JPH05301974A - Particulate-filled composite film and its production - Google Patents

Abstract

PURPOSE: To obtain the title film excellent in physical properties and electrical properties and useful for e.g. laminated electrical circuit boards by casting a casting composition layer containing a specified amount of a polymer and a specified amount of a filler on a substrate and solidifying the composition.

CONSTITUTION: A dispersion of a particulate filler selected from the group consisting of glass particles, ceramic particles, metallic particles ore particles and synthetic polymer particles in a carrier liquid such as water is mixed with a polymer such as a polytetrafluoroethylene to produce a casting composition containing a polymer and a filler in relative amounts effective for obtaining a composite film containing at least 15 vol.% or above filler particles, the casting composition layer is cast on a substrate, and the cast layer is solidified to form a particulate-filled polymer matrix composite film being the purpose film.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a particulate filled polymer matrix composite.
matrix composit materials) and its manufacturing method, in particular thin films of highly filled polymer matrix composites.

[0002]

Laminated electrical circuit boards having a conductive layer supported on a dielectric fluoropolymer matrix composite layer are known. There continues to be a trend towards higher circuit densities, but highly packed (high) with substantially uniform microstructure.
A very thin (eg, less than about 1.0 mil) film of a ly filled) fluoropolymer matrix composite substrate material is desirable because it can further reduce the size of electrical circuits. It is technically and economically difficult to produce such materials by known methods.

Fluoropolymer and particulate-filled fluoropolymer matrix composite films are produced by the known papermaking, skiving, casting, melt extrusion and paste extrusion and rolling processes.

Films made by the papermaking process require fiber reinforcement and are limited to thicknesses of about 2 mils or more.

Producing a thin, high quality, highly filled fluoropolymer matrix film by milling is resistant to wear of the milling blade by filler particles and to the milling blade. It is very difficult because the film containing the filler particles tears.

The amount of filler in films made by known casting methods is limited to less than about 15% by volume.

The production of fluoropolymers by melt extrusion is cumbersome because the melt viscosity of pure fluoropolymers is high. Polyvinylidene fluoride (PVF ₂ ) and polychlorotrifluoroethylene (PCTFE) can be melt extruded only within a narrow processing window. Polyvinyl fluoride (PV
F) Films are heat labile and cannot be produced by melt extrusion. Polytetrafluoroethylene (PTFE)
Cannot be melt extruded because its melt viscosity is so high.
Fluorocopolymers with low melt viscosities and low melt viscosities at extrusion temperatures [eg copolymers of tetrafluoroethylene with hexafluoropropylene (FEP) or ethylene, CTFE with vinylidene fluoride or hexafluoropropylene] Is known.

The incorporation of fillers further complicates melt extrusion of fluoropolymers. In the presence of certain fillers, especially at high filler loading levels, the melt processability of melt-extrudable fluoropolymers depends on the melt viscosity due to the presence of fillers or the filler-catalyzed thermal decomposition of the polymer matrix. Because it becomes higher, it decreases rapidly.

A method of making highly filled PTFE composites exhibiting excellent physical and electrical properties by paste extrusion and rolling is described in US Pat.
No. 4,849,284 (DJ Arthur, JCMosko, CSJackson and
GRTraut, “ELECTRICAL SUBSTRATE MATERIAL”). However, producing thin (ie, less than 2 mil), highly filled (ie, greater than about 40%) fluoropolymer matrix composite films by paste extrusion and roll extrusion is very technically and economically Have difficulty.

What is needed in the art is a method that overcomes the deficiencies of known processing methods.

[0011]

SUMMARY OF THE INVENTION A particulate filled fluoropolymer matrix composite article is disclosed. The article comprises a fluoropolymer matrix and up to about 95% by volume filler particles dispersed throughout the matrix having a maximum equivalent spherical diameter of less than about 10 microns.

In another embodiment, the particulate filled fluoropolymer matrix composite article has neither a fluoropolymer matrix nor filler particles having a single linear dimension greater than about 10 microns. , About 95 volumes dispersed throughout the matrix
% Of filler particles.

In a preferred embodiment, the particulate filled fluoropolymer matrix composite film comprises a non-fibrillated fluoropolymer matrix and about 15 dispersed throughout the matrix.
It is composed of filler particles of not less than volume%. This film is
It has no macroscopically visible pinholes or crevices and is less than about 2 mils thick.

Disclosed is a porous fluoropolymer film consisting of a non-fibrillated fluoropolymer matrix having a porosity of greater than or equal to about 15% by volume and a thickness of less than about 2 mils.

A method of making a polymer matrix composite film with particulate filler is disclosed. The method comprises mixing a polymer and a dispersion of particulate filler in a carrier liquid to give a volume of 15% by volume.
Making a casting composition containing a relative amount of polymer and filler effective to obtain a film having the above filler, cast a casting composition layer on the substrate,
The casting layer then solidifies to form a particulate filled polymer matrix composite film.

