JP7283208B2 - Powder dispersion, method for producing laminate, method for producing laminate and printed circuit board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a powder dispersion, a method for producing a laminate, and a method for producing a laminate and a printed circuit board.

Tetrafluoroethylene polymers such as polytetrafluoroethylene (PTFE) have excellent physical properties such as chemical resistance, water and oil repellency, heat resistance, and electrical properties, and are used in various forms such as powders, dispersions, and films. and various uses are known. In recent years, powder dispersion containing tetrafluoroethylene-based polymer powder has been developed as a material for forming the dielectric layer of printed circuit boards, which has excellent electrical properties such as low dielectric constant and low dielectric loss tangent, and is compatible with high-band frequencies. Attention has been paid.

Patent Document 1 proposes a powder dispersion containing the powder, a thermoplastic elastomer, and an organic solvent from the viewpoint of improving the viscosity, storage stability, and miscibility with other resin materials of the powder dispersion. .
In Patent Document 2, from the viewpoint of improving the adhesion to the substrate and the thickness uniformity of the dielectric layer when the dielectric layer is formed, the powder, the particulate elastomer, the silica filler, the epoxy resin, and the curing Thermosetting powder dispersions containing agents have been proposed.

JP 2017-222762 A JP 2019-035059 A

A powder dispersion containing a layer-forming component other than a tetrafluoroethylene-based polymer can be expected to improve handling properties and partial physical properties of the layer. There is
Specifically, although the dielectric layer formed from the powder dispersion of Patent Document 1 has improved flexibility, it has a high coefficient of linear expansion and low dimensional stability. Therefore, the printed circuit board material having the dielectric layer tends to warp in a high-temperature environment such as a solder reflow process and is difficult to use.

In addition, since the dielectric layer formed from the powder dispersion of Patent Document 2 contains a large amount of cured epoxy resin, the low water absorbency of the tetrafluoroethylene-based polymer is impaired. Therefore, the printed circuit board material having the dielectric layer is difficult to use due to its water absorbency. In addition, the printed circuit board material has low flexibility and is difficult to use flexibly.
The present invention provides a powder dispersion capable of forming a low water-absorbing layer that is excellent in dimensional stability and flexibility and can also be used for applications such as flexible printed circuit boards, a laminate having such a layer, a method for producing the same, and printing An object of the present invention is to provide a method for manufacturing a substrate.

The present invention has the following aspects.
<1> Contains a layer-forming component containing a powder of a tetrafluoroethylene-based polymer, an inorganic filler, and an elastomer, and a solvent, and the total proportion of the tetrafluoroethylene-based polymer and the inorganic filler in the layer-forming component is 65. % by mass or more, and a ratio by mass of the amount of the inorganic filler to the amount of the tetrafluoroethylene-based polymer contained in the layer-forming component is more than 1.25.
<2> The powder dispersion according to <1> above, wherein the ratio by mass of the amount of the elastomer to the amount of the tetrafluoroethylene-based polymer contained in the layer-forming component is 0.05 or more.
<3> The powder dispersion of <1> or <2> above, further comprising a polymer having a polyfluoroalkyl group or polyfluoroalkenyl group and a hydroxyl group or a polyoxyalkylene group.
<4> Furthermore, <1> to the above, including a polymer having a polyfluoroalkyl group or a polyfluoroalkenyl group and a hydroxyl group, a fluorine content of 10 to 50% by mass, and a hydroxyl value of 10 to 100 mg/KOH The powder dispersion according to any one of <3>.
<5> The powder dispersion according to any one of <1> to <4> above, wherein the solvent is a ketone, amide or ester.
<6> Any one of <1> to <5> above, wherein the elastomer comprises at least one thermoplastic elastomer selected from the group consisting of butylene/isoprene/butadiene elastomers, styrene elastomers, and fluorine elastomers. Powder dispersion.
<7> The powder dispersion according to any one of <1> to <6>, wherein the tetrafluoroethylene polymer has a melting temperature of 140 to 320°C.
<8> The powder dispersion according to any one of the above <1> to <7>, which has a viscosity of 10 to 10000 mPa·s at 25°C.
<9> The powder dispersion according to any one of <1> to <8>, which is used for forming a flexible printed circuit board.
<10> The powder dispersion of any one of <1> to <9> above is applied to the surface of a metal foil and heated to obtain the metal foil and the tetrafluoro formed on the surface of the metal foil. A method for producing a laminate, comprising obtaining a laminate having a layer containing an ethylene-based polymer, the inorganic filler, and the elastomer.
<11> The manufacturing method according to <10> above, wherein the layer has a thickness of 50 to 150 μm.
<12> A metal foil and a layer containing a tetrafluoroethylene-based polymer, an inorganic filler, and an elastomer formed on the surface of the metal foil, wherein the tetrafluoroethylene-based polymer and the inorganic filler occupy the layer. is 65% by mass or more, and the ratio by mass of the amount of the inorganic filler to the amount of the tetrafluoroethylene-based polymer contained in the layer is more than 1.25.
<13> The laminate according to <12>, which is used to form a flexible printed circuit board.
<14> A method for manufacturing a printed circuit board, wherein the metal foil of the laminate of <12> or <13> is processed to form a pattern circuit.
<15> The manufacturing method according to <14> above, wherein the printed circuit board is a flexible printed circuit board.

INDUSTRIAL APPLICABILITY According to the present invention, a powder dispersion capable of forming a layer having excellent dimensional stability and flexibility and low water absorption, a laminate having such a layer, a method for producing the same, and a method for producing a printed circuit board are provided. The powder dispersion or laminate of the present invention is useful as a material for forming a flexible printed circuit board.

The following terms have the following meanings.
"Powder D50" is the volume-based cumulative 50% diameter of the powder determined by the laser diffraction/scattering method. That is, the particle size distribution is measured by a laser diffraction/scattering method, and the cumulative curve is obtained with the total volume of the group of particles being 100%.
"Powder D90" is the volume-based cumulative 90% diameter of the powder determined by the laser diffraction/scattering method. That is, the particle size distribution is measured by a laser diffraction/scattering method, a cumulative curve is obtained with the total volume of the group of particles being 100%, and the particle diameter at the point where the cumulative volume is 90% on the cumulative curve.
The D50 and D90 of the powder are obtained by dispersing the powder in water and analyzing it by a laser diffraction/scattering method using a laser diffraction/scattering particle size distribution analyzer (manufactured by Horiba, Ltd., LA-920 measuring instrument). .
The "melting temperature of a polymer" is the temperature corresponding to the maximum melting peak measured by differential scanning calorimetry (DSC).
"Polymer melt viscosity" is measured in accordance with ASTM D 1238 using a flow tester and a 2Φ-8L die, and a polymer sample (2g) preheated at the measurement temperature for 5 minutes under a load of 0.7MPa. It is a value measured by holding at the measurement temperature.
"Powder dispersion viscosity" is the viscosity of a liquid measured using a Brookfield viscometer at room temperature (25°C) and a rotation speed of 30 rpm. The measurement is repeated 3 times, and the average value of the 3 measurements is taken.
The "thixotropic ratio of the powder dispersion" is a value calculated by dividing the viscosity _η1 measured at a rotation speed of 30 rpm by the viscosity _η2 measured at a rotation speed of 60 rpm. Each viscosity measurement is repeated three times, and the average value of the three measurements is taken.
"Ten-point average roughness (Rzjis)" is a value specified in Annex JA of JIS B 0601:2013.
The "peel strength" is a rectangular shape (length 100 mm, width 10 mm), fixed at a position 50 mm from one end in the length direction of the laminate, pulled at a rate of 50 mm / min, and the laminate from one end in the length direction. It is the maximum load (N/cm) applied when the F layer and the metal foil are separated at 90° to .
A "unit" in a polymer means an atomic group based on the monomer formed by polymerization of the monomer. The units may be units directly formed by a polymerization reaction, or may be units in which some of said units have been converted to another structure by treatment of the polymer. Hereinafter, units based on monomer a are also simply referred to as "monomer a units".

