viscosity was stable was read.

[0141] [Measurement of Weight Average Molecular Weight]

[0142] The weight average molecular weight was measured by a gel permeation chromatograph (manufactured by TOSOH Corporation, trade name: HLC-8220 GPC). Polystyrene was used as a standard substance, and N,N-dimethylacetamide was used as a developing solvent.

[0143] [Measurement of Glass Transition Temperature (Tg)]

[0144] Regarding the glass transition temperature, a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F) was used, and a polyimide film having a size of 5 mm x 20 mm was measured at a temperature elevation rate of 4°C / minute and a frequency of 11 Hz from 30°C to 400°C, and the temperature at which the elastic coefficient (tan δ) was the largest was set as the glass transition temperature.

[0145] [Measurement of Coefficient of Thermal Expansion (CTE)]

[0146] A thermomechanical analyzer (manufactured by Bruker, trade name: 4000 SA) was used, and a polyimide film having a size of 3 mm x 20 mm was measured while applying a dead weight of 5.0 g, at a certain temperature elevation rate from 30°C to 265°C, and further, after keeping at the temperature for 10 minutes, was cooled at a rate of 5°C / minute, and the average coefficient of thermal expansion (coefficient of thermal expansion) from 250°C to 100°C was calculated.

[0147] [Measurement of Storage Elastic Coefficient]

[0148] A dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F) was used, and a polyimide film having a size of 5 mm x 20 mm was measured at a temperature elevation rate of 4°C / minute and a frequency of 11 Hz from 30°C to 400°C.

[0149] [Calculation of Birefringence in Thickness Direction (Δn(xy-z))]

[0150] The thickness-direction birefringence Δn(xy-z) was measured using a birefringence meter (manufactured by Photonic Lattice, trade name: wide range birefringence evaluation system WPA-100, measurement region: length direction (MD): 20 mm x width direction (TD): 15 mm). The retardation Re described later was measured using a publicly known polarizing state control device (for example, refer to Patent Document 3), and the thickness-direction birefringence Δn(xy-z) was calculated from the measurement result thereof.

[0151] First, the evaluation method of the retardation Re will be described. Figure 5 is a diagram showing a part of the evaluation system of the retardation Re, Figure 4 is a schematic diagram of the measurement method of the retardation Re.

[0152] The evaluation system of the retardation Re includes a birefringence / phase difference evaluation device (WPA-100 manufactured by Photonic Lattice, Inc.) and a not-shown rotating device for rotating the sample in order to change the incident angle θ1 of light incident to the sample. In Figure 5 , symbol 20 denotes the sample, symbol 21 denotes the light source of the birefringence / phase difference evaluation device, and symbol 22 denotes the light receiving portion of the birefringence / phase difference evaluation device. The wavelength of the light emitted from the light source 21 is 543 nm. The sample 20 is fixed to the not-shown rotating device in a state of being supported by a frame for fixation.

[0153] The retardation Re is measured by changing the incident angle θ1 of light incident to the sample 20 by changing the inclination angle of the sample 20 supported by the frame using the not-shown rotating device (refer to Figure 5 ). The incident angle θ1 is changed to 0°, ±30°, ±40°, ±50°, and the retardation Re is measured at each angle.

[0154] Next, the calculation method of the thickness-direction birefringence Δn(xy-z) will be described. The thickness-direction birefringence Δn(xy-z) is calculated using the measurement result of the retardation Re. In the case where the polyimide film is evaluated using the retardation evaluation system, the incident angle θ1 and the refractive angle θ2 are as shown in Figure 5 . In Figure 3In the diagram, symbol 2 represents a polyimide film containing an insulating resin layer and two metal-coated laminates; symbol 2a represents the laminated surface of polyimide film 2; symbol 2b represents the cast surface of polyimide film 2; and d represents the thickness of the polyimide film. Here, denoted by L1, light is incident on the laminated surface 2a; denoted by L2, light is incident on the polyimide film 2; and denoted by L3, light is emitted from the cast surface 2b. The X, Y, and Z axes are orthogonal. The XY direction is parallel to the laminated surface 2a of the polyimide film 2, and the Z direction is orthogonal to the laminated surface 2a of the polyimide film 2, and is the thickness direction.

