GB2209521A - Green tape - Google Patents

Green tape Download PDF

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Publication number
GB2209521A
GB2209521A GB8721189A GB8721189A GB2209521A GB 2209521 A GB2209521 A GB 2209521A GB 8721189 A GB8721189 A GB 8721189A GB 8721189 A GB8721189 A GB 8721189A GB 2209521 A GB2209521 A GB 2209521A
Authority
GB
United Kingdom
Prior art keywords
layer
composition
layer according
inorganic binder
dielectric
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
GB8721189A
Other versions
GB8721189D0 (en
Inventor
Charles Edmund King
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ERA Patents Ltd
Original Assignee
ERA Patents Ltd
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
Application filed by ERA Patents Ltd filed Critical ERA Patents Ltd
Priority to GB8721189A priority Critical patent/GB2209521A/en
Publication of GB8721189D0 publication Critical patent/GB8721189D0/en
Publication of GB2209521A publication Critical patent/GB2209521A/en
Pending legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture 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
    • H01L21/48Manufacture 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
    • H01L21/4803Insulating or insulated parts, e.g. mountings, containers, diamond heatsinks
    • H01L21/4807Ceramic parts
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/6303Inorganic additives
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00Fixed capacitors; Processes of their manufacture
    • H01G4/002Details
    • H01G4/018Dielectrics
    • H01G4/06Solid dielectrics
    • H01G4/08Inorganic dielectrics
    • H01G4/12Ceramic dielectrics
    • H01G4/1209Ceramic dielectrics characterised by the ceramic dielectric material
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00Fixed capacitors; Processes of their manufacture
    • H01G4/002Details
    • H01G4/018Dielectrics
    • H01G4/06Solid dielectrics
    • H01G4/08Inorganic dielectrics
    • H01G4/12Ceramic dielectrics
    • H01G4/129Ceramic dielectrics containing a glassy phase, e.g. glass ceramic
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/12Mountings, e.g. non-detachable insulating substrates
    • H01L23/14Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
    • H01L23/15Ceramic or glass substrates
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/0002Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/095Indexing 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
    • H01L2924/097Glass-ceramics, e.g. devitrified glass
    • H01L2924/09701Low temperature co-fired ceramic [LTCC]

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

A green tape, in the form of a layer of substantially uniform thickness, is composed of a dielectric material and an inorganic binder. The dielectric material may be e.g. alumina, silica, lead borosilicate glass or alumina borosilicate glass. The inorganic binder may be e.g. selected from phosphates, silicates, borates, polyphosphates, polysilicates polyborates or polyacids of a transition metal.

