WO1991002363A1 - Compositions dielectriques poreuses - Google Patents

Compositions dielectriques poreuses Download PDF

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Publication number
WO1991002363A1
WO1991002363A1 PCT/US1990/004383 US9004383W WO9102363A1 WO 1991002363 A1 WO1991002363 A1 WO 1991002363A1 US 9004383 W US9004383 W US 9004383W WO 9102363 A1 WO9102363 A1 WO 9102363A1
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Prior art keywords
weight
composition
glass
dielectric
ceramic
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Application number
PCT/US1990/004383
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English (en)
Inventor
Aziz S. Shaikh
Original Assignee
Ferro Corporation
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Publication date
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Publication of WO1991002363A1 publication Critical patent/WO1991002363A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/08—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances quartz; glass; glass wool; slag wool; vitreous enamels
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0054—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing PbO, SnO2, B2O3
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C11/00—Multi-cellular glass ; Porous or hollow glass or glass particles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C4/00—Compositions for glass with special properties
    • C03C4/16—Compositions for glass with special properties for dielectric glass
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0306—Inorganic insulating substrates, e.g. ceramic, glass

Definitions

  • This invention relates to porous dielectric compositions, and to multilayered circuits, thick film circuits and other electronic components using these compositions.
  • the invention also relates to dielectric pastes and dielectric tapes for providing such porous dielectric compositions, and to a method of making such porous dielectric compositions.
  • Multilayer thick film circuits have been used for many years to increase circuit functionality per unit of area.
  • the dielectrics used in these circuits are comprised of finely divided particles of dielectric solids, dispersed in an inert organic medium, the dielec ⁇ tric solids being inorganic oxides or glasses.
  • Recent advances in circuit technology include the requirements of higher circuit densities and higher propagation speeds. Dielectric materials having low dielectric constants that are stable at high temperatures and high humidities and that have good mechanical properties are required for such uses.
  • Vacuum has the lowest dielectric constant, which is 1.0.
  • Polymeric dielectric materials typically have dielectric constants in the range of about 2.6 to about 3.8. Some of the problems associated with these polymeric materials include their inability to withstand high temperatures, their degradation under extended exposure to temperatures in excess of about 200°C, poor thermal conductivity and poor resistance to humidity. Glass-ceramic materials are more stable than polymeric materials at high temperature and in humid atmosphere, and have better mechanical properties for most dielec ⁇ tric applications than such polymeric materials. How ⁇ ever, glass-ceramic materials have higher dielectric constants than polymeric materials, typically in the range of about 7-12, and have thus far not been found to be acceptable for use as dielectrics in thick film circuits and the like.
  • This invention provides for a porous dielectric composition
  • a porous dielectric composition comprising at least one crystallized glass, at least one non-crystallized glass, and at least one Group IIA metal silicate, the porosity of said compo ⁇ sition ranging from about 2% to about 50% by volume open space, the average diameter of the pore spaces in said composition ranging from about 1 to about 30 micromet ⁇ ers.
  • the invention also provides for dielectric pastes and dielectric tapes for providing these dielectric compositions.
  • the invention also provides for a process for making these dielectric compositions. These dielec ⁇ tric compositions are useful in making multilayered circuits, thick film circuits and other electronic com ⁇ ponents.
  • Fig. 1 is a photomicrograph of a cross-section of the composite structure made in accordance with Exam ⁇ ple 1 using a scanning electron microscope, the voltage being 15 KV and the magnification factor being 980X.
  • the bright dense layers at the top and bottom are gold conductor layers, and the dark porous portion between the conductor layers is the dielectric material.
  • Fig. 2 is a photomicrograph of a cross-section of the composite structure made in accordance with Exam ⁇ ple 2 using a scanning electron microscope, the voltage being 15 KV and the magnification factor being 830X.
  • the bright dense layers at the top and bottom are gold conductor layers, and the dark porous portion between the conductor layers is the dielectric material.