The powder dispersion of the present invention comprises a powder of a tetrafluoroethylene polymer (hereinafter also referred to as "F polymer") (hereinafter also referred to as "F powder"), a layer-forming component containing an inorganic filler and an elastomer, and a solvent. including. The powder dispersion of the present invention can also be said to be a dispersion in which at least part of the layer-forming components (such as F powder) is dispersed in a solvent in the form of particles.
The total proportion of the F polymer and the inorganic filler in the layer-forming components in the present invention is 65% by mass or more. Also, the ratio by mass of the amount of inorganic filler to the amount of F polymer contained in the layer-forming components in the present invention is greater than 1.25. F polymers are polymers that do not have rubber elasticity and are different from elastomers.

The layer formed from the powder dispersion of the present invention (hereinafter also referred to as "F layer") maintains the original physical properties (electrical properties, etc.) of the F polymer, and is excellent in dimensional stability and flexibility. and low water absorption. The reason for this is not necessarily clear, but is considered as follows.
The inorganic filler is a component capable of reducing the high coefficient of linear expansion, which is a weak point of the F layer due to the F polymer, without impairing the physical properties of the F polymer. Since the F layer contains a large amount of inorganic filler, the effect of lowering the coefficient of linear expansion of the F layer is remarkable, and as a result, it is considered that the dimensional stability of the F layer is improved.

In addition, it is considered that the low water absorbency of the F polymer was not impaired and the F layer exhibited low water absorbency because the total proportion of the F polymer and the inorganic filler in the F layer-forming components was high.
Furthermore, it is considered that the layer-forming elastomer functioned as a rubber component to develop the excellent flexibility (bendability) of the F layer. Such an elastomer also acts to facilitate the dispersion of the powder dispersion liquid of the F polymer and the inorganic filler, and is also considered to contribute to uniform distribution density of each component in the F layer.

In particular, in the present invention, since the amount of each component of the layer-forming components is defined within a predetermined range, each component is unlikely to interfere with each other's functions, and the physical properties based on each component are well-balanced and uniformly exhibited in the F layer. presumed to have been
Therefore, since the F layer has dimensional stability and flexibility and is excellent in low water absorption, a laminate having the F layer, for example, a metal foil having the F layer on the surface, has particularly high bendability and is flexible. It can be suitably used for manufacturing printed circuit boards.
The effects as described above are remarkably exhibited in preferred embodiments of the present invention, which will be described later.

D50 of the F powder in the present invention is preferably 40 µm or less, more preferably 20 µm or less, and even more preferably 8 µm or less. D50 of the F powder is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more. Moreover, D90 of the F powder is preferably 80 μm or less, more preferably 10 μm or less. In this range of D50 and D90, the fluidity and dispersibility of the F powder are good, and the electric properties (low dielectric constant, etc.) and heat resistance of the F layer are most easily exhibited.
The loosely packed bulk density of the F powder is preferably 0.08 to 0.5 g/mL. The close-packed bulk density of F powder is preferably 0.1 to 0.8 g/mL. When the sparsely packed bulk density or densely packed bulk density is within the above range, the F powder has excellent handleability.

The F powder in the present invention may contain a resin other than the F polymer, but preferably contains the F polymer as a main component. The content of the F polymer in the F powder is preferably 80% by mass or more, more preferably 100% by mass.
Examples of the resin include aromatic polyester, polyamideimide, thermoplastic polyimide, polyphenylene ether, and polyphenylene oxide.

An F polymer in the present invention is a polymer containing units based on tetrafluoroethylene (TFE) (TFE units). The F polymer may be a homopolymer of TFE or a copolymer of TFE and other monomers (comonomers) copolymerizable with TFE.
The F polymer preferably contains 90 to 100 mol % of TFE units with respect to all units constituting the polymer. Moreover, the fluorine content of the F polymer is preferably 70 to 76% by mass, more preferably 72 to 76% by mass.

F polymers include polytetrafluoroethylene (PTFE), copolymer of TFE and ethylene (ETFE), copolymer of TFE and propylene, copolymer of TFE and perfluoro(alkyl vinyl ether) (PAVE) (PFA), TFE and hexa Copolymers of fluoropropylene (HFP) (FEP), copolymers of TFE and fluoroalkylethylenes (FAE), and copolymers of TFE and chlorotrifluoroethylene (CTFE). The copolymers may also contain units based on other comonomers.
Examples of PTFE include high-molecular-weight PTFE, low-molecular-weight PTFE, and modified PTFE having fibril properties. Low molecular weight PTFE or modified PTFE also includes copolymers of TFE and trace amounts of comonomers (HFP, PAVE, FAE, etc.).

The F polymer is preferably an F polymer with TFE units and functional groups. The functional group is preferably a carbonyl group-containing group, hydroxy group, epoxy group, amide group, amino group or isocyanate group.
The functional groups may be contained in units in the F polymer or may be contained in terminal groups of the main chain of the polymer. Further, an F polymer having a functional group obtained by plasma treatment or ionizing radiation treatment of the F polymer can also be used.
The F polymer having a functional group is preferably an F polymer having a TFE unit and a unit having a functional group from the viewpoint of the dispersibility of the F powder in the powder dispersion. The unit having a functional group is preferably a unit based on a monomer having a functional group, and more preferably a unit based on the above-described monomer having a functional group.
The monomer having a functional group is preferably a monomer having an acid anhydride residue, such as itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic anhydride (also known as Himic anhydride, hereinafter referred to as "NAH"). Also described.) or maleic anhydride is more preferable.

