GB2200128A

GB2200128A - Crosslinkable polyphenylene oxide resin composition

Info

Publication number: GB2200128A
Application number: GB08729432A
Authority: GB
Inventors: Shuji Maeda; Takaaki Sakamoto; Munehiko Ito; Takahiro Heiuchi; Takayoshi Ozeki
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1986-12-23
Filing date: 1987-12-17
Publication date: 1988-07-27
Anticipated expiration: 2007-12-17
Also published as: DE3743964C2; GB8729432D0; GB2200128B; FR2608616A1; DE3743964A1; FR2608616B1

Description

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22O0128 Title:

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POLYPHENYLENE OXIDE RESIN COMPOSITION This invention relates to a polyphenylene oxide resin composition in which an inorganic filler is included.

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The polyphenylene oxide resin composition of the kind referred to can be formed into a film which is utilizable for fabricating a laminate excellent in the heat resistance, chemical resistance and physical strength and having an optional relative dielectric constant.

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Generally, the resin composition based on polyphenylene oxide (which shall be hereinafter referred i0 to as "PPO") is a material relatively high in the glass transition point and low in the relative dielectric constant and dissipation factor, and its utility has been highly appreciated in these years. An example of the PPO resin of the kind referred to is disclosed in U.S. Patent No. 4,059,568", which is excellent particularly in the high frequency characteristics and is thus regarded as showing highly excellent result when used as a material for the laminate which is well utilizable in the extrahigh frequency band. This composition shows, on the other hand, the thermoplasticity, which leaves problems of poor resistance to heat and organic solvent.

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In improving the resistance to heat and solvent, in this case, the optimum and most reliable measure will be i0 to have the composition crosslinked as proposed in an earlier U.S. Patent Application No. 840,753 of the present inventors, (or corresponding British Patent Application No 86 06764 or German Patent Application P 36 07 664.4), wherein a PPO resin composition comprises PPO, at least one of crosslinking monomer and polymer, and an initiator.

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According to this U.S. Patent application, the PPO resin composition can oe made excellent in the high frequency characteristics and also sufficiently satisfactory in the heat resistance.

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In designing a high frequency circuit employing a rinted circuit substrate including a laminate of the PPO resin composition which is excellent in the high frequency characteristics, on the other hand, it is further demanded that the substrate will be of a relative dielectric constant matching with desired dimension, frequency band and so on of the circuit.

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20 The primary aim of the present invention is, therefore, to provide a PPO resin composition which is utilizable for preparing a laminate having, in addition to the desired heat resistance, a desired level of the relative dielectric constant matching with required circuit dimension, frequency band and the like conditions as well as high chemical resistance and physical strength.

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According to the present invention, this aim can be realized by providing a PPO resin composition comprising PPO and at least one of a crosslinking polymer and a i0 - 4 " wherein crosslinking monomer, an inorganic filler is contained additionally.

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Other objects and advantages of the present invention shall be made clear in following description of the invention detailed with reference to preferred examples of the invention, but it should be appreciated that the intention is not to limit the present invention only to include all arrangement the examples disclosed but to rather modifications, alterations and equivalent possible within the scope of appended claims.

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While the polyphenylene oxide resin composition of the presen{ invention includes an inorganic filler in addition to polyphenylene oxide (PPO) and at least one of the crosslinking polymer and crosslinking monomer, PPO is a resin also called as polyphenylene ether, which is represented by such a general formula as i R R) n o where R is a hydrocarbon radical having hydrogen or carbon of 1 to 3 in number, and the respective R's may be all the same or different. Such a method as disclosed, for example, in U.S. Patent No. 4,059,568 will allow this resin synthesized, and one which can be enumerated as PPO will be poly-(2,6-dimethyl-l,4-phenylene oxide).

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The particular PPO may be prepared through a process of, for example, having 2,6-xylenol reacted for oxidative i0 x -- 5 -- coupling with a gas including oxygen as Well as methanol, under the presence of a catalyst to obtain poly-(2,6-dimethyl-l,4-phenylene oxide), but the process is not limited only to this. For the catalyst, the one containing copper (I) compound, N, N'-di-tert-dibutyl ethylenediamine, butyl dimethylamine and hydrogen bromide may be used. Methanol is used in a polymeric solvent in which 2 to 15 weight % of water is added to reactive mixture so that the total of methanol and water will be 5 to 25 weight %. While not required to be limited, PPO should preferably be a polymer of 50,000 in the weight-average molecular weight (Mw) and the molecular-weight distribution Mw/Mn = 4.2 (where Mn is the number-average molecular weight).

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As the crosslinking polymer, there may be enumerated such members as 1,2-polybutadiene, 1,4-polybutadiene, styrene-butadiene copolymer, modified 1,2-polybutadiene (maleic modified, acrylic modified and epoxy modified), rubbers and the like, which may be used alone or in a mixture of two or more of them. Polymerization state may be either elastmeric or rubbery, but it is prefrable that, for the purpose of improving the film-forming property, the crosslinking polymer is in a rubbery state of high- molecular weight. From the viewpoint of the improvement in the filmforming property upon formation of a film from the PPO resin composition of the presen invention, it is preferable to employ polystylene which is contributive to the improvement in the film-forming i0 property of the composition of high-molecular weight.

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As the crosslinking monomer, there may be enumerated I) such acrylates as ester acrylates, epoxy acrylates, urethane acrylates, ether acrylates, melamine acrylates, alkyd acrylates, silicon acrylates and the like; 2) such polyfunctional monomers as triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate and the like; 3) such monofunctional monomers as vinyltoluene, ethylvinyl benzene, styrene, para-methylstyrene and the like; and 4) polyfunctional epoxies; which may be employed alone or in a mixture of two or more of them, while not required to be limited to them. From the viewpoint of the compatibility withl PPO, as well as the film-forming property, crosslinking ability, heat resistance and dielectric properties, it is preferable to employ either one or both of triallyl cyanurate and triallyl isocyanurate. While these two are isomeric to each other in their chemical structure, they may be used alone or concurrently since they are substantially of the same film- forming property, compatibility, solubility, reactivity and so on.

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The foregoing crosslinking polymer and/or the crosslinking monomer can improve PPO in the heat resistance and so on without impairing its inherent properties with their crosslinking or setting ability. While they may be used alone, it should be preferable to use both of them concurrently in view of resultant improvements in the properties.

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According to a remarkable feature of the present invention, an inorganic filler of a relatively higher relative dielectric constant is added to PPO which is lower in the relative dielectric constant and also in the dissipation factor and is an inexpensive resin, whereby the PPO resin composition of an optional relative dielectric constant can be prepared, and this composition is contributive to a fabrication of a laminate having also an optional relative dielectric constant.