  • Fig. 3 is a photomicrograph of a cross-section of the composite structure made in accordance with Example 3 using a scanning electron microscope, the voltage being 15 KV and the magnification factor being 560X.
  • the bright dense layers at the top and bottom are gold conductor layers, and the dark porous portion between the conductor layers is the dielectric material.
  • Fig. 4 is a photomicrograph of a cross-section of the composite structure made in accordance with Example 4 using a scanning electron microscope, the voltage being 15 KV, the magnification factor being 870X.
  • the bright dense layers at the top and bottom are gold conductor layers, and the dark porous portion between the conductor layers is the dielectric material.
  • inventive dielectric compositions are com ⁇ prised of at least one crystallized glass (A), at least one non-crystallized glass (B), and at least one Group IIA metal silicate.
  • Glass (A) preferably has a glass transition temperature (Tg) in the range of about 600°C to about 650°C, more preferably about 610°C to about 630°C.
  • the dilatometric softening point (DSP) is preferably in the range of about 620°C to about 660°C, more preferably about 630°C to about 650°C.
  • the coefficient of thermal expansion (CTE) is preferably about 70 to about 114 x 10 ⁇ 7 /°C between room temperature and 300°C.
  • the density of glass (A) is preferably from about 2.4 to about 2.8 gms/cc, more preferably about 2.5 to about 2.7 gms/cc.
  • Glass (A) has the following composition:
  • Glass (B) preferably has a Tg in the range of about 450°C to about 520°C, more preferably about 460°C to about 500°C.
  • the DSP is preferably in the range of about 550°C to about 610°C, more preferably about 560°C to about 600°C.
  • the CTE is preferably about 28 to about 40 x 10 /°C between room temperature and 300°C.
  • the density of glass (B) is preferably from about 2 to about 2.4 gms/cc, more preferably about 2.1 to about 2.3 gms/- cc. Glass (B) has the following composition:
  • the Group IIA metal silicate is glass or ceramic (C).
  • Glass or ceramic (C) preferably has a Tg in the range of about 590°C to about 650°C, more preferably about 610°C to about 630°C.
  • the DSP is preferably in the range of about 650°C to about 690°C, more preferably about 660°C to about 680°C.
  • the CTE is preferably about 50 to about 60 x 10 ⁇ 7 /°C at room temperature to 300°C.
  • the den ⁇ sity of glass or ceramic (C) is preferably from about 2.9 to about 3.3 gms/cc, more preferably about 3.0 to about 3.2 gms/cc.
  • Glass or ceramic (C) has the follow ⁇ ing composition:
  • the Group IIA metal silicate is glass or ceramic (D) .
  • An example of glass or ceramic (D) is cordierite.
  • Glass or ceramic (D) preferably has a Tg in the range of about 740°C to about 820°C, more preferably about 750°C to about 790°C.
  • the DSP is preferably in the range of about 770°C to about 950°C, more preferably about 820°C to about 880°C.
  • the CTE is preferably about 10 to about 40 x 10 ⁇ 7 /°C at room temperature to 300°C.
  • the den ⁇ sity of glass or ceramic (D) is preferably from about 2.3 to about 2.9 gms/cc, more preferably about 2.4 to about 2.8 gms/cc.
  • Glass or ceramic (D) has the following composition:
  • the Group IIA metal silicate is comprised of at least two Group IIA metal silicates, one having the composi ⁇ tion of glass or ceramic (C) and the other having the composition of glass or ceramic (D) .
  • the inven ⁇ tive dielectric compositions can be comprised of glass or ceramics (A) + (B) + (C); (A) + (B) + (D); or (A) + (B) + (C) + (D).
  • Each of the above glass or ceramic compositions (A)-(D) can be prepared in any conventional manner. For example, a mixture of the appropriate ingredients can be placed in a platinum crucible and melted (e.g., 1450- 1550°C), the resulting glass composition is then poured onto cold steel rolls to form thin flakes suitable for milling. These flakes are then milled to a suitable particle size distribution (e.g., about 0.5 to about 20 micrometers) .
  • a suitable particle size distribution e.g., about 0.5 to about 20 micrometers
  • the inventive dielectric compositions prefer ⁇ ably contain from about 15% to about 80% by weight, more preferably about 20% to about 50% by weight of glass (A); about 15% to about 80% by weight, more preferably about 40% to about 70% by weight of glass (B); up to about 45% by weight, preferably about 5% to about 30% by weight of glass or ceramic (C); and up to about 40% by weight, preferably about 5% to about 25% by weight of glass or ceramic (D) .
  • each of components (C) and (D) is optional, at least one of these components must be present in the inventive dielec ⁇ tric compositions; said component preferably being pre ⁇ sent at a concentration level of at least about 3% by weight, more preferably at least about 5% by weight, more preferably at least about 8% by weight.