Suitable specific examples of F polymers having functional groups include F polymers having TFE units, HFP units, PAVE units or FAE units, and units having functional groups.
_As PAVE _{, CF2} = _CFOCF3 (PMVE ₎ , _CF2 = _CFOCF2CF3 , _CF2 = _CFOCF2CF2CF3 (PPVE), _CF2 = _{CFOCF2CF2CF2CF3 , CF2 = CFO} (CF ₂ ) ₈ F can be mentioned.
As FAE, _CH2 =CH( _CF2 ) _2F , _CH2 =CH( _CF2 ) _3F , _CH2 =CH( _CF2 ) _4F , _CH2 =CF( _CF2 ) _3H , _CH2 =CF( _CF2 ) _4H .
Specific examples of such F polymers include 90 to 99 mol% of TFE units, 0.5 to 9.97 mol% of HFP units, PAVE units or FAE units, and functional groups, based on the total units constituting the polymer. Examples are F polymers containing 0.01 to 3 mol % of each unit. Specific examples of such F polymers include the polymers described in WO2018/16644.

The melt viscosity of the F polymer at 380° C. is preferably 1×10 ² to 1×10 ⁶ Pa·s, more preferably 1×10 ³ to 1×10 ⁶ Pa·s.
The melting temperature of the F polymer is preferably 140 to 320°C, more preferably 200 to 320°C, even more preferably 260 to 320°C. The use of such an F polymer facilitates the formation of an F layer with superior surface flatness.

The inorganic filler in the present invention is preferably a filler that lowers the coefficient of linear expansion of the F layer, and more preferably a filler that has a low dielectric constant and a low dielectric loss tangent. If the powder dispersion liquid of the present invention contains an inorganic filler having a low dielectric constant and a low dielectric loss tangent, the electrical properties of the laminate and the printed circuit board to be described later are likely to be improved.
Examples of inorganic fillers or compounds forming them include silica, clay, talc, calcium carbonate, mica, diatomaceous earth, alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, cerium oxide, tin oxide, and antimony oxide. , calcium hydroxide, magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate, non-basic magnesium carbonate, zinc carbonate, barium carbonate, dawsonite, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate, boron nitride, Aluminum nitride, zinc borate, montmorillonite, forsterite, steatite, cordierite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass chopped fiber, glass beads, silica balloon, carbon black, carbon nanotube, Carbon nanohorns, graphite, carbon fibers, glass balloons, carbon balloons, and wood powders. These inorganic fillers may be used alone or in combination of two or more.

Among them, inorganic fillers made of silica, alumina, magnesium oxide, forsterite, boron nitride, or aluminum nitride are preferable as the inorganic filler because of their low dielectric loss tangent.
Specific examples of inorganic fillers include fibrous magnesium sulfate (manufactured by Ube Materials Co., Ltd., trade name "Mos-Hige", etc.), glass cut fiber (manufactured by Nittobo Co., Ltd., trade names "PF", "SS", etc.). is mentioned.
In addition, the F layer formed from the powder dispersion containing the inorganic filler tends to increase the absorption of light with wavelengths in the ultraviolet region, particularly light with wavelengths of 266 nm and 355 nm, and UV-YAG using light with such wavelengths. Improves laser workability. Therefore, a more highly accurate printed circuit board can be easily manufactured from the later-described laminate.
From the viewpoint of maintaining or improving the bendability of the F layer, the shape of the inorganic filler is preferably granular (spherical, amorphous), and more preferably granular with a particle size of 1 μm or less. Also, an inorganic filler having an aspect ratio of 2 or more and an inorganic filler having an aspect ratio of 1 to 2 may be used together.
The inorganic filler may be surface-treated with a silane coupling agent or the like.
The water absorption rate of the inorganic filler is preferably 3% or less, more preferably 1% or less.

The elastomer in the present invention is preferably at least one thermoplastic elastomer selected from the group consisting of butylene/isoprene/butadiene elastomers, styrene elastomers and fluoroelastomers. These thermoplastic elastomers not only have a low dielectric loss tangent and excellent heat resistance, but also easily disperse or dissolve uniformly in the powder dispersion.
A butylene/isoprene/butadiene elastomer is an elastomer containing at least one monomer selected from the group consisting of butylene, isoprene and butadiene in an arbitrary ratio. ).
As the styrene-based elastomer, block copolymers having polystyrene blocks as hard segments and polyolefin blocks as soft segments are preferred. Each block preferably forms a diblock or triblock.
Specific examples of styrene elastomers include SBS (polystyrene-polybutadiene block-polystyrene), SEP (polystyrene-poly(ethylene/propylene) block), SEPS (polystyrene-poly(ethylene/propylene) block-polystyrene), SEBS (polystyrene - poly(ethylene/butylene) block - polystyrene)
Examples include SEEPS (polyethylene/poly(ethylene-ethylene/propylene) block-polystyrene) and SIS (polystyrene-polyisoprene block-polystyrene).
Examples of fluorine-based elastomers include FKM (vinylidene fluoride-based polymer), FEPM (TFE/propylene-based polymer), and FFKM (TFE/PMVE-based polymer). The TFE/propylene-based polymer means a polymer containing TFE units and propylene units, and the notation for other fluorine-based polymers has the same meaning.

These elastomers are preferably modified to have functional groups in order to improve adhesion with the F polymer and inorganic filler. Such functional groups include epoxy groups, carbonyl group-containing groups, hydroxyl groups, isocyanate groups, and amino groups.
The glass transition temperature of the elastomer is preferably 10°C or lower, more preferably 5°C or lower. If the elastomer has a glass transition temperature of 10° C. or less, the rubber elasticity is improved, and the bendability of the F layer is further improved.
Also, the elastomer is preferably solvent-soluble, but may be solvent-insoluble. The latter elastomer is preferably an elastomer that is dispersed in a powder dispersion.

Such solvent-insoluble elastomer particles include core-shell elastomer particles and crosslinked elastomer particles (crosslinked SBS particles, etc.). Among them, as the solvent-insoluble elastomer particles, core-shell type elastomer particles are preferable from the viewpoint of further improving the bendability of the F layer.
Core-shell type elastomer particles are elastomer particles comprising a core layer and a shell layer covering the surface of the core layer.
Core-shell type elastomeric particles include elastomeric particles comprising a core layer made of a polymer having a relatively low glass transition temperature and a shell layer made of a polymer having a relatively high glass transition temperature. Among them, elastomer particles containing a core layer made of a rubber-like polymer (elastomer) and a shell layer made of a glass-like polymer (non-elastomer) are preferable as the core-shell type elastomer particles. The shell layer of such core-shell type elastomer particles can exhibit the effect of suppressing aggregation between particles and the effect of improving dispersibility in powder dispersion liquid, and the core layer can exhibit the effect of exhibiting excellent rubber elasticity (F layer The effect of imparting excellent flexibility to ) can be exhibited.

