WO1989001461A1 - Boitiers en metal/ceramique conjointement frittables et materiaux utilises pour leur fabrication - Google Patents

Boitiers en metal/ceramique conjointement frittables et materiaux utilises pour leur fabrication Download PDF

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Publication number
WO1989001461A1
WO1989001461A1 PCT/US1988/002788 US8802788W WO8901461A1 WO 1989001461 A1 WO1989001461 A1 WO 1989001461A1 US 8802788 W US8802788 W US 8802788W WO 8901461 A1 WO8901461 A1 WO 8901461A1
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WIPO (PCT)
Prior art keywords
oxide
package
glassy
glass
filler
Prior art date
Application number
PCT/US1988/002788
Other languages
English (en)
Inventor
Eric A. Barringer
Sheldon I. Lieberman
William C. Gruber
James D. Hodge
Ellen S. Tormey
Ran-Rong Lee
Brian W. Saxton
Richard Waack
Donald J. Kelley
Original Assignee
Ceramics Process Systems Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US07/085,078 external-priority patent/US4788046A/en
Priority claimed from US07/085,950 external-priority patent/US4861646A/en
Priority claimed from US07/085,077 external-priority patent/US5062891A/en
Application filed by Ceramics Process Systems Corporation filed Critical Ceramics Process Systems Corporation
Publication of WO1989001461A1 publication Critical patent/WO1989001461A1/fr

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Classifications

    • 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
    • C03C14/00—Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed in a glass matrix
    • C03C14/004—Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed in a glass matrix the non-glass component being in the form of particles or flakes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4803—Insulating or insulated parts, e.g. mountings, containers, diamond heatsinks
    • H01L21/4807—Ceramic parts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H01L23/14—Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
    • H01L23/15—Ceramic or glass substrates
    • 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
    • C03C2214/00—Nature of the non-vitreous component
    • C03C2214/04—Particles; Flakes
    • 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
    • C03C2214/00—Nature of the non-vitreous component
    • C03C2214/08—Metals
    • 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
    • C03C2214/00—Nature of the non-vitreous component
    • C03C2214/16—Microcrystallites, e.g. of optically or electrically active material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/095—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00 with a principal constituent of the material being a combination of two or more materials provided in the groups H01L2924/013 - H01L2924/0715
    • H01L2924/097—Glass-ceramics, e.g. devitrified glass
    • H01L2924/09701—Low temperature co-fired ceramic [LTCC]
    • 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
    • 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
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092—Dispersed materials, e.g. conductive pastes or inks
    • 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
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/46—Manufacturing multilayer circuits
    • H05K3/4644—Manufacturing multilayer circuits by building the multilayer layer by layer, i.e. build-up multilayer circuits
    • H05K3/4673—Application methods or materials of intermediate insulating layers not specially adapted to any one of the previous methods of adding a circuit layer
    • H05K3/4676—Single layer compositions

Definitions

  • This invention relates to glass-ceramic composite materials and co-fired metal-ceramic packages made therewith. Specific glass and metallization compositions are described as well as the processing steps.
  • Multi-layer devices for mounting semiconductor and microwave chips generally comprise alternating layers of insulating layers and conductive circuits to form a three- dimensional interconnected circuit package.
  • the insulating layers are generally composed of glass, ceramic, or a combination of the two; the conductive circuits are composed of a metallization composition.
  • the packages are typically produced by thick film printing circuit patterns onto insulating layers and laminating layers together. Circuit paths between layers are achieved by via holes, filled with a conductive metallization composition.
  • the thick film printing method has been used to fabricate hybrid circuits and multi-layer printed interconnect boards.
  • metal powders and ceramic powders are formulated into metallic (conductive) and dielectric (insulating) inks, and then alternately screen printed onto a fired ceramic base.
  • metallic (conductive) and dielectric (insulating) inks are formulated into metallic (conductive) and dielectric (insulating) inks, and then alternately screen printed onto a fired ceramic base.
  • two or three printings of dielectric material are required to achieve each insulating layer, and the circuit must be fired after each printing step.
  • this method is very time consuming because of the large number of printing and firing steps.
  • Ceramic layer hermeticity is a major problem affecting yields and is a direct result of using screen printing methods to form insulating layers.
  • conventional metal pastes contain active bonding agents to promote adhesion to the dielectric substrate (e.g., lead or lead oxide, bismuth or bismuth oxide, and zinc or zinc oxide are typically used in combination with borosilicate glasses to promote adhesion) .
  • active bonding agents e.g., lead or lead oxide, bismuth or bismuth oxide, and zinc or zinc oxide are typically used in combination with borosilicate glasses to promote adhesion.
  • green ceramic sheets e.g., containing a polymeric binder and ceramic particles
  • a monolithic interconnect structure a package
  • the ceramic green tape is fabricated by the doctor blade tape casting process from a slurry containing a mixture of ceramic powder, thermoplastic binder resin, solvent(s) , and other additives such as dispersants and plasticizers.
  • Polyvinyl butyral (PVB) is a commonly used resin binder for tape casting.
  • a green tape is blanked into sheets and registration holes are punched in it; via holes, mentioned above as providing electrical connections between adjacent layers, are also punched using fixed tooling or a numerically controlled punch press.
  • the via holes are filled with a metallization composition and circuit trace patterns are printed onto the sheet surface using a metallization composition; the metallization compositions (typically referred to as "inks") for traces and vias may be the same but are typically of differing compositions.
  • the individual sheets are then stacked in the proper sequence for the desired circuit pattern and laminated to form a solid, composite laminate.
  • the laminate is fired to decompose and remove the polymeric binder and to sinter the ceramic and metal particles, thereby forming a dense body containing the desired three-dimensional wiring pattern.
  • Aluminum oxide (alumina) because of its excellent electrical (insulating) , thermal, and mechanical (especially strength) properties has been the ceramic of choice for such substrates.
  • These ceramic bodies generally containing 90-96 wt.% alumina and 4-10 wt.% glass, require sintering temperatures above 1500 °C, which necessitates the use of refractory metals, such as molybdenum or tungsten, for the metallization compositions.
  • refractory metals have significantly lower electrical conductivity than metals such as copper; they also require a strongly reducing atmosphere during firing, which necessitates increased furnace system costs.
  • Alumina has been an adequate dielectric material for microelectronic packaging in the past; however, the advent of higher frequency and higher speed devices has made clear the deficiencies of the current material systems.
  • Alumina has a relatively high dielectric constant of about 9.9, causing high signal propagation delay and low signal- to-noise ratios (high crosstalk) .
