JP6936639B2 - Laminates, flexible metal-clad laminates, and flexible printed circuit boards - Google Patents

Description

The present invention relates to a laminate that can be suitably used for a high-frequency circuit board, a flexible metal-clad laminate having metal foils on one or both sides thereof, and a flexible printed circuit board.

In recent years, for the purpose of improving the information processing capability of electronic devices, the frequency of electric signals transmitted through circuits has been increased. With the increase in the frequency of the electric signal, it is desired for the circuit board to maintain the electric reliability, suppress the decrease in the transmission speed of the electric signal in the circuit, and suppress the loss of the electric signal. A material having a low relative permittivity and a dielectric loss tangent is required in the region of 10 GHz).

The flexible metal-clad laminate (hereinafter, also referred to as FCCL) used for manufacturing a circuit board is obtained by providing a metal foil on one side or both sides of a base resin film. As a method for producing a flexible metal-clad laminate, a metal foil is cast or coated with a solution of polyamic acid, which is a precursor of polyimide, and then imidized. Examples thereof include a metallizing method in which a layer is provided, and a thermal lamination method in which a polyimide film and a metal foil are bonded together via an adhesive layer such as a thermoplastic polyimide. Among these, the thermal lamine method is superior to other methods in that the thickness range of the metal foil that can be supported is wider than that of the Cass method and the equipment cost is lower than that of the metallizing method.

In recent years, with the adoption of lead-free solder, the required level of moisture-absorbing solder resistance has become higher than before, and in order to cope with this, the Tg (glass transition temperature) of the film in contact with the metal foil is increasing. As a result, the temperature required for thermal lamination is also inevitably high. Therefore, the thermal stress applied to the material such as the base resin film and the adhesive layer becomes large, and the dimensional change is likely to occur.

By the way, polyimide is preferably used as a multilayer film used for a flexible metal-clad laminate that can be used as a high-frequency circuit board. A multilayer film in which an adhesive layer containing thermoplastic polyimide is provided on at least one side of a non-thermoplastic polyimide film whose properties obtained by dynamic viscoelasticity measurement are within a specific range is known, and is a non-thermoplastic polyimide film. Is disclosed to contain a fluororesin (for example, Patent Document 1).

Patent Document 1 discloses a polyimide laminated film having a low dielectric constant, a low dielectric loss tangent, a low moisture absorption factor, and a small dimensional change rate suitable for thermal lamination so as to reduce transmission loss. Along with further speeding up of signals, a flexible printed wiring board (hereinafter, also referred to as FPC) having a small transmission loss is required, and further lower dielectric constant and lower dielectric loss tangent of the substrate material are required.

However, the dielectric loss tangent of polyimide is 0.005 (measured at 10 GHz) even if it is the smallest in Patent Document 1, and although it is effective in reducing transmission loss, it has dimensional stability and heat resistance, which are the conventional required characteristics. In many cases, there is a trade-off between the dielectric properties, and it is considered difficult to dramatically improve the dielectric properties of polyimide alone.

WO2016 / 159060

For this reason, it is desired to provide new materials in case the speed is further increased in the future. Therefore, the present inventors have attempted to combine the material with a material having better dielectric properties than the polyimide material. As a means of compositing, various compositing methods have been studied, including a method of blending different resins having excellent dielectric properties with a polyimide resin and applying different resins having excellent dielectric properties on a polyimide film.

Then, as a resin layer that imparts dielectric properties, an attempt was made to use a thermosetting resin layer having a storage elastic modulus at 20 ° C. of 5.0 GPa or less, which is obtained by measuring dynamic viscoelasticity. Since the thermosetting resin layer exhibits so-called low elasticity, it is generally difficult to satisfy the basic characteristics of the FPC substrate material such as the low coefficient of linear expansion required for FPC and excellent dimensional stability. Further, since the thermosetting resin layer easily transmits flames, it is generally difficult to secure flame retardancy. Therefore, until now, no study has been made on using the thermosetting resin layer as an FPC.

In view of the above situation, as a result of diligent research, the present inventors have used a thermosetting resin having specific thermal properties and excellent dielectric properties, and polyimide is used on both surfaces of the thermosetting resin. It was found that by using a resin laminate coated with a layer, excellent dielectric properties can be realized, and at the same time, low linear expansion coefficient, dimensional stability, and solder heat resistance required for FPC are also exhibited.

That is, the present invention relates to the following.

The present invention is a laminate having a thermosetting resin layer and a polyimide layer, and the thermosetting resin layer has a specific dielectric constant of 3.0 or less and a dielectric loss tangent of 0.003 or less at 10 GHz. Moreover, the storage elastic coefficient at 20 ° C. obtained by measuring the dynamic viscoelasticity is 0.1 GPa or more and 5.0 GPa or less, and the polyimide layer covers both sides of the thermosetting resin layer.

It is preferable that the thickness of the laminate is 25 μm or more, the thickness of the polyimide layer on one side is 0.5 μm or more, and the ratio of the thickness of the polyimide layer to the total thickness of the laminate is 4% or more and 30% or less.

The polyimide layer is preferably a multilayer polyimide layer having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer.

The multilayer polyimide layer is preferably provided with a non-thermoplastic polyimide layer adjacent to the thermosetting resin layer.

The outermost layer of the multilayer polyimide layer is preferably a thermoplastic polyimide layer.

It is preferable that the relative permittivity of the laminate at 10 GHz is 3.0 or less, the dielectric loss tangent is 0.004 or less, and the linear expansion coefficient at 50 ° C. to 250 ° C. is 22 ppm or less.

It is preferable to use a flexible metal-clad laminate provided with a metal layer on at least one surface of the laminate.

It is preferable to use a flexible printed circuit board having the metal-clad laminate.

A laminate for use in a flexible printed circuit board, the laminate having a thermosetting resin layer and a polyimide layer, and the thermosetting resin layer has a specific dielectric constant of 3.0 or less at 10 GHz. The dielectric loss tangent is 0.003 or less, and the storage elastic coefficient at 20 ° C. obtained by measuring the dynamic viscoelasticity is 0.1 GPa or more and 5.0 GPa or less, and the polyimide layer is a thermosetting resin layer. It is preferable to cover both sides.

