WO2022141019A1

WO2022141019A1 - Composite particulate material, process and use thereof

Info

Publication number: WO2022141019A1
Application number: PCT/CN2020/140638
Authority: WO
Inventors: Minfang Mu; Qiuju Wu
Original assignee: Dupont Electronics, Inc.
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-07-07
Also published as: TW202246406A

Abstract

Disclosed is a composite particulate material comprising a fluoropolymer particle and an inorganic nanoparticle. Also disclosed is a process for making the composite particulate. A dielectric film comprising the fluoropolymer composite particulate and use of the composite particulate in electronic devices are also disclosed.

Description

[Title established by the ISA under Rule 37.2] COMPOSITE PARTICULATE MATERIAL, PROCESS AND USE THEREOF

FIELD OF THE DISCLOSURE

The present disclosure relates to a composite particulate material comprising a fluoropolymer particle and an inorganic nanoparticle and a process for making the composite particulate. It further relates to a dielectric film comprising the fluoropolymer composite particulate and use of the composite particulate in electronic devices.

BACKGROUND INFORMATION

Resinous particulate material as a filler in a resinous composition are widely used in the microelectronic industry. The rapid development of the microelectronics industry has created a great demand for dielectric polymeric materials used in printed circuit board (PCB) with improved electrical characteristics. With massive data transfer at a premium, computers and other electronic devices are moving to higher frequencies. Many systems now operate in the 1 to 10 GHz range, while new applications will run at frequencies as high as 20 GHz, or 30 GHz, or beyond 100 GHz.

Fluoropolymer particulates have been used as fillers in a polymeric composition for making printed circuit board due to its low dielectric constant (D _k) and dissipation factor (D _f) which are desired in high frequency signal transmission. However, fluoropolymer particles have poor adhesion to the polymeric composition due to its inert chemistry, which leads to lower mechanical properties. Surface modification on the fluoropolymer particulates are used to improve its compatibility to the polymeric composition and hence, to improve the mechanical property. In some circumstances, inorganic particulate material has been used to modify the non-sticky surface of the fluoropolymer particulates and form composite particulates. However, the fluoropolymer particulates or the inorganic particulates have to be coated with a primer or adhesion promoter having compatibility with both fluoropolymer and inorganic particulates.

Fluoropolymer composite particulates are desired to be free from substances with a high environmental impact. A need is existed for making fluoropolymer composite particulates without using any primer or adhesion promoter while an inorganic particulate material is uniformly and solidly attached to a fluoropolymer particulate material.

The present disclosure provides a fluoropolymer composite particulate which is substantially free of primer or adhesion promoter including silane and hydroxyl functional groups. The fluoropolymer composite particulate can be used as a filler in a polymeric composition to form a film that is uniformly adhered to a substrate and has excellent adhesion to the substrate while maintaining low dielectric and good mechanical properties.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated in the accompanying figures to improve understanding of concepts as presented herein.

FIG. 1 is a photograph showing the results of an observation with an optical microscope on the Film 2/Cu foil laminate drilled with a 355 nm UV laser according to the present disclosure.

FIG. 2 is a photograph showing the results of an observation with an optical microscope on the Film 3/Cu foil laminate drilled with a 355 nm UV laser according to the present disclosure.

FIG. 3 is a photograph showing the results of an observation with an optical microscope on the Film 5/Cu foil laminate drilled with a 355 nm UV laser according to the present disclosure.

FIG. 4 is a scanning-electron-microscope (SEM) photograph (magnification x 2000) showing the results of observing the cross section of Film 11 according to the present disclosure.

FIG. 5 is a SEM photograph (magnification x 2000) showing the results of observing the cross section of Film 13 according to the present disclosure.

DETAILED DESCRIPTION

As used throughout this specification, the following abbreviations shall have the following meanings, unless the context clearly indicates otherwise: ℃ = degree Celsius; g =gram; nm = nanometer; μm = micron = micrometer; mm = millimeter; sec. = second; min. =minute; hr = hour; rpm = revolutions per minute; and kgf/cm ² = kilogram-force per square centimeter. All amounts are percent by weight ( "wt. %" ) and all ratios are molar ratios, unless otherwise noted. All numerical ranges are inclusive and combinable in any order, except where it is clear that such numerical ranges are constrained to added up to 100%. Unless otherwise noted, all polymer and oligomer molecular weights are weight average molecular weights ( 'Mw" ) with unit of g/mol or Dalton, and are determined using gel permeation chromatography compared to polystyrene standards.

The term "substantially free" means that 5%or less, or 4%or less, or 3%or less, or 2%or less, or 1%or less of silane or hydroxyl functional groups is present in a composite particulate material.

The terms "film" , "sheet" and "layer" are used interchangeably through this specification.

The terms "powder (s) " , "particulates" and "particles" are used interchangeably through this specification.

In this specification, unless explicitly stated otherwise or indicated to the contrary by the context of usage, where an embodiment of the subject matter hereof is stated or described as comprising, including, containing, having, being composed of or being constituted by or of certain features or elements, one or more features or elements in addition to those explicitly stated or described may be present in the embodiment. An alternative embodiment of the disclosed subject matter hereof, is described as consisting essentially of certain features or elements, in which embodiment features or elements that would materially alter the principle of operation or the distinguishing characteristics of the embodiment are not present therein. A further alternative embodiment of the described subject matter hereof is described as consisting of certain features or elements, in which embodiment, or in insubstantial variations thereof, only the features or elements specifically stated or described are present.