  • alumina has a thermal expansion coefficient of 6.7 x 10 "6 /°C (20°-200 ' C range) as compared with 3.0-3.5 x 10 "6 /°C for silicon, which represents a significant mismatch in thermal expansion, thereby implying design constraints and reliability concerns (e.g., for "flip chips," thermal matching is more critical than in wire bonding where the wire can relieve some thermal stresses) .
  • the binders used to fabricate green tapes do not decompose cleanly during firing at low temperatures (200°-600° C) in the reducing atmospheres utilized; significant graphitic carbon is generated which requires a high temperature burnout treatment (1100°-1200° C) prior to raising the temperature to the peak firing condition.
  • a materials system which allows for co-sintering the dielectric substrate with a highly conductive metal such as copper, gold, or silver.
  • An integrated circuit (IC) package fabricated from such a system would have significantly improved signal transmission characteristics.
  • IC integrated circuit
  • a glass-ceramic material sinterable to a high density at temperatures less than 1000° C is desireable.
  • the binder material must depolymerize and burnout cleanly, which precludes the use of conventional binders such as PVB; PVB and similar polymers, on burnout, would result in a porous substrate and a carbonaceous residue, thereby deteriorating the desired mechanical and electrical properties.
  • the bonding agents and ink vehicle system should be compatible with gold, silver/palladium alloys, and copper, and should be free from bismuth- and/or lead-containing compounds.
  • glass-ceramics which are formed by melting a glass and then crystallizing from the melt; these compositions typically include nucleating agents such as zirconium oxide, titanium oxide, and tin oxide, and components such as zinc oxide can also function as nucleants.
  • nucleating agents such as zirconium oxide, titanium oxide, and tin oxide
  • zinc oxide can also function as nucleants.
  • Compounds such as zirconium oxide can typically be added to facilitate the densification of cordierite, but even the addition of fractional percentage quantities of zirconium oxide can greatly increase the dielectric constant by two, three, or more parts per million. Another area of consideration in fabricating co- fireable packages is the metallization compositions and firing atmosphere.
  • Kamehara et al. further disclose the addition of as much as 1% alkaline oxide (e.g., Na 2 0) to the glass- ceramic, which provides alkali ions that are known to enhance copper (and silver) migration into the glass during co-firing, which may lead to degradation of electrical and insulating properties of the respective areas of the package; for example, such compounds are ionic and thus conductive, leading to worse resistive properties such as a lower breakdown voltage.
  • alkaline oxide e.g., Na 2 0
  • the type of copper ink disclosed by Kamehara et al. is known to contain bismuth oxide and/or a lead borosilicate glass, which are subject to reduction to metallic bismuth and metallic lead during firing in the reducing atmosphere, an effect which may lead to degradation of the conductive properties.
  • Suita also includes a review of prior art in copper metallization, and accordingly is incorporated herein by reference. Suita, for example, also discloses the use of refractory metals to aid in copper oxide reduction to copper during firing, thus improving subsequent solder wetting. It has been additionally disclosed that copper-based inks can contain 1-4 wt.% copper oxide to improve adhesion of the copper to the ceramic. As mentioned above, inks currently available, designed primarily for thick film hybrids and multilayer boards, are inadequate for low temperature co-firing processes.
  • Typical ink compositions have vehicles including slow drying solvents, such as methacrylate oligomers or polymers dissolved in solvents such as ethyl cellulose, ⁇ -terpineol, butyl carbitol acetate, and butyl carbitol.
  • slow drying solvents such as methacrylate oligomers or polymers dissolved in solvents such as ethyl cellulose, ⁇ -terpineol, butyl carbitol acetate, and butyl carbitol.
  • Common bonding agents are lead, often used in borosilicate glass in amounts of about 45-65%, and bismuth oxide.
  • Alkali metal oxides Na 2 0, K 2 0
  • fluxes to reduce the viscosity of the glass during firing.
  • alkali ions are undesirable because they increase the fluidity of the glass during firing (i.e., act as a flux) and they also enhance migration of copper (in non-oxidizing atmospheres) and silver (in air) ions into the glass through ion exchange processes; depending on the degree of migration, metal migration degrades the electrical properties of the fired ceramic-metal package, and thus the concentration of alkali ions should be minimized. Additionally, alkali ions may leach out of the glassy bonding phase during exposure to moisture and thereby degrade the environmental stability of the package.
  • the metallization portion preferably includes copper, but can also include any metal having a relatively low melting point.
  • the insulating portion is a glass-ceramic composite including a ceramic filler and a borosilicate glass of a specified composition. By varying the composition of the composite, one can design for certain desired properties, especially for fracture strength, dielectric constant, and thermal expansion coefficient.
  • the insulating portion is a composite, that is, a combination of crystalline ceramic materials and a glassy phase.
  • the crystalline ceramic filler is alumina, spinel, cordierite, ullite, forsterite, quartz, or mixtures thereof.
  • the glassy portion is composed primarily of calcium oxide, boron oxide, and silicon dioxide, and may optionally contain magnesium oxide and/or aluminum oxide; the latter two components may be added for chemical and/or phase stability, depending upon the composition of the filler material.
  • the glass portion is essentially devoid of the fluxes and stabilizers common to prior art glasses.
  • the metallization ink includes predominantly a highly conductive, low melting metal, such as copper, silver, gold, or alloys or mixtures thereof, such as Ag/Pd
  • the ink includes amounts of the above glass and filler materials, as well as conventional solvents.
  • the glass-ceramic composite materials are formed into a tape using a binder having a ceiling temperature of not more than about 125" C. such that the binder essentially evaporates rather than burns out. Thereafter, via and circuit traces are formed on tapes, the tapes are laminated, and the entire assembly can be co-fired to produce a monolithic integrated circuit package.
  • Fig. 1 depicts the shrinkage of various metallized via compositions in comparison to the shrinkage of the composite substrate.
  • Fig. 2 depicts the shrinkage of various metallized trace compositions in comparison to the shrinkage of the composite substrate.
  • the low firing temperature materials of the present invention are "glass-ceramic composites" comprising a borosilicate glass and a ceramic filler.
  • the present glass- ceramic composites are unlike the prior art "glass- ceramics” in that the prior art materials are derived from glasses that are crystallized from a glass melt, while the present materials are derived from crystalline fillers and a glass and the final composite composition includes essentially the same ratio of crystalline material to glass as the starting materials (i.e., there is essentially no crystallization, at least not to the extent that an essentially polycrystalline body is formed by nucleating an amorphous glass body) .
  • the art has also used the term "glass-ceramic" to include glass-ceramic composites.