A casting composition is also disclosed. The casting composition also comprises a mixture of carrier liquid, polymer matrix material and particles of filler material.

[0017]

DETAILED DESCRIPTION Suitable fluoropolymer matrix materials include fluorinated homopolymers [eg, polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE)] and fluorinated copolymers [eg, tetrafluoroethylene, Copolymers of monomers selected from the group consisting of hexafluoropropylene and perfluoroalkyl vinyl ethers; Copolymers of tetrafluoroethylene with monomers selected from the group consisting of vinylidene fluoride, vinyl fluoride and ethylene; and chlorotrifluoro Copolymers of ethylene with a monomer selected from the group consisting of hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, vinyl fluoride and ethylene]
Is mentioned. Blends of the above fluoropolymers with terpolymers formed from the above monomers are also suitable as fluoropolymer matrix materials of the present invention.

Alternatively, the polymer matrix material of the present invention may include a thermoplastic or thermosetting polymer other than a fluoropolymer. Suitable alternative polymer matrices include, for example, polyolefins, polyimides, epoxy resins and cyanate esters. Specific examples of suitable polymeric matrix materials include polyethylene, polymethylpentene and polybutadiene.

The particulate filler material of the present invention may include any organic or inorganic particulate material. The terms "granular" and "particles" as used herein shall include fibers. Suitable inorganic filler materials include, for example:
Examples include glass particles, ceramic particles, metal particles, carbon particles and mineral particles. Specific examples of suitable particles include:
Examples include glass beads, glass microspheres, glass fibers, silica particles, carbon black, titanium dioxide particles and barium titanate particles. Silica particles, especially amorphous fused silica particles and silica particles produced by the sol-gel method, and glass particles are preferred filler particles for applications such as dielectric layers of laminated electrical circuits requiring a low dielectric constant.

Specific examples of suitable polymeric particulate fillers include polymethylmethacrylate particles, polystyrene particles and polyimide particles. Suitable polymer particles include, for example, LARC-TP1 (Rogers, Corp.) and P-84 (L
enzing).

The shape of the filler particles, the size of the filler particles and the size distribution of the filler particles are important parameters for the properties of the granular filled composite product of the present invention.

In a preferred embodiment of the present invention, all particles of the particulate filler are of equal volume sphere diameter less than about 10 microns (μm). As used herein, the term "equivalent spherical diameter" of filler particles refers to the diameter of a sphere that occupies the same volume as occupied by the filler particles.

In another preferred embodiment of the present invention, each filler particle does not exhibit a single linear dimension greater than about 10 microns.

In applications where ultrathin films and substantially homogeneous microstructures are important properties of the film, it is preferred that all particles of particulate filler exhibit an equivalent spherical diameter of less than about 5 microns. .. Alternatively, it is preferred that not all particles of the particulate filler exhibit a single linear dimension greater than about 5 microns.

In the preferred embodiment of the invention, each filler particle is substantially spherical. The use of spherical filler particles results in improved processing properties due to the minimal filler surface area for a given particle size and amount of filler. In addition, spherical particles can impart isotropic properties to the film because the spherical particles do not orient during processing.

In a preferred embodiment of the invention, the filler particles of the film are of uniform size. The use of monodisperse fillers (ie all filler particles are substantially the same size) results in a more homogeneous film having substantially uniform properties.

In a particularly preferred embodiment of the present invention, the filler particles consist of spherical silica particles of substantially the same size (ie all particles are within ± 10% of the nominal particle size). GELSIL ^R [R;. Geltech, Inc manufactured, 1 micron sphere size (+/- 10%), density of 2.2 g / cm ^2, hard without aggregates)] known pure silica powder as the embodiment of the present invention Have been found to be particularly suitable for use in.

The particulate filler material may be surface treated to improve the moisture barrier and mechanical properties of the composite film of the present invention.

The hydrophobic coating of the present invention can be comprised of any thermally stable, low surface energy coating material that improves the moisture barrier properties of the composite material of the present invention. Suitable coating materials include conventional silane coatings, titanate coatings and zirconate coatings. Preferred silane coatings include phenyltrimethoxysilane, phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrodecyl) -1-triethoxy. Examples include silane and mixtures thereof. Other examples of suitable fluorinated silane compounds are described in U.S. Patent Application No. 279,474 (1), herein incorporated by reference.
Filed December 2, 988, DJ Arthur and GSSwei, “FLUOR
OPOLYMERCOMPOSITE ”). Suitable titanate coatings include neopentyl (diallyl) oxytrineodecanoyl titanate, neopentyl (diallyl) oxytri (dioctyl) phosphate titanate. Suitable zirconate coatings include neopentyl. (Diallyl) oxytri (dioctyl) pyrophosphate zirconate and neopentyl (diallyl) oxytri (N-ethylenediamino) ethyl zirconate. Other examples of suitable titanate and zirconate coatings are herein incorporated by reference. Included US Patent Application No. 483,501 (filed February 21, 1990, DJ Arthur and GSSwei, “CE
RAMIC FLUOROPOLYMER ”).

