WO2020213515A1 - Laminate, method for manufacturing printed circuit board, printed circuit board, and antenna - Google Patents

Abstract

The present invention provides a laminate (metal clad laminate) which comprises a dielectric layer that has a low water absorption rate and excellent dielectric characteristics, heat resistance, and adhesion, and a metal foil layer, and which has excellent properties as materials or the like of printed circuit boards such as flexible printed circuit boards and rigid printed circuit boards.　The laminate has at least a three-layer structure and includes the metal foil layer, a non-thermoplastic polyimide layer P, and a tetrafluoroethylene polymer layer F, at least one of the outermost layers being the metal foil layer. The layer F is present on at least one surface of the layer P. The layer P has a water absorption rate of less than 1.5%, and the absolute value of the coefficient of linear expansion thereof is 25 ppm/°C or less.

Description

Laminates, printed circuit board manufacturing methods, printed circuit boards and antennas

The present invention relates to a laminate, a method for manufacturing a printed circuit board, a printed circuit board, and an antenna.

With the development of the information and communication society, the amount of data transferred is increasing. As a result, the frequency of radio waves used for information transmission is steadily rising. For example, a printed circuit board is used as a transmission line through which an electric signal is passed. When a high-frequency electric signal is passed through the transmission line, the higher the frequency, the greater the deterioration (loss).
The dielectric material used for the printed circuit board is required to have low dielectric constant, low dielectric loss tangent and low water absorption in order to reduce the loss of electric signals. Examples of such a dielectric material include tetrafluoroethylene-based polymers. However, when a tetrafluoroethylene polymer is used, the dimensional stability and mechanical strength of the printed circuit board tend to decrease. Non-thermoplastic polyimides have been proposed as alternatives to such tetrafluoroethylene-based polymers (see Patent Documents 1 to 3).

International Publication No. 2016/159060 International Publication No. 2018/061727 JP-A-2018-150544

A printed circuit board formed from a laminate having a non-thermoplastic polyimide as a dielectric layer has excellent dielectric properties due to its molecular skeleton characteristics. However, the present inventors have first found that the dielectric properties of the printed circuit board are still unstable due to the water absorption of the non-thermoplastic polyimide.
Further, due to the above characteristics, the heat resistance of the non-thermoplastic polyimide is not yet sufficient, and when the laminate is subjected to a solder float process, which is a mounting process of a printed circuit board, the dielectric layer is easily peeled off or swelled, and printing The present inventors have also found that it is difficult to efficiently manufacture a substrate.
The present invention is a laminate (metal-clad) having a dielectric layer in which a non-thermoplastic polyimide and a tetrafluoroethylene polymer are composited, which are excellent in dielectric properties, heat resistance and adhesion and have a low water absorption rate, and a metal foil layer. The purpose is to provide a laminate). Another object of the present invention is to provide a printed circuit board having excellent physical properties and reduced transmission loss, a method for manufacturing the printed circuit board, and an antenna.

The present invention has the following aspects.
[1] A laminated body having at least a three-layer structure having a metal foil layer, a layer P of non-thermoplastic polyimide, and a layer F of a tetrafluoroethylene-based polymer, and at least one of the outermost layers is a metal foil layer. A laminate in which the layer F is present on at least one surface of the layer P, the water absorption rate of the layer P is less than 1.5%, and the absolute value of the linear expansion coefficient is 25 ppm / ° C. or less.
[2] The laminate according to [1], which is a laminate having at least a four-layer structure in which the layer F is present on both sides of the layer P.
[3] The laminate according to [1] or [2], wherein the root mean square roughness of the surface of the metal foil layer is 0.25 μm or more.
[4] The laminate according to any one of [1] to [3], wherein the thickness of the metal foil layer is 2 to 30 μm.
[5] The laminate according to any one of [1] to [4], wherein the non-thermoplastic polyimide is a non-thermoplastic polyimide having a glass transition temperature of 280 ° C. or higher.

[6] The laminate according to any one of [1] to [5], wherein the non-thermoplastic polyimide is a non-thermoplastic polyimide having a tensile elastic modulus of 0.2 GPa or more at 320 ° C.
[7] The laminate according to any one of [1] to [6], wherein the non-thermoplastic polyimide has an imide group density of 0.20 to 0.35.
[8] The laminate according to any one of [1] to [7], wherein the layer P has a thickness of 10 to 100 μm.
[9] The laminate according to any one of [1] to [8], wherein the tetrafluoroethylene polymer is a heat-meltable tetrafluoroethylene polymer having a melting temperature of 260 to 320 ° C.
[10] The laminate according to any one of [1] to [9], wherein the layer F has a thickness of 1 to 38 μm.

[11] When the laminate is held at 24 ° C. in an atmosphere of 50% relative humidity for 24 hours, the dielectric constant of the layer P in contact with the layer F is 2.8 or less, and the dielectric loss tangent is 0.004. The laminate according to any one of [1] to [10], which is the laminate below.
[12] When the laminate is held at 85 ° C. in an atmosphere of 85% relative humidity for 72 hours, the dielectric constant of the layer P in contact with the layer F is 2.8 or less, and the dielectric loss tangent is 0.007. The laminate according to any one of [1] to [11], which is the laminate below.
[13] A method for manufacturing a printed circuit board, wherein the metal foil layer of the laminate according to any one of [1] to [12] is etched to form a transmission circuit to obtain a printed circuit board.
[14] A printed circuit board having a layer P of non-thermoplastic polyimide, a layer F of a tetrafluoroethylene polymer existing on at least one surface of the layer P, and a transmission circuit existing on at least one surface thereof. A printed circuit board in which the water absorption rate of the layer P is less than 1.5% and the absolute value of the linear expansion coefficient is 25 ppm / ° C. or less.
[15] An antenna formed from the printed circuit board according to the above [14].

According to the present invention, a printed circuit board that is not easily affected by water and has a reduced transmission loss can be obtained. Further, a laminate having a dielectric layer having a dielectric property, heat resistance and adhesion, and a low water absorption rate, which is suitable for efficient production of such a printed circuit board, and a metal foil layer can be obtained.

The following terms have the following meanings.
The "heat-meltable polymer (resin)" means a melt-fluid polymer, and has a melt flow rate of 0.1 to 1000 g at a temperature 20 ° C. or higher higher than the melt temperature of the polymer under the condition of a load of 49 N. It means a polymer having a temperature of / 10 minutes. The "melt flow rate" means the melt mass flow rate (MFR) of the polymer defined in JIS K 7210: 1999 (ISO 1133: 1997).
The "glass transition point (Tg) of a polymer" is a value measured by analyzing a polymer by a dynamic viscoelasticity measurement (DMA) method.
The “polymer melting temperature” is the temperature corresponding to the maximum value of the melting peak measured by the differential scanning calorimetry (DSC) method.
"D50 of powder" is a volume-based cumulative 50% diameter of powder obtained by a laser diffraction / scattering method. That is, the particle size distribution is measured by a laser diffraction / scattering method, the cumulative curve is obtained with the total volume of the particle population as 100%, and the particle diameter is the point at which the cumulative volume is 50% on the cumulative curve.
"D90 of powder" is a volume-based cumulative 90% diameter of powder obtained by a laser diffraction / scattering method. That is, the particle size distribution is measured by a laser diffraction / scattering method, the cumulative curve is obtained with the total volume of the particle population as 100%, and the particle diameter is the point at which the cumulative volume is 90% on the cumulative curve.
The powders D50 and D90 are obtained by dispersing the powder in water and analyzing it by a laser diffraction / scattering method using a laser diffraction / scattering type particle size distribution measuring device (LA-920 measuring device manufactured by HORIBA, Ltd.). ..
"Liquid viscosity" is the viscosity of the liquid measured at room temperature (25 ° C.) and at a rotation speed of 30 rpm using a B-type viscometer. The measurement is repeated 3 times, and the average value of the measured values for 3 times is used.
The “ten-point average roughness of the layer” is a value specified in Annex JA of JIS B 0601: 2013.
The “root mean square roughness of the layer” is a value defined by JIS B 0601: 2013 (ISO 4287: 1997, Amd. 1: 2009).
Unless otherwise specified, "film dielectric constant and dielectric loss tangent" are measured using a split-post dielectric resonator (SPDR) at a frequency of 10 GHz in an environment of 23 ° C. ± 2 ° C. and a relative humidity of 50 ± 5%. Value. The same applies to "dielectric constant and dielectric loss tangent of layer".
The "tensile elastic modulus of the film" is a value measured at a measurement frequency of 10 Hz using a wide-area viscoelasticity measuring device.
The "unit" in an addition polymerization polymer (resin) means an atomic group based on one molecule of the monomer formed by polymerization of a monomer. The unit may be an atomic group directly formed by a polymerization reaction, or may be an atomic group in which a part of the atomic group is converted into another structure by processing a polymer. Hereinafter, the unit based on the monomer a is also simply referred to as a “monomer a unit”.
The "unit" in the co-condensation polymer (resin) means an atomic group derived from one molecule of each of the two monomers formed by polycondensation of the two monomers to be polycondensed. For example, in the non-thermoplastic polyimide of the present invention, each of the tetracarboxylic acid residue and the diamine residue is referred to as a unit.