  • the preferred glass compositions are composed of 20-57% alkaline earth oxides, of which calcium oxide com- prises 50-100% and magnesium oxide comprises 0-50%, 23-40% silicon dioxide, and 20-35% boron oxide (all amounts are by weight percent unless otherwise specified) .
  • fritted glass compositions are 25-57% alkaline earth oxide, 23-35% silicon dioxide, and 25-35% boron oxide. Also for fritted glasses, reducing the alkaline earth oxide or boron oxide levels much below the above-described values, or increasing the magnesium oxide ratio much above the 50% level, leads to two-phase and sometimes devitrified glasses which may be difficult to batch and melt. Glasses which have phase separated, but have not devitrified, have been successfully employed, but are not generally preferred.
  • the filler material of the composite is generally a crystalline ceramic, including alumina, spinel, or almost any silicate-based oxide material, such as cordierite, mullite, forsterite, spodumene, eucryptite, quartz, or any combination of the foregoing.
  • the filler material and the glass can be chosen to emphasize a desired characteristic; for example, an alumina filler might be chosen because of the strength imparted to the fired product.
  • cc-cordierite yields composites with a lower thermal expansion coefficient, which more closely matches that for silicon, and a lower dielectric constant (about 5.5) .
  • crystalline quartz yields composites with a higher thermal expansion coe ficient and a very low dielectric constant of 4.5 to 5.5, depending on the glass used.
  • fused silica has been successfully employed; during firing the fused silica reacts with the glass to form a crystalline (primarily quartz and cristobalite) silica-glass composite. It is preferred that the filler not react excessively with the glass, because this results in uncontrolled shrinkage and excessive warpage during firing, and also generally leads to degraded properties, particularly fracture strength. To moderate the effects of any reactions, the filler or glass may be altered.
  • a mixture of fillers, one reactive and the second relatively inert may be combined to yield more desired net properties than the two separately.
  • alumina at ' 60% mixed with glass A yields high fracture strengths and dielectric constants of about 7.9
  • forsterite at 50% mixed with glass A reacts without densification during firing up to 1000° C.
  • a combination of the three constituents densifies acceptably and yields high fracture strength and reduced dielectric constant.
  • Detrimental reactions may also be overcome by a change in the glass composition.
  • cordierite combined with glass A dissolves slowly during firing at 850° C. and rapidly above about 900° C. to form additional glass and a small amount of an unidentified crystalline phase.
  • addition of magnesium oxide to the glass allows the cordierite-based composites to be fired at temperatures as high as about 950° C. with minimal cordierite dissolution, thereby yielding improved mechanical and dielectrical properties.
  • small additions of alumina as a co-filler results in improved fracture strength due to the reaction with the glass and anorthite formation.
  • a preferred embodiment of the invention is the combination of cordierite, alumina, and a calcium magnesium borosilicate (CMBS) glass to yield good net properties, particularly fracture strength
  • alumina-based composites (30,000 - 40,000 psi) , dielectric constant (about 5.5 - 6.5) and thermal expansion coefficient (approximately 3-4 x 10 "6 /°C at 20°-300° C) .
  • T > 800°C the specific presence of alumina and the dissolution of alumina into the glass during firing
  • An added benefit of this reaction is that the fired alumina- based composites may be heated for further processing (e.g., brazing) to temperatures near the peak firing temperature without causing warpage of the body.
  • Another preferred embodiment of the invention is the combination of quartz and glass with alumina and/or cordierite as a co-filler to yield comparable properties.
  • Another preferred embodiment of the invention is the use of magnesium oxide addition to the glass phase of the final composite.
  • Such addition can be through the use of a reactive filler, such as forsterite or cordierite added to a calcium borosilicate (CBS) glass, or through the use of a CMBS glass, to impart chemical stability to the fired composites.
  • CBS calcium borosilicate
  • Takabatake et al. disclose the addition of alumina to their glass composition to impart chemical stability, although alumina was not successful in the present case: during firing of Example 1 (alumina and a CBS glass) some alumina dissolves into the glass, but is subsequently consumed in forming anorthite, thereby leaving a residual borosilicate glass phase that is soluble in water.
  • the composite fails a water leaching test (two hours in boiling water for which ⁇ 1% weight loss is required) .
  • the addition of magnesium oxide to the composite significantly improves chemical stability; when anorthite forms during sintering, the magnesium oxide remains in the residual glass phase, thereby imparting stability.
  • silicate filler materials are necessarily compatible with all CBS or CMBS glasses. See also, for example, Muller, U.S. Pat. No.
  • the present invention achieves suitable and stable sintered composites without the addition of lead oxide, zirconium oxide, zinc oxide, bismuth oxide, or the like to the glass composition.
  • Dielectric materials of the invention are exemplified by the compositions and properties of Examples 1-23.
  • the insulating layers may be formed by mixing a fritted glass and particles of the refractory filler.
  • An alternative method is to form composite particles by a sol-gel coating method.
  • This sol-gel method although more complex than the mixing technique, provides advantages over that method.
  • One advantage is that the sol-gel method allows for the use and creation of glass compositions that are not formable from a melt. See, e.g., T. Hayashi and H. Saito, "Preparation of CaO-Si0 2 Glasses by the Gel Method," J. Mater. Sci. , vol. 15, p.
  • the sol-gel coated composite powders are fabricated by mixing a suspension of the filler particles with a solution of glassy reagent, and then adding a precipitating agent.
  • the precipitating agent causes the glassy component to coat the filler particles.
  • the composite powder is then separated from the solution, dried, calcined, and milled. Milling is required to break up the loosely aggregated product into a fine, single- particle population; the powder is then ready for further processing into green tape, as described below.
  • a slurry is formed by dispersing a filler powder with the aid of a dispersing agent (such as ⁇ -methacryloxypropyl silane) in dry isopropyl alcohol, although methanol and ethanol are equally suitable solvents.
  • a dispersing agent such as ⁇ -methacryloxypropyl silane
  • Other preferred dispersants include, but are not limited to, ethylene diamine, triethanolamine (TEOA) , triethylamine (TEA) , and ammonium hydroxide.
  • TEOA triethanolamine
  • TAA triethylamine
  • ammonium hydroxide Proper deagglomeration (dispersion) of the powder may be achieved by ball-milling, such a milling in a high vibratory mill, or by various other milling and mixing processes.
  • This solution is then added to the slurry and the two are mixed to form a homogeneous slurry.
  • a precipitating agent such as an aqueous solution of ammonium hydroxide, is added to the slurry to cause precipitation of the glass forming components onto and around the filler component; ammonium carbonate may also be present as a co-precipitating agent to aid in complete precipitation of the calcium (and magnesium) cations.
  • the resulting composite is separated from .the solution by, for example, spray-drying, or by centrifugation followed by drying at less than about 200° C.