The core-shell type elastomer particles may have a two-layer structure containing only a core layer and a shell layer, or may have a laminated structure of three or more layers containing arbitrary layers.
For example, the core-shell type elastomer particles may contain any layer between the core layer and the shell layer, or may contain any layer inside the core layer.
Specific examples of core-shell type elastomer particles having such a laminated structure include a core layer made of a rubber-like polymer, a shell layer made of a glassy polymer, and an arbitrary layer made of a glassy polymer inside the core layer. and an elastomeric particle comprising a layer of

In the core-shell type elastomer particles, glassy polymers include acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene and styrene-divinylbenzene copolymers. Among them, as the glassy polymer, an acrylic polymer is preferable, and polymethyl methacrylate is more preferable.
On the other hand, the above fluorine-based elastomers and styrene-based elastomers can be suitably used as rubber-like polymers.
The above elastomer particles may be used singly or in combination of two or more.
The F layer containing elastomer particles not only has excellent bending properties, but also has high mechanical strength due to the rubber elasticity improving action and stress relaxation action of the elastomer particles.

The average particle size of the elastomer particles in the powder dispersion is preferably 10 µm or less, more preferably 3 µm or less, even more preferably 1 µm or less, particularly preferably 0.5 µm or less, and most preferably 0.3 µm or less. Elastomer particles having such an average particle size can be stably dispersed in a powder dispersion.
The method for measuring the average particle size of the elastomer particles is the same as the method for measuring the F powder.

The solvent in the present invention is preferably a polar solvent that is liquid at 25°C. The solvent may be an aqueous solvent or a non-aqueous solvent. Moreover, a solvent may be used individually by 1 type, or may use 2 or more types together.
Such solvents are preferably ketones, amides, esters, alcohols, sulfoxides or glycol ethers, more preferably ketones, amides or esters, even more preferably ketones or amides.
Specific examples of solvents include methanol, ethanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, diethyl ether, dioxane, ethyl lactate, ethyl acetate, acetic acid. Butyl, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, ethylene glycol monoisopropyl ether, γ-butyrolactone, cellosolve (methyl cellosolve, ethyl cellosolve, etc.), ethyl acetate, acetic acid Isopropyl, butyl acetate, isobutyl acetate can be mentioned.
Among them, the solvent is preferably methyl ethyl ketone, cyclohexanone or N-methyl-2-pyrrolidone.

The powder dispersion liquid preferably further contains a dispersant from the viewpoint of further improving the dispersibility of the F powder. The dispersant is a compound having a hydrophilic group and a hydrophobic group, preferably a fluorine-based dispersant, a silicone-based dispersant or an acetylene-based dispersant, more preferably a fluorine-based dispersant. Also, the dispersant is preferably nonionic.
As the hydrophilic group, a hydroxyl group or a polyoxyalkylene group is preferable. On the other hand, the hydrophobic group is appropriately selected according to the type of dispersant, and in the case of a fluorine-based dispersant, a polyfluoroalkyl group or polyfluoroalkenyl group is preferred.
In this case, the affinity of the dispersant for each component is balanced, and in addition to the dispersibility of the F powder in the powder dispersion liquid, the film formability of the F powder tends to be further improved.

The fluorine-based dispersant is preferably a polymer having a polyfluoroalkyl group or polyfluoroalkenyl group and a hydroxyl group or polyoxyalkylene group.
The fluorine content of the polymer is preferably 10 to 50% by mass.
The hydroxyl value of the polymer is preferably 10-100 mg/KOH, more preferably 10-35 mg/KOH.
The oxyalkylene group content of the polymer is preferably 10 to 70% by mass.
More preferably, the polymer has a polyfluoroalkyl group or a polyfluoroalkenyl group and a hydroxyl group, has a fluorine content of 10 to 50% by mass, and has a hydroxyl value of 10 to 100 mg/KOH.
In this case, the affinity of the polymer for each component is balanced, and in addition to the dispersibility of the powder dispersion, the formability of the F layer tends to be improved. In addition, the wettability of the F layer is improved, and the adhesiveness of the F layer is excellent.
At least a portion of the polyfluoroalkyl group should form a polyfluoroalkyl group, and an etheric oxygen atom may exist between the carbon atom-carbon atom bonds of the residue. That is, the polyfluoroalkyl group may be a polyfluoroalkyl group having an etheric oxygen atom.
Moreover, the polymer may have a hydroxyl group or a carboxyl group at the end of the main chain. In this case, the leveling property of the powder dispersion of the present invention is likely to be improved. Such polymers can be obtained by adjusting the types of polymerization initiators and chain transfer agents used in their production.

Examples of the polymer include polymers containing units based on fluoro(meth)acrylate and units based on oxyalkylene glycol mono(meth)acrylate. This polymer is a polymer other than the F polymer.
Specific examples of the former (meth)acrylate include _CH2 =C( _CH3 )C(O) _OCH2CH2 ( _CF2 ) _6F , _CH2 = _CHC (O) _OCH2CH2 ( _{CF2 ) 6F} , _CH2 =C( _CH3 )C(O) _OCH2CH2 ( _{CF2 ) 4F} , _CH2 =CClC(O) _OCH2CH2 ( _CF2 ) _4F , _CH2 =C ₍ CH ₃ ) C(O _{) OCH2CH2CH2CH2OCF ( CF3} )C(=C( _CF3 ) ₂ )(CF( _{CF3 ) 2} ), _CH2 = _CH3C (O) _{OCH2CH 2CH2CH2OCF} ( _CF3 )C(=C( _CF3 ) _{2 )} (CF( _CF3 ) _{2 )} .

Specific examples of the latter (meth)acrylate include _CH2 = _{C ( CH3} )C(O)( _OCH2CH2 ) _4OH , _CH2 =C( _CH3 )C(O)( _OCH2CH2 ) ₉ OH, _CH2 =C( _CH3 )C(O)( _OCH2CH2 ) _{23 OH} , _CH2 =C( _CH3 )C(O)( _{OCH2CH2 ) 66} OH, _CH2 =C ( _gCH3 )C(O)( _OCH2CH2 ) _{90OH , CH2} =C _{( CH3} )C(O)( _{OCH2CH2 ) 120OH} , _CH2 =CHC(O)( _OCH2CH2 ) _4OH , _CH2 =CHC(O)( _OCH2CH2 ) _8OH , _CH2 =C( _CH3 )C(O)( _OCH2CH ( _CH3 ) _{) 4OH} , _CH2 =C(CH ₃ ) C(O)( _OCH2CH ( _CH3 )) _8OH , _CH2 =C( _CH3 )C(O)( _OCH2CH ( _CH3 )) _9OH , _CH2 =C( _CH3 ) C(O)( _OCH2CH ( _CH3 )) _13OH , _CH2 =C( _CH3 )C(O)( _OCH2CH2 ) _4. ( _{OCH2CH ( CH3} )) _3OH , _{CH2 =} C( _{CH3 ) C} (O)( _OCH2CH2 ) _10- ( _{OCH2CH2CH2CH2 ) 5OH} .
The weight average molecular weight of the polymer is preferably 2,000 to 80,000, more preferably 6,000 to 20,000.