The hydrophobic coating is used in an amount effective to render the surface of the filler particles hydrophobic and compatible with the matrix material. The amount of coating relative to the amount of inorganic particles coated depends on the surface area coated and the density of the inorganic particles. The coated inorganic particles of the present invention preferably vary from about 0.5 parts by weight (pbw) hydrophobic coating: 100 pbw inorganic particles to about 25 pbw hydrophobic coating: 100 pbw inorganic particles.

The polymeric matrix material of the present invention is mixed with a first carrier liquid. This mixture is a dispersion of polymer particles in a first carrier liquid, ie an emulsion or suspension of droplets of a polymer or a monomeric or oligomeric precursor of a polymer in a first carrier liquid, or a first dispersion of a polymer. It may consist of a solution of a carrier liquid.

The first carrier liquid is selected based on the particular polymeric matrix material and the form in which the polymeric matrix material is incorporated into the casting composition of the present invention. When it is preferable to introduce the polymeric material as a solution, the solvent for the particular polymeric matrix material is selected as the carrier liquid [eg, N-methylpyrrolidone (NMP) is a suitable carrier liquid for the solution of the polyimide]. When it is preferred to introduce the polymer matrix material as a dispersion, a suitable carrier liquid is a liquid in which the matrix material is insoluble (e.g., water is a suitable carrier liquid for dispersions of PTFE particles, and polyamic acid It is a suitable carrier liquid for emulsions or emulsions of butadiene monomers).

The fluoropolymer matrix material is preferably introduced as an aqueous dispersion. DuPont Tefl
The aqueous dispersion of PTFE, known as on ^R TE 30®, has been found to be particularly suitable for use in the examples of the present invention.

The particulate filler dispersion of the present invention is a suitable second carrier liquid (ie, liquid in which the filler is insoluble) dispersion. The second carrier liquid may be the same liquid as the first carrier liquid, or a liquid other than the first carrier liquid that is miscible with the first carrier liquid. For example, when the first carrier liquid is water, the second carrier liquid may consist of water or alcohol. The second carrier liquid is preferably water.

The dispersion of filler particles may include an effective amount of a surfactant to modify the surface tension of the second carrier liquid so that the second carrier liquid can wet the filler particles.
Suitable surfactant compounds include ionic and non-ionic surfactants. Triton X-1
00 (Rohm & Haas) has been found to be a suitable surfactant for use in aqueous filler dispersions.

The filler dispersion contains about 10% by volume of filler particles (v
ol%) to about 50% by volume, surfactant about 0.1% to about 10% by volume
And the balance preferably consists of the second carrier liquid.

A mixture of polymer matrix material and a first carrier liquid is mixed with a second dispersion of filler particles in a carrier liquid to form the casting composition of the present invention. The casting composition comprises about 10% to about 60% by volume of mixed polymer matrix material and filler particles, about 40% by volume of a mixture of a first carrier liquid and a second carrier liquid.
% To about 90% by volume. For the amount of polymer matrix material and filler particles mixed, the filler particles
It may comprise from 15% to about 95% by volume. For the amount of polymer matrix material and filler particles mixed, the filler particles should be approximately
Preferably, it comprises from 30% to about 70% by volume. It is most preferred to include from about 40% by volume to about 65% by volume of filler particles, based on the combined amount of polymer matrix material and filler particles.

The viscosity of the casting composition of the present invention is
To prevent the separation (ie, settling or flotation) of filler particles from the casting composition and to provide a casting composition having a viscosity compatible with conventional casting equipment, a particular carrier liquid or carrier liquid mixture may be used. It is adjusted by adding a suitable viscosity modifier selected on the basis of its compatibility. Conventional thickeners are suitable and are selected based on the carrier liquid selected. Conventional viscosity modifiers suitable for use in aqueous casting compositions include, for example, polyacrylic acid compounds,
Included are vegetable gums and cellulose-based compounds.
Specific examples of suitable viscosity modifiers include polyacrylic acid,
Mention may be made of methyl cellulose, polyethylene oxide, guar gum, locust bean gum, sodium carboxymethyl cellulose, sodium alginate and tragacanth gum.

The minimum viscosity of a viscosity adjusted casting composition depends on the time period of interes.
t) the theoretical terminal velocity (ie, filler separation rate) that gives a casting composition that is stable within (ie, mixing the casting composition and casting from the composition to solidifying the film). Stokes' law based on the size and density of the filler particles, which gives: v = gD _p ² (ρ _p −ρ _L ) / 18 μ, where v = terminal velocity of particles, g = gravitational constant, D _p = Particle size, ρ _p = particle density, ρ _L = liquid density, and μ = liquid viscosity). For example, substituting by the above relationship, an aqueous solution having a viscosity of 10,000 cp has a diameter of 1
For silica particles with micron (density = 2.2 g / cm ³ ), the theoretical terminal velocity is 6.5 × 10 ⁻¹⁰ cm / s. The viscosity of the viscosity adjusted casting composition may be even higher (above the minimum viscosity) in the application, depending on the casting method chosen for the casting composition. For example, for weighing rod casting, about 300 cp to about 1000 c
A viscosity of p is preferred.

The viscosity adjusted casting composition has a viscosity of about
It preferably exhibits a viscosity of 10 cp to about 100,000 cp. The viscosity adjusted casting composition has from about 100 cp to about 10,000 cp.
Most preferably, it has a viscosity of.

Alternatively, the viscosity modifier may be omitted if the viscosity of the carrier liquid is sufficient to obtain a casting composition that does not separate during the period of interest. Especially for very small particles (eg particles having an equivalent spherical diameter of less than 0.1 micron) it is not necessary to use a viscosity modifier.

The layer of viscosity adjusted casting composition is cast onto the substrate by conventional methods such as dip coating, reverse roll coating, knife-over-roll, knife-over-plate and metering rod coating.

Suitable substrate materials include, for example, metal films, polymer films or ceramic films. Specific examples of suitable substrates include stainless steel foils, polyimide films, polyester films and fluoropolymer films.

The carrier liquid and processing aids (ie surfactants and viscosity modifiers) are removed from the cast layer, for example by evaporation and / or pyrolysis, to solidify the film of polymeric matrix material and particulate filler. (Consolidate)
To do. It is preferred to heat the particulate filled polymer matrix composite film of the present invention to evaporate the carrier liquid.

The composition of the solidified film corresponds to the mixing amount of polymer matrix material and filler particles described for the casting composition. That is, the film comprises 15% to about 95% by volume filler particles and about 5% to 85% by volume matrix material, preferably about 30% to about 70% filler particles.
% And about 30% to about 70% by volume of matrix material, most preferably about 40% to about 65% by volume filler particles and about 35% to about 60% by volume matrix material particles.

The solidified film of polymer matrix material and particulate filler may be further heated (eg, by sintering a thermoplastic matrix material, or by curing and / or post-curing a thermosetting matrix material) of the film. Physical properties can be modified.

The method of the present invention allows economical production of films having a thickness of less than about 2 mils, and even less than about 1 mil. In this specification, the thickness of the film is “mil” (1 m
il equals 0.001 inches).

The method of the present invention can produce thin films without deforming the film (eg, rolling or expanding the film) without fibrillating the matrix material properties as with expanded films. Also, fluoropolymer matrix films can be made without the risk of tearing or pinholes in the film.

When making a porous film, the filler material is removed from the solidified film. The method of removal depends on the choice of filler material. If the matrix material is dispersed in a matrix material that exhibits much higher heat resistance than the filler material (eg, polymethylmethacrylate filler in a PTFE matrix), the filler material will solidify and sinter. It can be removed by heating in stages. Alternatively, the filler material may be dissolved in a liquid in which the filler is soluble but the matrix material is insoluble. Removing the filler material from the fluorinated polymer matrix to form a porous fluoropolymer film is described in U.S. Pat. No. 4,987,274 (TL Milliller, WR, incorporated herein by reference).
Zelanis, GA Woerner and AF Horn III, “COAXIAL CAB
LE INSULATION AND COAXIAL CABLE MADE THEREWITH ”)
It is described in.

The fluoropolymer matrix of the thin porous fluoropolymer film of the present invention has an expanded porosity.
It should be noted that it does not exhibit the fibrillar structural properties of the PTFE film.

The substrate and the solidified film may be used in combination as a laminated composite material or a substrate for the next composite layer. Alternatively, the substrate may be removed from the film. The substrate is, for example, dissolved in a solvent, and by a chemical reaction,
Alternatively, it can be removed by pyrolysis, or the substrate can be removed for reusability (eg, debonding the interfacial adhesion between the cast film and the substrate).

The solidified film may be used alone as described below or as a substrate for further casting another layer of the casting composition to make a multilayer film.

The thin, particulate-filled fluoropolymer matrix composite film of the present invention has a wide variety of useful applications.

A laminated circuit board manufactured by the method of the present invention is shown in FIG. The substrate comprises a conductive layer 2 laminated with a fluoropolymer composite layer 4 containing a granular filler. Figure 2
The laminated substrate shown in can be manufactured by casting and solidifying layer 4 on the layer of conductive film 2.

As mentioned above, the shape and size distribution of the filler particles is very important in some applications.

The thickness of the film is very important in applications where the particulate filled film is used as a dielectric substrate for high density laminated electrical circuits. As the dimensions of the circuit become smaller, it is preferable to make the thickness of the dielectric layer correspondingly smaller, thereby preserving the impedance characteristics of the circuit.

Usually, the longest characteristic dimension of filler particles is
It is preferably significantly smaller (eg by a factor of 10) than the thickness of the particulate filled film to prevent particle bridging between the surfaces of the film. As the desired film thickness decreases, it becomes increasingly difficult to meet the criteria.