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As the inorganic filler, there may be enumerated such substances as aluminum oxide AI203, silicon dioxide SiO2, titanium dioxide TiO2, glass fiber, glass tip, barium titanate BaTiO3, lead titanate PbTiO3, strontium titanate SrTi03, calcium titanate CaTiO3, magnesium titanate MgTiO3, barium zirconate BaZrO3, lead zirconate PbZrO3, K20-PbO-SiO2 series glass, sintered member of lead titanate and lead zirconate, and glassy state solid solution, which may be used alone or in a mixture of two or more, while not required to be limited only to them. In obtaining the sintered member, it may be possible to first mix raw materials therefor and then to fire them, or to have the materials sintered separately and then to mix them. In either case, the member is to be used eventually in powdery state.

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In order that the PPO resin composition of a desired relative dielectric constant is obtained, the inorganic filler employed should preferably be of a large relative dielectric constant which should be desirably more than i0 m 8 - i0. For such inorganic filler of the relative dielectric constant more than i0, there may be enumerated such materials as, for example, titanium dioxide ceramics, barium titanate ceramics, lead titanate ceramics, strontium titanate ceramics, calcium titanate ceramics, bismuth titanate BiTiO3 or Bi4Ti3012 ceramics, magnesium titanate ceramics, lead zirconate ceramics and the like, which may be employed alone or in a mixture of two or more. Further, the filler may be a mixture of two or more of these ceramics or of two or more of raw material compounds of these ceramics, the mixture being sintered and finely crushed. While these materials shall be referred to as "ceramics" hereinafter for convenlence sake, it should be appreciated that the inorganic fillers of more than I0 relative dielectric constant are not limfted to those which have been enumerated in the above.

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It is preferable that, by the firing of the materials for the inorganic filler, hydrate, hydroxide, carbonate and the like are removed so that the relative dielectric constant of the inorganic filler can be thereby stabilized, the affinity to resins is improved and the heat resistance is made excellent. Further preferable is to render the firing conditions to be constant. In the above materials enumerated, titanium dioxide ceramics are to, include, in the sense of the composition, such series which containing only TiO2 or TiO2 and a small amount of an additive or additives that maintain the crystalline structure of TiO2 as being the main component. This also i0 -- 9 -- applies to all other dielectric ceramics. Further, while titanium dioxide is the substance represented by TiO2 and includes various ones of different crystalline structure, the present invention is to employ as the inorganic filler only ones which showing the structure of rutile.

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Not only the composition, on the other hand, the inorganic filler is made different in the dielectric properties by the firing (or sintering) and conditions for the crushing (particle size and particle-size distribution), and the firing condition is also variable. The firing should preferably be carried out with respect to the ceramic rather in the powdery state without addition of any organic binder, than in a molded state of the powdery ceramic as pressed thereinto, since any organic binder added renders the resultant sintered member to De too hard to crush so as not to be optimumly controlled inthe average particle size and particle-size distribution. Further, the foregoing firing is to include such heat treatment as calcining and the like which generally carried out for the purpose of the sintering. Examples of the firing conditions are as shown in following Table 1 while not required to be limited thereto:

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Type of Ceramic:

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TiO2 ceramics BaTiO3 ceramics TABLE 1 Firing Temperature:

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1,300 - 1,400q t! Firing Time:

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2 - 5 ho s It - i0 - PbTiO3 cermnics SrTiO3 ceramics BiTiO3 or Bi4Ti3Ol2 ceramlcs [JjTi03 ceramics PbZrO3 ceramics BoZrO3 cernics 900 - 1,000 C 1,300 - 1,400 C t! I! 900 - 1,000QC 1,300 - 1,400 C I! t! I! I! It I! i0 Since the thus fired ceramics some of which become very hard are different in their characteristics depending on the particle size, they are crushed preferably until a fixed particle size,desired is reached. Since the ceramic's.particle size also affectslargely the possibility of obtaining a homogeneous PPO resin composition, further, the ceramics should preferably be crushed own to a size which gives no influence on the characteristics of such final products as molded articles of the PPO resin-composition so as to be, optimumly, fine particles of less than about 50 p m. In practice, for convenience sake in manufacturing course, it is preferable to set the size in a range of 0.1 to 20 pm or preferably 0.5 to 7 pm, optimumly 1.0 to 2.0 pm, in order to avoid any handling difficulty likely to occur when the size is too fine. Preferred particle size distribution of the inorganic filler should be a combination which is i00.0 weight % in total of 12-22 weight % for 1.0 m particles, 53-73 weight % for particles larger than 1.0 p m and smaller than 2.5 p m, 7-17 weight % for particles larger than 2.5 pm and smaller than 4.0 pm, less than i0 weight % - ii - for particles larger than 4.0 m and smaller than 5.5 m, and less than i0 weight % for particles larger than 5.5 m and smaller than 7.0 m, excluding thus any particles larger than 7.0 u m, while not required to be limited thereto.

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The inorganic filler may be employed without being subjected to any special surface treatment.

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In order to improve in the heat resistance and water absorption of eventually set resin composition, however, it is preferable to perform a surface treatment by means of silane, titanium or the like series coupling agent.

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With the use as the inorganic filler of such dielectric materials high in the relative dielectric constant as has been partly referred to in the above, the PPO resin composition can be elevated in the relative dielectric constant in the final set product, and this relative dielectric constant may even be adjusted over a wide range by properly adjusting the type and amount of the dielectric material employed. That is, it should be appreciatedthat the inorganic filler can be utilized as an agent for adjusting the relative dielectric constant.

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The upper limit of the composition ratio of the inorganic filler in the PPO resin composition should be immediately before reaching a ratio with which the set product of the PPO resin composition starts becoming porous or being deteriorated in the strength.

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Further, the PPO resin composition according to the present invention should preferably comprise i0 to 95 i i0 weight parts, optimumly 20 to 80 weight parts of PPO, 1 to 90 weight parts of at least one or both of the crosslinking polymer and crosslinking monomer, and 1 to 200 weight parts of the inorganic filler or preferably 40 to 100 weight parts when employed as the relative dielectric constant adjusting agent, while not limited only thereto. When the ratio of the crosslinking polymer and/or the crosslinking monomer is less than the above, there arises a risk that the adhesion and the like become insufficient while the ratio exceeding the above causes the inherent properties of PPO resin not to be fully shown. When the ratio of the inorganic filler does not reach the above, no effect of the addition of the inorganic filler can be shown while the ratio exceeding the above may happen to result in an occurrence of porous state or deterioration in the strength.

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Now, provided that an organic binder comprises 70 parts by weight of PPO, 15 parts by weight of styrene-butadiene copolymer, 14 parts by weight of triallyl isocyanurate and 1 part by weight of dicumyl peroxide, it shows a relative dielectric constant of 2.6 and a dissipation factor of 0.002 (at 23 C and 1 MHz).

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When 255 parts by weight of barium titanate are added to partslby weight of this organic binder, the resultant composition Will have a relative dielectric constant of 9.2 and a dissipation factor of 0. 009 (at 23 C and 1 MHz). In consideration of the relative dielectric constant 2,000 of barium titanate itself, the relative dielectric i0 constant of the composition obtained can be adjusted in practice by means of the composition ratio (volume fraction) of barium titanate, that is, of the inorganic filler. In other words, the composition ratio of the inorganic filler with respect to the PPO resin composition should properly be selected for obtaining a desired relative dielectric constant.

