GB2098807A - Method of making circuit elements in a film - Google Patents

Method of making circuit elements in a film Download PDF

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Publication number
GB2098807A
GB2098807A GB8115049A GB8115049A GB2098807A GB 2098807 A GB2098807 A GB 2098807A GB 8115049 A GB8115049 A GB 8115049A GB 8115049 A GB8115049 A GB 8115049A GB 2098807 A GB2098807 A GB 2098807A
Authority
GB
United Kingdom
Prior art keywords
substrate
coating
circuit element
parts
circuit assembly
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.)
Granted
Application number
GB8115049A
Other versions
GB2098807B (en
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.)
Ferranti International PLC
Original Assignee
Ferranti PLC
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 Ferranti PLC filed Critical Ferranti PLC
Priority to GB8115049A priority Critical patent/GB2098807B/en
Publication of GB2098807A publication Critical patent/GB2098807A/en
Application granted granted Critical
Publication of GB2098807B publication Critical patent/GB2098807B/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/06—Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base
    • 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
    • H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
    • 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
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/105—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern by conversion of non-conductive material on or in the support into conductive material, e.g. by using an energy beam
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/05—Patterning and lithography; Masks; Details of resist
    • H05K2203/0502—Patterning and lithography
    • H05K2203/0514—Photodevelopable thick film, e.g. conductive or insulating paste
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/10—Using electric, magnetic and electromagnetic fields; Using laser light
    • H05K2203/107—Using laser light
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/12—Using specific substances
    • H05K2203/121—Metallo-organic compounds

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing Of Printed Wiring (AREA)
  • Manufacturing Of Printed Circuit Boards (AREA)

Abstract

A circuit element, such as a conductive track or a resistor, upon selected portions of a substrate 10 of an electrical circuit assembly, is provided by selectively heating parts of a coating 12 of a composition, the heating causing the circuit element, thereby formed from the coating, also to adhere to the substrate; the composition including a glass frit; or the circuit element being formed by dissociation of a suitable compound of the composition. The heating is caused by selectively irradiating the appropriate coating parts with electromagnetic radiation 14, by causing relative movement between the radiation source and the substrate, the arrangement being such that the radiation is incident instantaneously only upon a portion of the substrate, the incident radiation possibly comprising a laser beam. Subsequently, the non-irradiated coating parts selectively are removed. <IMAGE>