Also, use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

To the extent not described herein, many details regarding specific materials, processing acts, and circuits are conventional and may be found in textbooks and other sources within the organic light-emitting diode display, photodetector, photovoltaic cell, and semiconductive member arts.

The present disclosure provides a composite particulate material comprising a fluoropolymer particle, and an inorganic nanoparticle having an average particle size of less than 200 nm, wherein the composite particulate is substantially free of silane or hydroxyl functional groups. In some embodiments, the composite particulate material comprises 5%or less, or 4%or less, or 3%or less, or 2%or less, or 1%or less of silane or hydroxyl functional groups. In one embodiment, a composite particulate material comprises a fluoropolymer particle as a core cladded with inorganic nanoparticles.

For purposes of the present disclosure, the term fluoropolymer is intended to mean any polymer having at least one, if not more, fluorine atoms contained within the repeating unit of the polymer structure. The term fluoropolymer, or fluoropolymer component, is also intended to mean a fluoropolymer resin (i.e. a fluoro-resin) . These terms are used interchangeably through this specification.

Commonly, fluoropolymers are polymeric material containing fluorine atoms covalently bonded to, or with, the repeating molecule of the polymer. Suitable fluoropolymer components of the present disclosure can include:

1. “PFA” is a poly (tetrafluoroethylene-co-perfluoro [alkyl vinyl ether] ) , including variations or derivatives thereof, having the following moiety representing at least 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99 or about 100 weight percent of the entire polymer:

where R ₁ is C _nF _2n+1, where n can be any natural number equal to or greater than 1 including up to 20 or more, typically n is equal to 1 to three; x and y are mole fractions, where x is in a range from 0.95 to 0.99, typically 0.97; and y is in a range from 0.01 to 0.05, typically 0.03, and where the melt flow rate, described in ASTM D 1238, is in a range of from 1 to 100 (g/10 min. ) , or 1 to 50 (g/10 min. ) , or 2 to 30 (g/10 min. ) , or 5 to 25 (g/10 min. ) .

2. “FEP” is a poly (tetrafluoroethylene-co-hexafluoropropylene) [a.k.a. poly (tetrafluoroethylene-co-hexafluoropropylene) copolymer] , derived in whole or in part from tetrafluoroethylene and hexafluoropropylene, including variations or derivatives thereof, having the following moiety representing at least 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99 or about 100 weight percent of the entire polymer:

where x and y are mole fractions, where x is in a range from 0.85 to 0.95, or 0.92; y is in a range from 0.05 to 0.15, or 0.08; and where the melt flow rate, described in ASTM D 1238, is in a range of from 1 to 100 (g/10 min. ) , or 1 to 50 (g/10 min. ) , or 2 to 30 (g/10 min. ) , or 5 to 25 (g/10 min. ) . The FEP copolymer used in the present disclosure can be derived directly or indirectly from: (i. ) 50, 55, 60, 65, 70 or 75 percent to about 75, 80, 85, 90 or 95 percent tetrafluoroethylene; and (ii. ) 5, 10, 15, 20, or 25 percent to about 25, 30, 35, 40, 45 or 50 percent (generally 7 to 27 percent) hexafluoropropylene.

3. “PTFE” is a polytetrafluoroethylene, including variations or derivatives thereof, derived in whole or in part from tetrafluoroethylene and having the following moiety representing at least 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99 or about 100 weight percent of the entire polymer:

-(CF ₂-CF ₂) _x-

where x is equal to any natural number between 50 and 500,000.

4. “ETFE” is a poly (ethylene-co-tetrafluoroethylene) , including variations or derivatives thereof, derived in whole or in part from ethylene and tetrafluoroethylene and having the following moiety representing at least 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99, or about 100 weight percent of the entire polymer:

- (CH ₂-CH ₂) _x- (CF ₂-CF ₂) _y-

where x and y are mole fractions, where x is in a range from 0.40 to 0.60, or 0.50; and y is in a range from 0.40 to 0.60, or 0.50; and where the melt flow rate, described in ASTM D 1238, is in a range of from 1 to 100 (g/10 min. ) , or 1 to 50 (g/10 min. ) , or 2 to 30 (g/10 min. ) , or 5 to 25 (g/10 min. ) .

Fluoropolymer resins are generally known for their high-temperature stability, resistance to chemical attack, advantageous electrical properties (high-frequency properties in particular) , low moisture absorption, low friction properties, and low tackiness. Other potentially useful fluoropolymers can include, but are not limited to, chlorotrifluoroethylene polymer (CTFE) , tetrafluoroethylene chlorotrifluoroethylene copolymer (TFE/CTFE) , tetrafluoroethylene-perfluoro dioxyolane copolymer (TFE/PDD) , polychlorotrifluoroethylene (PCTFE) , ethylene chlorotrifluoroethylene copolymer (ECTFE) , polyvinylfluoride (PVF) and polyvinylidene fluoride (PVDF) . Two or more of these fluoropolymers can be used in the present disclosure.