  • the aggregate powder is calcined and then milled to the appropriate average size. Limited milling is also possible prior to calcining, but this step adds cost, and if prolonged, may cause degrada ⁇ tion of the coating.
  • Exemplary precipitating agents include hydroxides, carbonates, citrates, and the like.
  • Exemplary precursors include silicic acid, boric acid, aluminum, alkaline earth chlorides or similar salts, and the like. While not desirous of being limited to a particular theory, it should also be noted that the chemistry of this sol-gel technique is, or can be, driven by both chemical and electrostatic interactions. For example, the
  • 7-methacryloxypropyl silane functions not only as a dispersant for the fillers, but also acts to prepare the filler surface to more readily accept the precursor TEOS. Therefore, the dispersant functions chemically as a dispersant and to prepare the filler surface for precipitation.
  • the term “narrow size distribution” refers to particle distributions having a standard deviation not greater than about 100% of the mean particles size, preferably not greater than about 50%.
  • a preferred average particle size is 0.5-5.0 ⁇ m, more preferably not greater than about 3.0 ⁇ m. Nevertheless, it should be appreciated that the actual particle size is not critical to the practice of the present invention.
  • Glass D was a sol-gel composition.
  • e is the dielectric constant, and Diss. is the dissipation factor in percent (%) ; both are measured at 1 MHz. Fracture strength is in kpsi. Leachability is in percent weight loss.
  • C cordierite
  • G glass
  • Al alumina
  • An is anorthite
  • Q quartz
  • O for other. unidentified material(s).
  • Example 21 A glass-ceramic composite of the following composition was prepared: Alumina 40%; Quartz 20%; Glass 40% type E as above. The composite was sintered at 850° - 900° C. and yielded the following properties: IR (insulation resistance) of 13.3 ⁇ ; BDV (breakdown voltage) of 29.8 KV/mm; dielectric constant of 6.8-6.9; and T c ⁇ of 6 X 10 " V°C (for 20 - 300 °C).
  • Example 23 A composite of 48% cordierite, 10% quartz, and 42% of type E glass was fired at 850-900 °C and resulted in a dense body having the following properties: density of
  • the multi-layer interconnect packages are fabricated using sheets of green ceramic tape, which are punched with registration and via holes, metal inks are used for filling the via holes and for printing circuit traces, the sheets are laminated together, and then fired.
  • High yield fabrication of quality packages requires exacting properties from the green tape. Consistent and uniform particle packing density in the tape is particularly required for control of the green-to-fired shrinkage ratio. This consistency is strongly influenced by providing a well-dispersed system of powder particles in the casting slip, discussed more fully below.
  • the average particle size for the fillers and the glass frit, or for sol-gel coated filler should be between approximately 0.5 and 5 microns. It is preferred to extract the coarse portion of the particle size distribution to set the upper particle size at a desired limit, which can be accomplished by a centrifug- ation or sedimentation method; one such centrifugation method is described in U.S. patent application serial number 028,891, filed March 28, 1987, incorporated herein by reference.
  • the particle size distribution may be further narrowed by removing the fines portion below a desired particle size, by using the same methods.
  • the resultant controlled size distribution of fillers and glass for the mixed powder method or of coated filler from the sol-gel method yield tapes with superior reproducibility.
  • Fired microstructures are also improved using such powders; the preferred fine powders can yield finer grains and more uniform pore sizes and a more uniform distribution of pores, thereby resulting in more uniform dielectric/electrical properties (e.g., breakdown voltage) and mechanical properties (e.g., flexural strength) .
  • acceptable microstructures and properties for microelectronic and microwave substrates are possible using wide size distribution powders.
  • Green tapes are fabricated from slurries which contain at least one powder, a dispersant, a solvent, a polymeric binder, and optionally a plasticizer.
  • the polymeric binder is preferably an acrylic-acid based polymer or copolymer, and more preferably those derived from ⁇ -substituted methacrylate esters.
  • Another recent class of binders are polyalkylene carbonates (e.g., polypropylene carbonate), such as that described in JP 62-21753 (based on application JP 85156043) , and those available from Air Products and Chemicals, Inc., Emmaus, PA, under the designation QPAC. These are preferred because they have a low ceiling temperature, typically less than about 250°C.
  • methyl methacrylate has a ceiling temperature of approximately 220 ⁇ C; similarly, the QPAC binders decompose in air below 300°C and in inert atmospheres such as nitrogen and argon below 380°C. This property is useful when low firing and organic burnout temperatures are required.
  • the ceiling temperature is a thermodynamic property at which the free energy of polymerization under the prevailing conditions is zero, and above this temperature polymerization to long-chain polymer is impossible (just as in a physical system a liquid cannot form a solid when the temperature is above the melting point, or the pressure is too low, etc. (i.e., the prevailing conditions) ) .
  • the ceiling temperature is well above the normal temperature range for polymerization, for many monomers the ceiling temperature lies within the temperature range normally encountered for polymerization.
  • Exemplary preferred polymeric binders include those available under the designations ELVACITE-2046 (hereinafter termed "E-2046”) , E-2014, E-2016, and E- 2028, " (all available from E.I. duPont de Nemours. & Co., Wilmington, DE) which are, respectively, a copolymer of n-butyl methacrylate/isobutyl methacrylate, a methacrylic acid modified methyl methacrylate copolymer, a methyl/n-butyl methacrylate copolymer, and a methyl/n-butyl methacrylate copolymer.
  • E-2046 E-2014, E-2016, and E- 2028, " (all available from E.I. duPont de Nemours. & Co., Wilmington, DE) which are, respectively, a copolymer of n-butyl methacrylate/isobutyl methacrylate, a methacrylic acid modified
  • the dispersant is used to provide a well-dispersed slurry, that is, where the particles (filler and glass) are present as individual particles rather than agglomerates. In the green tape, a good dispersion yields improved strength, integrity, coherence, and good particle packing.
  • the dispersant must be compatible with the other components and should strongly adsorb onto the powder surface to impart colloidal stability to the particulate slurry.
  • the dispersant since the physical properties of the tape are dominated by the polymer- particle interactions, the dispersant must provide for strong polymer bonding to the particle surfaces; the dispersant can create the opportunity for bonding by acting as a surface active agent, it can enhance bonding as a coupling agent, it can allow bonding by decreasing repulsive electrostatic forces, and so forth.
  • Suitable dispersahts include, but are not limited to, fish oil and similar fatty acid derivatives (e.g., SPAN 85, a nonionic sorbitan trioleate available from ICI Americas, Wilmington, DE) , polyalkoxy quaternary ammonium salts (e.g., EMCOL CC-55, a cationic polypropoxy quaternary ammonium acetate, as well as EMCOL CC-42 and EMCOL CC-36, all available from Witco Chem.
  • fish oil and similar fatty acid derivatives e.g., SPAN 85, a nonionic sorbitan trioleate available from ICI Americas, Wilmington, DE
  • polyalkoxy quaternary ammonium salts e.g., EMCOL CC-55, a cationic polypropoxy quaternary ammonium acetate, as well as EMCOL CC-42 and EMCOL CC-36, all available from Witco Chem.
  • Organometallic coupling agents are also suitable, and those having an alkoxy group are especially preferred.
  • Exemplary coupling agents include silanes such as ⁇ -methacryloxypropyltrimethoxy silane (e.g., Z-6030 brand, available from Dow-Corning Chem. Corp.
  • organometallics such as diisobutyl (oleyl)-acetoacyl aluminate, isopropyl triiso- stearyl titanate (e.g., titanium (IV), 2-propanolate, tris isooctadecanoato-O, available as KR TTS from Kenrich Petrochemicals, Bayonne, NJ) , alkoxy, acryl titanates (e.g., titanium (IV), tris methacrylate, methoxydiglycolato, available from Kenrich as KR 33OS, and isopropyl dimethacryl isostearoyl titanate, available as KR 7), tetra(2,2 diallyloxymethyl-1 butoxy titanium di(di-tridecyl) )phosphite (e.g., KR 55, available from Kenrich) , titanium (IV) neoalkanolato, tris (3-amino) phenolato-0 (available as LICA
  • a result of strong coupling between the polymeric binder and the powder is that the tape has superior thermomechanical properties.
  • An additional advantage is that the tape possesses excellent dimensional stability.
  • a tape made in accordance with this invention may typically experience a shrinkage of less than 0.1 mil/inch per thermal cycle (room temperature to greater than 60°C) . These attributes significantly improve fabrication yield, especially for large multilayer interconnect packages.
  • the plasticizer may be any conventional plasticizer, such as an aromatic diester.
  • Preferred plasticizers are those such as PX-316 (a mixture of n-hexyl, n-octyl, and n-decyl phthalates available from USS Chemicals, Pittsburgh, PA) , SANTICIZER 160 (a butyl benzyl phthalate available from Monsanto Co., St. Louis, MO), DUP (di ndecyl phthalate, also available from Monsanto) , and DOA (dioctyl adipate, available from Hexagon Enterprises Inc., Mountain Lakes, NJ) .
  • PX-316 a mixture of n-hexyl, n-octyl, and n-decyl phthalates available from USS Chemicals, Pittsburgh, PA
  • SANTICIZER 160 a butyl benzyl phthalate available from Monsanto Co., St. Louis, MO
  • DUP di ndecyl phthalate, also available from Monsant
  • the binder content of the green tape is approximately 34-50 volume percent, more preferably about 38-45 volume percent.
  • The.weight ratio of binder to plasticizer should generally be from about 1:1 to about 6:1. In specific embodiments, when E-2046 is used as the binder, the ratio is preferably 4:1; when the other ELVACITE brand binders are used, the preferred ratio is 3:1.
  • Solvents for the polymeric binder and the plasticizer(s) include a variety of alcohols (e.g., ethanol, propanol) , ketones (e.g., methylethyl ketone (MEK) , methylisobutyl ketone (MIBK)) , acetates, aromatics (e.g., toluene, xylene) , and mixtures of these.
  • Preferred solvents include a 1:1 (weight basis) mixture of MEK:toluene and a 60:40 (weight basis) mixture of MIBK:n-propanol.
  • Tape slurries are preferably prepared using a two phase milling process, although conventional tape preparation methods are equally suitable even though not necessarily preferred.
  • the solvents, dispersant, powder, and grinding media are ball-milled for about 24 hours.
  • the polymer and plasticizer are added to the mixture and are ball-milled for an additional 24-48 hours.
  • the slurry is then deaired, optionally and preferably filtered, and cast using the doctor blade technique.
  • the precise formulations will vary depending on physical characteristics of the starting powders.
  • the present tape systems have been found to be suitable for transfer tape applications (see, e.g., Vitriol et al., Proc. of ISHM, 1986, p. 487-495).
  • the key aspects of the present tape is its ability to be laminated to a dense substrate, such as 96% alumina, without deformation of any prepunched vias or cavities.
  • a dense substrate such as 96% alumina
  • the tape may be used in conjunction with alumina or other high thermal conductive substrates, such as refractory metals (molybdenum, tungsten) , silicon carbide, aluminum nitride, and those having a low thermal expansion coefficient.
  • refractory metals mobdenum, tungsten
  • silicon carbide silicon nitride
  • those having a low thermal expansion coefficient such as refractory metals (molybdenum, tungsten)
  • the latter class of materials require firing in a neutral or reducing atmosphere (nitrogen or nitrogen-hydrogen) , thus making a tape requiring convention oxidative binder burnout virtually impossible to employ, while the present systems is particularly well-suited for this application.
  • Example 24 A 45/15/40 weight ratio mixture of alumina/forsterite/glass was prepared, the CBS glass having a composition of CaO/B 2 0 3 /Si0 2 as 38.0/31.5/30.5 by weight ratio.
  • the alumina was crystalline and was from a 0.3 - 1.2 ⁇ m size cut obtained by centrifugal classification techniques, such as those described in PCT/US88/01008, filed 23 March 1988, and the priority documents described therein, all incorporated herein by reference; the forsterite and CBS glass were used as- received.
  • the powder was milled for 24 hours along with 29 wt.% of a 1:1 mixture of MEK:toluene and Z-6030 silane ester dispersant (2 wt.% based on powder weight) .
  • a tape was cast from this slurry and showed excellent green strength and laminating properties, such as tensile strength, tensile modulus, shrinkage, and so forth.
  • the total binder content in the dried tape was 43 vol.%.
  • Example 25 Following the general procedure of Example 24, approximate amounts of the following components were mixed in a first stage milling procedure: 1045 g. MEK
  • Powder sizes are given " in average particle size.
  • the polymeric binder was a butyl methacrylate -(ELVACITE- 2046)
  • the plasticizer was a mixed phthalate (PX-316)
  • the dispersant was 7 -methacryloxypropyl silane.
  • the resultant tapes possessed superior thermomechanical properties.
  • the tape of Example 26 had a tensile strength of 1850 and a tensile modulus of 98,000 psi; the tape was very stable dimensionally, even during repeated heating cycles typically experienced during metal ink drying (up to about 120°C) ; shrinkage of less than 0.1 mil/inch occurred per heating cycle.