Another mode of high circuit density (outgrowt
h) is shown in FIGS. 3 and 4. A portion of a conventional laminated circuit 6 comprises a conductive layer 8 encapsulated within dielectric layers 10,12. Conductive through holes (or “vias”) are defined by conductive sleeve 14. The conductive sleeve 14 has a dielectric layer 10,
It is separated from the conductive layer 8 by an insulating sleeve region 16 of dielectric material formed by melting the ends of 12. As circuit density increases, it is preferable to reduce the size of conductive through holes. As the distance between the conductive sleeve 14 and the conductive layer 8 becomes smaller, the size of the filler becomes
It must be correspondingly small to prevent bridging of filler particles between the conductive sleeve 14 and the conductive layer 8.

Another aspect of increasing circuit density and decreasing through-hole hole diameter requires the opening of smaller holes. As the through-hole pore size decreases, the filler particle size becomes an important factor in pore performance. Laser drilling a particulate filled fluoropolymer matrix film is described in US Pat. No. 4,915,981 (RTTraskos, CA Fleischer, CA Barton and DB Nodd, incorporated herein by reference).
in, "METHOD OF LASER DRILLING FLUOROPOLYMER MATERI
ALS "). Laser drilling is effective in removing the exact amount of matrix material and causes the entire agglomerate of filler particles to be ejected from the drilled holes. The use of filler particles results in high performance, ie more precisely defined, laser drilled small diameter holes.

FIG. 5 shows a portion of a laminated electrical circuit 16 that includes a bondply 18 sandwiched between a pair of laminated circuit layers each comprising a conductive layer 22 supported on a dielectric layer 20. Show. The casting method of the present invention can be carried out with a lower temperature melting fluoropolymer matrix material (eg, FEP) to produce a very thin, highly filled adhesive layer for use in laminated electrical circuits. It Being able to produce a highly filled fluoropolymer polymer matrix adhesive layer gives similar electrical properties to the substrate layer to be adhered, and being able to produce a very thin adhesive layer results in an adhesive layer with improved dimensional stability in laminated circuits. The adverse effects can be minimized.

The ability to produce very thin, highly filler-filled fluoropolymer films with regular microstructures, in the reference system provided by the included short-wave radiation, is intended for specific applications. It is also advantageous as a circuit board material for "mm-wave" applications where ultrathin films with physical and electrical properties, which are considered to be substantially uniform, are required.

The inorganic-filled matrix composite layer may be cast on a polyimide film to produce a composite film suitable for use in flex circuit applications. Flexible circuits comprising a microglass reinforced fluoropolymer matrix composite layer sandwiched between a polyimide film and a copper conductive pattern are described in U.S. Pat.No. 4,634,631 (S. Gazit), which is incorporated herein by reference. And CA Fleisher, “FLEXIBLE CIRCUIT LAMI
NATE AND METHOD OF MAKING THE SAME ”).

The porous films produced by the method of the present invention have a wide range of useful applications such as filtration membranes, breathable fabrics and the like.

[0064]

Example 1 A thin film of a particulate filled fluoropolymer matrix composite was prepared by the method of the present invention.

The filler particles were pretreated with a silane coupling agent. A mixture of 6 parts by weight of coated silica particles, 4 parts of water and 0.05 parts of a surfactant (Triton X-100) was ball milled for 12 hours to form an aqueous filler dispersion.

An aqueous dispersion of 6 parts by weight of fluoropolymer particles in 4 parts by weight of water was mixed with a relative amount of the aqueous filler dispersion suitable to obtain the filler amounts shown in Table 1 below.

The viscosity of the aqueous dispersion of polymer and filler is
Sufficient polyacrylic acid, viscosity modifier (Acrysol ASE 7
5, Rohm & Haas) to adjust the viscosity to 1
A 000 cp casting composition was produced.

The viscosity adjusted casting composition was cast onto a 2 mil thick stainless steel foil using a laboratory scale knife-over-plate coater. The cast film was dried at 550 ° F for 1 hour and sintered at 700 ° for 10 minutes.

The matrix material, filler material, coating material, coating amount (expressed as weight percentage of filler particles) and film composition (% coated filler volume /% matrix material volume) of a number of sample film compositions are shown in Table 1. Shown in.

The absorption of water (immersion in water at 50 ° C. for 24 hours) and the specific gravity of the sample film compositions 1 and 4 were measured, and Table 1
Displayed on.

[0071]

[Table 1]

The tensile properties of the sample film of composition 1 were measured. The film has a tensile strength of 0.731 kpsi and an elongation at break of 16
The value was 7.4% and the tensile modulus was 4.62 kpsi.

A micrograph of a cross-sectional view of a film of composition 4 is shown in the figure.

Example 2 A porous thin film was prepared by the method described in Example 1 using polymethylmethacrylate particles of nominal size 0.2 micron as the filler material, 1.0 mil thickness with a filler content of 60% by volume. Sano film was manufactured. 60% of polymethylmethacrylate particles are thermally decomposed during the solidification and sintering process.
A porous PTFE film having a void volume of was produced.