The layer-forming component in the present invention comprises an organic component (polymer such as F polymer, elastomer, etc.) and an inorganic component (inorganic filler, etc.), which form the F layer contained in the powder dispersion.
The total proportion of the F polymer and the inorganic filler in the layer-forming components is 65% by mass or more, preferably 75% by mass or more, more preferably 85 to 99% by mass. In addition, the mass ratio of the amount of the inorganic filler to the amount of the F polymer contained in the layer-forming component (content of the inorganic filler/content of the F polymer) is more than 1.25, more preferably 1.30 or more. 1.5 or more is more preferable. The upper limit of the mass ratio is preferably 5 or less, more preferably 4 or less. If the amounts of the F polymer and the inorganic filler satisfy the above relationship, the F layer will have sufficiently low linear expansion coefficient and water absorbency while maintaining high electrical properties.
Specifically, the proportion of the F polymer in the powder dispersion is preferably 10 to 40% by mass, more preferably 15 to 30% by mass. Also, the proportion of the inorganic filler in the powder dispersion is preferably 12.5 to 50% by mass, more preferably 25 to 37.5% by mass.

The ratio by mass of the amount of elastomer to the amount of F polymer contained in the layer-forming component (elastomer content/F polymer content) is preferably 0.05 or more, more preferably 0.1 or more, and 0.05 or more. 1 to 1 are more preferred. In this case, the foldability of the F layer can be sufficiently enhanced.
Specifically, the proportion of the elastomer in the powder dispersion is preferably 0.25 to 5% by mass, more preferably 0.5 to 3.5% by mass.
The proportion of the solvent in the powder dispersion is preferably 15-55% by mass, more preferably 25-50% by mass. In this case, the coating property of the powder dispersion liquid is excellent, and the formation property of the F layer is likely to be improved.
Further, when the powder dispersion contains a dispersant, its proportion in the powder dispersion is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. In this case, the dispersibility of the F powder in the powder dispersion is further enhanced, and the physical properties of the F layer are more likely to be improved.

The powder dispersion liquid of the present invention may contain other resin materials as long as the effects of the present invention are not impaired.
Such other resin materials include epoxy resins, polyimide resins, polyamic acids that are polyimide precursors, acrylic resins, phenolic resins, liquid crystalline polyester resins, polyolefin resins, modified polyphenylene ether resins, polyfunctional cyanate ester resins, polyfunctional Maleimide-cyanate ester resin, polyfunctional maleimide resin, vinyl ester resin, urea resin, diallyl phthalate resin, melanin resin, guanamine resin, melamine-urea cocondensation resin, styrene resin, polycarbonate resin, polyarylate resin, polysulfone, poly Allyl sulfone, aromatic polyamide resin, aromatic polyether amide, polyphenylene sulfide, polyallyl ether ketone, polyamide imide, and polyphenylene ether. These other resin materials may or may not dissolve in the powder dispersion. Also, the other resin material may be thermosetting or thermoplastic. Also, the other resin material may be modified.
The powder dispersion of the present invention contains a thixotropic agent, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, and a lubricant as long as the effects of the present invention are not impaired. , an antistatic agent, a whitening agent, a coloring agent, a conductive agent, a release agent, a surface treatment agent, a viscosity modifier, and a flame retardant.

The viscosity of the powder dispersion of the present invention is preferably 10 to 10,000 mPa·s, more preferably 100 to 5,000 mPa·s, even more preferably 500 to 3,000 mPa·s. In this case, not only is the powder dispersion excellent in dispersibility, but even if there are fine irregularities on the surface of the substrate when forming a layer on the substrate, the powder dispersion is sufficiently filled with the irregularities. Therefore, it is easy to form an F layer with high surface flatness, and when a thick coating film is formed, the coating film tends to be uniform during drying.
Further, the thixotropic ratio (η ₁ /η ₂ ) of the powder dispersion of the present invention is preferably 1-2.2, more preferably 1.5-2. In this case, not only is the powder dispersion excellent in dispersibility, but the homogeneity of the F layer tends to be improved.

As described above, the powder dispersion of the present invention is excellent in dimensional stability and flexibility, and can form an F layer with low water absorption. In addition, the F layer has excellent electrical properties (low dielectric constant, low dielectric loss tangent, etc.) because the properties of the F polymer are less likely to be impaired. Such an F layer is suitable for use as an insulating layer (dielectric layer) of a flexible printed circuit board. That is, the powder dispersion of the present invention can be suitably used for producing a laminate having a metal foil and an F layer formed on the surface of the metal foil, which is suitably used for forming a flexible printed circuit board. .
In the method for producing a laminate of the present invention, the powder dispersion is applied to the surface of a metal foil and heated to remove the metal foil, the F polymer, the inorganic filler and the elastomer formed on the surface of the metal foil. to obtain a laminate having an F layer containing

Materials for the metal foil in the present invention include copper, copper alloys, stainless steel, nickel, nickel alloys (including 42 alloys), aluminum, aluminum alloys, titanium, titanium alloys, and the like.
Examples of metal foil include rolled copper foil and electrolytic copper foil. The surface of the metal foil may be subjected to antirust treatment (such as an oxide film such as chromate) or may be roughened.
The ten-point average roughness of the surface of the metal foil is preferably 0.2 to 1.5 μm. In this case, the adhesiveness with the F layer tends to be good.
The thickness of the metal foil may be any thickness that can exhibit its function in the application of the laminate (in particular, flexible printed circuit board).
The surface of the metal foil may be treated with a silane coupling agent, the entire surface of the metal foil may be treated with the silane coupling agent, or a portion of the surface of the metal foil may be treated with the silane coupling agent. may have been

As the metal foil, a metal foil with a carrier containing two or more layers of metal foil may be used. As the metal foil with a carrier, a copper foil with a carrier comprising a copper foil with a thickness of 10 to 35 μm and an ultra-thin copper foil with a thickness of 2 to 5 μm laminated on the copper foil with a release layer interposed therebetween. is mentioned.
By peeling off only the carrier copper foil of such a carrier-attached copper foil, a metal-clad laminate having an ultra-thin copper foil can be easily formed. By using this metal-clad laminate, it is possible to form a fine pattern using an ultra-thin copper foil layer as a plating seed layer by the 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 multi-layer metal layer obtained by stacking these metal layers. With such a release layer, the carrier metal foil can be easily separated from the ultra-thin metal foil even through a process at 300° C. or higher.
A specific example of the carrier-attached metal foil is the trade name "FUTF-5DAF-2" manufactured by Fukuda Metal Foil & Powder Co., Ltd.

