JP2023052293A - Metal-clad laminate and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal-clad laminate which can reduce change of a temperature, humidity and a pressure in processes such as a circuit processing step, and dimensional change to change of temperature/humidity environment among processes.

SOLUTION: A metal-clad laminate includes an insulation resin layer and a metal layer, wherein the insulation resin layer has a non-thermoplastic polyimide layer and a thermoplastic polyimide layer, and all the residues contained in the layers are an aromatic tetracarboxylic acid residue and an aromatic diamine residue. The insulation resin layer satisfies (i) in-plane birefringence Δn of 2×10^-3 or less, (ii) variation of Δn in a width direction of 4×10^-4 or less, (iii) a difference between birefringence Δna at 1.5 μm to a central part from one surface and birefringence Δnb at 1.5 μm to the central part from the other surface in a thickness direction of the non-thermoplastic polyimide layer of ±0.01 or less, and (iv) a difference between Δna and Δnb, and an average value of the total of birefringence in the central part in the thickness direction of ±0.01 or less in both Δna and Δnb.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a metal-clad laminate and a circuit board.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, flexible printed circuit boards (FPCs) that are thin, lightweight, flexible, and have excellent durability even after repeated bending have been developed. Circuits are in increasing demand. Since FPC can be mounted three-dimensionally and at high density even in a limited space, it is used for wiring of moving parts of electronic devices such as HDDs, DVDs, mobile phones, and parts such as cables and connectors. expanding.

An FPC is manufactured by etching a copper layer of a copper clad laminate (CCL) and processing the wiring. Rolled copper foil is often used as a material for copper layers in FPCs that are continuously bent or 180° bent in mobile phones and smartphones. For example, Patent Literature 1 proposes that the bending resistance of a copper-clad laminate produced using a rolled copper foil is defined by the number of folds. Further, Patent Document 2 proposes a copper-clad laminate using a rolled copper foil defined by the glossiness and the number of times of bending.

In the photolithography process for copper-clad laminates and the process of FPC mounting, various processes such as bonding, cutting, exposure, and etching are performed based on alignment marks provided on the copper-clad laminates. The processing accuracy in these processes is important for maintaining the reliability of electronic equipment on which the FPC is mounted. However, since the copper-clad laminate has a structure in which a copper layer and a resin layer having different coefficients of thermal expansion are laminated, stress is generated between the layers due to the difference in coefficient of thermal expansion between the copper layer and the resin layer. Part or all of this stress is released when the copper layer is etched to process wiring, causing expansion and contraction, which is a factor in changing the dimensions of the wiring pattern. As a result, a dimensional change finally occurs in the FPC stage, which causes a connection failure between wirings or between wirings and terminals, thereby lowering the reliability and yield of circuit boards. Therefore, dimensional stability is a very important property for copper-clad laminates as circuit board materials. However, in Patent Documents 1 and 2, no consideration is given to the dimensional stability of the copper-clad laminate.

In addition, in Patent Document 3, a flexible metal-clad laminate made of a copper foil and a non-thermoplastic polyimide layer without providing a thermoplastic polyimide layer intentionally in order to lower the thermal expansion coefficient of the insulating resin layer and improve the dimensional stability, As the diamine component of the non-thermoplastic polyimide layer, a diamine compound consisting of p-phenylenediamine (p-PDA) or 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), and 1,3-bis It has been proposed to use a diamine compound such as (4-aminophenoxy)benzene (TPE-R). p-PDA is a monomer that lowers the coefficient of thermal expansion and contributes to dimensional stability, but because of its small molecular weight, there is a problem that the concentration of imide groups increases and the hygroscopicity of polyimide increases. When the hygroscopicity of polyimide becomes high, there is a problem that dimensional change and warpage are likely to occur due to environmental changes such as heating during circuit processing.

On the other hand, Patent Document 4 discloses the use of a combination of m-TB and p-PDA as a diamine compound, which is a raw material for non-thermoplastic polyimide, in a multilayer polyimide film in which the occurrence of cracks during circuit processing is suppressed. ing. However, in the monomer composition of Patent Document 4, since the molar ratio of p-PDA in the diamine compound is too large, the hygroscopicity of the polyimide becomes high in the same manner as described above, resulting in dimensional changes and warping due to environmental changes during circuit processing. is likely to occur. In Patent Document 4, when m-TB, p-PDA and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) are used in combination as diamine compounds, crack resistance is improved. described as worsening. In this case as well, the molar ratio of p-PDA in the diamine compound is too large, and this is considered to cause the problem of increased hygroscopicity of the polyimide, as in the case described above.

Japanese Patent Application Laid-Open No. 2014-15674 (claims, etc.) JP 2014-11451 A (Claims etc.) Japanese Patent No. 5162379 (Claims etc.) WO2016/159104 (Synthesis Example 6, Synthesis Example 9, etc.)

The present invention provides a metal-clad laminate that can reduce dimensional changes due to changes in temperature, humidity and pressure during processes such as circuit processing, substrate lamination and component mounting, as well as temperature and humidity environmental changes between processes. intended to provide

As a result of intensive studies, the present inventors found that the above problems can be solved by controlling the in-plane birefringence (Δn) and the birefringence in the thickness direction of the insulating resin layer, and completed the present invention. came to.

That is, the metal-clad laminate of the present invention is a metal-clad laminate comprising an insulating resin layer and a metal layer laminated on at least one side of the insulating resin layer, wherein the insulating resin layer comprises a non-thermoplastic It has a thermoplastic polyimide layer containing thermoplastic polyimide on at least one side of a non-thermoplastic polyimide layer containing polyimide. The metal-clad laminate of the present invention is characterized in that the insulating resin layer satisfies the following conditions (i) to (iv).
(i) The value of in-plane birefringence (Δn) is 2×10 ⁻³ or less.
(ii) Variation [Δ(Δn)] of in-plane birefringence (Δn) in the width direction (TD direction) is 4×10 ⁻⁴ or less.
(iii) In the thickness direction of the non-thermoplastic polyimide layer, the birefringence (Δna) at a point of 1.5 μm in the central direction from one surface and the central direction from the other surface The difference (Δna-Δnb) from the birefringence index (Δnb) at a point of 1.5 μm is ±0.01 or less.
(iv) The difference from the average value (Δnv) of the total (Δna + Δnb + Δnc) of the Δna and Δnb and the birefringence (Δnc) at the central portion in the thickness direction is ±0.01 for both the Δna and Δnb. be below.

In the metal-clad laminate of the present invention, the non-thermoplastic polyimide contains a tetracarboxylic acid residue and a diamine residue, and 100 mol parts of all diamine residues are represented by the following general formula (1): The diamine residue derived from the compound may be 20 mol parts or more.

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

The metal-clad laminate of the present invention contains 70 diamine residues derived from the diamine compound represented by the general formula (1) per 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. The total amount of diamine residues selected from the following general formulas (2) and (3) may be in the range of 5 to 30 mol parts.