[0155] As shown in equation (A) below, the retardation Re depends on the thickness d, the birefringence Δn(xy-z) in the thickness direction, and the angle of refraction θ2. The angle of refraction θ2 depends on the incident angle θ1. Therefore, the birefringence Δn(xy-z) can be calculated from the measured values ​​of the retardation Re obtained for multiple incident angles θ1.

[0156] Re=d·Δn(xy-z)·sin 2 θ² / cosθ²…(A)

[0157] Wherein, the refraction angle θ2 is the angle between the light beam inside the polyimide film 2 and the film normal, and the incident angle θ1 is given by Snell's law as θ2 = sin -1 The relationship between (sinθ1 / N). Here, d is the film thickness, and N is the refractive index of the sample being measured.

[0158] Furthermore, Δn(xy-z) is the difference between the refractive index in the in-plane direction and the refractive index in the thickness direction, and

[0159] It satisfies Δn(xy-z)=Nxy-Nz.

[0160] Nxy: Refractive index in the in-plane direction

[0161] Nz: Refractive index in the thickness direction

[0162] [Evaluation Sample Preparation]

[0163] Two evaluation samples, each 200 mm in length (MD) and 250 mm in width (TD), were cut from a double-sided metal-coated laminate. Measurement sites for birefringence in the thickness direction, obtained using the described method, were established at six locations along the width direction. Each measurement site was a rectangle 20 mm long and 15 mm wide, and the distance from one end of one side of the two side-by-side evaluation samples to the center of each measurement site was defined as the "measurement position."

[0164] Specifically, with a width of 540mm for the double-sided metal-clad laminate, after cutting 20mm off each end to obtain a width of 500mm, along the centerline Lo (refer to...)Figure 6 )A small piece of 2 pieces of evaluation samples cut in the central part in the length direction to a width of 250 mm was prepared by removing the metal layer of each small piece by etching. Two pieces of evaluation films were arranged with the cut parts abutting, and were arranged with the position in the length direction aligned with the same position as before cutting, and were cut into a rectangle of 20 mm in length x 15 mm in width from the end of one film to prepare a sample 20 for thickness direction birefringence in a manner so as to be the measurement position shown in Tables 1, 3, 5, 7, and 9 described later. At this time, 3 each, for a total of 6 samples 20 were produced from positions symmetric in the TD direction with the boundary of the two pieces of evaluation films (corresponding to the original center line Lo) as a reference. The measurement position was set to the center of the sample 20 (the center position of 20 mm in length x 15 mm in width), and the thickness direction birefringence Δn(xy-z) was measured.

[0165] [Measurement of dimensional change rate]

[0166] In the two-sided copper-clad laminate, 2 pieces of evaluation samples were cut to a length direction (MD) of 200 mm x width direction (TD) of 250 mm. Using this sample, as shown in Figure 6 , φ1 mm holes were opened at 2 places in the MD direction at intervals of 100 mm and at 10 places in the TD direction at intervals of 50 mm using an NC drill, and a total of 20 points were formed. Using the sample, the center coordinate positions of the circles were measured using a non-contact computer numerical control (CNC) image measuring machine (manufactured by Mitutoyo, trade name: Quick Vision QV-X404PIL-C). Specifically, 360 points of coordinates were taken at an angle of 1 degree on the circumference of each hole of φ1 mm, and using this 360-point data, the center coordinates of the circles were calculated using the least squares method.

[0167] The copper foils on both sides of the two-sided copper-clad laminate were removed by chemical etching, thereby forming a polyimide film state. After the polyimide film was conditioned at a temperature of 23 degrees and a humidity of 50% RH for 20 hours or more, the center coordinate positions of the circles were again measured using the same device. From the obtained coordinate positions, the distance between the holes adjacent in the MD direction (about 100 mm) was calculated, and the dimensional change rate [%] in the MD direction after etching based on the etching before etching was calculated based on the following calculation formula.

[0168] Calculation formula:

[0169] [(Distance after etching - Distance before etching) ÷ Distance before etching] x 100

[0170] In the case where the length of the width of the two-sided copper-clad laminate was 500 mm, evaluation was performed by dividing into two in the width direction, and for the dimensional change rate in the MD direction, the maximum value and the minimum value were extracted from all the data in the respective width directions, and the difference between them was taken as an index of the deviation (variation range) in the TD direction.

[0171] The abbreviations used in the examples and comparative examples represent the following compounds.