  • This tape also laminates well at 75°C and pressures of 1500 to 3000 psi. Sintering parameters are generally given for Examples 1-23.
  • the conductive inks employed in the present invention generally contain a metal powder, bonding agents, dispersant, solvent, and polymeric binder; that is, essentially metal/bonding agent and vehicle; other components may optionally be present to adjust the rheology or other properties of the fired metallization.
  • Typical inks generally have 70-92 wt.% solids with the remainder composed of the vehicle system. Low temperature co-firing, and especially firing in a reducing atmosphere, makes inks currently used essentially unusable in the present invention.
  • the metal powder is preferably composed of copper, silver, silver/palladium alloys, gold, gold/platinum alloys, and similar alloys and mixtures thereof; these metals are preferred because of their high electrical conductivity.
  • the metal powder is copper and has an average particle size of 1 - 10 ⁇ m. While it is most preferred to use powders having a relatively narrow size range (such as copper powder #12, available from Metz Metallurgical, South Plainfield, NJ) , the present invention is equally applicable to metal powders having conventional sizes and distributions.
  • a further embodiment uses a blend of discrete sized particle populations to control the shrinkage during firing.
  • the bonding agent promotes adhesion between the ceramic and the metal upon firing.
  • Such agents generally are composed of a calcium magnesium borosilicate (CMBS) glass plus one of cordierite, forsterite, alumina, quartz, or other low thermal expansion silicates such as eucryptite or spodumene, or a combination of these.
  • CMBS calcium magnesium borosilicate
  • cordierite forsterite
  • alumina alumina
  • quartz or other low thermal expansion silicates
  • the bonding agent can also include inert fillers which control shrinkage during sintering; matching shrinkage between the dielectric and the metallization also results in better bonding.
  • the vehicle system is generally comprised of solvent(s), polymeric binder, and dispersant; a plasticizer and additional components may be present to modify the properties of the ink or printed patterns.
  • solvents for inks generally include aliphatic alcohols, acetates, propionates, and terpenes
  • the preferred solvent for copper inks is ⁇ -terpineol
  • silver, silver/palladium, or gold inks butyl carbitol or butyl carbitol acetate used with ⁇ -terpineol (to control viscosity) is preferred.
  • the preferred polymers for the inks are polymethyl- methacrylates of the lower alcohols, with butyl methacrylate being the most preferred; generally preferred are the ELVACITE brand polymers described above.
  • Plasticizers and dispersants such as those mentioned above are suitable; dispersants are generally present in amount of 0.5-2.0 wt.% of the solids portion, and are generally added to improve the viscosity and printing characteristics of the ink.
  • the preferred approximate solids content (i.e., metal plus bonding agent) of the inks are as follows: for trace inks, 80-97 vol.% metal with the 3-20 vol.% remaining composed of additives and so forth for bond promotion and other desired properties; for via inks, 40-
  • More preferred solids compositions for ink formulations are: for traces, 84-97 vol.% copper, 1-10 vol.% alumina and/or other ceramics (e.g., cordierite, quartz; as mentioned above), and 1-8 vol.% CMBS glass; and for vias, 50-70 vol.% copper, 5-30 vol.% of at least one of alumina and " quartz, 0-35 vol.% cordierite and/or low thermal expansion ceramic (e.g. , eucryptite, spodumene), and 10-30 vol.% CMBS glass.
  • alumina and/or other ceramics e.g., cordierite, quartz; as mentioned above
  • CMBS glass for vias, 50-70 vol.% copper, 5-30 vol.% of at least one of alumina and " quartz, 0-35 vol.% cordierite and/or low thermal expansion ceramic (e.g. , eucryptite, spodumene), and 10-30 vol.% CMBS glass.
  • the firing temperature of the copper inks is generally between 700° and 950"C. Although pure copper sinters at the lower temperatures (about 650°-800°C) , the co-firing of copper with the glass-ceramic composite dielectric is generally accomplished at 875°-950 ⁇ C.
  • one objective of the present invention is to delay the sintering of copper to minimize the mismatch in shrinkage behavior between the copper and the glass-ceramic composite, while maintaining the desired electrical properties of copper. Additions to the ink, where these constituents comprise some of the components of the glass-ceramic composite, are effective in significantly delaying the sintering process with respect to the copper, which also improves the shrinkage match.
  • Shrinkage control of the metallization is highly dependent on the glass:ceramic ratio, even though the combined glass and ceramic components of the metallization may be quite small in comparison to the amount of metal present. It should also be noted that shrinkage control includes (i) a final matching of the fired ceramic (glass-ceramic composite) to the metallization (e.g., no cracks) and (ii) shrinkage of the substrate and the metallization at the same rate.
  • Additional retardation may be desireable and can be effected by the addition of copper oxide (less than about 5 wt.%) to the ink.
  • copper oxide may be employed to retard sintering of the copper.
  • Copper oxide may be added as a powder, or, preferably achieved through an oxidation treatment of the copper powder (200°-500°C in air) .
  • An alternative approach is to co-fire at elevated oxygen levels (e.g., 30-100 ppm oxygen) and thus partially oxidize the copper prior to reaching sintering temperatures (less than approximately 650°C) .
  • the copper oxide may be reduced by the introduction of hydrogen into the atmosphere at a desired temperature; sintering of the copper accelerates once the copper oxide is adequately reduced.
  • a preferred embodiment of the present invention is the use of copper oxide to delay sintering of the copper, thereby providing for improved shrinkage match between the copper and the ceramic dielectric.
  • Inks made in accordance with the present invention showed good printing characteristics and, upon sintering, adhered well to the ceramics.
  • Typical resistivities for trace inks were approximately 1-2 m ⁇ /square, and for via inks the typical resistivities were approximately 3-8 m ⁇ /via; vias have a 10 mil diameter on a 10 mil tape thickness.
  • the present inks are more readily appreciated with reference to the following examples. Examples 32 - 38
  • Example 39 The solids formulations of Examples 32-38 were mixed with a "vehicle" containing 25 wt.% E-2046 brand and 75 wt.% ⁇ -terpineol, and 1 wt.% of EMCOL CC-36.
  • the total composition of the vehicle system was from 9-12% of the - total weight of all of the ingredients.
  • the volume of the organics made up 48-57% of the total volume of the paste. If the viscosity of the paste required adjustment, additional ⁇ -terpineol (5-15% of the original weight) or additional vehicle was added.