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When, in particular, a flaky inorganic filler is employed, the PPO resin composition can be made excellent in the dimensional stability, solvent resistance and warpage prevention in the eventual set product of the composition. As the flaky inorganic filler, such flaky glass as a micro glass flake manufactured by a Japanese firm Nippon Glass Fiber K.K., which being flat glass pieces of 2 to 3 u m thick and 10 to 325 mesh in particle size, and/or such mica as a dymonite manufactured by a Japanese firm ToPY KOGYO K.K., which being microfine micaòas being 5 to i00 mesh, may be employed. For the mica, it is preferable to employ commonmica in respect of the electric Characteristics, but is not to be limited thereto.

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The flaky inorganic filler should preferably oe less than 80 mesh in size, since with a size above 80 mesh, the filler becomes likely to sediment when the PPO resin composition is made into a solution and there arises a risk that the dispersion properties in the solution become deteriorated. Further, the flaky inorganic filler should preferably be of an average thickness less than 3 m i0 and/or of an aspect ratio less than i00, since the average thickness larger than 3 m and the aspect ratio larger than 100 may cause to'arise such a risk that, in forming the PPO resin composition into a sheet by means of a casting as will be referred to later, the drying rate becomes low to deteriorate the workability and to lower the solid state property. From the viewpoint of improvement in the dimensional stability of the eventual molded product of the PPO resin composition according to the present invention, on the other hand, it is desirable that the flaky inorganic filler will have a thickness of more than 1 m and/or an aspect ratio of more than 10. It should be appreciated that the flaky inorganic filler acts as a skeleton of resin in the set product of the PPO resin composition to improve the strength of the set product, and also functions with the flaky shape to prevent such chemicals as a solvent from soaking into the product for contributing to the dimentional stability.

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The foregoing flaky inorganic filler should desirably be added at a ratio of i to 80 parts by weight to the PPO resin of a composition of I0 to 95 parts by weight of PPO (preferably 20 to 80 parts by weight), 5 to 50 parts by weight of crosslinking polymer (preferably 5 to 45 parts by weight) and/or 1 to 20 parts by weight of crosslinking monomer, while it should not be limited thereto.

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Further, an initiator is normally added to the PPO resin composition containing the inorganic filler. As the initiator, such substances as follows may be selectively i0 employed depending on whether the PPO resin composition should be ultraviolet curing type or thermosetting type, while it should not be limited only to them. For the light initiator of the ultraviolet curing type which generates radicals upon incident of ultraviolet ray, there may be enumerated: benzoin, benzine, allyldiazonium fluoroborate, benzilmethylketal, acetophenone, benzoil-isobutyl ether, trichloroacetophenone, monooxime, biacetyl, Michler's ketone, azobisisobutyronitrile and the like; and, for the thermosetting type initiator which generates radicals upon being heated, there may be enumerated such peroxides as 2,2-diethoxy- p-tert-butylbenzil(O-ethoxycarbonyl)-aacetophenone, benzophenone, tetramethylthiuram sulfide, peroxide, benzoil 2,5-dimethyl-2,52,5-dimethyl-2,5-di(tert-butyl-peroxy)hexane,,,-bis-(tert-butyl-peroxy-misopropyl)benzene (or called as 1,4 (or 1,3)-bis (tert-butyl-peroxy-isopropyl)benzene, and the like, as well as l-hydroxy-cyclohexyl-phenylethane, 2-hydroxy2-methyll-phenyl-propane-l-one, l-(4-isopropylphenyl)-2hydroxy-2-methylpropane-l-one, 2-chlorothioxanthone, methylbenzoylformate, 4,4-bis(dimethylamino)benzophenone (Michler' ketone), benzoinmethyl-ether, methyl-Obenzoylbenzoate, a-acyloxime-ester, biscumyl (by a Japanese firm Nippon Yushi K.K.) and the like; which may be used respectively alone or in a mixture of two or more dicumyl peroxide, tert-butylcumyl peroxide, di-tert-butyl-peroxide, di(tert-butyl-peroxy)hexyne-3, i0 of them. It is also possible to concurrently employ ones respectively selected from both of the ultraviolet curing type and thermosetting type groups.

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l Composition ratio of the initiator should preferably be 0.i to 5 parts by weight (desirably 0.i to 3 parts by weight) with respect to the PPO resin composition of the foregoing preferred composition ratio. When the ratio does not reach this range, there arises a risk that the setting of the PPO resin composition becomes insufficient while the ratio exceeding this range may cause a risk of giving ill influences on the solid state properties of the resin composition after being set.

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The respective materials for the PPO resin composition of the present invention are normally dissolved in a solvent (the inorganic filler normally being not solved), dispersed therein and mixed With each other upon which the PPO resin composition should preferably be 5 to 50 parts by weight solution (or in a range of I0 to 30 weight % in the solid resin content with respect to the solvent), and the PPO resin composition can be obtained by removing the solvent after the mixing. For the solvent, such hydrocarbon halides as trichloroethylene, trichloroethane, chloroform, methylene chloride, chlorobenzene and the like; such aromatic hydrocarbons as benzene, toluene, xylene and the like; acetone; carbon tetrachloride; and so on may be enumerated, while they maybe employed alone or in a mixture of two of more of them. In particular, trichloroethylene may be used as the optimum solvent, but it is not required to limit the solvent only to those enumerated. For the mixing, any one of various known measures may be employed.

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The thus solved and mixed materials for the PPO resin composition may be formed into a set product through a so-called casting process in which the mixed materials are made into a thin film as being subjected to a flow casting i0 or coating and are then dried to remove the solvent. While the composition materials may be set through a calendering process, the use of the casting process is advantageous in respect of required costs and also allows it possible to form the PPO resin composition at a lower temperature. While the set product obtained through such casting process is normally in the form of filmy sheet, it is of course unnecessary to limit the form of the product only to the sheet.

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The particular PPO resin composition can be employed for preparing a printed circuit wiring substrate and the like. In applying the composition to such substrate, it is desirable to prepare a sheet of the PPO resin composition and/or a base member impregnated with this PPO resin composition (this base member shall be hereinafter referred to as "prepreg") and it is made easy to manufacture a laminate of any desired thickness.

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In preparing the filmy sheet through, for example, the casting process, practically, the materials for the PPO resin composition are solved in such a solvent as in the foregoing preferably at a ratio of 5 to 50 parts by weight (the inorganic filling being dispersed without being solved) and are mixed into a solution, which is then cast (or applied) to be, for example, 5 to 700 u m (preferably 5 to 500 m) on a planished iron plate, casting carrier film or the like and is then dried sufficiently to remove the solvent. Here, the term "sheet" should include those which are grasped as film, tape and so on and should not be specifically defined in respect of the spreading or the length in a plane perpendicular to the thickness direction. For the casting carrier film to be used in t|]e casting process, such films insoluble to the foregoing solvent and mold-release treated as polyethylene terephthalate (hereinafter referred to as "PET") film, polyethylene film, poiypropylene film, polyester film, polyimide fiim and the like may preferably be used while not limited to them only. The cast (or applied) solution of the PPO resin composition on the casting carrier film is dried practically as subjected to an air-drying and/or hot air processing or the like to remove the solvent. The drying temperature is preferably so set that the upper limit will be below the boiling temperature of the solvent or, in the case of drying as left on the carrier film, lower than the heat-resistant temperature of the carrier film and the lower limit will be set in view of required drying time or processing easiness. When, for example, trichloroethylene and PET film are employed respectively as t)e solvent and carrier film, the drying temperature range is set to:be from the room temperature to 80 C. The higher the drylng temperature set within this range, the shorter the drying time obtainable.

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The prepreg can be prepared in any of a variety of processes. For example, the materials for the PPO resin composition are completely solved in such a solvent as in the foregoing, except the inorganic filler, preferably at a ratio of 5 to 50 parts by weight, and the base member is dipped into this solution to be impregnated therewith. In this case, it may be sufficient to only remove the solvent by means of the drying or the like, or to have the solution intermediately set from A stage to B stage. The content of the PPO resih composition in the thus prepared prepreg should preferably be 30 to 80 weight %, while not limited thereto. For the base member, such weavings which can be impregnated with resin as glass cloth, alamid cloth, polyester cloth, nylon cloth and the like, matted materials and/or unwoven or the like fabric materials of the same stuffs as the foregoing weavings, such papers as craft, linter and the like papers, and so on, while not limited to them. With such process, the prepreg can be easily prepared relatively at a low temperature without requiring any melting of resin materials.

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The set product of the PPO resin composition prepared as has been disclosed can be further improved in the tensile strength, impact strength, tearing strength, heat resistance and so on by means of a heat crosslinking with a radical crosslinking, initiator employed, radioactive-ray-initiated light-initiated crosslinking or i0 the like. When the PPO resin composition of the present invention is formed into the sheet member, the composition may be utilized not only for preparing the laminate but also for many other purposes including a preparation of adhering sheet and the like.

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The laminate employing the sheet member of the PPO resin composition according to the present invention can be formed into ones having on one or both surfaces a metallic foil, ones having no metallic foil, and so on. When such sheet members are prepared through the foregoing casting process, the drying should be carried out at a temperature which is lower than the decomposition temperature of the added initiator and sufficiently higher than the boiling point of the employed solvent, so that any residual solvent can be completely removed.

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A required number for a predetermined laminate thickness of the sheets and/or the prepregs of the PPO resin composition according to the present invention as well as the metallic foils as required are combined and stacked and are subjected to a heat-press or the like so that the resin composition will melt and bond mutually between the sheets, between the sheets and the prepregs, mutually between the prepregs, between the sheets and the metallic foils, and between the prepregs and the metallic foils, and the laminate can be obtained. With this melt bonding, there can be provided a firm adhesion between respective layers of the laminate and,with the presence of the radical initiator which is heated here, the i0 crosslinking reaction can be thereby promoted to allow a more stiff adhesion can be attained. The cross!inking reaction can be also carried out by means of the ultraviolet ray irradiation as has been briefly described. When, further, the heat or light initiated crosslinking cannot be carried out, the crosslinking may be promoted by means of an irradiation of radioactive ray, which means can even be performed after the heat or light initiated crosslinking reaction. promoting means, an With any one of these crosslinking adhesion excellent in the heat resistance can be realized between the respective sheets, prepregs, sheet and prepreg, sheet and metallic foil and prepreg and metallic foil in the thus obtained laminate.

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When the sheet and prepreg are concurrently employed, here, it is preferable that they are stacked in symmetrical relationship in stacking direction in respect that the warping or the like can be thereby prevented from occurring even when such a secondary working as, for example, etching process is performed after mold forming of the laminate, and it is also preferable that the sheet is arranged to be disposed at every adhesive interface with respect to the metallic foil so as to increase the adhesive force, though the invention is not to be limited thereto. When the heat melting of the sheet is utilized to adhere the sheet and metallic foil each other, the heat pressing temperature for the liminate should preferably be in a range of about 160 to 300 C so as to be above the glass transition point of the sheet. In the case of the i0 set product of the PPO resin composition, in general, there can be seen a tendency that the resin is likely to flow to some extent prior to being hardened and thus shows an excellent fusion bonding to the metallic foil, and any special adhesive agent is not required but may of course be employed.

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The foregoing metallic foil employed in the laminate should preferably be such ones which are flat and smooth at adhering surface in rendering the low transmission loss as, for example, copper foil and aluminum foil, which will form a metallic layer acting as conductor layer in the laminate. The metallic layer may be formed by means of a vapor deposition, or any one of subtractive, additive or the like processes, the latter including full-additive and semi-additive processes, so that metal conductor layers forming any desired electric circuit, electrodes and so on will be properly formed.

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The heat pressing or the like for the stacked sheets and so on is performed under properly selected conditions for achieving excellent adhesion between the respective sheets, sheets and prepregs, respective prepregs, sheets and metallic foils, metallic foils and prepregs and so on as well as desired thickness adjustment of the laminate. In performing the heat-crosslinking of the PPO resin composition of the present invention by inserting it in a dryer, the heating temperature and time should be properly selected, preferably, depending on the type of the initiator since the crosslinking reaction is dependent on i0 reaction temperature and so on of the initiator so that, for example, the heating temperature will be 150 to 300 C and the heating time will be about i0 to 60 minutes, as the preferable conditions, under which the pressure for heat pressing should be, for example, about 50 kg/cm2. The laminate may alternatively be formed by preliminarily heat-pressing a stack of the predetermined required number of the sheets and/or prepregs, stacking the metallic foil or foils on one or both surfaces of the preliminarily heat-pressed laminate and further heat-pressing them again to obtain a metal clad laminate.