Fluoropolymer resins can be converted to micro powders or particles by milling the resins in a hammer mill, or by using other mechanical means for reducing particle size. In one embodiment, the resin is cooled, such as with solidified carbon dioxide or liquid nitrogen, prior to grinding or other mechanical manipulation to decrease particle size. The fluoropolymer micro powders or particles of the present disclosure may possess either a high molecular weight species and/or a low molecular weight species. The average particle size of the fluoropolymer can be varied from 0.05 to 100 μm, or from 0.5 to 50 μm, or from 0.5 to 20 μm, or from 1 to 20 μm, or from 1 to 18 μm, or from 1 to 15 μm. Commercial products of fluoropolymer particles can include, but are not limited to, MJX-10000 (perfluoroalkoxy alkane powder with an average particle size of 4.5 μm, commercially available from Chemours -Mitsui Fluoroproducts Co., Ltd., Tokyo, Japan) ; 532G-9420 PFA POWDER CLEAR (perfluoroalkoxy alkane powder with an average particle size of 7 μm, commercially available from The Chemours Company FC, LLC, Wilmington, Delaware) ; 3M ^TM Dyneon ^TM Fluoroplastic Powder FEP 6322PZ (fluorinated ethylene propylene powder with an average particle size of 6.4 μm, commercially available from The 3M Company, Saint Paul, Minnesota) ;

F5 A (polytetrafluoroethylene powder with an average particle size of 4 μm, commercially available from Solvay S.A., Brussels, Belgium) ; INOFLON PFA 8115 (perfluoroalkoxy alkane powder with an average particle size of 20 μm, commercially available from GFL America, LLC, Rockdale, Texas) ; FEP Micropowder TPD-700S (fluorinated ethylene propylene powder with an average particle size of 4-20 μm, commercially available from Fuzhou Topda New Material Co., Ltd., Fuzhou, China) ; and FLUO 300 (polytetrafluoroethylene powder with an average particle size of 5-6 μm, commercially available from Micro Powders, Inc. Tarrytown, NY) .

In some embodiments, the inorganic nanoparticles are substantially uniformly distributed on a surface of the fluoropolymer particle. The inorganic nanoparticles comprise at least one kind of inorganic oxide nanoparticles including, but not limited to, cesium oxide (ceria) , silicon oxide (such as silica) , zirconium oxide (such as zirconia) , aluminum oxide (such as alumina) , titanium oxide (such as titania) and iron oxide. In some embodiments, two or more of the above inorganic nanoparticles can be used. A ratio of the average particle size of the inorganic nanoparticle to the average particle size of the fluoropolymer particle can be varied from 1/50 to 1/10,000, or from 1/20 to 1/2000, or from 1/10 to 1/5000. The average particle size of the inorganic nanoparticle can be ranged from 1 to 195 nm, or from 3 to 185 nm, or from 5 to 175 nm, or from 5 to 150 nm, or from 5 to 100 nm, or from 5 to 80 nm, or from 5 to 70 nm.

Further, the inorganic nanoparticles may be composite inorganic nanoparticles in which two or more kinds of inorganic nanoparticles as described above are compounded. In one embodiment, the inorganic nanoparticles comprise composite inorganic nanoparticles containing zirconia and ceria nanoparticles wherein ceria nanoparticles are adhered or bonded to the surface of the zirconia nanoparticles. In another embodiment, the inorganic nanoparticles comprise composite inorganic nanoparticles containing titanium oxide nanoparticles with a layer of silicon oxide on the surface. The inorganic nanoparticles can be in an amount of 0.1 to 10 wt%based on the total weight of the composite particulate material. In some embodiments, the inorganic nanoparticles can be in an amount of 0.5 to 10 wt%, or 1 to 10 wt%, or 1.5 to 7 wt%based on the total weight of the composite particulate material.

The present disclosure is also directed to a process of making a composite particulate material comprising steps of: (a) providing a fluoropolymer particle and an inorganic nanoparticle with an average particle size of less than 200 nm; and (b) mechanically mixing the fluoropolymer particle and the inorganic nanoparticle at a rotation speed of 500 to 10,000 rpm for less than 30 minutes at temperature of less than 200 ℃. In some embodiments, the fluoropolymer particle and the inorganic nanoparticle can be mixed at a rotation speed of from 1,000 to 9,000 rpm, or from 3,000 to 8,000 rpm. The fluoropolymer particle and the inorganic nanoparticle can be mixed at a temperature less than 150 ℃, or less than 100 ℃, or less than 70 ℃. Any suitable high performance powder processing machine for nanoparticles can be used for the mixing. The rotation speed and time can be changed depending on the rotor size and the processing machine. The inorganic nanoparticles are dispersed without agglomeration after the mixing. No binder is needed in the present disclosure for the mixing. Examples of such mixer can include, but are not limited to Nobilta ^TM NOB Mini (commercially available from Hosokawa Micron Corporation, Osaka, Japan) , and Nara Hybridization System (commercially available from Nara Machinery Co., LTD, Tokyo, Japan) .

The present disclosure is further directed to a dielectric film comprising a polymer or resin and the composite particulate material of the present disclosure. The polymer or resin can be selected from the group consisting of polyimide (PI) , polyamide imide, polystyrene-block-poly (ethylene-ran-butylene) -block-polystyrene-graft-maleic anhydride (SEBS) , epoxy resin, hydrocarbon resin, polyester resin, urea resin, silicone resin, polyphenylene ether resin, modified polyphenylene ether resin, liquid-crystal polymer resin, and combinations thereof.

In one aspect, the dielectric film of the present disclosure can be made from a liquid composition comprising the polymer and the composite particulate material dissolving and/or dispersing in one or more organic solvents. In one embodiment, the liquid composition comprises the composite particulate material, SEBS and an organic solvent such as toluene. In another embodiment, the liquid composition comprises the composite particulate material, polyimide and an organic solvent.