[0172] m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

[0173] TPE-R: 1,3-bis(4-aminophenoxy)benzene

[0174] BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

[0175] PMDA: pyromellitic dianhydride

[0176] BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

[0177] DAPE: 4,4'-diaminodiphenyl ether

[0178] DMAc: N,N-dimethylacetamide

[0179] (Synthetic Example 1)

[0180] Under a stream of nitrogen, 23.0 parts by weight of m-TB (0.108 molar parts) and 3.5 parts by weight of TPE-R (0.012 molar parts) and DMAc in an amount such that the concentration of the solid component after polymerization became 15% by weight were put into a reaction tank, and stirring was performed at room temperature to dissolve them. Next, after 26.0 parts by weight of PMDA (0.119 molar parts) was added, stirring was continued at room temperature for 3 hours to perform a polymerization reaction, and a polyamic acid solution a was obtained. The solution viscosity of the polyamic acid solution a was 41,100 cps. A polyimide film (Tg: 421°C, CTE: 10 ppm / K) of 25 μm in thickness formed from the polyamic acid solution a was non-thermoplastic.

[0181] (Synthetic Example 2)

[0182] Under a stream of nitrogen, 30.2 parts by weight of BAPP (0.074 mole parts) and DMAc in an amount such that the concentration of the solid component after polymerization becomes 15% by weight were put into a reaction vessel, and stirring was performed at room temperature to effect dissolution. Subsequently, 22.3 parts by weight of BPDA (0.076 mole parts) was added, and stirring was continued at room temperature for 3 hours to effect polymerization, and a polyamic acid solution b was obtained. The solution viscosity of the polyamic acid solution b was 9,800 cps. A polyimide film (Tg: 252°C, CTE: 46 ppm / K) having a thickness of 25 μm formed from the polyamic acid solution b was thermoplastic.

[0183] [Example 1]

[0184] On a copper foil 1 (rolled copper foil, long strip, thickness: 12 μm, length in the width direction: 540 mm), the polyamic acid solution b prepared in Synthesis Example 2 was uniformly applied in a hardened thickness of 2.5 μm, and heated and dried at 120°C to remove the solvent. On this, the polyamic acid solution a prepared in Synthesis Example 1 was uniformly applied in a hardened thickness of 20 μm, and heated and dried at 120°C to remove the solvent. Further, on this, the polyamic acid solution b prepared in Synthesis Example 2 was uniformly applied in a hardened thickness of 2.5 μm, and heated and dried at 120°C to remove the solvent. Then, stepwise heat treatment was performed from 130°C to 360°C to complete imidization, and a single-sided copper-clad laminate 1 was prepared. The copper foil 1 was arranged on the face of the polyimide layer in the single-sided copper-clad laminate 1, and hot-press bonding was continuously performed under conditions of a unrolling tension of the single-sided copper-clad laminate 1: 30 N, a roll surface temperature: 300°C to 400°C, a line pressure of the press roll: in the range of 38.6 kgf / cm to 115.8 kgf / cm, and a conveyance speed (line speed) : 4.0 m / min, via a guide roll. With respect to the laminate after hot-press bonding, the width direction tension balance generated by the rotating roll was controlled with a winding tension of 130 N, and thus a double-sided copper-clad laminate 1 was prepared.

[0185] The measurement positions of the birefringence in the thickness direction of the double-sided copper-clad laminate 1 and the calculated values are shown in Table 1.

[0186] [Table 1]

[0187]

[0188] As shown in Table 1, the slope of the approximate straight line calculated from the values of Δn (xy-z) of the 6 points obtained was -4 x 10 -7 / mm.

[0189] Subsequently, the hole marks N1 to N10 and S1 to S10 (refer to Fig. 1) in the double-sided copper-clad laminate 1 were measured with a micrometer, and the thicknesses of the polyimide layers were measured. The results are shown in Table 2. Figure 6The measured values of the hole distance before and after etching and the dimensional change ratio of each are shown in Table 2. Also, the expression in the "hole mark" column in Table 2, for example, if "N1-S1", means the distance between N1 and S1 (the distance between the centers of the holes) in Figure 7 Table 4, Table 6, Table 8, and Table 10.

[0190]

[0191]

[0192] The deviation in the TD direction of the dimensional change ratio in the MD direction after etching from before etching in the two-sided copper-clad laminate 1 was 0.019.

[0193] [Example 2]

[0194] A two-sided copper-clad laminate 2 was prepared in the same manner as in Example 1, except that the copper foil used on both sides was copper foil 2 (rolled copper foil, long strip shape, thickness: 18 μm, length in the width direction: 540 mm).