  • the total concentration of components (C) and (D) in the inventive dielectric compositions is preferably up to about 45% by weight, more preferably up to about 40% by weight, more preferably up to about 35% by weight, more preferably up to about 28% by weight.
  • the inventive dielectric compo ⁇ sitions can also contain up to about 5% by weight, more preferably up to about 3% by weight, more preferably up to about 1% by weight of (E), at least one crystallizing agent.
  • An example of such a crystallizing agent is CaB ⁇ 4.
  • the inventive dielectric compositions can also contain up to about 5% by weight, more preferably up to about 3% by weight, more preferably up to about 1% by weight of (F), at least one colorant.
  • An example of such a colorant is Cr 2 ⁇ 3.
  • Components (A)-(F) are milled together in the presence of an alcohol using conventional ball-milling techniques to provide a mixture of particulate solids having an average diameter in the range of about 2 to about 10 micrometers, more preferably about 3 to about 7 micrometers.
  • the resulting product is a homogeneous mix ⁇ ture of solids and alcohol.
  • the solids are dried, and then can be dispersed in a suitable vehicle or binder to provide a dielectric paste or dielectric tape.
  • the alcohol used in milling the components (A)- (F) is preferalby a monohydric, saturated or unsaturated aliphatic alcohol of about 1 to about 6 carbon atoms, more preferably about 2 to about 5 carbon atoms.
  • Exam ⁇ ples include methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol, n-hexyl alcohol, isopropyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isopentyl alcohol, amyl alcohol, tert-pentyl alcohol, cyclopentanol, cyclohex- anol, allyl alcohol, crotyl alcohol, methyl vinyl car- binol, etc.
  • Isopropyl alcohol is preferred.
  • the invention provides for dielectric pastes comprising a binder or vehicle with glass or ceramic particulate solids (A), (B) and (C) and/or (D), and optionally components (E) and/or (F), dispersed in said binder or vehicle.
  • the binder or vehicle can be water or water-based or it can be organic; it is preferably organic.
  • the binder or vehicle is provided in an amount sufficient to disperse the solids in the binder or vehicle.
  • the solid components are preferably present in the range of about 60% to about 80% by weight, more preferably about 60% to about 70% by weight of the inven ⁇ tive dielectric paste compositions, and the binder or vehicle is preferably present in the range of about 20% to about 40% by weight, more preferably about 30% to about 40% by weight of such dielectric paste composi ⁇ tion.
  • the organic binder or vehicle is preferably an organic resin dissolved in a suitable solvent. Any essentially inert binder or vehicle can be used in the practice of the present invention, including various organic liquids, with or without thickening and/or stabilizing agents and/or other common additives.
  • Exem ⁇ plary of the organic liquids which can be used are the aliphatic alcohols; esters of such alcohols, for exam ⁇ ple, the acetates and propionates; terpenes such as pine oil, terpineol and the like; solutions of resins such as the polymethacrylates of lower alcohols, or solutions of ethyl cellulose, in solvents such as pine oil, the mono- butyl ether of ethylene glycol monoacetate, and car- bitol.
  • the binder can contain volatile liquids to pro ⁇ mote fast setting after application to the substrate.
  • the vehicle or binder contains from about 65% to about 90% by weight of at least one solvent, about 4% to about 10% by weight of at least one resin, up to about 30% by weight of at least one plasticizer, up to about 10% by weight of at least one thixotropic agent, and up to about 10% by weight of at least one surfactant or dispersant.
  • the vehicle or binder contains from about 0.1% to about 20% by weight resin, more preferably about 0.1% to about 10% by weight resin, and about 80% to about 99.9% by weight, more preferably about 90% to about 99.9% by weight, solvent or mixture of solvents.
  • the resin can be ethyl cellulose or an acrylate resin (e.g., methyl methacryl- ate).
  • the solvent can be terpineol, 2,4,4-trimethyl- 1 ,3-pentanediol monoisobutylrate, N-methyl-2-pyrrolidone or mixtures thereof.
  • the vehicle or binder can include thixotropic agents, preferably at concentrations of up to about 10% by weight; and conventional dispersants, preferably at concentrations of up to about 10% by weight.
  • the inventive thick film dielectric paste compo ⁇ sition can be applied to a substrate using techniques well-known to those skilled in the art.
  • An example of such a technique is silk screening wherein the paste is forced through a fine mesh stainless steel screen in a desired pattern. Typically the size of such a screen varies from about 200 to about 325 mesh.
  • Other examples include spraying, dipping, spinning, brushing and appli ⁇ cation using a doctor blade.