In general formulas (2) and (3), R ₅ , R ₆ , R ₇ and R ₈ are each independently a halogen atom, an alkyl group optionally substituted with a halogen atom having 1 to 4 carbon atoms, or an alkoxy group or an alkenyl group, and X is independently -O-, -S-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -CO-, -COO-, —SO ₂ —, —NH— or —NHCO—, wherein X ₁ and X ₂ are each independently a single bond, —O—, —S—, —CH ₂ —, —CH( CH ₃ )—, —C(CH ₃ ) ₂ —, —CO—, —COO—, —SO ₂ —, —NH— or —NHCO—, but X ₁ and X ₂ are single bonds, and m, n, o and p independently represent an integer of 0 to 4.

In the metal-clad laminate of the present invention, the thermoplastic polyimide contains a tetracarboxylic acid residue and a diamine residue, and from the above general formulas (2) and (3) to 100 mol parts of all diamine residues, The total amount of diamine residues selected may be 50 mole parts or more.

In the metal-clad laminate of the present invention, the diamine residue represented by the general formula (2) may be a diamine residue derived from 1,3-bis(4-aminophenoxy)benzene,
The diamine residue represented by the general formula (3) may be a diamine residue derived from 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

In the metal-clad laminate of the present invention, the thickness ratio (A)/(B) of the thickness (A) of the non-thermoplastic polyimide layer and the thickness (B) of the thermoplastic polyimide layer is in the range of 1 to 20. may

In the metal-clad laminate of the present invention, the length in the width direction (TD direction) may be 490 mm or more.

The circuit board of the present invention is obtained by processing the metal layer of the metal-clad laminate described above into wiring.

Since the metal-clad laminate of the present invention satisfies the conditions (i) to (iv), the dimensional stability of the insulating resin layer is excellent even in a high-temperature/high-pressure environment or in a humidity-changing environment. Problems such as warpage are less likely to occur due to environmental changes (for example, high temperature, high pressure, humidity changes, etc.) during the circuit processing process, substrate lamination process, and component mounting process. In particular, even in a wide metal-clad laminate, the rate of dimensional change is low over the entire width of the insulating resin layer, and the dimensions are stable, so that the FPC obtained from the metal-clad laminate can be mounted at high density. be able to. Therefore, by using the metal-clad laminate of the present invention as an FPC material, it is possible to improve the reliability and yield of circuit boards.

Next, an embodiment of the invention will be described.

<Metal clad laminate>
The metal-clad laminate of the present embodiment includes an insulating resin layer and a metal layer laminated on at least one side of the insulating resin layer.

<Insulating resin layer>
In the metal-clad laminate of the present embodiment, the insulating resin layer has a thermoplastic polyimide layer on at least one of the non-thermoplastic polyimide layers. That is, the thermoplastic polyimide layer is provided on one side or both sides of the non-thermoplastic polyimide layer. For example, in the metal-clad laminate of the present embodiment, the metal layer is laminated on the surface of the thermoplastic polyimide layer.
Here, non-thermoplastic polyimide generally refers to polyimide that does not soften or exhibit adhesiveness when heated. A polyimide having a storage modulus of 1.0×10 ⁹ Pa or more at 360° C. and a storage modulus of 1.0×10 ⁸ Pa or more at 360° C. In addition, thermoplastic polyimide is generally a polyimide whose glass transition temperature (Tg) can be clearly confirmed. In the present invention, the storage modulus at 30 ° C. measured using DMA is 1.0 × 10 ⁹ Pa or more and a storage elastic modulus at 360° C. of less than 1.0×10 ⁸ Pa.

In the metal-clad laminate of the present embodiment, the insulating resin layer satisfies the following conditions (i) to (iv).
(i) The value of in-plane birefringence (Δn) is 2×10 ⁻³ or less.
(ii) Variation [Δ(Δn)] of in-plane birefringence (Δn) in the width direction (TD direction) is 4×10 ⁻⁴ or less.
(iii) In the thickness direction of the non-thermoplastic polyimide layer, the birefringence (Δna) at a point of 1.5 μm in the central direction from one surface and the central direction from the other surface The difference (Δna-Δnb) from the birefringence index (Δnb) at a point of 1.5 μm is ±0.01 or less.
(iv) The difference from the average value (Δnv) of the total (Δna + Δnb + Δnc) of the Δna and Δnb and the birefringence (Δnc) at the central portion in the thickness direction is ±0.01 for both the Δna and Δnb. be below.

Satisfying the above conditions (i) to (iv) enhances the orientation of the polyimide constituting the insulating resin layer, improves the dimensional stability, and suppresses the occurrence of warping.

If the value of the in-plane birefringence (Δn) exceeds 2×10 ⁻³ , the anisotropy of the in-plane orientation becomes large, causing deterioration in dimensional stability. The lower limit of the value of Δn is not particularly limited, but while the in-plane orientation is isotropic and the dimensional stability is improved, the thermal expansion coefficient is excessively lowered, and warping due to mismatch with the thermal expansion coefficient of the metal foil is prevented. From the viewpoint of suppression, it is preferably 2×10 ⁻⁴ or more. From the above point of view, the value of the in-plane birefringence (Δn) of the insulating resin layer is preferably in the range of 2×10 ⁻⁴ or more and 8×10 ⁻⁴ or less, more preferably 2×10 ⁻⁴ or more and 6× It is within the range of 10 ⁻⁴ or less.

Further, if the variation [Δ(Δn)] of Δn in the TD direction exceeds 4×10 ⁻⁴ , the variation in in-plane orientation becomes large, causing in-plane variation in the rate of dimensional change. The variation in Δn in the TD direction [Δ(Δn)] is preferably 2×10 ⁻⁴ or less, more preferably 1.2×10 ⁻⁴ or less. Within such a range, high dimensional accuracy can be maintained even when scaled up, for example.

Further, the difference in birefringence (Δna−Δnb) in the thickness direction of the non-thermoplastic polyimide layer is ±0.01 or less, and the difference (Δnv−Δna ) and the difference (Δnv−Δnb) are both ±0.01 or less, the homogeneity of the polyimide orientation in the thickness direction is enhanced, and the occurrence of warping can be suppressed. The difference (Δnv−Δna) and the difference (Δnv−Δnb) are preferably ±0.008 or less, more preferably ±0.006 or less.

By satisfying the above conditions (i) to (iv), it is possible to effectively prevent dimensional changes and warping due to environmental changes (e.g., high temperature/high pressure environment, humidity change, etc.) during the circuit processing, substrate lamination, and component mounting processes. can be suppressed to If any one of the above conditions (i) to (iv) is not met, the amount of dimensional change will increase due to high temperature, high pressure, humidity changes, etc. during the circuit processing process, board lamination process, and component mounting process. As a result, the dimensional accuracy deteriorates and warping occurs.

When the metal-clad laminate of the present embodiment is applied, for example, as a material for a circuit board, the coefficient of thermal expansion (CTE) of the insulating resin layer is set to 10 ppm/K in order to prevent warping and deterioration of dimensional stability. It is important to be within the range of 30 ppm/K or more, preferably 10 ppm/K or more and 25 ppm/K or less. If the CTE is less than 10 ppm/K or more than 30 ppm/K, warping will occur and dimensional stability will decrease. Further, in the metal-clad laminate of the present embodiment, the CTE of the insulating resin layer with respect to the CTE of the metal layer made of copper foil or the like is more preferably within a range of ±5 ppm/K or less, and more preferably ±2 ppm/K or less. Within the range is most preferred.