In another aspect, the dielectric film of the present disclosure can be made from polymerizing and curing a liquid solution that comprises monomer (s) and/or prepolymer and/or polymer precursors; the composite particulate material; and one or more organic solvents. The composite particulate material is the same as those described previously.

In one embodiment, the liquid solution can comprise a dianhydride, a diamine, the composite particulate material, and one or more organic solvents. In another embodiment, the liquid solution can comprise a polyamic acid, the composite particulate material, and one or more organic solvents. "Dianhydride" as used herein is intended to include precursors or derivatives thereof, which may not technically be a dianhydride but would nevertheless react with a diamine to form a polyamic acid which could in turn be converted to a polyimide. "Diamine" as used herein is intended to include precursors or derivatives thereof, which may not technically be a diamine but would nevertheless react with a dianhydride to form a polyamic acid which could in turn be converted into a polyimide. "Polyamic acid" as used herein is intended to include any polyimide precursor material derived from a combination of dianhydride and diamine monomers or functional equivalents thereof and capable of conversion to a polyimide via a thermal or chemical conversion process.

The dianhydride can be selected from the group consisting of pyromellitic dianhydride (PMDA) ; 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA) ; 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride; , 3, 3', 4, 4'-diphenylsulfonetetracarboxylic dianhydride; 4, 4'- (hexafluoroisopropylidene) diphthalic anhydride (6FDA) ; cyclobutane-1, 2, 3, 4-tetracarboxylic dianhydride (CBDA) ; cyclopentanetetracarboxylic dianhydride (CPDA) ; and combinations thereof. Optionally, the dianhydride can further include alicyclic dianhydride selected from the group consisting of cyclobutene dianhydride; cyclohexane dianhydride; 1, 2, 3, 4-cyclopentanetetrcarboxylic dianhydride; hexahydro-4, 8-ethano-1H, 3H-benzo [1, 2-c: 4, 5-c'] difuran-1, 3, 5, 7-tetrone; 3- (carboxymethyl) -1, 2, 4-cyclopentanetricarboxylic acid 1, 4, 2, 3-dianhydride; meso-butane-1, 2, 3, 4-tetracarboxylic acid dianhydride; 1, 2, 3, 4, 5-cyclohexanetetracarboxylic dianhydride; and combination thereof.

The diamine can be selected from the group consisting of 3, 4'-oxydianiline; 4, 4'-oxydianiline (ODA) ; 1, 4-diaminobenzene; 1, 3-diaminobenzene; and 4, 4'-diaminophenyl. The diamine can be a fluorinated aromatic diamine such as 2, 2'-bis (trifluoromethyl) -1, 1'-biphenyl-4, 4'-diamine (TFDB) . Optionally, the diamine can further include aliphatic and/or alicyclic diamine . The aliphatic diamine can be selected from the group consisting of 1, 2-diaminoethane; 1, 4-diaminobutane; 1, 5-diaminopentane; 1, 6-diaminohexane; 1, 7-diaminoheptane; 1, 8-diaminooctane; 1, 9-diaminononane; 1, 10-diaminodecane; 1, 11-diaminoundecane; 1, 12-diamniododecane; 1, 16-hexadecamethylenediamine; 1, 3-bis (3-aminopropyl) -tetramethyldisiloxane; isophoronediamine; bicyclo [2.2.2] octane-1, 4-diamine and combinations thereof. The alicyclic diamine can be selected from the group consisting of cis-1, 3-diaminocyclobutane trans-1, 3-diamniocyclobutane; 6-amino-3-azaspiro [3.3] heptane; 3, 6-diaminospiro [3.3] hetane; bicyclo [2.2.1] octane-1, 4-diamine; 1, 4-cyclohexane methylenebis (cyclohexylamine) ; 4, 4'-methylenebis (2-methyl-cyclohexylamine) ; bis (amniomethyl) norbornane and combinations thereof.

In some embodiments, the dielectric film can be made from a liquid composition comprising the composite particulate material, polyamide-imide, and one or more organic solvents. The polyamide-imide comprises a copolymer derived from an aromatic dianhydride, an aromatic diamine and an aromatic dicarbonyl compound. The aromatic dianhydride can be selected from the group consisting of 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA) , 4, 4'- (hexafluoroisopropylidene) diphthalic anhydride (6FDA) , cyclobutane-1, 2, 3, 4-tetracarboxylic dianhydride (CBDA) , cyclopentanetetracarboxylic dianhydride (CPDA) , and combinations thereof. The aromatic diamine can be a fluorinated aromatic diamine such as 2, 2'-bis (trifluoromethyl) -1, 1'-biphenyl-4, 4'-diamine (TFDB) . The aromatic dicarbonyl compound can be selected from the group consisting of p-terephthaloyl chloride (TPC) , terephthalic acid, iso-phthaloyl dichloride, and 4, 4'benzoyl chloride. The polyamide-imide film and preparation are disclosed in U.S. Patent Nos. 9,018,343 and 9,580,555, the entire contents of which are incorporated herein by reference.

Suitable organic solvents are those in which the polymers are soluble and/or dispersed. Exemplary organic solvents include, without limitation, polar protic and polar aprotic solvents, for example, benzene, toluene, xylene, alcohols such as 2-methyl-1-butanol, 4-methyl-2-pentanol, and methyl isobutyl carbinol; esters such as ethyl lactate, propylene glycol methyl ether acetate, dimethylacetamide, methyl 2-hydroxyisobutyrate, methyl 3-methoxypropionate, n-butyl acetate and 3-methoxy-1-butyl acetate; lactones such as gamma-butyrolactone; lactams such as N-methyl pyrrolidinone; ethers such as propylene glycol methyl ether and dipropylene glycol dimethyl ether isomers, such as PROGLYDE ^TM DMM (The Dow Chemical Company, Midland, MI) ; ketones such as 2-butanone, cyclopentanone, cyclohexanone and methylcyclohexanone; and mixtures thereof.