  • the invention also relates to dielectric tapes or "green tapes" comprising a flexible substrate and the inventive dielectric composition adhered to the flexible substrate.
  • These tapes are made by casting a dispersion of the inventive dielectric composition in a binder or vehicle onto a flexible substrate, such as a steel belt or polymeric film, and then heating the cast layer to remove the volatile solvent.
  • the binder or vehicle can be the same as described above for use in making dielec ⁇ tric pastes.
  • the solvent preferably has a boiling point below about 150°C and the heating step used to remove the sol ⁇ vent is conducted at a sufficient temperature to vapor ⁇ ize the solvent.
  • solvents examples include acetone, xylene, methanol, ethanol, isopropanol, methyl ethyl ketone, 1 ,1 ,1-trichlorethane, tetrachloroethylene, amyl acetate, 2,2,4-triethyl pentanediol-1 ,3-monoiso- butyrate, toluene, methylene chloride and fluorocar- bons. It will be recognized that individual components of the solvent may not be complete solvents for the binder polymer. Yet, when blended with other solvent components, they function as solvents.
  • the dielectric tape can be used as a dielectric or insulating material for multilayer electronic cir ⁇ cuits.
  • a roll of dielectric tape is blanked with regis ⁇ tration holes in each corner to a size somewhat larger than the actual dimensions of the circuit.
  • via holes are formed in the dielectric tape. This is typically done by mechanical punching. However, a sharply focused laser can be used to volatilize the dielectric tape. Typical via hole sizes range from about 0.006 to about 0.25 inch.
  • the interconnections between layers are formed by filling the via holes with a thick film con ⁇ ductive ink. This ink is usually applied by standard screen printing techniques. Each layer of circuitry is completed by screen printing conductor tracks.
  • resistor inks or high dielectric capacitor inks can be printed on each layer to form resistive or capacitive circuit elements.
  • high dielectric constant green tapes similar to those used in the multilayer capacitor industry can be incorporated as part of the multilayer circuitry.
  • the individual layers are stacked and laminated.
  • a confined pressing die is used to insure precise align ⁇ ment between layers.
  • the laminates are trimmed with a hot stage cutter. Firing can be carried out in a standard thick film conveyor belt furnace.
  • the inventive dielectric pastes and dielectric tapes are preferably fired in an oxidizing atmosphere at a peak temperature preferably in the range of about 750°C to about 1150°C, more preferably about 800°C to about 950°C, more preferably about 825°C to about 875°C.
  • firing at the peak temperature is maintained for about one minute to about one hour, more preferably about 2 to about 45 minutes, more preferably about 5 to about 40 minutes, more preferably about 5 to about 20 minutes, more preferably about 8 to about 15 minutes.
  • the heat-up rate is preferably about 20°C to about 90°C per minute, more preferably about 30°C to about 80°C per minute.
  • the cool-down rate is preferably about 20°C to about 90°C per minute, more preferably about 30°C to about 80°C per minute.
  • the oxidizing atmosphere prefer ⁇ ably comprises about 10% to about 100% by volume oxygen, more preferably about 10% to about 50% by volume oxygen, more preferably about 15% to about 25% by volume oxygen; the balence being an inert gas such as nitrogen, helium or argon. Air is a preferred oxidizing atmosphere.
  • the pressure in the firing zone is preferably in the range of about 0.1 to about 5 atmospheres, more preferably about 0.5 to about 2 atmospheres, and advantageously the pressure is atmospheric pressure.
  • firing is used herein to mean heating to a temperature and for a time sufficient to volatilize (burnout) all of the water or organic material in the dielectric paste or dielec ⁇ tric tape and to sinter the glass or ceramic materials (A), (B) and (C) and/or (D) .
  • the fired inventive dielectric composition preferably has a dielectric constant (k) of up to about 5, more preferably about 2 to about 5, more preferably about 2 to about 4.5; an insulation resistance (IR) of preferably greater than about 10 11 ohms, more prefer- ably greater than about 10 12 ohms and typically in the range of about 101 1 to about 10 "°- ohms; a dissipa ⁇ tion factor (Tan delta) of preferably about 0.02% to about 0.6%, more preferably about 0.05% to about 0.5%; and a breakdown voltage (BDV) in the range of about 200 to about 2200 volts per mil.
  • Dielectric layers applied to substrates and fired in accordance with the invention preferably have thicknesses in the range of about 40 to about 100 micrometers, more preferably about 45 to about 70 micrometers.
  • the fired inventive dielectric composition preferably has a porosity in the range of about 2% to about 50% by volume open space, more preferably about 10% to about 50%, more preferably about 20% to about 50%, more preferably about 25% to about 45% by volume open space.
  • the average diameter of the pore spaces preferably ranges from about 1 to about 30 micrometers, more preferably about 5 to about 30 micrometers.
  • Poros ⁇ ity is measured using a photomicrograph of a cross-sec ⁇ tion taken at random of the fired inventive dielectric composition at a magnification factor in the range of 500X to 1000X.
  • a clear planar square grid is used that is 4 cm in length on a side, and contains five horizon ⁇ tal parallel lines each spaced 1 cm apart and five ver ⁇ tical parallel lines each spaced 1 cm apart, the hori ⁇ zontal and vertical lines having a total of 25 equally spaced points of intersection.
  • the grid is randomly placed over the photomicrograph and the number of grid points overlying pores is counted.
  • a grid point landing on a line dividing a pore and a dense mass is counted as a one-half grid point.
  • the procedure is performed three times for each photomicrograph, the grid being placed in a different random location each time, and the average number of grid points is determined for the three mea- surements.
  • the porosity is calculated by dividing the average number of grid points overlying pores by the total number of grid points (25).
  • the average diameter of the pore spaces is calculated from measurements of the pore diameters taken from these photomicrographs.
  • the glass or ceramic powders (A)-(C) of the invention are milled using a 1450 ml alum ⁇ ina lined mill.
  • the solids grinding medium consists of sintered alumina cylinders with diameters of 0.5-inch and lengths of 0.5 inch. 254 ml of isopropyl alcohol or water is used as the liquid grinding medium.
  • the glass or ceramic material charge to the mill is 8.5% by volume of the mill volume.
  • Each glass or ceramic material is milled at a rate of 55 rpm until the desired particle size is achieved.
  • the glass or ceramic powder-liquid medium slurries are removed from the mill and dried at 60°C.
  • the resulting glass or ceramic powders have the compositions indicated in Table I.
  • Glass materials A-1 , A-2 and A-3 are milled as fol ⁇ lows: charge is 332 grams; milling time is 24 hours; liquid medium is water; average particle size of the final product is about 4.9 micrometers.
  • Glass material B-1 is milled as follows: charge is 271 grams; milling time is 46 hours; liquid medium is isopropyl alcohol; average particle size of the final product is 3.1 micrometers.
  • Glass or ceramic material C-1 is milled as follows: charge is 382 grams; milling time is 52 hours; liquid medium is isopropyl alcohol; average particle size of the final product is 3.3 micrometers.
  • glass powders A-1, A-2 and A-3 correspond to glass (A) of the invention.
  • Glass powder B-1 corresponds to glass (B) of the invention, and glass or ceramic powder C-1 corresponds to glass or ceramic (C) of the invention.
  • cordierite J.C.P.D.S. X-Ray card 12-303
  • the charge is 1000 grams.
  • Milling time is 24 hours.
  • the liquid medium is a 1:1 weight ratio mixture of isopropyl alcohol and water.
  • the milling time is 24 hours and the average particle size is 1.2 micrometers.
  • the formulations identified in Table II are prepared using the glass or ceramic powders identified in Table I, and the milled cordierite referred to above.
  • the glass or ceramic powders A-1, A-2, A-3, B-1 and C-1 along with cordierite, CaB 2 04 and Cr0 2 , in the proportions indicated in Table II, are loaded in a 300 ml alumina lined mill containing 70 ml of isopropyl alcohol and 150 grams of alumina cylinders having diameters of 0.5 inch and lengths of 0.5 inch.
  • the slurries are milled for 30 minutes, transferred to stainless steel pans, and dried in a convection oven at 60°C overnight.
  • the resulting dry solids mixtures are blended with an organic vehicle or binder to form a paste.
  • the organic vehicle or binder is made from the following ingredients:
  • Texanol product of Eastman Kodak Chemicals identified as 2,4,4- trimethyl-1 ,3-pentanediol mono- isobutylrate
  • Alpha-Terpineol product of Hercules identified as alpha-4-trimethyl- 3-cyclohexane-1-methanol 7.80
  • Ethyl Cellulose N-300 product of Hercules identified as an ethyl cellulose resin 0.49
  • Thixatrol ST product of NL Indus ⁇ tries identified as a low mole ⁇ cular weight amide useful as a thixotropic agent
  • Solsperse 3000 product of ICI Amer ⁇ ica identified as a dispersant
  • the mixtures of dry powder and organic vehicle or binder are placed in containers.
  • the containers are sealed and placed in paint shakers wherein they are shaken for three minutes.
  • the containers are opened and the contents are transferred to a dispersion mill.
  • the mixtures are passed through the mill four times, the resulting products being in the form of pastes.
  • the pastes contain 32-38% by weight organic vehicle or binder and 68-62% by weight solids.
  • Composite structures for each example are prepared as follows.
  • a gold conductor paste, Conductrox 3066 (a product of Ferro Corporation identified as a gold conductor paste) is printed on an alumina substrate using a 325 mesh Tyler Standard screen.
  • the thickness of the printed layer is 0.7 mil.
  • the printed layer is allowed to level for 5-10 minutes at room temperature, and is then dried at 100°C for seven minutes.
  • the dried printed layer is fired at 850°C in air; the temperature of the printed layer is increased from ambient to 850°C over a 10-minute period, maintained at 850°C for 10 minutes, then reduced to ambient over a 10-minute period.
  • a dielectric layer using the pastes described above and the formulations reported in Table II is then printed over the conductor layer using the same print ⁇ ing, levelling, drying and firing procedure used for the conductor layer.
  • Second and third dielectric layers using the same formulation as the first dielectric layer are then printed over the first and second dielectric layers, respectively, the same printing, levelling, drying and firing procedure used for the conductor layer being used.
  • a second conductor layer using the same conductor material as the first conductor layer is then printed over the third dielectric layer using the same printing, levelling, drying and firing procedure as with the first conductor layer.
  • the resulting composite structures have thicknesses of about 55 micrometers.
  • the dielectric constants (k) and the dissipa ⁇ tion factors (Tan delta) are measured using a Model 4192A Hewlett Packard bridge and are reported in Table II. These dielectric constants range from 2.21 to 4.72 indicating significantly lower values than those for most glass-ceramic materials which typically have dielectric constants in the range of about 7-12. These dielectric constants are comparable to those available with commercial polyimide dielectrics which typically exhibit dielectric constants of up to about 4.
  • the dielectric breakdown voltage is determined by increasing the voltage applied across the thickness of the sample until breakdown occurs.
  • a fluke Model 412B high voltage power supply is used.
  • Warpage is determined using the dielectric compositions of Examples 2, 6, 7, 23, 25 and 26, the results being reported in Table III.
  • a layer of the indicated dielectric compo ⁇ sition is printed on an alumina-based substrate (96% by weight alumina) and then fired using the procedure and firing conditions indicated above for the preparation of the composites reported in Table II.
  • a second dielec ⁇ tric layer is printed over the first dielectric layer and then fired in the same manner as the first dielec ⁇ tric layer.
  • a third dielectric layer is printed over the second dielectric layer and then fired in the same manner as the first dielectric layer.
  • the composite is then fired again using the same firing procedure and conditions as with the first dielectric layer.
  • the sequence is continued until composites with the number of layers indicated in Table III are obtained. Warpage is determined using a square test pattern and a drop-dial gauge. The readings at the corner and the center are determined and the average of
  • Photomicrographs of cross-sections of the com ⁇ posites made in accordance with Examples 1-4 are provided as Figs. 1-4, respectively. These photomi ⁇ crographs are used to determine porosity using the fol ⁇ lowing procedure.
  • a clear planar square grid is used that is 4 cm in length on a side, and contains five hori ⁇ zontal parallel lines each spaced 1 cm apart and five vertical parallel lines each spaced 1 cm apart, the hor ⁇ izontal and vertical lines having a total of 25 equally spaced points of intersection.
  • the grid is randomly placed over each photomicrograph and the number of grid points overlying pores is counted.
  • a grid point landing on a line dividing a pore and a dense mass is counted as a one-half grid point.
  • the procedure is performed three times for each photomicrograph, the grid being placed in a different random location each time, and the average number of grid points is determined for the three mea ⁇ surements.
  • the porosity is calculated by dividing the average number of grid points overlying pores by the total number of grid points (25).
  • the porosity of the dielectric materials of the composites made in accord ⁇ ance with Examples 1-4 are as follows:
  • an advantage of the present invention is that the inventive dielectric compositions have thermal expan ⁇ sion characteristics that match alumina sufficiently so that they can be used in conjunction with alumina or alumina-based substrates for making cofired multilayer circuits having alumina or alumina-based substrates.
  • the inventive dielectric compositions are compatible with noble metals so that silver, gold and palladium as well as copper conductors can be used.
  • these dielectric compositions can be fired using a typical thick film or dielectric tape firing profile.