The laminate of the present invention has a metal foil layer, a layer P of non-thermoplastic polyimide, and a layer F of a tetrafluoroethylene-based polymer, and at least one of the outermost layers is a metal foil layer. In the body, the layer F is present on at least one surface of the layer P. In the present invention, the water absorption rate of the layer P is less than 1.5%, and the absolute value of the linear expansion coefficient of the layer P is 25 ppm / ° C. or less. Hereinafter, the tetrafluoroethylene polymer is also referred to as "F polymer".
The reason why the laminate of the present invention (the same applies to the printed circuit board of the present invention) has a low water absorption rate and is excellent in dielectric properties, heat resistance, and adhesion to a metal foil layer (transmission circuit in the case of a printed circuit board). Although it is not always clear, it can be considered as follows.

The layer F is present on at least one surface of the layer P in the present invention. Since the F polymer has excellent dielectric properties and heat resistance and a low water absorption rate, it is considered that this configuration improves the dielectric properties, heat resistance and water absorption rate of the laminate. On the other hand, the F polymer generally has a large coefficient of linear expansion, and it is presumed that the dimensional stability and adhesion of the laminate are likely to be lowered. On the other hand, the layer P in the present invention is a layer having a linear expansion coefficient in a predetermined range and containing a non-thermoplastic polyimide. The non-thermoplastic polyimide is a polyimide having a non-thermoplastic block site and having a low imide group density, which is also called a modified polyimide. It is considered that such polyimide highly interacted with the F polymer to improve the dimensional stability and adhesion of the laminate. As a result, it is considered that the peeling of the metal foil layer in the high temperature process such as the solder float process was suppressed, and the swelling of the laminated body was suppressed.

The "non-thermoplastic polyimide" is a polyimide that does not soften or show adhesiveness even when heated, and has a storage elastic modulus of 1 at 30 ° C. as measured using a dynamic viscoelasticity measuring device (DMA). It means a polyimide having a storage elastic modulus of 3.0 × 10 ⁸ Pa or more at 280 ° C. and 0.0 × 10 ⁹ Pa or more. The "non-thermoplastic polyimide" is a molded product (film, etc.) formed by drying a solution (solution of a polyimide precursor) obtained by combining monomers and solution-polymerizing it, and further imidizing it at 450 ° C. for 1 minute. It is also a polyimide that retains its shape when heated.
Further, the "thermoplastic polyimide", a polyimide having a glass transition temperature (Tg) can be confirmed, it was measured using a DMA, and a storage modulus 1.0 × ¹⁰ 9 Pa or more at 30 ° C., 280 storage modulus at ℃ means a polyimide is less than 3.0 × ¹⁰ 8 Pa. "Thermoplastic polyimide" is obtained by drying a solution (solution of a polyimide precursor) obtained by combining monomers and performing solution polymerization, and further heating a molded product (film or the like) formed by imidization at 450 ° C. for 1 minute. It is also a polyimide that deforms or fuses due to wrinkles or elongation.

The laminate of the present invention is a laminate (metal-clad laminate) having a metal foil layer, a layer P, and a layer F, and at least one of the outermost layers is a metal foil layer.
In the laminate of the present invention, the layer F may be present only on one side of the layer P, or the layer F may be present on both sides of the layer P. In the former case, the layer F may be present only on the surface of the layer P on the metal foil layer side, and the layer F is present only on the opposite surface (outermost surface) of the layer P on the metal foil layer side. You may be.

The laminated body of the present invention includes a metal foil layer, a layer F and a layer P in this order, a metal foil layer, a layer P and a layer F in this order, a metal foil layer, a layer F, a layer P and the like. An embodiment having layers F in this order can be mentioned. If the layer F is provided on the outermost surface, a laminate having a lower water absorption rate can be obtained, and if the layer F is provided between the metal foil layer and the layer P, heat resistance (particularly, solder float resistance) and dielectric properties are improved. A better laminate can be obtained. As the aspect of the laminated body of the present invention, the last aspect in which the layers F are provided on both sides of the layer P is preferable.
Further, the laminate of the present invention may be a double-sided metal-clad laminate having metal foil layers on both sides. Examples of the double-sided metal-clad laminate include a mode in which the metal foil layer, the layer F, the layer P and the metal foil layer are provided in this order, and a mode in which the metal foil layer, the layer F, the layer P, the layer F and the metal foil layer are provided in this order. Be done. The latter aspect is preferable as the double-sided metal-clad laminate having layers F on both sides of the layer P.
In the laminate of the present invention, it is preferable that at least a part of the layer P and at least a part of the layer F are in contact with each other, and it is preferable that the entire one side of the layer P and the entire one side of the layer F are in contact with each other. Especially preferable. In this case, not only the adhesion between the layer P and the layer F is further improved, but also the water absorption rate tends to be remarkably lowered.

In the present invention, the ratio of the thickness of the layer P to the thickness of the layer F is preferably 1 or more. The ratio is preferably 2 or more, more preferably 4 or more, and particularly preferably 8 or more. The ratio is preferably 100 or less, more preferably 50 or less, more preferably 35 or less, and particularly preferably 20 or less. In this case, it is easy to balance the suppression of dimensional change (warp, etc.) and interfacial peeling of the laminated body due to heating, the water absorption of the laminated body, and the dielectric property of the laminated body. When the laminate of the present invention contains a plurality of layers F as in the last aspect, the thickness of the layers F means the thickness of each layer F.
The thickness of the metal foil layer in the present invention is preferably 2 to 30 μm, particularly preferably 3 to 25 μm.
The ratio of the thickness of the layer F to the thickness of the metal foil layer is preferably 0.5 or more, and preferably 1 or more. The ratio is preferably 10 or less, more preferably 5 or less. In this case, it is easy to balance the suppression of dimensional change (warp, etc.) and interfacial peeling of the laminated body due to heating, the water absorption of the laminated body, and the dielectric property of the laminated body.

Examples of the material of the metal foil in the present invention include copper, copper alloy, stainless steel, nickel, nickel alloy (including 42 alloy), aluminum, aluminum alloy, titanium, titanium alloy and the like. As the material of the metal foil, copper and a copper alloy are preferable.
Examples of the copper foil include rolled copper foil and electrolytic copper foil.
A rust preventive layer (oxide film such as chromate), a heat resistant layer, or the like may be formed on the surface of the metal foil.
The surface of the metal foil layer may be treated with a silane coupling agent. In this case, the entire surface of the metal foil may be treated, or a part of the surface of the metal foil may be treated.
The ten-point average roughness of the surface of the metal foil layer (hereinafter, also referred to as “Rzjis”) is preferably 0.2 to 2.5 μm. In this case, the adhesion between the metal foil layer and the layer F or the layer P is improved, and a laminated body having excellent dielectric properties can be easily obtained.

The root mean square roughness (hereinafter, also referred to as “Rq”) of the surface of the metal foil layer is preferably 0.05 μm or more, more preferably 0.10 μm or more, still more preferably 0.12 μm or more. Rq is preferably 0.25 μm or less, more preferably 0.20 μm or less.
When the Rq of the metal foil layer is within the range, the adhesion between the metal foil layer and each layer is good, the effective conductivity at the interface is high, and the transmission loss is likely to be reduced.
The effective conductivity of the interface is the conductivity at the contact interface between the resin of the layer and the metal foil layer. The higher the frequency of the electric signal, the more the electric signal flows near the interface. Therefore, the higher the effective conductivity of the interface, the smaller the transmission loss.
The effective conductivity of the interface is determined by the following Groisse approximation formula.

The symbols in the formula have the following meanings.
σ _c : Effective conductivity σ: Conductivity of the conductor s: Skin thickness through which the current flows h: Squared average square root roughness of the surface of the conductor Note that the conductivity of the conductor is based on the metal type of the metal foil and is the surface of the conductor. Since the squared average square root roughness of is determined based on the Rq of the metal foil layer and the skin thickness is determined based on the frequency, the effective conductivity of the interface increases as the Rq of the metal foil layer decreases.

Further, the metal foil layer may be a metal foil with a carrier including two or more layers of metal foil. The metal foil with a carrier includes a carrier copper foil (thickness: 10 to 35 μm) and an ultrathin copper foil (thickness: 2 to 5 μm) laminated on the carrier copper foil via a release layer. Copper foil can be mentioned.
By sequentially laminating the layers on the ultrathin copper foil side of the copper foil with a carrier and then peeling off only the carrier copper foil, a laminate having the ultrathin copper foil can be easily formed. By using this laminate, it is possible to form a fine pattern by using an ultrathin copper foil layer as a plating seed layer by an MSAP (Modified Semi-Additive) process.
From the viewpoint of heat resistance, the release layer is preferably a metal layer containing nickel or chromium or a multilayer metal layer in which the metal layers are laminated. With such a peeling layer, the carrier metal foil can be easily peeled from the ultrathin metal foil even after a step of 300 ° C. or higher.
Specific examples of the metal foil with a carrier include the trade name "FUTF-5DAF-2" manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.