Suitable additives can be optionally added into the liquid compositions or liquid solutions. Examples of the additives can include, without limitation, one or more of each of curing agents, crosslinkers, surfactants, inorganic fillers, organic fillers, plasticizers, metal passivating materials, inhibitors, flame retardants and combinations of any of the foregoing. Suitable surfactants are well-known to those skilled in the art, and nonionic surfactants are preferred. Such surfactants may be present in an amount of from 0 to 10 g/L, or from 0 to 5 g/L.

Any suitable inorganic fillers may optionally be used in the present compositions, and are well-known to those skilled in the art. Exemplary inorganic fillers can include, but are not limited to, silica, silicon carbide, silicon nitride, alumina, aluminum carbide, aluminum nitride, zirconia, and mixtures thereof. The inorganic filler may be in the form of powders, rods, spheres, or any other suitable shapes. Such inorganic fillers may have any suitable dimensions. Inorganic fillers may be used in an amount of from 0 to 80 wt. %, or from 40 to 80 wt. %, as solids based on the total weight of the composition. In some embodiments, no inorganic fillers are present.

The metal passivating material can be a copper passivating agent. Suitable copper passivating agents are well known in the art and include imidazoles, benzotriazoles, ethylene diamine or its salts or acid esters, and iminodiacetic acids or salts thereof.

The liquid compositions or liquid solutions as described above can be coated or deposited on a surface of a substrate to form a film using any known technique and heated to remove solvent. In one embodiment, the liquid composition can be soft baked at a suitable temperature, such as from 90 to 140 ℃, for an appropriate time, such as from 1 to 30 minutes, to remove any solvent. This can be followed by an additional heating step to cure the film. Suitable methods for coating or disposing the liquid compositions of the present disclosure on the surface of the substrate can include, but are not limited to, spin-coating, curtain coating, spray coating, roller coating, dip coating, vapor deposition, slot-die coating, gravure printing, and lamination such as vacuum lamination, among other methods.

Any substrate known in the art can be used in the present disclosure. Examples of the substrate can include, but are not limited to, silicon, copper, silver, indium tin oxide, silicon dioxide, glass, silico nitride, aluminum, gold, polyimide and epoxy mold compound, be a polyester sheet such as polyethylene terephthalate (PET) sheet, a polyimide sheet such as KAPTON ^TM polyimide (DuPont, Wilmington, DE) ., or their combinations thereof. The film formed on the substrate can be used directly or can be peeled off as a free-standing film and used on different substrates in electronic devices. The free-standing film can be laminated onto the substrate surface using roll-lamination or vacuum lamination with or without using an adhesive layer. The lamination temperature can range from 100 to 400 ℃, or from 140 to 400 ℃, or from 140 to 300℃.

The dielectric film of the present disclosure has good tensile strength, tensile elongation, good adhesion to desired substrates such as copper, and low dielectric loss at high frequency. The dielectric films can have D _k values less than 3.0, or less than 2.5, or less than 2.2; and D _f values less than 0.004, or less than 0.003, or less than 0.0025 at high frequencies such as 10 GHz, or 20 GHz, or 30 GHz.

The present disclosure is also directed to a wide variety of electronic devices comprising at least one layer of the dielectric film of the present disclosure on an electronic device substrate. The electronic device substrate can be any substrate for use in the manufacture of any electronic device. Exemplary electronic device substrates include, without limitation, semiconductor wafers, glass, sapphire, silicate materials, silicon nitride materials, silicon carbide materials, display device substrates, epoxy mold compound wafers, circuit board substrates, and thermally stable polymers. As used herein, the term "semiconductor wafer" is intended to encompass a semiconductor substrate, a semiconductor device, and various packages for various levels of interconnection, including a single-chip wafer, multiple-chip wafer, packages for various levels, substrates for light emitting diodes (LEDs) , or other assemblies requiring solder connections. Semiconductor wafers, such as silicon wafers, gallium-arsenide wafers, and silicon-germanium wafers, may be patterned or unpatterned. As used herein, the term "semiconductor substrate" includes any substrate having one or more semiconductor layers or structures which include active or operable portions of semiconductor devices. The term "semiconductor substrate" is defined to mean any construction comprising semiconductive material, such as a semiconductor device. A semiconductor device refers to a semiconductor substrate upon which at least one microelectronic device has been or is being fabricated. Thermally stable polymers include, without limitation, any polymer stable to the temperatures used to cure the arylcyclobutene material, such as polyimide, for example, KAPTON ^TM polyimide (DuPont, Wilmington, DE) , liquid crystalline polymers, for example VECSTAR ^TM LCP film (Kuraray, Tokyo, Japan) and Bismaleimide-Triazine (BT) resins (MGC, Tokyo, Japan) .

EXAMPLES

The concepts described herein will be further described in the following examples, which do not limit the scope of the disclosure described in the claims. Unless otherwise indicated, all units of temperature are room temperature (20-25 ℃) and all units of pressure are standard pressure or 101 kPa.