  • Example 40 This example illustrates the effect of copper oxide on sintering rates. Copper pellets were made by pressing copper #12 powder (available from Metz Metallurgical, South Plainfield, NJ) to a green density of 64%. Samples were subjected to the following oxidation treatment: Temperature Time Weight % Increase
  • Oxidized and non-oxidized pellets were sintered in a nitrogen atmosphere. The temperature was raised to peak temperatures (shown below) at the rate of 20°C/min. The following table shows the densities (as percents of the theoretical density) of the pellets. 900°C lOOO'C oxidized 65-75% 80-85% non-oxidized 90-91% >95% Samples which were oxidized prior to firing underwent a reduction reaction at their surface, thereby forming a metallic copper "skin" surrounding the pellet of oxidized copper, whereas the internal region of the pellets showed poor sintering.
  • Examples 41-50 These examples illustrate the effect of the glass:ceramic ratio and the metal powder particle size on shrinkage.
  • the copper powder was obtained from Metz Metallurgical as #12 (average particle size of 6.5 ⁇ m) and as #13 (average particle size of 11 ⁇ m) .
  • Silica and alumina (and cordierite for the traces) represented the filler components for the glass.
  • the composite substrate was 40% alumina, 20% quartz, and 40% of the same CMBS glass.
  • Example 45 The resistivity of Example 45 was 0.58 m ⁇ /via (10 mil
  • Example 43 shows that with no glass, there is essentially no shrinkage upon sintering.
  • examples 44 and 45 show that a glass:ceramic ratio of 18:22 (w 0.82) provides a very good match to the substrate as opposed to a ratio of 10:30 (w 0.33). Accordingly, a comparison among examples 41, 44, and 45 provides a good illustration of the effect
  • Examples 46 and 47 were, respectively, 1.53 m ⁇ /square and 1.6 m ⁇ /square.
  • Fig. 2 The results of sintering these compositions are depicted in Fig. 2; again, the glass-ceramic composite substrate is shown as the solid circles; copper without any glass or ceramic is shown as the open circles. Also, the all of these examples used the 6.5 ⁇ m size copper powder. Again it is seen that with no glass (example 49) there is no shrinkage. With examples 46-48a glass:ceramic ratio between 0.67 and 0.43 reasonably approximates the shrinkage of the substrate. Also, comparing examples 48 and 50, the shrinkage appears to be more dependent upon the glass:ceramic ratio than upon the amount of metal present.
  • the temperatures for firing the packages of the present invention are typically less than 1000°C, and generally about 850°-975°C.
  • the range is about 875°-975°C; for cordierite-based and alumina-based packages the range is about 850°-950°C.
  • temperatures of over about 1000°C result in excessive reactions and degradation. It was found that the alumina and glass produce anorthite and the result is a substrate which does not become dense and is not hermetic.
  • the package has a glassy appearance rather than a polycrystalline one, and migration of the metal may be a problem.
  • the package has the desired icrostructure with little or no metal ion migration.
  • the dielectric layers may contain a number of phases, including, but not limited to: cordierite; spinel; glass; alumina; quartz; anorthite; and other silicate or material phases.
  • the firing schedule In general, in addition to providing densified dielectric and metallic portions, other objectives of the firing schedule are to control the evolution of the binder and to control the carbon content. Control of the binder "burnout" can be used to avoid delamination of the package. Control of the carbon content helps to achieve the desired electrical and dielectrical properties. In preferred embodiments, the carbon content is controlled to ⁇ 250 ppm prior to the peak sintering temperature, and to ⁇ 150 ppm in the final composite.
  • the most preferred firing schedule for copper co- firing controls time, temperature, and the atmosphere, and has two thermal regions; a low temperature region ( ⁇ 800°C) for binder removal by depolymerization and evolution of the binder and by oxidation of the carbon residue, and a high temperature region (>800°C) for sintering.
  • the heating rate should be l-3°C/min and can be increased to 3-6°C/min after a temperature of about 350°C is attained; alternatively, the temperature can be held (a "soak") at 200-225°C for 1-6 hours at which binder evolution is beginning.
  • the temperature is maintained for 1-12 hours, preferably about 6-8 hours for a seven layer package, to ensure complete removal of the binder residue by oxidation.
  • All of the foregoing steps are preferably conducted in a wet nitrogen atmosphere with 1-20 ppm oxygen and 2-15% water; oxygen may be decreased to 10 " * ppm if a hydrogen dopant forming gas is used; conversely, up to approximately 100 ppm oxygen may be used to enhance carbon removal and/or to retard copper sintering.
  • oxygen may be present due to impurities in the nitrogen; water is used to oxidize the evolved monomers.
  • the oxygen content can be controlled by using a mixture of gases, such as including nitrous oxide, a carbon monoxide/carbon dioxide mixture, and the like.
  • gases such as including nitrous oxide, a carbon monoxide/carbon dioxide mixture, and the like.
  • Forming " gas if desired, may be mixed with the nitrogen to reduce the oxygen partial pressure.
  • the soak times are dependent upon the number of layers and the binder content in the green package, and the water and oxygen contents of the atmosphere.
  • the firing schedule is preferably heating from room temperature to 500°-600°C at 2-3°/min.; binder removal occurs generally within this temperature range. Unlike the procedure used with copper co-firing, there is no need to hold this temperature for an extended period of time in order to obtain less than approximately 250 ppm carbon. Heating can thereafter continue at a more rapid rate until a firing temperature of about 850°-950°C is reached.
  • a key aspect is the ability to fully laminate the tape to a dense substrate, such as >96% alumina, without any deformation of any prepunched vias or cavities.
  • a dense substrate such as >96% alumina
  • the dielectric tape should shrink in one direction to form a dense layer without closing down via holes.
  • the dielectric material have a thermal expansion coefficient closely matching that of the substrate to avoid excessive camber upon firing and cooling.
  • the alumina- and quartz-based composites satisfy these requirements for alumina substrates, while the cordierite-based composites are ideal for high thermal conductive substrates, such as refractory metals (molybdenum, tungsten) , and silicon carbide and aluminum nitride, which have a low thermal expansion coefficient.
  • the latter class (SiC and A1N) of substrates requires sintering in a neutral or reducing atmosphere.
  • thermal expansion coefficients for the composite also allows for the use of metallic plates brazed onto the bottom of the fired packages.
  • Metals such as molybdenum, tungsten, and tungsten-copper alloys have thermal expansion coefficients of 4.5-6 x 10 "6 /°C, which are in the range provided by the present invention for the dielectric materials. Because of this match, plates of refractory metal or ceramic such al aluminum nitride or silicon carbide may be brazed onto the bottom of fired laminates to provide packages having very high thermal dissipation characteristics.
  • a preferred embodiment of the present invention involves the combination in a package of a low temperature co- fireable substrate with a high thermal conductivity plate.