In the insulating resin layer, the non-thermoplastic polyimide layer constitutes a low thermal expansion polyimide layer, and the thermoplastic polyimide layer constitutes a high thermal expansion polyimide layer. Here, the low thermal expansion polyimide layer preferably has a coefficient of thermal expansion (CTE) in the range of 1 ppm/K or more and 25 ppm/K or less, more preferably 3 ppm/K or more and 25 ppm/K or less. say. Further, the high thermal expansion polyimide layer preferably has a CTE of 35 ppm/K or more, more preferably 35 ppm/K or more and 80 ppm/K or less, still more preferably 35 ppm/K or more and 70 ppm/K or less. layer. The polyimide layer can be made into a polyimide layer having a desired CTE by appropriately changing the combination of raw materials to be used, thickness, and drying/curing conditions.

The thickness of the insulating resin layer can be set within a predetermined range depending on the purpose of use. is more preferred. If the thickness of the insulating resin layer is less than the above lower limit, there may occur problems such as the inability to ensure electrical insulation and the deterioration of handling properties, making it difficult to handle in the manufacturing process. On the other hand, when the thickness of the insulating resin layer exceeds the above upper limit, it is necessary to control the manufacturing conditions with high accuracy in order to control the in-plane birefringence (Δn) and the birefringence in the thickness direction (Δn). There is a problem such as a decrease in productivity.

Further, in the insulating resin layer, the thickness ratio ((A)/(B)) of the thickness (A) of the non-thermoplastic polyimide layer and the thickness (B) of the thermoplastic polyimide layer is within the range of 1 to 20. is preferred, and in the range of 2 to 12 is more preferred. In addition, when the number of layers of a non-thermoplastic polyimide layer and/or a thermoplastic polyimide layer is plural, thickness (A) and thickness (B) mean the total thickness. If the value of this ratio is less than 1, the non-thermoplastic polyimide layer becomes thin with respect to the entire insulating resin layer, so the in-plane birefringence (Δn) tends to vary greatly. Since the thickness is reduced, the reliability of adhesion between the insulating resin layer and the metal layer tends to be lowered. Here, the control of the in-plane birefringence (Δn) is correlated with the resin composition and thickness of each polyimide layer constituting the insulating resin layer. The thermoplastic polyimide layer, which is a resin structure imparted with adhesiveness, that is, high thermal expansion or softening, greatly affects the value of Δn of the insulating resin layer as the thickness thereof increases. Therefore, it is preferable to increase the thickness ratio of the non-thermoplastic polyimide layer and decrease the thickness ratio of the thermoplastic polyimide layer to reduce the value of Δn of the insulating resin layer and its variation. As will be described later, in the present embodiment, even when the thickness ratio of the thermoplastic polyimide layer is reduced, the thermoplastic polyimide layer contains a predetermined amount of diamine residues selected from general formulas (2) and (3) Adhesiveness between the metal layer and the insulating resin layer can be ensured by designing as follows.

From the viewpoint of enhancing the effect of improving the dimensional accuracy of the insulating resin layer, the length (film width) in the width direction (TD direction) of the metal-clad laminate of the present embodiment is preferably in the range of 490 mm or more and 1200 mm or less. More preferably, it is in the range of 520 mm or more and 1100 mm or less, and the length of the elongated shape is preferably 20 m or more. When the metal-clad laminate of the present embodiment is continuously produced, the wider the width direction (TD direction), the more remarkable the effect of the invention. After the metal-clad laminate of the present embodiment is continuously produced, the long metal-clad laminate is slit in the longitudinal direction (MD direction) and the TD direction at a certain value. is also included.

In addition, the insulating resin layer preferably has a tensile modulus of 3.0 to 10.0 GPa, more preferably 4.5 to 8.0 GPa, when formed into a polyimide film. If the tensile modulus of elasticity of the polyimide film is less than 3.0 GPa, the strength of the polyimide itself decreases, resulting in handling problems such as tearing of the insulating resin layer when processing the metal-clad laminate into a circuit board. may occur. On the other hand, if the tensile modulus of elasticity of the polyimide film exceeds 10.0 GPa, the rigidity against bending of the metal-clad laminate increases, resulting in an increase in the bending stress applied to the metal wiring when the metal-clad laminate is bent. and the bending resistance is lowered. By setting the tensile elastic modulus of the polyimide film within the above range, the strength and flexibility of the insulating resin layer can be ensured.

(non-thermoplastic polyimide)
In the present embodiment, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer contains a tetracarboxylic acid residue and a diamine residue, both of which preferably contain an aromatic group. Both the tetracarboxylic acid residue and the diamine residue contained in the non-thermoplastic polyimide contain an aromatic group, making it easier to form an ordered structure of the non-thermoplastic polyimide, and the insulating resin layer in a high-temperature environment. By reducing the amount of change in the in-plane birefringence (Δn), variations in the in-plane birefringence (Δn) can be suppressed, and changes in the birefringence in the thickness direction can be suppressed.

In the present invention, the tetracarboxylic acid residue represents a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue represents a divalent group derived from a diamine compound. represents In addition, in the "diamine compound", hydrogen atoms in two terminal amino groups may be substituted, for example, -NR ₃ R ₄ (wherein R ₃ and R ₄ are independently arbitrary groups such as alkyl groups). (meaning a substituent).

The tetracarboxylic acid residue contained in the non-thermoplastic polyimide is not particularly limited, but for example, a tetracarboxylic acid residue derived from pyromellitic dianhydride (PMDA) (hereinafter also referred to as PMDA residue). ) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) (hereinafter also referred to as BPDA residue). These tetracarboxylic acid residues easily form an ordered structure, and can reduce the amount of change in in-plane birefringence (Δn) in a high-temperature environment and suppress the change in birefringence in the thickness direction. can. In addition, PMDA residues are residues that play a role in controlling the coefficient of thermal expansion and controlling the glass transition temperature. Furthermore, since the BPDA residue does not have a polar group among the tetracarboxylic acid residues and has a relatively large molecular weight, it can be expected to have the effect of reducing the imide group concentration of the non-thermoplastic polyimide and suppressing the moisture absorption of the insulating resin layer. From such a viewpoint, the total amount of PMDA residues and/or BPDA residues is preferably 50 mol parts or more, more preferably 100 mol parts of all tetracarboxylic acid residues contained in the non-thermoplastic polyimide. is in the range of 50 to 100 mol parts, most preferably in the range of 70 to 100 mol parts.

Other tetracarboxylic acid residues contained in the non-thermoplastic polyimide include, for example, 2,3′,3,4′-biphenyltetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic acid Acid dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 2,2',3,3'-, 2,3,3 ',4'- or 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-diphenyl ether tetracarboxylic dianhydride, bis(2,3-dicarboxy phenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyl tetra Carboxylic dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3.4-dicarboxyphenyl)methane dianhydride , bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7 ,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 2,2- bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4, 5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene- 1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4,5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride anhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic acid Tetracarboxylic acid residues derived from aromatic tetracarboxylic acid dianhydrides such as dianhydrides and 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydrides.

The diamine residue contained in the non-thermoplastic polyimide preferably includes a diamine residue derived from the diamine compound represented by the general formula (1).

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

A diamine residue derived from a diamine compound represented by the general formula (1) (hereinafter sometimes referred to as "diamine residue (1)") easily forms an ordered structure, increases dimensional stability, In particular, it is possible to effectively suppress the change in the in-plane birefringence (Δn) and the change in the birefringence in the thickness direction under a high-temperature environment. From such a viewpoint, the diamine residue (1) is 20 mol parts or more, preferably in the range of 70 to 95 mol parts, per 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. It is preferably contained within the range of 80 to 90 mol parts.

Preferred specific examples of the diamine residue (1) include 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 other diamine residues derived from diamine compounds. Among these, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) is particularly easy to form an ordered structure, and the amount of change in in-plane birefringence (Δn) in a high-temperature environment is It is particularly preferable because it can be made small and the change in birefringence in the thickness direction can be suppressed.

In addition, in order to reduce the elastic modulus of the insulating resin layer and improve the elongation and bending resistance, etc., the non-thermoplastic polyimide is selected from the group consisting of diamine residues represented by the following general formulas (2) and (3). It preferably contains at least one selected diamine residue.

In the above formulas (2) and (3), R ₅ , R ₆ , R ₇ and R ₈ are each independently a halogen atom, an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, or an alkoxy group or an alkenyl group, and X is independently -O-, -S-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -CO-, -COO-, —SO ₂ —, —NH— or —NHCO—, wherein X ₁ and X ₂ are each independently a single bond, —O—, —S—, —CH ₂ —, —CH( CH ₃ )—, —C(CH ₃ ) ₂ —, —CO—, —COO—, —SO ₂ —, —NH— or —NHCO—, but X ₁ and X ₂ are single bonds, and m, n, o and p independently represent an integer of 0 to 4.
The term “independently” refers to multiple linking groups X, linking groups X ₁ and X ₂ , multiple substituents R ₅ , in one or both of the above formulas (2) and (3). It means that R ₆ , R ₇ , R ₈ as well as the integers m, n, o, p may be the same or different.

Since the diamine residues represented by the general formulas (2) and (3) have flexible sites, they can impart flexibility to the insulating resin layer. Here, since the diamine residue represented by the general formula (3) has four benzene rings, in order to suppress an increase in the coefficient of thermal expansion (CTE), the terminal group bonded to the benzene ring is positioned at the para position. It is preferable to In addition, from the viewpoint of suppressing an increase in the coefficient of thermal expansion (CTE) while imparting flexibility to the insulating resin layer, the diamine residues represented by the general formulas (2) and (3) are included in the non-thermoplastic polyimide. It is preferably contained in the range of 5 to 30 mol parts, more preferably in the range of 10 to 20 mol parts, per 100 mol parts of the total diamine residues. If the diamine residue represented by the general formulas (2) and (3) is less than 5 mol parts, the elastic modulus of the insulating resin layer increases, the elongation decreases, and the bending resistance and the like may decrease. However, if it exceeds 30 mol parts, the orientation of the molecules may deteriorate, making it difficult to lower the CTE.

In the diamine residue represented by the general formula (2), one or more of m, n and o is preferably 0, and preferred examples of the groups R ₅ , R ₆ and R ₇ are An alkyl group optionally substituted with 1 to 4 halogen atoms, an alkoxy group having 1 to 3 carbon atoms, or an alkenyl group having 2 to 3 carbon atoms can be mentioned. In general formula (2), preferable examples of the linking group X include -O-, -S-, -CH ₂ -, -CH(CH ₃ )-, -SO ₂ - or -CO-. can be done. Preferred specific examples of the diamine residue represented by the general formula (2) include 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 Diamine residues derived from diamine compounds such as -(4-aminophenyl)-2-propyl]benzene and 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene can be mentioned.

In the diamine residue represented by the general formula (3), one or more of m, n, o and p is preferably 0, and preferred examples of the groups R ₅ , R ₆ , R ₇ and R ₈ Examples thereof include an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, an alkoxy group having 1 to 3 carbon atoms, and an alkenyl group having 2 to 3 carbon atoms. In general formula (3), preferred examples of the linking groups X ₁ and X ₂ include a single bond, —O—, —S—, —CH ₂ —, —CH(CH ₃ )—, and —SO ₂ — or -CO-. However, from the viewpoint of providing a bending portion, the case where both the linking groups _X1 and _X2 are single bonds is excluded. Preferred specific examples of the diamine residue represented by the general formula (3) include 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 other diamine compounds. and diamine residues.

Among the diamine residues represented by the general formula (2), diamine residues derived from 1,3-bis(4-aminophenoxy)benzene (TPE-R) (referred to as "TPE-R residues" ) is particularly preferred, and among the diamine residues represented by the general formula (3), a diamine residue derived from 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) (sometimes referred to as "BAPP residue") is particularly preferred. Since the TPE-R residue and the BAPP residue have flexible sites, they can reduce the elastic modulus of the insulating resin layer and impart flexibility. In addition, since the BAPP residue has a large molecular weight, it can be expected to have the effect of reducing the imide group concentration of the non-thermoplastic polyimide and suppressing the moisture absorption of the insulating resin layer.

Other diamine residues contained in the non-thermoplastic polyimide include, for example, m-phenylenediamine (m-PDA), 4,4'-diaminodiphenyl ether (4,4'-DAPE), 3,3'-diaminodiphenyl ether , 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane , 3,4′-diaminodiphenylpropane, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfone, 3,3′ -diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[ 4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)phenyl]methane , bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)]benzophenone, 9,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 2,2- Bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'- diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl) ether, bis(p-β -methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2 ,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m -derived from aromatic diamine compounds such as xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole and piperazine and diamine residues.

In the non-thermoplastic polyimide, by selecting the types of the tetracarboxylic acid residue and the diamine residue, and the respective molar ratios when applying two or more types of tetracarboxylic acid residues or diamine residues, thermal expansion Modulus, storage modulus, tensile modulus, etc. can be controlled. In addition, when the non-thermoplastic polyimide has a plurality of structural units of polyimide, it may be present as blocks or randomly, but from the viewpoint of suppressing variations in in-plane birefringence (Δn) , preferably randomly.

The imide group concentration of the non-thermoplastic polyimide is preferably 35% by weight or less. Here, "imide group concentration" means a value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 35% by weight, the molecular weight of the resin itself becomes small, and the low hygroscopicity deteriorates due to the increase in polar groups. By selecting the combination of the acid anhydride and the diamine compound, the orientation of the molecules in the non-thermoplastic polyimide is controlled, thereby suppressing the increase in CTE due to the decrease in the imide group concentration and ensuring low hygroscopicity. ing.

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

(thermoplastic polyimide)
In the present embodiment, the thermoplastic polyimide constituting the thermoplastic polyimide layer contains a tetracarboxylic acid residue and a diamine residue, both of which preferably contain an aromatic group. Both the tetracarboxylic acid residue and the diamine residue contained in the thermoplastic polyimide contain an aromatic group, thereby suppressing the amount of change in the in-plane birefringence (Δn) of the insulating resin layer in a high-temperature environment. At the same time, the change in birefringence in the thickness direction can be suppressed.

The tetracarboxylic acid residue contained in the thermoplastic polyimide is not particularly limited, but for example, a tetracarboxylic acid residue derived from pyromellitic dianhydride (PMDA) (hereinafter also referred to as PMDA residue). , 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) (hereinafter also referred to as BPDA residue). These tetracarboxylic acid residues easily form an ordered structure, and can reduce the amount of change in in-plane birefringence (Δn) in a high-temperature environment and suppress the change in birefringence in the thickness direction. can. In addition, PMDA residues are residues that play a role in controlling the coefficient of thermal expansion and controlling the glass transition temperature. Furthermore, since the BPDA residue does not have a polar group among the tetracarboxylic acid residues and has a relatively large molecular weight, it can be expected to have the effect of reducing the imide group concentration of the thermoplastic polyimide and suppressing the moisture absorption of the insulating resin layer. From such a viewpoint, the total amount of PMDA residues and/or BPDA residues is preferably 50 mol parts or more, more preferably 100 mol parts of all tetracarboxylic acid residues contained in the thermoplastic polyimide. It should be in the range of 50 to 100 mole parts, most preferably in the range of 70 to 100 mole parts.

Other tetracarboxylic acid residues contained in the thermoplastic polyimide include tetracarboxylic acid residues derived from aromatic tetracarboxylic dianhydrides similar to those exemplified for the non-thermoplastic polyimides.

In the present embodiment, the diamine residue contained in the thermoplastic polyimide is preferably at least one diamine residue selected from general formulas (2) and (3). The diamine residue selected from the general formulas (2) and (3) is preferably 50 mol parts or more in total, and preferably 50 to 100 mol parts, with respect to 100 mol parts of all diamine residues. More preferably, it is within the range of 70 to 100 mole parts. By including a total of 50 mol parts or more of diamine residues selected from general formulas (2) and (3) with respect to 100 mol parts of all diamine residues, the thermoplastic polyimide layer has flexibility and adhesiveness. can be applied and act as an adhesion layer to the metal layer. Among diamine residues represented by general formula (2), TPE-R residues are particularly preferred, and among diamine residues represented by general formula (3), BAPP residues are particularly preferred. Since the TPE-R residue and the BAPP residue have flexible sites, they can reduce the elastic modulus of the insulating resin layer and impart flexibility. In addition, since the BAPP residue has a large molecular weight, it can be expected to have the effect of reducing the imide group concentration of the thermoplastic polyimide and suppressing the moisture absorption of the insulating resin layer.

Further, as described above, when the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer contains a diamine residue selected from the general formulas (2) and (3), the thermoplastic polyimide layer is constituted The thermoplastic polyimide should also contain, as the diamine residue, a similar structure, preferably a diamine residue of the same kind selected from general formulas (2) and (3). In this case, the thermoplastic polyimide and the non-thermoplastic polyimide have different content ratios of diamine residues. , the orientation control of the thermoplastic polyimide layer and the non-thermoplastic polyimide layer becomes easy, and the dimensional accuracy becomes easy to manage. From this point of view, in the present embodiment, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer and the thermoplastic polyimide constituting the thermoplastic polyimide layer are both from the above general formulas (2) and (3) It preferably contains at least one selected diamine residue, and most preferably the diamine residue contains a TPE-R residue and/or a BAPP residue.

In the present embodiment, diamine residues other than those represented by general formulas (2) and (3) contained in the thermoplastic polyimide include, for example, 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), 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'-bisamino)diphenylamine, 1, 4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzenamine, 3-[3-(4-aminophenoxy)phenoxy]benzenamine, 1,3-bis(3 -aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline , 4,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline, 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)]bisaniline, bis[4-( 4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK), bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-amino phenoxy)]biphenyl and other diamine residues derived from diamine compounds.

In the thermoplastic polyimide, by selecting the types of the tetracarboxylic acid residues and diamine residues, and the respective molar ratios when applying two or more types of tetracarboxylic acid residues or diamine residues, the thermal expansion coefficient , tensile modulus, glass transition temperature, etc. can be controlled. Further, when the thermoplastic polyimide has a plurality of structural units of polyimide, it may exist as a block or may exist randomly, but it is preferable to exist randomly.

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

The imide group concentration of the thermoplastic polyimide is preferably 35% by weight or less. Here, "imide group concentration" means a value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 35% by weight, the molecular weight of the resin itself becomes small, and the low hygroscopicity deteriorates due to the increase in polar groups. By selecting the combination of the acid anhydride and the diamine compound, the orientation of the molecules in the thermoplastic polyimide is controlled, thereby suppressing the increase in CTE due to the decrease in the imide group concentration and ensuring low hygroscopicity. there is

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

(Synthesis of non-thermoplastic polyimide and thermoplastic polyimide)
In general, polyimide can be produced by reacting a tetracarboxylic dianhydride and a diamine compound in a solvent to produce a polyamic acid, followed by heating and ring closure. For example, a tetracarboxylic dianhydride and a diamine compound are dissolved in an organic solvent in approximately equimolar amounts and stirred at a temperature within the range of 0 to 100° C. for 30 minutes to 24 hours for a polymerization reaction to form a polyimide precursor. A polyamic acid is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the resulting precursor is within the range of 5 to 30% by weight, preferably within the range of 10 to 20% by weight. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2 -butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, cresol and the like. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such an organic solvent used is not particularly limited, but the amount used is adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 30% by weight. is preferred.

It is usually advantageous to use the synthesized polyamic acid as a reaction solvent solution, but if necessary, it can be concentrated, diluted, or replaced with another organic solvent. Polyamic acid is also advantageously used because it is generally excellent in solvent solubility. The viscosity of the polyamic acid solution is preferably in the range of 500 cps to 100,000 cps. If the thickness is out of this range, defects such as thickness unevenness and streaks are likely to occur in the film during the coating operation using a coater or the like. The method for imidizing the polyamic acid is not particularly limited, and for example, a heat treatment such as heating in the solvent at a temperature within the range of 80 to 400° C. for 1 to 24 hours is preferably employed.

<Metal layer>
Metals constituting the metal layer include, for example, copper, aluminum, stainless steel, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zirconium, gold, cobalt, titanium, tantalum, zinc, lead, tin, silicon, and bismuth. , indium or alloys thereof. Although the metal layer can be formed by a method such as sputtering, vapor deposition, or plating, it is preferable to use a metal foil from the viewpoint of adhesiveness. Copper foil is particularly preferable in terms of conductivity. The copper foil may be either electrolytic copper foil or rolled copper foil. In the case of continuously producing the metal-clad laminate of the present embodiment, a long metal foil having a predetermined thickness wound into a roll is used as the metal foil.

Hereinafter, a copper-clad laminate having a copper layer will be described as a preferred embodiment of the metal-clad laminate.

<Copper clad laminate>
The copper-clad laminate of the present embodiment may have an insulating layer and a copper layer such as a copper foil on at least one surface of the insulating layer. Further, in order to improve the adhesiveness between the insulating layer and the copper layer, the layer in contact with the copper layer in the insulating layer is a thermoplastic polyimide layer. A copper layer is provided on one side or both sides of the insulating layer. That is, the copper-clad laminate of the present embodiment may be a single-sided copper-clad laminate (single-sided CCL) or a double-sided copper-clad laminate (double-sided CCL). In the case of single-sided CCL, the copper layer laminated on one side of the insulating layer is referred to as the "first copper layer" in the present invention. In the case of double-sided CCL, the copper layer laminated on one side of the insulating layer is referred to as the "first copper layer" in the present invention, and in the insulating layer, on the side opposite to the side on which the first copper layer is laminated, Let the laminated|stacked copper layer be the "2nd copper layer" in this invention. The copper-clad laminate of the present embodiment is used as an FPC after forming a copper wiring by etching the copper layer to form a wiring circuit.