Example 3 The illustrated casting composition was continuously cast onto a substrate using a # 21 Mayer rod. This film was heated at 250 ° C. to be solidified. Film composition, substrate,
The coating speed and film thickness are shown in Table 2.

[0076]

[Table 2]

The films described above were of high quality and were free of macroscopic defects such as pinholes, fish eyes and tears.

Example 4 A filled fluoropolymer film was continuously applied to Myla
Cast onto r, Kapton and PTFE substrates and solidified in an in-line oven in two zones (set at 150 ° C and 250 ° C respectively).

To obtain the relative amounts of fluoropolymer and filler particles shown in Table 3, an aqueous fluoropolymer dispersion was mixed with an aqueous dispersion of coated filler particles to form a casting composition. Table 3 shows the matrix material, filler material, coating, surfactant, viscosity modifier, pH and viscosity of each cast film composition. The amounts of polymer matrix material, filler and surfactant are expressed in parts, the coating amount is expressed as a weight percentage of filler particles, and the amount of viscosity modifier is expressed as a weight percentage of the total casting composition.

[0080]

[Table 3]

The number of compositions, substrate, coating speed (feet / ft) of the film cast using a pan fed on a knife-over-roll machine as well as the film cast using a nip fed on a three roll reversal coating machine. Min; fpm), oven temperature (first zone / second zone) and film thickness are shown in Tables 4 and 5, respectively.

[0082]

[Table 4]

[0083]

[Table 5]

The above cast films using knife-over-roll and reversal rolls were of high quality and were free of macroscopic defects such as pinholes, fish eyes and tears.

Although a preferred embodiment has been shown and described,
Various modifications and substitutions can be considered without departing from the spirit and scope of the present invention. Therefore, it should be understood that this aspect is described merely as an illustration of the present invention and not as a limitation of the present invention.

[Brief description of drawings]

FIG. 1 is a micrograph showing a particle structure of a cross section of a polymer matrix composite film containing a granular filler of the present invention.

FIG. 2 is a diagram showing a laminated circuit board manufactured by the method of the present invention.

FIG. 3 is a view showing a cross section of a conductive hole that connects layers in a portion of a laminated electric circuit.

4 is a diagram showing a cross section taken along line 4-4 of FIG.

FIG. 5 is a view showing a cross section of a part of a laminated electric circuit.

[Explanation of symbols]

 2 Conductive Layer 4 Fluoropolymer Composite Layer Filled with Particles 6 Conventional Laminated Circuit 8 Conductive Layer 10, 12 Dielectric Layer 14 Conductive Sleeve 18 Adhesive Layer 20 Dielectric Layer 22 Conductive Layer

Claims (69)