The method of applying the powder dispersion may be any method as long as it forms a stable liquid film (wet film) on the surface of the metal foil, such as a spray method, a roll coating method, a spin coating method, a gravure coating method, or a micro gravure coating method. , gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, fountain-meyer bar method, slot die coating method and comma coating method. Among them, the die coating method or the comma coating method is preferable as the coating method.
When heating, the liquid film of the powder dispersion is held at the volatilization temperature of the solvent, the liquid film is dried to obtain a dry film (dry film), and then the dry film is held at a temperature higher than the volatilization temperature of the solvent. It is preferable to sinter the F powder.
The "volatilization temperature of the solvent" is preferably ±50° C. of the boiling point of the solvent, more preferably a temperature equal to or higher than the boiling point of the solvent, and even more preferably a temperature of +50° C. or less of the boiling point of the solvent. Drying temperature means the temperature of the drying atmosphere.

Drying may be performed in one step at a constant temperature, or in two or more steps at different temperatures. Drying methods include a method using an oven, a method using a ventilation drying oven, and a method of irradiating heat rays such as infrared rays. Drying may be performed under normal pressure or under reduced pressure. The drying atmosphere may be any of an oxidizing gas atmosphere (oxygen gas, etc.), a reducing gas atmosphere (hydrogen gas, etc.), and an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.). .
The drying temperature is preferably 50 to 280°C, more preferably 120 to 260°C. The drying time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.
By drying the powder dispersion under the conditions as described above, it is possible to suitably manufacture a laminate while maintaining high productivity.

Examples of the baking method include a method using an oven, a method using a ventilation drying oven, and a method of irradiating heat rays such as infrared rays, and these methods may be combined. In order to increase the surface smoothness of the F layer to be obtained, the dried film may be pressed with a heating plate, a heating roll, or the like.
The firing temperature is preferably 300 to 400°C, more preferably 320 to 380°C, even more preferably 340 to 370°C. The firing temperature means the temperature of the firing atmosphere. The baking time is preferably 5 to 60 minutes, more preferably 10 to 45 minutes.
If the firing temperature is set relatively high and the firing time is set relatively long, the dispersant can be sufficiently decomposed and the F powder can be packed more densely. Therefore, the leveling of the F layer is promoted, and the surface smoothness of the F layer is further enhanced. In addition, generation of hydrofluoric acid due to decomposition of the F polymer can be easily suppressed.
Firing may be performed under normal pressure or under reduced pressure. Moreover, the firing atmosphere may be any of an oxidizing gas atmosphere, a reducing gas atmosphere and an inert gas atmosphere. However, if the firing atmosphere contains oxygen gas, the decomposition of the dispersant can be further accelerated.

The laminate of the present invention has a metal foil and an F layer containing an F polymer, an inorganic filler and an elastomer formed on the surface of the metal foil.
The total proportion of the F polymer and the inorganic filler in the F layer of the laminate is 65% by mass or more, preferably 75% by mass or more, and more preferably 90 to 99% by mass.
In addition, the ratio by mass of the amount of inorganic filler to the amount of F polymer in the F layer of the laminate (content of inorganic filler/content of F polymer) is more than 1.25, and 1.5 or more More preferably, 2 or more. The upper limit of the mass ratio is preferably 5 or less, more preferably 4 or less. If the amounts of the F polymer and the inorganic filler satisfy the above relationship, the F layer will have sufficiently low linear expansion coefficient and water absorbency while maintaining high electrical properties.
Specifically, the proportion of the F polymer in the F layer is preferably 10 to 50% by mass, more preferably 15 to 40% by mass. Also, the proportion of the inorganic filler in the F layer is preferably 30 to 85% by mass, more preferably 40 to 80% by mass.

The mass ratio of the amount of elastomer to the amount of F polymer contained in the F layer of the laminate (content of elastomer/content of F polymer) is preferably 0.05 or more, more preferably 0.1 or more. The upper limit of the mass ratio is preferably 0.5 or less, more preferably 0.3 or less. In this case, the bendability of the F layer can be sufficiently improved without impairing the electrical properties of the F layer of the laminate.
Specifically, the proportion of the elastomer in the F layer is preferably 0.5 to 10% by mass, more preferably 1 to 7% by mass.
The F layer may be formed only on one side of the metal foil, or may be formed on both sides of the metal foil. When the F layers are formed on both sides of the metal foil, their composition and thickness are preferably the same from the viewpoint of suppressing warping of the laminate.
The dielectric constant of the F layer is preferably 2-3.5, more preferably 2-3. In this case, the laminate can be suitably used for printed circuit boards and the like that require a low dielectric constant.
The dielectric loss tangent of the F layer is preferably 0.003 or less, more preferably 0.002 or less. It is preferably a value measured by SPDR at a frequency of 10 GHz.

The thickness of the F layer is preferably 50 μm to 150 μm, more preferably 75 to 125 μm. Within this range, it is easy to balance the electrical properties and the suppression of warpage when the laminate is processed into a printed circuit board.
The water absorption rate of the F layer is preferably 0.1% or less, more preferably 0.08% or less, and even more preferably 0.05% or less.
The F layer may be a single layer or multiple layers. For example, a first F layer is formed on the surface of a metal foil using a powder dispersion containing a small amount of the F powder, inorganic filler, and elastomer contained in the layer-forming components, and the F powder contained in the layer-forming components, A second F layer may be formed on the surface of the first F layer using an F powder dispersion having a high amount of inorganic filler and elastomer. By such a method, it is possible to easily obtain a laminate having excellent adhesion to the metal foil and excellent physical properties due to the F powder, the inorganic filler and the elastomer.

The linear expansion coefficient of the laminate of the present invention is preferably 30 ppm/°C or less, more preferably 25 ppm/°C or less, and even more preferably 20 ppm/°C or less. In this case, it is possible to suitably prevent the laminate from warping.
The laminate of the present invention preferably has a warpage rate of 25% or less, more preferably 7% or less. In this case, the handling property when processing the laminate into a printed circuit board and the transmission characteristics of the resulting printed circuit board are excellent.
The dimensional change rate of the laminate is preferably ±1% or less, more preferably ±0.2% or less. In this case, it is easy to process the laminated body into a printed circuit board, and to make it multi-layered.
Moreover, the laminate of the present invention may contain additional layers made of other materials as long as the effects of the present invention are not impaired. Additional layers include polyimide layers and liquid crystalline polyester layers. Having these additional layers can significantly reduce the coefficient of linear expansion of the laminate. A specific layer structure includes metal foil/F layer/additional layer/F layer/metal foil.

Since the surface of the F layer of the laminate of the present invention has excellent adhesiveness, it can be easily and strongly adhered to another substrate.
For example, a metal foil may be laminated on the surface of the F layer to form a double-sided metal-clad laminate. In this case, a roll laminator comprising a pair of hot rolls or a double belt press in which a plurality of pairs of hot rolls are connected by a belt can be used to laminate the metal foil on the surface of the laminate. The lamination temperature is preferably 300°C to 400°C, more preferably 320°C to 380°C.
In this case, only the metal foil may be adhered to the laminate, or laminates having the same F layers or laminates having different F layers may be adhered. For example, if the laminates of the present invention having F layers with a thickness of 50 μm are arranged so that the F layers face each other and are thermocompressed, a laminate having metal foils on both sides of the F layers with a thickness of 100 μm (Double-sided metal-clad laminate) can be manufactured.
Furthermore, other substrates may be adhered to the laminate of the present invention.