Materials

(1) Filler

PFA-1: Perfluoroalkoxy alkane powder (MJX-10000, average particle size of 4.5 μm, commercially available from Chemours -Mitsui Fluoroproducts Co., Ltd., Tokyo, Japan)

PFA-2: Perfluoroalkoxy alkane powder (532G-9420 PFA POWDER CLEAR, average particle size of 7 μm, commercially available from The Chemours Company FC, LLC, Wilmington, Delaware)

FEP: Fluorinated ethylene propylene powder (3M ^TM Dyneon ^TM Fluoroplastic Powder FEP 6322PZ, average particle size of 6.4 μm, commercially available from The 3M Company, Saint Paul, Minnesota)

Al ₂O ₃: Alumina (

Alu 65, primary particle size 20 nm, commercially available from Evonik Industries AG, Essen, Germany)

TiO ₂: Titanium Dioxide (

TiO ₂ P 25, primary particle size 30 nm, commercially available from Evonik Industries AG, Essen, Germany)

(2) Organics:

SEBS: Polystyrene-block-poly (ethylene-ran-butylene) -block-polystyrene-graft-maleic anhydride with melt index ～21 g/10 min (230℃/5.0kg) ;

ODA: 4, 4′-Oxydianiline;

PMDA: Pyromellitic dianhydride;

NMP: N-Methyl-2-pyrrolidone;

All of the organics were purchased from Sigma Aldrich.

(3) Substrates:

Cu foil: CF-TGFB-THE with an average thickness of 18 μm, commercially available from

Suzhou Fukuda Metal Co., LTD, Suzhou, China.

PI film:

EN with an average thickness of 50 μm, commercially available from DuPont-Toray Co., LTD, Tokyo, Japan.

Processing Fluoropolymer Powders

PFA-1, PFA-2 and FEP were further processed in a Nobilta ^TM NOB Mini (commercially available from Hosokawa Micron Corporation, Osaka, Japan) at a rotation speed of 7,000 rpm for 9 minutes. The process was controlled under temperature below 70℃ with cooling water. The processed fluoropolymer powders were named as m-PFA-1, m-PFA-2 and m-FEP, respectively.

Film Preparation

Film 1 - 4 g of SEBS was dissolved in 10 g of toluene with stirring overnight to form a SEBS/toluene solution. The SEBS/toluene solution was cast through an automatic casting machine on a glass substrate and then dried in an oven at 130℃ for 5 min to form Film 1. The formed Film 1 was peeled from the glass substrate as a free-standing film with a thickness of 25 μm.

Film 2 -4 g of SEBS was dissolved in 10 g of toluene with stirring overnight to form a solution. 6 g of PFA-1 was added into and mixed with the solution, The mixing was carried out using a Planetary Centrifugal Mixer "THINKY MIXER" ARE-310 (commercially available from Thinky USA Inc., Laguna Hills, California) at 2000 rpm for 1 min ( "Thinky Process" ) . The Thinky Process was repeated for 3 times. After that, the mixture was degassed at 2400 rpm for 1min to form a PFA-1/SEBS/toluene mixture. The PFA-1/SEBS/toluene mixture was cast through an automatic casting machine on a glass substrate and then dried in an oven at 130℃ for 5 min to form Film 2. The formed Film 2 was peeled from the glass substrate as a free-standing film with a thickness of 25 μm.

Film 3 -Film 3 was prepared using the same procedure as Film 2 except that PFA-1 was replaced with m-PFA-1.

Film 4 -28 g of m-PFA-1 and 0.57g of Al ₂O ₃ were added into the Nobilta NOB Mini. The machine was run at a rotation speed of 3000 rpm for 1 minute and then the rotation speed was increased to 7000 rpm and maintained for 9 mins. The process was carried out under temperature below 70℃ with cooling water to form fluoropolymer powders coated with Al ₂O ₃. Finally, the coated powders were collected as fluoropolymer composite particulates after opening all the air valves. Film 4 was prepared using the same procedure as Film 2 except that the PFA-1 was replaced with the fluoropolymer composite particulates prepared as above.

Films 5 & 6 -Films 5 and 6 were prepared using the same procedure as Film 4 except that 1.14 g Al ₂O ₃ were used in the fluoropolymer composite particulates for Film 5 and 1.71 g of Al ₂O ₃ were in the fluoropolymer composite particulates for Film 6.

Films 7 & 8 -Films 7 and 8 were prepared using the same procedure as Film 2 and Film 3 except that PFA-1 and m-PFA-1 were replaced with FEP and m-FEP, respectively.

Film 9 -Film 9 was prepared using the same procedure as Film 4 except that m-PFA-1 was replaced with m-FEP; and 0.57 g of Al ₂O ₃ was replaced with 0.51 g of TiO ₂ and 0.37 g of Al ₂O ₃.

Film 10 -31 g of ODA was dissolved in 214 g of NMP at 30℃ with stirring under N ₂. Then, 33 g of PMDA was gradually added to form a PMDA-ODA solution. The solution was kept overnight under continuous N ₂ flow. The solution was cast through an automatic casting machine on a glass substrate and then dried in an oven in air at 110℃ for 30 min. The dried glass substrate with coating was held in a glove box under N ₂ at 350℃ for 1 hr. to form a polyimide film. The formed polyimide film was then peeled from the glass substrate as a free-standing film with a thickness of 25 μm.