[Claims] 1. A relative amount of polymer and filler effective to obtain a composite film having 15% by volume or more of filler particles by mixing a dispersion of a particulate filler in a carrier liquid with the polymer. A particulate filled polymer matrix composite film comprising: producing a casting composition, casting a casting composition layer on a substrate, and then solidifying the cast layer to form a particulate filled polymer matrix composite film. Manufacturing method. 2. The method according to claim 1, wherein the carrier liquid comprises water. 3. The method of claim 1, wherein the polymer comprises a fluoropolymer. 4. The method according to claim 3, wherein the fluoropolymer comprises polytetrafluoroethylene. 5. The method of claim 1, wherein the filler particles comprise inorganic particles, organic particles or mixtures thereof. 6. The method of claim 5, wherein the filler particles comprise inorganic particles selected from the group consisting of glass particles, ceramic particles, metal particles and mineral particles. 7. The method of claim 5, wherein the filler particles comprise organic particles selected from the group consisting of synthetic polymer particles. 8. The method of claim 1, wherein the filler particles comprise coated inorganic filler particles comprising an inorganic core and a coating layer surrounding the core. 9. The method according to claim 8, wherein the coating layer is selected from the group of silane coatings, zirconate coatings and titanate coatings. 10. The method of claim 1, wherein the filler particles have a maximum isometric sphere diameter of less than about 10 microns. 11. The method of claim 1, wherein there are no filler particles having a single linear dimension greater than 10 microns. 12. The method of claim 1, wherein each filler particle is spherical. 13. The method of claim 1, wherein all filler particles are of substantially the same size. 14. The mixing step comprises mixing a first dispersion of polymer particles in a carrier liquid and a second dispersion of particulate filler in a carrier liquid, the carrier liquid of the casting composition comprising: The method of claim 1 comprising a mixture of first and second carrier liquids. 15. The method of claim 1 further comprising adding a surfactant to the carrier liquid to modify the surface tension of the carrier liquid and wetting the filler particles with the carrier liquid. 16. The method of claim 15, wherein the surfactant is selected from the group consisting of ionic surfactants and non-ionic surfactants. 17. The method of claim 1, further comprising adjusting the viscosity of the casting composition to prevent the particulate filler from the composition from separating. 18. The method of claim 17, wherein the viscosity is adjusted by adding an effective amount of a viscosity modifier selected from the group consisting of polyacrylic acid, vegetable gums and cellulose-based compounds. 19. The viscosity adjusted casting composition exhibits a viscosity in the range of about 100 cp to about 10,000 cp.
7. The method according to 7. 20. The method of claim 1, wherein the layer is cast by dispersion coating, knife-over-roll, roll-roll coating, reverse roll coating or metering and rod coating. 21. The method according to claim 1, wherein the substrate comprises a metal foil, a polymer film or a ceramic film. 22. The method of claim 1, further comprising removing the substrate from the film subsequent to the solidifying step. 23. The method of claim 15 wherein the step of solidifying the layer comprises evaporating the carrier liquid and then pyrolyzing the surfactant. 24. The method of claim 23, wherein the solidifying step further comprises sintering the polymer matrix. 25. The method of claim 18, wherein the step of solidifying the layer comprises evaporating the carrier liquid and then pyrolyzing the viscosity modifier. 26. The method of claim 25, wherein the solidifying step further comprises sintering the polymer matrix. 27. A polymer matrix composite film with a granular filler produced by the method of claim 1. 28. A carrier liquid, fluoropolymer matrix material, and filler material particles, said fluoropolymer matrix material and filler material comprising 15 volumes.
A casting composition for casting a particulate filled fluoropolymer matrix composite film contained in the composition in a relative amount effective to obtain a dry composite film comprising greater than or equal to% filler material. 29. The composition of claim 28, wherein the mixture comprises a co-dispersion of particles of fluoropolymer and particles of filler material in a carrier liquid. 30. The composition according to claim 28, wherein the carrier liquid comprises water. 31. The fluoropolymer is polytetrafluoroethylene, polyvinylidene fluoride, polychlorotrifluoroethylene, polyvinyl fluoride, tetrafluoroethylene / hexafluoropropylene / ethylene copolymer, chlorotrifluoroethylene / vinylidene fluoride copolymer, chloro. 29. The composition of claim 28, selected from the group consisting of trifluoroethylene / hexafluoropropylene, chlorotrifluoroethylene / ethylene copolymers and mixtures thereof. 32. The composition of claim 28, wherein the filler particles comprise coated inorganic filler particles that include an inorganic core and a coating layer surrounding the core. 33. The composition of claim 32, wherein the coating layer is selected from the group consisting of silane coating, zirconate coating and titanate coating. 34. A relative amount effective to obtain a particulate filled fluoropolymer matrix composite film consisting of an aqueous co-dispersion of fluoropolymer particles and glass or ceramic filler particles having 15% by volume or more of filler particles. Forming a casting composition comprising fluoropolymer particles and filler particles, casting a casting composition layer on a substrate, and then drying the cast layer on the substrate to form the substrate layer and the particles adhered to the substrate layer. A method of making a composite laminated electrical circuit material comprising forming a composite laminated electrical circuit material comprising a filled fluoropolymer matrix composite film. 35. The fluoropolymer is polytetrafluoroethylene, polyvinylidene fluoride, polychlorotrifluoroethylene, polyvinyl fluoride, tetrafluoroethylene / hexafluoropropylene / ethylene copolymer, chlorotrifluoroethylene / vinylidene fluoride copolymer, chloro. 35. The method of claim 34, selected from the group consisting of trifluoroethylene / hexafluoropropylene, chlorotrifluoroethylene / ethylene copolymers and mixtures thereof. 36. The method of claim 34, wherein the glass or ceramic filler particles comprise coated filler particles having a glass or ceramic core and a coating layer surrounding the core. 37. The method of claim 36, wherein the coating layer is selected from the group consisting of silane coating, zirconate coating and titanate coating. 38. The method of claim 34, wherein the filler particles have a maximum isometric sphere diameter of less than about 10 microns. 39. A particulate filled fluoropolymer matrix composite consisting of a fluoropolymer matrix and up to about 95% by volume filler particles having a maximum isometric sphere diameter of less than about 10 microns dispersed throughout the matrix. Goods. 40. The fluoropolymer is polytetrafluoroethylene; polychlorotrifluoroethylene; a copolymer of tetrafluoroethylene and a monomer selected from the group consisting of hexafluoropropylene and perfluoroalkyl vinyl ethers; tetrafluoroethylene and fluorine. A copolymer of vinylidene fluoride, a monomer selected from the group consisting of vinyl fluoride and ethylene; or chlorotrifluoroethylene and a group selected from the group consisting of hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, vinyl fluoride and ethylene. 4. A copolymer with a monomer
The film according to item 9. 41. The film of claim 39, wherein the filler particles comprise inorganic particles selected from the group consisting of glass particles, ceramic particles and mineral particles. 42. The film of claim 39, wherein the filler particles consist of synthetic polymer particles. 43. The film of claim 39, wherein the filler particles comprise coated inorganic filler particles including an inorganic core and a coating layer surrounding the core. 44. The film of claim 43, wherein the coating layer is selected from the group consisting of silane coating, zirconate coating and titanate coating. 45. The film of claim 39, wherein the article comprises a film having a thickness of less than about 2 mils. 46. The film of claim 39, wherein the article comprises a film having a thickness of less than about 1 mil. 47. A particulate comprising a fluoropolymer matrix and 15% by volume or more of filler particles dispersed throughout the matrix and having a thickness of less than about 2 mils and no macroscopic pinholes or crevices. Fluoropolymer matrix composite film with filler. 48. The fluoropolymer is polytetrafluoroethylene; polychlorotrifluoroethylene; a copolymer of tetrafluoroethylene and a monomer selected from the group consisting of hexafluoropropylene and perfluoroalkyl vinyl ethers; tetrafluoroethylene and fluorine. Copolymers with monomers selected from the group consisting of vinylidene fluoride, vinyl fluoride and ethylene; or selected from the group consisting of chlorotrifluoroethylene and hexafluoropropylene, perfluoroalkyl vinyl ethers, vinylidene fluoride, vinyl fluoride and ethylene. 48. The film of claim 47, which comprises a copolymer with a monomer as defined above. 49. The film of claim 47, wherein the filler particles comprise inorganic particles selected from the group consisting of glass particles and ceramic particles. 50. The film of claim 47, wherein the filler particles comprise coated inorganic filler particles comprising an inorganic core and a coating layer surrounding the core. 51. The film of claim 50, wherein the coating layer is selected from the group consisting of silane coating, zirconate coating and titanate coating. 52. A laminated composite electrical circuit comprising a dielectric layer comprising a fluoropolymer matrix and up to about 95% by volume filler particles dispersed throughout the matrix having a maximum isometric sphere diameter of less than about 10 microns. substrate. 53. A porous fluoropolymer film less than 2 mils thick comprising a fluoropolymer matrix having a porosity of greater than or equal to about 15% by volume. 54. The fluoropolymer is polytetrafluoroethylene; polychlorotrifluoroethylene; a copolymer of tetrafluoroethylene and a monomer selected from the group consisting of hexafluoropropylene and perfluoroalkyl vinyl ethers; tetrafluoroethylene and fluorine. A copolymer of vinylidene fluoride, a monomer selected from the group consisting of vinyl fluoride and ethylene; or chlorotrifluoroethylene and a group selected from the group consisting of hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, vinyl fluoride and ethylene. 6. A copolymer with a monomer
The film according to item 3. 55. The matrix has a porosity of about 30% by volume.
54. The film of claim 53 having about 70% by volume. 56. The film of claim 53, wherein the film has a thickness of less than about 1 mil. 57. Relative amounts of filler and fluoropolymer such that a dispersion of a particulate filler in a carrier liquid is mixed with a fluoropolymer to give a particulate filled composite film having 15% by volume or more of the filler. Producing a casting composition comprising, and casting the casting composition layer on a substrate, solidifying the layer to form a fluoropolymer matrix composite film with particulate filler, and then removing the particulate filler from the solidified layer. A method for producing a porous fluoropolymer film, the method comprising: producing a porous fluoropolymer film. 58. The method of claim 57, wherein the carrier liquid is water and the casting composition comprises an aqueous co-dispersion of fluoropolymer particles and filler particles. 59. The fluoropolymer is polytetrafluoroethylene; polychlorotrifluoroethylene; a copolymer of tetrafluoroethylene and a monomer selected from the group consisting of hexafluoropropylene and perfluoroalkyl vinyl ethers; tetrafluoroethylene and fluorine. A copolymer of vinylidene fluoride, vinyl fluoride and ethylene with a monomer selected from the group consisting of chlorotrifluoroethylene and hexafluoropropylene, perfluoroalkyl vinyl ethers, vinylidene fluoride, vinyl fluoride and ethylene. 58. Copolymer with selected monomers.
The method described in. 60. The method of claim 57, wherein the filler particles consist of polystyrene particles or polymethylmethacrylate particles. 61. The method of claim 57, wherein the filler particles have a maximum isometric sphere diameter of about 10 microns. 62. The method of claim 57, wherein the filler particles have a maximum isometric sphere diameter of less than 5 microns. 63. The method of claim 57, wherein the solidified film has a thickness of less than about 2 mils. 64. The method of claim 57, wherein the solidified film has a thickness of less than 1 mil. 65. The method of claim 57, further comprising adjusting the viscosity of the casting composition so that no particulate filler separates from the composition. 66. The method of claim 65, wherein the viscosity modifier is selected from the group consisting of polyacrylic acid, vegetable gums and cellulose based compounds. 67. The layer is a dispersion coating, roll-
58. The method of claim 57 cast by roll coating, reverse roll coating or metering and rod coating. 68. The method of claim 57, wherein the filler particles are removed from the solidified layer by thermal decomposition, chemical reaction or dissolution. 69. A porous fluoropolymer film produced by the method of claim 57.