According to the laminate according to the present invention, the flexible metal-clad laminate in which the metal foil is arranged on the laminate can have a lower transmission loss even more excellent than the conventionally used flexible metal-clad laminate. Is. Therefore, the present invention is useful for high frequency circuit boards.

The resin laminate in the present invention not only satisfies the adhesiveness to the metal foil, solder heat resistance and dimensional stability required for the conventional flexible printed circuit board material, but also can achieve a significant improvement in flame retardancy.

The laminate of the present invention has a thermosetting resin layer and a polyimide layer. The thermosetting resin layer has a relative permittivity of 3.0 or less at 10 GHz, a dielectric loss tangent of 0.003 or less, and a storage elastic modulus at 20 ° C. obtained by measuring dynamic viscoelasticity. It is 1 GPa or more and 5.0 GPa or less. The polyimide layer covers both sides of the thermosetting resin layer.

(Thermosetting resin layer)
The thermosetting resin layer used in the present invention has a relative permittivity of 3.0 or less at 10 GHz and a dielectric loss tangent of 0.003 or less. It greatly contributes to the reduction of FPC transmission loss. The relative permittivity and dielectric loss tangent at 10 GHz are obtained by the cavity resonator method, and the reason for setting the value at 10 GHz is that the region of the electronic signal, which is the high frequency region for the material used for the substrate of the printed wiring board, is This is because a material that can reduce the electrical signal loss at 10 GHz is useful because it is set to 1 GHz to 10 GHz. Since a thermosetting resin is used, the adhesion to the material to be laminated can be improved.

The relative permittivity of the thermosetting resin layer thus obtained is preferably 2.5 or less, more preferably 2.3 or less. The dielectric loss tangent is preferably 0.0025 or less, more preferably 0.0015 or less.

Further, the thermosetting resin layer used in the present invention means a layer that exhibits low elasticity (low storage elastic modulus) after curing the raw material resin. Specifically, low elasticity means that the storage elastic modulus at 20 ° C. obtained by measuring dynamic viscoelasticity is 0.1 GPa or more and 5.0 GPa or less. Further, the storage elastic modulus is preferably 4.0 GPa or less, and more preferably 3.5 GPa or less. The storage elastic modulus of the thermosetting resin layer used in the present invention at 20 ° C. may be as long as it can be laminated, and is 0.1 GPa or more, preferably 0.5 GPa or more. The dynamic viscoelasticity is measured by DMS6100 manufactured by SII Nanotechnology Co., Ltd. in a nitrogen atmosphere to obtain the temperature dependence of the storage elastic modulus at 5 Hz.

A resin used in the present invention having a relative permittivity of 3.0 or less at 10 GHz, a dielectric loss tangent of 0.003 or less, and a storage elasticity at 20 ° C. obtained by measuring dynamic viscoelasticity of 5.0 GPa or less. As a structure having a long-chain hydrocarbon group having a hydrophobic effect or a structure having no polarity that impairs the dielectric property, for example, SF resin manufactured by Hitachi Kasei Co., Ltd., Adflema (registered trademark) manufactured by Namix Co., Ltd., etc. As a structure having no polarity that impairs the dielectric properties, for example, polytetrafluoroethylene (hereinafter, PTFE), liquid crystal polymer (hereinafter, LCP), or the like may be used.

A resin used in the present invention having a relative permittivity of 3.0 or less at 10 GHz, a dielectric loss tangent of 0.003 or less, and a storage elastic modulus of 5.0 GPa or less at 20 ° C. obtained by measuring dynamic viscoelasticity. It is preferable to use a SF resin manufactured by Hitachi Kasei Co., Ltd. because it has excellent heat resistance and adhesiveness to an adjacent polyimide.

In the laminate of the present invention, both sides of the thermosetting resin layer are coated with a polyimide layer. In order to exhibit excellent dielectric properties, the thickness of the thermosetting resin layer is substantially sufficiently thicker than that of the polyimide layer covering both surfaces.

As described above, the storage elastic modulus of the thermosetting resin layer in the present invention at 20 ° C. is 0.1 GPa or more and 5.0 GPa or less, and the dimensional stability is also low. Therefore, as described above, it is considered that the basic characteristics of the FPC substrate material of the thermosetting resin layer deteriorate. However, when the present inventors confirmed these basic characteristics, surprisingly, good results were obtained that sufficiently satisfied the dimensional stability and heat resistance required for the conventional flexible printed circuit board material. It is considered that this is because the storage elastic modulus of the polyimide layer at 20 ° C. is about 6.0 GPa or more, and the dimensional stability is maintained by having the polyimide layers on both sides of the thermosetting resin layer.

Moreover, despite the large proportion of the thermosetting resin layer in the laminate, the configuration of the present invention makes use of the excellent flame retardancy of polyimide, and the laminate also has excellent flame retardancy. .. It is considered that this is because both surfaces of the thermosetting resin layer are coated with the polyimide resin, so that the transmission to the central portion is blocked even when the flame approaches.

The type of polyimide used for the polyimide layers on both sides of the thermosetting resin layer may be the same or different, but from the viewpoint of maintaining the uniformity of linear expansion and suppressing the warp of the resin laminate. It is preferable that they are the same.

In the present invention, the thickness of the resin laminate is preferably 25 μm or more, more preferably 50 μm or more, and the preferable upper limit value is 100 μm or less. The thickness of the polyimide layer on one side is preferably 0.5 μm or more, more preferably 1 μm or more, from the viewpoint of ensuring flame retardancy. From the viewpoint of obtaining excellent dielectric properties, the ratio of the thickness of the polyimide layer to the thickness of the entire laminate is preferably 30% or less, and more preferably 25% or less.

Further, the thickness of the polyimide layers on both sides is preferably the same, the thickness of the polyimide layers on both sides is preferably 0.5 μm or more, and more preferably 1 μm or more. The ratio of the thickness of the polyimide layer (thickness of the polyimide layers on both sides) to the thickness of the entire laminate is preferably 4% or more, and more preferably 5% or more.

From the above, the thickness of the laminate is preferably 25 μm or more, the thickness of the polyimide layer on one side is 0.5 μm or more, and the ratio of the thickness of the polyimide layer to the thickness of the entire laminate is preferably 4% or more, preferably 30% or less. Is preferable. When the relationship between the thicknesses of the thermosetting resin layer and the polyimide layer is within this range, the characteristics as the FPC substrate material and the flame retardancy are improved without causing deterioration of the dielectric properties.

The laminate of the present invention can have a relative permittivity of 3.0 or less and a dielectric loss tangent of 0.004 or less. The relative permittivity of the laminate is more preferably 2.8 or less, and particularly preferably 2.5 or less. The dielectric loss tangent is preferably 0.0035 or less, more preferably 0.003 or less. The coefficient of linear expansion is preferably 22 ppm or less, more preferably 20 ppm or less. The FPC obtained as described above is not only excellent in electrical characteristics, but also excellent in characteristics as an FPC such as a low coefficient of linear expansion and excellent dimensional stability.

(Polyimide layer)
The polyimide layer used in the present invention is preferably a multilayer polyimide layer composed of a non-thermoplastic polyimide layer and a thermoplastic polyimide layer. The multilayer polyimide layer is preferably provided so that the non-thermoplastic polyimide layer is adjacent to the thermosetting resin layer. That is, it is preferably composed of a thermoplastic polyimide layer / a non-thermoplastic polyimide layer / a thermosetting resin layer / a non-thermoplastic polyimide layer / a thermoplastic polyimide layer.

Hereinafter, a raw material monomer of polyamic acid which is a precursor of non-thermoplastic polyimide used for a non-thermoplastic polyimide layer, production of polyamic acid which is a precursor of the non-thermoplastic polyimide, a method for producing a non-thermoplastic polyimide film, heat. The plastic polyimide layer will be described in detail in this order.

(Raw material monomer for polyamic acid, which is a precursor of non-thermoplastic polyimide)
The raw material monomer of polyamic acid, which is a precursor of non-thermoplastic polyimide in the present invention, is a non-thermoplastic polyimide imidized with polyamic acid, which is a precursor, and has solder heat resistance and dimensional stability required for conventional flexible printed substrate materials. It has property and flame retardancy, and is not particularly limited as long as it is controlled by the primary structure and the manufacturing method. Diamines and acid dianhydrides commonly used in the synthesis of polyamic acids can be used.

The aromatic diamine is not particularly limited as long as the effects of the present invention can be exhibited, but is 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminodiphenyl propane, 4,4'-. Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4,4'-oxydianiline, 3,3'-oxydianiline, 3, 4'-Oxydianiline, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenylN-methylamine, 4 , 4'-Diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (3-aminophenoxy) phenyl} Pulmonate, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (3) -Aminophenoxy) benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis (4-aminophenoxyphenyl) propane and the like can be mentioned, and these can be used alone or in combination of two or more. ..

The acid dianhydride compound that can be used as a raw material monomer for polyamic acid is not particularly limited as long as the effects of the present invention can be exhibited, but pyromellitic hydride, 2,3,6,7-naphthalenetetracarboxylic acid. Dianhydride, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetra Carboxyl dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic hydride, 2,2', 3,3'-benzophenone tetracarboxylic hydride, 4,4'-oxyphthalic acid dianhydride Anhydride, 3,4'-oxyphthalic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propanoic hydride, 3,4,9,10-perylenetetracarboxylic hydride, Bis (3,4-dicarboxyphenyl) propanoic dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane Dianhydride, bis (2,3-dicarboxyphenyl) metanic dianhydride, bis (3,4-dicarboxyphenyl) ethaneic hydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) Phenyl) sulfonic acid dianhydride, p-phenylenebis (trimellitic acid monoesteric anhydride), ethylenebis (trimellitic acid monoesteric anhydride), bisphenol A bis (trimellitic acid monoesteric anhydride) and Examples thereof include similar products.

(Manufacture of polyamic acid, which is a precursor of non-thermoplastic polyimide)
As the organic solvent used in the production of the polyamic acid which is a precursor of the non-thermoplastic polyimide, any solvent can be used as long as it is a solvent that dissolves the non-thermoplastic polyamic acid. For example, an amide solvent, that is, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like are preferable, and N, N-dimethylformamide and N, N-dimethylacetamide can be more preferably used. .. The solid content concentration of the polyamic acid, which is a precursor of the non-thermoplastic polyimide, is not particularly limited, and if it is in the range of 5% by weight to 35% by weight, the non-thermoplastic polyimide film has sufficient mechanical strength. Polyamic acid, which is a precursor of thermoplastic polyimide, can be obtained.

The order of addition of the raw materials aromatic diamine and aromatic acid dianhydride is not particularly limited, but the characteristics of the obtained non-thermoplastic polyimide can be controlled not only by controlling the chemical structure of the raw materials but also by controlling the order of addition. It is possible to do.

A filler can be added to the non-thermoplastic polyamic acid for the purpose of improving various properties of the film such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness. Any filler may be used, and preferred examples thereof include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

(Manufacturing method of non-thermoplastic polyimide film)
To obtain the non-thermoplastic polyimide film in the present invention, the following steps i) A polyamic acid solution which is a precursor of the non-thermoplastic polyimide by reacting an aromatic diamine with an aromatic acid dianhydride in an organic solvent (hereinafter, , Also called non-thermoplastic polyimide)
ii) A step of casting a film-forming dope containing the non-thermoplastic polyamic acid solution from a die onto a support to form a resin layer (sometimes referred to as a liquid film).
iii) A step of heating a resin layer on a support to form a self-supporting gel film, and then peeling the gel film from the support.
iv) A step of further heating to imidize the remaining amic acid and drying to obtain a non-thermoplastic polyimide film.
Is preferably included.

The steps after ii) are roughly classified into a thermal imidization method and a chemical imidization method. The thermal imidization method is a method in which a polyamic acid solution is cast on a support as a film-forming dope without using a dehydration ring closure agent or the like, and imidization is promoted only by heating. On the other hand, the chemical imidization method is a method of promoting imidization by using a polyamic acid solution to which at least one of a dehydration ring-closing agent and a catalyst is added as an imidization accelerator as a film-forming dope. Either method may be used, but the chemical imidization method is more productive.

As the dehydration ring closure agent, an acid anhydride typified by acetic anhydride can be preferably used. As the catalyst, tertiary amines such as aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines can be preferably used.

As the support for spreading the film-forming dope, a glass plate, an aluminum foil, an endless stainless belt, a stainless drum, or the like can be preferably used. Heating conditions are set according to the thickness of the finally obtained film and the production rate, and after at least one of partial imidization and drying is performed, the film is peeled off from the support and is referred to as a polyamic acid film (hereinafter referred to as gel film). ).

The edges of the gel film were fixed to avoid shrinkage during curing and dried, water, residual solvent, imidization accelerators were removed from the gel film, and the remaining amic acid was completely imidized. A film containing polyimide can be obtained. The heating conditions may be appropriately set according to the thickness of the finally obtained film and the production rate.

(Thermoplastic polyimide layer)
The thermoplastic polyimide contained in the thermoplastic polyimide layer in the present invention is obtained by imidizing the polyamic acid as a precursor thereof.

In FPC, an insulating film layer such as polyimide is used as a core film, and a flexible metal-clad laminate is bonded to the surface of the core film by heating and pressure-bonding a metal foil layer via an adhesive layer made of various adhesive materials. It is obtained by manufacturing on a plate and further forming a circuit pattern. Epoxy resins and acrylic resins have been conventionally used for the adhesive layer, but these have poor heat resistance and their uses are limited. However, a two-layer flexible printed wiring board (hereinafter, also referred to as a two-layer FPC) using a thermoplastic polyimide as an adhesive layer is expected to further increase in demand because it is excellent in heat resistance and flexibility.

The aromatic diamine and aromatic tetracarboxylic acid dianhydride used for the polyamic acid which is the precursor of the thermoplastic polyimide used in the present invention include the same ones used for the non-thermoplastic polyimide layer. In order to obtain a thermoplastic polyimide film, it is preferable to react a flexible diamine with an acid dianhydride. Examples of flexible diamines are 4,4'-diaminodiphenyl ether, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 1,3-bis. Examples thereof include (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, and 2,2-bis (4-aminophenoxyphenyl) propane. Examples of acid dianhydrides that are preferably combined with these diamines include pyromellitic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4, Examples thereof include 4'-biphenyltetracarboxylic acid dianhydride and 4,4'-oxydiphthalic acid dianhydride.

In the method for producing a thermoplastic polyamic acid in the present invention, the thermoplastic polyimide obtained by imidizing the obtained polyamic acid has adhesiveness to a metal foil, solder heat resistance, and dimensional stability, which are required for conventional flexible printed substrate materials. Any known method can be used as long as it is flame-retardant. For example, the following steps (A) to (Ac):
(A-a) A step of reacting an aromatic diamine with an aromatic acid dianhydride in an organic solvent in an excess of the aromatic diamine to obtain a prepolymer having amino groups at both ends.
(A-b) A step of additionally adding an aromatic diamine having a structure different from that used in the step (A-a).
(Ac) Further, the aromatic acid dianhydride having a structure different from that used in the step (Aa) is substantially equimolar of the aromatic diamine and the aromatic acid dianhydride in all the steps. The process of adding and polymerizing so that
Can be manufactured by.

Alternatively, the following steps (B-a) to (B-c):
(BA) Aromatic diamine and aromatic acid dianhydride are reacted in an organic polar solvent with an excess of aromatic acid dianhydride to form a prepolymer having acid anhydride groups at both ends. Getting process,
(B-b) A step of additionally adding an aromatic acid dianhydride having a structure different from that used in the step (B-a).
(B-c) Further, the aromatic diamine having a structure different from that used in the step (BA) is used so that the aromatic diamine and the aromatic acid dianhydride in all the steps are substantially equimolar. The process of adding and polymerizing,
It is also possible to obtain polyamic acid by passing through.

(Solid content concentration of polyamic acid)
The solid content concentration of the polyamic acid of the present invention is not particularly limited, and is usually obtained in a concentration of 5% by weight to 35% by weight, preferably 10% by weight to 30% by weight. When the concentration is in this range, an appropriate molecular weight and solution viscosity are obtained.

(Manufacturing method of a laminate having a thermosetting resin layer and a polyimide layer)
The method for producing a laminate having a thermosetting resin layer and a polyimide layer in the present invention will be described in detail. In the method for producing a laminate in the present invention, for example, a non-thermoplastic polyimide film obtained by synthesizing a non-thermoplastic polyamic acid in the above i) and then proceeding to the above steps ii) to iv) is used as a thermosetting resin film. It is sandwiched between both sides of the resin and laminated while curing the thermosetting resin by heat crimping or the like. After that, when the thermoplastic polyimide layer is provided, it is also possible to provide the layer by coating.

When the thermoplastic polyimide layer is provided by coating, the thermoplastic polyamic acid may be applied and then imidized, or a thermoplastic polyimide solution capable of forming the thermoplastic polyimide layer may be applied and dried. May be good. FCCL can be manufactured by providing a metal layer on the laminate thus obtained.

By laminating with a metal foil using the laminate of the present invention, a flexible metal-clad laminate processed into a two-layer FPC can be manufactured. As a means for forming the laminate on the metal foil, there is a means (thermal lamination method) for obtaining a flexible metal-clad laminate by laminating the metal foil by heating and pressurizing after obtaining the laminate as described above. Be done. As the means and conditions for laminating the metal foils, conventionally known ones may be appropriately selected.

The metal foil is not particularly limited, and any metal foil can be used. For example, copper, stainless steel, nickel, aluminum, alloys of these metals, and the like can be preferably used. Further, in a general metal-clad laminate, copper such as rolled copper and electrolytic copper is often used, but it can also be preferably used in the present invention.

Further, as the metal foil, one having various characteristics such as surface treatment and surface roughness can be selected according to the purpose. Further, a rust preventive, a heat resistant treatment agent or an adhesive may be applied to the surface of the metal foil. The thickness of the metal foil is not particularly limited as long as it can exhibit a sufficient function depending on the application. The metal layer of FCCL thus obtained can be etched to obtain FPC.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The methods for evaluating the relative permittivity, dielectric loss tangent, linear expansion coefficient, flame retardancy, peel strength of flexible metal leaf laminate, moisture absorption solder heat resistance, and dimensional change rate in the synthetic examples, examples, and comparative examples are as follows. It is as follows.

<Measurement of relative permittivity and dielectric loss tangent>
The permittivity and the dielectric loss tangent were measured using a network analyzer 8719C manufactured by Hewlett-Packard Co., Ltd. and a cavity resonator vibration method dielectric constant measuring device CP511 manufactured by Kanto Denshi Applied Development Co., Ltd. The sample was cut into 2 mm x 100 mm and 23 ° C./50% R. H. The measurement was performed after humidity control for 24 hours in the environment. The measurement was performed at 10 GHz.

<Water absorption rate>
The laminate cut out to 50 mm × 50 mm was dried at 150 ° C. × 30 min, the weight (w1) in an absolutely dry state was measured, and then the laminate was immersed in water. After 24 hours, the test piece was taken out from water, the water on the surface was wiped off, and the weight (w2) was measured. The water absorption rate was calculated from the formula (1) using the obtained w1 and w2.

Water absorption rate (%) = {(w2-w1) / w1} × 100 ... Equation (1)

<Measurement of coefficient of linear expansion (CTE)>
The coefficient of linear expansion is 40 ° C to -10 ° C after raising the temperature from -10 ° C to 300 ° C at 10 ° C / min using a thermomechanical analyzer manufactured by SII Nanotechnoguchiji Co., Ltd., trade name: TMA / SS6100. The temperature was further increased at 10 ° C./min after cooling at / min, and the value at 50 to 250 ° C. at the time of the second temperature increase was estimated. The measurement conditions are shown below.
Sample shape: width 3 mm, length 10 mm
Load: 1g
Measurement temperature range: -10 ° C to 300 ° C
Atmosphere: Under the air atmosphere

<Flame retardant>
A test piece conforming to the UL-94 standard was prepared using a laminate cut out to a size of 200 mm × 50 mm, and a combustion test was carried out in accordance with the VTM test. The case where the judgment standard of VTM-0 was passed was evaluated as ◯ (good), and the case where it failed was evaluated as × (bad).

<Peel strength>
The peel strength when the 1 mm metal wiring pattern formed on the double-sided flexible metal-clad laminate obtained in Examples and Comparative Examples was peeled off at 90 degrees was measured. Peel strength was evaluated according to JISC-6471.

<Hygroscopic solder heat resistance>
The double-sided flexible metal-clad laminates obtained in Examples and Comparative Examples were cut into 3.5 cm squares so that a 2.5 cm square copper foil layer remained in the center of the sample on one side (referred to as side A for convenience). Five samples were prepared by removing the excess copper foil layer by etching so that the copper foil layer remained on the entire surface of the opposite surface (referred to as the B surface for convenience). The obtained samples were subjected to 85 ° C. and 85% R. H. Under the humidified conditions of No. 1, it was left for 72 hours to perform a moisture absorption treatment. After the moisture absorption treatment, each sample was immersed in a solder bath at 300 ° C. for 10 seconds. For the samples after solder immersion, the copper foil layer on the B side is completely removed by etching, and if there is no change in the appearance of the overlapping part of the copper foil in all five samples, ○ (good), five samples When any of whitening, swelling, and peeling of the copper foil was confirmed in one or more of the samples, it was evaluated as x (bad).

<Measurement of dimensional change rate>
Based on JISC6481, four holes were formed in the flexible metal-clad laminate, and the distances between the holes were measured. Next, after performing an etching step to remove the metal leaf from the flexible metal-clad laminate, 23 ° C./55% R.M. H. It was left in the constant temperature room for 24 hours. After that, the distances of the four holes were measured in the same manner as before the etching step. The measured value of the distance of each hole before removing the metal foil was set to D1, and the measured value of the distance of each hole after removing the metal foil was set to D2, and the dimensional change rate before and after etching was obtained by the following equation (2). The dimensional change rate was measured in both the MD direction (film transport direction) and the TD direction (direction orthogonal to the film transport direction).

Dimensional change rate (%) = {(D2-D1) / D1} x 100 ... Equation (2)

<Measurement of dynamic viscoelasticity>
Measurements were made using a DMS6100 manufactured by SII Nanotechnology Inc. (sample size width 9 mm, length 40 mm) at a frequency of 5 Hz and a temperature rise rate of 3 ° C./min in a temperature range of −50 to 450 ° C. The storage elastic modulus at 20 ° C. was estimated from the curve plotting the storage elastic modulus with respect to temperature.

<Synthesis of non-thermoplastic polyimide precursor>
(Synthesis Example 1)
In a glass flask with a capacity of 2000 ml, 657.8 g of N, N-dimethylformamide (hereinafter, also referred to as DMF), 10.5 g of diaminodiphenyl ether (hereinafter, also referred to as ODA) and 2,2-bis [4- (4- (4- (4- (4- (4- (4-) 4-) Aminophenoxy) phenyl] Propane (hereinafter, also referred to as BAPP) 32.4 g was added, and while stirring under a nitrogen atmosphere, 17.0 g of benzophenone tetracarboxylic acid dianhydride (hereinafter, also referred to as BTDA) and pyromellitic acid dianhydride were added. 14.3 g of anhydride (hereinafter, also referred to as PMDA) was gradually added. After visually confirming that BTDA and PMDA were dissolved, 14.2 g of p-phenylenediamine (hereinafter, also referred to as PDA) was added, and the mixture was stirred for 5 minutes. Subsequently, after adding 28.7 g of PMDA, the mixture was stirred for 30 minutes. Finally, a solution prepared by dissolving 1.7 g of PMDA in DMF so as to have a solid content concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while paying attention to the increase in viscosity. When the viscosity at 23 ° C. reached 2000 poisons, the addition and stirring were stopped to obtain a polyamic acid solution.

(Synthesis Example 2)
Add 625.9 g of DMF and 23.45 g of PDA to a glass flask with a capacity of 2000 ml, and while stirring in a nitrogen atmosphere, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride (hereinafter, BPDA). (Also referred to as) was gradually added in an amount of 57.4 g. After visually confirming that BPDA was dissolved, add 17.1 g of 4,4'-bis (4-aminophenoxy) biphenyl (hereinafter, also referred to as BABP) and 19.0 g of BAPP, and stir in a nitrogen atmosphere. , 6.4 g of BPDA was gradually added. After visually confirming that BPDA was dissolved, 14.4 g of 4,4'-oxydiphthalic anhydride (hereinafter, also referred to as ODPA) and 8.1 g of PMDA were added, and the mixture was stirred for 30 minutes, and then 116 g of PTFE particles were added. , Stirred for another 30 minutes. After stirring, a solution prepared by dissolving 1.7 g of PMDA in DMF so as to have a solid content concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while paying attention to the increase in viscosity. When the viscosity at 23 ° C. reached 2000 poisons, the addition and stirring were stopped to obtain a polyamic acid solution.

<Synthesis of thermoplastic polyimide precursor>
(Synthesis Example 3)
While keeping the inside of the reaction system at 20 ° C., 43.6 g of BAPP was added to 323.0 g of DMF, and while stirring in a nitrogen atmosphere, 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride ( Hereinafter, 43.6 g (also referred to as BPDA) was gradually added. After visually confirming that BPDA was dissolved, 19.0 g of PMDA was added and the mixture was stirred for 30 minutes. A solution prepared by dissolving 0.7 g of PMDA in DMF so as to have a solid content concentration of 7.2% was gradually added to the above reaction solution while paying attention to the increase in viscosity, and the viscosity became 800 poisons. When it reached, the polymerization was terminated.

<Manufacturing of laminated body>
(Example 1)
An imidization accelerator composed of acetic anhydride / isoquinoline / DMF (weight ratio 7.2 / 2.2 / 10.6) was added to the polyamic acid solution obtained in Synthesis Example 2 at a weight ratio of 50% with respect to the polyamic acid solution. It was added, continuously stirred with a mixer, extruded from a T-die and cast on a stainless steel endless belt. After heating this resin film at 120 ° C. × 60 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to the tenter clip, and at 250 ° C. × 8 seconds, 350 ° C. × 8 seconds, 400 ° C. × 60 seconds. It was dried and imidized to obtain a polyimide film having a thickness of 4 μm. The obtained polyimide film was heat-bonded to both sides of a 38 μm SF resin (product name: AS-8000) film manufactured by Hitachi Kasei Co., Ltd. under the conditions of 185 ° C., 2.0 MPa, and 90 min, and then the obtained laminate was obtained. The polyamic acid solution obtained in Synthesis Example 3 was applied to both sides of the above so that the final single-sided thickness was 3.0 μm, and dried at 120 ° C. × 120 seconds. Subsequently, it was heated at 350 ° C. for 11 seconds for imidization to obtain a laminate having a total thickness of 52 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. Thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, and the peel strength, moisture absorption solder heat resistance, and dimensional change rate of the obtained flexible metal-clad laminate were determined. evaluated. The results are shown in Table 1.

(Example 2)
Using the polyamic acid solution obtained in Synthesis Example 2, a polyimide film having a thickness of 4 μm obtained in the same manner as in the production of the polyimide film used in Example 1 was used as a 28 μm SF resin manufactured by Hitachi Kasei Co., Ltd. (product name). : AS-400HS) After heat-pressing on both sides of the film under the conditions of 185 ° C., 2.0 MPa, 90 min, the polyamic acid solution obtained in Synthesis Example 3 was applied to both sides of the obtained laminate to the final single-sided thickness. The film was applied so as to have a thickness of 2.0 μm, and dried at 120 ° C. × 120 seconds. Subsequently, imidization was carried out by heating at 350 ° C. for 11 seconds to obtain a laminate having a total thickness of 40 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, both sides of the obtained laminate were heat-laminated under the same conditions as in Example 1, and the peel strength, moisture absorption solder heat resistance, and dimensional change rate of the obtained flexible metal-clad laminate were evaluated. The results are shown in Table 1.

(Example 3)
An imidization accelerator composed of acetic anhydride / isoquinoline / DMF (weight ratio 7.2 / 2.2 / 10.6) was added to the polyamic acid solution obtained in Synthesis Example 1 at a weight ratio of 50% with respect to the polyamic acid solution. It was added, continuously stirred with a mixer, extruded from a T-die and cast on a stainless steel endless belt. After heating this resin film at 120 ° C. × 60 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to the tenter clip, and at 250 ° C. × 8 seconds, 350 ° C. × 8 seconds, 400 ° C. × 60 seconds. It was dried and imidized to obtain a polyimide film having a thickness of 3 μm. The obtained polyimide film was heat-bonded to both sides of a 40 μm SF resin (product name: AS-8000) film manufactured by Hitachi Kasei Co., Ltd. under the conditions of 185 ° C., 2.0 MPa, and 90 min, and then the obtained laminate was obtained. The polyamic acid solution obtained in Synthesis Example 3 was applied to both sides of the above so that the final single-sided thickness was 3.0 μm, and dried at 120 ° C. × 120 seconds. Subsequently, it was heated at 350 ° C. for 11 seconds for imidization to obtain a laminate having a total thickness of 52 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption, flame retardancy, and coefficient of linear expansion (CTE).

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. Thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, and the peel strength, moisture absorption solder heat resistance, and dimensional change rate of the obtained flexible metal-clad laminate were determined. evaluated. The results are shown in Table 1.