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It should be readily appreciated by any skilled in the art from the foregoing disclosure that such set product of the PPO resin composition according to the present invention as the laminate and so on obtained as in the above is excellent not only in the heat resistance but also in the chemical resistance and physical strength, without impairing the inherent properties of PPO in respect of the low relative dielectric constan:t and dissipation factor, and is further excellent in that the solvent resistance as well as the solid state properties are improved by the addition of the inorganic filler with any warpage restricted to be the minimum, and the relative dielectric constant can be set at any optional value while maintaining the dissipation factor of the composition to be low by properly selecting the type and amount of the inorganic filler. EXamPLE i:

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i0 In a reactor having a vacuum means and of a capacity of 2 liters, 100g of PPO, 40g of styrene-butadienecopolymer (SOLPREN T406 by Japanese manufacturer ASAHI KASEI KOGYO K.K.), 40g of triallyl isocyanurate (TAIC by Japanese manufacturer NIPPON KASEI K.K.) and 2g of dicumyl peroxide were placed, 750g of trichloroethylene (TRICHLEN by Japanese manufacturer TOA GOSEI KAGAKU KOGYO K.K.) was further added thereto, and they were sufficiently stirred until a homogeneous solution was obtained. Thereafter, 260g of powdery aluminum oxide of average particle size of 1 to 2 m was added and stirred to be uniformly dispersed in the solution. Thereafter, the solution was defoamed, thus obtained PPO resin composition solution was applied onto a PET film by means of a coater to be 500 m thick, which was then dried at 50 C for about 10 minutes, thus obtained film was released from the PET film, and was again dried at 120 C for 30 minutes to completely remove trichloroethylene, and a sheet made of the PPO resin composition was obtained. The thickness of this sheet was about 150 m. Four of this sheet were stacked and subjected to a heat pressing at heating temperature of 190 C under a pressure of 50 kg/cm2 for 30 minutes to have them completely set, and a laminate was thereby obtained. EXAMPLES 2 to 5:

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Different laminates were obtained in the same manner as in Example 1 except for variation in such composition ratio and trichloroethylene amount as shown in following I0 Table 2, in which titanium dioxlde employed was a product by a Japanese manufacturer FUJI TITAN KOGYO K.K. of an average particle size i to 2 um. EXAMPLE 6:

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In a reactor having a vacuum means and of a capacity of 3 liters, 140g of PPO, 40g of styrene-butadiene copolymer (SOLPREN T406 by ASAHI KASEI), 40g of triallyl isocyanurate (TAIC by NIPPON KASEI) and 3g of dicumyl peroxide were placed, 850g of trichloroethylene (TRiCHLEN by TOA GOSEI) was further added, and they were sufficiently stirred until a homogeneous solution was obtained. Thereafter, 280g of powdery aluminum oxide of average particle size 5 to 6 m (AM-21 by a Japanese manufacturer SUMITOMO ALUMINUM SEIREN K.K.) was added to the solution, which was further stirred to have the powder uniformly dispersed in the solution. Thereafter, the solution was defoamed, and thereby obtained PPO resin composition solution was applied by means of a coater onto a PET film to be a layer of a thickness of 500 um. The applied solution was dried at 50 C for about 10 minutes, thus produced film was released from the PET film and further dried at 120 C for 30 minutes to have trichloroethylene removed completely, and a sheet of PPO resin composition was obtained. The thickness of this sheet was 120 m. Eight of the thus obtained sheets were stacked, with an electrolytic copper foil of 35 m thick laminated onto each of top and bottom surfaces of the stacked sheets, which were heat-pressed under conditions i0 of heating temperature at 200 C and applied pressure of 50 kg/cm2 for 30 minutes to completely set, and thus a laminate was obtained.

.DTD:

EXAMPLES 7 to 10:

.DTD:

Different:laminates were obtained in the same manner as in Example 6 except for variation in the composition ratio and trichloroethylene amount as shown also in Table o COMPARATIVE EX6PLES 1 & 2:

.DTD:

Different laminates were further obtained in the same manner as in Examples 1 and 6, respectively, except for such variation in the composition ratio and trichloroethylene amount as shown also in Table 2.

.DTD:

In Table 2, the solid state properties of the respective laminates according to Examples 1 to i0 and Comparative Examples 1 and 2 are also shown.

.DTD:

TABLE 2 .DTD:

RatioCg) EhpleS 1 2 3 100 6 7 8 9 i0 1 2 Cmssl'k. Crcssi'k.

.DTD:

4O 4O i00 i00 4O 4O 40 40 40 40 40 40 40 40 40 40 40 40 InitJah 3 2 4O Ircrg. A A A A A C C C C C fille 4 260 670 1350 50 i00 280 500 1100 1700 2000 B B 230 330 2 2 2 2 2 2 2 2 2 2 i0 ethyls (g[ Relative dielect. o:. of. fill, (1 So]_id state es:

.DTD:

750 850 950 750 850 850 1200 1400 1600 1800 9.5 9.5 9.5 8.0 7.5 9.5 9.5 9.5 9.5 9.5 750 850 w 2O 2O el. dielec. 4.20 5.30 6.10 7.50 10.80 3.94. 4.73 5.51 6.17 6.48 2.60 2.65 o st.

.DTD:

DissJp'ft'.0012.0015.0011 [0020.0022.0021.0025.0023.0027.0029.0011,0012 (]M,23 C) Solcing hs_-t rcsi. 120< 120< 120< 120< 120< 60 60 120< 120< 120< (see.) s oth (kg/'an') 2.1 2.0 2.2 2.1 2.1 2.1 2.1 2.0 1.9 1.5 2.1 2.3 a< a( 0/9 OuT OJT OuT resist. 5 Alkali CK (I< EK EK (I< CK CI< O< CI< OK EK resist. 6 x 5.5 4.0 2.5 5.2 3.7 8.5 8.1 6.9 5.3 4.2 9.2 9.5 esns. 6.5 4.5 3.0 6.4 4.5 8.1 8.3 6.7 4.9 4.1 8.7 8.1 u/f. _ (xl/l)---0-b" -_z 14.013.0 10.5 13.5 10.5 15.9 15.5 12.3 ii.0 9.8 15.0 16. 4 In the above Table 2, i is styrene-butadiene copolymer; 2 is triallyl isocyanurate; 3 is dicumyl peroxide; in 4, A is aluminum oxide of average particle size 1 to 2 m, B is titanium dioxide of average particle size 1 to 2 m and C is aluminum oxide of average particle size 5 to 6 m; 5 is observed appearance of the laminate after being dipped in boiling trichloroethylene for 5 minutes; and 6 is observed appearance of the laminate after being dipped i0 in an alkaline solution kept at 40 C.

.DTD:

As will be clear from the above Table 2, the respective laminates employing the sheet made of the PPO resin composition of the present invention according to Examples 1 through i0 are low in the dissipation factor with an optional relative dielectric constant and, while showing substantially equal peeling strength at normal temperature and alkali resistance to those of Comparative Examples 1 and 2 without deterioration, they have been improved in the soldering heat resistance and thermal expansion coefficient as compared with those of Comparative Examples 1 and 2. That is, the laminates of Examples 1 through 10 have been made excellent in the heat resistance and also in the dimentional stability. Further, where the same inorganic filler is employed, the relative dielectric constant has shown to be increased as the composition ratio of the filler was increased. The effect of the filler in elevating the relative dielectric constant has been more remarkable in titanium dioxide than aluminum oxide. It has been also found that, by varying the type and amount of the inorganic filler, the relative dielectric constant of the PPO resin composition can be varied to a large extent EXAMPLE ii:

.DTD:

