CN116367413A

CN116367413A - Metal-clad laminate and circuit board

Info

Publication number: CN116367413A
Application number: CN202211660418.6A
Authority: CN
Inventors: 池田知弥; 王宏远
Original assignee: Nippon Steel and Sumikin Chemical Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2021-12-27
Filing date: 2022-12-23
Publication date: 2023-06-30
Also published as: JP2023097390A

Abstract

The invention provides a metal-clad laminate and a circuit board, wherein the metal-clad laminate has low haze and excellent visibility and light transmittance, and the hue of L or a is regulated. A metal-clad laminate comprising a metal layer on one or both surfaces of an insulating resin layer, wherein the thickness of the insulating resin layer is in the range of 10 to 100 μm, the total light transmittance is 50% or more, the haze is 70% or less, and when the surface of the metal layer in contact with the insulating resin layer is measured through the insulating resin layer, l×a×b is 50 or less and l×a is 9 or less in a color system.

Description

Metal-clad laminate and circuit board

Technical Field

The present invention relates to a metal-clad laminate and a circuit board each including an insulating resin layer and a metal layer.

Background

In recent years, along with the progress of miniaturization, weight saving, and space saving of electronic devices, there has been an increasing demand for flexible printed wiring boards (Flexible Printed Circuits, FPC) which are thin and lightweight, have flexibility, and have excellent durability even when repeatedly bent. Since FPC can be mounted in a three-dimensional and high-density manner even in a limited space, its use is expanding to parts such as wires of movable parts of electronic devices such as Hard Disk Drives (HDD), digital optical discs (digital video disk, DVD), smart phones, and cables and connectors. Most FPCs are manufactured by forming a circuit on a metal layer formed by laminating a metal layer using a metal foil or the like and a metal-clad laminate having an insulating resin base (insulating resin layer).

Since FPCs, particularly FPCs having excellent transparency, are characterized by being thin, lightweight, bendable, and non-breakable, there has been an increasing demand for substrate applications in the field where the installation of LED transparent displays including large-sized electro-optical boards and light emitting diodes (light emitting diode, LEDs) is expected, in recent years, as "glass antennas" that are used as transparent antennas and are formed on the surface of glass panes to base the windows, as techniques for embedding antennas in displays for mobile applications, or as techniques for embedding antennas in displays. In such a new application, a method of forming a thin wiring which is difficult to be seen by the naked eye is known, but since visibility of a substrate is particularly required, it is strongly demanded to make the presence of the wiring as inconspicuous as possible when the wiring after processing is observed from the opposite side (from the side where the user views (the insulating resin layer side)) of the film. The reason for this is that the contrast of the display may be lowered due to regular reflection of the wiring. Moreover, in this field, the current situation is: copper-clad laminates in which copper foil is sputtered onto polyethylene terephthalate (polyethylene terephthalate, PET) as an insulating resin layer have been partially used in terms of cost, transparency, and the like, but there is room for further investigation in terms of long-term reliability such as light resistance and the like.

Here, a metal-clad laminate suitable for a transparent FPC has been proposed, but in order to ensure visibility/transparency of an insulating resin layer (insulating resin layer at a portion where a metal layer is etched) to be used, a metal layer having less roughening may be suitably used as a metal layer present on the surface (for example, patent document 1). The reason for this is that the surface profile such as the surface roughness of the metal layer in the insulating resin layer after the metal layer is etched is continued to the resin layer side.

In addition, since the surface of the metal having less roughening is smooth, the occurrence of scattering of light is small, and reflection (regular reflection) of light tends to be increased, and thus there is a concern that the gloss, color tone, and presence of the metal used are stronger and more noticeable.

Therefore, when the metal is applied to a substrate for such applications, it is not necessary to consider the reflection, color tone, and the like of the metal itself, but it is important to consider the actual use and adjust the hue (sense of presence) of the metal layer when viewed from the opposite side (from the side where the user views (the insulating resin layer side)) of the film.

Furthermore, the following techniques have been previously disclosed, namely: in FPCs, touch panels, and the like, as roughened copper foil, a technique in which a copper foil having a luminance L value of 30 or less is blackened is used in particular in consideration of transparency of a film after copper foil etching, visibility of wiring, and the like (for example, patent document 2); in the use of wiring boards, a technique of roughening with pure copper to reduce diffuse reflectance in consideration of adhesion and visibility after formation of a circuit pattern (for example, patent document 3) has been disclosed, which is a technique of: in the touch panel, a technique of providing a transparent adhesive layer having a predetermined roughened surface on the contact surface of a transparent substrate and a copper foil (for example, patent document 4), but none of these techniques has been studied for applications in which the presence of extremely fine wiring such as an LED transparent display is considered.

[ Prior Art literature ]

[ patent literature ]

[ patent document 1] International publication No. WO 2020/26450

[ patent document 2] International publication No. WO2014/133164

[ patent document 3] Japanese patent No. 5706026

Patent document 4 Japanese patent laid-open No. 2015-157392

Disclosure of Invention

[ problem to be solved by the invention ]

Accordingly, the inventors of the present application have further studied a resin film or a metal-clad laminate, which have been studied before, from the above point of view, and as a result, have found that the following method is adopted: the present invention has been accomplished by solving the above-mentioned problems by providing a metal having a roughened surface with a surface roughness characteristic in a specific range and having an L value and an a value of an L-b color system adjusted to a specific range for a metal layer, and preferably suppressing as much as possible the increase in HAZE (HAZE).

Accordingly, an object of the present invention is to provide a metal-clad laminate in which the haze (haze) of an insulating resin layer is low, visibility and light transmittance are excellent, and the hue of L or a is adjusted.

[ means of solving the problems ]

Namely, the present invention is as follows.

[1] A metal-clad laminate having a metal layer on one or both surfaces of an insulating resin layer, characterized in that,

the thickness of the insulating resin layer is in the range of 9-100 μm, the total light transmittance is more than 50%, the haze is less than 70%,

when the surface of the metal layer in contact with the insulating resin layer is measured through the insulating resin layer, l×a×b is 50 or less and a is 9 or less in the color system.

[2] The metal-clad laminate according to [1], wherein L x a x b x the L x of the color system in the metal layer is 60 or less and a x is 15 or less.

[3] The metal-clad laminate according to [1], wherein when the surface of the metal layer in contact with the insulating resin layer is measured through the insulating resin layer, the reflectance at 680nm is 50% or less.

[4] The metal-clad laminate according to [1], wherein the total light transmittance of the insulating resin layer is 75% or more.

[5] The metal-clad laminate according to [1], wherein the insulating resin layer has a haze of 10% or less.

[6] The metal-clad laminate according to [1], wherein the 1% weight reduction temperature in the insulating resin layer is 450 ℃ or higher.

[7] The metal-clad laminate according to [1], wherein the solder heat resistance is 200 ℃ or higher.

[8] The metal-clad laminate according to [1], wherein 180 ° tear strength between the insulating resin layer and the metal layer is 0.3kN/m or more.

[9] The metal-clad laminate according to [1], wherein the thickness of the metal layer is in the range of 1 μm to 25 μm.

[10] A circuit board obtained by wiring the metal layer of the metal-clad laminate according to any one of [1] to [9 ].

[ Effect of the invention ]

The present invention provides a metal-clad laminate which has low haze and excellent visibility and light transmittance of an insulating resin layer, and which has an adjusted L or a hue. The metal-clad laminate of the present invention is suitable for applications requiring high transparency, such as glass antennas, antennas for mobile displays, or substrates for LED transparent displays, because the hue of the metal layer is adjusted so as to be less noticeable.

Detailed Description

Hereinafter, embodiments of the present invention will be described.

< Metal clad laminate >)

The metal-clad laminate of the present invention comprises: the insulating resin layer and the metal layer laminated on at least one surface of the insulating resin layer may have a metal layer on one side of the insulating resin layer or may have a metal layer on both sides of the insulating resin layer.

In the metal-clad laminate of the present invention, the reflected light L x a x b x of the color system is 50 or less and the reflected light L x a x of the color system is 9 or less when the surface of the metal layer of the metal-clad laminate, which is in contact with the insulating resin layer, is measured through the insulating resin layer (insulating-resin layer). In this case, the reflected light measured is not limited to the reflected light from the surface of the metal layer alone, and the reflected light from the insulating resin layer is not excluded. That is, in the present invention, it is important to consider the L value of reflected light measured when the metal layer is observed through the insulating resin layer assuming actual use. Further, regarding the l×a×b color system, according to japanese industrial standard (Japanese industrial standards, JIS) Z8781-4-:2013, and measuring. The L, a, and b values measured at this time are measured at a viewing angle of 2 ° or 10 ° using a D65 light source (JISZ 8720 standard illuminant of sunlight) or a C light source (JISZ 8720 auxiliary illuminant of sunlight) used for displaying a daylight-illuminated object color. Specifically, as shown in examples described later, after the mirror surface side of the metal layer of the metal-clad laminate (single-sided) was attached to the glass plate, light was irradiated from the insulating resin layer side, and the reflected light reflected from the surface of the metal layer via the insulating resin layer was measured at a viewing angle of 2 °, so that the values of L, a, and b at this time were measured.

Here, L is an index indicating brightness, but in the metal-clad laminate of the present invention, it is desirable to suppress reflection of the metal layer to make it inconspicuous, so that it is necessary to make L black relatively low to suppress gloss, and it is necessary that L measured by the above method is 50 or less. Preferably 45 or less, more preferably 40 or less. On the other hand, the lower limit value is not particularly limited, but is preferably 10 or more, and is preferably 20 or more, more preferably 25 or more, still more preferably 30 or more, and most preferably more than 30, in view of the ease of adjusting the balance between black and film transparency.

In addition, the a represents +a represents the red direction and the a represents the chromaticity in the green direction. In the metal-clad laminate of the present invention, copper (copper foil) is often used as the metal layer, and the reflected light on the copper surface is often a large and reddish tone. Further, since the reddish tone tends to be noticeable to the human eye, in consideration of these, the value of a is small and halation is suppressed, and a is required to be 9 or less in the present invention. Preferably, a is 6 or less, more preferably 5 or less. On the other hand, the lower limit value is not particularly limited, but if the negative value of a increases, the greenish tone increases as described above, and therefore is preferably-10 or more, more preferably-5 or more, and further preferably-2 or more.

In this case, b is not particularly limited, but +b represents the yellow direction and-b represents the chromaticity in the blue direction, and thus the numerical value (absolute value) is preferably small, and the upper limit is preferably 15 or less, more preferably 12 or less, and further preferably 10 or less. On the other hand, it is preferable that: the lower limit is preferably-15 or more, more preferably-5 or more, and still more preferably 0 or more.

In the metal-clad laminate of the present invention, as described above, the presence of the metal layer is preferably inconspicuous when viewed through the insulating resin layer, and therefore, it is preferable that the light reflectance from the surface of the metal layer measured through the insulating resin layer in the same manner is low. Further, as described, it is not excluded that the reflected light includes reflected light caused by the insulating resin layer. Specifically, as described above, when copper (copper foil) is used as the metal layer, the reflectance of the reddish tone is preferably small, and the reflectance of 680nm, which is the wavelength of red light, is preferably 50% or less. More preferably 30% or less, and still more preferably 20% or less. On the other hand, the lower limit value is not particularly limited since it is desirably not reflected. The reflectance measurement method is preferably performed by the method described in examples.

< Metal layer >)

The material of the metal layer is not particularly limited, and examples thereof include: copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, alloys of these, and the like. Among them, a metal element of copper, iron or nickel, or Indium Tin Oxide (ITO) is preferable, and copper (copper foil) is more preferable. As the copper foil, either an electrolytic copper foil or a rolled copper foil can be used. In addition, when these metal layers are selected, characteristics required for the purpose of use such as conductivity of the metal layer, light transmittance of the polyimide layer, adhesion to the polyimide layer, and the like are selected so as to be exhibited. The shape of the metal layer is not particularly limited, but may be processed or the like as appropriate according to the application. It is suitable to use a roll formed in a long shape.

The thickness of the metal layer is not particularly limited, but is preferably 100 μm or less, more preferably in the range of 0.1 μm to 50 μm, and still more preferably in the range of 1 μm to 25 μm.

In addition, from the viewpoints of light transmittance of the insulating resin layer, color tone of the metal layer, sharpness of an image when used as a display, and the like, it is preferable that the surface roughness Ra of the surface of the metal layer is preferably 0.01 μm or more and 0.1 μm or less, more preferably 0.01 μm or more and 0.07 μm or less, and still more preferably 0.01 μm or more and 0.03 μm or less. The surface roughness Rz is preferably 0.06 μm or more and 0.5 μm or less, more preferably 0.1 μm or more and 0.4 μm or less, and still more preferably 0.1 μm or more and 0.3 μm or less. By setting the Ra and Rz of the surface of the metal layer to the above ranges, the haze value of the insulating resin layer after etching the metal layer can be made low, which is preferable.

The metal layer is preferably a metal layer in which L, a, and b of the color system are defined as the predetermined ranges, but L, a, and b of the metal layer measured with the insulating resin layer interposed therebetween may be defined as the predetermined ranges. As shown in examples described below, L, a, and b of the metal layer were obtained by using the metal layer alone and attaching the mirror surface side to a glass plate, and then using the same measurement method as that of the metal-clad laminate (single-sided).

The L of the metal layer is preferably 60 or less, more preferably 55 or less, and even more preferably 53 or less. On the other hand, the lower limit of L is preferably 10 or more, more preferably more than 30, still more preferably 40 or more, and most preferably 45 or more. The metal layer having a low L is preferred because the brightness of the metal is reduced and is not noticeable when viewed through the transparent film.

The metal layer a is preferably 15 or less, more preferably 10 or less, and even more preferably 8 or less. On the other hand, the lower limit of a is preferably 1 or more, more preferably 2 or more, and further preferably 3 or more.

The metal layer b is preferably 15 or less, more preferably 13 or less, and further preferably 12 or less, and the lower limit is preferably 2 or more, more preferably 5 or more, and further preferably 7 or more.

For the same reason as described above, the metal layer itself preferably has a low light reflectance on its surface, and particularly, it is conceivable that copper (copper foil) is used as the metal layer, and the reflectance at 680nm as red light is preferably 50% or less. More preferably 35% or less, and still more preferably 30% or less. On the other hand, the lower limit value is not particularly limited since it is desirably not reflected. The reflectance measurement method is preferably performed by the method described in examples.

< insulating resin layer >)

The insulating resin layer of the present invention needs to have at least a degree of light transmittance such that the position of the metal layer can be recognized/viewed through the insulating resin layer, and the total light transmittance is required to be 50% or more. Preferably, the transparent film is more nearly transparent, and the total light transmittance is preferably 70% or more, more preferably 75% or more.

In view of such visibility/transparency, the haze (haze) of the insulating resin layer (insulating resin layer after etching the metal layer) is required to be 70% or less, preferably 60% or less, more preferably 40% or less, further preferably 30% or less, further more preferably 10% or less, and most preferably 5% or less. The lower limit is not limited, but is preferably 0.5% or more, more preferably 0.8% or more, and still more preferably 1% or more.

The thickness of the insulating resin layer is set to be in the range of 9 μm to 100 μm in terms of processability, conveyability, and supportability of the film itself in the process. The film may be appropriately selected depending on the application and the like, but is preferably 9 to 70 μm, more preferably 9 to 50 μm, in terms of the transparency of the film.

In view of the fact that the larger the surface roughness of the insulating resin layer is, the more the haze is deteriorated when light is irradiated, and the lower the visibility of the display is, the surface roughness Ra of the insulating resin layer is preferably 0.01 μm or more and 0.1 μm or less, more preferably 0.01 μm or more and 0.07 μm or less, and still more preferably 0.01 μm or more and 0.03 μm or less. The surface roughness Rz is preferably 0.06 μm or more and 0.5 μm or less, more preferably 0.1 μm or more and 0.4 μm or less, and still more preferably 0.1 μm or more and 0.3 μm or less.

The Yellowness (YI) of the insulating resin layer is preferably 60 or less, more preferably 50 or less, further preferably 40 or less, and most preferably 30 or less. For example, it is preferable that the thickness of the insulating resin layer is 25 μm. By controlling the range to be such, the insulating resin layer can be made substantially colorless. On the other hand, when YI is out of the above-described range, the coloring of yellow to yellow brown is strong, and the visibility of the insulating resin layer tends to be low, but may be appropriately selected depending on the application or the like.

The insulating resin layer is not particularly limited and may be appropriately selected according to the application. Preferable examples include: polyethylene terephthalate (PET), polyethylene naphthalate (polyethylene naphthalate, PEN), liquid crystal polymers (liquid crystal polymer, LCP), perfluoroalkoxyalkane (PFA) resins, polymethyl methacrylate, cyclic olefin polymers, polycarbonate, polyimide (PI), and the like. Among them, polyimide is preferably used in terms of excellent heat resistance, adhesion, flexibility, and the like, and also excellent transparency depending on the composition.

Further, as long as the object of the present invention is not hindered, an inorganic filler may be contained in the insulating resin layer as necessary. Specifically, examples thereof include: silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, and the like. These may be used singly or in combination of two or more.

First, an embodiment when polyimide is used will be described as an example of a preferable insulating resin layer of the present invention.

The polyimide (polyimide layer) used may be a commercially available polyimide film as it is, but is not particularly limited, and may be formed by the following method, etc. as a method for forming a polyimide layer as an insulating resin layer: for example, [1] a method of producing a resin film by coating a solution of polyamic acid on a supporting substrate (for example, a metal layer) and drying the same, and then imidizing the same (hereinafter, casting method); [2] and a method for producing a resin film by coating a polyamic acid solution on a support substrate, drying the coating, peeling off a gel film of the polyamic acid from the support substrate, and imidizing the peeled gel film. In the case where the insulating resin layer includes a plurality of polyimide layers, examples of the mode of the production method include the following methods: [3] a method of coating a polyamic acid solution on a support substrate and drying the same and then imidizing the same (hereinafter, a sequential coating method) is repeated a plurality of times; [4] a method of simultaneously coating a laminated structure of polyamic acid on a support substrate by multilayer extrusion, drying the laminated structure, and then imidizing the laminated structure (hereinafter, referred to as a multilayer extrusion method).

The insulating resin layer (metal-clad laminate) is preferably formed by a casting method-sequential coating method in terms of dimensional stability, adhesion between the insulating resin layer and the metal layer, haze of the insulating resin layer after etching the metal layer, or control of in-plane retardation.

The method of applying the polyimide solution (or the polyamic acid solution) to the substrate is not particularly limited, and may be applied by, for example, a coater such as a bevel wheel, a die, a doctor blade, or a lip. In forming the multilayered polyimide layer, a method in which an operation of applying a polyimide solution (or a polyamic acid solution) on a substrate and drying is repeated is preferable. The polyimide layer may be formed of only a single layer, but when considering adhesion of the polyimide layer to the metal layer or the like, it is preferable to include a plurality of layers.

In the case of a plurality of polyimide layers, the polyimide layer (P1) directly laminated on the metal layer and the polyimide layer (P2) not directly laminated on the metal layer may be two-layer structure. As exemplified in structures 1 to 4 below, three layers are preferable, and the third polyimide layer (P3) is more preferable to be laminated in the order of (P1)/(P2)/(P3). M1 and M2 represent metal layers, and M1 and M2 may be the same or different. The polyimide layer (P1) directly laminated on the metal layer and the third polyimide layer (P3) may have the same composition. For example, when a plurality of polyimide layers are formed by casting, a two-layer structure in which a polyimide layer (P1) directly laminated on a metal layer from the casting surface side and a polyimide layer (P2) not directly laminated on a conductor layer are laminated in this order may be formed, or a three-layer structure in which a polyimide layer (P1) directly laminated on a conductor layer from the casting surface side, a polyimide layer (P2) not directly laminated on a conductor layer, and a third polyimide layer (P3) are laminated in this order may be formed. The "casting surface" herein means a surface on the support side when the polyimide layer is formed. The support may be a metal layer of the metal-clad laminate of the present invention, may be glass or the like, or may be a support for forming a gel film or the like. The surface of the plurality of polyimide layers on the side opposite to the casting surface is referred to as a "lamination surface", and if not described, the metal layers may be laminated on the lamination surface, or may not be laminated.

Structure 1; M1/P1/P2

A structure 2; M1/P1/P2/P1 (or P3)

A structure 3; M1/P1/P2/P1 (or P3)/M2 (or M1)

A structure 4; M1/P1/P2/P1 (or P3)/M2 (or M1)

The polyimide constituting the polyimide layer (P1) and the polyimide layer (P3) is preferably a thermoplastic polyimide, and is preferably used as an adhesive layer to a metal layer by improving adhesion as an insulating resin layer.

The insulating resin layer is preferably formed of a polyimide layer (P1) having thermoplastic properties and a non-thermoplastic polyimide layer (P2) comprising a non-thermoplastic polyimide, and at least one of the non-thermoplastic polyimide layers (P2) has a polyimide layer (P1) which is a thermoplastic polyimide layer. That is, the polyimide layer (P1) is preferably provided on one side or both sides of the non-thermoplastic polyimide layer.

The non-thermoplastic polyimide layer forms a polyimide layer having low thermal expansion, and the thermoplastic polyimide layer forms a polyimide layer having high thermal expansion. Here, the polyimide layer having low thermal expansion means a polyimide layer having a coefficient of thermal expansion (coefficient of thermal expansion, CTE) of preferably 1ppm/K or more and 25ppm/K or less, more preferably 3ppm/K or more and 25ppm/K or less. The polyimide layer having high thermal expansion is preferably a polyimide layer having a CTE of 35ppm/K or more, more preferably 35ppm/K or more and 80ppm/K or less, and still more preferably 35ppm/K or more and 70ppm/K or less. The polyimide layer can be formed to have a desired CTE by appropriately changing the combination of raw materials used, the thickness, and the drying/hardening conditions.

The Coefficient of Thermal Expansion (CTE) of the entire insulating resin layer is preferably in the range of 10ppm/K to 30 ppm/K. By controlling such a range, deformation such as curling can be suppressed, and high dimensional stability can be ensured. Here, CTE is an average value of thermal expansion coefficients in the longitudinal (machine direction, MD) direction and the transverse (transverse direction, TD) direction of the insulating resin layer.

Here, the non-thermoplastic polyimide is generally a polyimide which does not exhibit softening and adhesion even when heated, but in the present invention, it means that the storage modulus of elasticity at 30 ℃ measured using a dynamic viscoelasticity measuring apparatus (dynamic mechanical analyzer (dynamic mechanical analyzer, DMA)) is 1.0x10 ⁹ The storage elastic coefficient at 350 ℃ and Pa or above is 1.0X10 ⁹ Polyimide of Pa or more. In addition, the thermoplastic polyimide (thermoplastic polyimide) (also referred to as "TPI") is generally a polyimide in which the glass transition temperature (Tg) can be clearly confirmed, but in the present embodiment, it means that the storage modulus of elasticity at 30 ℃ measured using DMA is 1.0×10 ⁹ The storage elastic modulus at 300 ℃ of Pa or more is less than 1.0X10 ⁸ Polyimide of Pa.

When the thickness of the polyimide layer (P1) in contact with the metal layer in the insulating resin layer is T1 and the thickness of the main polyimide layer is T2, the thickness of T1 is preferably in the range of 1 μm to 4 μm, and the thickness of T2 is preferably in the range of 4 μm to 30 μm. In other respects, the thickness of T1 is preferably 20% or less with respect to the thickness of the insulating resin layer. Here, "main" means that the thickness is the largest among the plurality of polyimide layers constituting the insulating resin layer, and it is preferable that the thickness is 60% or more, more preferably 70% or more, and still more preferably 80% or more with respect to the thickness of the insulating resin layer. The primary polyimide layer is preferably constructed of a non-thermoplastic polyimide.

In the case of the insulating resin layer including the polyimide layer, the 1% weight loss temperature (Td 1) in the thermal decomposition test is 450 ℃ or higher, preferably 470 ℃ or higher, and more preferably 490 ℃ or higher. By controlling such a range, the heat resistance is sufficient even when applied to a main structure of an FPC or the like.

In addition, the heat resistance (solder heat resistance) based on the solder heat resistance test in the insulating resin layer including the polyimide layer is preferably 190 ℃ or higher, more preferably 200 ℃ or higher. Solder heat resistance was evaluated by the method described in examples.

The insulating resin layer containing the polyimide layer preferably has heat resistance with a glass transition temperature (Tg) of 280 ℃ or higher. More preferably 350℃or higher, and still more preferably 380℃or higher.

The in-plane retardation of the insulating resin layer including the polyimide layer is preferably 1nm or more and 100nm or less. More preferably 1nm or more and less than 15nm.

(composition of polyimide layer)

The composition of the polyimide layer used in the insulating resin layer of the present invention is not particularly limited, and preferably has the following composition.

The polyimide layer contains a polyimide containing an acid anhydride residue and a diamine residue, and the polyimide constituting at least one polyimide layer (P1) contains 50 mol% or more of an acid anhydride residue derived from an aromatic tetracarboxylic acid anhydride represented by the general formula (1), preferably 70 mol% or more, more preferably 90 mol% or more, with respect to all acid anhydride residues derived from an acid anhydride component, and by setting the range to such a range, heat resistance and low retardation are easily exhibited. Further, the diamine residue derived from the aromatic diamine compound represented by the general formula (2) is contained in an amount of 50 mol% or more based on the total diamine residues contained in the polyimide. Preferably 70 mol% or more, more preferably 90 mol% or more.

The aromatic tetracarboxylic anhydride represented by the general formula (1) imparts flexibility to polyimide, and reduces pi-pi stacking interaction between polymer chains, etc., so that Charge Transfer (CT) between an aromatic tetracarboxylic acid residue and an aromatic diamine residue is less likely to occur, and thus it is considered that the obtained polyimide can be made nearly colorless and transparent. The aromatic diamine compound represented by the general formula (2) has two or more benzene rings, and has an amino group directly bonded to at least two benzene rings and a divalent linking group Z, and thus the degree of freedom of the polyimide molecular chain increases, and it is considered that the aromatic diamine compound contributes to improvement of flexibility of the polyimide molecular chain and promotion of high toughness. In the present invention, the acid anhydride residue means a tetravalent group derived from tetracarboxylic dianhydride, and the diamine residue means a divalent group derived from a diamine compound.

The acid anhydride residue contained in the polyimide constituting the polyimide layer (P1) directly laminated on the metal layer is preferably an acid anhydride residue derived from an aromatic tetracarboxylic acid anhydride represented by the general formula (1).

[ chemical 1]

In the formula (1), X represents a single bond, selected from-O-, or-C (CF) ₃ ) ₂ Divalent radicals in (E).

Examples of the aromatic tetracarboxylic anhydride represented by the formula (1) include: 4,4'-oxydiphthalic dianhydride (4, 4' -oxydiphthalic dianhydride, ODPA), 3', 4' -biphenyltetracarboxylic dianhydride (3, 3', 4' -biphenyl tetracarboxylic dianhydride, BPDA), 2-bis (3, 4-dicarboxyphenyl) -hexafluoropropane dianhydride (2, 2-bis (3, 4-dicarboxyphenyl) -hexafluoropropane dianhydride,6 FDA). These aromatic tetracarboxylic acid anhydrides are preferable because they can provide strength and flexibility to polyimide films, have excellent heat resistance and transparency, and can control CTE in an appropriate range. Among them, ODPA and 6FDA are particularly preferable.