  • Lamination is generally at 60-90°C and at pressures of about 500-1500 psi, as is typical in the art, and as used herein.

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Abstract

La présente invention se rapporte à des boîtiers en métal/composite conjointement frittables ainsi qu'à des procédés pour leur production. La partie composite, pour présenter des propriétés diélectriques, se compose d'un mélange de matériau céramique cristallin et de matériau céramique vitreux. Par une opération de cuisson conjointe, les quantités relatives des parties cristallines et vitreuses restent essentiellement constantes. La partie diélectrique peut être fabriquée par mélange de poudres cristallines et de frittes vitreuses. Dans une autre variante, un procédé d'enduction sol/gel peut être utilisé pour produire une poudre composite (c'est-à-dire des particules cristallines enduites de constituants vitreux). La partie de métallisation est généralement constituée par du cuivre, par une combinaison argent/palladium ou par de l'or. Pour permettre la fabrication de ces boîtiers par des procédés de coulage en bande, on utilise de préférence un liant polymère qui se décompose (tel qu'un méthacrylate) plutôt qu'un liant qui brûle (tel que du butyrale de polyvinyle), ce qui est essentiel lorsqu'une atmosphère neutre ou réductrice est utilisée pour éviter l'oxydation du métal utilisé pour les chemins des circuits pendant l'opération de frittage. Un avantage de la présente invention réside dans le fait que les boîtiers peuvent subir une opération de cuisson conjointe à des températures inférieures à environ 1000°C. Ces boîtiers présentent également de bonnes propriétés électriques et physiques.
PCT/US1988/002788 1987-08-13 1988-08-15 Boitiers en metal/ceramique conjointement frittables et materiaux utilises pour leur fabrication WO1989001461A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
US8595187A 1987-08-13 1987-08-13
US07/085,078 US4788046A (en) 1987-08-13 1987-08-13 Method for producing materials for co-sintering
US085,078 1987-08-13
US085,950 1987-08-13
US07/085,950 US4861646A (en) 1987-08-13 1987-08-13 Co-fired metal-ceramic package
US085,077 1987-08-13
US085,951 1987-08-13
US07/085,077 US5062891A (en) 1987-08-13 1987-08-13 Metallic inks for co-sintering process

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DE4024612A1 (de) * 1989-08-05 1991-02-07 Nippon Denso Co Keramisches, mehrfach geschichtetes substrat und herstellungsverfahren
EP0421694A1 (fr) * 1989-10-06 1991-04-10 International Business Machines Corporation Empaquetage électronique comportant des traversées hermétiques et procédé et appareil pour sa fabrication
EP0455486A1 (fr) * 1990-05-03 1991-11-06 Hoechst Celanese Corporation Procédé pour enlever un liant polyacétal de corps verts moulés en céramique par des gaz acides
EP0478971A2 (fr) * 1990-09-04 1992-04-08 Aluminum Company Of America Composition diélectrique contenant de la cordiérite et du verre
WO1993006053A1 (fr) * 1991-09-26 1993-04-01 International Business Machines Corporation Substrat a faible constante dielectrique et procede de fabrication
EP0672639A1 (fr) * 1994-01-24 1995-09-20 Hewlett-Packard Company Pâte pour boucher des trous dans des substrats céramiques
EP1153896A1 (fr) * 2000-04-26 2001-11-14 Matsushita Electric Industrial Co., Ltd. Composition céramique diélectrique,sa méthode de production et appareil de communication utilisant cette composition
WO2016004047A1 (fr) * 2014-07-02 2016-01-07 Corning Incorporated Séchage par pulvérisation d'un matériau en lot mélangé pour une fusion plasmatique
CN113402283A (zh) * 2020-03-16 2021-09-17 中国科学院上海硅酸盐研究所 一种低温共烧陶瓷基板及其制备方法
CN115894002A (zh) * 2022-12-06 2023-04-04 中国科学院合肥物质科学研究院 一种双相陶瓷增强低温共烧陶瓷材料及其制备方法和用途
EP3454998B1 (fr) * 2016-05-13 2023-10-11 Mantle Inc. Procédé de fabrication additive pour le dépôt d'une pâte métallique

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DE2755935A1 (de) * 1976-12-27 1978-07-06 Philips Nv Dielektrische zusammensetzung, siebdruckpaste mit einer derartigen zusammensetzung und durch diese erhaltene erzeugnisse
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EP0421694A1 (fr) * 1989-10-06 1991-04-10 International Business Machines Corporation Empaquetage électronique comportant des traversées hermétiques et procédé et appareil pour sa fabrication
EP0455486A1 (fr) * 1990-05-03 1991-11-06 Hoechst Celanese Corporation Procédé pour enlever un liant polyacétal de corps verts moulés en céramique par des gaz acides
EP0478971A3 (en) * 1990-09-04 1993-03-10 Aluminum Company Of America Dielectric composition containing cordierite and glass
EP0478971A2 (fr) * 1990-09-04 1992-04-08 Aluminum Company Of America Composition diélectrique contenant de la cordiérite et du verre
WO1993006053A1 (fr) * 1991-09-26 1993-04-01 International Business Machines Corporation Substrat a faible constante dielectrique et procede de fabrication
EP0672639A1 (fr) * 1994-01-24 1995-09-20 Hewlett-Packard Company Pâte pour boucher des trous dans des substrats céramiques
EP1153896A1 (fr) * 2000-04-26 2001-11-14 Matsushita Electric Industrial Co., Ltd. Composition céramique diélectrique,sa méthode de production et appareil de communication utilisant cette composition
US6579817B2 (en) 2000-04-26 2003-06-17 Matsushita Electric Industrial Co., Ltd. Dielectric ceramic composition and method for producing the same, and device for communication apparatus using the same
WO2016004047A1 (fr) * 2014-07-02 2016-01-07 Corning Incorporated Séchage par pulvérisation d'un matériau en lot mélangé pour une fusion plasmatique
EP3454998B1 (fr) * 2016-05-13 2023-10-11 Mantle Inc. Procédé de fabrication additive pour le dépôt d'une pâte métallique
CN113402283A (zh) * 2020-03-16 2021-09-17 中国科学院上海硅酸盐研究所 一种低温共烧陶瓷基板及其制备方法
CN115894002A (zh) * 2022-12-06 2023-04-04 中国科学院合肥物质科学研究院 一种双相陶瓷增强低温共烧陶瓷材料及其制备方法和用途
CN115894002B (zh) * 2022-12-06 2023-09-22 中国科学院合肥物质科学研究院 一种双相陶瓷增强低温共烧陶瓷材料及其制备方法和用途

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