Description

SPECIFICATION Electrical circuit assemblies THIS INVENTION relates to electrical circuit assemblies, and in particular to the manufacture of constituent circuit elements of such assemblies, each such circuit element being provided on selected portions of a substrate by, initially coating more than the selected portions of the substrate with a composition, and heating the composition upon the selected substrate portions, by the heating step the required circuit element being formed from the composition, and adheres to the selected substrate portions.
Usually the composition includes a glass frit. However whether the composition includes a glass frit, or not, the composition is required to be such that the heating step causes the circuit element to adhere to the substrate, a suitable substrate being provided for this purpose.
Such a circuit element may comprise, for example, a conductive track, or a resistor.
It is an object of the present invention to provide a novel and advantageous method of so forming a circuit element as referred to above.
According to the present invention a method of manufacturing an electrical circuit assembly at least includes forming a constituent circuit element of the circuit assembly upon selected portions of a suitable substrate, by providing a coating of a composition, from which coating the required circuit element is formed, adhering to the substrate, by a heating step as referred to above, the coating is provided initially upon more than the selected substrate portions, and the method includes irradiating selectively with electromagnetic radiation the parts of the coating upon the selected substrate portions, by causing the appropriate relative movement between a radiation source and the substrate, the arrangement being such that the radiation from the source is incident instantaneously only upon a portion of the substrate, thereby selectively heating these coating parts, as referred to above, and then selectively removing the irradiated coating parts, whereby the required circuit element is provided, adhering to the selected substrate portions.
It is essential that the incident electromagnetic radiation is such that it is absorbed by the composition, and it is essential that the intensity of the incident radiation observed by the coating is sufficient to cause the temperature of the selected parts of the coating to rise sufficiently for the required circuit element to be formed, adhering to the selected substrate portions. The coated substrate may be maintained at an elevated temperature, but below the required temperature for the formation of the circuit element, before the selected parts of the coating are irradiated, the incident radiation causing the approporiate coating parts selectively to be heated as referred to above.
The incident electromagnetic radiation may comprise a laser beam.
Any such method is advantageous in that it obviates having to deposit the composition selectively only upon appropriate portions of the substrate, to provide a coating of the required shape in plan of the desired circuit element. Hence, there is obviated having to perform a complex, selective screen printing, or photolithographic etching, process step.
The appropriate relative movement between the radiation source and the substrate can be caused in any convenient way. Thus, there is obviated the need to provide a mask to define the shape in plan of the desired circuit element, requiring the radiation incident upon the substrate to be transmitted by the mask.
The use of a mask is disadvantageous because it absorbs some of the radiant energy, from an extensive source, and incident upon it, reducing the temperature which can be obtained for the irradiated coating parts on the selected substrate portions. Further, the use of a mask causes the resolution by which the desired circuit element is defined to be less than that obtainable by producing the desired circuit element by causing the appropriate relative movement between the radiation source and the substrate, in accordance with the present invention.
Conveniently, the composition includes a glass frit.
If the composition does not include a glass frit, it may at least include a compound which dissociates by being irradiated, causing the required circuit element to be deposited upon, and to adhere to, the substrate.
According to another aspect the present invention comprises an electrical circuit assembly having a constituent circuit element formed in any one of the ways referred to above.
The present invention will now be described by way of example with reference to the accompanying drawing, comprising a crosssection of part of one embodiment of an electrical circuit assembly in accordance with the present invention.
The illustrated part of an electrical circuit assembly comprises an electrically insulating substrate 10, having at least one planar surface 11, 5 centimetres square. The whole of the surface 11 is provided with a coating 12 of a composition comprising:~ gold glass frit an organic binder The coating is provided in any convenient way, for example, by screen printing.
The coating has a thickness in the range 20 to 25 micrometres.
A laser beam, indicated generally at 14, having a wavelength of 1.06 micrometres, and having a diameter of 25 micrometres, is caused to irradiate selectively parts of the coating 12 required to form a desired circuit element, the circuit element comprising a conductive track of the circuit assembly. This irradiation causes, in relation to the selected coating parts 12', the oxidation of the organic binder, and the fusion of the glass frit, and the gold, to the substrate.
Subsequently, the parts of coating remaining non-irradiated selectively, are removed, leaving the required conductive track 12' on the substrate. The non-irradiated coating parts can be removed in any convenient way, for example, by immersion in butyl carbitol, terpineol, etc., and ultrasonically agitating the liquid.
The selected parts 12' of the coating are heated, or fired, by causing movement of the incident laser beam over the selected coating parts, in any convenient manner, for example, the laser beam source being displaced in response to a known form of electrical programming means. The relative movement may be in the form of a raster scan pattern, the intensity of the radiation emitted by the laser beam source being modulated in the required manner for the formation of the circuit element; or can be along the required path for the formation of the circuit element.
It is essential that the laser beam is absorbed by the composition, and it is essential that the intensity of the incident radiation absorbed by the coating is sufficient to cause the temperature of the selected parts of the coating to rise above the melting point of the glass frit of the composition.
Before the selected parts of the coating are irradiated, the coated substrate may be maintained at an elevated temperature, below the required temperature for the formation of the circuit element, but possibly sufficient to cause the oxidation of the organic binder.
Then the incident radiation causes the appropriate coating parts selectively to be fused.
The composition may not include a glass frit if the circuit element is formed, and adheres satisfactorily to the substrate after the appropriate coating parts are heated. Thus, the coating may comprise a metal compound, which dissociates, depositing the metal, when heated, by irradiation, at a temperature greater than 400 . The metal selectively deposited in this manner adheres well to the substrate, and forms a circuit element comprising a conductive track. The non-irradiated resinate compound portions selectively may be removed by immersion in a suitable organic solvent, and ultrasonically agitating the liquid. The coating is provided by screen printing; and the coating has a thickness in the range 20 to 25 micrometres. The incident laser beam has a wavelength of 1.06 micrometres.
A suitable form of substrate is required to be provided in any method in accordance with the present invention, and may be of glass, or a glazed ceramic, or an as-fired ceramic, or sapphire, or silicon.
Other forms of circuit element, than conductive tracks, for example, resistors, may be formed in this way, parts of coatings of appropriate, different compositions being heated selectively, by being irradiated selectively.
The radiation may not comprise a laser.
The electromagnetic radiation incident upon the composition may be in any part of the spectrum.
The arrangement may be such that movement of the source of the radiation is controlled in any convenient way, so that the appropriate coating parts selectively are irradiated.
Alternatively, the arrangement may be such that the coated substrate is moved in the required manner relative to a stationary, or independently displaceable, source of the incident radiation.
If a fine track of deposited material is required for the circuit element, and there is the possibility of a discontinuous track being formed by a method in accordance with the present invention, after the selective removal of the non-irradiated parts of the coating, the electrical circuit assembly may be heated in a furnace to ensure that any such discontinuity of the required circuit element does not occur.

Claims (12)

1. A method of manufacturing an electrical circuit assembly at least including forming a constituent circuit element of the circuit assembly upon selected portions of a suitable substrate, by providing a coating of a composition, from which coating the required circuit element is formed, adhering to the substrate, by a heating step, the coating being provided initially upon more than the selected substrate portions, and the method including irradiating selectively with electromagnetic radiation the parts of the coating upon the selected substrate portions, by causing the appropriate relative movement between a radiation source and the substrate, the arrangement being such that the radiation from the source is incident instantaneously only upon a portion of the substrate, thereby selectively heating these coating parts, and then selectively removing the non-irradiated coating parts.
2. A method as claimed in claim 1 in which the coated substrate is maintained at an elevated temperature, below the required temperature for the formation of the circuit element, before the selected parts of the coating are irradiated.
3. A method as claimed in claim 1 or claim 2 in which the incident electromagnetic radiation comprises a laser beam.
4. A method as claimed in claim 3 in which the relative movement between the source of the incident electromagnetic radiation and the substrate is controlled by electrical programming means.
5. A method as claimed in any one of the preceding claims in which the composition includes a glass frit.
6. A method as claimed in any one of claims 1 to 4 having the composition at least including a compound which dissociates by being heated, causing the required circuit element to be deposited upon, and to adhere to, the substrate.
7. A method as claimed in claim 6 in which the compound is a metal resinate compound.
8. A method as claimed in any one of the preceding claims in which the electrical circuit assembly is heated in a furnace after the selective removal of the non-irradiated coating parts.
9. An electrical circuit assembly manufactured by a method as claimed in any one of the preceding claims.
10. A circuit assembly as claimed in claim 9 in which the constituent circuit element is a resistor or a conductive track.
11. A method of manufacturing an electrical circuit assembly substantially as described herein with reference to the accompanying drawing.
12. An electrical circuit assembly substantially as described herein with reference to the accompanying drawing.
GB8115049A 1981-05-16 1981-05-16 Method of making circuit elements in a film Expired GB2098807B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8115049A GB2098807B (en) 1981-05-16 1981-05-16 Method of making circuit elements in a film

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8115049A GB2098807B (en) 1981-05-16 1981-05-16 Method of making circuit elements in a film

Publications (2)

Publication Number Publication Date
GB2098807A true GB2098807A (en) 1982-11-24
GB2098807B GB2098807B (en) 1985-07-24

Family

ID=10521855

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8115049A Expired GB2098807B (en) 1981-05-16 1981-05-16 Method of making circuit elements in a film

Country Status (1)

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GB (1) GB2098807B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2160712A (en) * 1984-06-21 1985-12-24 Stc Plc Forming conductive tracks on circuit boards
EP0252451A2 (en) * 1986-07-05 1988-01-13 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho Substrate of hybrid ic, method of forming a circuit pattern and apparatus of forming the same
GB2213325A (en) * 1987-12-04 1989-08-09 Marconi Electronic Devices A method of forming electrical conductors on an insulating substrate
GB2246476A (en) * 1990-04-17 1992-01-29 Nippon Cmk Kk Forming carbon resistance on P.C.B.
EP0476320A1 (en) * 1990-09-18 1992-03-25 Robert Bosch Gmbh Process for manufacturing conductive structures in thick film technique

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2160712A (en) * 1984-06-21 1985-12-24 Stc Plc Forming conductive tracks on circuit boards
EP0252451A2 (en) * 1986-07-05 1988-01-13 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho Substrate of hybrid ic, method of forming a circuit pattern and apparatus of forming the same
EP0252451A3 (en) * 1986-07-05 1988-12-14 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho Substrate of hybrid ic, method of forming a circuit pattern and apparatus of forming the same
GB2213325A (en) * 1987-12-04 1989-08-09 Marconi Electronic Devices A method of forming electrical conductors on an insulating substrate
GB2213325B (en) * 1987-12-04 1992-01-02 Marconi Electronic Devices A method of forming electrical conductors
GB2246476A (en) * 1990-04-17 1992-01-29 Nippon Cmk Kk Forming carbon resistance on P.C.B.
GB2246476B (en) * 1990-04-17 1993-11-17 Nippon Cmk Kk A method of forming a carbon resistance on a printed wiring board
EP0476320A1 (en) * 1990-09-18 1992-03-25 Robert Bosch Gmbh Process for manufacturing conductive structures in thick film technique

Also Published As

Publication number Publication date
GB2098807B (en) 1985-07-24

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee