GB2054958A - Substrate for a microwave integrated circuit - Google Patents

Substrate for a microwave integrated circuit Download PDF

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Publication number
GB2054958A
GB2054958A GB8022414A GB8022414A GB2054958A GB 2054958 A GB2054958 A GB 2054958A GB 8022414 A GB8022414 A GB 8022414A GB 8022414 A GB8022414 A GB 8022414A GB 2054958 A GB2054958 A GB 2054958A
Authority
GB
United Kingdom
Prior art keywords
substrate
plate
integrated circuit
microwave integrated
dielectric material
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.)
Withdrawn
Application number
GB8022414A
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.)
GEC GB
General Electric Co Ltd
Original Assignee
GEC GB
General Electric Co 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
Priority to GB7925595 priority Critical
Application filed by GEC GB, General Electric Co Ltd filed Critical GEC GB
Priority to GB8022414A priority patent/GB2054958A/en
Publication of GB2054958A publication Critical patent/GB2054958A/en
Application status is Withdrawn legal-status Critical

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • 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
    • H01L23/142Metallic substrates having insulating layers
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • 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

Abstract

A substrate for a microwave integrated circuit comprising a self- supporting electrically conductive plate with a relatively thin layer of dielectric material adhering to a main face thereof. Typically the plate consists of molybdenum and the dielectric material is borosilicate glass. In use, the plate serves as circuit earth plane conductor.

Description

SPECIFICATION Microwave integrated circuits This invention relates to microwave integrated circuits.

The invention relates particularly to substrates for use in such circuits.

For circuits operating at lower frequencies, e.g.

below 20 GHz, such substrates conventionally comprise a wafer of dielectric material, such as alumina ceramic, having an earth plane conductor deposited on one main face, the microwave circuit component and interconnections being carried on the other main face. For higher frequencies, e.g. in the range 20 GHz to 100 GHz, such a substrate is still satisfactory although dielectric materials of low permittivity must be used for the wafer in order that the wafer may be sufficiently thick and therefore strong to be handled without breakage and support the earth plane conductor, components and interconnections. However, at a frequency of 100 GHz, even when using a dielectric material of low permittivity the required wafer thickness is typically only 0.1 millimetre, and at higher frequencies progressively thinner wafers must be used which are very difficult to handle without breakage.

It is an object of the present invention to provide a substrate for a microwave integrated circuit whereby this difficulty is overcome.

According to the present invention a substrate for a microwave integrated circuit comprises a self-supporting electrically conductive plate with a relatively thin layer of dielectric material adhering to a main face thereof.

It will be appreciated that in use the plate serves as the circuit earth plane conductor.

In a preferred arrangement in accordance with the invention said dielectric layer comprises a fused glass layer.

The dielectric layer is suitably formed by covering said face of the plate with a layer of the dielectric material in particulate form and heating.

The plate and layer preferably consist of materials having closely matched thermal expansion characteristics, One substrate in accordance with the invention and its manufacture will now be described by way of example.

The substrate comprises a molybdenum plate on one main face of which there is an adherent relatively thin borosilicate glass layer.

The substrate is formed by covering the relevant face of the plate with a borosilicate glass frit and heating. The fused glass layer so formed is then ground and polished to the required thickness.

The required microwave circuit can be fabricated on the substrate in conventional manner.

In one particular substrate for use in fabricating an integrated circuit for operation at 100 GHz the plate has a thickness of 1 millimetre and the glass layer a thickness of 0.1 millimetre.

It might be thought that since the dielectric loss of suitable glasses such as borosilicate glass is higher than that of alumina the dielectric loss in the substrate might be excessive. However, as operating frequency is increased, other factors being constant, the fraction of the total loss attributable to dielectric loss falls. Thus, for a circuit element which is scaled according to the operating wavelength, and assuming constant effective conductivity, permittivity and loss tangent, the conductor loss increases as the square root of frequency, whereas the dielectric loss contribution is constant. Thus the dielectric loss obtained with glass at high frequencies e.g.

above 100 GHz is in fact quite tolerable.

Claims (9)

1. A substrate for a microwave integrated circuit comprising a self-supporting electrically conductive plate with a relatively thin layer of dielectric material adhering to a main face thereof.
2. A substrate according to Claim 1 wherein said dielectric layer comprises a fused glass layer.
3. A substrate according to Claim 2 wherein said plate consists of molybdenum and said dielectric material is borosilicate glass.
4. A substrate according to Claim 2 or Claim 3 wherein said plate has a thickness of 1 millimetre and said glass layer has a thickness of 0.1 millimetre.
5. A substrate for a microwave integrated circuit substantially as hereinbefore described by way of example.
6. A microwave integrated circuit incorporating a substrate according to any one of the preceding claims, the plate serving as the circuit earth plane conductor and the microwave circuit components and interconnections being carried on the face of said thin layer remote from the plate.
7. A method of making a substrate according to any one of Claims 1 to 5 comprising covering a main face of a plate of electrically conductive material with a layer of dielectric material in particulate form and heating so as to cause the particles of dielectric material to fuse.
8. A method according to Claim 7 wherein the fused layer is ground and polished to the required thickness.
9. A method of making a substrate for a microwave integrated circuit substantially as hereinbefore described by way of example.
GB8022414A 1979-07-23 1980-07-09 Substrate for a microwave integrated circuit Withdrawn GB2054958A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB7925595 1979-07-23
GB8022414A GB2054958A (en) 1979-07-23 1980-07-09 Substrate for a microwave integrated circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8022414A GB2054958A (en) 1979-07-23 1980-07-09 Substrate for a microwave integrated circuit

Publications (1)

Publication Number Publication Date
GB2054958A true GB2054958A (en) 1981-02-18

Family

ID=26272288

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8022414A Withdrawn GB2054958A (en) 1979-07-23 1980-07-09 Substrate for a microwave integrated circuit

Country Status (1)

Country Link
GB (1) GB2054958A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0099258A2 (en) * 1982-07-14 1984-01-25 United Kingdom Atomic Energy Authority Substrates for electronic devices
FR2560818A1 (en) * 1984-03-07 1985-09-13 Taiyo Yuden Kk flexible insulating substrates comprising two layers of glass on at least one side thereof, and method of manufacturing such substrates

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0099258A2 (en) * 1982-07-14 1984-01-25 United Kingdom Atomic Energy Authority Substrates for electronic devices
EP0099258A3 (en) * 1982-07-14 1985-11-06 United Kingdom Atomic Energy Authority Substrates for electronic devices
FR2560818A1 (en) * 1984-03-07 1985-09-13 Taiyo Yuden Kk flexible insulating substrates comprising two layers of glass on at least one side thereof, and method of manufacturing such substrates

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Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)