Copper-clad laminates may be prepared, for example, by preparing a resin film, sputtering metal onto it to form a seed layer, and then forming a copper layer, for example, by copper plating.

Alternatively, the copper-clad laminate may be prepared by preparing a resin film and laminating a copper foil thereon by a method such as thermocompression bonding.

Furthermore, the copper clad laminate is formed by casting a coating liquid containing polyamic acid, which is a precursor of polyimide, on the copper foil, drying it to form a coating film, and then imidizing it by heat treatment to form a polyimide layer. It may be prepared by

(first copper layer)
In the copper clad laminate of the present embodiment, the copper foil used for the first copper layer (hereinafter sometimes referred to as "first copper foil") is not particularly limited. Rolled copper foil or electrolytic copper foil may be used.

The thickness of the first copper foil is preferably 13 μm or less, more preferably within the range of 6 to 12 μm. If the thickness of the first copper foil exceeds 13 μm, the bending stress applied to the copper layer (or copper wiring) when the copper clad laminate (or FPC) is bent increases, resulting in a decrease in bending resistance. Become. Also, from the viewpoint of production stability and handling properties, the lower limit of the thickness of the first copper foil is preferably 6 μm.

Also, the tensile modulus of elasticity of the first copper foil is, for example, preferably in the range of 10 to 35 GPa, more preferably in the range of 15 to 25 GPa. When a rolled copper foil is used as the first copper foil in the present embodiment, it tends to be highly flexible when annealed by heat treatment. Therefore, if the tensile modulus of elasticity of the copper foil is less than the above lower limit, the rigidity of the first copper foil itself is lowered by heating in the step of forming the insulating layer on the long first copper foil. . On the other hand, if the tensile elastic modulus exceeds the above upper limit, a large bending stress is applied to the copper wiring when the FPC is bent, and the bending resistance is lowered. Note that the rolled copper foil tends to change its tensile modulus depending on the heat treatment conditions when forming the insulating layer on the copper foil, the annealing treatment of the copper foil after forming the insulating layer, and the like. Therefore, in the present embodiment, the tensile modulus of elasticity of the first copper foil in the finally obtained copper-clad laminate should be within the above range.

The first copper foil is not particularly limited, and commercially available rolled copper foil can be used.

(Second copper layer)
The second copper layer is laminated on the surface of the insulating layer opposite to the first copper layer. The copper foil (second copper foil) used for the second copper layer is not particularly limited, and may be, for example, a rolled copper foil or an electrolytic copper foil. A commercially available copper foil can also be used as the second copper foil. The same copper foil as the first copper foil may be used as the second copper foil.

<Circuit board>
The metal-clad laminate of the present embodiment is mainly useful as a material for circuit boards such as FPC. For example, a circuit board such as an FPC according to one embodiment of the present invention can be manufactured by patterning the copper layer of the copper-clad laminate exemplified above to form a wiring layer by a conventional method.

EXAMPLES Examples are given below to more specifically describe the features of the present invention. However, the scope of the present invention is not limited to the examples. In the following examples, unless otherwise specified, various measurements and evaluations are as follows.

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

[Measurement of glass transition temperature (Tg)]
For the glass transition temperature, a polyimide film having a size of 5 mm × 20 mm was measured using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F), and the temperature was increased from 30 ° C. to 400 ° C. Measurement was performed at 4° C./min and a frequency of 11 Hz, and the temperature at which the change in elastic modulus (tan δ) was maximum was taken as the glass transition temperature. "Thermoplastic" means that the storage modulus at 30°C measured using DMA is 1.0 × 10 ⁹ Pa or more and the storage modulus at 360°C is less than 1.0 × 10 ⁸ Pa. A material having a storage modulus of 1.0×10 ⁹ Pa or more at 30° C. and a storage modulus of 1.0×10 ⁸ Pa or more at 360° C. was defined as “non-thermoplastic”.

[Measurement of coefficient of thermal expansion (CTE)]
A polyimide film with a size of 3 mm × 20 mm is heated from 30 ° C. to 265 ° C. at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). Further, after holding at that temperature for 10 minutes, it was cooled at a rate of 5°C/min, and the average thermal expansion coefficient (thermal expansion coefficient) from 250°C to 100°C was obtained.

[Measurement of in-plane retardation (RO)]
Using a birefringence meter (manufactured by Photonic Lattice, trade name; wide range birefringence evaluation system WPA-100, measurement area; MD: 140 mm × TD: 100 mm), obtain the retardation in the in-plane direction of a given sample. rice field. The incident angle is 0° and the measurement wavelength is 543 nm.

[Preparation of sample for evaluation of in-plane retardation (RO)]
A4 size (TD: 210 mm × MD: 297 mm) to prepare sample L (Left), sample R (Right) and sample C (Center).

[Evaluation of in-plane birefringence (Δn)]
In-plane retardation (RO) of each of sample L, sample R and sample C was measured. The value obtained by dividing the maximum measured value of each sample by the thickness of the evaluation sample is defined as "in-plane birefringence (Δn)", and the difference between the maximum and minimum measured values of in-plane retardation (RO) is "In-plane retardation (RO) variation (ΔRO) in the width direction (TD direction)", and the value obtained by dividing this ΔRO by the thickness of the evaluation sample is the "in-plane birefringence in the width direction (TD direction) ( Δn) variation [Δ(Δn)]”.

[Measurement of thickness direction retardation and birefringence]
For the polyimide layer as the insulating resin layer, a 0.5 μm-thick thin slice was prepared by an ultramicrotome, and the retardation in the thickness direction was measured. At this time, a birefringence meter (manufactured by Photonic Lattice, trade name; birefringence distribution observation camera PI-micro for attachment to a microscope) was used. The measurement wavelength is 520 nm and the incident angle is 0°.
ROa is a retardation value at a point of 1.5 μm in the central direction from one surface of the non-thermoplastic polyimide layer in the polyimide layer (film).
ROb is a retardation value at a point of 1.5 μm in the central direction from the other surface of the non-thermoplastic polyimide layer in the polyimide layer (film).
ROv is the average value of the total (ROa+ROb+ROc) of the retardation values (ROc) at the central portion in the thickness direction of the non-thermoplastic polyimide layer in the polyimide layer (film), as well as ROa.
In addition, the value obtained by dividing the value of ROa by the thickness of the thin film section (0.5 μm) is “In the thickness direction of the non-thermoplastic polyimide layer, at a point of 1.5 μm in the central direction based on one surface The value obtained by dividing the value of ROb by the thickness of the thin film section (0.5 μm) is defined as the “birefringence index (Δna)”, and the value is “in the thickness direction of the non-thermoplastic polyimide layer, the center direction with the other surface as the base point. The birefringence index (Δnb) at a point of 1.5 μm is defined as the value obtained by dividing the value of ROc by the thickness of the thin film section (0.5 μm), which is the birefringence at the center in the thickness direction of the non-thermoplastic polyimide layer. refractive index (Δnc)”.
Δnv is the average value of the sum of Δna, Δnb and Δnc (Δna+Δnb+Δnc).

[Warpage measurement]
A polyimide film having a size of 50 mm×50 mm was subjected to humidity conditioning at 23° C. and 50% RH for 24 hours. The curl amount at that time was measured using a vernier caliper. At this time, when the film curled toward the etching surface of the base material, it was expressed as a plus, and when it curled toward the opposite surface, it was expressed as a minus.

[Measurement of peel strength]
After processing the copper foil of the single-sided copper-clad laminate (copper foil/resin layer) to a width of 1.0 mm, it was cut into a width of 8 cm and a length of 4 cm to prepare a measurement sample. Using a Tensilon tester (manufactured by Toyo Seiki Seisakusho, trade name: Strograph VE-1D), the resin layer side of the measurement sample is fixed to an aluminum plate with double-sided tape, and the copper foil is placed in a 90 ° direction at a speed of 50 mm / min. , the central strength was obtained when the copper foil was peeled off from the resin layer by 10 mm.

The abbreviations used in Examples and Comparative Examples represent the following compounds.
PMDA: pyromellitic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1 ,3-bis(4-aminophenoxy)benzene DAPE: 4,4′-diaminodiphenyl ether BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane p-PDA: p-phenylenediamine DMAc: N ,N-dimethylacetamide

(Synthesis example 1)
Under a nitrogen stream, 23.0 parts by weight of m-TB (0.108 mol parts) and 3.5 parts by weight of TPE-R (0.012 mol parts) were added to the reactor, and the solid content concentration after polymerization was 15% by weight of DMAc was added and stirred at room temperature to dissolve. Next, after adding 26.0 parts by weight of PMDA (0.119 mol parts), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to obtain a polyamic acid solution a. The solution viscosity of polyamic acid solution a was 41,100 cps. The polyimide obtained from this polyamic acid solution a had a glass transition temperature of 421° C., was non-thermoplastic, and had a thermal expansion coefficient of 10 (ppm/K).

(Synthesis example 2)
Under a nitrogen stream, 17.3 parts by weight of m-TB (0.081 mol part) and 10.2 parts by weight of TPE-R (0.035 mol part) and the solid content concentration after polymerization were added to the reaction vessel. 15% by weight of DMAc was added and stirred at room temperature to dissolve. Next, after adding 25.1 parts by weight of PMDA (0.115 mol parts), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to obtain a polyamic acid solution b. The solution viscosity of polyamic acid solution b was 38,200 cps. The polyimide obtained from this polyamic acid solution b had a glass transition temperature of 427° C., was non-thermoplastic, and had a thermal expansion coefficient of 22 (ppm/K).

(Synthesis Example 3)
Under a nitrogen stream, 16.4 parts by weight of m-TB (0.077 mol parts) and 9.7 parts by weight of TPE-R (0.033 mol parts) and the solid content concentration after polymerization were added to the reactor. 15% by weight of DMAc was added and stirred at room temperature to dissolve. Next, after adding 16.7 parts by weight of PMDA (0.077 parts by weight) and 9.7 parts by weight of BPDA (0.033 parts by weight), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours, A polyamic acid solution c was obtained. The solution viscosity of polyamic acid solution c was 46,700 cps. The polyimide obtained from this polyamic acid solution c had a glass transition temperature of 366° C., was non-thermoplastic, and had a thermal expansion coefficient of 23 (ppm/K).

(Synthesis Example 4)
Under a nitrogen stream, 22.4 parts by weight of m-TB (0.105 mol parts) and 4.8 parts by weight of BAPP (0.012 mol parts) and a post-polymerization solids concentration of 15 parts by weight were added to the reactor. % DMAc was added and dissolved by stirring at room temperature. Next, after adding 25.3 parts by weight of PMDA (0.116 mol part), the mixture was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain a polyamic acid solution d. The solution viscosity of polyamic acid solution d was 36,800 cps. The polyimide obtained from this polyamic acid solution d had a glass transition temperature of 408° C., was non-thermoplastic, and had a thermal expansion coefficient of 9 (ppm/K).

(Synthesis Example 5)
Under a stream of nitrogen, 12.3 parts by weight of m-TB (0.058 mol), 10.1 parts by weight of TPE-R (0.035 mol) and 2.5 parts by weight of p - PDA (0.023 mol part) and DMAc in an amount so that the solid content concentration after polymerization was 15% by weight were added and dissolved by stirring at room temperature. Next, after adding 17.5 parts by weight of PMDA (0.080 mol part) and 10.1 parts by weight of BPDA (0.034 mol part), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours, A polyamic acid solution e was obtained. The solution viscosity of the polyamic acid solution e was 42,700 cps. The polyimide obtained from this polyamic acid solution e had a glass transition temperature of 360° C., was non-thermoplastic, and had a thermal expansion coefficient of 18 (ppm/K).

(Synthesis Example 6)
Under a nitrogen stream, 2.2 parts by weight of m-TB (0.010 mol parts) and 27.6 parts by weight of TPE-R (0.094 mol parts) were added to the reactor, and the solid content concentration after polymerization was 15% by weight of DMAc was added and stirred at room temperature to dissolve. Next, after adding 22.7 parts by weight of PMDA (0.104 mol part), the mixture was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain a polyamic acid solution f. The solution viscosity of the polyamic acid solution f was 33,900 cps. The polyimide obtained from this polyamic acid solution f had a glass transition temperature of 446° C., a thermoplasticity and a thermal expansion coefficient of 55 (ppm/K).

(Synthesis Example 7)
Under a nitrogen stream, 30.2 parts by weight of BAPP (0.074 mol part) and DMAc in an amount so that the solid content concentration after polymerization is 15% by weight are added to the reactor, and stirred at room temperature to dissolve. rice field. Next, after adding 22.3 parts by weight of BPDA (0.076 mol part), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to obtain polyamic acid solution g. The solution viscosity of the polyamic acid solution g was 9,800 cps. The polyimide obtained from this polyamic acid solution g had a glass transition temperature of 252° C., a thermoplasticity and a thermal expansion coefficient of 46 (ppm/K).

(Synthesis Example 8)
Under a nitrogen stream, 25.8 parts by weight of TPE-R (0.088 mol part) and DMAc in an amount so that the solid content concentration after polymerization is 15% by weight are charged into the reactor, and stirred at room temperature. Dissolved. Next, after adding 26.7 parts by weight of BPDA (0.091 mol part), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to obtain a polyamic acid solution h. The solution viscosity of the polyamic acid solution h was 8,800 cps. The polyimide obtained from this polyamic acid solution h had a glass transition temperature of 243° C., a thermoplasticity and a thermal expansion coefficient of 65 (ppm/K).

(Synthesis Example 9)
Under a nitrogen stream, 17.6 parts by weight of TPE-R (0.060 mol parts) and 1.6 parts by weight of p-PDA (0.015 mol parts) were added to the reactor, and the solid content concentration after polymerization was 15% by weight of DMAc was added and stirred at room temperature to dissolve. Next, after adding 22.8 parts by weight of BPDA (0.077 mol parts), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to obtain a polyamic acid solution i. The solution viscosity of the polyamic acid solution i was 7,800 cps. The polyimide obtained from this polyamic acid solution i had a glass transition temperature of 239° C., a thermoplasticity and a thermal expansion coefficient of 65 (ppm/K).

(Synthesis Example 10)
Under a nitrogen stream, 11.7 parts by weight of DAPE (0.058 mol parts) and 11.4 parts by weight of TPE-R (0.039 mol parts) and a post-polymerization solids concentration of 15 parts by weight were added to the reactor. % DMAc was added and dissolved by stirring at room temperature. Next, after adding 29.5 parts by weight of BPDA (0.100 mol part), the mixture was stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain a polyamic acid solution j. The solution viscosity of polyamic acid solution j was 11,200 cps. The polyimide obtained from this polyamic acid solution j had a glass transition temperature of 265° C., a thermoplasticity and a thermal expansion coefficient of 58 (ppm/K).

[Example 1]
After uniformly applying the polyamic acid solution g prepared in Synthesis Example 7 to one side of a long electrodeposited copper foil having a thickness of 12 μm and a width of 1,080 mm so that the thickness after curing is 2.5 μm (first layer), and dried by heating at 120° C. to remove the solvent. The polyamic acid solution a prepared in Synthesis Example 1 was evenly coated thereon so that the thickness after curing was 20 μm (second layer), and then dried by heating at 120° C. to remove the solvent. Further, the polyamic acid solution g prepared in Synthesis Example 7 was uniformly applied thereon so that the thickness after curing was 2.5 μm (third layer), and then dried by heating at 120° C. to remove the solvent. . After that, stepwise heat treatment was performed from 130° C. to 360° C. to complete imidization, and a single-sided copper-clad laminate was prepared.

[Examples 2 to 8 and Comparative Examples 1 to 3]
After coating a polyamic acid resin solution on one side of the electrolytic copper foil, heat drying and stepwise heat treatment are performed to prepare a single-sided copper-clad laminate. A single-sided copper-clad laminate was obtained in the same manner as in Example 1, except that the configuration was changed to that shown in Table 1 below.

Table 1 shows the thickness ratio (non Thermoplastic polyimide layer (A) / thermoplastic polyimide layer (B)), in-plane retardation (RO), in-plane retardation (RO) variation (ΔRO) in the width direction (TD direction) and thickness of non-thermoplastic polyimide layer The difference in retardation in the vertical direction (|ROa-ROb|, |ROv-ROa|, |ROv-ROb|), the amount of warpage, and the peel strength are shown. In addition, Table 2 shows the in-plane birefringence (Δn) and the in-plane birefringence in the width direction (TD direction) of the insulating resin layers of the single-sided copper-clad laminates obtained in Examples 1 to 8 and Comparative Examples 1 to 3. variation [Δ(Δn)] in the index (Δn) and the difference in birefringence (|Δna−Δnb|, |Δnv−Δna|, |Δnv−Δnb|) in the thickness direction of the non-thermoplastic polyimide layer.

<IC chip mountability>
A dry film is laminated on the copper foil surface of the single-sided copper-clad laminates prepared in Examples 1 to 8 and Comparative Examples 1 to 3, and after patterning the dry film resist, the copper foil is etched along the pattern to form a circuit. was formed to prepare a circuit board. An IC chip was mounted on the copper wiring side of the obtained circuit board by bonding at 400° C. for 0.5 seconds. did not occur. On the other hand, in Comparative Example 1, misalignment occurred between the copper wiring and the IC chip, and in Comparative Examples 2 and 3, misalignment between the copper wiring and the IC chip and warping of the circuit board occurred, which caused problems in mounting. occurred.

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

Claims (7)

A metal-clad laminate comprising an insulating resin layer and a metal layer laminated on at least one side of the insulating resin layer,
The insulating resin layer has a thermoplastic polyimide layer containing a thermoplastic polyimide on at least one surface of the non-thermoplastic polyimide layer containing a non-thermoplastic polyimide,
The tetracarboxylic acid residues and diamine residues contained in the non-thermoplastic polyimide and the thermoplastic polyimide are both aromatic tetracarboxylic acid residues and aromatic diamine residues,
The total amount of diamine residues selected from the following general formulas (2) and (3) with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide is within the range of 5 to 30 mol parts can be,
The total amount of diamine residues selected from the following general formulas (2) and (3) is 50 mol parts or more with respect to 100 mol parts of all diamine residues contained in the thermoplastic polyimide,

[In general formulas (2) and (3), R ₅ , R ₆ , R ₇ and R ₈ are each independently a halogen atom or an alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom. or an alkoxy group or an alkenyl group, and X is independently -O-, -S-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -CO-, -COO -, -SO ₂ -, -NH- or -NHCO-, wherein X ₁ and X ₂ are each independently a single bond, -O-, -S-, -CH ₂ -, - a divalent group selected from CH(CH ₃ )—, —C(CH ₃ ) ₂ —, —CO—, —COO—, —SO ₂ —, —NH— or —NHCO—, but X ₁ and m, n, o and p independently represent an integer of 0 to 4, except when both of _X2 are single bonds. ]
The insulating resin layer satisfies the following conditions (i) to (iv);
(i) the value of in-plane birefringence (Δn) is 2×10 ⁻³ or less;
(ii) variation [Δ(Δn)] of in-plane birefringence (Δn) in the width direction (TD direction) is 4×10 ⁻⁴ or less;
(iii) In the thickness direction of the non-thermoplastic polyimide layer, the birefringence (Δna) at a point of 1.5 μm in the central direction from one surface and the central direction from the other surface The difference (Δna-Δnb) from the birefringence index (Δnb) at a point of 1.5 μm is ±0.01 or less;
(iv) the difference from the average value (Δnv) of the total (Δna + Δnb + Δnc) of the Δna and Δnb and the birefringence index (Δnc) at the central portion in the thickness direction is ±0.01 for both the Δna and Δnb; be:
A metal-clad laminate characterized by satisfying A diamine residue derived from a diamine compound represented by the following general formula (1) is 20 mol parts or more with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. The metal-clad laminate according to claim 1.

[In the general formula (1), the linking group Z represents a single bond or -COO-, and Y is independently a monovalent hydrocarbon having 1 to 3 carbon atoms which may be substituted with a halogen atom or a phenyl group, or a It represents an alkoxy group having 1 to 3 carbon atoms, a perfluoroalkyl group having 1 to 3 carbon atoms, or an alkenyl group, n represents an integer of 0 to 2, and p and q independently represent an integer of 0 to 4. ] The diamine residue derived from the diamine compound represented by the general formula (1) is in the range of 70 mol parts to 95 mol parts with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. The metal-clad laminate according to claim 2, characterized in that: The diamine residue represented by the general formula (2) is a diamine residue derived from 1,3-bis(4-aminophenoxy)benzene,
2. According to claim 1, wherein the diamine residue represented by the general formula (3) is a diamine residue derived from 2,2-bis[4-(4-aminophenoxy)phenyl]propane. A metal clad laminate as described. The thickness ratio (A) / (B) of the thickness (A) of the non-thermoplastic polyimide layer and the thickness (B) of the thermoplastic polyimide layer is in the range of 1 to 20. A metal clad laminate as described. 2. The metal-clad laminate according to claim 1, wherein the length in the width direction (TD direction) is 490 mm or more. A circuit board obtained by processing the metal layer of the metal-clad laminate according to any one of claims 1 to 6 into wiring.