(Example 4)
Using the polyamic acid solution obtained in Synthesis Example 1, a polyimide film having a thickness of 3 μm obtained in the same manner as in the production of the polyimide film used in Example 3 was used as a 38 μm SF resin manufactured by Hitachi Kasei Co., Ltd. (product name). : AS-400HS) After heat-pressing on both sides of the film under the conditions of 185 ° C., 2.0 MPa, 90 min, the polyamic acid solution obtained in Synthesis Example 3 was applied to both sides of the obtained laminate to the final single-sided thickness. The film was applied so as to have a thickness of 3.0 μm, and dried at 120 ° C. × 120 seconds. Subsequently, it was heated at 350 ° C. for 11 seconds for imidization to obtain a laminate having a total thickness of 50 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, both sides of the obtained laminate were heat-laminated under the same conditions as in Example 1, and the peel strength, moisture absorption solder heat resistance, and dimensional change rate of the obtained flexible metal-clad laminate were evaluated. The results are shown in Table 1.

(Comparative Example 1)
An imidization accelerator composed of acetic anhydride / isoquinoline / DMF (weight ratio 7.2 / 2.2 / 10.6) was added to the polyamic acid solution obtained in Synthesis Example 1 at a weight ratio of 50% with respect to the polyamic acid solution. It was added, continuously stirred with a mixer, extruded from a T-die and cast on a stainless steel endless belt. After heating this resin film at 120 ° C. × 120 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to the tenter clip, and at 250 ° C. × 11 seconds, 350 ° C. × 11 seconds, 450 ° C. × 120 seconds. It was dried and imidized to obtain a polyimide film having a thickness of 17 μm. The obtained polyimide film was diluted with toluene so that the solid content concentration was 20%, and SF resin (product name: SFR-2300MR) manufactured by Hitachi Kasei Co., Ltd. was applied to both sides of the polyimide film so that the final one-sided thickness was 4 μm. And dried at 110 ° C. x 600 seconds. Subsequently, it was heat-cured at 185 ° C. for 60 minutes to obtain a laminate having a total thickness of 25 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., a laminating pressure of 265 N / cm (27 kgf / cm), and a laminating speed of 1.0 m / min, the resin layer in the laminated body flowed to obtain a suitable flexible metal-clad laminate. I couldn't.

(Comparative Example 2)
Hitachi Kasei Co., Ltd. with a thickness of 6.5 μm on both sides of a polyimide film with a thickness of 12.5 μm obtained by the same method as the production of the polyimide film used in Comparative Example 1 using the polyamic acid solution obtained in Synthesis Example 1. A SF resin (product name: AS-8000) film manufactured by the company was heat-bonded at 70 ° C. and 0.4 MPa to obtain a laminate having a total thickness of 25.5 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., a laminating pressure of 265 N / cm (27 kgf / cm), and a laminating speed of 1.0 m / min, the resin layer in the laminated body flowed to obtain a suitable flexible metal-clad laminate. I couldn't.

(Comparative Example 3)
Hitachi Kasei Co., Ltd. with a thickness of 6.5 μm on both sides of a polyimide film with a thickness of 17.0 μm obtained by the same method as the production of the polyimide film used in Comparative Example 1 using the polyamic acid solution obtained in Synthesis Example 1. A company-made SF resin (product name: AS-8000) film was heat-bonded at 70 ° C. and 0.4 MPa to obtain a laminate having a total thickness of 30 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., a laminating pressure of 265 N / cm (27 kgf / cm), and a laminating speed of 1.0 m / min, the resin layer in the laminated body flowed to obtain a suitable flexible metal-clad laminate. I couldn't.

(Comparative Example 4)
Using the polyamic acid solution obtained in Synthesis Example 1, a polyimide film having a thickness of 17.0 μm obtained in the same manner as in the production of the polyimide film used in Comparative Example 1 was manufactured by Hitachi Kasei Co., Ltd. with a thickness of 13 μm on both sides. A SF resin (product name: AS-8000) film was heat-bonded at 70 ° C. and 0.4 MPa to obtain a laminate having a total thickness of 43 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., a laminating pressure of 265 N / cm (27 kgf / cm), and a laminating speed of 1.0 m / min, the resin layer in the laminated body flowed to obtain a suitable flexible metal-clad laminate. I couldn't.

(Comparative Example 5)
An imidization accelerator composed of acetic anhydride / isoquinoline / DMF (weight ratio 7.2 / 2.2 / 10.6) was added to the polyamic acid solution obtained in Synthesis Example 2 at a weight ratio of 50% with respect to the polyamic acid solution. It was added, continuously stirred with a mixer, extruded from a T-die and cast on a stainless steel endless belt. After heating this resin film at 120 ° C. × 120 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to the tenter clip, and at 250 ° C. × 25 seconds, 350 ° C. × 20 seconds, 400 ° C. × 200 seconds. It was dried and imidized to obtain a polyimide film having a thickness of 44 μm. The polyamic acid solution obtained in Synthesis Example 3 was applied to both sides of the obtained polyimide film so that the final single-sided thickness was 3.0 μm, and dried at 120 ° C. × 120 seconds. Subsequently, it was heated at 350 ° C. for 11 seconds for imidization to obtain a laminate having a total thickness of 50 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. Thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, and the peel strength, moisture absorption solder heat resistance, and dimensional change rate of the obtained flexible metal-clad laminate were determined. evaluated. The results are shown in Table 1.

(Comparative Example 6)
An imidization accelerator composed of acetic anhydride / isoquinoline / DMF (weight ratio 7.2 / 2.2 / 10.6) was added to the polyamic acid solution obtained in Synthesis Example 2 at a weight ratio of 50% with respect to the polyamic acid solution. It was added, continuously stirred with a mixer, extruded from a T-die and cast on a stainless steel endless belt. After heating this resin film at 120 ° C. × 240 seconds, the self-supporting gel film is peeled off from the endless belt and fixed to the tenter clip, and at 250 ° C. × 22 seconds, 350 ° C. × 35 seconds, 400 ° C. × 240 seconds. It was dried and imidized to obtain a polyimide film having a thickness of 34 μm. The polyamic acid solution obtained in Synthesis Example 3 was applied to both sides of the obtained polyimide film so that the final single-sided thickness was 8.0 μm, and dried at 120 ° C. × 240 seconds. Subsequently, it was heated at 350 ° C. for 25 seconds for imidization to obtain a laminate having a total thickness of 50 μm. The obtained laminate was used to evaluate the relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metal Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. Thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, and the peel strength, moisture absorption solder heat resistance, and dimensional change rate of the obtained flexible metal-clad laminate were determined. evaluated. The results are shown in Table 1.