The diamine residue contained in the polyimide constituting the polyimide layer (P1) is preferably a diamine residue derived from an aromatic diamine compound represented by the general formula (2).

[ chemical 2]

In the formula (2), Z independently represents a member selected from the group consisting of-O-, -S-, -CH ₂ -、-CH(CH ₃ )-、-C(CH ₃ ) ₂ -、-CO-、-COO-、-SO ₂ Divalent radicals in-NH-or-NHCO-, preferably-O-. n is n ₂ Represents an integer of 0 to 4, preferably 0 or 1.R is a substituent, and independently represents a halogen atom, or an alkyl group or an alkoxy group which may be substituted with a halogen atom having 1 to 6 carbon atoms, or a phenyl group or a phenoxy group which may be substituted with a monovalent hydrocarbon group or an alkoxy group having 1 to 6 carbon atoms. n is n ₁ Independently represents an integer of 0 to 3, preferably 0 or 1. Here, the term "independently" means that in the formula (2), a plurality of substituents R, a divalent group Z, and an integer n ₁ May be the same or different. In the formula (2), the hydrogen atoms in the terminal two amino groups may be substituted, and may be-NR ₃ R ₄ (here, R ₃ 、R ₄ Independently refers to any substituent such as an alkyl group). The same applies to other diamine compounds.

Wherein in the general formula (1), in the case where X is a single bond, Z in the formula (2) independently represents a member selected from the group consisting of-O-, -S-, -CH ₂ -、-CH(CH ₃ ) -or-NH-.

Examples of the aromatic diamine compound represented by the formula (2) include: 3,3 '-diaminodiphenyl methane, 3' -diaminodiphenyl propane, 3 '-diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfone, 3-diaminodiphenyl ether, 3,4 '-diaminodiphenyl methane, 3,4' -diaminodiphenyl propane, 3,4 '-diaminodiphenyl sulfide, 3,4' -diaminobenzophenone, (3, 3 '-diamino) diphenyl amine, 1, 4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene (1, 3-bis (3-aminophenoxy) benzene, APB), 1,3-bis (4-aminophenoxy) benzene (1, 3-bis (4-aminophenoxy) benzene, TPE-R), 3- [4- (4-aminophenoxy) phenoxy ] aniline, 3- [3- (4-aminophenoxy) phenoxy ] aniline, 4' - [ 2-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 4'- [ 4-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 4' - [ 5-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 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- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] benzophenone, bis [4,4'- (3-aminophenoxy) ] anilide, 4- [3- [4- (4-aminophenoxy) phenoxy ] aniline, 4' - [ oxybis (3, 1-phenylene oxy) ] diphenylamine, bis [4- (4-aminophenoxy) phenyl ] ether (bis [4- (4-aminophenoxy) phenyl ] ether, BAPE), bis [4- (4-aminophenoxy) phenyl ] ketone (bis [4- (4-aminophenoxy) phenyl ] ketne, BAPK), bis [4- (3-aminophenoxy) ] biphenyl, bis [4- (4-aminophenoxy) biphenyl, 2-bis (4-aminophenoxy) phenyl) propane (2, 2'-bis (4-aminophenoxy) propane, BAPP), 4' -diphenyl ether and the like. Of these, 1,3-bis (3-aminophenoxy) benzene (APB) and 1,3-bis (4-aminophenoxy) benzene (TPE-R) are preferable.

Other acid anhydride residues may be contained as long as the object of the present invention is not impaired. When other acid anhydride residues are contained, the content is 50 mol% or less, preferably less than 30 mol%, and more preferably less than 10 mol% of all acid anhydride residues.

Examples of the other acid anhydride residue include acid anhydride residues derived from: pyromellitic dianhydride, 3',4' -benzophenone tetracarboxylic dianhydride, 2', 3' -benzophenone tetracarboxylic dianhydride, 2, 3',4' -benzophenone tetracarboxylic dianhydride, naphthalene-1, 2,5, 6-tetracarboxylic dianhydride, naphthalene-1, 2,4, 5-tetracarboxylic dianhydride, naphthalene-1, 4,5, 8-tetracarboxylic dianhydride, naphthalene-1, 2,6, 7-tetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-2, 3,6, 7-tetracarboxylic dianhydride, 2, 6-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 2, 7-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 2,3,6, 7-tetrachloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 1,4,5, 8-tetrachloronaphthalene-2, 3,6, 7-tetracarboxylic dianhydride, 2 '; 3,3' -biphenyltetracarboxylic dianhydride, 2, 3',4' -biphenyltetracarboxylic dianhydride, 3",4, 4' -p-terphenyl tetracarboxylic dianhydride, 2', 3' -p-terphenyl tetracarboxylic dianhydride, 2, 3',4' -p-terphenyl tetracarboxylic dianhydride, 2-bis (2, 3-dicarboxyphenyl) -propane dianhydride, 2-bis (3, 4-dicarboxyphenyl) -propane dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) sulfone dianhydride, bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, perylene-2, 3,8, 9-tetracarboxylic dianhydride, perylene-3, 4,9, 10-tetracarboxylic dianhydride, perylene-4, 5,10, 11-tetracarboxylic dianhydride, perylene-5, 6,11, 12-tetracarboxylic dianhydride, phenanthrene-1, 2,7, 8-tetracarboxylic dianhydride, phenanthrene-1, 2,6, 7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-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 '-oxydiphthalic dianhydride, (trifluoromethyl) pyromellitic dianhydride, bis (heptafluoropropyl) pyromellitic dianhydride, pentafluoroethyl (3, 3' -dicarboxyphenyl) pyromellitic dianhydride, bis (3, 5 '-difluorophenyl) propane (3, 5' -bis (3, 5 '-dicarboxyphenyl) pyromellitic dianhydride 4,4' -tetracarboxylic biphenyl dianhydride, 2', 5' -tetra (trifluoromethyl) -3,3', 4' -tetracarboxylic biphenyl dianhydride, 5 '-bis (trifluoromethyl) -3,3',4,4 '-Tetracarboxydiphenyl ether dianhydride, 5' -bis (trifluoromethyl) -3,3',4,4' -Tetracarboxybenzophenone dianhydride, bis { (trifluoromethyl) dicarboxyphenoxy } benzene dianhydride, bis { (trifluoromethyl) dicarboxyphenoxy } trifluoromethyl benzene dianhydride, bis (dicarboxyphenoxy) trifluoromethylphenyl dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2-bis {4- (3, 4-dicarboxyphenoxy) phenyl } hexafluoropropane dianhydride, bis { (trifluoromethyl) dicarboxyphenoxy } biphenyl dianhydride, bis { (trifluoromethyl) dicarboxyphenoxy } diphenyl ether dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl dianhydride, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, fluorenylene diphthalic anhydride, 1,2,4, 5-cyclohexane tetracarboxylic dianhydride. Among these, anhydride residues derived from pyromellitic dianhydride or 3,3',4' -biphenyl tetracarboxylic dianhydride are preferable in terms of being able to provide strength and flexibility to the polyimide film and to control the Coefficient of Thermal Expansion (CTE) of the polyimide film to an appropriate range without excessively increasing.

Similarly, diamine residues derived from other diamine compounds may be contained as long as the object of the present invention is not hindered. When other diamine residues are contained, the content is 50 mol% or less, preferably less than 30 mol%, and more preferably less than 10 mol% of all diamine residues.

Examples of the other diamine residues include diamine residues derived from: 2,2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl (2, 2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, TFMB), bis [4- (4-aminophenoxy) phenyl ] sulfone (BAPS), 4, 6-dimethyl-m-phenylenediamine, 2, 5-dimethyl-p-phenylenediamine, 2, 4-diaminomesitylene, 3' -dimethyl-4, 4' -diaminodiphenylmethane, 3,5,3',5' -tetramethyl-4, 4' -diaminodiphenylmethane, 2, 4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4' -diaminodiphenylpropane, 3' -diaminodiphenylpropane 4,4' -diaminodiphenylethane, 3' -diaminodiphenylethane, 4' -diaminodiphenylmethane, 3' -diaminodiphenylmethane, 2-bis (4-aminophenoxyphenyl) propane 4,4' -diaminodiphenylethane, 3' -diaminodiphenylethane, 4' -diaminodiphenylmethane 3,3' -diaminodiphenylmethane, 2-bis (4-aminophenoxyphenyl) propane, 3,3 '-diaminobiphenyl, 3' -dimethyl-4, 4 '-diaminobiphenyl, 3' -dimethoxybenzidine, 4 '-diamino-p-terphenyl 3,3' -diamino-p-terphenyl, bis (p-aminocyclohexyl) methane, bis (p-beta-amino-tert-butylphenyl) ether bis (p-beta-methyl-delta-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 (beta-amino-t-butyl) toluene, 2, 4-diaminotoluene m-xylene-2, 5-diamine, p-xylene diamine, 2, 6-diaminopyridine, 2, 5-diamino-1, 3, 4-oxadiazole, piperazine, 4- (1H, 11H-twenty-fluoroundecyloxy) -1, 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-butoxy) -1, 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptyloxy) -1, 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-octyloxy) -1, 3-diaminobenzene, 4-pentafluorophenoxy-1, 3-diaminobenzene, 4- (2, 3,5, 6-tetrafluorophenoxy) -1, 3-diaminobenzene, 4- (4-fluorophenoxy) -1, 3-diaminobenzene, 4- (1H, 2H-perfluoro-1-hexyloxy) -1, 3-diaminobenzene, 4- (1H, 2H-perfluoro-1-dodecyloxy) -1, 3-diaminobenzene, (2, 5) -diaminobenzotrifluoride, diaminotetrakis (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene, 2, 5-diamino (perfluorohexyl) benzene, 2, 5-diamino (perfluorobutyl) benzene, 2'-bis (trifluoromethyl) -4,4' -diaminobiphenyl 3,3 '-bis (trifluoromethyl) -4,4' -diaminobiphenyl, octafluorobiphenyl, 4 '-diaminodiphenyl ether, 2-bis (4-aminophenyl) hexafluoropropane, 1, 3-bis (anilino) hexafluoropropane, 1, 4-bis (anilino) octafluorobutane, 1, 5-bis (anilino) decafluoropentane, 1, 7-bis (anilino) tetradecylfluoroheptane, 2' -bis (trifluoromethyl) -4,4 '-diaminodiphenyl ether, 3',5,5 '-tetra (trifluoromethyl) -4,4' -diaminodiphenyl ether, 3,3' -bis (trifluoromethyl) -4,4' -diaminobenzophenone, 4' -diamino-p-terphenyl, 1, 4-bis (p-aminophenyl) benzene, p-4-amino-2-trifluoromethylphenoxy) benzene, bis (aminophenoxy) bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 2-bis {4- (4-aminophenoxy) phenyl } hexafluoropropane, 2-bis {4- (3-aminophenoxy) phenyl } hexafluoropropane, 2-bis {4- (2-aminophenoxy) phenyl } hexafluoropropane 2, 2-bis {4- (4-aminophenoxy) -3, 5-dimethylphenyl } hexafluoropropane, 2-bis {4- (4-aminophenoxy) -3, 5-di-trifluoromethylphenyl } hexafluoropropane, 4' -bis (4-amino-2-trifluoromethylphenoxy) biphenyl 4,4' -bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 4' -bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4' -bis (3-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl } hexafluoropropane, bis { (trifluoromethyl) aminophenoxy } biphenyl, bis [ { (trifluoromethyl) aminophenoxy } phenyl ] hexafluoropropane, bis {2- [ (aminophenoxy) phenyl ] hexafluoroisopropyl } benzene, 4' -bis (4-aminophenoxy) octafluorobiphenyl. Among these, from the viewpoint of producing polyimide having high transparency and low coloring, preferably from 2, 2-bis- [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 9-bis [4- (3-aminophenoxy) phenyl ] fluorene, 2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, 4' -bis (2- (trifluoromethyl) -4-aminophenoxy) biphenyl diamine residues derived from diamine compounds such as 2, 2-bis (4- (2- (trifluoromethyl) -4-aminophenoxy) phenyl) hexafluoropropane, 4' -bis (3- (trifluoromethyl) -4-aminophenoxy) biphenyl, 4' -bis (3- (trifluoromethyl) -4-aminophenoxy) biphenyl, and p-bis (2-trifluoromethyl) -4-aminophenoxy benzene.

The toughness, thermal expansion, adhesion, glass transition temperature (Tg), and the like can be controlled by selecting the types of the acid anhydride residues and diamine residues, or the molar ratio of each of two or more acid anhydride residues or diamine residues.

In the resin film of the present invention, the main polyimide layer preferably contains a diamine residue derived from an aromatic diamine compound containing a fluorine atom and/or an acid anhydride residue derived from an aromatic tetracarboxylic acid anhydride containing a fluorine atom, in particular, in order to set the total light transmittance within a predetermined range.

The predominant polyimide preferably contains a fluorine-containing diamine residue. Since the fluorine-containing diamine residue has a bulky group containing a fluorine atom, it is considered that the polyimide is nearly colorless and transparent because the interaction such as pi-pi stacking between polymer chains is reduced and Charge Transfer (CT) between the aromatic tetracarboxylic acid residue and the aromatic diamine residue does not easily occur.

Examples of the fluorine-containing diamine residue include diamine residues derived from: diamine compounds such as 4,4 '-diamino-2, 2' -bis (trifluoromethyl) biphenyl (TFMB), 1, 4-bis (4-amino-2-trifluoromethylphenoxy) benzene, 3, 4-diamino-2, 2 '-bis (trifluoromethyl) biphenyl, 4' -bis (2- (trifluoromethyl) -4-aminophenoxy) biphenyl, 2-bis (4- (2- (trifluoromethyl) -4-aminophenoxy) phenyl) hexafluoropropane, 4 '-bis (3- (trifluoromethyl) -4-aminophenoxy) biphenyl, 4' -bis (3- (trifluoromethyl) -4-aminophenoxy) biphenyl, p-bis (2-trifluoromethyl) -4-aminophenoxy benzene, 2-bis- [4- (3-aminophenoxy) phenyl ] hexafluoropropane.

The fluorine-containing diamine residue preferably contains a diamine residue derived from a diamine compound represented by the following general formula (A1) (hereinafter, may be referred to as "A1 residue").

[ chemical 3]

In the general formula (A1), the substituent X independently represents an alkyl group having 1 to 3 carbon atoms substituted with a fluorine atom, and m and n independently represent integers of 1 to 4.

The A1 residue is an aromatic diamine residue, and has a biphenyl skeleton in which two benzene rings are linked by a single bond, so that an ordered structure is easily formed, and the orientation of the molecular chain in the in-plane direction is promoted, and therefore, increase in CTE of the main polyimide layer can be suppressed, and dimensional stability can be improved. From this viewpoint, the main polyimide layer preferably contains 50 parts by mole or more of A1 residues, more preferably contains A1 residues in a range of 50 parts by mole or more and 100 parts by mole or less, relative to 100 parts by mole of the total of all diamine residues.

Preferable specific examples of the A1 residue include diamine residues derived from diamine compounds such as 4,4' -diamino-2, 2' -bis (trifluoromethyl) biphenyl (TFMB) and 3, 4-diamino-2, 2' -bis (trifluoromethyl) biphenyl.

The main polyimide layer may contain a diamine residue derived from a diamine component generally used for the synthesis of polyimide as a diamine residue other than the above.

The primary polyimide layer preferably contains a fluorine-containing anhydride residue. The fluorine-containing acid anhydride residue has a bulky group containing a fluorine atom, and therefore, it is considered that the polyimide is nearly colorless and transparent because it reduces pi-pi stacking interaction between polymer chains and the like, and makes Charge Transfer (CT) between an aromatic tetracarboxylic acid residue and an aromatic diamine residue less likely to occur.

Examples of the fluorine-containing acid anhydride residue include acid anhydride residues derived from acid anhydride components such as 2,2' -bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6 FDA).

In order to control the CTE within the above range, the polyimide layer preferably contains a tetravalent anhydride residue derived from pyromellitic dianhydride (pyromellitic dianhydride, PMDA) represented by the following formula (B1) (hereinafter, sometimes referred to as "PMDA residue"). The PMDA residue is preferably contained in an amount of 50 parts by mole or more, more preferably 60 parts by mole or more and 100 parts by mole or less, based on 100 parts by mole of the total of all anhydride residues. When the PMDA residue is less than 50 parts by mole, the CTE of the polyimide layer (a) may be high and the dimensional stability may be lowered.

[ chemical 4]

In addition, the main polyimide layer may contain an acid anhydride residue derived from an acid anhydride component generally used for the synthesis of polyimide as an acid anhydride residue other than the above. As such an acid anhydride residue, an aromatic tetracarboxylic acid residue is preferable. In addition, alicyclic tetracarboxylic acid residues may be contained, and for example, acid anhydride residues derived from alicyclic tetracarboxylic acid dianhydride such as 1,2,3, 4-cyclobutane tetracarboxylic acid dianhydride, fluorenylene diphthalic acid anhydride, 1,2,4, 5-cyclohexane tetracarboxylic acid dianhydride, cyclopentanone bisspiro-norbornane tetracarboxylic acid dianhydride, and the like are preferable.

In the case of using the third polyimide layer P3, there is no particular limitation with respect to the P3, and a layer having the same composition as that of the polyimide layer P1 may be applied. When a composition different from that of the polyimide layer P1 is used, it is preferable that the diamine residue derived from the aromatic diamine compound represented by the general formula (A3) is contained in an amount of 50 mol% or more.

[ chemical 5]

In the formula (A3), Z independently represents a member selected from the group consisting of-O-, -S-, -CH ₂ -、-CH(CH ₃ )-、-C(CH ₃ ) ₂ -, or-SO ₂ Divalent radicals in (E), preferably-O-. n is n ₂ Represents an integer of 0 to 4, preferably 0 or 1.R is a substituent, independently a halogen atom, or an alkyl group or an alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a phenyl group or a phenoxy group which may be substituted with a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group. n is n ₁ Independently represents an integer of 0 to 3, preferably 0 or 1.

The aromatic diamine compound represented by the formula (A3) has two or more benzene rings, and has an amino group directly bonded to at least two benzene rings and a divalent linking group Z, whereby the degree of freedom of the polyimide molecular chain increases, and the aromatic diamine compound has high flexibility, which is thought to contribute to the improvement of flexibility of the polyimide molecular chain and promotes adhesion and high toughness.

In the case where a composition different from that of the polyimide layer P1 is applied to the polyimide layer P3, it is preferable that: the aromatic tetracarboxylic anhydride compound represented by the general formula (A3) contains 50 mol% or more of an acid anhydride residue derived from the aromatic tetracarboxylic anhydride represented by the general formula (1) relative to all acid anhydride residues, and 50 mol% or more of a diamine residue derived from the aromatic diamine compound represented by the general formula (A3) relative to all diamine residues contained in the polyimide.

Examples of the aromatic diamine compound represented by the formula (A3) include: 3,3 '-diaminodiphenyl methane, 3' -diaminodiphenyl propane, 3 '-diaminodiphenyl sulfide, 3' -diaminodiphenyl sulfone, 3-diaminodiphenyl ether, 3,4 '-diaminodiphenyl methane, 3,4' -diaminodiphenyl propane, 3,4 '-diaminodiphenyl sulfide, 3,4' -diaminobenzophenone, (3, 3 '-diamino) diphenyl amine, 1, 4-bis (3-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene (APB), 1, 3-bis (4-aminophenoxy) benzene (TPE-R) 3- [4- (4-aminophenoxy) phenoxy ] aniline, 3- [3- (4-aminophenoxy) phenoxy ] aniline, 4' - [ 2-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 4'- [ 4-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 4' - [ 5-methyl- (1, 3-phenylene) dioxy ] diphenylamine, 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) ] anilide, 4- [3- [4- (4-aminophenoxy) phenoxy ] aniline, 4' - [ oxybis (3, 1-phenylepoxy) ] diphenylamine, bis [4- (4-aminophenoxy) phenyl ] ether (BAPE), bis [4- (4-aminophenoxy) phenyl ] ketone (BAPK), bis [4- (3-aminophenoxy) ] biphenyl, bis [4- (4-aminophenoxy) ] biphenyl, 2-bis (4-aminophenoxyphenyl) propane (BAPP), 4' -diaminodiphenyl ether, and the like. Of these, 1, 3-bis (3-aminophenoxy) benzene (APB) and 1, 3-bis (4-aminophenoxy) benzene (TPE-R) are preferable.

Examples of the other diamine residues include diamine residues derived from: 2,2 '-bis (trifluoromethyl) -4,4' -diaminobiphenyl (TFMB), bis [4- (4-aminophenoxy) phenyl ] sulfone (BAPS), 4, 6-dimethyl-m-phenylenediamine, 2, 5-dimethyl-p-phenylenediamine, 2, 4-diaminomesitylene, 3 '-dimethyl-4, 4' -diaminodiphenylmethane, 3,5,3',5' -tetramethyl-4, 4 '-diaminodiphenylmethane, 2, 4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4' -diaminodiphenylpropane, 3 '-diaminodiphenylpropane, 4' -diaminodiphenylethane 3,3 '-diaminodiphenylethane, 4' -diaminodiphenylmethane, 3 '-diaminodiphenylmethane, 2-bis (4-aminophenoxyphenyl) propane, 2-bis [4- (4-aminophenoxy) phenyl ] propane 3,3' -diaminodiphenylethane, 4 '-diaminodiphenylmethane, 3' -diaminodiphenylmethane 2, 2-bis (4-aminophenoxyphenyl) propane, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 4,4 '-diamino-p-terphenyl, 3' -diamino-p-terphenyl, bis (p-aminocyclohexyl) methane, bis (p-beta-amino-t-butylphenyl) ether, bis (p-beta-methyl-delta-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 (beta-amino-t-butyl) toluene, 2, 4-diaminotoluene, m-xylene-2, 5-diamine, p-xylene-2, 5-diamine, m-xylene diamine, p-xylene diamine 2, 6-diaminopyridine, 2, 5-diamino-1, 3, 4-oxadiazole, piperazine, 4- (1H, 11H-twenty-fluoroundecyloxy) -1, 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-butoxy) -1, 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptyloxy) -1, 3-diaminobenzene, 4- (1H, 1H-perfluoro-1-octyloxy) -1, 3-diaminobenzene, 4-pentafluorophenoxy-1, 3-diaminobenzene, 4- (2, 3,5, 6-tetrafluorophenoxy) -1, 3-diaminobenzene, 4- (4-fluorophenoxy) -1, 3-diaminobenzene, 4- (1H, 2H-perfluoro-1-hexyloxy) -1, 3-diaminobenzene, 4- (1H, 2H-perfluoro-1-dodecyloxy) -1, 3-diaminobenzene, (2, 5) -diaminobenzotrifluoride, diaminotetrakis (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene, 2, 5-diamino (perfluorohexyl) benzene, 2, 5-diamino (perfluorobutyl) benzene, 2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, 3' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, and octafluorobiphenyl amine, 4' -diaminodiphenyl ether, 2-bis (4-aminophenyl) hexafluoropropane, 1, 3-bis (anilino) hexafluoropropane, 1, 4-bis (anilino) octafluorobutane, 1, 5-bis (anilino) decafluoropentane, 1, 7-bis (anilino) tetradecylfluoroheptane, 2' -bis (trifluoromethyl) -4,4' -diaminodiphenyl ether, 3',5,5' -tetra (trifluoromethyl) -4,4' -diaminodiphenyl ether, 3' -bis (trifluoromethyl) -4,4' -diaminobenzophenone, 4' -diamino-p-terphenyl, 1, 4-bis (p-aminophenyl) benzene, p- (4-amino-2-trifluoromethylphenoxy) benzene, bis (aminophenoxy) bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 2-bis {4- (4-aminophenoxy) phenyl } hexafluoropropane, 2-bis {4- (3-aminophenoxy) phenyl } hexafluoropropane, 2-bis {4- (2-aminophenoxy) phenyl } hexafluoropropane 2, 2-bis {4- (4-aminophenoxy) -3, 5-dimethylphenyl } hexafluoropropane, 2-bis {4- (4-aminophenoxy) -3, 5-di-trifluoromethylphenyl } hexafluoropropane, 4' -bis (4-amino-2-trifluoromethylphenoxy) biphenyl 4,4' -bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 4' -bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4' -bis (3-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl } hexafluoropropane, bis { (trifluoromethyl) aminophenoxy } biphenyl, bis { (trifluoromethyl) aminophenoxy } phenyl ] hexafluoropropane, bis {2- [ (aminophenoxy) phenyl ] hexafluoroisopropyl } benzene, 4' -bis (4-aminophenoxy) octafluorobiphenyl, in view of producing polyimide having high transparency and low coloring, preferably from 2, 2-bis- [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 9-bis [4- (3-aminophenoxy) phenyl ] fluorene, 2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, 4' -bis (2- (trifluoromethyl) -4-aminophenoxy) biphenyl diamine residues derived from diamine compounds such as 2, 2-bis (4- (2- (trifluoromethyl) -4-aminophenoxy) phenyl) hexafluoropropane, 4' -bis (3- (trifluoromethyl) -4-aminophenoxy) biphenyl, 4' -bis (3- (trifluoromethyl) -4-aminophenoxy) biphenyl, and p-bis (2-trifluoromethyl) -4-aminophenoxy benzene.

Next, a method for synthesizing polyimide constituting a plurality of polyimide layers will be described.

The polyimide of the present embodiment can be produced by reacting the acid anhydride and the diamine in a solvent to produce a polyamic acid, and then heating the resultant product to ring-close the resultant product. For example, the acid anhydride component and the diamine component are dissolved in an organic solvent in approximately equimolar amounts, and the polymerization reaction is carried out by stirring at a temperature in the range of 0 ℃ to 100 ℃ for 30 minutes to 24 hours, whereby a polyamic acid as a precursor of polyimide is obtained. In the reaction, the reaction components are dissolved so that the precursor to be produced is in the range of 5 to 30 wt%, preferably 10 to 20 wt%, in the organic solvent. Examples of the organic solvent used in the polymerization reaction include: n, N-dimethylformamide, N-dimethylacetamide (N, N-dimethyl acetamide, DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), gamma-butyrolactone, and the like. These solvents may be used in combination of two or more kinds, and further, aromatic hydrocarbons such as xylene and toluene may be used in combination. The amount of the organic solvent used is not particularly limited, and is preferably adjusted so that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction becomes about 5 to 30% by weight.

In the synthesis of polyimide, only one of the acid anhydride and the diamine may be used, or two or more of them may be used in combination. The thermal expansion, adhesion, glass transition temperature, and the like can be controlled by selecting the types of the acid anhydride and the diamine, or by using the molar ratio of two or more acid anhydrides or diamines.

The polyimide of the present embodiment may also use a capping agent. As the blocking agent, monoamines or dicarboxylic acids are preferable. The amount of the blocking agent to be introduced is preferably in the range of 0.0001 to 0.1 mol, particularly preferably in the range of 0.001 to 0.05 mol, based on 1 mol of the acid anhydride component. As monoamine type blocking agents, for example, it is recommended that: methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, aniline, 4-methylaniline, and the like. Among these, benzylamine and aniline can be suitably used. The dicarboxylic acid-based capping agent is preferably a dicarboxylic acid, and a part of the dicarboxylic acid-based capping agent may be closed. For example, it may be recommended that: phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, cyclopentane-1, 2-dicarboxylic acid, 4-cyclohexene-1, 2-dicarboxylic acid, and the like. Among these, phthalic acid and phthalic anhydride can be suitably used.

The polyamic acid synthesized is generally advantageously used as a reaction solvent solution, but may be concentrated, diluted, or replaced with other organic solvents as desired. In addition, polyamide acid generally has excellent solvent solubility, so can be advantageously used. 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 in the range of 80 ℃ to 400 ℃ for 1 hour to 24 hours can be suitably used.

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

Method for producing metal-clad laminate

As described above, the metal-clad laminate of the present invention is suitable for forming an insulating resin layer including a plurality of polyimide layers, in particular, by a casting method or a sequential coating method on a metal layer as a support base, from the viewpoint of dimensional stability and the like, but is not particularly limited. For example, it can also be prepared by: an insulating resin layer (resin film) comprising the polyimide of the present invention is prepared, and a metal layer is formed by sputtering a metal thereon to form a seed layer, and then plating, for example.

In addition, it can be prepared by the following method: an insulating resin layer (resin film) comprising the polyimide of the present invention is prepared, and a metal foil is laminated thereon by a method such as thermocompression bonding.

In these cases, in order to improve the adhesion between the resin film and the metal layer, the surface of the resin film may be subjected to a modifying treatment such as a plasma treatment.

In the case of manufacturing a metal-clad laminate having metal layers on both sides, it can be obtained, for example, by: the polyimide layer of the single-sided metal-clad laminate obtained by the above method is directly or optionally provided with an adhesive layer that does not inhibit the transparency of the insulating resin layer, and then the metal layer is laminated by a method such as thermocompression bonding. The hot pressing temperature at the time of the thermocompression bonding of the metal layer is not particularly limitedIt is desirable that the polyimide layer adjacent to the metal layer used has a glass transition temperature or higher. In addition, regarding the hot pressing pressure, it is desirable to be 1kg/m, although it also depends on the kind of pressing equipment used ² ～500kg/m ² Is not limited in terms of the range of (a).

< tear Strength >

In the metal-clad laminate of the present invention, the 180 ° peel strength between the insulating resin layer and the metal layer is preferably 0.3kN/m or more, more preferably 0.5kN/m or more.

In the present specification, the evaluation of physical properties and characteristic values is performed under the conditions described in examples, and the measurement values at room temperature (23 ℃) are not particularly described.

< usage >

The metal-clad laminate of the present invention is useful as a circuit board material such as a conventional FPC or a member such as a mask used in the process of manufacturing electronic parts. In addition, the transparent FPC obtained by forming wiring by circuit processing the metal-clad laminate of the present invention is, as described above, a "transparent antenna" which is used as a transparent antenna and is formed on the surface of a window glass to base the window, or a substrate for a transparent heater or a transparent display or a transparent touch panel, particularly a large-sized electro-optical panel or an LED transparent display including LED vision, which is used for embedding an antenna in a display in a mobile application, or is effectively used as a transparent heater or a transparent display or a transparent touch panel embedded in an automobile glass.

< Circuit Board >)

The metal-clad laminate of the present invention is mainly useful as a circuit board such as an FPC. The circuit board can be manufactured by processing the metal layer of the metal-clad laminate of the present invention into a pattern by a conventional method and forming a wiring layer. Patterning may be performed by any method using photolithography, etching, or the like, for example. In addition, in manufacturing a circuit board, as a process that is generally performed, for example, a process of processing a through hole in a preceding process, or a process of terminal plating, outline processing, or the like in a subsequent process may be performed according to a conventional method.

Examples (example)

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the scope of these examples. In the following examples, unless otherwise specified, various measurements and evaluations were based on the following.

[ calculation of light transmittance and YI (yellowness) ]

The light transmittance and (YI) of the resin film (also referred to as insulating resin layer; hereinafter the same) were measured by a UV-3600 spectrophotometer manufactured by Shimadzu corporation (50 mm. Times.50 mm).

1) Transmittance of light

The light transmittance (T400, T430 and T450) of each of the light having wavelengths of 400nm, 430nm and 450nm was calculated in accordance with JIS Z8722.

2)YI

According to JIS Z8722, the calculation is performed based on the calculation formula represented by the following formula (1).

YI＝100×(1.2879X-1.0592Z)/Y···(1)

X, Y and Z: tristimulus value of test piece

YI of a resin film having a thickness of 25 μm _(T25) The value of YI calculated by the above formula (1) is substituted into the following formula (2).

YI _(T25) ＝YI/T×25···(2)

T: thickness of resin film (μm)

[ evaluation of reflectance and hue ]

Each of the single-sided metal-clad laminates of examples and comparative examples, and each of the copper foils used in the production thereof, were attached to a glass plate (12.5 cm square) so that the mirror surface side of the copper foil was in contact with the glass plate. The resin surface side or the copper foil coated surface side of the substrate was irradiated with light using UH-4100 manufactured by Hitachi High-technologies, inc., and the light was measured in a wavelength range: reflectance and hue (L, a, b) at 380nm to 780 nm. The light source used was a C light source (2 ° field of view). The reflectance at 680nm was used as a result of the reflectance.

[ in-plane retardation; re ]

The polyimide films (50 mm. Times.50 mm) obtained in examples and comparative examples were subjected to a birefringence-retardation evaluation apparatus (WPA-100 manufactured by Photonic Lattice) and a rotation apparatus for rotating the sample so as to change the incident angle of light incident on the sample was attached thereto, and the dependence of retardation on the incident angle of the polyimide film was measured at a wavelength of 543 nm. For the measured value, the measured data of the angle of incidence dependence of the retardation is numerically analyzed to determine the retardation Re in the plane direction.

[ measurement of Coefficient of Thermal Expansion (CTE) ]

The thermal expansion coefficient of the resin film (3 mm. Times.15 mm) was measured from the elongation (linear expansion) of the resin film at the time of cooling down by heating up from 30℃to 280℃at a heating rate of 10℃per minute while applying a load of 5.0g by a Thermal Mechanical Analysis (TMA) apparatus, and then cooling down from 250℃to 100 ℃.

[ calculation of total light transmittance (T.T.) and haze (turbidity) ]

The total light transmittance (T.T.) and HAZE (turbidity) of the resin film (50 mm. Times.50 mm) were measured by a HAZE METER (HAZE METER) NDH500 manufactured by Nippon electric color industry Co., ltd.) according to JIS K7136.

[ measurement of viscosity ]

The viscosity was measured by using a conical plate viscometer (manufactured by tokyo counter (Tokimec)) equipped with a constant temperature water tank, and the polyamic acid solution obtained in the synthesis example was measured at 25 ℃.

[ measurement of glass transition temperature (Tg) ]

The glass transition temperature (Tan. Delta. Maximum:. Degree.C.) of the resin film (10 mm. Times.22.6 mm) was determined by measuring the dynamic viscoelasticity at 5℃per minute at a temperature rise from 20℃to 400℃by a dynamic thermo-mechanical analyzer.

[ measurement of thermal decomposition temperature (Td 1) ]

A resin film having a weight of 10mg to 20mg was heated from 30℃to 550℃at a constant rate by a thermogravimetric analysis (TG) device TG/DTA6200 manufactured by SeikO corporation under a nitrogen atmosphere, the weight change at this time was measured, the weight at 200℃was set to zero, and the temperature at which the weight reduction rate was 1% was set to the thermal decomposition temperature (Td 1).

[ measurement of tear Strength ]

The resin side of the test specimen having a circuit with a width of 1mm obtained from the laminate was fixed to an aluminum plate using a tensile tester, and copper was peeled off at a speed of 50mm/min in a direction of 180 ° to obtain the peel strength.

[ measurement of surface roughness of copper foil ]

The sample was cut into a square size of about 10mm, fixed on a sample stage using a double-sided tape, irradiated with soft X-rays, and after removing static electricity on the copper foil surface, the surface roughness was measured. The arithmetic average roughness Ra and the maximum height Rz of the copper foil surface were measured under the following measurement conditions using a scanning probe microscope (atomic force microscope (atomic force microscope, AFM), manufactured by Bruker (Bruker) AXS company, trade name: dimension Icon (SPM)) and a scanning probe microscope (scanning probe microscope, SPM). The measurement conditions are as follows.

Measurement mode: tapping mode (tapping mode)

Measurement area: 1 μm by 1 μm

Scanning speed: 1Hz

And (3) probe: AC160 manufactured by Olympus (Olympus)

Analysis software: nano-mirror analysis (NanoScope Analysis)

[ measurement of surface roughness of film ]

The film surface in contact with the copper foil was measured. The film sample was cut into a square size of about 10mm, fixed to a sample stage with a double-sided tape, irradiated with soft X-rays, and after removing static electricity on the surface, the surface roughness was measured. The arithmetic average roughness Ra and Rz of the surface were measured under the following measurement conditions using a scanning probe microscope (AFM, manufactured by Bruker) AXS company, trade name: size Icon (Dimension Icon) type SPM). The measurement conditions are as follows.