Other substrates include a heat-resistant resin film, a prepreg that is a precursor of a fiber-reinforced resin plate, a laminate having a heat-resistant resin film layer, a laminate having a prepreg layer, and the like.
A prepreg is a sheet-like substrate obtained by impregnating a base material (tow, woven fabric, etc.) of reinforcing fibers (glass fiber, carbon fiber, etc.) with a thermosetting resin or thermoplastic resin.
The heat-resistant resin film is a film containing one or more heat-resistant resins, and may be a single-layer film or a multilayer film.
Examples of heat-resistant resins include polyimides, polyarylates, polysulfones, polyallylsulfones, aromatic polyamides, aromatic polyetheramides, polyphenylene sulfides, polyaryletherketones, polyamideimides, and liquid crystalline polyesters.

As a method of laminating another base material on the laminate of the present invention, a method of hot-pressing the laminate and another substrate can be mentioned.
When the other substrate is a prepreg, the pressing temperature is preferably below the melting point of the F polymer, more preferably 120 to 300.degree. When the other substrate is a heat-resistant resin film, the press temperature is preferably 310-400.degree.
It is particularly preferable to perform the heat pressing at a degree of vacuum of 20 kPa or less from the viewpoint of suppressing inclusion of air bubbles and suppressing deterioration due to oxidation.
Moreover, it is preferable to raise the temperature after the degree of vacuum is reached at the time of hot pressing. In this case, since another substrate is pressure-bonded before the F layer softens, that is, before a certain degree of fluidity occurs, air bubbles are less likely to occur.
The pressure in the hot press is preferably 0.2 to 10 MPa from the viewpoint of firmly adhering the F layer and the substrate while suppressing breakage of the substrate.

The laminate of the present invention has excellent dimensional stability and flexibility, and has an F layer with low water absorption. In addition, the F layer has excellent electrical properties (low dielectric constant, low dielectric loss tangent, etc.) because the properties of the F polymer are less likely to be impaired. Therefore, the laminate of the present invention is suitable for use in forming flexible printed circuit boards.
When used to form a flexible printed circuit board (hereinafter also referred to as "flexible printed circuit board application"), the laminate of the present invention preferably has the following physical properties.
That is, the peel strength of the metal foil to the F layer is preferably 8 N/cm or more, more preferably 12 N/cm or more, and even more preferably 16 N/cm or more. In this case, peeling of the pattern circuit from the F layer can be more reliably suppressed in the resulting flexible printed circuit board.

The heat deformability of the laminate is preferably 0.5% or less, more preferably 0.3% or less, and even more preferably 0.2% or less. In this case, the resulting flexible printed circuit board can have improved dimensional stability and reduced temperature dependence of electrical properties.
Further, the elastic modulus of the F layer is preferably 0.1 to 3 GPa, more preferably 0.2 to 2.5 GPa. In this case, since the laminate of the present invention has particularly excellent flexibility, flexible printed circuit boards can be produced under more free conditions. In addition, the elastic modulus of F layer means the tensile elastic modulus measured according to JISK7161.
Furthermore, since the F layer in the present invention contains a large amount of inorganic filler, it also has high thermal conductivity. Specifically, the thermal conductivity of the F layer is preferably 0.2 W/mK or more in the thickness direction and 0.3 W/mK or more in the surface direction. In this case, when the semiconductor chip is mounted on the flexible printed circuit board and actually used, the heat dissipation effect is excellent.

In the printed circuit board manufacturing method of the present invention, the metal foil of the laminate is processed to form a pattern circuit. Methods of processing the metal foil include an etching method and an electroplating method (semi-additive method (SAP method), modified semi-additive method (MSAP method), etc.).
After forming the pattern circuit, an interlayer insulating film may be formed on the pattern circuit, and a conductor circuit may be further formed on the interlayer insulating film. The interlayer insulating film may be formed from the powder dispersion of the present invention. Moreover, you may laminate|stack a solder resist or a cover-lay film on a pattern circuit. A solder resist or coverlay film may be formed with the powder dispersion of the present invention.
Since the printed circuit board manufactured in this way has the F layer with high bendability, it can be suitably used as a flexible printed circuit board.

Although the powder dispersion liquid, the method for manufacturing the laminate, and the method for manufacturing the laminate and the printed circuit board of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments.
For example, the dispersion liquid and the laminate of the present invention may be added to any other configuration in the configurations of the above-described embodiments, or may be replaced with any configuration that exhibits similar functions.
In addition, in the method for manufacturing a laminate and the method for manufacturing a printed circuit board of the present invention, in the configurations of the above-described embodiments, any other step for any purpose may be added, or any step that exhibits the same effect may be added. It may be replaced with a step.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
Various measurement methods and materials used are shown below.
<Bendability>
A test piece (5 mm × 5 mm) prepared by etching and removing the copper foil of the laminate with an aqueous ferric chloride solution was bent 180° under the condition of a curvature radius (300 µm), and a load was applied from above (50 mN, 1 minute). After applying the stress, the bending was returned, and the appearance of the test piece was evaluated according to the following criteria.
◯ (Good): No abnormality in appearance is observed at the crease portion.
(triangle|delta) (acceptable): Whitening was seen in the crease part.
x (impossible): broken at the crease.

<Linear expansion coefficient>
A test piece (3 mm × 10 mm) prepared by etching and removing the copper foil of the laminate with an aqueous ferric chloride solution was analyzed using a thermomechanical analyzer (manufactured by SII Nanotechnology, trade name: TMA/SS6100). After raising the temperature from 0°C to 400°C at 10°C/min, cooling to 10°C at 40°C/min, and then raising the temperature from 10°C to 200°C at 10°C/min. bottom. The measurement load was 29.4 mN, and the measurement atmosphere was an air atmosphere.

<Water absorption rate>
The water absorption rate was measured according to the method of JIS K 7209:2000A.
A test piece (10 cm×10 cm) prepared by removing the copper foil of the laminate by etching with an aqueous ferric chloride solution was dried at 50° C. for 24 hours and cooled in a desiccator. The mass of the test piece at this point was taken as the mass of the test piece before immersion.
Next, the test piece was immersed in pure water at 23° C. for 24 hours. After removing the test piece from the pure water and quickly wiping off the moisture on the surface, the mass measured within 1 minute was taken as the post-immersion mass of the test piece. The rate of change in mass of the test piece before and after immersion was taken as the water absorption rate of the laminate.

<Dielectric loss tangent>
It was measured by the SPDR method at a frequency of 10 GHz under an environment of 23° C.±2° C. and 50±5% RH.

[F Powder]
F powder 1: A polymer having an acid anhydride group containing 97.9 mol%, 0.1 mol% and 2.0 mol% of TFE units, NAH units and PPVE units in this order (melting temperature: 300°C) Powder (D50: 1.7 μm, D90: 3.8 μm)
F powder-2: A powder (D50: 18.5 μm) composed of a polymer having no functional group (melting temperature: 305° C.) containing 97.5 mol % and 2.5 mol % of TFE units and NAH units in this order.

[Dispersant]
Dispersant 1: (meth)acrylate polymer having a perfluoroalkyl group, a hydroxyl group and a polyoxyalkylene group (fluorine content: 35% by mass, hydroxyl value: 19 mgKOH/g)
[Metal foil]
Copper foil 1: "CF-T4X-SV-18" manufactured by Fukuda Metal Foil and Powder Co., Ltd., thickness: 18 μm, surface ten-point average roughness 0.6 μm)

[Inorganic filler]
Filler 1: Spherical silica (manufactured by Denka, "FB-7SDC", average particle size: 5 μm, aspect ratio: 1)
Filler 2: powdery magnesium oxide (manufactured by Ube Materials Co., Ltd., vapor phase method high purity ultrafine powder grade, average particle size: 0.3 μm, aspect ratio: 1)
Filler 3: Scaly boron nitride (manufactured by Showa Denko Co., Ltd., "UHP-2", average particle size: 11 μm, aspect ratio: 4)

[Elastomer]
Elastomer 1: Amine-modified styrene-based elastomer (SEBS, manufactured by Asahi Kasei Corporation, "Tuftec MP10")
Elastomer 2: Fluorine-based elastomer (FEPM, manufactured by AGC, "AFRAS 150CS")

[Example 1] Production example of powder dispersion [Example 1-1] Production example of powder dispersion 1 In a pot, 48 parts by mass of cyclohexanone and 2 parts by mass of dispersant 1 are mixed, and 15 parts by mass are mixed. F powder 1, 1.5 parts by mass of elastomer 1, and 33.5 parts by mass of filler 1 were added in order, and the pot was rolled to prepare powder dispersion 1.
[Examples 1-2 to 1-9] Production Examples of Dispersions 2 to 9 Powder dispersions 2 to 8 were produced in the same manner as in Example 1-1, except that the materials used and their mixing ratios were changed. . Powder dispersions 7 to 9 in Examples 1-7 to 1-9 correspond to comparative examples.
The components of each powder dispersion are summarized in Table 1 below.

なお、他の成分におけるエポキシ樹脂１とは、芳香族系エポキシ樹脂と硬化剤とを含む硬化性組成物であり、例１－７に記載するエポキシ樹脂１の成分量は、層形成成分としての量である。

Epoxy resin 1 in other components is a curable composition containing an aromatic epoxy resin and a curing agent, and the component amount of epoxy resin 1 described in Example 1-7 is quantity.

[Example 2] Production evaluation example of laminate [Example 2-1] Production example of laminate 1 Dispersion 1 was applied to copper foil 1 by a die coating method to form a liquid coating. Then, this liquid coating was passed through a drying oven at 120° C. for 5 minutes and dried by heating to obtain a dry coating. After that, the dried film was baked by heating it at 380° C. for 10 minutes in a far-infrared furnace under a nitrogen atmosphere. As a result, a laminate 1 (resin-coated copper foil) in which an F layer having a thickness of 100 μm was formed on the surface of the copper foil 1 was obtained.
[Examples 2-2 to 2-9] Production Examples of Laminates 2 to 9 Laminates 2 to 9 were produced in the same manner as in Example 2-1, except that the type of dispersion liquid was changed.
The bending ratio, coefficient of linear expansion, water absorption and dielectric loss tangent of each laminate were evaluated.
These results are summarized in Table 2 below.

Since the laminate of the present invention has excellent dimensional stability and flexibility and has a low water absorption layer, it can be processed into antenna parts, printed circuit boards (particularly flexible printed circuit boards), aircraft parts, automobile parts, and the like. can be used

Claims (14)

A layer-forming component containing a powder of a tetrafluoroethylene-based polymer having a melting temperature of 140 to 320° C. , an inorganic filler, and an elastomer, and a solvent, wherein the tetrafluoroethylene-based polymer and the inorganic filler account for the layer-forming components. is 75 % by mass or more, and the ratio by mass of the amount of the inorganic filler to the amount of the tetrafluoroethylene-based polymer contained in the layer-forming component is greater than 1.25. 2. The powder dispersion according to claim 1, wherein the ratio by mass of the amount of said elastomer to the amount of said tetrafluoroethylene-based polymer contained in said layer-forming component is 0.05 or more. 3. The powder dispersion according to claim 1, further comprising a polymer having polyfluoroalkyl or polyfluoroalkenyl groups and hydroxyl or polyoxyalkylene groups. Furthermore, any one of claims 1 to 3, comprising a polymer having a polyfluoroalkyl group or a polyfluoroalkenyl group and a hydroxyl group, having a fluorine content of 10 to 50% by mass and a hydroxyl value of 10 to 100 mg/KOH. Powder dispersion according to item 1. Powder dispersion according to any one of claims 1 to 4, wherein the solvent is a ketone, amide or ester. The powder dispersion according to any one of claims 1 to 5, wherein the elastomer comprises at least one thermoplastic elastomer selected from the group consisting of butylene/isoprene/butadiene elastomers, styrene elastomers and fluorine elastomers. liquid. The powder dispersion according to any one of claims 1 to 6 , having a viscosity at 25°C of 10 to 10000 mPa·s. The powder dispersion according to any one of claims 1 to 7 , which is used for forming flexible printed circuit boards. The powder dispersion according to any one of claims 1 to 8 is applied to the surface of a metal foil and heated to form the metal foil and the tetrafluoroethylene system formed on the surface of the metal foil. A method for producing a laminate, comprising obtaining a laminate having a layer containing a polymer, the inorganic filler, and the elastomer. 10. The manufacturing method according to claim 9 , wherein the layer has a thickness of 50-150 μm. A metal foil, and a layer formed on the surface of the metal foil and containing a tetrafluoroethylene-based polymer having a melting temperature of 140 to 320° C. , an inorganic filler, and an elastomer, wherein the tetrafluoroethylene-based polymer occupies the layer. and the inorganic filler in a total ratio of 75 % by mass or more, and the ratio by mass of the amount of the inorganic filler to the amount of the tetrafluoroethylene-based polymer contained in the layer is greater than 1.25. laminate. 12. The laminate of claim 11 , used to form flexible printed circuit boards. 13. A method of manufacturing a printed circuit board, comprising processing the metal foil of the laminate according to claim 11 or 12 to form a pattern circuit. 14. The manufacturing method according to claim 13 , wherein the printed circuit board is a flexible printed circuit board.