Film 11 -The PMDA-ODA solution was prepared using the same procedure as described in Film 10.60 wt%of PFA-2 was added into and mixed with the PMDA-ODA solution based on the total amounts of PFA-2 and PMDA-ODA. The mixing was carried out using a Planetary Centrifugal Mixer "THINKY MIXER" ARE-310 at 2000 rpm for 1 min ( "Thinky Process" ) . The Thinky Process was repeated for 3 times. After that, the mixture was degassed at 2400 rpm for 1min. The mixture was then cast through an automatic casting machine on a glass substrate and then dried in an oven at 110℃ for 30 min in air. The dried glass substrate with coating was held in glove box under N ₂ flow at 350℃ for 1 hr. to form a polyimide film containing PFA-2. The formed polyimide film containing PFA-2 was then peeled off from the glass substrate as a free-standing film at a thickness of 25 μm.

Film 12 -Film 12 was prepared using the same procedure as Film 11 except that PFA-2 was replaced with m-PFA-2.

Film 13 -Film 13 was prepared using the same procedure as Film 11 except that PFA-2 was replaced with fluoropolymer composite particulates made as follows: 28 g of m-PFA-2 was added into the Nobilta NOB Mini and then N ₂ gas were filled into the chamber to purge the air out. The machine was run at 7000 rpm. After 9 minutes, 0.86 g of TiO ₂ was then added to the chamber and N ₂ was filled in to purge the air out. The machine was run at a rotation speed of 3000 rpm for 1 min and then the rotation speed was increased to 7000 rpm and maintained for 9 mins. After 9 minutes, 0.57 g of TiO ₂ was then added to the chamber and N ₂ was filled to purge the air out. The machine was run at 3000 rpm for 1 min and then the rate was increased to 7000 rpm and maintained for another 9 mins. The whole process was controlled under temperature below 70℃ with cooling water. Finally, the coated powders were collected as fluoropolymer composite particulates after opening all the air valves.

Measurement and Testing

1. Adhesion (ADH) Test

The film prepared as describe above was sandwiched between a Cu foil and a PI film. This sandwich structure was then laminated on a vacuum lamination machine under vacuum with a pressure of 19 kgf/cm ² at 180 ℃ for 5 min. The laminate was then cut into 1-cm wide strips. The adhesion was tested on a 01/LFLS/LXA/CN Lloyd material tester. 90° peeling was conducted at a speed of 2 inch/min.

2. Electrical Test

Dielectric constant (D _k) and dissipation factor (D _f) of the film were measured on N5224B-20 VPN network analyzer through cavity method at 20 GHz. The prepared films were thermally dried at 120℃ for 4 hours before the measurement.

3. Viscosity Measurement:

Viscosity of the PMDA-ODA solution was measured with a Brookfield DV3T rheometer with CP-52 spindle at shear rate of 2/s and speed of 1rpm.

4. Moisture Absorption Measurement:

Moisture absorption (wt%) of a film was measured on a TGA Q5000SA analyzer. The film was dried at 60℃ and 0%room humidity. The film was then stabilized and measured at 25℃ and 50%room humidity.

5. Elongation at Break Measurement:

The polyimide film was cut into 1 cm wide strip. The measurements were conducted on Instron 5566Q8442 with an effective testing length of 2 inches at a speed of 0.2 inch/min.

Results

Table 1 lists the compositions and testing results of the SEBS films prepared as described above.

Table 1. Compositions and Properties of Composite Particulates in SEBS Films

Table 1 shows that the addition of fluoropolymer particulates or fluoropolymer composite particulates into SEBS film maintains the film's low dielectric constant (D _k) and low dissipation factor (D _f) . The SEBS films containing the fluoropolymer particulates have lower adhesions to Cu foil and PI film compared to the SEBS film without fillers due to poor compatibility of fluoropolymer to SEBS. However, Table 1 indicates the films containing the fluoropolymer composite particulates have higher adhesion strength than the film containing the fluoropolymer particulates. For the fluoropolymer composite particulates containing only Al ₂O ₃, the adhesion strength of the film increases as more Al ₂O ₃ is added. However, the addition of small quantity of TiO ₂ increases the adhesion strength dramatically. The film adhesion strength with the fluoropolymer composite particulates closes to the film without any fillers.

The fluoropolymer composite particulates showed an improved UV drillability in SEBS film comparing to fluoropolymer particulates as shown in Figs. 1-3. A bilayer film comprising SEBS film and a Cu foil was tested. The bilayer film was laminated on a vacuum lamination machine at 180℃ under a pressure of 19 kgf/cm ² for 5 min to form a SEBS/Cu laminate. A 100 μm wide line was drilled from the SEBS film side of the SEBS/Cu laminate using 355 nm UV laser. Fig. 1 shows Film 2 side of a drilled Film 2/Cu laminate. The line as pointed by the arrow in Fig. 1 shows no Cu, which indicates that the fluoropolymer particulate filled SEBS is not removed by the UV laser and the Film 2 residual covers the Cu foil fully. Fig. 2 shows Film 3 side of a drilled Film 3/Cu laminate. Like in Fig. 1, no Cu was observed suggesting a poor UV laser drillability. Fig. 3 shows Film 5 side of a drilled Film 5/Cu laminate. A large area of Cu foil can be seen from Fig. 3 after UV laser drilling. Thus, Film 5 comprising the fluoropolymer composite particulates has dramatically improved the material UV drillability compared to the films comprising the fluoropolymer particulates _.

Table 2 shows the compositions and testing results of the polyimide films prepared as described above.