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Abstract

Cette invention concerne une composition diélectrique poreuse comprenant au moins un verre cristallisé, au moins un verre non cristallisé et au moins un silicate de métal du groupe IIA, la porosité de ladite composition allant de 2 % environ jusqu'à 50 % environ en volume de l'espace ouvert, le diamètre moyen des espaces des pores de ladite composition allant de 1 à 30 micromètres environ. L'invention concerne également des pâtes diélectriques et des bandes diélectriques pour obtenir ces compositions diélectriques. L'invention concerne également un procédé de fabrication de ces compositions diélectriques. Ces compositions diélectriques sont utiles à la fabrication de circuits multicouches, de circuits à films épais et d'autres composants électroniques.
PCT/US1990/004383 1989-08-04 1990-08-03 Compositions dielectriques poreuses WO1991002363A1 (fr)

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US389,778 1989-08-04

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0552522A1 (fr) * 1988-10-14 1993-07-28 Ferro Corporation Vitrocéramiques à constante diélectrique faible, fritté à températures basses
US5258335A (en) * 1988-10-14 1993-11-02 Ferro Corporation Low dielectric, low temperature fired glass ceramics

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH471437A (de) * 1963-12-30 1969-04-15 Philips Nv Verfahren zur Herstellung eines glasartigen Dielektrikums
EP0163155A1 (fr) * 1984-06-01 1985-12-04 Narumi China Corporation Céramiques cuites à basse température
EP0219807A2 (fr) * 1985-10-25 1987-04-29 Narumi China Corporation Céramiques cuites à basse température
EP0234338A1 (fr) * 1986-02-13 1987-09-02 W.C. Heraeus GmbH Compositions diélectriques pour multicouches à couches épaisses pour cuisson sous air et azote
EP0253342A1 (fr) * 1986-07-15 1988-01-20 E.I. Du Pont De Nemours And Company Compositions diélectriques vitrocéramiques
EP0265340A2 (fr) * 1986-10-23 1988-04-27 Fujitsu Limited Panneau multi-couche en céramique pour circuit de cuivre
WO1990000966A1 (fr) * 1988-07-19 1990-02-08 Ferro Corporation Compositions dielectriques pour couches epaisses

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH471437A (de) * 1963-12-30 1969-04-15 Philips Nv Verfahren zur Herstellung eines glasartigen Dielektrikums
EP0163155A1 (fr) * 1984-06-01 1985-12-04 Narumi China Corporation Céramiques cuites à basse température
EP0219807A2 (fr) * 1985-10-25 1987-04-29 Narumi China Corporation Céramiques cuites à basse température
EP0234338A1 (fr) * 1986-02-13 1987-09-02 W.C. Heraeus GmbH Compositions diélectriques pour multicouches à couches épaisses pour cuisson sous air et azote
EP0253342A1 (fr) * 1986-07-15 1988-01-20 E.I. Du Pont De Nemours And Company Compositions diélectriques vitrocéramiques
EP0265340A2 (fr) * 1986-10-23 1988-04-27 Fujitsu Limited Panneau multi-couche en céramique pour circuit de cuivre
WO1990000966A1 (fr) * 1988-07-19 1990-02-08 Ferro Corporation Compositions dielectriques pour couches epaisses

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0552522A1 (fr) * 1988-10-14 1993-07-28 Ferro Corporation Vitrocéramiques à constante diélectrique faible, fritté à températures basses
US5258335A (en) * 1988-10-14 1993-11-02 Ferro Corporation Low dielectric, low temperature fired glass ceramics

Also Published As

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