(Comparative Example 7)
Using the polyamic acid solution obtained in Synthesis Example 2, a polyimide film having a thickness of 17.0 μm obtained in the same manner as in the production of the polyimide film used in Comparative Example 6 was used for relative permittivity, dielectric loss tangent, and water absorption. Rate, flame retardancy and CTE were evaluated.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metals) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, the laminated body did not adhere to the copper foil, and a suitable flexible metal-clad laminate was obtained. I couldn't.

(Comparative Example 8)
Using the polyamic acid solution obtained in Synthesis Example 2, a polyimide film having a thickness of 34.0 μm obtained in the same manner as in the production of the polyimide film used in Comparative Example 6 was used for relative permittivity, dielectric loss tangent, and water absorption. Rate, flame retardancy and CTE were evaluated.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Metals) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, the laminated body did not adhere to the copper foil, and a suitable flexible metal-clad laminate was obtained. I couldn't.

(Comparative Example 9)
The relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE were evaluated using a 38 μm SF resin (product name: AS-8000) film manufactured by Hitachi Kasei Co., Ltd.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Mining & Smelting Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, the resin layer in the laminated body flowed, and a suitable flexible metal-clad laminate was obtained. I couldn't get it.

(Comparative Example 10)
The relative permittivity, dielectric loss tangent, water absorption rate, flame retardancy, and CTE were evaluated using a 33 μm SF resin (product name: AS-400HS) film manufactured by Hitachi Kasei Co., Ltd.

Further, 12 μm electrolytic copper foil (3EC-M3S-HTE, manufactured by Mitsui Mining & Smelting Co., Ltd.) was arranged on both sides of the obtained laminate, and protective films (Apical 125 NPI; manufactured by Kaneka) were used on both sides of the copper foil to prepare the lamination temperature. When thermal laminating was performed under the conditions of 360 ° C., laminating pressure 265 N / cm (27 kgf / cm), and laminating speed 1.0 m / min, the resin layer in the laminated body flowed, and a suitable flexible metal-clad laminate was obtained. I couldn't get it.

From Table 1, in the example having the thermosetting resin layer of the present invention in the center and having the polyimide layers on both sides of the thermosetting resin layer, the relative permittivity is higher than that of Comparative Examples 5 to 8 having only the polyimide layer. And the dielectric loss tangent decreased, and the dielectric characteristics became good. Further, in Examples 1 to 4, although the thermosetting resin layer having a low storage elastic modulus is used, the dimensional stability is about the same as that of Comparative Examples 5 and 6 having only the polyimide layer, and the linear expansion coefficient is also the same. It became a degree. That is, it was possible to suppress an increase in the dimensional stability rate and an increase in the coefficient of linear expansion.

In Comparative Examples 1 to 4 having a polyimide layer in the center and thermosetting resin layers on both sides of the polyimide layer, and Comparative Examples 9 and 10 having only a thermosetting resin layer, the flame retardancy was low. That is, it was found that it was difficult to use as FCCL.

Claims (7)

A laminate having a thermosetting resin layer and a polyimide layer, the thermosetting resin layer having a specific dielectric constant of 3.0 or less at 10 GHz, a dielectric loss tangent of 0.003 or less, and moving. The storage elasticity at 20 ° C. obtained by measuring the viscoelasticity is 0.1 GPa or more and 5.0 GPa or less, and the polyimide layer covers both sides of the thermosetting resin layer .
The thickness of the laminate is 25 μm or more, the thickness of the polyimide layer on one side is 0.5 μm or more, and the ratio of the thickness of the polyimide layers on both sides to the total thickness of the laminate is 4% or more and 30% or less.
The polyimide layer is a multilayer polyimide layer having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer.
The multilayer polyimide layer is provided so that the non-thermoplastic polyimide layer is adjacent to the thermosetting resin layer.
The thermosetting resin layer is a laminate characterized by being made of SF resin. The laminate according to claim 1 (excluding those in which a metal wiring pattern is formed between the thermosetting resin layer and the multilayer polyimide layer). The laminate according to claim 1 or 2, wherein the outermost layer of the multilayer polyimide layer is a thermoplastic polyimide layer. Claims 1 to 3 are characterized in that the relative permittivity of the laminate at 10 GHz is 3.0 or less, the dielectric loss tangent is 0.004 or less, and the linear expansion coefficient at 50 ° C to 250 ° C is 22 ppm or less. The laminate according to any one of the above items. A flexible metal-clad laminate in which a metal layer is further provided on at least one surface of the laminate according to any one of claims 1 to 4. A flexible printed circuit board having the metal-clad laminate according to claim 5. A laminate for use in a flexible printed circuit board, the laminate having a thermosetting resin layer and a polyimide layer, and the thermosetting resin layer has a specific dielectric constant of 3.0 or less at 10 GHz. The dielectric loss tangent is 0.003 or less, and the storage elastic coefficient at 20 ° C. obtained by measuring the dynamic viscoelasticity is 0.1 GPa or more and 5.0 GPa or less, and the polyimide layer is the thermosetting resin layer. of it has been coated on both sides,
The thickness of the laminate is 25 μm or more, the thickness of the polyimide layer on one side is 0.5 μm or more, and the ratio of the thickness of the polyimide layers on both sides to the total thickness of the laminate is 4% or more and 30% or less.
The polyimide layer is a multilayer polyimide layer having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer.
The multilayer polyimide layer is provided so that the non-thermoplastic polyimide layer is adjacent to the thermosetting resin layer.
The thermosetting resin layer is a laminate characterized by being made of SF resin.