Table 2. Compositions and Properties of Composite Particulates in Polyimide Films

*Viscosity of PMDA-ODA solutions for preparing polyimide films with or without fluoropolymer and fluoropolymer composite particulates.

Table 2 shows that both D _k and D _f are decreased dramatically with the addition of fluoropolymer and fluoropolymer composite particulates as fillers into the polyimide film. The elongation at break is reduced compared to the polyimide film without fillers and with the greater reduction for m-PFA-2. However, the film containing the fluoropolymer composite particulates has higher break point compared to the film containing m-PFA-2 and close to the break point of the polyimide film without any fillers. Table 2 also indicates that the addition of the fluoropolymer particulates and fluoropolymer composite particulates has greatly reduced the moisture absorption. Also, the viscosity of the polymer solution containing fluoropolymer composite particulates is much less compared to those containing fluoropolymer particulates (PFA-2 and m-PFA-2) . Fig. 4 shows cracks at the interface between the fluoropolymer particulates and polyimide on Film 11. As shown in Fig. 5, no cracks are observed at the interface between the fluoropolymer composite particulates and polyimide on Film 13. Thus, the inorganic nanoparticles of the fluoropolymer composite particulates improve the compatability between fluoropolymer and polyimide.

Claims

A composite particulate material comprising:

a fluoropolymer particle; and

an inorganic nanoparticle having an average particle size of less than 200 nm, wherein the composite particulate material is substantially free of silane or hydroxyl functional groups.
The composite particulate material of claim 1, wherein the fluoropolymer particle is a core cladded with the inorganic nanoparticles.
The composite particulate material of claim 1 or 2, wherein the fluoropolymer particle has an average particle size of from 1 to 20 μm.
The composite particulate material of any one of claims 1 to 3, wherein the average particle size of the inorganic nanoparticle is ranged from 5 to 175 nm.
The composite particulate material of any one of claims 1 to 4, wherein the fluoropolymer particle comprises a fluoropolymer selected from the group consisting of tetrafluoroethylene perfluoroalkylvinylether copolymer (PFA) , chlorotrifluoroethylene polymer (CTFE) , tetrafluoroethylene chlorotrifluoroethylene copolymer (TFE/CTFE) , ethylene chlorotrifluoroethylene copolymer (ECTFE) , polyvinylidene fluoride (PVDF) , poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) , polytetrafluoroethylene (PTFE) , and poly (ethylene-co-tetrafluoroethylene) (ETFE) .
The composite particulate material of any one of claims 1 to 5, wherein the inorganic nanoparticle comprises an inorganic compound selected from the group consisting of alumina, silica, zirconia, titanium dioxide, and combinations thereof.
The composite particulate material of any one of claims 1 to 6, wherein a ratio of the average particle size of the fluoropolymer particle to the average particle size of the inorganic nanoparticle is at least 20.
A process of making a composite particulate material comprising steps of:

(a) providing a fluoropolymer particle and an inorganic nanoparticle with an average particle size of less than 200 nm; and

(b) mechanically mixing the fluoropolymer particle and the inorganic nanoparticle at a speed of 100 to 10,000 rpm for less than 30 minutes and at temperature of less than 200 ℃.
The process of claim 8, wherein the fluoropolymer particle and the inorganic nanoparticle are mixed at a temperature less than 150 ℃.
A dielectric film comprising a polymer and the composite particulate material of any one of claims 1 to 7.
The dielectric film of claim 10, wherein the polymer is selected from the group consisting of polyimide (PI) , polystyrene-block-poly (ethylene-ran-butylene) -block-polystyrene-graft-maleic anhydride (SEBS) , epoxy resin, hydrocarbon resin, polyester resin, urea resin, silicone resin, polyphenylene ether resin, modified polyphenylene ether resin, liquid-crystal polymer resin, and combinations thereof.
The dielectric film of claim 11, wherein the polymer is a polyimide and the polyimide is derived from a polyamic acid created at least in part by contacting one or more dianhydride components with one or more diamine components.
The dielectric film of claim 12, wherein the dianhydride component is selected from a group consisting of from the group consisting of pyromellitic dianhydride (PMDA) ; 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA) ; 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride; , 3, 3', 4, 4'-diphenylsulfonetetracarboxylic dianhydride; 4, 4'- (hexafluoroisopropylidene) diphthalic anhydride (6FDA) ; cyclobutane-1, 2, 3, 4-tetracarboxylic dianhydride (CBDA) ; cyclopentanetetracarboxylic dianhydride (CPDA) ; and combinations thereof.
The dielectric film of claim 12 or 13, wherein the diamine component is selected from a group consisting of 3, 4'-oxydianiline; 4, 4'-oxydianiline (ODA) ; 1, 4-diaminobenzene; 1, 3-diaminobenzene; 4, 4'-diaminophenyl; 2, 2'-bis (trifluoromethyl) -1, 1'-biphenyl-4, 4'-diamine (TFDB) ; and combinations thereof.
The dielectric film of any one of claims 10 to 14, wherein the film has a thickness ranging from 10 to 2000 μm.
The dielectric film of any one of claims 10 to 15, further comprising a substrate selected from the group consisting of copper, silicon, silicon nitride, aluminum, gold, silver, polyimide, and epoxy mold compound.
The dielectric film of any one of claims 10 to 16, wherein the film has a D _k ≤ 3 and a D _f ≤ 0.004 at 20 GHz.
An electronic device having at least one layer comprising the dielectric film of any one of claims 10 to 17.