[0195] The measurement positions of the birefringence in the thickness direction of the two-sided copper-clad laminate 2 and the calculated values are shown in Table 3.

[0196] [Table 3]

[0197]

[0198] As shown in Table 3, the slope of the approximate straight line calculated from the values of Δn (xy-z) of the 6 points was -2 x 10 -6 / mm.

[0199] Next, the measured values of the hole distance before and after etching and the dimensional change ratio of each of the hole marks N1 to N10 and S1 to S10 in the two-sided copper-clad laminate 2 are shown in Table 4.

[0200] [Table 4]

[0201]

[0202] The deviation in the TD direction of the dimensional change ratio in the MD direction after etching from before etching in the two-sided copper-clad laminate 2 was 0.011.

[0203] [Example 3]

[0204] A two-sided copper-clad laminate 3 was prepared in the same manner as in Example 1, except that the copper foil used on both sides was copper foil 2, and the thickness after hardening of the polyamide acid solution b was set to 2.5 μm and the thickness after hardening of the polyamide acid solution a was set to 7 μm.

[0205] The measurement positions of the birefringence in the thickness direction of the two-sided copper-clad laminate 3 and the calculated values are shown in Table 5.

[0206] [Table 5]

[0207]

[0208] As shown in Table 5, the slope of the approximate straight line calculated from the values of Δn (xy-z) of the 6 points was -7 x 10 -6 / mm.

[0209] Next, the measured values of the hole distance before and after etching and the dimensional change ratio of each of the hole marks N1 to N10 and S1 to S10 in the two-sided copper-clad laminate 3 are shown in Table 6.

[0210] [Table 6]

[0211]

[0212] The deviation in the TD direction of the dimensional change ratio in the MD direction after etching with reference to before etching in the two-sided copper-clad laminate 3 was 0.027.

[0213] [Example 4]

[0214] The two-sided copper-clad laminate 4 was prepared in the same manner as in Example 1, except that the copper foil used on both sides was copper foil 3 (electrolytic copper foil, long strip shape, thickness: 12 μm, length in the width direction: 540 mm), and the thickness after hardening of the polyamide acid solution b was set to 2 μm and the thickness after hardening of the polyamide acid solution a was set to 46 μm.

[0215] The measurement positions of the birefringence in the thickness direction of the two-sided copper-clad laminate 4 and the calculated values are shown in Table 7.

[0216] [Table 7]

[0217]

[0218] As shown in Table 7, the slope of the approximate straight line calculated from the values of Δn (xy-z) of the 6 points was -2 x 10 -7 / mm.

[0219] Next, the measured values of the hole distance before and after etching and the dimensional change ratio of each of the hole marks N1 to N10 and S1 to S10 in the two-sided copper-clad laminate 4 are shown in Table 8.

[0220] [Table 8]

[0221]

[0222]

[0223] The deviation of the dimensional change rate in the MD direction after etching with reference to before etching in the two-sided copper-clad laminate 4 was 0.006 in the TD direction.

[0224] (Comparative Example 1)

[0225] The two-sided copper-clad laminate 5 was prepared in the same manner as in Example 1 except that the tension balance in the width direction generated by the rotating roller was not controlled after the hot press bonding.

[0226] The measurement positions of the birefringence in the thickness direction of the two-sided copper-clad laminate 5 and the calculated values are shown in Table 9.

[0227] [Table 9]

[0228]

[0229] As shown in Table 9, the slope of the approximate straight line calculated from the values of Δn(xy-z) of the 6 points was 1 x 10 -5 / mm.

[0230] Next, the measurement values of the hole distance before and after etching and the dimensional change rate of each of the hole signs N1 to N10 and S1 to S10 in the two-sided copper-clad laminate 5 are shown in Table 10.

[0231] [Table 10]

[0232]

[0233] The deviation of the dimensional change rate in the MD direction after etching with reference to before etching in the two-sided copper-clad laminate 5 was 0.062 in the TD direction.