Description

GREEN TAPE FIELD OF THE INVENTION The present inventIon relates to green tapes, their production and use.
BACKGROUND OF THE INVENTION Green tapes are used in the production of multichip capacitors and hybrid circuit chips. Such products can be produced by screen-printing each of the alternating layers of dielectric and conducting layers. However, screen-printing of the dielectric often leaves pinholes which can only be covered by superimposition of screen-printed materials.
It may therefore be preferred, and it is often convenient, to screen-print a metal on to a pre-formed green tape which consists essentially of a particulate dielectric material and a binder. The green tapes are produced by doctoring a suitable composition including a diluent on to an inert material, followed by slow drying.
The dried tapes are flexible and can be removed from the inert material.
In the past, organic binders have been used to provide green strength by forming a self-supporting and flexible matrix holding the 'permanent' solids content.
By permanent is meant the particulate matter of dielectric which give the fired tape the characteristic dielectric properties.
After construction of the multi-layer product, it is compressed, usually at an elevated temperature, and then subjected to burnout. Burnout is caused by firing at 600-1000 C, during which process the organic binder constituent is allowed to burn off prior to the sintering and densification stages. However, substantial difficulty in processing occurs because of the reluctance of organic binders to leave the product completely and cleanly during the 'burnout' stage.
Processing difficulties arise as a result of retained carbonaceous material leading to the reduction of certain metal oxides. Metal oxide reduction by carbon to give carbon monoxide or carbon dioxide can lead to blistering and poor adhesion in multi-layer circuits.
Also volatilisation and redeposition of low melting point metals formed by reduction can occur in unwanted areas.
Moreover the large volume of binder content used in the manufacture of green tapes will generally lower the overall densification during firing, resulting in substantial porosity. If high density products are necessary then a significant reduction in volume will occur during the firing process. Large dimensional changes lead to difficulty in alignment if subsequent screen printing operations are to be carried out on the fired product.
SUMMARY OF THE INVENTION A layer according to the invention (which for convenience may be termed a "green tape") is of substantially uniform thickness and of a composition which comprises a dielectric material and an inorganic binder. The invention thus avoids the use of organic binders.
DESCRIPTION OF THE INVENTION A green tape of the invention may be produced by applying the composition in admixture with a diluent on to an inert substrate, levelling the composition to the substantially uniform thickness, drying the composition, and (if desired) removing the layer of the dried composition from the insert substrate. The inert substrate is a layer of, for example, Mylar.
The dielectric or 'permanent' component is e.g. a dielectric compound such as a fine powder frit of lead borosilicate glass. The amounts of the various constituents as applied may be, for example, 10-70% by weight binder solids, 5-45% by weight diluent and 5-85% by weight of the dielectric component. The dried green tape may comprise 9-94% binder solids and 6-91% dielectric.
The binder is preferably a phosphate, silicate, borate, polyphosphate, polysilicate or polyborate or a polyacid of a transition metal. Most of these materials are polymeric in nature to some extent. The term "polyacid" includes heteropolyacids such as tungstosilicic acid.
Especially preferred inorganic binders are a) potassium polyphosphate and b) aluminium acid phosphate which in an aqueous or organic system provide the necessary rheological characteristics and when dried the required 'green strength' for the green tape. Potassium polyphosphate (KPO3)n is an example of#a generic group of mono and mixed metal polyphosphates and may be made by a variety of methods of which a simple route applicable to laboratory production is the thermal dehydration of potassium dihydrogen orthophosphate (KH2PG4). After an appropriate time at temperature the melt is quenched to give soluble long-chain polyphosphate. Aluminium acid phosphate is also made by a variety of methods of which the mixing of fine alumina powder with phosphoric acid is the preferred example.A molar ratio of P205 : Al O of between 1 : 1.5 and 3 : 1 may be used. However, preference is given to lower ratios.
Water and/or a volatile organic compound may be used as a diluent. Organic diluents, b their nature, are completely removed during the drying process.
The binder component (a) or (b) above when in a suitable diluent provides the necessary viscosity and rheological properties for application and doctoring, and on drying off excess water forms a matrix binding the particulate permanent constituent together, to form a flexible, solid green tape. Drying at 25-2000C may be accomplished using batch or belt ovens in air or an inert atmosphere. The green tape at this stage is able to receive a screen printed layer of a conductor pattern.
The green tape is also sufficiently surface active to enable lamination of successive layers of dielectric, which may be accomplished using a uniaxial press, the procedure being carried out at room temperature. On firing, the inorganic binder constituent and various dielectric components form a robust and dense structure.
Firing of green tapes or of multilayer dielectrics containing an inorganic binder may be accomplished using conventional firing profiles, generally bell-shaped, with a peak temperature between 6000C and 1100cm depending on the sintering characteristics of the permanent phases.
In accordance with the invention, the co-firing of multi-layer laminated green tape in air or neutral atmospheres may be accomplished using inorganic binders without the problems of burnout attendant on the use of organic binders.
The following Examples illustrate the invention.
Percentages are by weight.
Example 1 A dielectric slurry was made using an aqueous solution of aluminium acid phosphate having a molar ratio P205:Al203 of 2:1. A quantity of this solution mixed 25 23 with silica powder was used to formulate a slurry suitable for casting green tape by a conventional doctor blading process. The slurry consisted of 22% silica, 39% hydrated aluminium acid phosphate and 39% water. A removable backing strip of acetate sheet was used to support the cast slurry. The cast tape was dried in air at 700C and the acetate sheet removed. It was then fired in a belt furnace with a conventional bell-shaped profile of 90 minutes with 10 minutes at peak of 900 cm. The resultant fired structure was dense and robust.
Example 2 A dielectric slurry was made using an aqueous solution of aluminium acid phosphate having a molar ratio P205:Al203 of 2:1. A quantity of this solution mixed with powdered alumina borosilicate glass was used to formulate a slurry suitable for casting green tape by a conventional doctor blading process. The slurry consisted of 40% glass, 39% hydrated acid phosphate and 21% water. A removable blacking strip of acetate sheet was used to support the cast slurry. The cast tape was dried in air at 700C and the acetate sheet removed. It was then fired in a belt furnace with a conventional bell-shaped profile of 90 minutes with 10 minutes at peak of 9000C. The resultant fired structure was dense and robust.