The layer P in the present invention contains a non-thermoplastic polyimide. The layer P may contain other components as long as it does not interfere with the effects of the present invention. Specific examples of other components include powders of F polymers such as PTFE and PFA from the viewpoint of further improving the dielectric properties, and glass chopped strands, aramid chopped strands, and polybenzo from the viewpoint of reducing the coefficient of linear expansion. Examples thereof include fillers such as oxazole chopped strands, silica, alumina, and magnesium oxide.
The layer P preferably contains non-thermoplastic polyimide as a main component, and preferably contains 80 to 100% by mass of non-thermoplastic polyimide.

The water absorption rate of the layer P is less than 1.5%, preferably 1.2% or less. The water absorption rate of the layer P is preferably more than 0%.
The absolute value of the coefficient of linear expansion of the layer P is 25 ppm / ° C. or lower, preferably 22 ppm / ° C. or lower, more preferably 15 ppm / ° C. or lower, and particularly preferably 10 ppm / ° C. or lower. The absolute value of the coefficient of linear expansion coefficient of layer P is preferably more than 0 ppm / ° C.
The layer P is preferably formed of a non-thermoplastic polyimide film (hereinafter, also referred to as "mPI film"). The physical properties of the layer P in this case are regarded as those of the original mPI film.
The coefficient of linear expansion coefficient of the layer P is 10 ° C. using a thermomechanical analyzer, using a non-thermoplastic polyimide film used for forming the layer P, with a measurement load of 29.4 mN and a measurement atmosphere of a nitrogen atmosphere. Linear expansion coefficient when the temperature is raised from 0 ° C to 400 ° C at 1 / min, cooled to 10 ° C at 40 ° C / min, and further raised from 10 ° C to 200 ° C at 10 ° C / min. It was requested as.
The surface of the mPI film may be surface-treated with a silane coupling agent or the like, or may be surface-modified by corona treatment, plasma treatment or the like. Further, the surface of the mPI film may be roughened or annealed.

In particular, if the surface of the mPI film is plasma-treated, it can be laminated with the layer F at a lower temperature, and the deformation of the layer P can be more easily reduced. The plasma treatment is preferably atmospheric pressure plasma treatment or vacuum plasma treatment.
The vacuum plasma treatment is preferably a glow discharge treatment (so-called low temperature plasma treatment) in which continuous discharge is performed at a gas pressure of 0.1 to 1330 Pa (preferably 1 to 266 Pa). In this case, if a power of 10 W to 100 kW is applied between the discharge electrodes at a frequency of 10 kHz to 2 GHz, stable glow discharge processing can be performed.
The discharge power density of the vacuum plasma treatment is preferably 5 to 400 W · min / m ² from the viewpoint of adjusting the wetting tension on the surface of the mPI film.
Examples of the gas used include helium gas, neon gas, argon gas, nitrogen gas, oxygen gas, carbon dioxide gas, hydrogen gas, air, and water vapor. As the gas, one type may be used alone, or two or more types may be mixed and used. As the gas, argon gas, nitrogen gas, hydrogen gas, and a mixed gas thereof are preferable from the viewpoint of further improving the interlayer adhesion strength.
The time of the vacuum plasma treatment is preferably 5 to 60 seconds from the viewpoint of further improving the interlayer adhesion strength.

In the atmospheric pressure plasma treatment, the glow discharge treatment is preferable under 0.8 to 1.2 pressure and in an atmosphere of an inert gas (argon gas, nitrogen gas, helium gas, etc.). A trace amount of active gas (oxygen gas, hydrogen gas, carbon dioxide gas, ethylene, tetrafluoroethylene, etc.) may be mixed with the inert gas.
As the gas used, argon gas, nitrogen gas, hydrogen gas, and a mixed gas thereof are preferable from the viewpoint of further improving the interlayer adhesion strength.
The voltage, the frequency of the power source, and the plasma processing time in the atmospheric pressure plasma processing are usually 1 to 10 kV, 1 to 20 kHz, and 0.1 seconds to 10 minutes in this order.
The discharge power density of the atmospheric pressure plasma treatment is preferably 5 to 400 W / min / m ² .

The non-thermoplastic polyimide in the present invention preferably contains a non-thermoplastic block moiety. The non-thermoplastic block site retains its shape when a polyimide precursor obtained by solution polymerization of only the monomers constituting the block site is evaluated in the same manner as the above-mentioned definition method of non-thermoplastic polyimide. It means a block site formed from a combination of monomers that forms the polyimide to be formed. On the other hand, the thermoplastic block site has a shape when evaluated in the same manner as the above-mentioned definition method of non-thermoplastic polyimide from a polyimide precursor obtained by solution-polymerizing only the monomers constituting the block site. It means a block site formed from a combination of monomers that forms a non-retained polyimide.
When determining whether the block portion is thermoplastic or non-thermoplastic, if the block portion is rigid, the fragments may be collected and heated to determine from the state of holding the shape.

The glass transition temperature of the non-thermoplastic polyimide in the present invention is preferably 280 ° C. or higher, more preferably 290 ° C. or higher. The glass transition temperature is preferably 450 ° C. or lower, and particularly preferably 400 ° C. or lower. In this case, the layer F and the layer P can be laminated at a lower temperature, and a laminated body having more excellent dimensional stability can be easily obtained.

The tensile elastic modulus of the non-thermoplastic polyimide in the present invention at 320 ° C. is preferably 0.2 GPa or more, preferably 0.4 GPa or more. The tensile elastic modulus is preferably 10 GPa or less, and more preferably 5 GPa or less.
The laminate in this case is excellent in handleability even when exposed to heating and cooling operations for processing it. That is, when the tensile elastic modulus of the non-thermoplastic polyimide is equal to or higher than the lower limit, the shrinkage of the layer F during heating and cooling is effectively alleviated by the elasticity of the layer P, and wrinkles are less likely to occur in the laminated body. It is easy to improve the physical properties (surface smoothness, etc.) of the processed product. This tendency becomes remarkable when the content of the F polymer in the layer F and the thickness of the layer F are large. Further, when the tensile elastic modulus of the non-thermoplastic polyimide is not more than such an upper limit, the flexibility of the laminated body is more likely to be excellent.

The imide group density of the non-thermoplastic polyimide in the present invention is preferably 0.20 to 0.35. When the imide group density is the upper limit, the water absorption rate of the non-thermoplastic polyimide becomes lower, and it is easier to suppress the change in the dielectric property of the laminate. When the imide group density is the lower limit, it functions as a polar group, and not only the adhesion between the layer P and the layer F is further improved, but also the water absorption rate is likely to be significantly reduced.
Further, if the imide group density of the non-thermoplastic polyimide is within such a range, wrinkles in the processing of the laminated body tend to be more difficult. This tendency becomes remarkable when the glass transition temperature of the non-thermoplastic polyimide is low.
The imide group density is a value obtained by dividing the molecular weight per unit of the imide group portion (140.1) by the molecular weight per unit of the polyimide in the polyimide obtained by imidizing the polyimide precursor. For example, a polyimide precursor consisting of two components, 1 mol of pyromellitic dianhydride (molecular weight: 218.1) and 1 mol of 3,4'-oxydianiline (molecular weight: 200.2), was imidized. The imide group density of polyimide (molecular weight per unit: 382.2) is 0.37, which is the value obtained by dividing 140.1 by 382.2.

The non-thermal polyimide in the present invention is 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, paraphenylenediamine, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2'. -Dimethyl-4,4'-diaminobiphenyl, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-(1,3-phenylenediisopropyridene) bisaniline, 2,2'-n-propyl-4,4'-diaminobiphenyl and Multiple aromatic diamines selected from the group consisting of 4-aminophenyl-4'-aminobenzoate, pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2 , 3,3', 4'-biphenyltetracarboxylic dianhydride, 2,3,2', 3'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3' , 4,4'-Benzenetetracarboxylic dianhydride, 1,4-phenylenebis (trimellitic acid monoester) dianhydride, p-phenylenebis (tritate anhydride), 1,4-phenylenebis (trimerit) Acid monoester) Selected from the group consisting of dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, and 2,3,6,7-naphthalenetetracarboxylic dianhydride. It preferably contains a unit formed from a plurality of aromatic acid dianhydrides. In this case, not only the non-thermoplasticity of the non-thermoplastic polyimide is improved and the adhesion between the layer P and the layer F is further improved, but also the water absorption rate tends to be remarkably lowered.
The non-thermoplastic polyimide preferably contains 80 mol% or more of the above units with respect to all the units. The upper limit is 100 mol%.

In addition, non-thermoplastic polyimides include metaphenylenediamine, 1,5-diaminonaphthalene, benzidine, 3,3'-dimethoxybenzidine, paraxylylene diamine, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4. , 4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 1,4-bis (3-methyl-5-aminophenyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4- Bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-bis (trifluoromethyl) benzidine, 3,3'-bis (trifluoromethyl) ) Other diamines such as benzidine and 2,2-bis (4-aminophenyl) hexafluoropropane may be used as the unit monomer component. These other diamines may be used alone or in combination of two or more.

In addition, non-thermoplastic polyimides include pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, pyridine-2,3,5,6-tetracarboxylic acid, 4,4'-oxydiphthalic acid, 3,3. ', 4,4'-biphenyltetracarboxylic acid, 2,3', 3,4'-biphenyltetracarboxylic acid, 3,3', 4,4'-benzophenonetetracarboxylic acid, 5,5'-[1- Other tetracarboxylic acids such as methyl-1,1-ethanediylbis (1,4-phenylene) bisoxy] bis (isobenzofuran-1,3-dione), 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride Alternatively, a derivative thereof may be used as a unit monomer component. These other tetracarboxylic acids or derivatives thereof may be used alone or in combination of two or more.

The synthesis of the polyimide precursor (polyamic acid) in producing a non-thermoplastic polyimide is preferably carried out in the presence of a solvent. Specific examples of the solvent include dimethyl sulfoxide, diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, N. -Vinyl-2-pyrrolidone, phenol, cresol, xylenol, phenol halide, catechol, hexamethylphospholamide can be mentioned.
The polyimide precursor is preferably prepared in a solution containing the polyimide precursor as a solid content of 5 to 40% by weight. The viscosity of the solution in this case is preferably 100 to 1000 Pa · s. In addition, a part of the polyimide precursor may be imidized in the solution.

The thickness of the layer P in the present invention is preferably 10 to 100 μm.
The dielectric loss tangent of the layer P in the present invention at 10 GHz is preferably 0.008 or less. The dielectric loss tangent is preferably more than 0.

The layer F in the present invention contains an F polymer.
The layer F may contain other components as long as it does not interfere with the effects of the present invention, but it is preferable that the layer F contains the F polymer as a main component, and preferably contains 80 to 100% by mass of the F polymer.
The layer F is preferably a layer formed by melting the F polymer (a layer of a melt-molded product of the F polymer). In this case, since the layer F becomes non-porous, the heat insulating effect at the time of heating in the solder float step is further improved, and the etching resistance is also likely to be improved.
The F polymer is preferably a heat-meltable F polymer, and F has a melting temperature of 260 to 320 ° C. from the viewpoint that not only the heat resistance and interlayer adhesion of the laminate are further improved, but also the water absorption rate is likely to be significantly reduced. Polymers are more preferred.

The F polymer in the present invention is a polymer having a unit (TFE unit) based on tetrafluoroethylene (hereinafter, also referred to as "TFE"). The F polymer may be a homopolymer of TFE, or may be a copolymer of TFE and a comonomer copolymerizable with TFE. The F polymer preferably has 90 to 100 mol% of TFE units with respect to all the units constituting the polymer. The fluorine content of the F polymer is preferably 70 to 76% by mass, more preferably 72 to 76% by mass.
Examples of the F polymer include polytetrafluoroethylene (PTFE), a copolymer of TFE and ethylene (ETFE), a copolymer of TFE and propylene, and a copolymer of TFE and perfluoro (alkyl vinyl ether) (hereinafter, also referred to as "PAVE"). (PFA), a copolymer of TFE and hexafluoropropylene (hereinafter, also referred to as "HFP") (FEP), a copolymer of TFE and fluoroalkylethylene (hereinafter, also referred to as "FAE"), TFE and chlorotrifluoro. Examples include copolymers with ethylene. The copolymer may have a unit based on another comonomer.

Preferable specific examples of the F polymer include low molecular weight PTFE, modified PTFE, FEP and PFA. The low molecular weight PTFE or modified PTFE shall also include a copolymer of TFE and a trace amount of comonomer (HFP, PAVE, FAE, etc.).
The F polymer is preferably an F polymer having a TFE unit and a functional group. The functional group is preferably a carbonyl group-containing group, a hydroxy group, an epoxy group, an amino group or an isocyanate group. The functional group may be contained in a unit in the F polymer, or may be contained in the terminal group of the main chain of the polymer. Examples of the latter polymer include polymers having a functional group as a terminal group derived from a polymerization initiator, a chain transfer agent, or the like. Further, an F polymer having a functional group obtained by subjecting the surface of the F polymer layer to plasma treatment or ionization line treatment can also be mentioned.
The F polymer having a functional group is preferably an F polymer having a TFE unit and a unit having a functional group. As the unit having a functional group, a unit based on a monomer having a carbonyl group-containing group, a hydroxy group, an epoxy group, an amino group or an isocyanate group is preferable.

As the monomer having a carbonyl group-containing group, a cyclic monomer having an acid anhydride residue, a monomer having a carboxy group, a vinyl ester and a (meth) acrylate are preferable, and a cyclic monomer having an acid anhydride residue is more preferable. In particular, itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride (also known as hymic anhydride) and maleic anhydride are preferable.
Preferable specific examples of the F polymer having a functional group include an F polymer having a TFE unit, an HFP unit, a PAVE unit or a FAE unit, and a unit having a functional group.
As PAVE, CF ₂ = CFOCF ₃ , CF ₂ = CFOCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFO (CF ₂ ) ₈ F Can be mentioned.
As FAE, CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ = CF (CF ₂ ) ₃ H, CH ₂ = CF (CF ₂ ) ₄ H can be mentioned.
Such an F polymer has 90 to 99 mol% of TFE units, 0.5 to 9.97 mol% of HFP units, PAVE units or FAE units, and 0 units having a functional group with respect to all the units constituting the polymer. It is preferable to have 0.01 to 3 mol%, respectively. Specific examples of such F polymers include the polymers described in International Publication No. 2018/16644.

The thickness of layer F is preferably 1 to 38 μm or less. The thickness is more preferably 2 μm or more. The thickness is preferably 35 μm or less, more preferably 30 μm or less. In this case, the heat resistance of the laminate is likely to be improved while suppressing dimensional changes (warpage, etc.) and interfacial peeling of the laminate during heating. Further, when the thickness of the layer F is 1 μm or more, the transmission loss in the high frequency region of the printed circuit board is significantly improved regardless of the configuration of the layer P. When the thickness of the layer F is not more than the upper limit value, it is easy to suppress dimensional changes (warpage, etc.) and interfacial peeling of the laminated body due to heating.

As a specific configuration of the laminated body of the present invention, at least one of the outermost layers is a laminated body which is a copper foil layer, and layers F are present on both sides of the layer P, and at least a part of each layer F. An example is a laminate in which at least a part of the layer P is in contact with the layer P. More specifically, a laminate having a structure of a copper foil layer / layer F / layer P / layer F, and a laminate having a structure of a copper foil layer / layer F / layer P / layer F / copper foil layer. Can be mentioned.
In the above configuration, the thickness of the copper foil layer is 3 to 25 μm, the thickness of the layer F is 2 to 30 μm independently, the thickness of the layer P is 10 to 100 μm, and the thickness of the copper foil layer. The ratio of the thickness of the layer F to the thickness of the layer F is preferably 0.5 to 5, and the ratio of the thickness of the layer P to the thickness of the layer F is preferably 1 to 50, respectively.
Further, the layer P is preferably a layer formed from an mPI film whose surface is plasma-treated.
Further, the layer F is preferably a layer of a heat-meltable F polymer. The layer F may also be a layer formed from a layer of F polymer whose surface is plasma-treated before lamination.

In the present invention, the layer P in which the layer F is present on at least one surface (that is, the layer P in which one side is in contact with the layer F or the layer P in which both sides are in contact with the layer F) is in an environment of normal temperature and humidity. It has excellent long-term sustainability of electrical characteristics underneath.
As the laminate of the present invention, a laminate in which the dielectric constant of the layer P in contact with the layer F is 2.8 or less when the laminate is held at 24 ° C. and an atmosphere having a relative humidity of 50% for 24 hours is preferable. A laminate having a thickness of 2.7 or less is more preferable. The lower limit of the dielectric constant is preferably 2.
Further, when the laminate of the present invention is held at 24 ° C. in an atmosphere of 50% relative humidity for 24 hours, the dielectric loss tangent of the layer P in contact with the layer F is 0.004 or less, and the laminate is preferably 0. A laminate having a value of .003 or less is more preferable. The lower limit of the dielectric loss tangent is preferably 0.0001.

In addition, the layer P in the present invention is also excellent in long-term sustainability of electrical characteristics in a hot and humid environment. As the laminate of the present invention, a laminate in which the dielectric constant of the layer P in contact with the layer F is 2.8 or less when the laminate is held in an atmosphere of 85 ° C. and a relative humidity of 85% for 72 hours is preferable. A laminate having a thickness of 2.7 or less is more preferable. The lower limit of the dielectric constant is preferably 2.
Further, when the laminate of the present invention is held in an atmosphere of 85 ° C. and a relative humidity of 85% for 72 hours, the dielectric loss tangent of the layer P in contact with the layer F is 0.007 or less, and the laminate is preferably 0. A laminate having a value of .006 or less is more preferable. The lower limit of the dielectric loss tangent is preferably 0.0001.

In the laminate of the present invention, the resin-attached metal foil having the metal foil layer and the layer F and the mPI film to be the layer P are fused by the hot press method with the resin-attached metal foil layer F and the mPI film facing each other. It is preferable to wear it for production.
At this time, the tensile elastic modulus of the non-thermoplastic polyimide in the mPI film at 320 ° C. is preferably 0.2 GPa or more, preferably 0.4 GPa or more. The tensile elastic modulus is preferably 10 GPa or less, and more preferably 5 GPa or less. When the tensile elastic modulus of the non-thermoplastic polyimide is at least such a lower limit, the shrinkage of the layer F during cooling after hot pressing is likely to be effectively relaxed by the elasticity of the layer P. As a result, wrinkles are less likely to occur in the laminated body, and it is easy to obtain a laminated body having better physical properties such as surface smoothness. This tendency becomes remarkable when the imide group density or the glass transition temperature of the non-thermoplastic polyimide in the mPI film is low. Further, when the tensile elastic modulus of the non-thermoplastic polyimide is not more than such an upper limit, the flexibility of the laminated body is more likely to be excellent.

Examples of the method for producing the metal foil with resin include a method of applying a powder dispersion of F polymer to the surface of the metal foil. Specifically, a powder containing an F polymer (hereinafter, also referred to as "F powder"), a solvent, and a powder dispersion containing a dispersant are applied to the surface of the metal foil, and a temperature range of 100 to 300 ° C. is applied. (Hereinafter, also referred to as “holding temperature”), the metal foil layer is held to remove the solvent, and the F polymer is fired in a temperature range exceeding the above temperature range to form a layer F on the surface of the metal foil. There is a way to do it.

The F powder preferably contains the F polymer as a main component, and preferably contains 80 to 100% by mass of the F polymer.
The D50 of the F powder is preferably 0.05 to 6.0 μm, more preferably 0.2 to 3.0 μm.
The D90 of the F powder is preferably 0.3 to 8 μm, more preferably 0.8 to 5 μm.
When D50 or D90 of the F powder is in the above range, the fluidity and dispersibility of the F powder are improved, and the dielectric properties and heat resistance of the layer F are more likely to be improved.
The solvent is preferably a compound that does not volatilize instantaneously but volatilizes when it is held at the above-mentioned holding temperature, and more preferably a compound having a boiling point of 125 to 250 ° C.
As the solvent, 1-butanol, 1-methoxy-2-propanol, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, N-methyl-2-pyrrolidone, γ- Butyrolactone, cyclohexanone and cyclopentanone are preferred.

The dispersant is a compound having a hydrophilic group and a hydrophobic group, and is preferably a fluorine-based dispersant, a silicone-based dispersant or an acetylene-based dispersant, and more preferably a fluorine-based dispersant. The dispersant is preferably nonionic.
As the fluorine-based dispersant, fluoromonool, fluoropolyol, fluorosilicone and fluoropolyether are preferable.
The fluoropolyol is preferably a copolymer of a fluoro (meth) acrylate and a (meth) acrylate having a hydroxyl group or a polyoxyalkylene group, and a (meth) acrylate having a polyfluoroalkyl group or a polyfluoroalkenyl group and a polyoxyalkylene monool group. Copolymers with (meth) acrylates have are more preferred.
As the fluorosilicone, polyorganosiloxane having a CF bond in a part of the side chain is preferable.
As the fluoropolyether, a compound in which a part of hydrogen atoms of the polyoxyalkylene alkyl ether is replaced with a fluorine atom is preferable.

The powder dispersion liquid may contain components other than the F powder, the solvent and the dispersant. Other ingredients include thixotropic agents, defoamers, inorganic fillers, reactive alkoxysilanes, dehydrating agents, plasticizers, weather resistant agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, etc. Examples thereof include colorants, conductive agents, mold release agents, surface treatment agents, viscosity modifiers, and flame retardants. Further, the powder dispersion liquid may contain a resin component (thermosetting resin, thermoplastic resin, etc.) other than the F polymer.
The ratio of F powder in the powder dispersion is preferably 5 to 60% by mass.
The ratio of the dispersant in the powder dispersion is preferably 0.1 to 30% by mass.
The ratio of the solvent in the powder dispersion is preferably 15 to 65% by mass.

The coating methods include spray method, roll coating method, spin coating method, gravure coating method, micro gravure coating method, gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, fountain Mayer bar method, and slot die coating. The law can be mentioned.
After the coating, before the metal foil with the wet film is subjected to the holding temperature, the state of the wet film may be adjusted by heating to a temperature lower than the above temperature range. The adjustment should be at a temperature at which the solvent does not completely volatilize.

When the powder dispersion is applied to the surface of the metal foil and kept at the holding temperature, the solvent volatilizes and the dispersant decomposes, and a highly smooth film in which the F powder is densely packed is formed. At this time, it is considered that the dispersant is easily repelled by the F powder and easily flows to the surface. That is, it is considered that this retention forms a state in which the dispersant is segregated on the surface.
The holding atmosphere may be in any state under normal pressure or reduced pressure. Further, the atmosphere for holding may be any of an oxidizing gas atmosphere such as oxygen gas, a reducing gas atmosphere such as hydrogen gas, and an inert gas atmosphere such as helium gas, neon gas, argon gas, and nitrogen gas.
The holding temperature is preferably in the temperature range of 200 to 300 ° C. In this range, the solvent is removed, the partial decomposition and flow of the dispersant proceed effectively, and the dispersant is more likely to be surface segregated.
The time for holding at the holding temperature is preferably 0.1 to 10 minutes, and particularly preferably 0.5 to 5 minutes.

In the production of the metal foil with resin, it is preferable to further fire the F polymer in a temperature region above the holding temperature (hereinafter, also referred to as “firing temperature”) to form the layer F on the surface of the metal foil.
In the firing, the F powder is densely packed and the F polymer is fused in a state where the dispersant is effectively surface segregated, so that the layer F having excellent smoothness and fusion property is formed.
If the powder dispersion contains a thermosetting resin, a layer F composed of a mixture of the F polymer and the soluble resin is formed, and if the powder dispersion contains the thermosetting resin, the F polymer and the thermosetting resin are cured. A layer F made of an object is formed.
Examples of the firing method include a method using an oven, a method using a ventilation drying furnace, a method of irradiating heat rays such as infrared rays, and the like. In order to improve the smoothness of the surface of the layer F, pressure may be applied with a heating plate, a heating roll or the like. As a firing method, a method of irradiating far infrared rays is preferable because it can be fired in a short time and the far infrared ray furnace is relatively compact. In firing, infrared heating and hot air heating may be combined.

The atmosphere in firing may be either under normal pressure or under reduced pressure. Further, the atmosphere in firing may be any of an oxidizing gas atmosphere such as oxygen gas, a reducing gas atmosphere such as hydrogen gas, and an inert gas atmosphere such as helium gas, neon gas, argon gas, and nitrogen gas. It is preferable to have an active gas atmosphere.
The atmosphere in the firing is preferably an atmosphere composed of an inert gas and having a low oxygen gas concentration, and preferably an atmosphere composed of nitrogen gas and having an oxygen gas concentration (volume basis) of 300 ppm or less.
The firing temperature is preferably more than 300 ° C, particularly preferably 330 to 380 ° C. In this case, the F polymer is more likely to form a dense layer F.
The time for holding at the firing temperature is preferably 30 seconds to 5 minutes.

In the production of the resin-attached metal foil, the surface of the obtained resin-attached metal foil is surface-treated in order to control the coefficient of linear expansion of the layer F and further improve the fusion property of the layer F. May be good.
Examples of the surface treatment include annealing treatment, corona discharge treatment, atmospheric pressure plasma treatment, vacuum plasma treatment, UV ozone treatment, excimer treatment, chemical etching, silane coupling treatment, and fine roughening treatment.
The temperature in the annealing treatment is preferably 80 to 190 ° C. The pressure in the annealing treatment is preferably 0.001 to 0.030 MPa. The annealing treatment time is preferably 10 to 300 minutes.
Examples of the plasma irradiation device in plasma processing include a high frequency induction method, a capacitively coupled electrode method, a corona discharge electrode-plasma jet method, a parallel plate type, a remote plasma type, an atmospheric pressure plasma type, and an ICP type high density plasma type. ..
Examples of the gas used for the plasma treatment include argon gas, a mixed gas of hydrogen gas and nitrogen gas, and a mixed gas of hydrogen gas, nitrogen gas and argon gas. In this case, by adjusting the surface roughness of the layer F, fine irregularities are likely to be formed.

The mPI film is preferably produced by cyclizing a solution of a polyimide precursor (polyamic acid) to obtain a gel film, drying the gel film, and further heat-treating the gel film. The imidization of the polyamic acid proceeds by drying and heat treatment.
As a method in the cyclization reaction, a method of casting a solution into a film and thermally cyclizing it to obtain a gel film (thermal ring closure method), or a method of mixing a catalyst and a dehydrating agent with the solution and chemically ringing the solution. A method of obtaining a gel film by a chemical reaction (chemical ring closure method) can be adopted.
Examples of the catalyst include trimethylamine, triethylenediamine, dimethylaniline, isoquinoline, pyridine and β-picoline.
Examples of the dehydrating agent include acetic anhydride, propionic anhydride, butyric anhydride, and benzoic anhydride.
The amount of the catalyst and the dehydrating agent used is preferably 1.5 to 10 mol, respectively, with respect to 1 mol of the amide group (or carboxyl group) of the polyamic acid.

The obtained gel film is dried and heat-treated.
The temperature in the drying treatment is preferably 220 to 300 ° C.
Further, in the drying, the drying temperature unevenness is preferably set to 20 ° C. or less from the viewpoint of suppressing the drying temperature unevenness in the film width direction. Further, the gel film after the drying treatment may be subjected to a stretching treatment.
The temperature in the heat treatment is more preferably 300 to 550 ° C.
The mPI film may be further subjected to surface treatment such as annealing treatment, corona treatment, plasma treatment, roughening treatment, and silane coupling agent treatment.

The press temperature in the hot press for laminating the metal foil with resin and the mPI film is preferably 300 ° C. to 350 ° C., more preferably 310 ° C. to 330 ° C. In this range, the layer F and the mPI film can be firmly fused while suppressing thermal deformation of the mPI film.
The degree of vacuum in the hot press is preferably 20 kPa or less. In this range, it is possible to suppress the mixing of air bubbles at the interfaces of the metal foil layer, the layer F, and the layer P in the laminated body and deterioration due to oxidation.
Further, during hot pressing, it is preferable to raise the temperature after reaching the above vacuum degree. In this case, since the layer F can be pressure-bonded in a state before it is softened, that is, in a state before a certain degree of fluidity and adhesion is generated, the generation of air bubbles can be prevented.
The press pressure in the hot press is preferably 0.2 to 10 MPa. In this range, the layer F and the mPI film can be firmly fused while suppressing the damage of the PI film.

The laminate of the present invention is a metal-clad laminate having layers F and P, which is excellent in physical properties such as electrical characteristics, chemical resistance (etching resistance), and heat resistance, and is a flexible printed circuit board or a rigid printed circuit board. Can be used as a material.
A method of etching the metal foil layer of the laminate of the present invention to process it into a conductor circuit (transmission circuit) having a predetermined pattern, or an electrolytic plating method (semi-additive method (SAP method)) of the metal foil layer of the laminate of the present invention. ), Modified semi-additive method (MSAP method), etc.), a printed circuit board can be manufactured from the laminate of the present invention by a method of processing into a transmission circuit.

The printed circuit board of the present invention is a printed circuit board having a layer P, a layer F existing on at least one surface of the layer P, and a transmission circuit existing on at least one surface thereof, and is a printed circuit board having water absorption of the layer P. The rate is less than 1.5%, and the absolute value of the coefficient of linear expansion of the layer P is 25 ppm / ° C. or less.
The configuration, the types of layers P and F, etc. in the printed circuit board of the present invention are the same as those in the laminate of the present invention, including a suitable range.
The structure of the printed circuit board of the present invention includes, for example, a transmission circuit / layer F / layer P configuration, a transmission circuit / layer F / layer P / layer F configuration, and a transmission circuit / layer F / layer P / layer F / transmission. A circuit configuration can be mentioned.

In the manufacture of the printed circuit board, after forming the transmission circuit, an interlayer insulating film may be formed on the transmission circuit, and a transmission circuit may be further formed on the interlayer insulating film. The interlayer insulating film can also be formed by, for example, the powder dispersion liquid in the present invention.
In the manufacture of a printed circuit board, a solder resist may be laminated on a transmission circuit. The solder resist can be formed by the powder dispersion liquid in the present invention.
In the manufacture of the printed circuit board, a coverlay film may be laminated on the transmission circuit. The coverlay film can also be formed by the powder dispersion liquid in the present invention.
Specific embodiments of the printed circuit board include a laminated body of the present invention or a multilayer printed circuit board in which the printed circuit board of the present invention is multilayered.

A preferred embodiment of the multilayer printed circuit board includes a configuration in which the outermost layer is the layer F, and one or more of the metal foil layers, the layers F, and the layers P are provided in this order.
It is preferable that a part of the metal foil layer in such an embodiment is removed to form a transmission circuit. Further, a transmission circuit formed by removing a part of the metal foil layer may exist between the layer F and the layer P.
The multilayer printed circuit board of the above aspect has a layer F on the outermost layer and is excellent in heat resistance. Specifically, swelling and peeling of the interface are unlikely to occur even at a high temperature of 250 to 300 ° C. In particular, when a transmission circuit is formed, that is, when a layer F exposed by removing a part of the metal foil layer and another layer have a contact surface, such a tendency tends to be remarkable. It is considered that the reason is that the surface roughness of the metal foil layer is transferred to the surface of the layer F, and the surface roughness of the layer F exerts an anchor effect in contact with other layers. As a result, the respective interfaces are strongly fused without subjecting to a hydrophilization treatment such as plasma treatment, and interface swelling and interfacial peeling, particularly swelling and peeling in the outermost layer can be suppressed even during heating.

As a preferred embodiment of the multilayer printed circuit board, there is also an embodiment in which the outermost layer is the layer P, and one or more of the configurations having the metal foil layer, the layer F, and the layer P in this order are included.
It is preferable that a part of the metal foil layer in such an embodiment is removed to form a transmission circuit. Further, a transmission circuit formed by removing a part of the metal foil layer may exist between the layer F and the layer P.
The multilayer printed circuit board of the above aspect has excellent heat resistance even if it has a layer P on the outermost layer, and swelling or peeling of the interface is unlikely to occur even at a high temperature of 250 to 300 ° C. In particular, when a transmission circuit is formed, that is, when a part of the metal foil layer is removed and the exposed layer F has a contact surface with another layer, such a tendency tends to be remarkable. It is considered that the reason is that the surface roughness of the metal foil layer is transferred to the surface of the layer F, and the surface roughness of the layer F exerts an anchor effect in contact with other layers. As a result, the respective interfaces are strongly fused without subjecting to a hydrophilization treatment such as plasma treatment, and swelling or peeling of the interface, particularly swelling or peeling in the outermost layer can be suppressed even during heating.
The multilayer printed circuit board in these embodiments is useful as a printed circuit board having excellent solder float resistance.

Although the laminate of the present invention, the method for manufacturing the printed circuit board, the printed circuit board and the antenna have been described above, the present invention is not limited to the configuration of the above-described embodiment.
The laminate, the printed circuit board, and the antenna of the present invention may be added with any other configuration or may be replaced with any configuration exhibiting the same function in the configuration of the above-described embodiment.
In addition, the method for manufacturing a printed circuit board of the present invention may be added to any other step in the configuration of the above-described embodiment, or may be replaced with any step that exhibits the same function.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.
Abbreviations for monomers and solvents have the following meanings.
BPDA: 3,3', 4,4'-biphenyltetracarboxylic dianhydride ODPA: 4,4'-oxydiphthalic anhydride PMDA: pyromellitic acid dianhydride PBTA: p-phenylenebis (trimeritate anhydride)
PDA: Paraphenylenediamine BAPP: 2,2'-bis [4- (4-aminophenoxy) phenyl] Propyl BAPB: 4,4'-bis (4-aminophenoxy) biphenyl PPBA: 4,4'-(1, 3-Phenylisopropylidene) Bisaniline m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis (4-aminophenoxy) benzene TFE: Tetrafluoroethylene PPVE: Perfluoro Propylvinyl ether NAH: 5-norbornene-2,3-dicarboxylic acid anhydride (hymicic anhydride)
NMP: N-methyl-2-pyrrolidone

[Example 1 (Reference Example)] Preparation Example of Non-Thermoplastic Polyimide Film [Example 1-1] mPI Film 1
The mPI film 1 contains BPDA (75 mol%), ODPA (15 mol%) and PMDA (15 mol%) as acid anhydride monomers, and PDA (70 mol%), BAPP (15 mol%) and BABP as diamine monomers. (15 mol%) is selected, BPDA and PDA are first solution-polymerized, then ODPA, PMDA, BAPP and BABP are added and polymerized, and imidized by a chemical ring-closing method to obtain a non-thermoplastic polyimide (glass). It is a non-stretched film having a transition temperature of 298 ° C. and an imide group density of 0.34).

[Example 1-2] mPI film 2
For mPI film 2, PMDA (9 mol%) and BPDA (91 mol%) were selected as acid anhydride monomers, and m-TB (15 mol%) and TPE-R (85 mol%) were selected as diamine monomers, all of which were selected. This is a non-stretched film of non-thermoplastic polyimide (glass transition temperature: 298 ° C., imide group density: 0.26) obtained by solution-polymerizing the monomers of the above and imidizing them by a chemical ring-closing method.

[Example 1-3] mPI film 3
The mPI film 3 is obtained by selecting BPDA (100 mol%) as an acid anhydride monomer and PDA (100 mol%) as a diamine monomer, solution-polymerizing all the monomers, and imidizing them by a chemical ring closure method. It is a non-stretched film of thermoplastic polyimide (glass transition temperature: 420 ° C., imide group density: 0.38).

[Example 1-4] mPI film 4
For the mPI film 4, BPDA (9 mol%) and PBTA (91 mol%) were selected as the acid anhydride monomers, and m-TB (15 mol%) and PPBA (85 mol%) were selected as the diamine monomers, and all the monomers were selected. Is a non-stretched film of non-thermoplastic polyimide (glass transition temperature: 268 ° C., imide group density: 0.18) obtained by solution polymerization and imidization by a chemical ring closure method.
[Example 1-5] mPI film 5
Non-thermoplastic polyimide (manufactured by SKC Kolon PI, "FS-200"; glass transition temperature: 310 ° C., imide group density: 0.25).
The physical properties of each film are summarized in Table 1.

The physical properties of each polyimide and film were measured by the following methods.
<Glass transition temperature>
A polyimide film was analyzed using a dynamic viscoelasticity measuring device (“DMS6100” manufactured by SII Nanotechnology), and the loss tangent (tan δ), which is the ratio of the loss modulus to the storage modulus, was plotted against temperature. At that time, the temperature at which tan δ became the maximum value was defined as the glass transition temperature of polyimide.
The measurement conditions were a sample measurement range of 9 mm in width, a distance of 20 mm between grippers, a measurement temperature of 0 ° C to 440 ° C, a temperature rise rate of 3 ° C / min, a measurement atmosphere of air, and a strain amplitude of 10 μm. The measurement frequency was 5 Hz, the minimum tension / compressive force was 100 mN, the tension / compression gain was 1.5, and the initial force amplitude was 100 mN.

<Coefficient of linear expansion>
Using a thermomechanical analyzer (“TMA / SS6100” manufactured by SII Nanotechnology Inc.), the polyimide film (width: 3 mm, length: 10 mm) was raised from 0 ° C to 400 ° C at 10 ° C / min. After warming, it was cooled to 10 ° C. at 40 ° C./min and further heated from 10 ° C. to 200 ° C. at 10 ° C./min to determine the coefficient of linear expansion. The measurement load was 29.4 mN, and the measurement atmosphere was an air atmosphere.
<Water absorption rate>
It was measured by the method described later.
<Tension modulus>
The tensile elastic modulus at 320 ° C. was measured using a wide-area viscoelasticity measuring device (RHEOLOGY CO., manufactured by LTD, "DVE RHEO SPECTORER"). The measurement frequency was 10 Hz.

[Example 2 (Reference Example)] Preparation Example of Powder Dispersion Solution of F Polymer [Example 2-1] Dispersion Solution 1
The dispersion liquid 1 contains 98.0 mol%, 0.1 mol%, and 1.9 mol% of TFE units, NAH units, and PPVE units in this order, and is an F polymer 1 having an acid anhydride group (melting temperature: 300). 50 parts by mass of powder (D50: 2.6 μm, D90: 7.1 μm) of ℃), 3 parts by mass of nonionic fluoropolymer, and 47 parts by mass of NMP were put into a pot, and zirconia balls were put into the pot. Is a dispersion liquid in which the powder of F polymer 1 is dispersed in NMP, which is obtained by rolling the pot at 150 rpm for 1 hour.

[Example 2-2] Dispersion liquid 2
The dispersion liquid 2 contains 98.0 mol% and 2.0 mol% of TFE units and PPVE units in this order, and is a powder (D50: 3.) of F polymer 2 having no functional group (melting temperature: 305 ° C.). 50 parts by mass of 5 μm, D90: 9.2 μm), 3 parts by mass of nonionic fluoropolymer, and 47 parts by mass of N-methyl-2-pyrrolidone (NMP) were put into a pot, and zirconia balls were put into the pot. Is a dispersion liquid in which the powder of F polymer 2 is dispersed in NMP, which is obtained by rolling the pot at 150 rpm for 1 hour.

[Example 3 (Reference example)] Example of preparation of copper foil with resin [Example 3-1] Example of preparation of copper foil with resin 1 Disperse liquid 1 is added to electrolytic copper foil 1 (thickness: 18 μm, Rzjis: 1.0 μm, Rq : 0.21 μm; “CF-T4X-SV-18” manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) was coated by a roll-to-roll method by a gravure reverse method to form a liquid film. Next, this liquid film was passed through a drying oven at 120 ° C. for 5 minutes, heated and dried to obtain a dry film. Then, the dry film was heated in a nitrogen oven at 380 ° C. for 3 minutes. As a result, a resin-attached copper foil 1 in which a layer F ¹ (thickness: 25 μm) containing the polymer 1 was formed on the surface of the electrolytic copper foil 1 was obtained. The water absorption of the layer F ¹ measured after an electrolytic copper foil 1 and the etching was 0.01%.
The surface roughness of the copper foil used for adjusting the resin-attached copper foil was measured by the following method.
<Copper foil surface roughness>
The Rzjis value and the Rq value of the surface (matte surface) of the copper foil were measured using a contact type surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., "SURFCOM NEX001"). The measurement terminal uses a terminal with a tip radius of 2 μm and a cone (taper angle: 60 °), and the cutoff values are 0.8 mm for λc and 2.5 μm for λs, and the reference length of the roughness curve is 0.8 mm. The evaluation length of the roughness curve was 4.0 mm.

[Example 3-2] Example of preparation of copper foil 2 with resin Layer F ² (thickness) containing F polymer 2 in the same manner as copper foil 1 with resin except that the dispersion liquid 2 was used instead of the dispersion liquid 1. : A copper foil 2 with a resin on which 25 μm) was formed was obtained. Water absorption of the layer F ² measured after an electrolytic copper foil 1 and the etching was 0.01%.

[Example 3-3] Preparation example of copper foil 3 with resin A varnish containing 10% by mass of aromatic thermoplastic polyimide is applied to the electrolytic copper foil 1 by a roll-to-roll method by a gravure reverse method to form a liquid film. did. Next, this liquid film was passed through a drying oven at 120 ° C. for 5 minutes and at 200 ° C. for 10 minutes, heated and dried to obtain a dry film. As a result, a resin-attached copper foil 3 in which an aromatic thermoplastic polyimide layer PI ¹ (thickness: 25 μm) was formed on the surface of the electrolytic copper foil 1 was obtained. The water absorption rate of the layer PI ¹ measured after etching the electrolytic copper foil 1 was 1.5%.
The water absorption rate of each layer after etching was measured by a method described later.

[Example 3-4] Preparation example of copper foil 4 with resin An electrolytic copper foil 2 (thickness: 18 μm, Rzjis: 1.2 μm, Rq: 0.28 μm; manufactured by Mitsui Metal Mining Co., Ltd., “TQ-M7” A resin-containing copper foil 4 was obtained in the same manner as the resin-containing copper foil 1 except that the value was changed to −VSP-18 ”).
[Example 3-5] Example of preparation of copper foil 5 with resin An electrolytic copper foil 3 (thickness: 18 μm, Rzjis: 0.6 μm, Rq: 0.14 μm; manufactured by Mitsui Metal Mining Co., Ltd., “TQ-M4” A resin-containing copper foil 5 was obtained in the same manner as the resin-containing copper foil 1 except that the value was changed to −VSP-18 ”).

[Example 4] The resin coated copper foil 1 layer F ¹ is arranged to face the respective surfaces of Preparation Example 4-1] Production Example mPI film 1 of the laminated body 1 of the stack, a vacuum hot press ( Press temperature: 320 ° C., press pressure: 2 MPa, press time: 2 minutes), electrolytic copper foil 1 (thickness: 18 μm) and non-thermoplastic polyimide 1 layer P ¹ (mPI film 1; thickness: 50 μm) ) has a further layer ^{F 1} of F polymer 1 on both sides of the layer ^{P 1} (thickness: to obtain a laminate 1 having a 25 [mu] m). The laminate 1 is a laminate having a structure of electrolytic copper foil 1 / layer F ¹ / layer P ¹ / layer F ¹ / electrolytic copper foil 1. Before the vacuum heat press, the surface of the mPI film 1 was subjected to a mixed gas of 95% by volume argon and 5% by volume hydrogen (flow rate:) under the condition of a high frequency voltage of 40 kHz (discharge power density: 300 W / min / m ² ). The surface was treated by vacuum plasma treatment (vacuum degree: 20 Pa) using 2000 sccm).

[Example 4-2] Production example of laminate 2 Electrolytic copper foil 1 / layer F ² / layer in the same manner as in Example 4-1 except that the resin-attached copper foil 2 was used instead of the resin-attached copper foil 1. A laminate 2 having a configuration of P ¹ / layer F ² / electrolytic copper foil 1 was obtained.
[Example 4-3] Production example of laminate 3 Electrolytic copper foil 1 / layer F ¹ / layer P ² (mPI) in the same manner as in Example 4-1 except that the mPI film 2 was used instead of the mPI film ^1. A laminate 3 having a structure of film 2) / layer F ¹ / electrolytic copper foil 1 was obtained.

[Example 4-4] Production example of laminated body 4 Electrolytic copper foil 1 / layer F ¹ / layer P ³ (mPI) in the same manner as in Example 4-1 except that the mPI film 3 was used instead of the mPI film ^1. A laminate 4 having a structure of film 3) / layer F ¹ / electrolytic copper foil 1 was obtained.
[Example 4-5] Production example of laminate 5 Electrolytic copper foil 1 / layer F ¹ / layer P ⁴ (mPI) in the same manner as in Example 4-1 except that the mPI film 4 was used instead of the mPI film ^1. A laminate 5 having a structure of film 4) / layer F ¹ / electrolytic copper foil 1 was obtained.

[Example 4-6] Production example of laminate 6 Electrolytic copper foil 1 / layer PI ¹ / layer in the same manner as in Example 4-1 except that the resin-attached copper foil 3 was used instead of the resin-attached copper foil 1. A laminate 6 having a configuration of P ¹ / layer PI ¹ / electrolytic copper foil 1 was obtained.
[Example 4-7] Production example of laminate 7 Electrolytic copper foil 1 / layer F ¹ / layer P ⁵ (mPI) in the same manner as in Example 4-1 except that the mPI film 5 was used instead of the mPI film ^1. A laminate 7 having a structure of film 5) / layer F ¹ / electrolytic copper foil 1 was obtained.

[Example 4-8] Production Example of Laminated Body 8 A laminated body 8 was obtained in the same manner as in Example 4-1 except that the resin-attached copper foil 4 was used instead of the resin-attached copper foil 1.
[Example 4-9] Production Example of Laminated Body 9 A laminated body 9 was obtained in the same manner as in Example 4-1 except that the copper foil 5 with resin was used instead of the copper foil 1 with resin.

[Example 5] Evaluation example of laminated body Each laminated body was evaluated by the following evaluation items.
<Peel strength>
The laminate was cut into a width of 1 cm, peeled off at an angle of 90 ° and a speed of 50 mm / min, and the peel strength (kN / m) was measured.
<Normal-Electrical characteristics>
The copper foil of each laminate was removed by etching and dried at 100 ° C. for 2 hours to prepare a measurement sample composed of a layer P having layers F on both sides. After holding each measurement sample in an atmosphere of 24 ° C. and 50% relative humidity for 24 hours, the respective dielectric constants (normal-dielectric constant) and dielectric loss tangent (normal-dielectric loss tangent) were measured.
<Humidification-Electrical characteristics>
After measuring the electrical characteristics, each measurement sample was further held at 85 ° C. and an atmosphere of 85% relative humidity for 72 hours. Within 5 minutes after holding, the dielectric constant (humidification-dielectric constant) and dielectric loss tangent (humidification-dielectric loss tangent) of each measurement sample were measured.

<Water absorption rate>
The measurement was performed according to the method of JIS K 7209: 2000A.
First, a copper foil of a laminated body cut into 10 cm squares was removed by etching to prepare a test piece. The test piece was then dried at 50 ° C. for 24 hours and cooled in a desiccator. The mass of the test piece at this point was defined as the mass of the test piece before immersion.
Then, the dried test piece was immersed in pure water at 23 ° C. for 24 hours. Then, the test piece was taken out from pure water, the water on the surface was quickly wiped off, and the mass measured within 1 minute was taken as the mass after immersion of the test piece. The mass change rate of the test piece before and after immersion was determined and used as the "water absorption rate (actual measurement value)" of the laminated body. Further, a value obtained by simply summing the water absorption rates of each layer of the laminated body was defined as "water absorption rate (calculated value)".

<Transmission loss>
A transmission line was formed on each of the laminated bodies to form a printed circuit board. A microstrip line was used to form the transmission line. The 28 GHz signal on the printed circuit board was processed using a vector network analyzer (“E8361A” manufactured by Keysight Technology Co., Ltd.), and the S21 parameter representing the transmission loss was measured using the Universal Test Fixture as a probe. At that time, the characteristic impedance of the line was set to 50Ω, the length of the transmission line of the printed circuit board was set to 50 mm, and the transmission loss was measured.
As a measure of transmission loss, "S21-parameter", which is one of the network parameters used to express the characteristics of high-frequency electronic circuits and high-frequency electronic components, was used as the transmission loss value. This value means that the closer the value is to 0, the smaller the transmission loss.
The transmission loss value of the printed circuit board formed from the laminated body not immersed in pure water is defined as "transmission loss before water absorption", and the printed circuit board formed from the laminated body after being immersed in pure water for 24 hours at 23 ° C. The transmission loss value was defined as "transmission loss after water absorption".

<Solder float resistance>
The appearance of the laminate after being cut into 5 cm squares, immersed in pure water at 24 ° C. for 24 hours, and floated in a solder bath at 260 ° C. for 30 seconds was evaluated according to the following criteria.
○ (Good): No swelling or peeling is seen.
Δ (Yes): No swelling was observed, but some peeling was observed.
× (impossible): Swelling and peeling were observed.

<Waviness after etching treatment>
After removing the copper foil of the laminated body by etching treatment, it was placed on a flat glass and the presence or absence of warpage (waviness) was evaluated according to the following criteria.
○ (Yes): No warpage was seen.
× (impossible): Warpage (waviness) is seen, and there is a part floating from the glass.
The evaluation results are summarized in Tables 2 and 3.

As a result of visually confirming the appearance of each of the laminated bodies, no wrinkles were observed in the appearance of the laminated bodies other than the laminated body 3. The occurrence of wrinkles derived from the layer P was observed in the laminated body 3.
Each laminate was cut into 5 mm squares, bent 180 ° under the condition of radius of curvature (300 μm), applied a load (50 mN, 1 minute) from above, and then unfolded. As a result of checking the appearance, the laminate 1 No abnormal appearance was observed in the creases of the layers 3 and 5 to 9, and whitening was observed in the folds of the laminate 6.

The laminate of the present invention is useful as a material for a printed circuit board. Further, if the printed circuit board of the present invention is used, an antenna having excellent characteristics can be obtained.
The Japanese patent application 2019-077829 filed on April 16, 2019, the Japanese patent application 2019-151453 filed on August 21, 2019, and the Japanese patent filed on October 25, 2019. The entire contents of the specification, the scope of patent claims and the abstract of the application No. 2019-194515 are cited herein and incorporated as disclosure of the specification of the present invention.

Claims (15)

1. A laminated body having at least a three-layer structure having a metal foil layer, a layer P of non-thermoplastic polyimide, and a layer F of a tetrafluoroethylene-based polymer, and at least one of the outermost layers is a metal foil layer. A laminate in which the layer F is present on at least one surface of P, the water absorption rate of the layer P is less than 1.5%, and the absolute value of the linear expansion coefficient is 25 ppm / ° C. or less.
2. The laminate according to claim 1, wherein the layer F is present on both sides of the layer P, which is a laminate having at least a four-layer structure.
3. The laminate according to claim 1 or 2, wherein the root mean square roughness of the surface of the metal foil layer is 0.25 μm or more.
4. The laminate according to any one of claims 1 to 3, wherein the thickness of the metal foil layer is 2 to 30 μm.
5. The laminate according to any one of claims 1 to 4, wherein the non-thermoplastic polyimide is a non-thermoplastic polyimide having a glass transition temperature of 280 ° C. or higher.
6. The laminate according to any one of claims 1 to 5, wherein the non-thermoplastic polyimide is a non-thermoplastic polyimide having a tensile elastic modulus of 0.2 GPa or more at 320 ° C.
7. The laminate according to any one of claims 1 to 6, wherein the non-thermoplastic polyimide has an imide group density of 0.20 to 0.35.
8. The laminate according to any one of claims 1 to 7, wherein the layer P has a thickness of 10 to 100 μm.
9. The laminate according to any one of claims 1 to 8, wherein the tetrafluoroethylene polymer is a heat-meltable tetrafluoroethylene polymer having a melting temperature of 260 to 320 ° C.
10. The laminate according to any one of claims 1 to 9, wherein the layer F has a thickness of 1 to 38 μm.
11. When the laminate is held at 24 ° C. in an atmosphere of 50% relative humidity for 24 hours, the dielectric constant of the layer P in contact with the layer F is 2.8 or less, and the dielectric loss tangent is 0.004 or less. The laminate according to any one of claims 1 to 10, which is a laminate.
12. When the laminate is held in an atmosphere of 85 ° C. and a relative humidity of 85% for 72 hours, the dielectric constant of the layer P in contact with the layer F is 2.8 or less, and the dielectric loss tangent is 0.007 or less. The laminate according to any one of claims 1 to 11, which is a laminate.
13. A method for manufacturing a printed circuit board, wherein the metal foil layer of the laminate according to any one of claims 1 to 12 is etched to form a transmission circuit to obtain a printed circuit board.
14. A printed circuit board having a layer P of non-thermoplastic polyimide, a layer F of a tetrafluoroethylene-based polymer existing on at least one surface of the layer P, and a transmission circuit existing on at least one surface thereof. A printed circuit board in which the water absorption rate of the layer P is less than 1.5% and the absolute value of the linear expansion coefficient is 25 ppm / ° C. or less.
15. An antenna formed from the printed circuit board according to claim 14.