In areactor of 2 liters capacity and having a vacuum means, 100g of PPO, 30g of styrene-butadiene copolymer (SOLPREN by ASAHI KASEI), 40g of tria!lyl isocyanurate (TAIC by NIPPON KASEI) and 2g of - 29 2,5-dimethyl-2,5-di(tert-butyl-peroxy)hexyne-3 (PERHEXYNE 25B by a Japanese manufacturer NIPPON YUSHI K.K.) were placed, 750g of trichloroethylene (TRICHLEN by TOA GOSEI) was added thereto, and they were sufficiently stirred until a homogeneous solution was obtained. Thereafter, 150g of powdery barium titanate ceramic of average particle size 2 m was added and the solution was stirred by means of a ball mill for about 24 hours to have the ceramic dispersed uniformly in the solution. A defoaming was carried out with respect to the solution, and obtained PPO resin composition solution was applied with a coater onto a PET film to be of a layer of 500 m thick. After drying it at 50 C for about I0 minutes, thereby produced film of the composition was released from the PET film, the released film was further dried at 170 C for 20 minutes to completely remove trichloroethylene, and a sheet comprlslng the PPO resin composition was obtained. The sheet was of a thickness of about 150 u m. Four of the thus obtained sheets were stacked and heat- pressed under such conditions of heating temperature at 220 C and at a pressure of 50 kg/cm2 for 30 minutes, to have the sheets completely set, and a laminate was obtained. EXAMPLES 12 to 23:

.DTD:

Different laminates were obtained substantially through the same steps as in Example ii, except for such variation in the composition ratio and trichloroethylene amount as shown in following Table 3.

.DTD:

EXAMPLE 24:

.DTD:

i0 In a reactor of 2 liters capacity and having a vacuum means, 800g of trichloroethylene (TRICHLEN by TOA GOSEI) was placed, 40g of PPO, 40g of styrene-butadiene copolymer (SOLPREN T460 by ASAHI KASEI), 120g of triallyl isocyanurate (TAIC by NIPPON KASEI), and 6g of 2,5-dimethyl-2,5di(tert-butyl-peroxy)hexyne-3 (PERHEXYNE by NIPPON YUSHI) were added thereto, and they were sufficiently stirred until a homogeneous solution was obtained. 130g of powdery barium titanate (BaTiO3) ceramic of average particle size of 2 m was added to the solution, they were further stirred to have the ceramic uniformly dispersed within the solution. A defoaming was carried out, a glass cloth (i00 g/m2) was dipped in the thus obtained PPO resin solution to have the cloth impregnated with the solution, the glass cloth was then taken out of the solution and subjected to a drying at 50 C for i0 minutes and further at i30 C for about 20 minutes, and a prepreg was obtained. Four of the thus obtained prepregs were stacked and subjected to a mold forming by a molding press under such conditions as a heating temperature at 195 C and a pressure of 10 kg/cm2, and a laminate was obtained. EXAMPLES 25 to 37:

.DTD:

Various liminates were obtained substantially through the same steps as in iExample 24, except for such variation in the composition ratio as shown in Table 3. EXAMPLE 38:

.DTD:

A glass clotl was dipped sufficiently within the PPO i0 resin composition solution of Example ii, the cloth was taken out of the solution and dried at 50 C for about 10 minutes and further at 130 C for about 20 minutes to completely remove trichloroethylene and a prepreg of the glass cloth impregnated with the PPO resin composition was obtained. Two of such prepregs and three of the sheets obtained through Example ii were stacked respectively alternately and subjected to the heat pressing under the same conditions as in Example ii, and a laminaúe was obtained.

.DTD:

COMPARATIVE EXAMPLES 3 & 4:

.DTD:

Different laminates were obtained through the same steps as in Examples ii and 24, except for such changes in the composition ratio as shown in Table 3.

.DTD:

In Table 3, the solid state properties of the respective laminates obtained through Examples II through 38 as well as those of Comparative Examples 3 and 4 are also shown.

.DTD:

TABLE 3 - I .DTD:

Ii 12 13 14 15 16 17 18 19 20 21 22 23 i00 100 i00 100 100 i00 I00 i00 100 i00 100 100 100 l'k 30 pol erCll) 30 30 30 30 30 30 30 30 30 40 40 40 40 40 40 40 40 40 InitiatcrC) 2 2 2 2 2 2 2 2 2 2 2 2 i0 - 32 Inlg. fill. D150 D250 D330 El50 D 80 F150 DI00 D 60 KI00 L 50 t250 {00 (1200 ('14) El00 G 30 J 20 H i0 I 5 -ichlcroethyla-e aTO_r (g):

.DTD:

llati dielent. omst. of in3[g, fill. (i Mz):

.DTD:

750 8 950 750 750 750 7 7 750 7 7 7 750 2000 2000 2000 i000 1500 500 4000 2500 200 i000 i00 700 i000 9.2 11.5 12.8 8.0 8.6 8.1 14.6 7.2 6.9 15.0 8.0 9.5 i0.0 Dissip.fact..009.010.011.009.010.010.012.011.010.015.004.005.003 (INI, 23 C) sola in hat resist. 120< 120< 120< 120< 120< 120< 120< 120< 120< 90< 120< 120< (ss.) SoI' ('15) (11<CK (I< CK (I< (I< (1< CK (I< CK CK (I< CK resist.

.DTD:

Ibn. --,q).]s.

.DTD:

coeff.xy-dir. 45 (n/ c) 50 45 45 45 50 50 50 15 15 15 TART,F. 3 - II ratio (g): IO Erples 24 25 26 27 28 29 30 31 32 33 34 35 40 40 40 40 40 40 40 40 40 40 36 37 38 i00 Crrsl 'k lLer Crcssl'k t.tt.'Lt tJ.+ 40 40 40 40 40 40 40 40 40 30 120 120 120 120 120 120 120 120]20 120 120 120 40 Ini 6 6 6 6 6 6 6 6 4 4 4 4 4 4 2 ILug. fill. DI30 EL50 FI50 Jl00 M250 N200 0200 P200 [L30 R400 $400 T400 U400 L 50 D150 ethylene 830 800 800 800 800 800 800 800 800 800 800 800 800 800 750 dtu.-nt (g):

.DTD:

B] atiua dJ]t" abt. abt. bt. abt. abt. bt. abt. abt. abt. abt. abt. abt. abt. abt. abt.

.DTD:

cst. of 2ooo lOOO 5oo 30oo 2oo 7oo zooo 5oo 250 40 8o 9o 4o 1000 2ooo it-crg, fill.