Claims (9)

1. A layer of substantially uniform thickness, of a composition which comprises a dielectric material and an inorganic binder.
2. A layer according to claim 1, in which the inorganic binder is selected from phosphates, silicates, borates, polyphosphates, polysilicates and polyborates.
3. A layer according to claim 1, in which the inorganic binder is a polyacid of a transition metal.
4. A layer according to claim 1, in which the inorganic binder is selected from potassium polyphosphate and aluminium acid phosphate.
5. A layer according to any preceding claim, in which the dielectric material is selected from alumina, lead borosilicate glass and alumina borosilicate glass.
6. A layer according to any preceding claim, which is 250 to 1000 ssm thick.
7. A layer according to claim 1, substantially as herein described.
8. A process for producing a layer according to any preceding claim, which comprises applying the composition in admixture with a diluent on to an inert substrate, levelling the composition to the substantially uniform thickness, drying the composition, and (if desired) removing the layer of the dried composition from the inert substrate.
9. A multi-layer dielectric which comprises, in alternation, (a) layers according to any of claims 1 to 7 or of layers produced by a process according to claim 8, and (b) conductor material.
GB8721189A 1987-09-09 1987-09-09 Green tape Pending GB2209521A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8721189A GB2209521A (en) 1987-09-09 1987-09-09 Green tape

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8721189A GB2209521A (en) 1987-09-09 1987-09-09 Green tape

Publications (2)

Publication Number Publication Date
GB8721189D0 GB8721189D0 (en) 1987-10-14
GB2209521A true GB2209521A (en) 1989-05-17

Family

ID=10623505

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8721189A Pending GB2209521A (en) 1987-09-09 1987-09-09 Green tape

Country Status (1)

Country Link
GB (1) GB2209521A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992000929A2 (en) * 1990-07-11 1992-01-23 E.I. Du Pont De Nemours And Company Boron aluminum phosphates and boron aluminum phosphosilicates for electronic packaging
EP0535338A1 (en) * 1991-09-30 1993-04-07 Gisulfo Baccini A method to process green-tape type circuits, and device that employs the method
US6749769B2 (en) 2001-03-09 2004-06-15 E. I. Du Pont De Nemours And Company Crystalline compositions of doped aluminum phosphate

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1150465A (en) * 1966-05-13 1969-04-30 Ibm Improvements in and relating to Ceramic Compositions
GB1218008A (en) * 1968-05-31 1971-01-06 Du Pont Dielectric compositions
US3609483A (en) * 1969-07-01 1971-09-28 American Lava Corp Thick film titanate capacitor composition
GB1408256A (en) * 1974-02-08 1975-10-01 Du Pont Dielectric compositions and glass frits for use as components thereof
US4071881A (en) * 1976-03-30 1978-01-31 E. I. Du Pont De Nemours And Company Dielectric compositions of magnesium titanate and devices thereof
GB1513237A (en) * 1975-07-24 1978-06-07 Kkf Corp Coating compositions processes for depositing the same and articles resulting therefrom
GB1548117A (en) * 1976-12-27 1979-07-04 Philips Nv Dielectric compositions

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1150465A (en) * 1966-05-13 1969-04-30 Ibm Improvements in and relating to Ceramic Compositions
GB1218008A (en) * 1968-05-31 1971-01-06 Du Pont Dielectric compositions
US3609483A (en) * 1969-07-01 1971-09-28 American Lava Corp Thick film titanate capacitor composition
GB1408256A (en) * 1974-02-08 1975-10-01 Du Pont Dielectric compositions and glass frits for use as components thereof
GB1513237A (en) * 1975-07-24 1978-06-07 Kkf Corp Coating compositions processes for depositing the same and articles resulting therefrom
US4071881A (en) * 1976-03-30 1978-01-31 E. I. Du Pont De Nemours And Company Dielectric compositions of magnesium titanate and devices thereof
GB1548117A (en) * 1976-12-27 1979-07-04 Philips Nv Dielectric compositions

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992000929A2 (en) * 1990-07-11 1992-01-23 E.I. Du Pont De Nemours And Company Boron aluminum phosphates and boron aluminum phosphosilicates for electronic packaging
WO1992000929A3 (en) * 1990-07-11 1992-08-06 Du Pont Boron aluminum phosphates and boron aluminum phosphosilicates for electronic packaging
EP0535338A1 (en) * 1991-09-30 1993-04-07 Gisulfo Baccini A method to process green-tape type circuits, and device that employs the method
US5314711A (en) * 1991-09-30 1994-05-24 Gisulfo Baccini Method and apparatus for printing green-tape foil circuits
US6749769B2 (en) 2001-03-09 2004-06-15 E. I. Du Pont De Nemours And Company Crystalline compositions of doped aluminum phosphate

Also Published As

Publication number Publication date
GB8721189D0 (en) 1987-10-14

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