Measurement mode: tapping mode

Measurement area: 1 μm by 1 μm

Scanning speed: 1Hz

And (3) probe: AC160 manufactured by Olympus (Olympus)

Analysis software: nano-mirror analysis (NanoScope Analysis)

[ measurement of solder Heat resistance ]

Commercially available photoresist films were laminated on the metal layer side of each of the single-sided copper-clad laminated plates obtained in examples and comparative examples (except for example 11 and example 12), and exposure was performed using a predetermined mask for patterning (365 nm, exposure amount 500J/m) ² Left or right), the resist layer is cured in a circular pattern having diameters of 20mm, 15mm, 10mm, 5mm, 3mm, 1mm, and 0.5mm on the metal layer side.

Next, the hardened resist portion was developed (the developer was 1% naoh aqueous solution), the metal layer unnecessary for forming the predetermined pattern was removed by etching using an aqueous chloride aqueous solution, and the hardened resist layer was removed by alkali peeling, whereby a patterned sample (a laminate having a circular pattern with a diameter of 1mm formed on the metal layer side of the single-sided metal-clad laminate) for evaluating the heat resistance corresponding to the lead-free solder was obtained.

The samples were immersed in molten solder baths having different temperatures for 10sec, and the presence or absence of deformation and expansion in the copper foil layer portions was observed. The highest temperature of the solder bath, which does not deform or expand or peel off at the copper foil layer portion, was taken as the solder heat-resistant temperature.

The abbreviations used in the examples and the like refer to the following compounds.

APB:1, 3-bis (3-aminophenoxy) benzene

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

TFMB:2,2 '-bis (trifluoromethyl) -4,4' -diaminobiphenyl

BAPS: bis [4- (4-aminophenoxy) phenyl ] sulfone

AAPBI: 5-amino-2- (4-aminophenyl) benzimidazoles

PMDA: pyromellitic dianhydride

6FDA:2, 2-bis (3, 4-dicarboxyphenyl) -hexafluoropropane dianhydride

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

ODPA:4,4' -oxydiphthalic dianhydride

CBDA:1,2,3, 4-cyclobutane tetracarboxylic dianhydride

DMAc: n, N-dimethylacetamide

m-TB:4,4 '-diamino-2, 2' -dimethylbiphenyl

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

Synthesis example 1

To synthesize the polyamic acid solution a, DMAc as a solvent was added to a 200ml separable flask so as to have a solid content shown in table 1 under a nitrogen flow, and the diamine component and the acid anhydride component shown in table 1 were added and dissolved while stirring at room temperature. Thereafter, the solution was continuously stirred at room temperature for 6 hours to perform polymerization reaction, thereby preparing a viscous solution a of polyamic acid. The viscosity was 3000cP.

Synthesis example 2

To synthesize the polyamic acid solution B, DMAc as a solvent was added to a 200ml separable flask so as to have a solid content shown in table 1 under a nitrogen flow, and the diamine component and the acid anhydride component shown in table 1 were heated and dissolved at 45 ℃ for 2 hours while stirring. Thereafter, the solution was continuously stirred at room temperature for 2 days to perform polymerization reaction, thereby preparing a viscous solution B of polyamic acid. The viscosity was 27000cP.

Synthesis example 3, synthesis example 5 to Synthesis example 8

The polyamic acid solution C and the polyamic acid solutions E to H were polymerized by the same method as in synthesis example 1, with the monomer types changed as shown in table 1. A viscous solution C of polyamic acid, a viscous solution E of polyamic acid to a viscous solution H of polyamic acid are prepared. The viscosity is shown in Table 1.

Synthesis example 4

The polyamic acid solution D was polymerized by the same method as in synthesis example 2, with the monomer types changed as shown in table 1. A viscous solution D of polyamic acid was prepared. The viscosity is shown in Table 1.

TABLE 1

Table 2 shows the types of copper foil used as the metal layer in the present invention.

TABLE 2

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Example 1

The solution of the polyamic acid solution A was uniformly applied to copper foil I (electrolytic copper foil, trade name: TQ-M4-VSP, thickness: 12 μm) so that the thickness after hardening became 2 μm, and then subjected to stage heat drying at a temperature ranging to 120℃to remove the solvent. Next, the solution of the polyamic acid solution B was uniformly applied thereon so that the thickness after curing became 25 μm, and then subjected to stage heat drying in a temperature range up to 120 ℃ and the solvent was removed. Further, the solution of the polyamic acid solution C was uniformly applied thereto so that the thickness after curing became 2. Mu.m, and then subjected to stage heat drying at a temperature ranging from 120℃to remove the solvent. Thus, three polyamic acid layers were formed, and then subjected to stepwise heat treatment from 125℃to 360℃to complete imidization, thereby forming an insulating resin layer having a thickness of 29 μm including a polyimide layer A/polyimide layer B/polyimide layer C, and a metal-clad laminate 1A (in the table, referred to as a "metal laminate") was produced.

The obtained single-sided metal clad laminate 1A was etched to remove copper foil using an aqueous solution of ferric chloride, thereby preparing a polyimide film 1A. The haze, t.t., T400, T430, T450, YI were determined for the polyimide film 1a _(T25) CTE, td1, and Re. The measurement results are shown in Table 3. Here, YI _(T25) The thickness of the polyimide film was converted into 25 μm and the yellowness was shown.

The obtained single-sided metal-clad laminate 1A was measured for reflectance and hue (L, a, b) from the resin film side. In addition, the peel strength of the polyamic acid coated surface was 0.56kN/m. In addition, the solder heat resistance was 360 ℃.

Examples 2 to 10

Except that the copper foil and the polyamic acid solution shown in tables 3 to 5 were usedExcept for this, a single-sided metal-clad laminate 2A to a single-sided metal-clad laminate 10A were produced in the same manner as in example 1, and polyimide films 2A to 10A were produced. Haze, t.t., T400, T430, T450, YI were determined for the polyimide films 2a to 10a _(T25) CTE, td1, and Re. The reflectance, hue, peel strength, and solder heat resistance were obtained for each of the single-sided metal-clad laminate 2A to the single-sided metal-clad laminate 10A.

Example 11

Copper foil I (electrolytic copper foil, trade name; TQ-M4-VSP-12, thickness; 12 μm) was cut into two sheets 15 cm. Times.15 cm, and EA-2000 (thickness; 25 μm) manufactured by AGC was sandwiched as a PFA resin film therebetween in a state where the coated surfaces were faced each other, and was thermally pressed at 320℃for 5min by a press machine to prepare a metal clad laminate. Only the copper foil on one side of the produced double-sided metal-clad laminate was etched away using an aqueous solution of ferric chloride, thereby obtaining a single-sided metal-clad laminate 11A. The PFA resin was directly evaluated for the same items (except Re) as in the above examples. The single-sided metal-clad laminate 11A was also evaluated in the same manner as in the above example. The evaluation results are shown in table 6.

Example 12

A single-sided metal-clad laminate 12A was obtained and evaluated in the same manner as in example 11 except that the copper foil on one side was changed to copper foil III. The evaluation results are shown in table 6.

Comparative examples 1 to 5

Polyimide films 13A to 16A were produced in the same manner as in example 1 except that the copper foil and the polyamic acid solution shown in table 7 were used to produce the single-sided metal-clad laminate 13A to the single-sided metal-clad laminate 16A. Further, a single-sided metal-clad laminate 17A was obtained in the same manner as in example 11. The polyimide films 13A to 17A and the single-sided metal-clad laminates 13A to 17A were evaluated in the same manner as in the above examples. The measurement results are shown in Table 7.

TABLE 3

TABLE 4

TABLE 5

TABLE 6

TABLE 7

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Claims

1. A metal-clad laminate having a metal layer on one or both surfaces of an insulating resin layer, characterized in that,

2. The metal clad laminate of claim 1, wherein L x a b x the color system in the metal layer is 60 or less and a is 15 or less.

3. The metal-clad laminate according to claim 1, wherein when a surface of the metal layer in contact with the insulating resin layer is measured through the insulating resin layer, a reflectance at 680nm is 50% or less.

4. The metal-clad laminate according to claim 1, wherein the insulating resin layer has a total light transmittance of 75% or more.

5. The metal-clad laminate according to claim 1, wherein the insulating resin layer has a haze of 10% or less.

6. The metal-clad laminate according to claim 1, wherein the insulating resin layer has a 1% weight reduction temperature of 450 ℃ or higher.

7. The metal-clad laminate according to claim 1, wherein the solder heat resistance is 200 ℃ or higher.

8. The metal-clad laminate according to claim 1, wherein the insulating resin layer has a 180 ° peel strength from the metal layer of 0.3kN/m or more.

9. The metal-clad laminate according to claim 1, wherein the thickness of the metal layer is in a range of 1 μm or more and 25 μm or less.

10. A circuit board obtained by wiring the metal layer of the metal-clad laminate according to any one of claims 1 to 9.