.DTD:

(IH-'):

.DTD:

Solid state p+ie= Rel.diele=t. 8.5 9.0 9.1 7.0 10.7 9.5 10.2 10.5 10.5 10.0 11.0 11.5 9.5 9. 8 9.3 o:::rst. ('Hz) Dissip.fact..004.005.004.004.004.004.005.003.003.003.003.003.003.008.009 (iM-Iz, 23 C) ", < Sold'g heat 120< 120< 120< 120< 120< 120< 120< 120< 120< 120< 120< 120< 120< 120< 120 resist. (See) Solv. resist. (11< CK CK CK CK CK a< (11< CK ilK' (11< (11< CK CK f. xyiir. 17 16 16 19 15 15 15 15 15 14 14 14 14 14 35 (p,, o c) emp.D-ales 3 4 i00 4O 4O 120 2 6 75O 8OO 2.7 3.0 003.003 i00 20 I LO LO I In the above Table 3, ii is styrene-butadien copolymer, 12 is triallyl isocyanurate, "13 is 2,5-dimethyl-2,5-di(tert-butyl-peroxy)hexyne-3; in 14, D is BaTiO3 ceramic, E is PbZrO3 ceramic, F is PbTiO3 ceramic, G is SrTiO3 ceramic, H is CaTiO3 ceramic, I is MgTiO3 ceramic, J is BaZrO3 ceramic, K is K20-PbOSiO2 glass, L is a sintered member of PbTiO3 and pbZrO3, M is TiO2 ceramix, N is Bi4Ti3Ol2 ceramic, 0 is a powder obtained by crushing a fired member of a mixture of TiO2 1000g, BaTiO3 200g and ZrO2 10g, P is a powder obtained by crushing a fired member of a mixture of TiO2 700g, BiTiO3 300g and SrTiO3 300g, Q is SrTiO3 ceramic, R is ZrTiO4 ceramic, S is BaNd2Ti5Ol4 ceramic, T is Ba0.5Pb0.5Nd2Ti5Ol4 ceramic, and U is Ba(Znl/3Nb2/3)O3 ceramic; and "15 is appearance observed after being dipped for five minutes within boiled trichloroethylene.

.DTD:

As will be clear from the above Table 3, the laminates in which the set product of the PPO resin composition according to the Examples ii through 38 of the present invention can be varied in the relative dielectric constant depending on the added amount of the inorganic filler, and can be made excellent in the heat resistance, chemical resistance and physical strength.

.DTD:

The inorganic fillers employed in the foregoing Examples 1 through 38 were such fired materials as shown in following Table 4:

.DTD:

TABLE 4 - I par4nle of i,']cU-'.fi 1]. Etmatiples (wt.%): 1 2 lm 12 12 3 4 5 6 7 8 9 I0 ii 12 13 14 15 16 17 18 19 20 21 22 23 12 12 12 6 6 6 6 6 12 12 12 17 17 17 17 17 17 17 17 17 17 atrme i, m 68 68 68 68 68 ii Ii ii Ii ii 68 68 68 63 63 63 63 63 63 63 63 63 63 belm4 2.5um ebue 2.5m 12 12 12 12 12 1"7, 17 17 17 17 12 12 12 12 12 12 12 12 12 12 12 12 12 be]_o 4.0 m atrve 4.0m 5 5 5 5 5 42 42 42 42 42 5 5 5 5 5 5 5 5 5 5 5 5 5 bel, 5.5,m 5.5 urn 3 3 3 3 3 23 23 23 23 23 3 3 3 3 3 3 3 3 3 3 3 3 3 be]fw 7.0 m 7.0 m 0 0 0 0 5 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 Ave partide size (m): 1.8 1.8 1.8 1.8 1.8 5.5 5.5 5.5 5.5 5.5 1.9 1.9 1.9 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Firing cmSif ors:

.DTD:

Tsp. ( C) Tism(hrs.) 1450 1450 1450 1350 1350 1450 1450 1450 1450 1450 1350 1350 1350 1000 I000 1000 1350 1350 1350 1350 1350 1350 1350 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 W W W X X W W W W W W W W W," W X X Y Z W W Z ! bo n I TABLE 4 - II .DTD:

Porticle iTe diU cn of ir. fill L=amples (wt.%): 24 25 26 27 28 29 30 31 32 33 34 135 36 37 38 1 N m 12 17 17 17 17 17 17 17 17 17 17 17 17 17 12 68 63 63 63 63 63 63 63 63 63 63 63 63 63 68 2 12 m 12 12 12 12 n 2 12 12 12 12 12 n 5 5 5 5 5 5 5 5 5 5 5 5.5pm h-icw 7.Om 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 6 7.0pm 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Au'-agg_ _ part. site_ Cvm):

.DTD:

1.9 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.9 Firing ccrriiticr:

.DTD:

Tsp. ( C) 1350 i000 I000 1350 1350 1350 1350 1350 1350 1350 1350 1350 1350 1350 1350 Tim(hrs.) 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Type: W W W W W W Z Z W W W W W Z W I to O' I i0 In the above Table 4, W denotes a fired member, X denotes a mixture of the fired members, y denotes a solid solution (glass), and Z is a fired member of a mix%ure of the fired members. EX{PLE 39:

.DTD:

In a reactor of 2 liters capacity and having a vacuum means, 70g of PPO, 20g of styrene-butadien copolymer (SOLPREN T460 by ASAHI KASEI), 10g of polybutadiene (by a Japanese manufacturer NIPPON SODA K.K.), 10g of triallyl isocyanurate (TAIC by NIPPON KASEI) and 2g of 2,5-dimethyl-2,5-di(tert-butyl-peroxy)hexyne-3 (PERHEXYNE 25B by NIPPON YUSHI) were placed, 750g of trychloroethylene (TRICHLEN by TOA GOSEI) was added thereto, and they were sufficiently stirred until a homogeneous solution was obtained. Thereafter, 38g of glass flakes (by NIPPON GLASS FIBER K.K.) of an average thickness 2 to 3 u m, aspect ratio 300 to 500 and mesh below 150 were added and sufficiently stirred to have them uniformly dispersed within the solution. A defoaming was performed, and thereby obtained PPO resin composition was applied by means of a coater onto a PET film to be a layer of a thickness of 500 m. After an air drying, the applied layer was further dried at 50 C for about i0 minutes, thus produced film was released from the PET film, the film was further dried at 120 C for 30 minutes to have trichloroethylene removed completely, and a sheet of a thickness of about 100 m of the PPO resin composition was thus obtained. Ten of the thus obtained sheets were stacked and mold-formed to be 300 x 300 mm, a copper foil of 35 u m thick was joined to each of top and bottom surfaces of the mold- formed stack, which were heat-pressed at 240 C under 50 kg/cm2 for 30 minutes to have the sheets completely set, and a laminate was obtained.

.DTD:

EXAMPLES 40 to 45:

.DTD:

Different laminates were obtained substantially through the same steps as in Example 39, except for such changes in the composition ratio as in following Table 5. COMPARATIVE EXAMPLES 5 & 6:

.DTD:

Further laminates were obúained substantially through the same steps as in Example 39, except for omission of the inorganic filler and such changes in the composition ratio as in the Table 5.

.DTD:

In the following Table 5, the solid state properties of the respective laminates according to Examples 29 through 45 as well as those of Comparative Examples 5 and 6 are also shown.