[0234] Figure 7 A graph (vertical axis: dimensional change rate [%], horizontal axis: TD direction position [mm]) comparing the deviation of the dimensional change rate in the MD direction in the TD direction of Example 1 (two-sided copper-clad laminate 1) and Comparative Example 1 (two-sided copper-clad laminate 5) is shown in FIG. 2. Further, the numbers on the horizontal axis of FIG. 2 correspond to the numbers of the hole signs N1 to N10 and S1 to S10 in FIG. 1. Figure 6 ​ The numbers on the horizontal axis of FIG. 2 correspond to the numbers of the hole signs N1 to N10 and S1 to S10 in FIG. 1.

[0235] The above-described embodiments of the present application are described for illustrative purposes, but the present application is not limited to the embodiments and can be variously modified.​

Claims

1. A two-sided metal-clad laminate sheet, which is a long sheet-shaped two-sided metal-clad laminate sheet including an insulating resin layer and metal layers laminated on both sides of the insulating resin layer, characterized in that: the insulating resin layer includes a multilayer polyimide layer having a non-thermoplastic polyimide layer and thermoplastic polyimide layers laminated on both sides of the non-thermoplastic polyimide layer, and a thickness ratio ((A) / (B)) of a thickness (A) of the non-thermoplastic polyimide layer to a thickness (B) of the thermoplastic polyimide layer is 1 to 20, the metal layers are copper layers, and a thickness is 6 μm to 20 μm, the insulating resin layer is first formed on one of the metal layers by a casting method, and the other side of the insulating resin layer is then laminated with the other of the metal layers by heat pressure bonding using a press roll, and then the two-sided copper-clad laminate sheet is produced using a winding tension control to balance a width direction tension generated by a rotating roll, a length in a width direction orthogonal to a length direction of the two-sided metal-clad laminate sheet is 230 mm or more, and a length in the length direction is 1000 mm or more.

2. A two-sided metal-clad laminate sheet, which is a long sheet-shaped two-sided metal-clad laminate sheet including an insulating resin layer and metal layers laminated on both sides of the insulating resin layer, characterized in that: the insulating resin layer includes a multilayer polyimide layer having a non-thermoplastic polyimide layer and thermoplastic polyimide layers laminated on both sides of the non-thermoplastic polyimide layer, and a thickness ratio ((A) / (B)) of a thickness (A) of the non-thermoplastic polyimide layer to a thickness (B) of the thermoplastic polyimide layer is 1 to 20, the metal layers are copper layers, and a thickness is 6 μm to 20 μm, the insulating resin layer is first formed on one of the metal layers by a casting method, and the other side of the insulating resin layer is then laminated with the other of the metal layers by heat pressure bonding using a press roll, and then the two-sided copper-clad laminate sheet is produced using a winding tension control to balance a width direction tension generated by a rotating roll, a length in a width direction orthogonal to a length direction of the two-sided metal-clad laminate sheet is 500 mm or more and 1200 mm or less, and a length in the length direction is 1000 mm or more.

3. The two-sided metal-clad laminate sheet according to claim 1 or 2, wherein a value of a thickness direction birefringence is 0.15 or less at all measurement sites.

4. The two-sided metal-clad laminate sheet according to claim 1 or 2, wherein when the insulating resin layer is divided into two virtual regions with a center line joining a midpoint of a full length in a width direction as a boundary, all measurement sites are set in a range from the center line to 49% of the full length in the width direction in each of the two virtual regions.

5. A circuit substrate, which is produced by processing one or both of the metal layers in the two-sided metal-clad laminate sheet according to claim 1 or 2 into wiring. When measuring the birefringence in the thickness direction at multiple measurement points that are identical in the length direction but different in the width direction within the insulating resin layer, and at least three measurement points are set along the width direction of the insulating resin layer, the absolute value of the slope of the straight line obtained by approximating the plotted points corresponding to each measurement point using the least squares method in a coordinate system where the value of the birefringence in the thickness direction is set as the vertical axis and the distance in the width direction from any reference position to each measurement point is set as the horizontal axis is less than 1 × 10⁻⁶. -5 / mm. ​ ​ ​ ​ ​ When the thickness-direction birefringence is measured at at least three measurement sites provided at positions symmetric with respect to a center line connecting the midpoints of the entire length of the width direction of the insulating resin layer, in a coordinate in which the value of the thickness-direction birefringence is set as the longitudinal axis and the width-direction distance from an arbitrary reference position in the width direction to each measurement site is set as the lateral axis, the absolute value of the slope of a straight line obtained by approximating the plotted points corresponding to each measurement site using the least squares method is less than 1 x 10 -5 / mm. ​ ​ ​

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