.DTD:

TABLE 5 po Patio Cg):

.DTD:

EaTps 39 40 41 42 43 44 45 PPO 60 70 60 60 60 Crcs. pol 1('21) 20 20 20 20 20 20 20 (os. pol!a 2(22) i0 10 i0 i0 10 i0 10 Cs.,,u (23) i0 i0 i0 i0 i0 i0 i0 Init_iatcr(4) 2 2 2 2 2 2 2 Cp. Denpl 5 6 2O i0 i0 i0 i0 1 - i0 :r_na. f]]. (25) cli_ele:.

.DTD:

o::nst, c fu.(m:

.DTD:

52 35 4 6 6 6 6 6 6 6 S/id. state prqo..-.

.DTD:

2.9 3.0 2.8 3:.0 2.9 4.2 4.6 rst. () mp.ft.()......5.

.DTD:

2.6 2.6 003.002 Solci ht 80 80 80 >120 >120 <. (s.) CUT CUT CK eoa. f.

xy/r.(qmV C). 50 45 50 50 55 20 mge (nm) 20 17 22 17 20 4 3 4O 5O In the above Table 5: "21 denotes styrene-butadiene copolymer; 22 denotes polybutadiene; 23 denotes triallyl isocyanurate; 24 denotes 2,5-dimethyl-2,5-di (tert-butyl-peroxy)hexyne-3; in 25, Vl is glass flakes of average thickness 2 to 3 m, aspect ratio 300 to 500 and mesh less than 150, and V2 is mica of average thickness 5 to 15 m, aspect ratio 50 to i00 and mesh less than 150 ( a commonmica by TOPY KOGYO); "26 is appearance observed after 5 minutes dipping n boiling trichloroethylene; and 27 is appearance observed after 5 minutes dipping in alkali solution at 40 C. The warpage was determined by an average distance measured for respective corners of the laminate from a reference plane, the laminate mold-formed in 300 x 300 mm being subjected to whole removal of the copper foil from one surface by means of an etching and placed on the reference plane with the foil-removed face disposed to be top.

.DTD:

As will be clear from Table 5, it is found that the laminates obtained through Examples 39 to 45 employing the set products of the PPO resin composition according to the present invention show, in addition to that the relative dielectric constant can be optimumly varied while definitely improved in the heat resistance, chemical resistance and physical strength, remarkable restraint of the warpage occurrence by means of the glass flake or mica employed as the inorganic filler.

.DTD:

The relative dielectric constant of the inorganic fillers employed in the foregoing Examples 1 through 45 has been obtained in such that each inorganic filler employed in each Example was added by the same amount as in each Example to the composition of Comparative Example 3, a copper clad laminate was thereby obtained, the relative dielectric constant of this copper clad laminate was measured on the base of Japanese Industrial Standard (JIS) C 6481, the volume fraction as well as the relative dielectric constant of another component than the inorganic filler of the composition were obtained, and the relative dielectric constant of the inorganic filler was then obtained with the measured values of the copper clad laminate and of another component on the basis of a formula log Cy =.z Vi-log Cyl1 :where ey is the: relative dielectric constant of the copper clad laminate, Vi is the volume fraction of a component i, and Eyl is the relative- dielectric constant of the component i.

.CLME:

Claims

CLAIMS:

.CLME:

i, A polyphenylene Oxide resin composition, comprising from i0 to 95 parts by weight of polyphenylene oxide, from 1 to 90 parts by weight of at least one of crosslinking polymer, crosslinking monomer and mixtures of said crosslinking polymer and monomer, an initiator, and from 1 to 200 parts by weight of an inorganic filler of a high relative dielectric constant to be more than i0.

.CLME:
2. A composition of claim i, wherein said inorganic filler is selected from the group consisting of titanium dioxide ceramics, barium titanate ceramics, lead titanate ceramics, strontium titanate ceramics, calcium titanate ceramics, bismuth titanate ceramics, magnesium titanate ceramics, lead zirconate ceramics, and mixture thereof.

.CLME:
3. A composition of claim 2, wherein at least two of said ceramics are selected.

.CLME:
4. A composition of claim 3, wherein said at least two selected ceramics are mixed and sintered.

.CLME:

A composition of claim i, wherein said crosslinking polymer is selected and present in an amount of from
5 to 50 parts by weight, and said inorganic filler which is flaky is present in an amount of from 1 to 80 parts by weight.

.CLME:
6. A composition of claim I, wherein said crosslinking monomer is selected and present in an amount of from 1 to 20 parts by weight, and said inorganic filler which is flaky is present in an amount of from 1 to 80 parts by weight.

.CLME:
7. A composition of claim I, wherein said crosslinking polymer is present in an amount of from 5 to 50 parts by weight, said crosslinking monomer is present in an amount of from 1 to 20 parts by weight, and said inorganic filler which is flaky is present in an amount of from 1 to 80 parts by weight.

.CLME:
8. A composition of claim i, wherein said composition is formed in a sheet
9. A method of preparing a polyphenylene oxide resin composition, comprising the steps of preparing an inorganic filler of a high relative dielectric constant to be more than
i0 by mixing at least two raw materials selected from the group consisting of titanium dioxide, barium titanate, lead titanate, strontium titanate, calcium titanate, bismuch titanate, magnesium titanate and lead zirconate, firing and crushing the materials into said inorganic filler; and mixing from 1 to 200 parts by weight of said inorganic filler with from i0 to 95 parts by weight of polyphenylene oxide, from 1 to 90 parts by weight of at least one of crosslinking polymer, crosslinking monomer and mixtures of said crosslinking polymer and monomer, and an initiator.

.CLME:

i0. A method of forming a polyphenylene oxide film using said polyphenylene oxide resin composition according to claim 9, comprising the steps of dispersing said composition in a solvent, and forming said dispersed composition into a film.

.CLME:
Ii. A method of preparing a prepreg using said polyphenylene oxide resin composition according to claim 9, comprising the steps of dispersing said composition in a solvent, impregnating a member with said dispersed composition, and removing said solvent from said impregnated base material.

.CLME:
12 A method of preparing a set resin product of said film according to claim i0, wherein one or a stack of at least two of said film according to claim i0 is heated under a pressure to set.

.CLME:
13. A method of preparing a set resin product of said prepreg according to claim ii, wherein one or a stack of at least two of said prepreg according to claim ii is heated under a pressure to set
14. A method of preparing a set resin produc according to claim 12, wherein a copper foil is adhered to at least a surface of Said set film or said set stack of said films.

.CLME:
15. A method of preparing a set resin product according to claim 13, wherein a copper foil is adhered to at least a surface of said set prepreg.

.CLME:
16:. A polyphenylene oxide resin composition substantially as described herein with reference to the examples.

.CLME:
17. A method of preparing a polyphenylene oxide resin composition substantially as described herein with reference to the examples.

.CLME:

Published 1988 at The Patent Office. State House, 66ql High Holborn, London WC1R 4TP. Further copies may be obtained from The Paten Office.

.CLME:

Sales Branch, St Mary Cray, Orpington, Kent BRS 3RD. Printed by Mu/tlplex techniques lUi St Mary Cray, Kent. Con. 1187.

.CLME: